LA COLLA PAOLO (IT)
STORER RICHARD (GB)
GOSSELIN GILLES (FR)
CENTRE NAT RECH SCIENT (FR)
UNIV CAGLIARI (IT)
SOMMADOSSI JEAN-PIERRE (US)
LA COLLA PAOLO (IT)
STORER RICHARD (GB)
GOSSELIN GILLES (FR)
| WO2000009531A2 | 2000-02-24 | |||
| WO2001096353A2 | 2001-12-20 | |||
| WO2001090121A2 | 2001-11-29 | |||
| WO2001092282A2 | 2001-12-06 | |||
| WO1991019721A1 | 1991-12-26 |
| US4957924A | 1990-09-18 | |||
| US5157027A | 1992-10-20 |
FIELDS, B. N., KNIPE, D. M., AND HOWLEY, P. M.,: "Fields Virology", 1996, LIPPINCOTT-RAVEN PUBLISHERS, article "Chapter 31", pages: 931 - 959
HALSTEAD, S. B., REV. INFECT.
FRANCHETTI P. ET AL.: "synthesis and binding studies of 2'-C-Methyl analogues of selective adenosine receptor agonists", JOURNAL OF MEDICINAL CHEMISTRY, vol. 41, 1998, pages 1708 - 1715, XP002189348, DOI: doi:10.1021/jm9707737
WOLF J. ET AL.: "Synthesis", 1992, GEORG THIEME VERLAG, article "2'-C-branched-chain sugar nucleoside analogs with potential antiviral or antitumor activity"
MATSUDA A. ET AL.: "Chemical and Pharmaceutical Bulletin", vol. 35, 1987, article "synthesis and antileukimic activity of deoxy-2'(S)-methylcytidine", pages: 3967 - 3970
JOURNAL OF MEDICINAL CHEMISTRY, vol. 34, 1991, pages 234 - 239
AWANO ET AL.: "synthesis and antiviral activity of 5-substituted (2'S)-2'-deoxy-2'-C-methylcytidines and -uridines", ARCHIV DER PHARMAZIE, vol. 329, 1996, pages 66 - 72, XP000611444, DOI: doi:10.1002/ardp.19963290203
LI N.-S. ET AL.: "synthesis of 2'-C-beta-trifluoromethyl pyrimidine ribonucleosides", ORG. LETT., vol. 3, 2001, pages 1025 - 1028, XP002287440, DOI: doi:10.1021/ol0155687
SCHMIT ET AL.: "synthesis of 2'-deoxy-2'-alpha-monofluoromethyl and trifluoromethylnucleosides", SYNLETT, vol. 4, 1994, pages 241 - 242, XP002056163, DOI: doi:10.1055/s-1994-22810
DELAMBERT ET AL., J. MED CHEM., vol. 37, 1994, pages 498
KHAMNEI; TORRENCE, J. MED CHEM., vol. 39, 1996, pages 4109 - 4115
MITCHELL ET AL., J. CHEM. SOC. PERKIN TRANS. I, 1992, pages 2345
HUNSTON ET AL., J. MED CHEM., vol. 27, 1984, pages 440 - 444
STARRETT ET AL., J. MED. CHEM., vol. 37, 1994, pages 1857 - 1864
MEIER ET AL., J. MED CHEM., vol. 22, 1979, pages 811 - 815
MEIER ET AL., BIOORG. MED CHEM. LETT., vol. 7, 1997, pages 99 - 104
FARQUHAR ET AL., J. MED CHEM., vol. 26, 1983, pages 1153
FARQUHAR ET AL., J. MED. CHEM., vol. 28, 1985, pages 1358
FREED ET AL., BIOCHEM. PHARMAC., vol. 38, 1989, pages 3193
ZON, PROGRESS IN MED. CHEM., vol. 19, 1982, pages 1205
"Townsend Chemistry of Nucleosides and Nucleotides", 1994, PLENUM PRESS
GREENE ET AL.: "Protective Groups in Organic Synthesis, Second Edition,", 1991, JOHN WILEY AND SONS
| 1. | A compound of Formula (I), or a pharmaceutically acceptable salt thereof, of the formula: wherein: Rl, R and R3 are independently H, phosphate or a stabilized phosphate; straight chained, branched or cyclic alkyl ; acyl ; COalkyl ; COaryl ; COalkoxyalkyl ; COaryloxyalkyl ; CO substituted aryl; sulfonate ester; benzyl, wherein the phenyl group is optionally substituted with one or more substituents; alkylsulfonyl ; arylsulfonyl ; aralkylsulfonyl ; a lipid ; an amino acid; an amino acid residue; a carbohydrate; a peptide; cholesterol ;. or a pharmaceutically acceptable leaving group which when administered in vivo is capable of providing a compound wherein R', W and/or R3 is independently H or phosphate; wherein at least one of R2 and R3 is not hydrogen; Y is hydrogen, bromo, chloro, fluoro, iodo, OH, OR4, NH, NHR5, NR4R5, SH and SR4 ; X1 and X2 are independently selected from the group consisting of H, straight chained, branched or cyclic alkyl, COalkyl, COaryl, COalkoxyalkyl, chloro, bromo, fluoro, iodo, OH, OR4, NH, NHR5, NR4R5, SH and SR4 ; and R4 and R5 are independently hydrogen, acyl, or alkyl. |
| 2. | A compound of Formula II, or a pharmaceutically acceptable salt of the formula: wherein: R', R2 and R3 are independently H, phosphate or a stabilized phosphate; straight chained, branched or cyclic alkyl ; acyl ; COalkyl ; COaryl ; COalkoxyalkyl ; COaryloxyalkyl ; CO substituted aryl ; sulfonate ester; benzyl, wherein the phenyl group is optionally substituted with one or more substituents; alkylsulfonyl ; arylsulfonyl ; aralkylsulfonyl ; a lipid; an amino acid; an amino acid residue; a carbohydrate; a peptide; cholesterol; or a pharmaceutically acceptable leaving group which when administered in vivo is capable of providing a compound wherein Rl, W and/or R3 is independently H or phosphate; wherein at least one of R2 and R3 is not hydrogen; Y is hydrogen, bromo, chloro, fluoro, iodo, OR4, NR4R5 or SR4 ; Xl and X2 are independently selected from the group consisting of H, straight chained, branched or cyclic alkyl, COalkyl, COaryl, COalkoxyalkyl, chloro, bromo, fluoro, iodo, OR4, NR4NR5 or SR5 ; and R4 and R5 are independently hydrogen, acyl, or alkyl. |
| 3. | A compound of Formula III, or a pharmaceutically acceptable salt thereof wherein: Rl, R2 and R3 are independently H, phosphate or a stabilized phosphate; straight chained, branched or cyclic alkyl ; acyl ; COalkyl ; COaryl ; COalkoxyalkyl ; COaryloxyalkyl ; CO substituted aryl; sulfonate ester; benzyl, wherein the phenyl group is optionally substituted with one or more substituents; alkylsulfonyl ; arylsulfonyl ; aralkylsulfonyl ; a lipid; an amino acid; an amino acid residue; a carbohydrate; a peptide; cholesterol ; or a pharmaceutically acceptable leaving group which when administered in vivo is capable of providing a compound wherein Rl, R2 and/or R3 is independently H or phosphate; wherein at least one of R2 and R3 is not hydrogen; Y is hydrogen, bromo, chloro, fluoro, iodo, OR4, NR4R5 or SR4 ; Xl and x2 are independently selected from the group consisting of H, straight chained, branched or cyclic alkyl, COalkyl, COaryl, COalkoxyalkyl, chloro, bromo, fluoro, iodo, oR4 NR4NR5 or SR5 ; and R4 and R5 are independently hydrogen, acyl, or alkyl. |
| 4. | A compound of Formula IV, or a pharmaceutically acceptable salt or prodrug thereof : wherein: R', R2 and R3 are independently H, phosphate or a stabilized phosphate; straight chained, branched or cyclic alkyl ; acyl ; COalkyl ; COaryl ; COalkoxyalkyl ; COaryloxyalkyl ; CO substituted aryl ; sulfonate ester; benzyl, wherein the phenyl group is optionally substituted with one or more substituents; alkylsulfonyl ; arylsulfonyl ; aralkylsulfonyl ; a lipid ; an amino acid; an amino acid residue; a carbohydrate; a peptide; cholesterol ; or a pharmaceutically acceptable leaving group which when administered in vivo is capable of providing a compound wherein Rl, R2 and/or R3 is independently H or phosphate; wherein at least one of R2 and R3 is not hydrogen; Y is hydrogen, bromo, chloro, fluoro, iodo, OR4, NR4R5 or SR4 ; Xi vis selected from the group consisting of H, straight chained, branched or cyclic alkyl, CO alkyl, COaryl, COalkoxyalkyl, chloro, bromo, fluoro, iodo, OR4, NR4NR5 or SR5 ; and R4 and R5 are independently hydrogen, acyl, or alkyl. |
| 5. | A compound of Formula V, or a pharmaceutically acceptable salt or prodrug thereof : wherein: Rl, R2 and R3 are independently H, phosphate or a stabilized phosphate; straight chained, branched or cyclic alkyl ; acyl ; COalkyl ; COaryl ; COalkoxyalkyl ; COaryloxyalkyl ; CO substituted aryl ; sulfonate ester; benzyl, wherein the phenyl group is optionally substituted with one or more substituents; alkylsulfonyl ; arylsulfonyl ; aralkylsulfonyl ; a lipid ; an amino acid; an amino acid residue; a carbohydrate; a peptide; cholesterol ; or a pharmaceutically acceptable leaving group which when administered in vivo is capable of providing a compound wherein Rl, W and/or R3 is independently H or phosphate; wherein at least one of R2 and R3 is not hydrogen; Y is hydrogen, bromo, chloro, fluoro, iodo, OR4, NR4R5 or SR4 ; Xi vis selected from the group consisting of H, straight chained, branched or cyclic alkyl, CO alkyl, COaryl, COalkoxyalkyl, chloro, bromo, fluoro, iodo, OR4, NR4NR5 or SRs ; and R4 and R5 are independently hydrogen, acyl, or alkyl. |
| 6. | A compound of Formula VI or a pharmaceutically acceptable salt or prodrug thereof : wherein: R', R2 and R3 are independently H, phosphate or a stabilized phosphate; straight chained, branched or cyclic alkyl ; acyl ; COalkyl ; COaryl ; COalkoxyalkyl ; COaryloxyalkyl ; CO substituted aryl ; sulfonate ester; benzyl, wherein the phenyl group is optionally substituted with one or more substituents; alkylsulfonyl ; arylsulfonyl ; aralkylsulfonyl ; a lipid ; an amino acid; an amino acid residue; a carbohydrate; a peptide; cholesterol ; or a pharmaceutically acceptable leaving group which when administered in vivo is capable of providing a compound wherein R', R2 and/or R3 is independently H or phosphate; wherein at least one of R2 and R3 is not hydrogen; Y is hydrogen, bromo, chloro, fluoro, iodo, OR4, NR4R5 or SR4 ; Xl is selected from the group consisting of H, straight chained, branched or cyclic alkyl, CO alkyl, COaryl, COalkoxyalkyl, chloro, bromo, fluoro, iodo, OR4, NR4NR5 or SR5 ; and R4 and R5 are independently hydrogen, acyl (including lower acyl), or alkyl (including but not limited to methyl, ethyl, propyl and cyclopropyl). |
| 7. | A compound selected from Formulas VII and VIII, or a pharmaceutically acceptable salt or prodrug thereof : wherein: Base is a purine or pyrimidine base; R', R2 and R3 are independently H, phosphate or a stabilized phosphate; straight chained, branched or cyclic alkyl ; acyl ; COalkyl ; COaryl ; COalkoxyalkyl ; COaryloxyalkyl ; CO substituted aryl ; sulfonate ester; benzyl, wherein the phenyl group is optionally substituted with one or more substituents; alkylsulfonyl ; arylsulfonyl ; aralkylsulfonyl ; a lipid ; an amino acid; an amino acid residue; a carbohydrate; a peptide; cholesterol; or a pharmaceutically acceptable leaving group which when administered in vivo is capable of providing a compound wherein RI, R2 and/or R3 is independently H or phosphate; wherein R2 is not hydrogen; R6 is alkyl, CH3, CF3, azido, cyano, alkenyl, alkynyl, Brvinyl, 2Brethyl,C (O) O (alkyl), C (O) O (lower alkyl),O (acyl),O (lower acyl),O (alkyl),O (lower alkyl),O (alkenyl), CF3, chloro, bromo, fluoro, iodo, NO2, NH2, NH (lower alkyl),NH (acyl), N (lower alkyl) 2, N (acyl) 2; and X is O, S, SO2 or CH2. |
| 8. | A compound of Formulas IX and X, or a pharmaceutically acceptable salt : wherein: Base is a purine or pyrimidine base; R', R2 and R3 are independently H, phosphate or a stabilized phosphate; straight chained, branched or cyclic alkyl ; acyl ; COalkyl ; COaryl ; COalkoxyalkyl ; COaryloxyalkyl ; CO substituted aryl ; sulfonate ester; benzyl, wherein the phenyl group is optionally substituted with one or more substituents; alkylsulfonyl ; arylsulfonyl ; aralkylsulfonyl ; a lipid ; an amino acid; an amino acid residue; a carbohydrate; a peptide; cholesterol ; or a pharmaceutically acceptable leaving group which when administered in vivo is capable of providing a compound wherein Rl, R2 and/or R3 is independently H or phosphate; wherein R2 is not hydrogen; R6 is alkyl, CH3, CF3, azido, cyano, alkenyl, alkynyl, Brvinyl, 2Brethyl,C (O) O (alkyl), C (O) O (lower alkyl),O (acyl),O (lower acyl),O (alkyl),O (lower alkyl),O (alkenyl), CF3, chloro, bromo, fluoro, iodo, NO2, NH2,NH (lower alkyl),NH (acyl),N (lower alkyl) 2, N (acyl) 2; and R7 is hydrogen, OR3, hydroxy, alkyl, azido, cyano, alkenyl, alkynyl, Brvinyl,C (O) O (alkyl), C(O)O(lower alkyl), O(acyl), O(lower acyl), O(alkyl), O(lower alkyl), O(alkenyl), chlorine, bromine, iodine, NO2, NH2,NH (lower alkyl),NH (acyl),N (lower alkyl) 2, N (acyl) 2; and X is O, S, S02 or CH2. |
| 9. | A compound selected from Formulas XI and XII, or a pharmaceutically acceptable salt thereof : wherein: Base is a purine or pyrimidine base; R', R2 and R3 are independently H, phosphate or a stabilized phosphate; straight chained, branched or cyclic alkyl ; acyl ; COalkyl ; COaryl ; COalkoxyalkyl ; COaryloxyalkyl ; CO substituted aryl ; sulfonate ester; benzyl, wherein the phenyl group is optionally substituted with one or more substituents; alkylsulfonyl ; arylsulfonyl ; aralkylsulfonyl ; a lipid ; an amino acid; an amino acid residue; a carbohydrate; a peptide; cholesterol ; or a pharmaceutically acceptable leaving group which when administered in vivo is capable of providing a compound wherein Rl, R2 and/or R3 is independently H or phosphate; wherein R2 is not hydrogen; R6 is alkyl, CH3, CF3, azido, cyano, alkenyl, alkynyl, Brvinyl, 2Brethyl,C (O) O (alkyl), C (O) O (lower alkyl),O (acyl),O (lower acyl),O (alkyl),O (lower alkyl),O (alkenyl), CF3, chloro, bromo, fluoro, iodo, NO2, NH2, NH (lower alkyl),NH (acyl),N (lower alkyl) 2, N (acyl) 2; and X is O, S, S02 or CH2. |
| 10. | A compound of Formula XIII, or a pharmaceutically acceptable salt thereof : wherein: Base is a purine or pyrimidine base; R', R2 and R3 are independently H, phosphate or a stabilized phosphate; straight chained, branched or cyclic alkyl ; acyl ; COalkyl ; COaryl ; COalkoxyalkyl ; COaryloxyalkyl ; CO substituted aryl ; sulfonate ester; benzyl, wherein the phenyl group is optionally substituted with one or more substituents; alkylsulfonyl ; arylsulfonyl ; aralkylsulfonyl ; a lipid ; an amino acid; an amino acid residue; a carbohydrate; a peptide; cholesterol ; or a pharmaceutically acceptable leaving group which when administered in vivo is capable of providing a compound wherein RI, W and/or R3 is independently H or phosphate; R6 is alkyl, CH3, CF3, azido, cyano, alkenyl, alkynyl, Brvinyl, 2Brethyl,C (O) O (alkyl), C (O) O (lower alkyl),O (acyl),O (lower acyl),O (alkyl),O (lower alkyl),O (alkenyl), CF3, chloro, bromo, fluoro, iodo, NO2, NH2,NH (lower alkyl),NH (acyl),N (lower alkyl) 2, N (acyl) 2; R7 and R9 are independently hydrogen, OR2, hydroxy, alkyl, azido, cyano, alkenyl, alkynyl, <BR> <BR> <BR> <BR> Brvinyl,C (O) O (alkyl),C (O) O (lower alkyl),O (acyl),O (lower acyl),O (alkyl),O (lower alkyl),O (alkenyl), chlorine, bromine, iodine, NO2, NH2, NH (lower alkyl),NH (acyl), N (lower alkyl) 2, N (acyl) 2; wherein at least one of R7 and R9 is OR2, wherein each R2 is independently phosphate or stabilized phosphate; straight chained, branched or cyclic alkyl ; acyl ; COalkyl, COaryl, CO alkoxyalkyl, COaryloxyalkyl, COsubstituted aryl, sulfonate ester, wherein the phenyl group is optionally substituted with one or more substituents; alkylsulfonyl, arylsulfonyl, aralkylsulfonyl, a lipid ; an amino acid; and amino acid residue, a carbohydrate; a peptide; cholesterol; or other pharmaceutically acceptable leaving group which when administered in vivo is capable of providing a compound wherein R2 is H or phosphate; R and Rl° are independently H, alkyl, chlorine, bromine or iodine; alternatively, R7 and Rl°, R8 and R9, or R and Rl° can come together to form a pi bond; and X is O, S, SO2 or CH2. |
| 11. | A method for the treatment of a host infected with a Flaviviridae virus, comprising administering an effective treatment amount of a compound or a pharmaceutically acceptable salt thereof as claimed in any one of claims 110. |
| 12. | The method of claim 11, wherein the virus is hepatitis C. |
| 13. | The method of claim 11, wherein the compound or pharmaceutically acceptable salt thereof, is administered in combination or alternation with a second antiviral agent. |
| 14. | The method of claim 13 wherein the second antiviral agent is selected from the group consisting of an interferon, a ribavirin, an interleukin, a NS3 protease inhibitor, a cysteine protease inhibitor, a phenanthrenequinone, a thiazolidine derivative, a thiazolidine, a benzanilide, a phenanthrenequinone, a helicase inhibitor, a polymerase inhibitor, a nucleotide analogue, a gliotoxin, a cerulenin, an antisense phosphorothioate oligodeoxynucleotide, an inhibitor of IRESdependent translation, and a ribozyme. |
| 15. | The method of claim 14, wherein the second antviral agent is an interferon. |
| 16. | The method of claim 15, wherein the second agent is selected from the group consisting of pegylated interferon alpha 2a, interferon alphacon1, natural interferon, albuferon, interferon betala, omega interferon, interferon alpha, interferon gamma, interferon tau, interferon delta and interferon gammalb. |
| 17. | The method of claim 11, wherein the compound or pharmaceutically acceptable salt thereof, is in the form of a dosage unit. |
| 18. | The method of claim 17, wherein the dosage unit contains 50 to 1000 mg or 0.1 to 50 mg of the compound. |
| 19. | The method of claim 17, wherein the dosage unit is a tablet or capsule. |
| 20. | The method of claim 11, wherein the host is a human. |
| 21. | The method of claim 11, wherein the wherein the compound or pharmaceutically acceptable salt thereof, is in substantially pure form. |
| 22. | The method of claim 11, wherein the compound or stereoisomeric or tautomeric form thereof, or pharmaceutically acceptable salt thereof, is at least 90% by weight of the (3Disomer. |
| 23. | The method of claim 11, wherein the compound or stereoisomeric or tautomeric form thereof, or pharmaceutically acceptable salt thereof, is at least 95% by weight of the (3Disomer. |
| 24. | The method of claim 11, wherein the compound is in the form of a pharmaceutically acceptable salt selected from the group consisting of a tosylate, methanesulfonate, acetate, citrate, malonate, tartarate, succinate, benzoate, ascorate, a ketoglutarate, aglycerophosphate, formate, fumarate, propionate, glycolate, lactate, pyruvate, oxalate, maleate, salicylate, sulfate, nitrate, bicarbonate, carbonate salts, hydrobromate, hydrochloride, dihydrochloride, and phosphoric acid salt. |
| 25. | The method of claim 24, wherein the pharmaceutically acceptable salt is a hydrochloride salt. |
| 26. | A pharmaceutical composition comprising a compound of any of claims I to 10, or a pharmaceutically acceptable salt thereof. |
| 27. | The pharmaceutical composition of claim 26, further comprising a pharmaceutically acceptable carrier, diluent or excipient. |
| 28. | The pharmaceutical composition of claim 26 comprising an effective amount of the compound or a pharmaceutically acceptable salt thereof, for the treatment of a host infected with a Flaviviridae virus. |
| 29. | The composition of claim 28, wherein the Flaviviridae virus is hepatitis C. |
| 30. | The pharmaceutical composition of claim 26, wherein the compound or a pharmaceutically acceptable salt thereof, is in the form of a dosage unit. |
| 31. | The composition of claim 30, wherein the dosage unit contains 50 to 1000 mg or 0.1 to 50 mg of the compound. |
| 32. | The composition of claim 30, wherein said dosage unit is a tablet or capsule. |
| 33. | The pharmaceutical composition of claim 26, further comprising a second antiviral agent. |
| 34. | The pharmaceutical composition of claim 33, wherein the second antiviral agent is selected from the group consisting of an interferon, a ribavirin, an interleukin, a NS3 protease inhibitor, a cysteine protease inhibitor, a phenanthrenequinone, a thiazolidine derivative, a thiazolidine, a benzanilide, a phenanthrenequinone, a helicase inhibitor, a polymerase inhibitor, a nucleotide analogue, a gliotoxin, a cerulenin, an antisense phosphorothioate oligodeoxynucleotide, an inhibitor of IRESdependent translation, and a ribozyme. |
| 35. | The pharmaceutical composition of claim 34, wherein the second antiviral agent is an interferon. |
| 36. | The pharmaceutical composition of claim 35, wherein the second agent is selected from the group consisting of pegylated interferon alpha 2a, interferon alphaconl, natural interferon, albuferon, interferon betala, omega interferon, interferon alpha, interferon gamma, interferon tau, interferon delta and interferon gammalb. |
| 37. | The pharmaceutical composition of claim 26, or pharmaceutically acceptable salt thereof, is in substantially pure form. |
| 38. | The pharmaceutical composition of claim 26, wherein the compound or pharmaceutically acceptable salt thereof; is at least 90% by weight of the (3Disomer. |
| 39. | The pharmaceutical composition of claim 26, wherein the compound or pharmaceutically acceptable salt thereof; is at least 95% by weight of the PDisomer. |
| 40. | The pharmaceutical composition of claim 26, further comprising a pharmaceutically acceptable carrier suitable for oral, parenteral, inhalant or intravenous delivery. |
| 41. | The pharmaceutical composition of claim 26, wherein the compound is in the form of a pharmaceutically acceptable salt selected from the group consisting of a tosylat, methanesulfonate, acetate, citrate, malonate, tartarate, succinate, benzoate, ascorate, a ketoglutarate, aglycerophosphate, formate, fumarate, propionate, glycolate, lactate, pyruvate, oxalate, maleate, salicylate, sulfate, nitrate, bicarbonate, carbonate salts, hydrobromate, a hydrochloride, a dihydrochloride, and phosphoric acid salt. |
| 42. | The pharmaceutical composition of claim 41, wherein the pharmaceutically acceptable salt is a hydrochloride salt. |
| 43. | A compound or a pharmaceutically acceptable salt thereof, of any of claims 1 to 10, for use in the treatment of a host infected with a Flaviviridae virus. |
| 44. | The compound of claim 43, wherein the virus is hepatitis C. |
| 45. | The compound of claim 43, wherein the host is a human. |
| 46. | The use of a compound or a pharmaceutically acceptable salt thereof, of any of claims 1 to 10 in the manufacture of a medicament for the treatment of a host infected with a Flaviviridae virus. |
| 47. | The use of claim 46, wherein the virus is hepatitis C. |
| 48. | The use of claim 46, wherein the host is a human. |
60/392,351, filed June 28,2002 ; U. S. Provisional Application No. 60/466,194, filed April 28, 2003; and U. S. Provisional application 60/470,949, filed May 14,2003, the disclosures of each of which are incorporated herein by reference.
FIELD OF THE INVENTION This invention is in the area of pharmaceutical chemistry, and is in particular, a 2' and/or 3'prodrug of a 1', 2', 3'or 4'-branched nucleosides for the treatment of a Flaviviridae infection, such as a hepatitis C virus infection.
BACKGROUND OF THE INVENTION Flaviviridae Viruses The Flaviviridae family of viruses comprises at least three distinct genera: pestiviruses, which cause disease in cattle and pigs; flaviviruses, which are the primary cause of diseases such as dengue fever and yellow fever; and hepaciviruses, whose sole member is HCV. The flavivirus genus includes more than 68 members separated into groups on the basis of serological relatedness (Calisher et al., J. Gen. Virol, 1993,70, 37-43). Clinical symptoms vary and include fever, encephalitis and hemorrhagic fever (Fields Virology, Editors: Fields, B. N. , Knipe, D. M. , and Howley, P. M., Lippincott-Raven Publishers, Philadelphia, PA, 1996, Chapter 31,931-959). Flaviviruses of global concern that are associated with human disease include the dengue hemorrhagic fever viruses (DHF), yellow fever virus, shock syndrome and Japanese encephalitis virus (Halstead, S. B., Rev. Infect.
Dis., 1984, 6, 251-264; Halstead, S. B., Science, 239: 476-481,1988 ; Monath, T. P., New Eng.
J. Med., 1988, 319, 641-643).
The pestivirus genus includes bovine viral diarrhea virus (BVDV), classical swine fever virus (CSFV, also called hog cholera virus) and border disease virus (BDV) of sheep (Moennig, V. et al. Adv. Vir. Res. 1992, 41, 53-98). Pestivirus infections of domesticated livestock (cattle, pigs and sheep) cause significant economic losses worldwide. BVDV causes mucosal disease in cattle and is of significant economic importance to the livestock industry (Meyers, G. and Thiel, H. -J., Advances in Virus Research, 1996, 47, 53-118; Moennig V. , et al, Adv. Vir. Res. 1992, 41, 53-98). Human pestiviruses have not been as extensively characterized as the animal pestiviruses. However, serological surveys indicate considerable pestivirus exposure in humans.
Pestiviruses and hepaciviruses are closely related virus groups within the Flaviviridae family. Other closely related viruses in this family include the GB virus A, GB virus A-like agents, GB virus-B and GB virus-C (also called hepatitis G virus, HGV). The hepacivirus group (hepatitis C virus; HCV) consists of a number of closely related but genotypically distinguishable viruses that infect humans. There are approximately 6 HCV genotypes and more than 50 subtypes. Due to the similarities between pestiviruses and hepaciviruses, combined with the poor ability of hepaciviruses to grow efficiently in cell culture, bovine viral diarrhea virus (BVDV) is often used as a surrogate to study the HCV virus.
The genetic organization of pestiviruses and hepaciviruses is very similar. These positive stranded RNA viruses possess a single large open reading frame (ORF) encoding all the viral proteins necessary for virus replication. These proteins are expressed as a polyprotein that is co-and post-translationally processed by both cellular and virus-encoded proteinases to yield the mature viral proteins. The viral proteins responsible for the replication of the viral genome RNA are located within approximately the carboxy-terminal.
Two-thirds of the ORF are termed nonstructural (NS) proteins. The genetic organization and polyprotein processing of the nonstructural protein portion of the ORF for pestiviruses and hepaciviruses is very similar. For both the pestiviruses and hepaciviruses, the mature nonstructural (NS) proteins, in sequential order from the amino-terminus of the nonstructural protein coding region to the carboxy-terminus of the ORF, consist of p7, NS2, NS3, NS4A, NS4B, NS5A, and NS5B.
The NS proteins of pestiviruses and hepaciviruses share sequence domains that are characteristic of specific protein functions. For example, the NS3 proteins of viruses in both groups possess amino acid sequence motifs characteristic of serine proteinases and of
helicases (Gorbalenya et al. (1988) Nature 333: 22; Bazan and Fletterick (1989) Virology 171: 637-639; Gorbalenya et al. (1989) Nucleic Acid Res. 17.3889-3897). Similarly, the NS5B proteins of pestiviruses and hepaciviruses have the motifs characteristic of RNA- directed RNA polymerases (Koonin, E. V. and Dolja, V. V. (1993) Crit. Rev. Biochem. Molec.
Biol. 28: 375-430).
The actual roles and functions of the NS proteins of pestiviruses and hepaciviruses in the lifecycle of the viruses are directly analogous. In both cases, the NS3 serine proteinase is responsible for all proteolytic processing of polyprotein precursors downstream of its position in the ORF (Wiskerchen and Collett (1991) Virology 184: 341-350; Bartenschlager et al. (1993) J. Virol. 67: 3835-3844; Eckart et al. (1993) Biochem. Biophys. Res. Comm. 192: 399- 406; Grakoui et al. (1993) J. Virol. 67: 2832-2843; Grakoui et al. (1993) Proc. Natl. Acad.
Sci. USA 90: 10583-10587; Hijikata et al. (1993) J. Virol. 67: 4665-4675; Tome et al. (1993) J. Virol. 67: 4017-4026). The NS4A protein, in both cases, acts as a cofactor with the NS3 serine protease (Bartenschlager et al. (1994) J. Virol. 68: 5045-5055; Failla et al. (1994) J. Virol. 68: 3753-3760; Lin et al. (1994) 68: 8147-8157; Xu et al. (1997) J. Virol. 71: 5312- 5322). The NS3 protein of both viruses also functions as a helicase (Kim et al. (1995) Biochem. Biophys. Res. Comm. 215: 160-166; Jin and Peterson (1995) Arch. Biochem.
Biophys., 323: 47-53; Warrener and Collett (1995) J. Virol. 69: 1720-1726). Finally, the NS5B proteins of pestiviruses and hepaciviruses have the predicted RNA-directed RNA polymerases activity (Behrens et al. (l996) EMBO J. 15: 12-22; Lchmannet al. (l997) J. Virol.
71: 8416-8428; Yuan et al. (1997) Biochem. Biophys. Res. Comm. 232: 231-235; Hagedorn, PCT WO 97/12033; Zhong et al. (1998) J. Virol. 72.9365-9369).
Hepatitis C Virus The hepatitis C virus (HCV) is the leading cause of chronic liver disease worldwide.
(Boyer, N. et al. J. Hepatol. 32: 98-112,2000). HCV causes a slow growing viral infection and is the major cause of cirrhosis and hepatocellular carcinoma (Di Besceglie, A. M. and Bacon, B. R., Scientific American, Oct.: 80-85, (1999); Boyer, N. et al. J. Hepatol. 32: 98- 112,2000). An estimated 170 million persons are infected with HCV worldwide. (Boyer, N. et al. J. Hepatol. 32: 98-112,2000). Cirrhosis caused by chronic hepatitis C infection accounts for 8,000-12, 000 deaths per year in the United States, and HCV infection is the leading indication for liver transplantation.
HCV is known to cause at least 80% of posttransfusion hepatitis and a substantial proportion of sporadic acute hepatitis. Preliminary evidence also implicates HCV in many cases of"idiopathic"chronic hepatitis, "cryptogenic"cirrhosis, and probably hepatocellular carcinoma unrelated to other hepatitis viruses, such as Hepatitis B Virus (HBV). A small proportion of healthy persons appear to be chronic HCV carriers, varying with geography and other epidemiological factors. The numbers may substantially exceed those for HBV, though information is still preliminary; how many of these persons have subclinical chronic liver disease is unclear. (The Merck Manual, ch. 69, p. 901, 16th ed. , (1992)).
HCV is an enveloped virus containing a positive-sense single-stranded RNA genome of approximately 9.4kb. The viral genome consists of a 5'untranslated region (UTR), a long open reading frame encoding a polyprotein precursor of approximately 3011 amino acids, and a short 3'UTR. The 5'UTR is the most highly conserved part of the HCV genome and is important for the initiation and control of polyprotein translation. Translation of the HCV genome is initiated by a cap-independent mechanism known as internal ribosome entry. This mechanism involves the binding of ribosomes to an RNA sequence known as the internal ribosome entry site (IRES). An RNA pseudoknot structure has recently been determined to be an essential structural element of the HCV IRES. Viral structural proteins include a nucleocapsid core protein (C) and two envelope glycoproteins, El and E2. HCV also encodes two proteinases, a zinc-dependent metalloproteinase encoded by the NS2-NS3 region and a serine proteinase encoded in the NS3 region. These proteinases are required for cleavage of specific regions of the precursor polyprotein into mature peptides. The carboxyl half of nonstructural protein 5, NS5B, contains the RNA-dependent RNA polymerase. The function of the remaining nonstructural proteins, NS4A and NS4B, and that of NS5A (the amino-terminal half of nonstructural protein 5) remain unknown.
A significant focus of current antiviral research is directed to the development of improved methods of treatment of chronic HCV infections in humans (Di Besceglie, A. M. and Bacon, B. R., Scientific American, Oct.: 80-85, (1999)).
Treatment of HCV Infection with Interferon Interferons (IFNs) have been commercially available for the treatment of chronic hepatitis for nearly a decade. IFNs are glycoproteins produced by immune cells in response to viral infection. IFNs inhibit replication of a number of viruses, including HCV, and when used as the sole treatment for hepatitis C infection, IFN can in certain cases suppress serum
HCV-RNA to undetectable levels. Additionally, IFN can normalize serum amino transferase levels. Unfortunately, the effect of IFN is temporary and a sustained response occurs in only 8%-9% of patients chronically infected with HCV (Gary L. Davis. Gastroenterology 118: S104-S114, 2000). Most patients, however, have difficulty tolerating interferon treatment, which causes severe flu-like symptoms, weight loss, and lack of energy and stamina.
A number of patents disclose Flaviviridae, including HCV, treatments, using interferon-based therapies. For example, U. S. Patent No. 5,980, 884 to Blatt et al. discloses methods for retreatment of patients afflicted with HCV using consensus interferon. U. S.
Patent No. 5,942, 223 to Bazer et al. discloses an anti-HCV therapy using ovine or bovine interferon-tau. U. S. Patent No. 5,928, 636 to Alber et al. discloses the combination therapy of interleukin-12 and interferon alpha for the treatment of infectious diseases including HCV.
U. S. Patent No. 5,849, 696 to Chretien et al. discloses the use of thymosins, alone or in combination with interferon, for treating HCV. U. S. Patent No. 5,830, 455 to Valtuena et al. discloses a combination HCV therapy employing interferon and a free radical scavenger.
U. S. Patent No. 5,738, 845 to Imakawa discloses the use of human interferon tau proteins for treating HCV. Other interferon-based treatments for HCV are disclosed in U. S. Patent No.
5,676, 942 to Testa et al., U. S. Patent No. 5,372, 808 to Blatt et al., and U. S. Patent No.
5,849, 696. A number of patents also disclose pegylated forms of interferon, such as U. S.
Patent Nos. 5,747, 646,5, 792,834 and 5,834, 594 to Hoffmann-La Roche Inc; PCT Publication No. WO 99/32139 and WO 99/32140 to Enzon; WO 95/13090 and US Patent Nos. 5,738, 846 and 5,711, 944 to Schering; and U. S. Patent No. 5,908, 621 to Glue et al..
Interferon alpha-2a and interferon alpha-2b are currently approved as monotherapy for the treatment of HCV. ROFERON (»-A (Roche) is the recombinant form of interferon alpha-2a. PEGASYS (g) (Roche) is the pegylated (i. e. polyethylene glycol modified) form of interferon alpha-2a. INTRONISA (Schering Corporation) is the recombinant form of Interferon alpha-2b, and PEG-INTRONS (Schering Corporation) is the pegylated form of interferon alpha-2b.
Other forms of interferon alpha, as well as interferon beta, gamma, tau and omega are currently in clinical development for the treatment of HCV. For example, INFERGEN (interferon alphacon-1) by InterMune, OMNIFERON (natural interferon) by Viragen, ALBUFERON by Human Genome Sciences, REBIF (interferon beta-la) by Ares-Serono, Omega Interferon by BioMedicine, Oral Interferon Alpha by Amarillo Biosciences, and
interferon gamma, interferon tau, and interferon gamma-lb by InterMune are in development.
Ribivarin Ribavirin (1-p-D-ribofuranosyl-1-1, 2,4-triazole-3-carboxamide) is a synthetic, non- interferon-inducing, broad spectrum antiviral nucleoside analog sold under the trade name, Virazole (The Merck Index, 1 lth edition, Editor: Budavari, S. , Merck & Co. , Inc. , Rahway, NJ, pl304, 1989). United States Patent No. 3,798, 209 and RE29, 835 disclose and claim ribavirin. Ribavirin is structurally similar to guanosine, and has in vitro activity against several DNA and RNA viruses including Flaviviridae (Gary L. Davis. Gastroenterology 118: S104-S114, 2000).
Ribavirin reduces serum amino transferase levels to normal in 40% of patients, but it does not lower serum levels of HCV-RNA (Gary L. Davis. Gastroenterology 118: S 104-S 114, 2000). Thus, ribavirin alone is not effective in reducing viral RNA levels. Additionally, ribavirin has significant toxicity and is known to induce anemia.
Ribavirin is not approved for monotherapy against HCV. It has been approved in combination with interferon alpha-2a or interferon alpha-2b for the treatment of HCV.
Combination of Interferon and Ribavirin The current standard of care for chronic hepatitis C is combination therapy with an alpha interferon and ribavirin. The combination of interferon and ribavirin for the treatment of HCV infection has been reported to be effective in the treatment of interferon naive patients (Battaglia, A. M. et al., Ann. Pharmacother. 34: 487-494,2000), as well as for treatment of patients when histological disease is present (Berenguer, M. et al. Antivir. Ther.
3 (Suppl. 3): 125-136,1998). Studies have show that more patients with hepatitis C respond to pegylated interferon-alpha/ribavirin combination therapy than to combination therapy with unpegylated interferon alpha. However, as with monotherapy, significant side effects develop during combination therapy, including hemolysis, flu-like symptoms, anemia, and fatigue. (Gary L. Davis. Gastroenterology 118 : S104-S114, 2000).
Combination therapy with PEG-INTRONS (peginterferon alpha-2b) and REBETOL) (Ribavirin, USP) Capsules is available from Schering Corporation.
REBETOLS (Schering Corporation) has also been approved in combination with INTRO
A (Interferon alpha-2b, recombinant, Schering Corporation). Roche's PEGASYSO (pegylated interferon alpha-2a) and COPEGUS (I (ribavirin) are also approved for the treatment of HCV.
PCT Publication Nos. WO 99/59621, WO 00/37110, WO 01/81359, WO 02/32414 and WO 03/024461 by Schering Corporation disclose the use of pegylated interferon alpha and ribavirin combination therapy for the treatment of HCV. PCT Publication Nos. WO 99/15194, WO 99/64016, and WO 00/24355 by Hoffmann-La Roche Inc also disclose the use of pegylated interferon alpha and ribavirin combination therapy for the treatment of HCV.
Additional Methods to Treat Flaviviridae Infections The development of new antiviral agents for flaviviridae infections, especially hepatitis C, is currently underway. Specific inhibitors of HCV-derived enzymes such as protease, helicase, and polymerase inhibitors are being developed. Drugs that inhibit other steps in HCV replication are also in development, for example, drugs that block production of HCV antigens from the RNA (IRES inhibitors), drugs that prevent the normal processing of HCV proteins (inhibitors of glycosylation), drugs that block entry of HCV into cells (by blocking its receptor) and nonspecific cytoprotective agents that block cell injury caused by the virus infection. Further, molecular approaches are also being developed to treat hepatitis C, for example, ribozymes, which are enzymes that break down specific viral RNA molecules, and antisense oligonucleotides, which are small complementary segments of DNA that bind to viral RNA and inhibit viral replication, are under investigation. A number of HCV treatments are reviewed by Bymock et al. in Antiviral Chemistry & Chemotherapy, 11: 2; 79-95 (2000) and De Francesco et al. in Antiviral Research, 58 : 1-16 (2003).
Examples of classes of drugs that are being developed to treat Flaviviridae infections include: (1) Protease inhibitors Substrate-based NS3 protease inhibitors (Attwood et al., Antiviral peptide derivatives, PCT WO 98/22496,1998 ; Attwood et al., Antiviral Chemistry and Chemotherapy 1999, 10, 259-273; Attwood et al., Preparation and use of amino acid derivatives as anti-viral agents, German Patent Pub. DE 19914474; Tung et al. Inhibitors of serine proteases, particularly
hepatitis C virus NS3 protease, PCT WO 98/17679), including alphaketoamides and hydrazinoureas, and inhibitors that terminate in an electrophile such as a boronic acid or phosphonate (Llinas-Brunet et al, Hepatitis C inhibitor peptide analogues, PCT WO 99/07734) are being investigated.
Non-substrate-based NS3 protease inhibitors such as 2,4, 6-trihydroxy-3-nitro- benzamide derivatives (Sudo K. et al., Biochemical and Biophysical Research Communications, 1997, 238, 643-647; Sudo K. et al. Antiviral Chemistry and Chemotherapy, 1998, 9, 186), including RD3-4082 and RD3-4078, the former substituted on the amide with a 14 carbon chain and the latter processing a para-phenoxyphenyl group are also being investigated.
Sch 68631, a phenanthrenequinone, is an HCV protease inhibitor (Chu M. et al., Tetrahedron Letters 37: 7229-7232,1996). In another example by the same authors, Sch 351633, isolated from the fungus Penicillium griseofulvum, was identified as a protease inhibitor (Chu M. et al., Bioorganic and Medicinal Chemistry Letters 9: 1949-1952).
Nanomolar potency against the HCV NS3 protease enzyme has been achieved by the design of selective inhibitors based on the macromolecule eglin c. Eglin c, isolated from leech, is a potent inhibitor of several serine proteases such as S. griseus proteases A and B, a- chymotrypsin, chymase and subtilisin. Qasim M. A. et al., Biochemistry 36 : 1598-1607,1997.
Several U. S. patents disclose protease inhibitors for the treatment of HCV. For example, U. S. Patent No. 6,004, 933 to Spruce et al. discloses a class of cysteine protease inhibitors for inhibiting HCV endopeptidase 2. U. S. Patent No. 5,990, 276 to Zhang et al. discloses synthetic inhibitors of hepatitis C virus NS3 protease. The inhibitor is a subsequence of a substrate of the NS3 protease or a substrate of the NS4A cofactor. The use of restriction enzymes to treat HCV is disclosed in U. S. Patent No. 5,538, 865 to Reyes et al.
Peptides as NS3 serine protease inhibitors of HCV are disclosed in WO 02/008251 to Corvas International, Inc, and WO 02/08187 and WO 02/008256 to Schering Corporation. HCV inhibitor tripeptides are disclosed in US Patent Nos. 6,534, 523,6, 410,531, and 6,420, 380 to Boehringer Ingelheim and WO 02/060926 to Bristol Myers Squibb. Diaryl peptides as NS3 serine protease inhibitors of HCV are disclosed in WO 02/48172 to Schering Corporation.
Imidazoleidinones as NS3 serine protease inhibitors of HCV are disclosed in WO 02/08198 to Schering Corporation and WO 02/48157 to Bristol Myers Squibb. WO 98/17679 to Vertex Pharmaceuticals and WO 02/48116 to Bristol Myers Squibb also disclose HCV protease inhibitors.
(2) Thiazolidine derivatives which show relevant inhibition in a reverse-phase HPLC assay with an NS3/4A fusion protein and NS5A/5B substrate (Sudo K. et al., Antiviral Research, 1996,32, 9-18), especially compound RD-1-6250, possessing a fused cinnamyl moiety substituted with a long alkyl chain, RD4 6205 and RD4 6193; (3) Thiazolidines and benzanilides identified in Kakiuchi N. et al. J. EBS Letters 421, 217-220; Takeshita N. et al. Analytical Biochemistry, 1997, 247, 242-246; (4) A phenan-threnequinone possessing activity against protease in a SDS-PAGE and autoradiography assay isolated from the fermentation culture broth of Streptomyces sp. , Sch 68631 (Chu M. et al., Tetrahedron Letters, 1996,37, 7229-7232), and Sch 351633, isolated from the fungus Penicillium griseofulvum, which demonstrates activity in a scintillation proximity assay (Chu M. et al., Bioorganic and Medicinal Chemistry Letters 9, 1949-1952); (5) Helicase inhibitors (Diana G. D. et al., Compounds, compositions and methods for treatment of hepatitis C, U. S. Pat. No. 5,633, 358; Diana G. D. et al., Piperidine derivatives, pharmaceutical compositions thereof and their use in the treatment of hepatitis C, PCT WO 97/36554); (6) Nucleotide polymerase inhibitors and gliotoxin (Ferrari R. et al. Journal of Virology, 1999,73, 1649-1654), and the natural product cerulenin (Lohmann V. et al., Virology, 1998, 249, 108-118); (7) Antisense phosphorothioate oligodeoxynucleotides (S-ODN) complementary to sequence stretches in the 5'non-coding region (NCR) of the virus (Alt M. et al., Hepatology, 1995,22, 707-717), or nucleotides 326-348 comprising the 3'end of the NCR and nucleotides 371-388 located in the core coding region of the HCV RNA (Alt M. et al., Archives of Virology, 1997, 142, 589-599; Galderisi U. et al., Journal of Cellular Physiology, 1999, 181, 251-257);
(8) Inhibitors of IRES-dependent translation (Ikeda N et al., Agent for the prevention and treatment of hepatitis C, Japanese Patent Pub. JP-08268890; Kai Y. et al.
Prevention and treatment of viral diseases, Japanese Patent Pub. JP-10101591); (9) Ribozymes, such as nuclease-resistant ribozymes (Maccjak, D. J. et al., Hepatology 1999,30, abstract 995) and those disclosed in U. S. Patent No.
6,043, 077 to Barber et al., and U. S. Patent Nos. 5,869, 253 and 5,610, 054 to Draper et al. ; and (10) Nucleoside analogs have also been developed for the treatment of Flaviviridae infections.
Idenix Pharmaceuticals discloses the use of branched in the treatment of flaviviruses (including HCV) and pestiviruses in International Publication Nos. WO 01/90121 and WO 01/92282. Specifically, a method for the treatment of hepatitis C infection (and flaviviruses and pestiviruses) in humans and other host animals is disclosed in the Idenix publications that includes administering an effective amount of a biologically active 1', 2', 3'or 4'-branched ß-D or P-L nucleosides or a pharmaceutically acceptable salt or derivative thereof, administered either alone or in combination with another antiviral agent, optionally in a pharmaceutically acceptable carrier.
Other patent applications disclosing the use of certain nucleoside analogs to treat hepatitis C virus include: PCT/CA00/01316 (WO 01/32153 ; filed November 3,2000) and PCT/CA01/00197 (WO 01/60315 ; filed February 19,2001) filed by BioChem Pharma, Inc.
(now Shire Biochem, Inc. ) ; PCT/US02/01531 (WO 02/057425; filed January 18,2002) and PCT/US02/03086 (WO 02/057287; filed January 18,2002) filed by Merck & Co. , Inc., PCT/EP01/09633 (WO 02/18404; published August 21,2001) filed by Roche, and PCT Publication Nos. WO 01/79246 (filed April 13,2001), WO 02/32920 (filed October 18, 2001) and WO 02/48165 by Pharmasset, Ltd.
PCT Publication No. WO 99/43691 to Emory University, entitled"2'- Fluoronucleosides"discloses the use of certain 2'-fluoronucleosides to treat HCV.
Eldrup et al. (Oral Session V, Hepatitis C Virus, Flaviviridae; 16"'International Conference on Antiviral Research (April 27,2003, Savannah, Ga. )) described the structure activity relationship of 2'-modified nucleosides for inhibition of HCV.
Bhat et al. (Oral Session V, Hepatitis C Virus, Flaviviridae, 2003 (Oral Session V, Hepatitis C Virus, Flaviviridae ; 16th International Conference on Antiviral Research (April 27,2003, Savannah, Ga.) ; p A75) describe the synthesis and pharmacokinetic properties of nucleoside analogues as possible inhibitors of HCV RNA replication. The authors report that 2'-modified nucleosides demonstrate potent inhibitory activity in cell-based replicon assays.
Olsen et al. (Oral Session V, Hepatitis C Virus, Flaviviridae ; 16th International Conference on Antiviral Research (April 27,2003, Savannah, Ga. ) p A76) also described the effects of the 2'-modified nucleosides on HCV RNA replication.
(11) Other miscellaneous compounds including 1-amino-alkylcyclohexanes (U. S.
Patent No. 6,034, 134 to Gold et al.), alkyl lipids (U. S. Pat. No. 5,922, 757 to Chojkier et al.), vitamin E and other antioxidants (U. S. Pat. No. 5,922, 757 to Chojkier et al.), squalene, amantadine, bile acids (U. S. Pat. No. 5,846, 964 to Ozeki et al.), N- (phosphonoacetyl)-L- aspartic acid, (U. S. Pat. No. 5,830, 905 to Diana et al.), benzenedicarboxamides (U. S. Pat. No.
5,633, 388 to Diana et al.), polyadenylic acid derivatives (U. S. Pat. No. 5,496, 546 to Wang et al.), 2', 3'-dideoxyinosine (U. S. Pat. No. 5,026, 687 to Yarchoan et al.), benzimidazoles (U. S.
Pat. No. 5,891, 874 to Colacino et al.), plant extracts (U. S. Patent No. 5,837, 257 to Tsai et al., U. S. Patent No. 5,725, 859 to Omer et al., and U. S. Patent No. 6,056, 961), and piperidenes (U. S. Patent No. 5,830, 905 to Diana et al.).
(12) Other compounds currently in preclinical or clinical development for treatment of hepatitis C virus include: Interleukin-10 by Schering-Plough, IP-501 by Interneuron, Merimebodib (VX-497) by Vertex, AMANTADINES (Symmetrel) by Endo Labs Solvay, HEPTAZYMEO by RPI, IDN-6556 by Idun Pharma. , XTL-002 by XTL., HCV/MF59 by Chiron, CIVACIRO (Hepatitis C Immune Globulin) by NABI, LEVOVIRINS by ICN/Ribapharm, VIRAMIDINE (S) by ICN/Ribapharm, ZADAXIN) (thymosin alpha-1) by Sci Clone, thymosin plus pegylated interferon by Sci Clone, CEPLENE) (histamine dihydrochloride) by Maxim, VX 950/LY 570310 by Vertex/Eli Lilly, ISIS 14803 by Isis Pharmaceutical/Elan, IDN-6556 by Idun Pharmaceuticals, Inc. , JTK 003 by AKROS Pharma, BILN-2061 by Boehringer Ingelheim, CellCept (mycophenolate mofetil) by Roche, T67, a p-tubulin inhibitor, by Tularik, a therapeutic vaccine directed to E2 by Innogenetics, FK788 by Fujisawa Healthcare, Inc. , IdB 1016 (Siliphos, oral silybin- phosphatdylcholine phytosome), RNA replication inhibitors (VP50406) by ViroPharma/Wyeth, therapeutic vaccine by Intercell, therapeutic vaccine by
Epimmune/Genencor, IRES inhibitor by Anadys, ANA 245 and ANA 246 by Anadys, immunotherapy (Therapore) by Avant, protease inhibitor by Corvas/SChering, helicase inhibitor by Vertex, fusion inhibitor by Trimeris, T cell therapy by CellExSys, polymerase inhibitor by Biocryst, targeted RNA chemistry by PTC Therapeutics, Dication by Immtech, Int. , protease inhibitor by Agouron, protease inhibitor by Chiron/Medivir, antisense therapy by AVI BioPharma, antisense therapy by Hybridon, hemopurifier by Aethlon Medical, therapeutic vaccine by Merix, protease inhibitor by Bristol-Myers Squibb/Axys, Chron- VacC, a therapeutic vaccine, by Tripep, UT 231B by United Therapeutics, protease, helicase and polymerase inhibitors by Genelabs Technologies, IRES inhibitors by Immusol, R803 by Rigel Pharmaceuticals, INFERGENS (interferon alphacon-1) by InterMune, OMNIFERON) (natural interferon) by Viragen, ALBUFERONS by Human Genome Sciences, REBIF) (interferon beta-la) by Ares-Serono, Omega Interferon by BioMedicine, Oral Interferon Alpha by Amarillo Biosciences, interferon gamma, interferon tau, and Interferon gamma-1 b by InterMune.
Nucleoside prodrugs have been previously described for the treatment of other forms of hepatitis. WO 00/09531 (filed August 10,1999) and WO 01/96353 (filed June 15,2001) to Idenix Pharmaceuticals, discloses 2'-deoxy-p-L-nucleosides and their 3'-prodrugs for the treatment of HBV. U. S. Patent No. 4,957, 924 to Beauchamp discloses various therapeutic esters of acyclovir.
In light of the fact that HCV infection has reached epidemic levels worldwide, and has tragic effects on the infected patient, there remains a strong need to provide new effective pharmaceutical agents to treat hepatitis C that have low toxicity to the host.
Further, given the rising threat of other flaviviridae infections, there remains a strong need to provide new effective pharmaceutical agents that have low toxicity to the host.
Therefore, it is an object of the present invention to provide a compound, method and composition for the treatment of a host infected with flaviviridae, including hepatitis C virus.
It is another object of the present invention to provide a compound, method and composition generally for the treatment of patients infected with pestiviruses, flaviviruses, or hepaciviruses.
SUMMARY OF THE INVENTION 2'-and 3'-prodrugs of 1', 2', 3'or 4'-branched 3-D or R-L nucleosides, or their pharmaceutically acceptable salts, or pharmaceutically acceptable formulations containing these compounds are useful in the prevention and treatment of Flaviviridae infections and other related conditions such as anti-Flaviviridae antibody positive and Flaviviridae-positive conditions, chronic liver inflammation caused by HCV, cirrhosis, acute hepatitis, fulminant hepatitis, chronic persistent hepatitis, and fatigue. These compounds or formulations can also be used prophylactically to prevent or retard the progression of clinical illness in individuals who are anti-Flaviviridae antibody or Flaviviridae-antigen positive or who have been exposed to a Flaviviridae. In one specific embodiment, the Flaviviridae is hepatitis C. In an alternative embodiment, the compound is used to treat any virus that replicates through an RNA-dependent RNA polymerase.
A method for the treatment of a Flaviviridae infection in a host, including a human, is also disclosed that includes administering an effective amount of a 2'-or 3'-prodrug of a biologically active 1', 2', 3'or 4'-branched ß-D or ß-L nucleosides or a pharmaceutically acceptable salt thereof, administered either alone or in combination or alternation with another anti-Flaviviridae agent, optionally in a pharmaceutically acceptable carrier. The term 1', 2', 3'or 4'-branched, as used in this specification, refers to a nucleoside that has an additional non-natural substituent in the 1', 2', 3'or 4'-position (i. e. , carbon is bound to four nonhydrogen substituents). The term 2'-prodrug, as used herein, refers to a 1', 2', 3'or 4'- branched P-D or P-L nucleoside that has a biologically cleavable moiety at the 2'-position, including, but not limited to acyl, and in one embodiment, a natural or synthetic L-or D- amino acid, preferably an L-amino acid. The term 3'-prodrug, as used herein, refers to a 1', 2', 3'or 4'-branched ß-D or ß-L nucleoside that has a biologically cleavable moiety at the 3'- position, including, but not limited to acyl, and in one embodiment, a natural or synthetic L- or D-amino acid, preferably an L-amino acid. Certain other alternative embodiments are also included.
In one embodiment, the prodrug of 1', 2', 3'or 4'-branched ß-D or ß-L nucleoside includes biologically cleavable moieties at the 2'and/or 5'positions. Preferred moieties are natural or synthetic D or L amino acid esters, including D or L-valyl, though preferably L- amino acid esters, such as L-valyl, and alkyl esters including acetyl. Therefore, this invention specifically includes 2'-L or D-amino acid ester and 2', 5'-L or D-diamino acid ester of 1', 2',
3'or 4'-branched P-D or ß-L nucleosides, preferably L-amino acid, with any desired purine or pyrimidine base, wherein the parent drug optionally has an EC50 of less than 15 micromolar, and even more preferably less than 10 micromolar; 2'- (alkyl or aryl) ester or 2', 5'-L-di (alkyl or aryl) ester of 1', 2', 3'or 4'-branched ß-D or ß-L nucleosides with any desired purine or pyrimidine base, wherein the parent drug optionally has an EC50 of less than 10 or 15 micromolar; and prodrugs of 2', 5'-diesters of 1', 2', 3'or 4'-branched ß-D or P-L nucleosides wherein (i) the 2'ester is an amino acid ester and the 5'-ester is an alkyl or aryl ester; (ii) both esters are amino acid esters; (iii) both esters are independently alkyl or aryl esters; and (iv) the 2'ester is independently an alkyl or aryl ester and the 5'-ester is an amino acid ester, wherein the parent drug optionally has an EC50 of less than 10 or 15 micromolar.
Examples of prodrugs falling within the invention are 2'-L-valine ester of P-D-2'- methyl-cytidine; 2'-L-valine ester of ß-D-2'-methyl-thymidine ; 2'-L-valine ester of ß-D-2'- methyl-adenosine; 2'-L-valine ester of ß-D-2'-methyl-guanosine ; 2'-L-valine ester of (3-D-2'- methyl-5-fluorocytidine ; 2'-L-valine ester of ß-D-2'-methyl-uridine ; 2'-acetyl ester of P-D- 2'-methyl-cytidine ; 2'-acetyl ester of P-D-2'-methyl-thymidine ; 2'-acetyl ester of ß-D-2'- methyl-adenosine ; 2'-acetyl ester of ß-D-2'-methyl-guanosine ; 2'-acetyl ester of P-D-2'- methyl-5-fluoro-cytidine; and 2'-esters of P-D-2'-methyl- (cytidine, 5-fluorocytidine, guanosine, uridine, adenosine, or thymidine) wherein (i) the 2'ester is an amino acid ester; or (ii) the 2'ester is an alkyl or aryl ester.
Additional examples of prodrugs falling within the invention are 2', 5'-L-divaline ester of (3-D-2'-methyl-cytidine (dival-2'-Me-L-dC) ; 2', 5'-L-divaline ester of ß-D-2'-methyl- thymidine; 2', 5'-L-divaline ester of ß-D-2'-methyl-adenosine ; 2', 5'-L-divaline ester of ß-D- 2'-methyl-guanosine; 2', 5'-L-divaline ester of ß-D-2'-methyl-5-fluoro-cytidine ; 2', 5'-L- divaline ester of ß-D-2'-methyl-uridine ; 2', 5'-diacetyl ester of ß-D-2'-methyl-cytidine ; 2', 5'- diacetyl ester of ß-D-2'-methyl-thymidine ; 2', 5'-diacetyl ester of P-D-2'-methyl-adenosine ; 2', 5'-diacetyl ester of ß-D-2'-methyl-guanosine ; 2', 5'-diacetyl ester of P-D-2'-methyl-5- fluoro-cytidine; and 2', 5'-diesters of ß-D-2'-methyl-(cytidine, 5-fluorocytidine, guanosine, uridine, adenosine, or thymidine) wherein (i) the 2'ester is an amino acid ester and the 5'- ester is an alkyl or aryl ester; (ii) both esters are amino acid esters; (iii) both esters are independently alkyl or aryl esters; or (iv) the 2'ester is an alkyl or aryl ester and the 5'-ester is an amino acid ester.
In another embodiment, the prodrug of 1', 2', 3'or 4'-branched P-D or P-L nucleoside includes biologically cleavable moieties at the 3'and/or 5'positions. Preferred moieties are natural or synthetic D or L amino acid esters, including D or L-valyl, though preferably L- amino acid esters, such as L-valyl, and alkyl esters including acetyl. Therefore, this invention specifically includes 3'-L or D-amino acid ester and 3', 5'-L or D-diamino acid ester of 1', 2', 3'or 4'-branched P-D or ß-L nucleosides, preferably L-amino acid, with any desired purine or pyrimidine base, wherein the parent drug optionally has an EC50 of less than 15 micromolar, and even more preferably less than 10 micromolar ; 3'- (alkyl or aryl) ester or 3', 5'-L-di (alkyl or aryl) ester of 1', 2', 3'or 4'-branched ß-D or ß-L nucleosides with any desired purine or pyrimidine base, wherein the parent drug optionally has an EC50 of less than 10 or 15 micromolar ; and prodrugs of 3', 5'-diesters of 1', 2', 3'or 4'-branched P-D or P-L nucleosides wherein (i) the 3'ester is an amino acid ester and the 5'-ester is an alkyl or aryl ester; (ii) both esters are amino acid esters; (iii) both esters are independently alkyl or aryl esters; and (iv) the 3'ester is independently an alkyl or aryl ester and the 5'-ester is an amino acid ester, wherein the parent drug optionally has an EC50 of less than 10 or 15 micromolar.
Examples of prodrugs falling within the invention are 3'-L-valine ester of (3-D-2'- methyl-cytidine; 3'-L-valine ester of ß-D-2'-methyl-thymidine ; 3'-L-valine ester of ß-D-2'- methyl-adenosine; 3'-L-valine ester of ß-D-2'-methyl-guanosine ; 3'-L-valine ester of (3-D-2'- methyl-5-fluorocytidine; 3'-L-valine ester of ß-D-2'-methyl-uridine ; 3'-acetyl ester of ß-D- 2'-methyl-cytidine; 3'-acetyl ester of ß-D-2'-methyl-thymidine ; 3'-acetyl ester of ß-D-2'- methyl-adenosine; 3'-acetyl ester of ß-D-2'-methyl-guanosine ; 3'-acetyl ester of P-D-2'- methyl-5-fluoro-cytidine; and 3'-esters of ß-D-2'-methyl-(cytidine, 5-fluorocytidine, guanosine, uridine, adenosine, or thymidine) wherein (i) the 3'ester is an amino acid ester; or (ii) the 3'ester is an alkyl or aryl ester.
Additional examples of prodrugs falling within the invention are 3', 5'-L-divaline ester of ß-D-2'-methyl-cytidine (dival-2'-Me-L-dC) ; 3', 5'-L-divaline ester of ß-D-2'-methyl- thymidine; 3', 5'-L-divaline ester of ß-D-2'-methyl-adenosine ; 3', 5'-L-divaline ester of ß-D- 2'-methyl-guanosine ; 3', 5'-L-divaline ester of ß-D-2'-methyl-5-fluoro-cytidine ; 3', 5'-L- divaline ester of ß-D-2'-methyl-uridine ; 3', 5'-diacetyl ester of ß-D-2'-methyl-cytidine ; 3', 5'- diacetyl ester of ß-D-2'-methyl-thymidine ; 3', 5'-diacetyl ester of ß-D-2'-methyl-adenosine ; 3', 5'-diacetyl ester of ß-D-2'-methyl-guanosine ; 3', 5'-diacetyl ester of P-D-2'-methyl-5- fluoro-cytidine; and 3', 5'-diesters of ß-D-2'-methyl-(cytidine, 5-fluorocytidine, guanosine,
uridine, adenosine, or thymidine) wherein (i) the 3'ester is an amino acid ester and the 5'- ester is an alkyl or aryl ester; (ii) both esters are amino acid esters; (iii) both esters are independently alkyl or aryl esters; or (iv) the 3'ester is an alkyl or aryl ester and the 5'-ester is an amino acid ester.
In another embodiment, the prodrug of 1', 2', 3'or 4'-branched ß-D or ß-L nucleoside includes biologically cleavable moieties at the 2', 3'and/or 5'positions. Preferred moieties are D or L amino acid esters, including D or L-valyl, though preferably L-amino acid esters, such as L-valyl, and alkyl esters including acetyl. Therefore, this invention specifically includes 2', 3'-L or D-diamino acid ester and 2', 3', 5'-L or D-triamino acid ester of 1', 2', 3' or 4'-branched ß-D or P-L nucleosides, preferably L-amino acid, with any desired purine or pyrimidine base, wherein the parent drug optionally has an EC50 of less than 15 micromolar, and even more preferably less than 10 micromolar; 2', 3'-di (alkyl or aryl) ester or 2', 3', 5'-L- tri (alkyl or aryl) ester of 1', 2', 3'or 4'-branched P-D or ß-L nucleosides with any desired purine or pyrimidine base, wherein the parent drug optionally has an ECso of less than 10 or 15 micromolar; and prodrugs of 2', 3'-diesters of 1', 2', 3'or 4'-branched P-D or ß-L nucleosides wherein (i) the 2'ester is an amino acid ester and the 3'-ester is an alkyl or aryl ester; (ii) both esters are amino acid esters; (iii) both esters are independently alkyl or aryl esters; and (iv) the 2'ester is independently an alkyl or aryl ester and the 3'-ester is an amino acid ester, wherein the parent drug optionally has an EC50 of less than 10 or 15 micromolar.
Further, 2', 3', 5'-triesters of 1', 2', 3'or 4'-branched ß-D or ß-L nucleosides wherein (i) all three esters are amino acid esters; (ii) all three esters are independently alkyl or aryl esters; (iii) the 2'ester is an amino acid ester, the 3'ester is an amino acid ester and the 5'-ester is an alkyl or aryl ester; (iv) the 2'ester is an amino acid ester, the 3'ester is an alkyl or aryl ester and the 5'-ester is an alkyl or aryl ester; (v) the 2'ester is an alkyl or aryl ester, the 3'ester is an alkyl or aryl ester and the 5'-ester is an amino acid ester; (vi) the 2'ester is an alkyl or aryl ester, the 3'ester is an amino acid ester and the 5'-ester is an amino acid ester; (vii) the 2' ester is an alkyl or aryl ester, the 3'ester is an amino acid ester and the 5'-ester is an alkyl or aryl ester; and (viii) the 2'ester is an amino acid ester, the 3'ester is an alkyl or aryl ester and the 5'-ester is an amino acid ester; wherein the parent drug optionally has an EC50 of less than 10 or 15 micromolar.
Examples of prodrugs falling within the invention include 2', 3'-L-divaline ester of D-2'-methyl-cytidine (dival-2'-Me-L-dC); 2', 3'-L-divaline ester of P-D-2'-methyl- thymidine; 2', 3'-L-divaline ester of ß-D-2'-methyl-adenosine ; 2', 3'-L-divaline ester of (3-D-
2'-methyl-guanosine ; 2', 3'-L-divaline ester of P-D-2'-methyl-5-fluoro-cytidine ; 2', 3'-L- divaline ester of ß-D-2'-methyl-uridine ; 2', 3'-diacetyl ester of !-cytidine ; 2', 3'- diacetyl ester of ß-D-2'-methyl-thymidine ; 2', 3'-diacetyl ester of P-D-2'-methyl-adenosine ; 2', 3'-diacetyl ester of ß-D-2'-methyl-guanosine ; 2', 3'-diacetyl ester of ß-D-2'-methyl-5- fluoro-cytidine ; and 2', 3'-diesters of p-D-2'-methyi- (cytidine, 5-ftuorocytidine, guanosine, uridine, adenosine, or thymidine) wherein (i) the 2'ester is an amino acid ester and the 3'- ester is an alkyl or aryl ester; (ii) both esters are amino acid esters; (iii) both esters are independently alkyl or aryl esters; or (iv) the 2'ester is an alkyl or aryl ester and the 3'-ester is an amino acid ester.
Additional examples of prodrugs falling within the invention include 2', 3', 5'-L- trivaline ester of ß-D-2'-methyl-cytidine (trival-2'-Me-L-dC) ; 2', 3', 5'-L-trivaline ester of 0- D-2'-methyl-thymidine ; 2', 3', 5'-L-trivaline ester of ß-D-2'-methyl-adenosine ; 2', 3', 5'-L- trivaline ester of ß-D-2'-methyl-guanosine ; 2', 3', 5'-L-trivaline ester of ß-D-2'-methyl-5- fluoro-cytidine ; 2', 3', 5'-L-trivaline ester of ß-D-2'-methyl-uridine ; 2', 3', 5'-triacetyl ester of ß-D-2'-methyl-cytidine ; 2', 3', 5'-triacetyl ester of ß-D-2'-methyl-thymidine ; 2', 3', 5'-triacetyl ester of P-D-2'-methyl-adenosine ; 2', 3', 5'-triacetyl ester of ß-D-2'-methyl-guanosine ; 2', 3', 5'-triacetyl ester of ß-D-2'-methyl-5-fluoro-cytidine ; and 2', 3', 5'-triesters of P-D-2'- methyl- (cytidine, 5-fluorocytidine, guanosine, uridine, adenosine, or thymidine) wherein (i) all three esters are amino acid esters; (ii) all three esters are independently alkyl or aryl esters; (iii) the 2'ester is an amino acid ester, the 3'ester is an amino acid ester and the 5'-ester is an alkyl or aryl ester; (iv) the 2'ester is an amino acid ester, the 3'ester is an alkyl or aryl ester and the 5'-ester is an alkyl or aryl ester; (v) the 2'ester is an alkyl or aryl ester, the 3'ester is an alkyl or aryl ester and the 5'-ester is an amino acid ester; (vi) the 2'ester is an alkyl or aryl ester, the 3'ester is an amino acid ester and the 5'-ester is an amino acid ester; (vii) the 2' ester is an alkyl or aryl ester, the 3'ester is an amino acid ester and the 5'-ester is an alkyl or aryl ester; and (viii) the 2'ester is an amino acid ester, the 3'ester is an alkyl or aryl ester and the 5'-ester is an amino acid ester.
Pharmaceutically acceptable salts of tosylat, methanesulfonate, acetate, citrate, malonate, tartarate, succinate, benzoate, ascorbate, a-ketoglutarate, and a-glycerophosphate, formate, fumarate, propionate, glycolate, lactate, pyruvate, oxalate, maleate, salicyate, sulfate, sulfonate, nitrate, bicarbonate, hydrobromate, hydrobromide, hydroiodide, carbonate, and phosphoric acid salts are provided. A particularly preferred embodiment is the mono or dihydrochloride pharmaceutically acceptable salts.
In a first principal embodiment, a compound of Formula (I), or a pharmaceutically acceptable salt or prodrug thereof, is provided:
wherein: R', R2 and R3 are independently H, phosphate (including mono-, di-or triphosphate and a stabilized phosphate); straight chained, branched or cyclic alkyl (including lower alkyl) ; acyl (including lower acyl) ; CO-alkyl, CO-aryl, CO-alkoxyalkyl, CO-aryloxyalkyl, CO- substituted aryl, sulfonate ester including alkyl or arylalkyl sulfonyl including methanesulfonyl and benzyl, wherein the phenyl group is optionally substituted with one or more substituents as described in the definition of aryl given herein; alkylsulfonyl, arylsulfonyl, aralkylsulfonyl, a lipid, including a phospholipid; an amino acid; and amino acid residue, a carbohydrate; a peptide; cholesterol ; or other pharmaceutically acceptable leaving group which is capable of providing a compound wherein Rl, R2 and/or R3 is independently H or phosphate, for example when administered in vivo ; wherein at least one of R2 and R3 is not hydrogen; Y is hydrogen, bromo, chloro, fluoro, iodo, OH, OR\ NH, NHR5, NR4R5, SH and SR4 ; Xl and x2 are independently selected from the group consisting of H, straight chained, branched or cyclic alkyl, CO-alkyl, CO-aryl, CO-alkoxyalkyl, chloro, bromo, fluoro, iodo, OH, OR4, NH, NHR5, NR4R5, SH and SR4 ; and R4 and R5 are independently hydrogen, acyl (including lower acyl), or alkyl (including but not limited to methyl, ethyl, propyl and cyclopropyl).
In the embodiments described herein, R', R2 and/or R3 can independently be a pharmaceutically acceptable leaving group which is capable of providing a compound wherein Rl, R2 and/or R3 is independently H or phosphate (including mono-, di-or triphosphate), for example when administered in vivo.
In a second principal embodiment, a compound of Formula II, or a pharmaceutically acceptable salt or prodrug thereof, is provided:
wherein: R', R2 and R3 are independently H, phosphate (including mono-, di-or triphosphate and a stabilized phosphate); straight chained, branched or cyclic alkyl (including lower alkyl) ; acyl (including lower acyl) ; CO-alkyl, CO-aryl, CO-alkoxyalkyl, CO-aryloxyalkyl, CO- substituted aryl, sulfonate ester including alkyl or arylalkyl sulfonyl including methanesulfonyl and benzyl, wherein the phenyl group is optionally substituted with one or more substituents as described in the definition of aryl given herein; alkylsulfonyl, arylsulfonyl, aralkylsulfonyl, a lipid, including a phospholipid; an amino acid; and amino acid residue, a carbohydrate; a peptide; cholesterol ; or other pharmaceutically acceptable leaving group which when administered in vivo is capable of providing a compound wherein Rl, R2 and/or R3 is independently H or phosphate; wherein at least one of R2 and R3 is not hydrogen; Y is hydrogen, bromo, chloro, fluoro, iodo, OR4, NR4R5 or SR4 ; Xl and x2 are independently selected from the group consisting of H, straight chained, branched or cyclic alkyl, CO-alkyl, CO-aryl, CO-alkoxyalkyl, chloro, bromo, fluoro, iodo, oR4 NR4NR5 or SR5 ; and R4 and R5 are independently hydrogen, acyl (including lower acyl), or alkyl (including but not limited to methyl, ethyl, propyl and cyclopropyl).
In a third principal embodiment, a compound of Formula III, or a pharmaceutically acceptable salt or prodrug thereof, is provided:
wherein: R', R2 and R3 are independently H, phosphate (including mono-, di-or triphosphate and a stabilized phosphate); straight chained, branched or cyclic alkyl (including lower alkyl) ; acyl (including lower acyl) ; CO-alkyl, CO-aryl, CO-alkoxyalkyl, CO-aryloxyalkyl, CO- substituted aryl, sulfonate ester including alkyl or arylalkyl sulfonyl including methanesulfonyl and benzyl, wherein the phenyl group is optionally substituted with one or more substituents as described in the definition of aryl given herein; alkylsulfonyl, arylsulfonyl, aralkylsulfonyl, a lipid, including a phospholipid; an amino acid; and amino acid residue, a carbohydrate; a peptide; cholesterol ; or other pharmaceutically acceptable leaving group which when administered in vivo is capable of providing a compound wherein R', R2 and/or R3 is independently H or phosphate; wherein at least one of R2 and R3 is not hydrogen; Y is hydrogen, bromo, chloro, fluoro, iodo, OR4, NR4R5 or SR4 ; Xl and x2 are independently selected from the group consisting of H, straight chained, branched or cyclic alkyl, CO-alkyl, CO-aryl, CO-alkoxyalkyl, chloro, bromo, fluoro, iodo, OR4, NR4NR5 or SR5 ; and R4 and R5 are independently hydrogen, acyl (including lower acyl), or alkyl (including but not limited to methyl, ethyl, propyl and cyclopropyl).
In a fourth principal embodiment, a compound of Formula IV, or a pharmaceutically acceptable salt or prodrug thereof, is provided:
wherein: R', R2 and R3 are independently H, phosphate (including mono-, di-or triphosphate and a stabilized phosphate); straight chained, branched or cyclic alkyl (including lower alkyl) ; acyl (including lower acyl) ; CO-alkyl, CO-aryl, CO-alkoxyalkyl, CO-aryloxyalkyl, CO- substituted aryl, sulfonate ester including alkyl or arylalkyl sulfonyl including methanesulfonyl and benzyl, wherein the phenyl group is optionally substituted with one or more substituents as described in the definition of aryl given herein; alkylsulfonyl, arylsulfonyl, aralkylsulfonyl, a lipid, including a phospholipid ; an amino acid; and amino acid residue, a carbohydrate; a peptide; cholesterol ; or other pharmaceutically acceptable leaving group which when administered in vivo is capable of providing a compound wherein R', R2 and/or R3 is independently H or phosphate; wherein at least one of R2 and R3 is not hydrogen ; Y is hydrogen, bromo, chloro, fluoro, iodo, OR, NR4R5 or SR4 ; Xi vis selected from the group consisting of H, straight chained, branched or cyclic alkyl, CO- alkyl, CO-aryl, CO-alkoxyalkyl, chloro, bromo, fluoro, iodo, OR4, NR4NR5 or SR' ; and R4 and R5 are independently hydrogen, acyl (including lower acyl), or alkyl (including but not limited to methyl, ethyl, propyl and cyclopropyl).
In a fifth principal embodiment, a compound of Formula V, or a pharmaceutically acceptable salt or prodrug thereof, is provided:
wherein: R', R2 and R3 are independently H, phosphate (including mono-, di-or triphosphate and a stabilized phosphate); straight chained, branched or cyclic alkyl (including lower alkyl) ; acyl (including lower acyl) ; CO-alkyl, CO-aryl, CO-alkoxyalkyl, CO-aryloxyalkyl, CO- substituted aryl, sulfonate ester including alkyl or arylalkyl sulfonyl including methanesulfonyl and benzyl, wherein the phenyl group is optionally substituted with one or more substituents as described in the definition of aryl given herein; alkylsulfonyl, arylsulfonyl, aralkylsulfonyl, a lipid, including a phospholipid ; an amino acid; and amino acid residue, a carbohydrate; a peptide; cholesterol; or other pharmaceutically acceptable leaving group which when administered in vivo is capable of providing a compound wherein R', R2 and/or R3 is independently H or phosphate; wherein at least one of R2 and R3 is not hydrogen; Y is hydrogen, bromo, chloro, fluoro, iodo, OR4, NR4R5 or SR4 ; Xl is selected from the group consisting of H, straight chained, branched or cyclic alkyl, CO- alkyl, CO-aryl, CO-alkoxyalkyl, chloro, bromo, fluoro, iodo, OR NR4NR5 or SR5 ; and R4 and R5 are independently hydrogen, acyl (including lower acyl), or alkyl (including but not limited to methyl, ethyl, propyl and cyclopropyl).
In a sixth principal embodiment, a compound of Formula VI, or a pharmaceutically acceptable salt or prodrug thereof, is provided:
wherein: R', R2 and R3 are independently H, phosphate (including mono-, di-or triphosphate and a stabilized phosphate); straight chained, branched or cyclic alkyl (including lower alkyl) ; acyl (including lower acyl) ; CO-alkyl, CO-aryl, CO-alkoxyalkyl, CO-aryloxyalkyl, CO- substituted aryl, sulfonate ester including alkyl or arylalkyl sulfonyl including methanesulfonyl and benzyl, wherein the phenyl group is optionally substituted with one or more substituents as described in the definition of aryl given herein; alkylsulfonyl, arylsulfonyl, aralkylsulfonyl, a lipid, including a phospholipid; an amino acid; and amino acid residue, a carbohydrate; a peptide; cholesterol; or other pharmaceutically acceptable leaving group which when administered in vivo is capable of providing a compound wherein Rl, R2 and/or R3 is independently H or phosphate; wherein at least one of R2 and R3 is not hydrogen; Y is hydrogen, bromo, chloro, fluoro, iodo, OR4, NR4R5 or SR4 ; Xi vis selected from the group consisting of H, straight chained, branched or cyclic alkyl, CO- alkyl, CO-aryl, CO-alkoxyalkyl, chloro, bromo, fluoro, iodo, OR4, NR4NR5 or SR5 ; and R4 and R5 are independently hydrogen, acyl (including lower acyl), or alkyl (including but not limited to methyl, ethyl, propyl and cyclopropyl).
In a seventh principal embodiment, a compound selected from Formulas VII and VIII, or a pharmaceutically acceptable salt or prodrug thereof, is provided: Base Base R' (X R'CL RIO RIO X I Rs Rs OR'OR'OR 2 (VII) (VIII)
wherein: Base is a purine or pyrimidine base as defined herein; R', R2 and R3 are independently H, phosphate (including mono-, di-or triphosphate and a stabilized phosphate); straight chained, branched or cyclic alkyl (including lower alkyl) ; acyl (including lower acyl) ; CO-alkyl, CO-aryl, CO-alkoxyalkyl, CO-aryloxyalkyl, CO- substituted aryl, sulfonate ester including alkyl or arylalkyl sulfonyl including methanesulfonyl and benzyl, wherein the phenyl group is optionally substituted with one or more substituents as described in the definition of aryl given herein; alkylsulfonyl, arylsulfonyl, aralkylsulfonyl, a lipid, including a phospholipid ; an amino acid; and amino acid residue, a carbohydrate; a peptide; cholesterol ; or other pharmaceutically acceptable leaving group which when administered in vivo is capable of providing a compound wherein R', R2 and/or R3 is independently H or phosphate; wherein R2 is not hydrogen; R6 is alkyl (including lower alkyl and halogenated alkyl), CH3, CF3, azido, cyano, alkenyl, <BR> <BR> <BR> <BR> alkynyl, Br-vinyl, 2-Br-ethyl,-C (O) O (alkyl),-C (O) O (lower alkyl),-O (acyl),-O (lower acyl), -O (alkyl),-O (lower alkyl),-O (alkenyl), CF3, chloro, bromo, fluoro, iodo, NO2, NH2, - NH (lower alkyl),-NH (acyl),-N (lower alkyl) 2, -N (acyl) 2; and X is O, S, SO2 or CH2.
In a eighth principal embodiment, a compound of Formulas IX and X, or a pharmaceutically acceptable salt or prodrug thereof, is provided: Rlo Base RIO Base R6 Ru _4 rR7 OR2 OR3 R2 7 OR OR OR R (IX) (X)
wherein: Base is a purine or pyrimidine base as defined herein; R', R2 and R3 are independently H, phosphate (including mono-, di-or triphosphate and a stabilized phosphate); straight chained, branched or cyclic alkyl (including lower alkyl) ; acyl (including lower acyl) ; CO-alkyl, CO-aryl, CO-alkoxyalkyl, CO-aryloxyalkyl, CO- substituted aryl, sulfonate ester including alkyl or arylalkyl sulfonyl including methanesulfonyl and benzyl, wherein the phenyl group is optionally substituted with one or more substituents as described in the definition of aryl given herein; alkylsulfonyl, arylsulfonyl, aralkylsulfonyl, a lipid, including a phospholipid; an amino acid; and amino acid residue, a carbohydrate; a peptide; cholesterol; or other pharmaceutically acceptable leaving group which when administered in vivo is capable of providing a compound wherein Rl, W and/or R3 is independently H or phosphate; wherein R2 is not hydrogen; R6 is alkyl (including lower alkyl and halogenated alkyl), CH3, CF3, azido, cyano, alkenyl, <BR> <BR> <BR> alkynyl, Br-vinyl, 2-Br-ethyl,-C (O) O (alkyl), -C (O) O (lower alkyl),-O (acyl),-O (lower acyl), -O (alkyl),-O (lower alkyl),-O (alkenyl), CF3, chloro, bromo, fluoro, iodo, N02, NH2,- NH (lower alkyl),-NH (acyl), -N (lower alkyl) 2, -N (acyl) 2 ; and R7 is hydrogen, OR3, hydroxy, alkyl (including lower alkyl), azido, cyano, alkenyl, alkynyl, <BR> <BR> <BR> Br-vinyl, -C (O) O (alkyl), -C (O) O (lower alkyl),-O (acyl),-O (lower acyl),-O (alkyl),-O (lower alkyl),-O (alkenyl), chlorine, bromine, iodine, NO2, NH2, -NH (lower alkyl),-NH (acyl), - N (lower alkyl) 2,-N (acyl) 2; and X is O, S, SO2 or CH2.
In a ninth principal embodiment a compound selected from Formulas XI and XII, or a pharmaceutically acceptable salt or prodrug thereof, is provided: RIO Base R O Base R6 R6 X oR2 OR ORZ (XI) (XII)
wherein: Base is a purine or pyrimidine base as defined herein; R', R2 and R3 are independently H, phosphate (including mono-, di-or triphosphate and a stabilized phosphate); straight chained, branched or cyclic alkyl (including lower alkyl) ; acyl (including lower acyl) ; CO-alkyl, CO-aryl, CO-alkoxyalkyl, CO-aryloxyalkyl, CO- substituted aryl, sulfonate ester including alkyl or arylalkyl sulfonyl including methanesulfonyl and benzyl, wherein the phenyl group is optionally substituted with one or more substituents as described in the definition of aryl given herein; alkylsulfonyl, arylsulfonyl, aralkylsulfonyl, a lipid, including a phospholipid ; an amino acid; and amino acid residue, a carbohydrate; a peptide; cholesterol ; or other pharmaceutically acceptable leaving group which when administered in vivo is capable of providing a compound wherein R', W and/or R3 is independently H or phosphate; wherein R2 is not hydrogen; R6 is alkyl (including lower alkyl and halogenated alkyl), CH3, CF3, azido, cyano, alkenyl, <BR> <BR> <BR> <BR> alkynyl, Br-vinyl, 2-Br-ethyl,-C (O) O (alkyl),-C (O) O (lower alkyl),-O (acyl),-O (lower acyl), -O (alkyl),-O (lower alkyl),-O (alkenyl), CF3, chloro, bromo, fluoro, iodo, NO2, NH2,- NH (lower alkyl),-NH (acyl),-N (lower alkyl) 2,-N (acyl) 2 ; and XisO, S, S02 or CH2.
In a tenth principal embodiment the invention provides a compound of Formula XIII, or a pharmaceutically acceptable salt or prodrug thereof : Rl O Base R10 R8 R9 R7 rus R9 (XIII)
wherein: Base is a purine or pyrimidine base as defined herein; Rl is H, phosphate (including mono-, di-or triphosphate and a stabilized phosphate); straight chained, branched or cyclic alkyl (including lower alkyl) ; acyl (including lower acyl) ; CO- alkyl, CO-aryl, CO-alkoxyalkyl, CO-aryloxyalkyl, CO-substituted aryl, sulfonate ester including alkyl or arylalkyl sulfonyl including methanesulfonyl and benzyl, wherein the phenyl group is optionally substituted with one or more substituents as described in the definition of aryl given herein; alkylsulfonyl, arylsulfonyl, aralkylsulfonyl, a lipid, including a phospholipid ; an amino acid; and amino acid residue, a carbohydrate; a peptide; cholesterol ; or other pharmaceutically acceptable leaving group which when administered in vivo is capable of providing a compound wherein R'is H or phosphate; R6 is alkyl (including lower alkyl and halogenated alkyl), CH3, CF3, azido, cyano, alkenyl, alkynyl, Br-vinyl, 2-Br-ethyl,-C (O) O (alkyl),-C (O) O (lower alkyl),-O (acyl),-O (lower acyl), -O (alkyl),-O (lower alkyl),-O (alkenyl), CF3, chloro, bromo, fluoro, iodo, NO2, NH2,- NH (lower alkyl),-NH (acyl),-N (lower alkyl) 2, -N (acyl) 2; R7 and R9 are independently hydrogen, OR2, hydroxy, alkyl (including lower alkyl), azido, cyano, alkenyl, alkynyl, Br-vinyl,-C (O) O (alkyl),-C (O) O (lower alkyl),-O (acyl),-O (lower acyl),-O (alkyl),-O (lower alkyl),-O (alkenyl), chlorine, bromine, iodine, NO2, NH2, -NH (lower alkyl),-NH (acyl),-N (lower alkyl) 2, -N (acyl) 2; wherein at least one of R and R9 is OR, wherein the R is independently phosphate (including mono-, di-or triphosphate and a stabilized phosphate); straight chained, branched or cyclic alkyl (including lower alkyl) ; acyl (including lower acyl) ; CO-alkyl, CO-aryl, CO- alkoxyalkyl, CO-aryloxyalkyl, CO-substituted aryl, sulfonate ester including alkyl or
arylalkyl sulfonyl including methanesulfonyl and benzyl, wherein the phenyl group is optionally substituted with one or more substituents as described in the definition of aryl given herein; alkylsulfonyl, arylsulfonyl, aralkylsulfonyl, a lipid, including a phospholipid ; an amino acid; and amino acid residue, a carbohydrate; a peptide; cholesterol ; or other pharmaceutically acceptable leaving group which when administered in vivo is capable of providing a compound wherein W is H or phosphate; R8 and Rl° are independently H, alkyl (including lower alkyl), chlorine, bromine or iodine; alternatively, R7 and Rl°, R8 and R9, or R8 and Rl° can come together to form a pi bond; and X is O, S, SO2 or CH2.
In a eleventh principal embodiment the invention provides a compound of Formula XIV, or a pharmaceutically acceptable salt or prodrug thereof : Base RIO BaSe X Y R H R7 (XIV) wherein: Base is a purine or pyrimidine base as defined herein; R'is H, phosphate (including mono-, di-or triphosphate and a stabilized phosphate); straight chained, branched or cyclic alkyl (including lower alkyl) ; acyl (including lower acyl) ; CO- alkyl, CO-aryl, CO-alkoxyalkyl, CO-aryloxyalkyl, CO-substituted aryl, sulfonate ester including alkyl or arylalkyl sulfonyl including methanesulfonyl and benzyl, wherein the phenyl group is optionally substituted with one or more substituents as described in the definition of aryl given herein; alkylsulfonyl, arylsulfonyl, aralkylsulfonyl, a lipid, including a phospholipid ; an amino acid; and amino acid residue, a carbohydrate; a peptide; cholesterol ; or other pharmaceutically acceptable leaving group which when administered in vivo is capable of providing a compound wherein R'is H or phosphate; R6 is alkyl (including lower alkyl and halogenated alkyl), CH3, CF3, azido, cyano, alkenyl, <BR> <BR> alkynyl, Br-vinyl, 2-Br-ethyl,-C (O) O (alkyl),-C (O) O (lower alkyl),-O (acyl),-O (lower acyl),
-O (alkyl),-O (lower alkyl),-O (alkenyl), CF3, chloro, bromo, fluoro, iodo, NO2, NH2, - NH (lower alkyl),-NH (acyl),-N (lower alkyl) 2,-N (acyl) 2 ; R and R9 are independently hydrogen, OR2, hydroxy, alkyl (including lower alkyl), azido, cyano, alkenyl, alkynyl, Br-vinyl,-C (O) O (alkyl),-C (O) O (lower alkyl),-O (acyl),-O (lower acyl),-O (alkyl),-O (lower alkyl),-O (alkenyl), chlorine, bromine, iodine, NO2, NH2, -NH (lower alkyl),-NH (acyl),-N (lower alkyl) 2, -N (acyl) 2; wherein at least one of R7 and R9 is OR2, wherein the R2 is independently phosphate (including mono-, di-or triphosphate and a stabilized phosphate); straight chained, branched or cyclic alkyl (including lower alkyl) ; acyl (including lower acyl) ; CO-alkyl, CO-aryl, CO- alkoxyalkyl, CO-aryloxyalkyl, CO-substituted aryl, sulfonate ester including alkyl or arylalkyl sulfonyl including methanesulfonyl and benzyl, wherein the phenyl group is optionally substituted with one or more substituents as described in the definition of aryl given herein; alkylsulfonyl, arylsulfonyl, aralkylsulfonyl, a lipid, including a phospholipid ; an amino acid; and amino acid residue, a carbohydrate; a peptide; cholesterol; or other pharmaceutically acceptable leaving group which when administered in vivo is capable of providing a compound wherein R2 is H or phosphate; Rl° is H, alkyl (including lower alkyl), chlorine, bromine or iodine; alternatively, or R7 and Rl° can come together to form a pi bond; and X is O, S, SO2 or CH2.
In a twelfth principal embodiment, the invention provides a compound of Formula XV, or a pharmaceutically acceptable salt or prodrug thereof : R'O Base R6 R8 R v R7 !.'i' (XV) wherein: Base is a purine or pyrimidine base as defined herein; R'is H, phosphate (including mono-, di-or triphosphate and a stabilized phosphate); straight chained, branched or cyclic alkyl (including lower alkyl) ; acyl (including lower acyl) ; CO-
alkyl, CO-aryl, CO-alkoxyalkyl, CO-aryloxyalkyl, CO-substituted aryl, sulfonate ester including alkyl or arylalkyl sulfonyl including methanesulfonyl and benzyl, wherein the phenyl group is optionally substituted with one or more substituents as described in the definition of aryl given herein; alkylsulfonyl, arylsulfonyl, aralkylsulfonyl, a lipid, including a phospholipid ; an amino acid; and amino acid residue, a carbohydrate; a peptide; cholesterol; or other pharmaceutically acceptable leaving group which when administered in vivo is capable of providing a compound wherein R'is H or phosphate; R6 is alkyl (including lower alkyl and halogenated alkyl), CH3, CF3, azido, cyano, alkenyl, alkynyl, Br-vinyl, 2-Br-ethyl,-C (O) O (alkyl),-C (O) O (lower alkyl),-O (acyl),-O (lower acyl), -O(alkyl), -O(lower alkyl), -O(alkenyl), CF3, chloro, bromo, fluoro, iodo, NO2, NH2, - NH (lower alkyl),-NH (acyl),-N (lower alkyl) 2,-N (acyl) 2; R and R9 are independently hydrogen, OR2, hydroxy, alkyl (including lower alkyl), azido, cyano, alkenyl, alkynyl, Br-vinyl,-C (O) O (alkyl),-C (O) O (lower alkyl),-O (acyl),-O (lower acyl),-O (alkyl),-O (lower alkyl),-O (alkenyl), chlorine, bromine, iodine, N02, NH2, -NH (lower alkyl),-NH (acyl),-N (lower alkyl) 2, -N (acyl) 2 ; wherein at least one of R and R9 is OR2, wherein each R2 is independently phosphate (including mono-, di-or triphosphate and a stabilized phosphate); straight chained, branched or cyclic alkyl (including lower alkyl) ; acyl (including lower acyl) ; CO-alkyl, CO-aryl, CO- alkoxyalkyl, CO-aryloxyalkyl, CO-substituted aryl, sulfonate ester including alkyl or arylalkyl sulfonyl including methanesulfonyl and benzyl, wherein the phenyl group is optionally substituted with one or more substituents as described in the definition of aryl given herein; alkylsulfonyl, arylsulfonyl, aralkylsulfonyl, a lipid, including a phospholipid ; an amino acid; and amino acid residue, a carbohydrate; a peptide; cholesterol; or other pharmaceutically acceptable leaving group which when administered in vivo is capable of providing a compound wherein R2 is H or phosphate; R is H, alkyl (including lower alkyl), chlorine, bromine or iodine; alternatively, R8 and R9 can come together to form a pi bond; X is O, S, SO2 or CH2.
In a thirteenth principal embodiment, a compound of Formula XVI, or a pharmaceutically acceptable salt or prodrug thereof, is provided:
wherein: R', R2 and R3 are independently H, phosphate (including mono-, di-or triphosphate and a stabilized phosphate); straight chained, branched or cyclic alkyl (including lower alkyl) ; acyl (including lower acyl) ; CO-alkyl, CO-aryl, CO-alkoxyalkyl, CO-aryloxyalkyl, CO- substituted aryl, sulfonate ester including alkyl or arylalkyl sulfonyl including methanesulfonyl and benzyl, wherein the phenyl group is optionally substituted with one or more substituents as described in the definition of aryl given herein; alkylsulfonyl, arylsulfonyl, aralkylsulfonyl, a lipid, including a phospholipid ; an amino acid; and amino acid residue, a carbohydrate; a peptide; cholesterol; or other pharmaceutically acceptable leaving group which when administered in vivo is capable of providing a compound wherein R', R2 and/or R3 is independently H or phosphate; wherein at least one of R2 and R3 is not hydrogen; Y is hydrogen, bromo, chloro, fluoro, iodo, OH, OR4, NH, NHR5, NR4R5, SH and SR4 ; Xl and x2 are independently selected from the group consisting of H, straight chained, branched or cyclic alkyl, CO-alkyl, CO-aryl, CO-alkoxyalkyl, chloro, bromo, fluoro, iodo, OH, OR4, NH, NHR5, NR4R5, SH and SR4 ; and R4 and R are independently hydrogen, acyl (including lower acyl), or alkyl (including but not limited to methyl, ethyl, propyl and cyclopropyl).
In a fourteenth principal embodiment, a compound of Formula XVII, or a pharmaceutically acceptable salt or prodrug thereof, is provided:
wherein: R', R2 and R3 are independently H, phosphate (including mono-, di-or triphosphate and a stabilized phosphate); straight chained, branched or cyclic alkyl (including lower alkyl) ; acyl (including lower acyl) ; CO-alkyl, CO-aryl, CO-alkoxyalkyl, CO-aryloxyalkyl, CO- substituted aryl, sulfonate ester including alkyl or arylalkyl sulfonyl including methanesulfonyl and benzyl, wherein the phenyl group is optionally substituted with one or more substituents as described in the definition of aryl given herein; alkylsulfonyl, arylsulfonyl, aralkylsulfonyl, a lipid, including a phospholipid; an amino acid; and amino acid residue, a carbohydrate; a peptide; cholesterol ; or other pharmaceutically acceptable leaving group which when administered in vivo is capable of providing a compound wherein R', R2 and/or R3 is independently H or phosphate; wherein at least one of R2 and R3 is not hydrogen; Y is hydrogen, bromo, chloro, fluoro, iodo, OR4, NR4Rs or SR4 ; Xl is selected from the group consisting of H, straight chained, branched or cyclic alkyl, CO- alkyl, CO-aryl, CO-alkoxyalkyl, chloro, bromo, fluoro, iodo, OR4, NR4NR5 or SRs ; and R4 and R 5 are independently hydrogen, acyl (including lower acyl), or alkyl (including but not limited to methyl, ethyl, propyl and cyclopropyl).
In a fifteenth principal embodiment, a compound selected from Formulas XVIII and XIX, or a pharmaceutically acceptable salt or prodrug thereof, is provided: Base Base RIO >4 Rl° kLJ oR2 RIO X X fizz OR OR OR (XVIII) (XIX)
wherein: Base is a purine or pyrimidine base as defined herein; R', R2 and R3 are independently H, phosphate (including mono-, di-or triphosphate and a stabilized phosphate); straight chained, branched or cyclic alkyl (including lower alkyl) ; acyl (including lower acyl) ; CO-alkyl, CO-aryl, CO-alkoxyalkyl, CO-aryloxyalkyl, CO- substituted aryl, sulfonate ester including alkyl or arylalkyl sulfonyl including methanesulfonyl and benzyl, wherein the phenyl group is optionally substituted with one or more substituents as described in the definition of aryl given herein; alkylsulfonyl, arylsulfonyl, aralkylsulfonyl, a lipid, including a phospholipid ; an amino acid; and amino acid residue, a carbohydrate; a peptide; cholesterol; or other pharmaceutically acceptable leaving group which when administered in vivo is capable of providing a compound wherein Rl, R2 and/or R3 is independently H or phosphate; wherein R2 is not hydrogen; R6 is alkyl (including lower alkyl and halogenated alkyl), CH3, CF3, azido, cyano, alkenyl, <BR> <BR> <BR> <BR> alkynyl, Br-vinyl, 2-Br-ethyl,-C (O) O (alkyl),-C (O) O (lower alkyl),-O (acyl),-O (lower acyl), -O (alkyl),-O (lower alkyl),-O (alkenyl), CF3, chloro, bromo, fluoro, iodo, NO2, NH2,- NH (lower alkyl),-NH (acyl),-N (lower alkyl) 2, -N (acyl) 2 ; and X is O, S, SO2 or CH2.
In a sixteenth principal embodiment the invention provides a compound of Formula XX, or a pharmaceutically acceptable salt or prodrug thereof : R'O Base \ Rl° R8 slob R I 661 R9 R7 (XX)
wherein: Base is a purine or pyrimidine base as defined herein; R'is H, phosphate (including mono-, di-or triphosphate and a stabilized phosphate); straight chained, branched or cyclic alkyl (including lower alkyl) ; acyl (including lower acyl) ; CO- alkyl, CO-aryl, CO-alkoxyalkyl, CO-aryloxyalkyl, CO-substituted aryl, sulfonate ester including alkyl or arylalkyl sulfonyl including methanesulfonyl and benzyl, wherein the phenyl group is optionally substituted with one or more substituents as described in the definition of aryl given herein; alkylsulfonyl, arylsulfonyl, aralkylsulfonyl, a lipid, including a phospholipid ; an amino acid; and amino acid residue, a carbohydrate; a peptide; cholesterol; or other pharmaceutically acceptable leaving group which when administered in vivo is capable of providing a compound wherein Rl is H or phosphate; R6 is alkyl (including lower alkyl and halogenated alkyl), CH3, CF3, azido, cyano, alkenyl, alkynyl, Br-vinyl, 2-Br-ethyl,-C (O) O (alkyl),-C (O) O (lower alkyl),-O (acyl),-O (lower acyl), -O (alkyl),-O (lower alkyl),-O (alkenyl), CF3, chloro, bromo, fluoro, iodo, NO2, NH2, - NH (lower alkyl),-NH (acyl),-N (lower alkyl) 2, -N (acyl) 2; R and R9 are independently hydrogen, OR2, hydroxy, alkyl (including lower alkyl), azido, cyano, alkenyl, alkynyl, Br-vinyl,-C (O) O (alkyl),-C (O) O (lower alkyl),-O (acyl),-O (lower acyl),-O (alkyl),-O (lower alkyl),-O (alkenyl), chlorine, bromine, iodine, NO2, NH2, -NH (lower alkyl),-NH (acyl),-N (lower alkyl) 2,-N (acyl) 2; wherein at least one of R7 and R9 is OR2, wherein each R2 is independently phosphate (including mono-, di-or triphosphate and a stabilized phosphate); straight chained, branched or cyclic alkyl (including lower alkyl) ; acyl (including lower acyl) ; CO-alkyl, CO-aryl, CO- alkoxyalkyl, CO-aryloxyalkyl, CO-substituted aryl, sulfonate ester including alkyl or
arylalkyl sulfonyl including methanesulfonyl and benzyl, wherein the phenyl group is optionally substituted with one or more substituents as described in the definition of aryl given herein; alkylsulfonyl, arylsulfonyl, aralkylsulfonyl, a lipid, including a phospholipid ; an amino acid; and amino acid residue, a carbohydrate; a peptide; cholesterol ; or other pharmaceutically acceptable leaving group which when administered in vivo is capable of providing a compound wherein W is H or phosphate; R and R10 are independently H, alkyl (including lower alkyl), chlorine, bromine or iodine; alternatively, R7 and Rl°, R8 and R9, or R and Rl° can come together to form a pi bond; and X is O, S, SO2 or CH2.
In one embodiment, the amino acid residue is of the formula C (O) C (R") (R) (NR R), wherein Rl'is the side chain of an amino acid and wherein, as in proline, R"can optionally be attached to Rl3 to form a ring structure; or alternatively, R"is an alkyl, aryl, heteroaryl or heterocyclic moiety; R12 is hydrogen, alkyl (including lower alkyl) or aryl ; and R'3 and R'4 are independently hydrogen, acyl (including an acyl derivative attached to R") or alkyl (including but not limited to methyl, ethyl, propyl, and cyclopropyl).
In another preferred embodiment, at least one of R2 and R3 is an amino acid residue, and is preferably L-valinyl.
The (3-D-and ß-L-nucleosides of this invention may inhibit HCV polymerase activity.
Nucleosides can be screened for their ability to inhibit HCV polymerase activity in vitro according to screening methods set forth more particularly herein. One can readily determine the spectrum of activity by evaluating the compound in the assays described herein or with another confirmatory assay.
In one embodiment the efficacy of the anti-HCV compound is measured according to the concentration of compound necessary to reduce the plaque number of the virus in vitro, according to methods set forth more particularly herein, by 50% (i. e. the compound's ECso).
In preferred embodiments the parent of the prodrug compound exhibits an EC50 of less than
25,15, 10,5, or I micromolar. In one embodiment the efficacy of the anti-Flaviviridae compound is measured according to the concentration of compound necessary to reduce the plaque number of the virus in vitro, according to methods set forth more particularly herein, by 50% (i. e. the compound's ECso). In preferred embodiments the compound exhibits an EC50 of less than 15 or 10 micromolar, when measured according to the polymerase assay described in Ferrari et al., J. Virol., 73: 1649-1654,1999 ; Ishii et al., Hepatology, 29: 1227- 1235,1999 ; Lohmann et al., J. Biol. Chem., 274: 10807-10815,1999 ; or Yamashita et al, J.
Biol. Chem., 273: 15479-15486,1998.
In another embodiment, combination and/or alternation therapy are provided. In combination therapy, an effective dosage of two or more agents are administered together, whereas during alternation therapy an effective dosage of each agent is administered serially.
The dosages will depend on absorption, inactivation, and excretion rates of the drug as well as other factors known to those of skill in the art. It is to be noted that dosage values will also vary with the severity of the condition to be alleviated. It is to be further understood that for any particular subject, specific dosage regimens and schedules should be adjusted over time according to the individual need and the professional judgment of the person administering or supervising the administration of the compositions.
The invention also provides combinations of at least two of the herein described prodrugs. The invention further provides at least one of the described 2'and 3'-prodrugs in combination or alternation with a second nucleoside that exhibits activity against a Flaviviridae virus, including but not limited to a parent drug of any of the prodrugs defined herein, i. e. ß-D-2'-methyl-cytidine, P-D-2'-methyl-thymidine, 3-D-2'-methyl-adenosine, (3- D-2'-methyl-guanosine, (3-D-2'-methyl-5-fluorocytidine and/or P-D-2'-methyl-uridine.
Alternatively, the 2'or 3'-prodrugs can be administered in combination or alternation with other anti-Flaviviridae agent exhibits an EC50 of less than 10 or 15 micromolar, or their prodrugs or pharmaceutically acceptable salts.
Nonlimiting examples of antiviral agents that can be used in combination with the compounds disclosed herein include: (1) an interferon and/or ribavirin; (2) Substrate-based NS3 protease inhibitors;. (3) Non-substrate-based inhibitors; (4) Thiazolidine derivatives ; (5) Thiazolidines and benzanilides ; (6) A phenan-threnequinone; (7) NS3 inhibitors; (8) HCV helicase inhibitors; (9) polymerase inhibitors, including RNA-dependent RNA-polymerase inhibitors; (10)
Antisense oligodeoxynucleotides (11) Inhibitors of IRES-dependent translation; (12) Nuclease-resistant ribozymes ; and (13) other compounds that exhibit activity against a flaviviridae. The invention further includes administering the prodrug in combination or alternation with an immune modulator or other pharmaceutically active modifer of viral replication, including a biological material such as a protein, peptide, oligonucleotide, or gamma globulin, including but not limited to interfereon, interleukin, or an antisense oligonucleotides to genes which express or regulate Flaviviridae replication.
The compounds described herein have a number of enantiomeric configurations, any of which can be used as desired. The parent nucleoside framework can exist as a P-D or P-L nucleoside. In a preferred embodiment, the compound is administered in a form that is at least 90% of the ß-D enantiomer. In another embodiment, the compound is at least 95% of the P-D enantiomer. Certain prodrug acyl esters, specifically including amino acid esters, also have enantiomeric forms. In alternative embodiments, the compounds are used as racemic mixtures or as any combination of P-D or P-L parent nucleoside and L or D amino acid.
In an alternative embodiment, the parent nucleoside compounds of any of the 2'or 3'- prodrugs (i. e. , the nucleosides without the 2'or 3'cleavable moieties) provided for the treatment of a Flaviviridae, and in particular, an HCV infection.
BRIEF DESCRIPTION OF THE FIGURES Figure 1 provides the structure of various non-limiting examples of nucleosides of the present invention, as well as other known nucleosides, in particular FIAU and ribavirin.
Figure 2 provides a non-limiting example of the steps involved in esterification of the 1', 2', 3'or 4'-branched 3-D or ß-L nucleoside to obtain a 2'-prodrug. The same general procedure can be used to obtain the 3'-prodrug by selectively protecting the 2'and 5'- hydroxyl groups or protecting the 2', 3'and 5'-hydroxyl groups and selectively deprotecting the 3'-hydroxyl.
Figure 3 provides a non-limiting example of the steps involved in esterification of the 1', 2', 3'or 4'-branched R-D or ß-L nucleoside to obtain a 3'-prodrug.
Figure 4 provides a non-limiting example of the esterification of the 1', 2', 3'or 4'- branched ß-D or ß-L nucleoside to obtain a 2', 3'-prodrug.
Figure 5 is an illustration of a process of synthesizing a ß-D-2'-C-methyl- ribofuransyl-cytidine or a 3'-O-L-valine ester thereof.
Figure 6 is an illustration of another process of synthesizing a ß-D-2'-C-methyl- ribofuransyl-cytidine or a 3'-O-L-valine ester thereof.
Figure 7 is a diagram of a process of synthesizing a ß-D-2'-C-methyl-2'-acetyl- ribofuransyl-cytidine-3'-O-L-valine ester.
Figure 8 is a diagram of a process of synthesizing a ß-D-2'-C-methyl-2'-acetyl- ribofuransyl-cytidine-3'-O-L-proline ester.
Figure 9 is a diagram of a process of synthesizing a ß-D-2'-C-methyl-2'-acetyl- ribofuransyl-cytidine-3'-O-L-alanine ester.
Figure 10 is a diagram of a process of synthesizing a ß-D-2'-C-methyl-2'- (cyclohexane carboxylate)-ribofuransyl-cytidine-3'-O-L-valine ester.
Figure 11 is a graph showing the concentration of BVDB (Loglo units/ml) over a concentration range of four test compounds and ribavirin as a control in a cell based assay using de novo BVDV infected MDBK cells. This graph shows the antiviral potency of these compounds.
Figure 12 is a photocopy of a gel illustrating the site-specific chain termination of in vitro RNA synthesis by ß-D-2'-C-methyl-ribofuranosyl cytidine triphosphate at specified guanine residues in RNA templates, as described in Example 32.
Figure 13 is a graph of the the titer of bovine viral diarrhea virus (BVDV) over number of passages of BVDV infected MDBK cells, indicating eradication of a persistent BVDV infection by prolonged treatment with ß-D-2'-C-methyl-ribofuranosyl cytidine (16uM) as described in Example 33. Arrows indicate points at which a portion of cells were withdrawn from drug treatment.
Figure 14a and 14b are graphs of the concentration of bovine viral diarrhea virus (BVDV) in MDBK cells persistently infected with the virus, as described in Example 34.
These graphs indicate the synergy between P-D-2'-C-methyl-ribofuranosyl cytidine and interferon alpha 2b (IntronA) in reducing the viral titer. Figure 14a is a graph of the effect of P-D-2'-C-methyl-ribofuranosyl cytidine and IntronA on BVDV (strain NY-1) titers in
persistently infected MDBK cells over time. Figure 14b is a graph of the effect of ß-D-2'-C- methyl-ribofuranosyl cytidine in combination with IntronA on BVDV (strain I-N-dIns) titers in persistently-infected MDBK cells.
Figure 15a-d illustrate the results of experiments studying the development of resistance to ß-D-2'-C-methyl-ribofuranosyl cytidine treated MDBK cells, infected with bovine viral diarrhea virus (BVDV), as described in Example 35. Figure 15a is a graph of a representative experiment showing the effect over twenty eight days of ß-D-2'-C-methyl- ribofuranosyl cytidine or IntronA treatment on BVDV (strain I-N-dIns) titers in persistently infected MDBK cells. Figure 15b is a photocopy of a dish plated with infected MDBK cells that illustrates the size of the foci formed by phenotypes of the wild-type BVDV (strain I-N- dIns), versus the P-D-2'-C-methyl-ribofuranosyl cytidine-resistant BVDV (I-N-dIns 107R), indicating that the resistant virus formed much smaller foci than the wild-type, I-N-dIns strain. Figure 15c is a graph of the titer of BVDV strains I-N-dlns or I-N-dIns-107R over hours post-infection in infected MDBK cells. Figure 15d is a graph of the effect of Intron A on the BVDV viral titer yield in de novo-infected MDBK cells treated with IntronA.
Figure 16 is a graph of the concentration of hepatitis C virus (Logio) in individual chimpanzees over days of treatment with P-D-2'-C-methyl-ribofuranosyl cytidine-3'-O-L- valine ester as described in Example 36.
Figure 17 is a graph of the concentration of hepatitis C virus in individual chimpanzees over days of treatment with ß-D-2'-C-methyl-ribofuranosyl cytidine-3'-O-L- valine ester as compared to baseline, as described in Example 36.
Figure 18 is a graph of percent of total ß-D-2'-C-methyl-ribofuranosyl cytidine-3'-O- L-valine ester remaining in samples over time after incubation of the drug in human plasma at 4°C, 21°C, and 37°C, as described in Example 37.
Figure 19a is a graph showing the relative levels of the di-and tri-phosphate derivatives of ß-D-2'-C-methyl-ribofuranosyl cytidine and P-D-2'-C-methyl-ribofuranosyl uridine (mUrd) after incubation of HepG2 cells with 10 uM P-D-2'-C-methyl-ribofuranosyl cytidine over time, as described in Example 37. Figure 19b is a graph of the decay of the tri- phosphate derivative of ß-D-2'-C-methyl-ribofuranosyl cytidine after incubation of HepG2 cells with 10 pM ß-D-2'-C-methyl-ribofuranosyl cytidine over time. Figure 19c is a graph of the concentration of the di-and tri-phosphate derivatives of P-D-2'-C-methyl-ribofuranosyl cytidine and P-D-2'-C-methyl-ribofuranosyl uridine (mUrd) after incubation of HepG2 cells
with 10pM ß-D-2'-C-methyl-ribofuranosyl cytidine at increasing concentrations of the drug (UM)- Figure 20 is a graph of the concentration (ng/ml) of ß-D-2'-C-methyl-ribofuranosyl cytidine in human serum after administration of ß-D-2'-C-methyl-ribofuranosyl cytidine-3'- O-L-valine ester to patients, as described in Example 40.
Figure 21 is a graph of the median change of the titer of hepatitis C virus in human patients after administration of ß-D-2'-C-methyl-ribofuranosyl cytidine-3'-O-L-valine ester, as described in Example 40. The graph indicates change from baseline in Log) o HCV RNA by patient visit.
Figure 22 is a table of the ECso and CCso of representative compounds in a BVDV cell protection assay.
DETAILED DESCRIPTION OF THE INVENTION The invention as disclosed herein is a compound, a method and composition for the treatment of a Flaviviridae infection in humans and other host animals. The method includes the administration of an effective HCV or Flaviviridae treatment amount of a 2'-or 3'- prodrug of a 1', 2', 3'or 4'-branched ß-D or ß-L nucleoside as described herein or a pharmaceutically acceptable salt, derivative or prodrug thereof, optionally in a pharmaceutically acceptable carrier. The compound of this invention either possesses antiviral (i. e. , anti-HCV) activity, or is metabolized to a compound that exhibits such activity.
The 2'-or 3'-prodrug of a 1', 2', 3'or 4'-branched ß-D or p-L nucleoside are acyl derivates of a secondary or tertiary alcohol alpha to a secondary or tertiary carbon. Due to the steric hindrance of these prodrugs over the 5'-prodrugs, an acyl derivative of a primary alcohol, these prodrugs differently modulate the biological properties of the molecule in vivo.
It has been discovered that the 2'-and 3'-prodrugs of a 1', 2', 3'or 4'-branched ß-D or ß-L nucleoside can provide a drug with increased half-life and improved pharmacokinetic profile.
The 2'-and 3'-prodrugs in a preferred embodiment is a cleavable acyl group, and most particularly, an amino acid moiety, prepared from any naturally occurring or synthetic
a, p y or 8 amino acid, including but is not limited to, glycine, alanine, valine, leucine, isoleucine, methionine, phenylalanine, tryptophan, proline, serine, threonine, cysteine, tyrosine, asparagine, glutamine, aspartate, glutamate, lysine, arginine and histidine. In a preferred embodiment, the amino acid is in the L-configuration. Alternatively, the amino acid can be a derivative of alanyl, valinyl, leucinyl, isoleuccinyl, prolinyl, phenylalaninyl, tryptophanyl, methioninyl, glycinyl, serinyl, threoninyl, cysteinyl, tyrosinyl, asparaginyl, glutaminyl, aspartoyl, glutaroyl, lysinyl, argininyl, histidinyl, (3-alanyl, ß-valinyl, ß-leucinyl, ß-isoleuccinyl, p-prolinyl, p-phenylalaninyl, P-tryptophanyl, ß-methioninyl, ß-glycinyl, P- serinyl, ß-threoninyl, ß-cysteinyl, ß-tyrosinyl, ß-asparaginyl, ß-glutaminyl, ß-aspartoyl, ß- glutaroyl, ß-lysinyl, ß-argininyl or (3-histidinyl. In one particular, embodiment, the moiety is a valine ester. One particularly preferred compound is the 3'-valine ester of 2'-methyl-ribo- cytidine.
The oral bio-availability of 1', 2', 3'or 4'-branched ß-D or ß-L nucleoside as the neutral base and the HCl salt is low in rodents and non-human primates. It has been discovered that there is significant competition of 1', 2', 3'or 4'-branched P-D or R-L nucleoside with other nucleosides or nucleoside analogs for absorption, or transport, from the gastrointestinal tract and competition of other nucleosides or nucleoside analogs for the absorption with 1', 2', 3'or 4'-branched ß-D or ß-L nucleoside. In order to improve oral bioavailability and reduce the potential for drug-drug interaction, 2'and 3'-prodrugs of 1', 2', 3'or 4'-branched R-D or ß-L nucleoside were obtained with higher oral bioavailability than the parent molecule and a reduced effect on the bioavailability of other nucleosides or nucleoside analogs used in combination.
The 2', 3', and/or 5'-mono, di or trivaline ester of a 1', 2', 3'or 4'-branched ß-D or R- L nucleoside have higher oral bioavailability than the parent 1', 2', 3'or 4'-branched ß-D or ß-L nucleoside and reduced interaction with other nucleosides or nucleoside analogs when used in combination as compared to 1', 2', 3'or 4'-branched ß-D or ß-L nucleoside.
The 2', 3', and/or 5'-mono, di or trivaline ester of a 1', 2', 3'or 4'-branched R-D or R- L nucleoside can be converted to the parent 1', 2', 3'or 4'-branched R-D or ß-L nucleoside through de-esterification in the gastrointestinal mucosa, blood or liver. The 2', 3', and/or 5'- mono, di or trivaline ester of a 1', 2', 3'or 4'-branched 3-D or ß-L nucleoside can be actively transported from the gastrointestinal lumen after oral delivery into the bloodstream by an amino acid transporter function in the mucosa of the gastrointestinal tract. This accounts for
the increase in oral bioavailability compared to the parent 1', 2', 3'or 4'-branched (3-D or O-L nucleoside that is transported primarily by a nucleoside transporter function. There is reduced competition for uptake of the 2', 3', and/or 5'-mono, di or trivaline ester of 1', 2', 3' or 4'-branched O-D or O-L nucleoside with other nucleosides or nucleoside analogs that are transported by the nucleoside transporter function and not the amino acid transporter function. As partial de-esterification of the di or trivaline ester of 1', 2', 3'or 4'-branched p- D or ß-L nucleoside occurs prior to complete absorption, the mono or divaline ester continues to be absorbed using the amino acid transporter function. Therefore, the desired outcome of better absorption, or bioavailability, and reduced competition with other nucleosides or nucleoside analogs for uptake into the bloodstream can be maintained.
In summary, the present invention includes the following features: (a) a 2'and/or 3'-prodrug of a 1', 2', 3'or 4'-branched ß-D or R-L nucleoside, as described herein, and pharmaceutically acceptable salts and compositions thereof; (b) a 2'and/or 3'-prodrug of a 1', 2', 3'or 4'-branched ß-D or ß-L nucleoside as described herein, and pharmaceutically acceptable salts and compositions thereof for use in the treatment and/or prophylaxis of a Flaviviridae infection, especially in individuals diagnosed as having a Flaviviridae infection or being at risk of becoming infected by hepatitis C; (c) a 2'and/or 3'-prodrug of a 1', 2', 3'or 4'-branched ß-D or ß-L nucleoside, or their pharmaceutically acceptable salts and compositions as described herein substantially in the absence of the opposite enantiomers of the described nucleoside, or substantially isolated from other chemical entities; (d) processes for the preparation of a 2'and/or 3'-prodrug of a 1', 2', 3'or 4'-branched D or P-L nucleoside, as described in more detail below; (e) pharmaceutical formulations comprising a 2'and/or 3'-prodrug of a 1', 2', 3'or 4'- branched ß-D or ß-L nucleoside or a pharmaceutically acceptable salt thereof together with a pharmaceutically acceptable carrier or diluent; (f) pharmaceutical formulations comprising a 2'and/or 3'-prodrug of a 1', 2', 3'or 4'- branched P-D or P-L nucleoside or a pharmaceutically acceptable salt thereof together with one or more other effective anti-HCV agents, optionally in a pharmaceutically acceptable carrier or diluent;
(g) pharmaceutical formulations comprising a 2'and/or 3'-prodrug of a 1', 2', 3'or 4'- branched ß-D or R-L nucleoside or a pharmaceutically acceptable salt thereof together with the parent of a different a 1', 2', 3'or 4'-branched ß-D or ß-L nucleoside, optionally in a pharmaceutically acceptable carrier or diluent; (h) a method for the treatment and/or prophylaxis of a host infected with Flaviviridae that includes the administration of an effective amount of a 2'and/or 3'-prodrug of a 1', 2', 3'or 4'-branched ß-D or ß-L nucleoside, its pharmaceutically acceptable salt or composition; (i) a method for the treatment and/or prophylaxis of a host infected with Flaviviridae that includes the administration of an effective amount of a 2'and/or 3'-prodrug of a 1', 2', 3'or 4'-branched ß-D or ß-L nucleoside, its pharmaceutically acceptable salt or composition in combination and/or alternation with one or more effective anti-HCV agent; (j) a method for the treatment and/or prophylaxis of a host infected with Flaviviridae that includes the administration of an effective amount of a 2'and/or 3'-prodrug of a 1', 2', 3'or 4'-branched P-D or ß-L nucleoside, or its pharmaceutically acceptable salt or composition with the parent of a different a 1', 2', 3'or 4'-branched ß-D or ß-L nucleoside; (k) a method for the treatment and/or prophylaxis of a host infected with Flaviviridae that includes the administration of an effective amount of a 2'and/or 3'-prodrug of a ß-D- 2'-methyl-cytidine, or its pharmaceutically acceptable salt or composition thereof; (1) a method for the treatment and/or prophylaxis of a host infected with Flaviviridae that includes the administration of an effective amount of the 3', 5'-divalyl or diacetyl ester of R-D-2'-methyl-cytidine, or its pharmaceutically acceptable salt or composition thereof; (m) use of a 2'and/or 3'-prodrug of a 1', 2', 3'or 4'-branched ß-D or R-L nucleoside, and pharmaceutically acceptable salts and compositions thereof for the treatment and/or prophylaxis of a Flaviviridae infection in a host; (n) use of a 2'and/or 3'-prodrug of a 1', 2', 3'or 4'-branched P-D or ß-L nucleoside, its pharmaceutically acceptable salt or composition in combination and/or alternation with one or more effective anti-HCV agent for the treatment and/or prophylaxis of a Flaviviridae infection in a host;
(o) use of a 2'and/or 3'-prodrug of a 1', 2', 3'or 4'-branched ß-D or R-L nucleoside, or its pharmaceutically acceptable salt or composition with the parent of a different a 1', 2', 3'or 4'-branched R-D or ß-L nucleoside for the treatment and/or prophylaxis of a Flaviviridae infection in a host; (p) use of a 2'and/or 3'-prodrug of a ß-D-2'-methyl-cytidine, or its pharmaceutically acceptable salt or composition thereof for the treatment and/or prophylaxis of a Flaviviridae infection in a host; (q) use of the 3', 5'-divalyl or diacetyl ester of ß-D-2'-methyl-cytidine, or its pharmaceutically acceptable salt or composition thereof for the treatment and/or prophylaxis of a Flaviviridae infection in a host; (r) use of a 2'and/or 3'-prodrug of a 1', 2', 3'or 4'-branched ß-D or ß-L nucleoside, and pharmaceutically acceptable salts and compositions thereof in the manufacture of a medicament for treatment and/or prophylaxis of a Flaviviridae infection; (s) use of a 2'and/or 3'-prodrug of a 1', 2', 3'or 4'-branched ß-D or ß-L nucleoside, its pharmaceutically acceptable salt or composition in combination and/or alternation with one or more effective anti-HCV agent in the manufacture of a medicament for the treatment and/or prophylaxis of a Flaviviridae infection in a host; (t) use of a 2'and/or 3'-prodrug of a 1', 2', 3'or 4'-branched ß-D or P-L nucleoside, or its pharmaceutically acceptable salt or composition with the parent of a different a 1', 2', 3'or 4'-branched R-D or ß-L nucleoside in the manufacture of a medicament for the treatment and/or prophylaxis of a Flaviviridae infection in a host; (u) use of a 2'and/or 3'-prodrug of a ß-D-2'-methyl-cytidine, or its pharmaceutically acceptable salt or composition thereof in the manufacture of a medicament for the treatment and/or prophylaxis of a Flaviviridae infection in a host; and (v) use of the 3', 5'-divalyl or diacetyl ester of ß-D-2'-methyl-cytidine, or its pharmaceutically acceptable salt or composition thereof in the manufacture of a medicament for the treatment and/or prophylaxis of a Flaviviridae infection in a host.
Flaviviridae included within the scope of this invention are discussed generally in Fields Virology, Editors: Fields, B. N. , Knipe, D. M. , and Howley, P. M. , Lippincott-Raven Publishers, Philadelphia, PA, Chapter 31,1996. In a particular embodiment of the invention, the Flaviviridae is HCV. In an alternate embodiment of the invention, the Flaviviridae is a
flavivirus or pestivirus. Specific flaviviruses include, without limitation: Absettarov, Alfuy, Apoi, Aroa, Bagaza, Banzi, Bouboui, Bussuquara, Cacipacore, Carey Island, Dakar bat, Dengue 1, Dengue 2, Dengue 3, Dengue 4, Edge Hill, Entebbe bat, Gadgets Gully, Hanzalova, Hypr, Ilheus, Israel turkey meningoencephalitis, Japanese encephalitis, Jugra, Jutiapa, Kadam, Karshi, Kedougou, Kokobera, Koutango, Kumlinge, Kunjin, Kyasanur Forest disease, Langat, Louping ill, Meaban, Modoc, Montana myotis leukoencephalitis, Murray valley encephalitis, Naranjal, Negishi, Ntaya, Omsk hemorrhagic fever, Phnom-Penh bat, Powassan, Rio Bravo, Rocio, Royal Farm, Russian spring-summer encephalitis, Saboya, St. Louis encephalitis, Sal Vieja, San Perlita, Saumarez Reef, Sepik, Sokuluk, Spondweni, Stratford, Tembusu, Tyuleniy, Uganda S, Usutu, Wesselsbron, West Nile, Yaounde, Yellow fever, and Zika.
Pestiviruses included within the scope of this invention are discussed generally in Fields Virology, Editors: Fields, B. N. , Knipe, D. M. , and Howley, P. M. , Lippincott-Raven Publishers, Philadelphia, PA, Chapter 33,1996. Specific pestiviruses include, without limitation: bovine viral diarrhea virus ("BVDV"), classical swine fever virus ("CSFV,"also called hog cholera virus), and border disease virus ("BDV").
I. Active Compounds In a first principal embodiment, a compound of Formula (I), or a pharmaceutically acceptable salt or prodrug thereof, is provided: wherein: R', R2 and R3 are independently H, phosphate (including mono-, di-or triphosphate and a stabilized phosphate); straight chained, branched or cyclic alkyl (including lower alkyl) ; acyl
(including lower acyl) ; CO-alkyl, CO-aryl, CO-alkoxyalkyl, CO-aryloxyalkyl, CO- substituted aryl, sulfonate ester including alkyl or arylalkyl sulfonyl including methanesulfonyl and benzyl, wherein the phenyl group is optionally substituted with one or more substituents as described in the definition of aryl given herein; alkylsulfonyl, arylsulfonyl, aralkylsulfonyl, a lipid, including a phospholipid ; an amino acid; and amino acid residue, a carbohydrate; a peptide; cholesterol; or other pharmaceutically acceptable leaving group which when administered in vivo is capable of providing a compound wherein Rl, R2 and/or R3 is independently H or phosphate; wherein at least one of R2 and R3 is not hydrogen; Y is hydrogen, bromo, chloro, fluoro, iodo, OH, OR4, NH, NHR5, NR4R5, SH and SR4 ; Xl and x2 are independently selected from the group consisting of H, straight chained, branched or cyclic alkyl, CO-alkyl, CO-aryl, CO-alkoxyalkyl, chloro, bromo, fluoro, iodo, OH, OR4, NH, NHR5, NR4R5, SH and SR4 ; and R4 and R5 are independently hydrogen, acyl (including lower acyl), or alkyl (including but not limited to methyl, ethyl, propyl and cyclopropyl).
In a preferred subembodiment, a compound of Formula I, or a pharmaceutically acceptable salt or prodrug thereof, is provided wherein: R'is H or phosphate (preferably H); R and R3 are independently H, phosphate, acyl or an amino acid residue, wherein at least one of R2 and R3 is acyl or an amino acid residue; Xl is H; X2 is H or NH2 ; and Y is hydrogen, bromo, chloro, fluoro, iodo, NH2 or OH.
In a second principal embodiment, a compound of Formula II, or a pharmaceutically acceptable salt or prodrug thereof, is provided:
wherein: R', R2 and R3 are independently H, phosphate (including mono-, di-or triphosphate and a stabilized phosphate); straight chained, branched or cyclic alkyl (including lower alkyl) ; acyl (including lower acyl) ; CO-alkyl, CO-aryl, CO-alkoxyalkyl, CO-aryloxyalkyl, CO- substituted aryl, sulfonate ester including alkyl or arylalkyl sulfonyl including methanesulfonyl and benzyl, wherein the phenyl group is optionally substituted with one or more substituents as described in the definition of aryl given herein; alkylsulfonyl, arylsulfonyl, aralkylsulfonyl, a lipid, including a phospholipid ; an amino acid; and amino acid residue, a carbohydrate; a peptide; cholesterol; or other pharmaceutically acceptable leaving group which when administered in vivo is capable of providing a compound wherein R', R2 and/or R3 is independently H or phosphate; wherein at least one of R2 and R3 is not hydrogen; Y is hydrogen, bromo, chloro, fluoro, iodo, OR4, NR4R5 or SR4 ; Xl and x2 are independently selected from the group consisting of H, straight chained, branched or cyclic alkyl, CO-alkyl, CO-aryl, CO-alkoxyalkyl, chloro, bromo, fluoro, iodo, OR4, NR4NR5 or SR5 ; and R4 and R5 are independently hydrogen, acyl (including lower acyl), or alkyl (including but not limited to methyl, ethyl, propyl and cyclopropyl).
In a preferred subembodiment, a compound of Formula II, or a pharmaceutically acceptable salt or prodrug thereof, is provided wherein: Rl is H or phosphate (preferably H);
R and R3 are independently H, phosphate, acyl or an amino acid residue, wherein at least one of R2 and R3 is acyl or an amino acid residue; X'is H; X2 is H or NH2 ; and Y is hydrogen, bromo, chloro, fluoro, iodo, NHZ or OH.
In a third principal embodiment, a compound of Formula III, or a pharmaceutically acceptable salt or prodrug thereof, is provided: wherein: Rl, R2 and R3 are independently H, phosphate (including mono-, di-or triphosphate and a stabilized phosphate); straight chained, branched or cyclic alkyl (including lower alkyl) ; acyl (including lower acyl) ; CO-alkyl, CO-aryl, CO-alkoxyalkyl, CO-aryloxyalkyl, CO- substituted aryl, sulfonate ester including alkyl or arylalkyl sulfonyl including methanesulfonyl and benzyl, wherein the phenyl group is optionally substituted with one or more substituents as described in the definition of aryl given herein; alkylsulfonyl, arylsulfonyl, aralkylsulfonyl, a lipid, including a phospholipid ; an amino acid; and amino acid residue, a carbohydrate; a peptide; cholesterol ; or other pharmaceutically acceptable leaving group which when administered in vivo is capable of providing a compound wherein R', R2 and/or R 3is independently H or phosphate; wherein at least one of R2 and R 3is not hydrogen; Y is hydrogen, bromo, chloro, fluoro, iodo, OR4, NR4R5 or SR4 ; X1 and X2 are independently selected from the group consisting of H, straight chained, branched or cyclic alkyl, CO-alkyl, CO-aryl, CO-alkoxyalkyl, chloro, bromo, fluoro, iodo, OR4, NR4NR5 or SR5 ; and
R4 and R are independently hydrogen, acyl (including lower acyl), or alkyl (including but not limited to methyl, ethyl, propyl and cyclopropyl).
In a preferred subembodiment, a compound of Formula III, or a pharmaceutically acceptable salt or prodrug thereof, is provided wherein: R'is H or phosphate (preferably H); R2 and R3 are independently H, phosphate, acyl or an amino acid residue, wherein at least one of R2 and R3 is acyl or an amino acid residue; Xl is H; X2 is H or NH2 ; and Y is hydrogen, bromo, chloro, fluoro, iodo, NH2 or OH.
In a fourth principal embodiment, a compound of Formula IV, or a pharmaceutically acceptable salt or prodrug thereof, is provided: wherein: R', R2 and R3 are independently H, phosphate (including mono-, di-or triphosphate and a stabilized phosphate); straight chained, branched or cyclic alkyl (including lower alkyl) ; acyl (including lower acyl) ; CO-alkyl, CO-aryl, CO-alkoxyalkyl, CO-aryloxyalkyl, CO- substituted aryl, sulfonate ester including alkyl or arylalkyl sulfonyl including methanesulfonyl and benzyl, wherein the phenyl group is optionally substituted with one or more substituents as described in the definition of aryl given herein; alkylsulfonyl, arylsulfonyl, aralkylsulfonyl, a lipid, including a phospholipid; an amino acid; and amino acid residue, a carbohydrate; a peptide; cholesterol; or other pharmaceutically acceptable leaving group which when administered in vivo is capable of providing a compound wherein R', R2 and/or R3 is independently H or phosphate;
wherein at least one of R2 and R3 is not hydrogen; Y is hydrogen, bromo, chloro, fluoro, iodo, OR4, NR4 or SR4 ; Xi is selected from the group consisting of H, straight chained, branched or cyclic alkyl, CO- alkyl, CO-aryl, CO-alkoxyalkyl, chloro, bromo, fluoro, iodo, OR4, NR4NR5 or SR5 ; and R4 and R5 are independently hydrogen, acyl (including lower acyl), or alkyl (including but not limited to methyl, ethyl, propyl and cyclopropyl).
In a preferred subembodiment, a compound of Formula IV, or a pharmaceutically acceptable salt or prodrug thereof, is provided wherein: R'is H or phosphate (preferably H); R2 and R3 are independently H, phosphate, acyl or an amino acid residue, wherein at least one of R 2and R 3is acyl or an amino acid residue; Xl is H or CH3; and Y is hydrogen, bromo, chloro, fluoro, iodo, NH2 or OH.
In a fifth principal embodiment, a compound of Formula V, or a pharmaceutically acceptable salt or prodrug thereof, is provided: wherein: R', R2 and R3 are independently H, phosphate (including mono-, di-or triphosphate and a stabilized phosphate); straight chained, branched or cyclic alkyl (including lower alkyl) ; acyl (including lower acyl) ; CO-alkyl, CO-aryl, CO-alkoxyalkyl, CO-aryloxyalkyl, CO- substituted aryl, sulfonate ester including alkyl or arylalkyl sulfonyl including methanesulfonyl and benzyl, wherein the phenyl group is optionally substituted with one or more substituents as described in the definition of aryl given herein; alkylsulfonyl,
arylsulfonyl, aralkylsulfonyl, a lipid, including a phospholipid ; an amino acid; and amino acid residue, a carbohydrate; a peptide; cholesterol; or other pharmaceutically acceptable leaving group which when administered in vivo is capable of providing a compound wherein R', R2 and/or R3 is independently H or phosphate; wherein at least one of R2 and R3 is not hydrogen; Y is hydrogen, bromo, chloro, fluoro, iodo, OR4, NR4R5 or SR4 ; Xl is selected from the group consisting of H, straight chained, branched or cyclic alkyl, CO- alkyl, CO-aryl, CO-alkoxyalkyl, chloro, bromo, fluoro, iodo, oR4, NR4NR5 or SR ; and R4 and R5 are independently hydrogen, acyl (including lower acyl), or alkyl (including but not limited to methyl, ethyl, propyl and cyclopropyl).
In a preferred subembodiment, a compound of Formula V, or a pharmaceutically acceptable salt or prodrug thereof, is provided wherein: R'is H or phosphate (preferably H); R2 and R3 are independently H, phosphate, acyl or an amino acid residue, wherein at least one of R2 and R3 is acyl or an amino acid residue; X'is H or CH3; and Y is hydrogen, bromo, chloro, fluoro, iodo, NHZ or OH.
In a sixth principal embodiment, a compound of Formula VI, or a pharmaceutically acceptable salt or prodrug thereof, is provided: wherein: R', R2 and R3 are independently H, phosphate (including mono-, di-or triphosphate and a stabilized phosphate); straight chained, branched or cyclic alkyl (including lower alkyl) ; acyl
(including lower acyl) ; CO-alkyl, CO-aryl, CO-alkoxyalkyl, CO-aryloxyalkyl, CO- substituted aryl, sulfonate ester including alkyl or arylalkyl sulfonyl including methanesulfonyl and benzyl, wherein the phenyl group is optionally substituted with one or more substituents as described in the definition of aryl given herein; alkylsulfonyl, arylsulfonyl, aralkylsulfonyl, a lipid, including a phospholipid; an amino acid; and amino acid residue, a carbohydrate; a peptide; cholesterol ; or other pharmaceutically acceptable leaving group which when administered in vivo is capable of providing a compound wherein Rl, R2 and/or R3 is independently H or phosphate; wherein at least one of R2 and R3 is not hydrogen; Y is hydrogen, bromo, chloro, fluoro, iodo, OR4, NR4R5 or SR4 ; Xl is selected from the group consisting of H, straight chained, branched or cyclic alkyl, CO- alkyl, CO-aryl, CO-alkoxyalkyl, chloro, bromo, fluoro, iodo, oR4 NR4NR5 or SR5 ; and R4 and R5 are independently hydrogen, acyl (including lower acyl), or alkyl (including but not limited to methyl, ethyl, propyl and cyclopropyl).
In a preferred subembodiment, a compound of Formula VI, or a pharmaceutically acceptable salt or prodrug thereof, is provided wherein: R'is H or phosphate (preferably H) ; R2 and R3 are independently H, phosphate, acyl or an amino acid residue, wherein at least one of R2 and R3 is acyl or an amino acid residue; Xl is H or CH3 ; and Y is hydrogen, bromo, chloro, fluoro, iodo, NH2 or OH.
In a seventh principal embodiment, a compound selected from Formulas VII and VIII, or a pharmaceutically acceptable salt or prodrug thereof, is provided: Base Base R'O Rio x x R6 R6 ORZ OR3 ORZ (VII) (VIII) wherein:
Base is a purine or pyrimidine base as defined herein; R', R2 and R3 are independently H, phosphate (including mono-, di-or triphosphate and a stabilized phosphate); straight chained, branched or cyclic alkyl (including lower alkyl) ; acyl (including lower acyl) ; CO-alkyl, CO-aryl, CO-alkoxyalkyl, CO-aryloxyalkyl, CO- substituted aryl, sulfonate ester including alkyl or arylalkyl sulfonyl including methanesulfonyl and benzyl, wherein the phenyl group is optionally substituted with one or more substituents as described in the definition of aryl given herein; alkylsulfonyl, arylsulfonyl, aralkylsulfonyl, a lipid, including a phospholipid; an amino acid; and amino acid residue, a carbohydrate; a peptide; cholesterol; or other pharmaceutically acceptable leaving group which when administered in vivo is capable of providing a compound wherein R', R2 and/or R3 is independently H or phosphate; wherein R2 is not hydrogen; R6 is alkyl (including lower alkyl and halogenated alkyl), CH3, CF3, azido, cyano, alkenyl, <BR> <BR> <BR> alkynyl, Br-vinyl, 2-Br-ethyl,-C (O) O (alkyl), -C (O) O (lower alkyl),-O (acyl),-O (lower acyl), -O (alkyl),-O (lower alkyl),-O (alkenyl), CF3, chloro, bromo, fluoro, iodo, NO2, NH2,- NH (lower alkyl),-NH (acyl),-N (lower alkyl) 2, -N (acyl) 2; and X is O, S, SO2 or CH2.
In a first subembodiment, a compound of Formula VII or VIII, or a pharmaceutically acceptable salt or prodrug thereof, is provided wherein: Base is a purine or pyrimidine base as defined herein; R'is H or phosphate (preferably H); R2 and R3 are independently H, phosphate, acyl or an amino acid residue, wherein at least one of R2 and R3 is acyl or an amino acid residue; R6 is alkyl ; and X is O, S, SO2 or CH2.
In a second subembodiment, a compound of Formula VII or VIII, or a pharmaceutically acceptable salt or prodrug thereof, is provided wherein: Base is a purine or pyrimidine base as defined herein; R'is H or phosphate (preferably H);
R and R3 are independently H, phosphate, acyl or an amino acid residue, wherein at least one of R2 and R3 is an amino acid residue; R6 is alkyl ; and X is O, S, SO2 or CH2.
In a third subembodiment, a compound of Formula VII or VIII, or a pharmaceutically acceptable salt or prodrug thereof, is provided wherein: Base is a purine or pyrimidine base as defined herein; Rl is H or phosphate (preferably H); R2 and R3 are independently H, phosphate, acyl or an amino acid residue, wherein at least one of R 2and R3 is acyl or an amino acid residue; R6 is alkyl ; and X is 0.
In a eighth principal embodiment, a compound of Formulas IX and X, or a pharmaceutically acceptable salt or prodrug thereof, is provided: Rio Base Ri0 Base Rus rus X X ORz OR3 ORZ R7 (IX) (X) wherein: Base is a purine or pyrimidine base as defined herein; R', R and R3 are independently H, phosphate (including mono-, di-or triphosphate and a stabilized phosphate); straight chained, branched or cyclic alkyl (including lower alkyl) ; acyl (including lower acyl) ; CO-alkyl, CO-aryl, CO-alkoxyalkyl, CO-aryloxyalkyl, CO- substituted aryl, sulfonate ester including alkyl or arylalkyl sulfonyl including methanesulfonyl and benzyl, wherein the phenyl group is optionally substituted with one or more substituents as described in the definition of aryl given herein; alkylsulfonyl, arylsulfonyl, aralkylsulfonyl, a lipid, including a phospholipid ; an amino acid; and amino acid residue, a carbohydrate; a peptide; cholesterol; or other pharmaceutically acceptable
leaving group which when administered in vivo is capable of providing a compound wherein R', R2 and/or R3 is independently H or phosphate; wherein R2 is not hydrogen; R6 is alkyl (including lower alkyl and halogenated alkyl), CH3, CF3, azido, cyano, alkenyl, alkynyl, Br-vinyl, 2-Br-ethyl, -C(O)O(alkyl), -C(O)O(lower alkyl), -O(acyl), -O(lower acyl), -O(alkyl), -O(lower alkyl), -O(alkenyl), CF3, chloro, bromo, fluoro, iodo, NO2, NH2,- NH (lower alkyl),-NH (acyl),-N (lower alkyl) 2, -N (acyl) 2 ; and R7 is hydrogen, OR3, hydroxy, alkyl (including lower alkyl), azido, cyano, alkenyl, alkynyl, Br-vinyl,-C (O) O (alkyl),-C (O) O (lower alkyl),-O (acyl),-O (lower acyl),-O (alkyl),-O (lower <BR> <BR> <BR> <BR> alkyl),-O (alkenyl), chlorine, bromine, iodine, N02, NH2, -NH (lower alkyl),-NH (acyl),- N (lower alkyl) 2, -N (acyl) 2 ; and X is O, S, SO2 or CH2.
In a first subembodiment, a compound of Formula IX or X, or a pharmaceutically acceptable salt or prodrug thereof, is provided wherein: Base is a purine or pyrimidine base as defined herein; R'is H or phosphate (preferably H); R2 and R3 are independently H, phosphate, acyl or an amino acid residue, wherein at least one of R2 and R3 is acyl or an amino acid residue; R6 is alkyl ; and X is O, S, SO2 or CH2.
In a second subembodiment, a compound of Formula IX or X, or a pharmaceutically acceptable salt or prodrug thereof, is provided wherein: Base is a purine or pyrimidine base as defined herein; R'is H or phosphate (preferably H); R2 and R3 are independently H, phosphate, acyl or an amino acid residue, wherein at least one of R2 and R3 is an amino acid residue; R6 is alkyl ; and X is O, S, SO2 or CH2.
In a third subembodiment, a compound of Formula IX or X, or a pharmaceutically acceptable salt or prodrug thereof, is provided wherein: Base is a purine or pyrimidine base as defined herein; Rl is H or phosphate (preferably H) ; R2 and R3 are independently H, phosphate, acyl or an amino acid residue, wherein at least one of R2 and R3 is acyl or an amino acid residue; R6 is alkyl ; and XisO.
In another subembodiments, a compound of Formula X (a), or its pharmaceutically acceptable salt or prodrug, is provided: Base RIOX r__ X S oR2 (X (a)) wherein: Base is a purine or pyrimidine base as defined herein; optionally substituted with an amine or cyclopropyl (e. g. , 2-amino, 2,6-diamino or cyclopropyl guanosine); and R'and R2 are independently H, phosphate (including mono-, di-or triphosphate and a stabilized phosphate); straight chained, branched or cyclic alkyl (including lower alkyl) ; acyl (including lower acyl) ; CO-alkyl, CO-aryl, CO-alkoxyalkyl, CO-aryloxyalkyl, CO- substituted aryl, sulfonate ester including alkyl or arylalkyl sulfonyl including methanesulfonyl and benzyl, wherein the phenyl group is optionally substituted with one or more substituents as described in the definition of aryl given herein; alkylsulfonyl, arylsulfonyl, aralkylsulfonyl, a lipid, including a phospholipid ; an amino acid; and amino acid residue, a carbohydrate; a peptide; cholesterol ; or other pharmaceutically acceptable leaving group which when administered in vivo is capable of providing a compound wherein R', R2 and/or R3 is independently H or phosphate; wherein R2 is not hydrogen.
In a ninth principal embodiment a compound selected from Formulas XI and XII, or a pharmaceutically acceptable salt or prodrug thereof, is provided: R O Base R10 Base R6 R6 ""'0 Xi O C OR3 1R2 (XI) (XII)
wherein: Base is a purine or pyrimidine base as defined herein; Ri, R2 and R3 are independently H, phosphate (including mono-, di-or triphosphate and a stabilized phosphate); straight chained, branched or cyclic alkyl (including lower alkyl) ; acyl (including lower acyl) ; CO-alkyl, CO-aryl, CO-alkoxyalkyl, CO-aryloxyalkyl, CO- substituted aryl, sulfonate ester including alkyl or arylalkyl sulfonyl including methanesulfonyl and benzyl, wherein the phenyl group is optionally substituted with one or more substituents as described in the definition of aryl given herein; alkylsulfonyl, arylsulfonyl, aralkylsulfonyl, a lipid, including a phospholipid ; an amino acid; and amino acid residue, a carbohydrate; a peptide; cholesterol ; or other pharmaceutically acceptable leaving group which when administered in vivo is capable of providing a compound wherein Rl, R2 and/or R3 is independently H or phosphate; wherein R is not hydrogen; R6 is alkyl (including lower alkyl and halogenated alkyl), CH3, CF3, azido, cyano, alkenyl, alkynyl, Br-vinyl, 2-Br-ethyl,-C (O) O (alkyl),-C (O) O (lower alkyl),-O (acyl),-O (lower acyl), -O (alkyl),-O (lower alkyl),-O (alkenyl), CF3, chloro, bromo, fluoro, iodo, NO2, NH2, - NH (lower alkyl),-NH (acyl),-N (lower alkyl) 2, -N (acyl) 2; and X is O, S, SO2 or CH2.
In a first subembodiment, a compound of Formula XI or XII, or a pharmaceutically acceptable salt or prodrug thereof, is provided wherein: Base is a purine or pyrimidine base as defined herein; R'is H or phosphate (preferably H);
R'and W are independently H, phosphate, acyl or an amino acid residue, wherein at least one of R2 and R3 is acyl or an amino acid residue; R6 is alkyl ; and X is O, S, SO2 or CH2.
In a second subembodiment, a compound of Formula XI or XII, or a pharmaceutically acceptable salt or prodrug thereof, is provided wherein: Base is a purine or pyrimidine base as defined herein; Ru ils H or phosphate (preferably H); R2 and R3 are independently H, phosphate, acyl or an amino acid residue, wherein at least one of R2 and R3 is an amino acid residue; R6 is alkyl ; and X is O, S, SO2 or CH2.
In a third subembodiment, a compound of Formula XI or XII, or a pharmaceutically acceptable salt or prodrug thereof, is provided wherein: Base is a purine or pyrimidine base as defined herein; Ru ils H or phosphate (preferably H); R2 and R3 are independently H, phosphate, acyl or an amino acid residue, wherein at least one of R2 and R3 is acyl or an amino acid residue; R6 is alkyl ; and XisO.
In a tenth principal embodiment the invention provides a compound of Formula XIII, or a pharmaceutically acceptable salt or prodrug thereof : R'O Base Rio '**" !.' !.' Rus R9 (XIII) wherein:
Base is a purine or pyrimidine base as defined herein; R'is H, phosphate (including mono-, di-or triphosphate and a stabilized phosphate); straight chained, branched or cyclic alkyl (including lower alkyl) ; acyl (including lower acyl) ; CO- alkyl, CO-aryl, CO-alkoxyalkyl, CO-aryloxyalkyl, CO-substituted aryl, sulfonate ester including alkyl or arylalkyl sulfonyl including methanesulfonyl and benzyl, wherein the phenyl group is optionally substituted with one or more substituents as described in the definition of aryl given herein; alkylsulfonyl, arylsulfonyl, aralkylsulfonyl, a lipid, including a phospholipid; an amino acid; and amino acid residue, a carbohydrate; a peptide; cholesterol; or other pharmaceutically acceptable leaving group which when administered in vivo is capable of providing a compound wherein R'is H or phosphate; R6 is alkyl (including lower alkyl and halogenated alkyl), CH3, CF3, azido, cyano, alkenyl, <BR> <BR> <BR> alkynyl, Br-vinyl, 2-Br-ethyl,-C (O) O (alkyl), -C (O) O (lower alkyl),-O (acyl),-O (lower acyl), -O(alkyl), -O(lower alkyl), -O (alkenyl), CF3, chloro, bromo, fluoro, iodo, NO2, NH2, - NH (lower alkyl),-NH (acyl), -N (lower alkyl) 2,-N (acyl) 2; R7 and R9 are independently hydrogen, OR2, hydroxy, alkyl (including lower alkyl), azido, <BR> <BR> <BR> cyano, alkenyl, alkynyl, Br-vinyl,-C (O) O (alkyl), -C (O) O (lower alkyl),-O (acyl),-O (lower acyl),-O (alkyl),-O (lower alkyl),-O (alkenyl), chlorine, bromine, iodine, NO2, NH2, - NH (lower alkyl),-NH (acyl), -N (lower alkyl) 2, -N (acyl) 2 ; wherein at least one of R7 and R9 is OR2, wherein each R2 is independently phosphate (including mono-, di-or triphosphate and a stabilized phosphate); straight chained, branched or cyclic alkyl (including lower alkyl) ; acyl (including lower acyl) ; CO-alkyl, CO-aryl, CO- alkoxyalkyl, CO-aryloxyalkyl, CO-substituted aryl, sulfonate ester including alkyl or arylalkyl sulfonyl including methanesulfonyl and benzyl, wherein the phenyl group is optionally substituted with one or more substituents as described in the definition of aryl given herein; alkylsulfonyl, arylsulfonyl, aralkylsulfonyl, a lipid, including a phospholipid; an amino acid; and amino acid residue, a carbohydrate; a peptide; cholesterol; or other pharmaceutically acceptable leaving group which when administered in vivo is capable of providing a compound wherein R2 is H or phosphate; Rs and Rl° are independently H, alkyl (including lower alkyl), chlorine, bromine or iodine; alternatively, R7 and Rl°, R8 and R9, or R and Rl° can come together to form a pi bond; and X is O, S, S02 or CH2.
In a first subembodiment, a compound of Formula XIII, or its pharmaceutically acceptable salt or prodrug, is provided in which: (1) Base is a purine or pyrimidine base as defined herein; (2) RI is independently H or phosphate (including monophosphate, diphosphate, triphosphate, or a stabilized phosphate prodrug); acyl (including lower acyl) ; alkyl (including lower alkyl) ; sulfonate ester including alkyl or arylalkyl sulfonyl including methanesulfonyl and benzyl, wherein the phenyl group is optionally substituted with one or more substituents as described in the definition of aryl given herein; a lipid, including a phospholipid; an amino acid; a carbohydrate; a peptide; cholesterol; or other pharmaceutically acceptable leaving group which when administered in vivo is capable of providing a compound wherein R'is independently H or phosphate; (3) R6 is alkyl ; (4) R and R9 are independently OR2, alkyl, alkenyl, alkynyl, Br-vinyl, 0-alkenyl, chlorine, bromine, iodine, NO2, amino, lower alkylamino or di (loweralkyl) amino; wherein at least one of R7 and R9 is OR2 (and R2 is not hydrogen); (5) R8 and Rl° are independently H, alkyl (including lower alkyl), chlorine, bromine, or iodine; and (6) X is O, S, S02 or CH2.
In a second subembodiment, a compound of Formula XIII, or its pharmaceutically acceptable salt or prodrug, is provided in which: (1) Base is a purine or pyrimidine base as defined herein; (2) R'is independently H or phosphate (including monophosphate, diphosphate, triphosphate, or a stabilized phosphate prodrug); acyl (including lower acyl) ; alkyl (including lower alkyl) ; sulfonate ester including alkyl or arylalkyl sulfonyl including methanesulfonyl and benzyl, wherein the phenyl group is optionally substituted with one or more substituents as described in the definition of aryl given herein; a lipid, including a phospholipid; an amino acid; a carbohydrate; a peptide; cholesterol; or other pharmaceutically acceptable leaving group which when administered in vivo is capable of providing a compound wherein R'is independently H or phosphate; (3) R6 is alkyl, alkenyl, alkynyl, Br-vinyl, hydroxy, O-alkyl, 0-alkenyl, chloro, bromo, fluoro, iodo, NO2, amino, lower alkylamino, or di (loweralkyl) amino; (4) R7 and R9 are independently OH or OR, wherein at least one of R7 and R9 is OR2 (and R2 is not hydrogen); (5) R8 and Rl° are independently H, alkyl (including lower alkyl), chlorine, bromine, or iodine; and (6) X is O, S, SO2 or CH2.
In a third subembodiment, a compound of Formula XIII, or its pharmaceutically acceptable salt or prodrug, is provided in which: (1) Base is a purine or pyrimidine base as defined herein; (2) R'is independently H or phosphate (including monophosphate, diphosphate, triphosphate, or a stabilized phosphate prodrug); acyl (including lower acyl) ;
alkyl (including lower alkyl) ; sulfonate ester including alkyl or arylalkyl sulfonyl including methanesulfonyl and benzyl, wherein the phenyl group is optionally substituted with one or more substituents as described in the definition of aryl given herein; a lipid, including a phospholipid ; an amino acid; a carbohydrate; a peptide; cholesterol; or other pharmaceutically acceptable leaving group which when administered in vivo is capable of providing a compound wherein R'is independently H or phosphate; (3) R6 is alkyl, alkenyl, alkynyl, Br-vinyl, hydroxy, O-alkyl, O-alkenyl, chloro, bromo, fluoro, iodo, NO2, amino, lower alkylamino or di (loweralkyl) amino; (4) R7 and R9 are independently oR2, alkyl, alkenyl, alkynyl, Br-vinyl, O-alkenyl, chlorine, bromine, iodine, NO2, amino, lower alkylamino or di (loweralkyl) amino; wherein at least one of R'and R9 is OR2 (and R2 is not hydrogen); (5) R8 and Rl° are H; and (6) X is O, S, SO2 or CH2.
In a fourth subembodiment, a compound of Formula XIII, or its pharmaceutically acceptable salt or prodrug, is provided in which: (1) Base is a purine or pyrimidine base as defined herein; (2) R'is independently H or phosphate (including monophosphate, diphosphate, triphosphate, or a stabilized phosphate prodrug); acyl (including lower acyl) ; alkyl (including lower alkyl) ; sulfonate ester including alkyl or arylalkyl sulfonyl including methanesulfonyl and benzyl, wherein the phenyl group is optionally substituted with one or more substituents as described in the definition of aryl given herein; a lipid, including a phospholipid ; an amino acid; a carbohydrate; a peptide; cholesterol ; or other pharmaceutically acceptable leaving group which when administered in vivo is capable of providing a compound wherein R'is independently H or phosphate; (3) R6 is alkyl, alkenyl, alkynyl, Br-vinyl, hydroxy, O-alkyl, O-alkenyl, chloro, bromo, fluoro, iodo, N02, amino, lower alkylamino, or di (loweralkyl) amino; (4) R7 and R9 are independently OR2, alkyl, alkenyl, alkynyl, Br-vinyl, O-alkenyl, chlorine, bromine, iodine, NO2, amino, lower alkylamino, or di (loweralkyl) amino; wherein at least one of R7 and R9is oR2 (and R2 is not hydrogen); (5) R 8 and Rl° are independently H, alkyl (including lower alkyl), chlorine, bromine, or iodine; and (6) X is O.
In a fifth subembodiment, a compound of Formula XIII, or its pharmaceutically acceptable salt or prodrug, is provided in which: (1) Base is a purine or pyrimidine base as defined herein; (2) R'is independently H or phosphate (including monophosphate, diphosphate, triphosphate, or a stabilized phosphate prodrug); acyl (including lower acyl) ; alkyl (including lower alkyl) ; sulfonate ester including alkyl or arylalkyl sulfonyl including methanesulfonyl and benzyl, wherein the phenyl group is optionally substituted with one or
more substituents as described in the definition of aryl given herein; a lipid, including a phospholipid ; an amino acid; a carbohydrate; a peptide; cholesterol; or other pharmaceutically acceptable leaving group which when administered in vivo is capable of providing a compound wherein R'is independently H or phosphate; (3) R6 is alkyl ; (4) R7 and R9 are independently OH or OR, wherein at least one of R and R9 is OR (and R2 is not hydrogen); (5) R8 and Rl° are independently H, alkyl (including lower alkyl), chlorine, bromine or iodine; and (6) X is O, S, SO2 or CH2.
In a sixth subembodiment, a compound of Formula XIII, or its pharmaceutically acceptable salt or prodrug, is provided in which: (1) Base is a purine or pyrimidine base as defined herein; (2) Rl is independently H or phosphate (including monophosphate, diphosphate, triphosphate, or a stabilized phosphate prodrug); acyl (including lower acyl) ; alkyl (including lower alkyl) ; sulfonate ester including alkyl or arylalkyl sulfonyl including methanesulfonyl and benzyl, wherein the phenyl group is optionally substituted with one or more substituents as described in the definition of aryl given herein; a lipid, including a phospholipid ; an amino acid; a carbohydrate; a peptide; cholesterol; or other pharmaceutically acceptable leaving group which when administered in vivo is capable of providing a compound wherein R'is independently H or phosphate; (3) R6 is alkyl ; (4) R7 and R9 are independently OR2, alkyl (including lower alkyl), alkenyl, alkynyl, Br-vinyl, O- alkenyl, chlorine, bromine, iodine, NO2, amino, lower alkylamino, or di (loweralkyl) amino; wherein at least one of R7 and R9 is OR2 (and W is not hydrogen); (5) R8 and Rl° are H; and (6) X is O, S, S02, or CH2.
In a seventh subembodiment, a compound of Formula XIII, or its pharmaceutically acceptable salt or prodrug, is provided in which: (1) Base is a purine or pyrimidine base as defined herein; (2) R'is independently H or phosphate (including monophosphate, diphosphate, triphosphate, or a stabilized phosphate prodrug); acyl (including lower acyl) ; alkyl (including lower alkyl) ; sulfonate ester including alkyl or arylalkyl sulfonyl including methanesulfonyl and benzyl, wherein the phenyl group is optionally substituted with one or more substituents as described in the definition of aryl given herein; a lipid, including a phospholipid; an amino acid; a carbohydrate; a peptide; cholesterol; or other pharmaceutically acceptable leaving group which when administered in vivo is capable of providing a compound wherein RI is independently H or phosphate; (3) R6 is alkyl ; (4) R7 and R9 are independently OR2, alkyl (including lower alkyl), alkenyl, alkynyl, Br-vinyl, O- alkenyl, chlorine, bromine, iodine, NO2, amino, lower alkylamino or di (loweralkyl) amino;
wherein at least one of R7 and R9 is OR2 (and R2 is not hydrogen); (5) R8 and Rl° are independently H, alkyl (including lower alkyl), chlorine, bromine or iodine; and (6) X is O.
In a eighth subembodiment, a compound of Formula XIII, or its pharmaceutically acceptable salt or prodrug, is provided in which: (1) Base is a purine or pyrimidine base as defined herein; (2) R'is independently H or phosphate (including monophosphate, diphosphate, triphosphate, or a stabilized phosphate prodrug); acyl (including lower acyl) ; alkyl (including lower alkyl) ; sulfonate ester including alkyl or arylalkyl sulfonyl including methanesulfonyl and benzyl, wherein the phenyl group is optionally substituted with one or more substituents as described in the definition of aryl given herein; a lipid, including a phospholipid ; an amino acid; a carbohydrate; a peptide; cholesterol ; or other pharmaceutically acceptable leaving group which when administered in vivo is capable of providing a compound wherein Rl is independently H or phosphate; (3) R6 is alkyl (including lower alkyl), alkenyl, alkynyl, Br-vinyl, hydroxy, O-alkyl, O-alkenyl, chloro, bromo, fluoro, iodo, N02, amino, lower alkylamino or di (loweralkyl) amino; (4) R 7and R9 are independently OH or OR, wherein at least one of R7 and R9 is OR (and R2 is not hydrogen); (5) R8 and Rlo are hydrogen; and (6) X is O, S, SO2 or CH2.
In a ninth subembodiment, a compound of Formula XIII, or its pharmaceutically acceptable salt or prodrug, is provided in which: (1) Base is a purine or pyrimidine base as defined herein; (2) Rl is independently H or phosphate (including monophosphate, diphosphate, triphosphate, or a stabilized phosphate prodrug); acyl (including lower acyl) ; alkyl (including lower alkyl) ; sulfonate ester including alkyl or arylalkyl sulfonyl including methanesulfonyl and benzyl, wherein the phenyl group is optionally substituted with one or more substituents as described in the definition of aryl given herein; a lipid, including a phospholipid ; an amino acid; a carbohydrate; a peptide; cholesterol; or other pharmaceutically acceptable leaving group which when administered in vivo is capable of providing a compound wherein R'is independently H or phosphate; (3) R6 is alkyl (including lower alkyl), alkenyl, alkynyl, Br-vinyl, hydroxy, O-alkyl, O-alkenyl, chloro, bromo, fluoro, iodo, NO2, amino, lower alkylamino or di (loweralkyl) amino; (4) R 7and R9 are independently OH or OR2, wherein at least one of R7 and R9 is oR2 (and R2 is not hydrogen); (5) R8 and RIO are independently H, alkyl (including lower alkyl), chlorine, bromine or iodine; and (6) X is 0.
In a tenth preferred subembodiment, a compound of Formula XIII, or its pharmaceutically acceptable salt or prodrug, is provided in which: (1) Base is a purine or
pyrimidine base as defined herein; (2) R'is independently H or phosphate (including monophosphate, diphosphate, triphosphate, or a stabilized phosphate prodrug); acyl (including lower acyl) ; alkyl (including lower alkyl) ; sulfonate ester including alkyl or arylalkyl sulfonyl including methanesulfonyl and benzyl, wherein the phenyl group is optionally substituted with one or more substituents as described in the definition of aryl given herein; a lipid, including a phospholipid ; an amino acid; a carbohydrate; a peptide; cholesterol ; or other pharmaceutically acceptable leaving group which when administered in vivo is capable of providing a compound wherein R'is independently H or phosphate; (3) R6 is alkyl (including lower alkyl), alkenyl, alkynyl, Br-vinyl, hydroxy, O-alkyl, O-alkenyl, chloro, bromo, fluoro, iodo, N02, amino, lower alkylamino or di (loweralkyl) amino; (4) R7 and R9 are independently OR2, alkyl (including lower alkyl), alkenyl, alkynyl, Br-vinyl, O- alkenyl, chlorine, bromine, iodine, NO2, amino, lower alkylamino, or di (loweralkyl) amino; wherein at least one of R7 and R9 is OR2 (and R2 is not hydrogen); (5) R8 and Rl° are hydrogen; and (6) X is O.
In an eleventh subembodiment, a compound of Formula XIII, or its pharmaceutically acceptable salt or prodrug, is provided in which: (1) Base is a purine or pyrimidine base as defined herein; (2) R'is independently H or phosphate; (3) R6 is alkyl (including lower alkyl), alkenyl, alkynyl, Br-vinyl, hydroxy, O-alkyl, O-alkenyl, chloro, bromo, fluoro, iodo, NO2, amino, lower alkylamino or di (loweralkyl) amino; (4) R7 and R9 are independently OH or OR, wherein at least one of R and R9 is OR (and R2 is not hydrogen); (5) R8 and R10 are hydrogen; and (6) X is O, S, SO2 or CH2.
In a twelfth subembodiment, a compound of Formula XIII, or its pharmaceutically acceptable salt or prodrug, is provided in which: (1) Base is a purine or pyrimidine base as defined herein; (2) R'is independently H or phosphate; (3) R6 is alkyl ; (4) R 7and R9 are independently OH or OR, wherein at least one of R and R9 is OR2 (and R2 is not hydrogen); (5) R8 and Rl° are hydrogen; and (6) X is O, S, SO2, or CH2.
In a thirteenth subembodiment, a compound of Formula XIII, or its pharmaceutically acceptable salt or prodrug, is provided in which: (1) Base is a purine or pyrimidine base as defined herein; (2) R'is independently H or phosphate; (3) R6 is alkyl ; (4) R 7and R9 are independently OH or OR, wherein at least one of R and R9 is OR (and R2 is not hydrogen); (5) R8 and Rl° are independently H, alkyl (including lower alkyl), chlorine, bromine, or iodine; and (6) X is O.
In a fourteenth subembodiment, a compound of Formula XIII, or its pharmaceutically acceptable salt or prodrug, is provided in which: (1) Base is a purine or pyrimidine base as defined herein; (2) R'is independently H or phosphate; (3) R6 is alkyl ; (4) R7 and R9 are independently OR2, alkyl (including lower alkyl), alkenyl, alkynyl, Br-vinyl, O-alkenyl, chlorine, bromine, iodine, NO2, amino, lower alkylamino or di (loweralkyl) amino; wherein at least one of R7 and R9 is OR2 (and R2 is not hydrogen); (5) R8 and RIO are hydrogen; and (6) XisO.
In other subembodiments, a compound of Formula XIII, or its pharmaceutically acceptable salt or prodrug, is provided in which: (1) Base is adenine; (2) R'is hydrogen; (3) R6 is methyl; (4) R7 is hydroxyl (5) R9 is L-valinyl ; (6) R8 and Rl° are hydrogen; and (7) X is O ; (1) Base is guanine; (2) R'is hydrogen; (3) R6 is methyl ; (4) R7 is hydroxyl (5) R9 is L-valinyl ; (6) R8 and Rl° are hydrogen; and (7) X is O ; (1) Base is cytosine; (2) R'is hydrogen; (3) R6 is methyl ; (4) R7 is hydroxyl (5) R9 is L-valinyl ; (6) R8 and Rl° are hydrogen; and (7) X is O ; (1) Base is thymidine; (2) R'is hydrogen; (3) R6 is methyl ; (4) R7 is hydroxyl (5) R9 is L-valinyl ; (6) R8 and R10 are hydrogen; and (7) X is O ; (1) Base is uracil ; (2) Rl is hydrogen; (3) R6 is methyl ; (4) R7 is hydroxyl (5) R9 is L- valinyl ; (6) R8 and RIO are hydrogen; and (7) X is O ; (1) Base is adenine; (2) R'is phosphate; (3) R6 is methyl ; (4) R7 is hydroxyl (5) R9 is L-valinyl ; (6) R8 and R10 are hydrogen; and (7) X is O ; (1) Base is adenine; (2) R'is hydrogen; (3) R6 is ethyl ; (4) R7 is hydroxyl (5) R9 is L- valinyl ; (6) R8 and R10 are hydrogen; and (7) X is O ; (1) Base is adenine; (2) R'is hydrogen; (3) R6 is propyl ; (4) R7 is hydroxyl (5) R9 is L-valinyl ; (6) R8 and R10 are hydrogen; and (7) X is O ; (1) Base is adenine; (2) R'is hydrogen; (3) R6 is butyl ; (4) R7 is hydroxyl (5) R9 is L- valinyl ; (6) R8 and R10 are hydrogen; and (7) X is O ; (1) Base is adenine; (2) R'is hydrogen; (3) R6 is methyl ; (4) R7 is hydrogen (5) R9 is L-valinyl ; (6) R8 and R10 are hydrogen; and (7) X is O ;
(1) Base is adenine; (2) R'is hydrogen; (3) R6 is methyl ; (4) R7 is hydroxyl (5) R9 is L-valinyl ; (6) R8 and Rl° are hydrogen; and (7) X is S; (1) Base is adenine; (2) R'is hydrogen; (3) R6 is methyl ; (4) R7 is hydroxyl (5) R9 is L-valinyl ; (6) R8 and Rl° are hydrogen; and (7) X is SO2 ; (1) Base is adenine; (2) R'is hydrogen; (3) R6 is methyl ; (4) R7 is hydroxyl (5) R9 is L-valinyl ; (6) R8 and R° are hydrogen; and (7) X is CH2.
In a eleventh principal embodiment the invention provides a compound of Formula XIV, or a pharmaceutically acceptable salt or prodrug thereof : R'O Base ) Rl° R6 1 i"i7 RnR7 (XIV) wherein: Base is a purine or pyrimidine base as defined herein; R'is H, phosphate (including mono-, di-or triphosphate and a stabilized phosphate); straight chained, branched or cyclic alkyl (including lower alkyl) ; acyl (including lower acyl) ; CO- alkyl, CO-aryl, CO-alkoxyalkyl, CO-aryloxyalkyl, CO-substituted aryl, sulfonate ester including alkyl or arylalkyl sulfonyl including methanesulfonyl and benzyl, wherein the phenyl group is optionally substituted with one or more substituents as described in the definition of aryl given herein; alkylsulfonyl, arylsulfonyl, aralkylsulfonyl, a lipid, including a phospholipid ; an amino acid; and amino acid residue, a carbohydrate; a peptide; cholesterol ; or other pharmaceutically acceptable leaving group which when administered in vivo is capable of providing a compound wherein R'is H or phosphate; R6 is alkyl (including lower alkyl and halogenated alkyl), CH3, CF3, azido, cyano, alkenyl, alkynyl, Br-vinyl, 2-Br-ethyl,-C (O) O (alkyl),-C (O) O (lower alkyl),-O (acyl),-O (lower acyl), -O(alkyl), -O(lower alkyl), -O(alkenyl), CF3, chloro, bromo, fluoro, iodo, NO2, NH2,- NH (lower alkyl),-NH (acyl),-N (lower alkyl) 2, -N (acyl) 2; R7 and R9 are independently hydrogen, OR2, hydroxy, alkyl (including lower alkyl), azido, cyano, alkenyl, alkynyl, Br-vinyl,-C (O) O (alkyl),-C (O) O (lower alkyl),-O (acyl),-O (lower
acyl),-O (alkyl),-O (lower alkyl),-O (alkenyl), chlorine, bromine, iodine, N02, NH2, -NH (lower alkyl),-NH (acyl),-N (lower alkyl) 2,-N (acyl) 2 ; wherein at least one of R7 and R9 is OR2, wherein each R is independently phosphate (including mono-, di-or triphosphate and a stabilized phosphate); straight chained, branched or cyclic alkyl (including lower alkyl) ; acyl (including lower acyl) ; CO-alkyl, CO-aryl, CO- alkoxyalkyl, CO-aryloxyalkyl, CO-substituted aryl, sulfonate ester including alkyl or arylalkyl sulfonyl including methanesulfonyl and benzyl, wherein the phenyl group is optionally substituted with one or more substituents as described in the definition of aryl given herein; alkylsulfonyl, arylsulfonyl, aralkylsulfonyl, a lipid, including a phospholipid ; an amino acid; and amino acid residue, a carbohydrate; a peptide; cholesterol ; or other pharmaceutically acceptable leaving group which when administered in vivo is capable of providing a compound wherein R is H or phosphate; R'° is H, alkyl (including lower alkyl), chlorine, bromine or iodine; alternatively, or R7 and Rl° can come together to form a pi bond; and X is O, S, SO2 or CH2.
In a first subembodiment, a compound of Formula XIV, or its pharmaceutically acceptable salt or prodrug, is provided in which: (1) Base is a purine or pyrimidine base as defined herein; (2) R'is independently H; phosphate (including monophosphate, diphosphate, triphosphate, or a stabilized phosphate prodrug); acyl (including lower acyl) ; alkyl (including lower alkyl) ; sulfonate ester including alkyl or arylalkyl sulfonyl including methanesulfonyl and benzyl, wherein the phenyl group is optionally substituted with one or more substituents as described in the definition of aryl given herein; a lipid, including a phospholipid; an amino acid; a carbohydrate; a peptide; cholesterol ; or other pharmaceutically acceptable leaving group which when administered in vivo is capable of providing a compound wherein R'is independently H or phosphate; (3) R6 is alkyl (including lower alkyl), alkenyl, alkynyl, Br- vinyl, hydroxy, O-alkyl, O-alkenyl, chloro, bromo, fluoro, iodo, N02, amino, lower alkylamino, or di (loweralkyl) amino; (4) R7 and R9 are independently hydrogen, OR2, alkyl (including lower alkyl), alkenyl, alkynyl, Br-vinyl, O-alkenyl, chlorine, bromine, iodine, NO2, amino, lower alkylamino or di (loweralkyl)-amino ; wherein at least one of R7 and R9 is oR2 (and R2 is not hydrogen); (5) Rio ils H; and (6) X is O, S, SO2, or CH2.
In a second subembodiment, a compound of Formula XIV, or its pharmaceutically acceptable salt or prodrug, is provided in which: (1) Base is a purine or pyrimidine base as
defined herein; (2) R'is independently H; phosphate (including monophosphate, diphosphate, triphosphate, or a stabilized phosphate prodrug); acyl (including lower acyl) ; alkyl (including lower alkyl) ; sulfonate ester including alkyl or arylalkyl sulfonyl including methanesulfonyl and benzyl, wherein the phenyl group is optionally substituted with one or more substituents as described in the definition of aryl given herein; a lipid, including a phospholipid; an amino acid ; a carbohydrate ; a peptide; cholesterol; or other pharmaceutically acceptable leaving group which when administered in vivo is capable of providing a compound wherein R'is independently H or phosphate; (3) R6 is alkyl (including lower alkyl), alkenyl, alkynyl, Br- vinyl, hydroxy, O-alkyl, 0-alkenyl, chloro, bromo, fluoro, iodo, NO2, amino, lower alkylamino or di (loweralkyl) amino; (4) R and R9 are independently OH or OR2, wherein at least one of R7 and R9 is OR2 (and R2 is not hydrogen); (5) Rl° is H, alkyl (including lower alkyl), chlorine, bromine, or iodine; and (6) X is O, S, SO2 or CH2.
In a third subembodiment, a compound of Formula XIV, or its pharmaceutically acceptable salt or prodrug, is provided in which: (1) Base is a purine or pyrimidine base as defined herein; (2) R'is independently H; phosphate (including monophosphate, diphosphate, triphosphate, or a stabilized phosphate prodrug); acyl (including lower acyl) ; alkyl (including lower alkyl) ; sulfonate ester including alkyl or arylalkyl sulfonyl including methanesulfonyl and benzyl, wherein the phenyl group is optionally substituted with one or more substituents as described in the definition of aryl given herein; a lipid, including a phospholipid; an amino acid; a carbohydrate; a peptide; cholesterol; or other pharmaceutically acceptable leaving group which when administered in vivo is capable of providing a compound wherein R'is independently H or phosphate; (3) R6 is alkyl (including lower alkyl), alkenyl, alkynyl, Br- vinyl, hydroxy, O-alkyl, 0-alkenyl, chloro, bromo, fluoro, iodo, N02, amino, lower alkylamino, or di (loweralkyl) amino; (4) R7 and R9 are independently hydrogen, OR2, alkyl (including lower alkyl), alkenyl, alkynyl, Br-vinyl, 0-alkenyl, chlorine, bromine, iodine, NO2, amino, lower alkylamino or di (loweralkyl) -amino ; wherein at least one of R7 and R9 is OR2 (and R2 is not hydrogen); (5) Rl° is H, alkyl (including lower alkyl), chlorine, bromine or iodine; and (6) X is O.
In a fourth subembodiment, a compound of Formula XIV, or its pharmaceutically acceptable salt or prodrug, is provided in which: (1) Base is a purine or pyrimidine base as defined herein; (2) R'is independently H; phosphate (including monophosphate, diphosphate, triphosphate, or a stabilized phosphate prodrug); acyl (including lower acyl) ; alkyl (including lower alkyl) ; sulfonate ester including alkyl or arylalkyl sulfonyl including methanesulfonyl
and benzyl, wherein the phenyl group is optionally substituted with one or more substituents as described in the definition of aryl given herein; a lipid, including a phospholipid; an amino acid; a carbohydrate; a peptide; cholesterol; or other pharmaceutically acceptable leaving group which when administered in vivo is capable of providing a compound wherein Ru ils independently H or phosphate; (3) R6 is alkyl (including lower alkyl), alkenyl, alkynyl, Br- vinyl, hydroxy, O-alkyl, O-alkenyl, chloro, bromo, fluoro, iodo, NO2, amino, lower alkylamino or di (loweralkyl) amino; (4) R and R9 are independently OH or OR2, wherein at least one of R7 and R9 is OR2 (and R2 is not hydrogen); (5) Rl° is H; and (6) X is O, S, SO2 or CH2.
In a fifth subembodiment, a compound of Formula XIV, or its pharmaceutically acceptable salt or prodrug, is provided in which: (1) Base is a purine or pyrimidine base as defined herein; (2) RI is independently H; phosphate (including monophosphate, diphosphate, triphosphate, or a stabilized phosphate prodrug); acyl (including lower acyl) ; alkyl (including lower alkyl) ; sulfonate ester including alkyl or arylalkyl sulfonyl including methanesulfonyl and benzyl, wherein the phenyl group is optionally substituted with one or more substituents as described in the definition of aryl given herein; a lipid, including a phospholipid; an amino acid; a carbohydrate; a peptide; cholesterol; or other pharmaceutically acceptable leaving group which when administered in vivo is capable of providing a compound wherein RI is independently H or phosphate; (3) R6 is alkyl (including lower alkyl), alkenyl, alkynyl, Br- vinyl, hydroxy, O-alkyl, O-alkenyl, chloro, bromo, fluoro, iodo, NO2, amino, lower alkylamino or di (loweralkyl) amino; (4) R and R9 are independently OH or OR2, wherein at least one of R7 and R9 is OR2 (and R2 is not hydrogen); (5) Rio ils H, alkyl (including lower alkyl), chlorine, bromine or iodine; and (6) X is O.
In a sixth subembodiment, a compound of Formula XIV, or its pharmaceutically acceptable salt or prodrug, is provided in which: (1) Base is a purine or pyrimidine base as defined herein; (2) R'is independently H; phosphate (including monophosphate, diphosphate, triphosphate, or a stabilized phosphate prodrug); acyl (including lower acyl) ; alkyl (including lower alkyl) ; sulfonate ester including alkyl or arylalkyl sulfonyl including methanesulfonyl and benzyl, wherein the phenyl group is optionally substituted with one or more substituents as described in the definition of aryl given herein; a lipid, including a phospholipid; an amino acid; a carbohydrate; a peptide; cholesterol; or other pharmaceutically acceptable leaving group which when administered in vivo is capable of providing a compound wherein R'is independently H or phosphate; (3) R6 is alkyl (including lower alkyl), alkenyl, alkynyl, Br-
vinyl, hydroxy, O-alkyl, O-alkenyl, chloro, bromo, fluoro, iodo, NO2, amino, lower alkylamino, or di (loweralkyl) amino; (4) R7 and R9 are independently hydrogen, OR2, alkyl (including lower alkyl), alkenyl, alkynyl, Br-vinyl, 0-alkenyl, chlorine, bromine, iodine, NOz, amino, lower alkylamino, or di (loweralkyl) amino; wherein at least one of R7 and R9 is oR2 (and R2 is not hydrogen); (5) Rio ils H; and (6) X is O.
In a seventh subembodiment, a compound of Formula XIV, or its pharmaceutically acceptable salt or prodrug, is provided in which: (1) Base is a purine or pyrimidine base as defined herein; (2) R'is independently H; phosphate (including monophosphate, diphosphate, triphosphate, or a stabilized phosphate prodrug); acyl (including lower acyl) ; alkyl (including lower alkyl) ; sulfonate ester including alkyl or arylalkyl sulfonyl including methanesulfonyl and benzyl, wherein the phenyl group is optionally substituted with one or more substituents as described in the definition of aryl given herein; a lipid, including a phospholipid ; an amino acid; a carbohydrate; a peptide; cholesterol; or other pharmaceutically acceptable leaving group which when administered in vivo is capable of providing a compound wherein R'is independently H or phosphate; (3) R6 is alkyl (including lower alkyl), alkenyl, alkynyl, Br- vinyl, hydroxy, O-alkyl, O-alkenyl, chloro, bromo, fluoro, iodo, NO2, amino, lower alkylamino, or di (loweralkyl) amino; (4) R7 and R9 are independently OH or OR2, wherein at least one of R7 and R9 is OR2 (and W is not hydrogen); (5) Rio ils H; and (6) X is O.
In an eighth subembodiment, a compound of Formula XIV, or its pharmaceutically acceptable salt or prodrug, is provided in which: (1) Base is a purine or pyrimidine base as defined herein; (2) R'is independently H or phosphate; (3) R6 is alkyl ; (4) R7 and R9 are independently hydrogen, OR2, alkyl (including lower alkyl), alkenyl, alkynyl, Br-vinyl, O- alkenyl, chlorine, bromine, iodine, NO2, amino, lower alkylamino or di (loweralkyl)-amino ; wherein at least one of R7 and R9 is OR2 (and R2 is not hydrogen); (5) R10 is H, alkyl (including lower alkyl), chlorine, bromine or iodine; and (6) X is O, S, SO2, or CH2.
In a ninth subembodiment, a compound of Formula XIV, or its pharmaceutically acceptable salt or prodrug, is provided in which: (1) Base is a purine or pyrimidine base as defined herein; (2) R'is independently H or phosphate; (3) R6 is alkyl (including lower alkyl), alkenyl, alkynyl, Br-vinyl, hydroxy, O-alkyl, 0-alkenyl, chloro, bromo, fluoro, iodo, NO2, amino, lower alkylamino, or di (loweralkyl) amino; (4) R7 and R9 are independently OH or OR, wherein at least one of R7 and R9 is OR2 (and R2 is not hydrogen); (5) Rio ils H; and (6) X is O, S, SO2, or CH2.
In a tenth preferred subembodiment, a compound of Formula XIV, or its pharmaceutically acceptable salt or prodrug, is provided in which: (1) Base is a purine or pyrimidine base as defined herein; (2) Rl is independently H or phosphate; (3) R6 is alkyl ; (4) R 7and R9 are independently OH or OR2, wherein at least one of R7 and R9 is oR2 (and R2 is not hydrogen); (5) R10 is H; and (6) X is O, S, SO2, or CH2.
In even more preferred subembodiments, a compound of Formula XIV, or its pharmaceutically acceptable salt or prodrug, is provided in which: (1) Base is adenine; (2) R'is hydrogen; (3) R6 is methyl ; (4) R7 is hydroxyl (5) R9 is L-valinyl ; (6) Rl° is hydrogen; and (7) X is O ; (1) Base is guanine; (2) R'is hydrogen; (3) R6 is methyl ; (4) R7 is hydroxyl (5) R9 is L-valinyl ; (6) R10 is hydrogen; and (7) X is O ; (1) Base is cytosine; (2) Rl is hydrogen; (3) R6 is methyl ; (4) R7 is hydroxyl (5) R9 is L-valinyl ; (6) R10 is hydrogen; and (7) X is O ; (1) Base is thymidine; (2) R'is hydrogen; (3) R6 is methyl; (4) R7 is hydroxyl (5) R9 is L-valinyl ; (6) R10 is hydrogen; and (7) X is O ; (1) Base is uracil ; (2) R'is hydrogen; (3) R6 is methyl ; (4) R7 is hydroxyl (5) R9 is L- valinyl ; (6) Rl° is hydrogen; and (7) X is O ; (1) Base is adenine; (2) Rl is phosphate; (3) R6 is methyl ; (4) R7 is hydroxyl (5) R9 is L-valinyl ; (6) R'° is hydrogen; and (7) X is O ; (1) Base is adenine; (2) R'is hydrogen; (3) R6 is ethyl ; (4) R7 is hydroxyl (5) R9 is L- valinyl ; (6) Rl°is hydrogen; and (7) X is O ; (1) Base is adenine; (2) R'is hydrogen; (3) R6 is propyl ; (4) R7 is hydroxyl (5) R9 is L-valinyl ; (6) Rl° is hydrogen; and (7) X is O ; (1) Base is adenine; (2) R'is hydrogen; (3) R6 is butyl ; (4) R7 is hydroxyl (5) R9 is L- valinyl ; (6) R10 is hydrogen; and (7) X is O ; (1) Base is adenine; (2) Rl is hydrogen; (3) R6 is methyl ; (4) R7 is hydroxyl (5) R9 is L-valinyl ; (6) Rl° is hydrogen; and (7) X is S; (1) Base is adenine; (2) R'is hydrogen; (3) R6 is methyl ; (4) R7 is hydroxyl (5) R9 is L-valinyl ; (6) Rl° is hydrogen; and (7) X is SO2 ; or I u #@ (1) Base is adenine; (2) R'is hydrogen; (3) R6 is methyl ; (4) R7 is hydroxyl (5) R9 is L-valinyl ; (6) Rl° is hydrogen; and (7) X is CH2.
In an twelfth principal embodiment, the invention provides a compound of Formula XV, or a pharmaceutically acceptable salt or prodrug thereof :
wherein: Base is a purine or pyrimidine base as defined herein; Rl is H, phosphate (including mono-, di-or triphosphate and a stabilized phosphate); straight chained, branched or cyclic alkyl (including lower alkyl) ; acyl (including lower acyl) ; CO- alkyl, CO-aryl, CO-alkoxyalkyl, CO-aryloxyalkyl, CO-substituted aryl, sulfonate ester including alkyl or arylalkyl sulfonyl including methanesulfonyl and benzyl, wherein the phenyl group is optionally substituted with one or more substituents as described in the definition of aryl given herein; alkylsulfonyl, arylsulfonyl, aralkylsulfonyl, a lipid, including a phospholipid ; an amino acid; and amino acid residue, a carbohydrate; a peptide; cholesterol; or other pharmaceutically acceptable leaving group which when administered in vivo is capable of providing a compound wherein R'is H or phosphate; R6 is alkyl (including lower alkyl and halogenated alkyl), CH3, CF3, azido, cyano, alkenyl, <BR> <BR> <BR> alkynyl, Br-vinyl, 2-Br-ethyl,-C (O) O (alkyl),-C (O) O (lower alkyl),-O (acyl),-O (lower acyl), -O(alkyl), -O(lower alkyl), -O(alkenyl), CF3, chloro, bromo, fluoro, iodo, NO2, NH2,- NH (lower alkyl),-NH (acyl),-N (lower alkyl) 2, -N (acyl) 2 ; R7 and R9 are independently hydrogen, OR2, hydroxy, alkyl (including lower alkyl), azido, <BR> <BR> <BR> cyano, alkenyl, alkynyl, Br-vinyl, -C (O) O (alkyl),-C (O) O (lower alkyl),-O (acyl),-O (lower acyl),-O (alkyl),-O (lower alkyl),-O (alkenyl), chlorine, bromine, iodine, NO2, NH2, -NH (lower alkyl),-NH (acyl),-N (lower alkyl) 2, -N (acyl)2 ; wherein at least one of R7 and R9 is OR2, wherein each R2 is independently phosphate (including mono-, di-or triphosphate and a stabilized phosphate); straight chained, branched
or cyclic alkyl (including lower alkyl) ; acyl (including lower acyl) ; CO-alkyl, CO-aryl, CO- alkoxyalkyl, CO-aryloxyalkyl, CO-substituted aryl, sulfonate ester including alkyl or arylalkyl sulfonyl including methanesulfonyl and benzyl, wherein the phenyl group is optionally substituted with one or more substituents as described in the definition of aryl given herein; alkylsulfonyl, arylsulfonyl, aralkylsulfonyl, a lipid, including a phospholipid; an amino acid; and amino acid residue, a carbohydrate; a peptide; cholesterol; or other pharmaceutically acceptable leaving group which when administered in vivo is capable of providing a compound wherein R2 is H or phosphate; R is H, alkyl (including lower alkyl), chlorine, bromine or iodine; alternatively, R8 and R9 can come together to form a pi bond; X is O, S, SO2 or CH2.
In a first subembodiment, a compound of Formula XV, or its pharmaceutically acceptable salt or prodrug, is provided in which: (1) Base is a purine or pyrimidine base as defined herein; (2) R'is independently H; phosphate (including monophosphate, diphosphate, triphosphate, or a stabilized phosphate prodrug); acyl (including lower acyl) ; alkyl (including lower alkyl) ; sulfonate ester including alkyl or arylalkyl sulfonyl including methanesulfonyl and benzyl, wherein the phenyl group is optionally substituted with one or more substituents as described in the definition of aryl given herein; a lipid, including a phospholipid ; an amino acid; a carbohydrate; a peptide; cholesterol; or other pharmaceutically acceptable leaving group which when administered in vivo is capable of providing a compound wherein R'is independently H or phosphate; (3) R6 is alkyl ; (4) R7 and R9 are independently hydrogen, OR2, alkyl (including lower alkyl), alkenyl, alkynyl, Br-vinyl, 0-alkenyl, chlorine, bromine, iodine, NO2, amino, lower alkylamino or di (loweralkyl) amino; wherein at least one of and R9 is oR2 (and W is not hydrogen); (5) R8 is H, alkyl (including lower alkyl), chlorine, bromine or iodine; and (6) X is O, S, SO2 or CH2.
In a second subembodiment, a compound of Formula XV, or its pharmaceutically acceptable salt or prodrug, is provided in which: (1) Base is a purine or pyrimidine base as defined herein; (2) R'is independently H; phosphate (including monophosphate, diphosphate, triphosphate, or a stabilized phosphate prodrug); acyl (including lower acyl) ; alkyl (including lower alkyl) ; sulfonate ester including alkyl or arylalkyl sulfonyl including methanesulfonyl and benzyl, wherein the phenyl group is optionally substituted with one or more substituents as described in the definition of aryl given herein; a lipid, including a phospholipid ; an amino
acid; a carbohydrate; a peptide; cholesterol; or other pharmaceutically acceptable leaving group which when administered in vivo is capable of providing a compound wherein Ru ils independently H or phosphate; (3) R6 is alkyl (including lower alkyl), alkenyl, alkynyl, Br- vinyl, hydroxy, O-alkyl, O-alkenyl, chloro, bromo, fluoro, iodo, N02, amino, lower alkylamino or di- (loweralkyl) amino; (4) R and R9 are independently OH or OR, wherein at least one of R and R9 is OR2 (and R2 is not hydrogen); (5) R is H, alkyl (including lower alkyl), chlorine, bromine, or iodine; and (6) X is O, S, SO2 or CH2.
In a third subembodiment, a compound of Formula XV, or its pharmaceutically acceptable salt or prodrug, is provided in which: (1) Base is a purine or pyrimidine base as defined herein; (2) R'is independently H; phosphate (including monophosphate, diphosphate, triphosphate, or a stabilized phosphate prodrug); acyl (including lower acyl) ; alkyl (including lower alkyl) ; sulfonate ester including alkyl or arylalkyl sulfonyl including methanesulfonyl and benzyl, wherein the phenyl group is optionally substituted with one or more substituents as described in the definition of aryl given herein; a lipid, including a phospholipid ; an amino acid; a carbohydrate; a peptide; cholesterol; or other pharmaceutically acceptable leaving group which when administered in vivo is capable of providing a compound wherein R'is independently H or phosphate; (3) R6 is alkyl (including lower alkyl), alkenyl, alkynyl, Br- vinyl, hydroxy, O-alkyl, O-alkenyl, chloro, bromo, fluoro, iodo, NO2, amino, lower alkylamino, or di (lower-alkyl) amino; (4) R7 and R9 are independently hydrogen, OR2, alkyl (including lower alkyl), alkenyl, alkynyl, Br-vinyl, 0-alkenyl, chlorine, bromine, iodine, NO2, amino, lower alkylamino, or di (loweralkyl) amino; wherein at least one of R7 and R9 is oR2 (and R2 is not hydrogen); (5) R8 is H; and (6) X is O, S, SO2 or CH2.
In a fourth subembodiment, a compound of Formula XV, or its pharmaceutically acceptable salt or prodrug, is provided in which: (1) Base is a purine or pyrimidine base as defined herein; (2) R'is independently H; phosphate (including monophosphate, diphosphate, triphosphate, or a stabilized phosphate prodrug); acyl (including lower acyl) ; alkyl (including lower alkyl) ; sulfonate ester including alkyl or arylalkyl sulfonyl including methanesulfonyl and benzyl, wherein the phenyl group is optionally substituted with one or more substituents as described in the definition of aryl given herein; a lipid, including a phospholipid; an amino acid; a carbohydrate; a peptide; cholesterol; or other pharmaceutically acceptable leaving group which when administered in vivo is capable of providing a compound wherein Ru ils independently H or phosphate; (3) R6 is alkyl (including lower alkyl), alkenyl, alkynyl, Br- vinyl, hydroxy, O-alkyl, 0-alkenyl, chloro, bromo, fluoro, iodo, NO2, amino, lower
alkylamino, or di (loweralkyl) amino; (4) R7 and R9 are independently hydrogen, oR2, alkyl (including lower alkyl), alkenyl, alkynyl, Br-vinyl, O-alkenyl, chlorine, bromine, iodine, NO2, amino, lower alkylamino, or di (loweralkyl) amino; wherein at least one of R7 and R9 is OR2 (and R2 is not hydrogen); (5) R is H, alkyl (including lower alkyl), chlorine, bromine, or iodine; and (6) X is O.
In a fifth subembodiment, a compound of Formula XV, or its pharmaceutically acceptable salt or prodrug, is provided in which: (1) Base is a purine or pyrimidine base as defined herein; (2) R'is independently H; phosphate (including monophosphate, diphosphate, triphosphate, or a stabilized phosphate prodrug); acyl (including lower acyl) ; alkyl (including lower alkyl) ; sulfonate ester including alkyl or arylalkyl sulfonyl including methanesulfonyl and benzyl, wherein the phenyl group is optionally substituted with one or more substituents as described in the definition of aryl given herein; a lipid, including a phospholipid ; an amino acid; a carbohydrate; a peptide; cholesterol; or other pharmaceutically acceptable leaving group which when administered in vivo is capable of providing a compound wherein R'is independently H or phosphate; (3) R6 is alkyl (including lower alkyl), alkenyl, alkynyl, Br- vinyl, hydroxy, O-alkyl, O-alkenyl, chloro, bromo, fluoro, iodo, NO2, amino, lower alkylamino, or di (loweralkyl) amino; (4) R7 and R9 are independently OH or OR2, wherein at least one of R7 and R9 is OR2 (and R2 is not hydrogen); (5) R8 is H; and (6) X is O, S, SO2, or CH2.
In a sixth subembodiment, a compound of Formula XV, or its pharmaceutically acceptable salt or prodrug, is provided in which: (1) Base is a purine or pyrimidine base as defined herein; (2) Rl is independently H; phosphate (including monophosphate, diphosphate, triphosphate, or a stabilized phosphate prodrug); acyl (including lower acyl) ; alkyl (including lower alkyl) ; sulfonate ester including alkyl or arylalkyl sulfonyl including methanesulfonyl and benzyl, wherein the phenyl group is optionally substituted with one or more substituents as described in the definition of aryl given herein; a lipid, including a phospholipid; an amino acid; a carbohydrate; a peptide; cholesterol; or other pharmaceutically acceptable leaving group which when administered in vivo is capable of providing a compound wherein Ru ils independently H or phosphate; (3) R6 is alkyl (including lower alkyl), alkenyl, alkynyl, Br- vinyl, hydroxy, O-alkyl, O-alkenyl, chloro, bromo, fluoro, iodo, NO2, amino, lower alkylamino, or di (loweralkyl) amino; (4) R7 and R9 are independently OH or OR2, wherein at least one of R7 and R9 is oR2 (and R2 is not hydrogen); (5) R8 is H, alkyl (including lower alkyl), chlorine, bromine, or iodine; and (6) X is O.
In a seventh subembodiment, a compound of Formula XV, or its pharmaceutically acceptable salt or prodrug, is provided in which: (1) Base is a purine or pyrimidine base as defined herein; (2) R'is independently H; phosphate (including monophosphate, diphosphate, triphosphate, or a stabilized phosphate prodrug); acyl (including lower acyl) ; alkyl (including lower alkyl) ; sulfonate ester including alkyl or arylalkyl sulfonyl including methanesulfonyl and benzyl, wherein the phenyl group is optionally substituted with one or more substituents as described in the definition of aryl given herein; a lipid, including a phospholipid ; an amino acid; a carbohydrate; a peptide; cholesterol; or other pharmaceutically acceptable leaving group which when administered in vivo is capable of providing a compound wherein R'is independently H or phosphate; (3) R6 is alkyl (including lower alkyl), alkenyl, alkynyl, Br- vinyl, hydroxy, O-alkyl, O-alkenyl, chloro, bromo, fluoro, iodo, NO2, amino, lower alkylamino, or di (loweralkyl) amino; (4) R7 and R9 are independently hydrogen, OR2, alkyl (including lower alkyl), alkenyl, alkynyl, Br-vinyl, O-alkenyl, chlorine, bromine, iodine, NO2, amino, lower alkylamino, or di (loweralkyl) amino; wherein at least one of R7 and R9 is OR2 (and R is not hydrogen); (5) R8 is H; and (6) X is O.
In an eighth subembodiment, a compound of Formula XV, or its pharmaceutically acceptable salt or prodrug, is provided in which: (1) Base is a purine or pyrimidine base as defined herein; (2) R'is independently H or phosphate; (3) R6 is alkyl (including lower alkyl), alkenyl, alkynyl, Br-vinyl, hydroxy, O-alkyl, O-alkenyl, chloro, bromo, fluoro, iodo, NO2, amino, lower alkylamino or di (loweralkyl) amino; (4) R7 and R9 are independently OH or OR2, wherein at least one of R7 and R9 is OR2 (and R2 is not hydrogen) ; (5) R8 is H; and (6) X is O, S, SO2 or CH2.
In a ninth subembodiment, a compound of Formula XV, or its pharmaceutically acceptable salt or prodrug, is provided in which: (1) Base is a purine or pyrimidine base as defined herein; (2) Rl is independently H or phosphate; (3) R6 is alkyl ; (4) R7 and R9 are independently OH or OR, wherein at least one of R and R9 is OR2 (and R2 is not hydrogen); (5) R8 is H; and (6) X is O, S, SO2, or CH2.
In a tenth preferred subembodiment, a compound of Formula XV, or its pharmaceutically acceptable salt or prodrug, is provided in which: (1) Base is a purine or pyrimidine base as defined herein; (2) R'is independently H or phosphate; (3) R6 is alkyl ; (4) R7 and R9 are independently OH or oR2, wherein at least one of R7 and R9 is OR2 (and R2 is not hydrogen); (5) R8 is H; and (6) X is O.
In even more preferred subembodiments, a compound of Formula XV, or its pharmaceutically acceptable salt or prodrug, is provided in which: (1) Base is adenine; (2) R'is hydrogen; (3) R6 is methyl ; (4) R7 is hydroxyl (5) R9 is L-valinyl ; (6) R8 is hydrogen; and (7) X is O ; (1) Base is guanine; (2) R'is hydrogen; (3) R6 is methyl ; (4) R7 is hydroxyl (5) R9 is L-valinyl ; (6) R8 is hydrogen; and (7) X is O ; (1) Base is cytosine; (2) R'is hydrogen; (3) R6 is methyl ; (4) R7 is hydroxyl (5) R9 is L-valinyl ; (6) R8 is hydrogen; and (7) X is O ; (1) Base is thymidine; (2) R'is hydrogen; (3) R6 is methyl ; (4) R7 is hydroxyl (5) R9 is L-valinyl ; (6) R8 is hydrogen; and (7) X is O ; (1) Base is uracil ; (2) R'is hydrogen; (3) R6 is methyl ; (4) R7 is hydroxyl (5) R9 is L- valinyl ; (6) R8 is hydrogen; and (7) X is O ; (1) Base is adenine; (2) R'is phosphate; (3) R6 is methyl ; (4) R7 is hydroxyl (5) R9 is L-valinyl ; (6) R8 is hydrogen; and (7) X is O ; (1) Base is adenine; (2) R'is hydrogen; (3) R6 is ethyl ; (4) R7 is hydroxyl (5) R9 is L- valinyl ; (6) R8 is hydrogen; and (7) X is O ; (1) Base is adenine; (2) R'is hydrogen; (3) R6 is propyl ; (4) R7 is hydroxyl (5) R9 is L-valinyl ; (6) R8 is hydrogen; and (7) X is O ; (1) Base is adenine; (2) R'is hydrogen; (3) R6 is butyl ; (4) R7 is hydroxyl (5) R9 is L- valinyl ; (6) R8 is hydrogen; and (7) X is O ; (1) Base is adenine; (2) R'is hydrogen; (3) R6 is methyl ; (4) R7 is hydroxyl (5) R9 is L-valinyl ; (6) R8 is hydrogen; and (7) X is S; (1) Base is adenine; (2) R'is hydrogen; (3) R6 is methyl ; (4) R7 is hydroxyl (5) R9 is L-valinyl ; (6) R8 is hydrogen; and (7) X is SO2 ; or (1) Base is adenine; (2) R'is hydrogen; (3) R6 is methyl ; (4) R7 is hydroxyl (5) R9 is L-valinyl ; (6) R8 is hydrogen; and (7) X is CH2.
In a thirteenth principal embodiment, a compound of Formula XVI, or a pharmaceutically acceptable salt or prodrug thereof, is provided:
wherein: R', R2 and R3 are independently H, phosphate (including mono-, di-or triphosphate and a stabilized phosphate); straight chained, branched or cyclic alkyl (including lower alkyl) ; acyl (including lower acyl) ; CO-alkyl, CO-aryl, CO-alkoxyalkyl, CO-aryloxyalkyl, CO- substituted aryl, sulfonate ester including alkyl or arylalkyl sulfonyl including methanesulfonyl and benzyl, wherein the phenyl group is optionally substituted with one or more substituents as described in the definition of aryl given herein; alkylsulfonyl, arylsulfonyl, aralkylsulfonyl, a lipid, including a phospholipid; an amino acid; and amino acid residue, a carbohydrate; a peptide; cholesterol; or other pharmaceutically acceptable leaving group which when administered in vivo is capable of providing a compound wherein R', R2 and/or R3 is independently H or phosphate; wherein at least one of R2 and R3 is not hydrogen; Y is hydrogen, bromo, chloro, fluoro, iodo, OH, OR4, NH, NHR5, NR4R5, SH and SR4 ; X'and x2 are independently selected from the group consisting of H, straight chained, branched or cyclic alkyl, CO-alkyl, CO-aryl, CO-alkoxyalkyl, chloro, bromo, fluoro, iodo, OH, OR4, NH, NHR5, NR4R5, SH and SR4 ; and R4 and R5 are independently hydrogen, acyl (including lower acyl), or alkyl (including but not limited to methyl, ethyl, propyl and cyclopropyl).
In a preferred subembodiment, a compound of Formula XVI, or a pharmaceutically acceptable salt or prodrug thereof, is provided wherein: R'is H or phosphate (preferably H);
R and R3 are independently H, phosphate, acyl or an amino acid residue, wherein at least one of R2 and R3 is acyl or an amino acid residue; Xt is H ; X2 is H or NH2; and Y is hydrogen, bromo, chloro, fluoro, iodo, NH2 or OH.
In a fourteenth principal embodiment, a compound of Formula XVII, or a pharmaceutically acceptable salt or prodrug thereof, is provided: wherein: R', R and R3 are independently H, phosphate (including mono-, di-or triphosphate and a stabilized phosphate); straight chained, branched or cyclic alkyl (including lower alkyl) ; acyl (including lower acyl) ; CO-alkyl, CO-aryl, CO-alkoxyalkyl, CO-aryloxyalkyl, CO- substituted aryl, sulfonate ester including alkyl or arylalkyl sulfonyl including methanesulfonyl and benzyl, wherein the phenyl group is optionally substituted with one or more substituents as described in the definition of aryl given herein; alkylsulfonyl, arylsulfonyl, aralkylsulfonyl, a lipid, including a phospholipid ; an amino acid; and amino acid residue, a carbohydrate; a peptide; cholesterol; or other pharmaceutically acceptable leaving group which when administered in vivo is capable of providing a compound wherein R', R2 and/or R3 is independently H or phosphate; wherein at least one of R2 and R3 is not hydrogen; Y is hydrogen, bromo, chloro, fluoro, iodo, OR4, NR4R5 or SR4 ; Xl is selected from the group consisting of H, straight chained, branched or cyclic alkyl, CO- alkyl, CO-aryl, CO-alkoxyalkyl, chloro, bromo, fluoro, iodo, oR4 NR4NR5 or SR5 ; and
R4 and R5 are independently hydrogen, acyl (including lower acyl), or alkyl (including but not limited to methyl, ethyl, propyl and cyclopropyl).
In a preferred subembodiment, a compound of Formula XVII, or a pharmaceutically acceptable salt or prodrug thereof, is provided wherein: R'is H or phosphate (preferably H); R and R3 are independently H, phosphate, acyl or an amino acid residue, wherein at least one of R2 and R3 is acyl or an amino acid residue; Xl is H or CH3; and Y is hydrogen, bromo, chloro, fluoro, iodo, NH2 or OH.
In a fifteenth principal embodiment, a compound selected from Formulas XVIII and XIX, or a pharmaceutically acceptable salt or prodrug thereof, is provided: wherein: Base is a purine or pyrimidine base as defined herein; R', R2 and R3 are independently H, phosphate (including mono-, di-or triphosphate and a stabilized phosphate); straight chained, branched or cyclic alkyl (including lower alkyl) ; acyl (including lower acyl) ; CO-alkyl, CO-aryl, CO-alkoxyalkyl, CO-aryloxyalkyl, CO- substituted aryl, sulfonate ester including alkyl or arylalkyl sulfonyl including methanesulfonyl and benzyl, wherein the phenyl group is optionally substituted with one or more substituents as described in the definition of aryl given herein; alkylsulfonyl, arylsulfonyl, aralkylsulfonyl, a lipid, including a phospholipid ; an amino acid; and amino acid residue, a carbohydrate; a peptide; cholesterol; or other pharmaceutically acceptable leaving group which when administered in vivo is capable of providing a compound wherein R', W and/or R3 is independently H or phosphate; wherein R2 is not hydrogen;
R6 is alkyl (including lower alkyl and halogenated alkyl), CH3, CF3, azido, cyano, alkenyl, <BR> <BR> <BR> alkynyl, Br-vinyl, 2-Br-ethyl,-C (O) O (alkyl),-C (O) O (lower alkyl),-O (acyl),-O (lower acyl), -O (alkyl),-O (lower alkyl),-O (alkenyl), CF3, chloro, bromo, fluoro, iodo, NO2, NH2,- NH (lower alkyl),-NH (acyl),-N (lower alkyl) 2, -N (acyl) 2; and X is 0, S, SO2 or CH2.
In a first subembodiment, a compound of Formula XVIII and XIX, or a pharmaceutically acceptable salt or prodrug thereof, is provided wherein: Base is a purine or pyrimidine base as defined herein; R'is H or phosphate (preferably H); R2 and R3 are independently H, phosphate, acyl or an amino acid residue, wherein at least one of R2 and R3 is acyl or an amino acid residue; R6 is alkyl ; and X is O, S, SO2 or CH2.
In a second subembodiment, a compound of Formula XVIII and XIX, or a pharmaceutically acceptable salt or prodrug thereof, is provided wherein: Base is a purine or pyrimidine base as defined herein; R'is H or phosphate (preferably H); R2 and R3 are independently H, phosphate, acyl or an amino acid residue, wherein at least one of R2 and R3 is an amino acid residue; R6 is alkyl ; and X is O, S, SO2 or CH2.
In a third subembodiment, a compound of Formula XVIII and XIX, or a pharmaceutically acceptable salt or prodrug thereof, is provided wherein: Base is a purine or pyrimidine base as defined herein; R1 is H or phosphate (preferably H); R2 and R3 are independently H, phosphate, acyl or an amino acid residue, wherein at least one of R2 and R3 is acyl or an amino acid residue; R6 is alkyl ; and XisO.
In a sixteenth principal embodiment the invention provides a compound of Formula XX, or a pharmaceutically acceptable salt or prodrug thereof :
wherein: Base is a purine or pyrimidine base as defined herein; R'is H, phosphate (including mono-, di-or triphosphate and a stabilized phosphate); straight chained, branched or cyclic alkyl (including lower alkyl) ; acyl (including lower acyl) ; CO- alkyl, CO-aryl, CO-alkoxyalkyl, CO-aryloxyalkyl, CO-substituted aryl, sulfonate ester including alkyl or arylalkyl sulfonyl including methanesulfonyl and benzyl, wherein the phenyl group is optionally substituted with one or more substituents as described in the definition of aryl given herein; alkylsulfonyl, arylsulfonyl, aralkylsulfonyl, a lipid, including a phospholipid ; an amino acid; and amino acid residue, a carbohydrate; a peptide; cholesterol; or other pharmaceutically acceptable leaving group which when administered in vivo is capable of providing a compound wherein R'is H or phosphate; R6 is alkyl (including lower alkyl), azido, cyano, alkenyl, alkynyl, Br-vinyl, 2-Br-ethyl, -C(O)O(alkyl), -C(O)O(lower alkyl), -O(acyl), -O(lower acyl), -O(alkyl), -O(lower alkyl), -O (alkenyl), CF3, chloro, bromo, fluoro, iodo, NO2, NH2,-NH (lower alkyl),-NH (acyl), -N (lower alkyl) 2, -N (acyl) 2; R7 and R9 are independently hydrogen, OR2, hydroxy, alkyl (including lower alkyl), azido, cyano, alkenyl, alkynyl, Br-vinyl,-C (O) O (alkyl),-C (O) O (lower alkyl),-O (acyl),-O (lower acyl),-O (alkyl),-O (lower alkyl),-O (alkenyl), chlorine, bromine, iodine, NO2, NH2, -NH (lower alkyl),-NH (acyl),-N (lower alkyl) 2,-N (acyl) 2; wherein at least one of R7 and R9 is OR2, wherein each R2 is independently phosphate (including mono-, di-or triphosphate and a stabilized phosphate); straight chained, branched or cyclic alkyl (including lower alkyl) ; acyl (including lower acyl) ; CO-alkyl, CO-aryl, CO-
alkoxyalkyl, CO-aryloxyalkyl, CO-substituted aryl, sulfonate ester including alkyl or arylalkyl sulfonyl including methanesulfonyl and benzyl, wherein the phenyl group is optionally substituted with one or more substituents as described in the definition of aryl given herein; alkylsulfonyl, arylsulfonyl, aralkylsulfonyl, a lipid, including a phospholipid; an amino acid; and amino acid residue, a carbohydrate; a peptide; cholesterol; or other pharmaceutically acceptable leaving group which when administered in vivo is capable of providing a compound wherein R is H or phosphate; R and Rl° are independently H, alkyl (including lower alkyl), chlorine, bromine or iodine; alternatively, R7 and Rl°, R8 and R9, or R8 and Rl° can come together to form a pi bond; and X is O, S, SO2 or CH2.
In a first subembodiment, a compound of Formula XX, or its pharmaceutically acceptable salt or prodrug, is provided in which: (1) Base is a purine or pyrimidine base as defined herein; (2) R'is independently H or phosphate (including monophosphate, diphosphate, triphosphate, or a stabilized phosphate prodrug); acyl (including lower acyl) ; alkyl (including lower alkyl) ; sulfonate ester including alkyl or arylalkyl sulfonyl including methanesulfonyl and benzyl, wherein the phenyl group is optionally substituted with one or more substituents as described in the definition of aryl given herein; a lipid, including a phospholipid; an amino acid; a carbohydrate; a peptide; cholesterol; or other pharmaceutically acceptable leaving group which when administered in vivo is capable of providing a compound wherein R'is independently H or phosphate; (3) R6 is alkyl ; (4) R7 and R9 are independently OR2, alkyl, alkenyl, alkynyl, Br-vinyl, 0-alkenyl, chlorine, bromine, iodine, NO2, amino, lower alkylamino or di (loweralkyl) amino; wherein at least one of R7 and R9 is OR2 (and R2 is not hydrogen); (5) R8 and Rl° are independently H, alkyl (including lower alkyl), chlorine, bromine, or iodine; and (6) X is O, S, SO2 or CH2.
In a second subembodiment, a compound of Formula XX, or its pharmaceutically acceptable salt or prodrug, is provided in which: (1) Base is a purine or pyrimidine base as defined herein; (2) R'is independently H or phosphate (including monophosphate, diphosphate, triphosphate, or a stabilized phosphate prodrug); acyl (including lower acyl) ; alkyl (including lower alkyl) ; sulfonate ester including alkyl or arylalkyl sulfonyl including methanesulfonyl and benzyl, wherein the phenyl group is optionally substituted with one or more substituents as described in the definition of aryl given herein; a lipid, including a phospholipid; an amino acid; a carbohydrate; a peptide; cholesterol; or other
pharmaceutically acceptable leaving group which when administered in vivo is capable of providing a compound wherein R'is independently H or phosphate; (3) R6 is alkyl, alkenyl, alkynyl, Br-vinyl, hydroxy, O-alkyl, 0-alkenyl, chloro, bromo, fluoro, iodo, NO2, amino, lower alkylamino, or di (loweralkyl) amino; (4) R7 and R9 are independently OH or OR2, wherein at least one of R and R9 is oR2 (and R2 is not hydrogen); (5) R8 and Rl° are independently H, alkyl (including lower alkyl), chlorine, bromine, or iodine; and (6) X is O, S, SO2 or CH2.
In a third subembodiment, a compound of Formula XX, or its pharmaceutically acceptable salt or prodrug, is provided in which: (1) Base is a purine or pyrimidine base as defined herein; (2) R'is independently H or phosphate (including monophosphate, diphosphate, triphosphate, or a stabilized phosphate prodrug); acyl (including lower acyl) ; alkyl (including lower alkyl) ; sulfonate ester including alkyl or arylalkyl sulfonyl including methanesulfonyl and benzyl, wherein the phenyl group is optionally substituted with one or more substituents as described in the definition of aryl given herein; a lipid, including a phospholipid; an amino acid; a carbohydrate; a peptide; cholesterol; or other pharmaceutically acceptable leaving group which when administered in vivo is capable of providing a compound wherein R1 is independently H or phosphate; (3) R6 is alkyl, alkenyl, alkynyl, Br-vinyl, hydroxy, O-alkyl, 0-alkenyl, chloro, bromo, fluoro, iodo, NOz, amino, lower alkylamino or di (loweralkyl) amino; (4) R and R9 are independently OR2, alkyl, alkenyl, alkynyl, Br-vinyl, O-alkenyl, chlorine, bromine, iodine, NO2, amino, lower alkylamino or di (loweralkyl) amino; wherein at least one of R7 and R9 is OR2 (and R2 is not hydrogen); (5) R8 and Rl° are H; and (6) X is O, S, S02 or CH2.
In a fourth subembodiment, a compound of Formula XX, or its pharmaceutically acceptable salt or prodrug, is provided in which: (1) Base is a purine or pyrimidine base as defined herein; (2) R'is independently H or phosphate (including monophosphate, diphosphate, triphosphate, or a stabilized phosphate prodrug); acyl (including lower acyl) ; alkyl (including lower alkyl) ; sulfonate ester including alkyl or arylalkyl sulfonyl including methanesulfonyl and benzyl, wherein the phenyl group is optionally substituted with one or more substituents as described in the definition of aryl given herein; a lipid, including a phospholipid ; an amino acid; a carbohydrate; a peptide; cholesterol; or other pharmaceutically acceptable leaving group which when administered in vivo is capable of providing a compound wherein R1 is independently H or phosphate; (3) R6 is alkyl, alkenyl, alkynyl, Br-vinyl, hydroxy, O-alkyl, 0-alkenyl, chloro, bromo, fluoro, iodo, NO2, amino,
lower alkylamino, or di (loweralkyl) amino; (4) R7 and R9 are independently oR2, alkyl, alkenyl, alkynyl, Br-vinyl, 0-alkenyl, chlorine, bromine, iodine, NO2, amino, lower alkylamino, or di (loweralkyl) amino; wherein at least one of R7 and R9 is OR2 (and R2 is not hydrogen); (5) R8 and Rl° are independently H, alkyl (including lower alkyl), chlorine, bromine, or iodine; and (6) X is O.
In a fifth subembodiment, a compound of Formula XX, or its pharmaceutically acceptable salt or prodrug, is provided in which: (1) Base is a purine or pyrimidine base as defined herein; (2) R'is independently H or phosphate (including monophosphate, diphosphate, triphosphate, or a stabilized phosphate prodrug); acyl (including lower acyl) ; alkyl (including lower alkyl) ; sulfonate ester including alkyl or arylalkyl sulfonyl including methanesulfonyl and benzyl, wherein the phenyl group is optionally substituted with one or more substituents as described in the definition of aryl given herein; a lipid, including a phospholipid; an amino acid; a carbohydrate; a peptide; cholesterol ; or other pharmaceutically acceptable leaving group which when administered in vivo is capable of providing a compound wherein R'is independently H or phosphate; (3) R6 is alkyl ; (4) R7 and R9 are independently OH or OR2, wherein at least one of R7 and R9 is OR2 (and W is not hydrogen); (5) R8 and R10 are independently H, alkyl (including lower alkyl), chlorine, bromine or iodine; and (6) X is O, S, S02 or CH2.
In a sixth subembodiment, a compound of Formula XX, or its pharmaceutically acceptable salt or prodrug, is provided in which: (1) Base is a purine or pyrimidine base as defined herein; (2) R'is independently H or phosphate (including monophosphate, diphosphate, triphosphate, or a stabilized phosphate prodrug); acyl (including lower acyl) ; alkyl (including lower alkyl) ; sulfonate ester including alkyl or arylalkyl sulfonyl including methanesulfonyl and benzyl, wherein the phenyl group is optionally substituted with one or more substituents as described in the definition of aryl given herein; a lipid, including a phospholipid; an amino acid; a carbohydrate; a peptide; cholesterol; or other pharmaceutically acceptable leaving group which when administered in vivo is capable of providing a compound wherein R'is independently H or phosphate; (3) R6 is alkyl ; (4) R7 and R9 are independently OR2, alkyl (including lower alkyl), alkenyl, alkynyl, Br-vinyl, O- alkenyl, chlorine, bromine, iodine, NO2, amino, lower alkylamino, or di (loweralkyl) amino; wherein at least one of R7 and R9 is OR2 (and R2 is not hydrogen); (5) R and RIO are H; and (6) X is O, S, SO2, or CH2.
In a seventh subembodiment, a compound of Formula XX, or its pharmaceutically acceptable salt or prodrug, is provided in which: (1) Base is a purine or pyrimidine base as defined herein; (2) R'is independently H or phosphate (including monophosphate, diphosphate, triphosphate, or a stabilized phosphate prodrug); acyl (including lower acyl) ; alkyl (including lower alkyl) ; sulfonate ester including alkyl or arylalkyl sulfonyl including methanesulfonyl and benzyl, wherein the phenyl group is optionally substituted with one or more substituents as described in the definition of aryl given herein; a lipid, including a phospholipid; an amino acid; a carbohydrate; a peptide; cholesterol; or other pharmaceutically acceptable leaving group which when administered in vivo is capable of providing a compound wherein R'is independently H or phosphate; (3) R6 is alkyl ; (4) R7 and R9 are independently oR2, alkyl (including lower alkyl), alkenyl, alkynyl, Br-vinyl, O- alkenyl, chlorine, bromine, iodine, NO2, amino, lower alkylamino or di (loweralkyl) amino; wherein at least one of R7 and R9 is oR2 (and R2 is not hydrogen); (5) R8 and RIO are independently H, alkyl (including lower alkyl), chlorine, bromine or iodine; and (6) X is O.
In a eighth subembodiment, a compound of Formula XX, or its pharmaceutically acceptable salt or prodrug, is provided in which: (1) Base is a purine or pyrimidine base as defined herein; (2) R'is independently H or phosphate (including monophosphate, diphosphate, triphosphate, or a stabilized phosphate prodrug); acyl (including lower acyl) ; alkyl (including lower alkyl) ; sulfonate ester including alkyl or arylalkyl sulfonyl including methanesulfonyl and benzyl, wherein the phenyl group is optionally substituted with one or more substituents as described in the definition of aryl given herein; a lipid, including a phospholipid; an amino acid; a carbohydrate; a peptide; cholesterol; or other pharmaceutically acceptable leaving group which when administered in vivo is capable of providing a compound wherein R'is independently H or phosphate; (3) R6 is alkyl (including lower alkyl), alkenyl, alkynyl, Br-vinyl, hydroxy, O-alkyl, 0-alkenyl, chloro, bromo, fluoro, iodo, NO2, amino, lower alkylamino or di (loweralkyl) amino; (4) R 7and R9 are independently OH or OR2, wherein at least one of R'and R9 is OR2 (and R2 is not hydrogen); (5) R8 and RIO are hydrogen; and (6) X is O, S, SO2 or CH2.
In a ninth subembodiment, a compound of Formula XX, or its pharmaceutically acceptable salt or prodrug, is provided in which: (1) Base is a purine or pyrimidine base as defined herein; (2) R'is independently H or phosphate (including monophosphate, diphosphate, triphosphate, or a stabilized phosphate prodrug); acyl (including lower acyl) ; alkyl (including lower alkyl) ; sulfonate ester including alkyl or arylalkyl sulfonyl including
methanesulfonyl and benzyl, wherein the phenyl group is optionally substituted with one or more substituents as described in the definition of aryl given herein; a lipid, including a phospholipid; an amino acid; a carbohydrate; a peptide; cholesterol; or other pharmaceutically acceptable leaving group which when administered in vivo is capable of providing a compound wherein R'is independently H or phosphate; (3) R6 is alkyl (including lower alkyl), alkenyl, alkynyl, Br-vinyl, hydroxy, O-alkyl, O-alkenyl, chloro, bromo, fluoro, iodo, NO2, amino, lower alkylamino or di (loweralkyl) amino; (4) R7 and R9 are independently OH or OR2, wherein at least one of R7 and R9 is oR2 (and R is not hydrogen); (5) R8 and R'° are independently H, alkyl (including lower alkyl), chlorine, bromine or iodine; and (6) X is 0.
In a tenth preferred subembodiment, a compound of Formula XX, or its pharmaceutically acceptable salt or prodrug, is provided in which: (1) Base is a purine or pyrimidine base as defined herein; (2) R'is independently H or phosphate (including monophosphate, diphosphate, triphosphate, or a stabilized phosphate prodrug); acyl (including lower acyl) ; alkyl (including lower alkyl) ; sulfonate ester including alkyl or arylalkyl sulfonyl including methanesulfonyl and benzyl, wherein the phenyl group is optionally substituted with one or more substituents as described in the definition of aryl given herein; a lipid, including a phospholipid ; an amino acid; a carbohydrate; a peptide; cholesterol ; or other pharmaceutically acceptable leaving group which when administered in vivo is capable of providing a compound wherein R'is independently H or phosphate; (3) R6 is alkyl (including lower alkyl), alkenyl, alkynyl, Br-vinyl, hydroxy, O-alkyl, 0-alkenyl, chloro, bromo, fluoro, iodo, NO2, amino, lower alkylamino or di (loweralkyl) amino; (4) R7 and R9 are independently OR2, alkyl (including lower alkyl), alkenyl, alkynyl, Br-vinyl, O- alkenyl, chlorine, bromine, iodine, NO2, amino, lower alkylamino, or di (loweralkyl) amino; wherein at least one of R7 and R9 is OR2 (and R2 is not hydrogen); (5) R8 and Rio are hydrogen; and (6) X is O.
In an eleventh subembodiment, a compound of Formula XX, or its pharmaceutically acceptable salt or prodrug, is provided in which: (1) Base is a purine or pyrimidine base as defined herein; (2) R'is independently H or phosphate; (3) R6 is alkyl (including lower alkyl), alkenyl, alkynyl, Br-vinyl, hydroxy, O-alkyl, 0-alkenyl, chloro, bromo, fluoro, iodo, NO2, amino, lower alkylamino or di (loweralkyl) amino; (4) R7 and R9 are independently OH or OR2, wherein at least one of R7 and R9 is OR2 (and R is not hydrogen); (5) R8 and RIO are hydrogen; and (6) X is O, S, SO2 or CH2.
In a twelfth subembo, ent, a compound of Formula XX, or its pharmaceutically acceptable salt or prodrug, is provided in which: (1) Base is a purine or pyrimidine base as defined herein; (2) R'is independently H or phosphate; (3) R6 is alkyl ; (4) R 7and R9 are independently OH or OR2, wherein at least one of R 7and R9 is OR2 (and R2 is not hydrogen); (5) R8 and Rl° are hydrogen; and (6) X is O, S, SO2, or CH2.
In a thirteenth subembodiment, a compound of Formula XX, or its pharmaceutically acceptable salt or prodrug, is provided in which: (1) Base is a purine or pyrimidine base as defined herein; (2) R'is independently H or phosphate; (3) R6 is alkyl ; (4) R 7and R9 are independently OH or OR2, wherein at least one of R 7and R9 is OR2 (and R2 is not hydrogen); (5) R8 and R10 are independently H, alkyl (including lower alkyl), chlorine, bromine, or iodine; and (6) X is O.
In a fourteenth subembodiment, a compound of Formula XX, or its pharmaceutically acceptable salt or prodrug, is provided in which: (1) Base is a purine or pyrimidine base as defined herein; (2) R'is independently H or phosphate; (3) R6 is alkyl ; (4) R7 and R9 are independently OR 2, alkyl (including lower alkyl), alkenyl, alkynyl, Br-vinyl, 0-alkenyl, chlorine, bromine, iodine, NO2, amino, lower alkylamino or di (loweralkyl) amino; wherein at least one of R7 and R9 is OR2 (and R2 is not hydrogen); (5) R8 and RIO are hydrogen; and (6) XisO.
In even more preferred subembodiments, a compound of Formula XX, or its pharmaceutically acceptable salt or prodrug, is provided in which: (1) Base is adenine; (2) R'is hydrogen; (3) R6 is methyl; (4) R7 is hydroxyl (5) R9 is L-valinyl ; (6) R8 and R'° are hydrogen; and (7) X is O ; (1) Base is guanine; (2) R'is hydrogen; (3) R6 is methyl ; (4) R7 is hydroxyl (5) R9 is L-valinyl ; (6) R8 and Rl° are hydrogen; and (7) X is O ; (1) Base is cytosine; (2) R'is hydrogen; (3) R6 is methyl ; (4) R7 is hydroxyl (5) R9 is L-valinyl ; (6) R8 and R10 are hydrogen; and (7) X is O ; (1) Base is thymidine; (2) R'is hydrogen; (3) R6 is methyl ; (4) R7 is hydroxyl (5) R9 is L-valinyl ; (6) R8 and Rl° are hydrogen; and (7) X is O ; (1) Base is uracil ; (2) R'is hydrogen; (3) R6 is methyl; (4) R7 is hydroxyl (5) R9 is L- valinyl ; (6) R8 and Rl° are hydrogen; and (7) X is O ;
(1) Base is adenine; (2) R'is phosphate; (3) R6 is methyl; (4) R7 is hydroxyl (5) R9 is L-valinyl ; (6) R8 and Rl° are hydrogen; and (7) X is O ; (1) Base is adenine; (2) R'is hydrogen; (3) R6 is ethyl ; (4) R7 is hydroxyl (5) R9 is L- valinyl ; (6) R8 and Rl° are hydrogen; and (7) X is O ; (1) Base is adenine; (2) Rl is hydrogen; (3) R6 is propyl ; (4) R7 is hydroxyl (5) R9 is L-valinyl ; (6) R8 and Rl° are hydrogen; and (7) X is O ; (1) Base is adenine; (2) R'is hydrogen; (3) R6 is butyl; (4) R7 is hydroxyl (5) R9 is L- valinyl ; (6) R8 and Rl° are hydrogen; and (7) X is O ; (1) Base is adenine; (2) Rl is hydrogen; (3) R6 is methyl ; (4) R7 is hydrogen (5) R9 is L-valinyl ; (6) R8 and Rl° are hydrogen; and (7) X is O ; (1) Base is adenine; (2) R'is hydrogen; (3) R6 is methyl; (4) R 7is hydroxyl (5) R9 is L-valinyl ; (6) R8 and R'° are hydrogen; and (7) X is S; (1) Base is adenine; (2) R'is hydrogen; (3) R6 is methyl; (4) R7 is hydroxyl (5) R9 is L-valinyl ; (6) R8 and Rl° are hydrogen; and (7) X is SO2 ; (1) Base is adenine; (2) R'is hydrogen; (3) R6 is methyl ; (4) R7 is hydroxyl (5) R9 is L-valinyl ; (6) R8 and Rl° are hydrogen; and (7) X is CH2.
Stereochemistry It is appreciated that nucleosides of the present invention have several chiral centers and may exist in and be isolated in optically active and racemic forms. Some compounds may exhibit polymorphism. It is to be understood that the present invention encompasses any racemic, optically-active, diastereomeric, polymorphic, or stereoisomeric form, or mixtures thereof, of a compound of the invention, which possess the useful properties described herein.
It being well known in the art how to prepare optically active forms (for example, by resolution of the racemic form by recrystallization techniques, by synthesis from optically- active starting materials, by chiral synthesis, or by chromatographic separation using a chiral stationary phase).
In particular, since the 1'and 4'carbons of the nucleoside are chiral, their nonhydrogen substituents (the base and the CHOR groups, respectively) can be either cis (on the same side) or trans (on opposite sides) with respect to the sugar ring system. The four
optical isomers therefore are represented by the following configurations (when orienting the sugar moiety in a horizontal plane such that the oxygen atom is in the back): cis (with both groups"up", which corresponds to the configuration of naturally occurring B-D nucleosides), cis (with both groups"down", which is a nonnaturally occurring B-L configuration), trans (with the C2'substituent"up"and the C4'substituent"down"), and trans (with the C2' substituent"down"and the C4'substituent"up"). The"D-nucleosides"are cis nucleosides in a natural configuration and the"L-nucleosides"are cis nucleosides in the non-naturally occurring configuration.
Likewise, most amino acids are chiral (designated as L or D, wherein the L enantiomer is the naturally occurring configuration) and can exist as separate enantiomers.
Examples of methods to obtain optically active materials are known in the art, and include at least the following. i) physical separation of crystals-a technique whereby macroscopic crystals of the individual enantiomers are manually separated. This technique can be used if crystals of the separate enantiomers exist, i. e., the material is a conglomerate, and the crystals are visually distinct; ii) simultaneous crystallization-a technique whereby the individual enantiomers are separately crystallized from a solution of the racemate, possible only if the latter is a conglomerate in the solid state; iii) enzymatic resolutions-a technique whereby partial or complete separation of a racemate by virtue of differing rates of reaction for the enantiomers with an enzyme; iv) enzymatic asymmetric synthesis-a synthetic technique whereby at least one step of the synthesis uses an enzymatic reaction to obtain an enantiomerically pure or enriched synthetic precursor of the desired enantiomer; v) chemical asymmetric synthesis-a synthetic technique whereby the desired enantiomer is synthesized from an achiral precursor under conditions that produce asymmetry (i. e. , chirality) in the product, which may be achieved using chiral catalysts or chiral auxiliaries;
vi) diastereomer separations-a technique whereby a racemic compound is reacted with an enantiomerically pure reagent (the chiral auxiliary) that converts the individual enantiomers to diastereomers. The resulting diastereomers are then separated by chromatography or crystallization by virtue of their now more distinct structural differences and the chiral auxiliary later removed to obtain the desired enantiomer; vii) first-and second-order asymmetric transformations-a technique whereby diastereomers from the racemate equilibrate to yield a preponderance in solution of the diastereomer from the desired enantiomer or where preferential crystallization of the diastereomer from the desired enantiomer perturbs the equilibrium such that eventually in principle all the material is converted to the crystalline diastereomer from the desired enantiomer. The desired enantiomer is then released from the diastereomer; viii) kinetic resolutions-this technique refers to the achievement of partial or complete resolution of a racemate (or of a further resolution of a partially resolved compound) by virtue of unequal reaction rates of the enantiomers with a chiral, non-racemic reagent or catalyst under kinetic conditions; ix) enantiospecific synthesis from non-racemic precursors-a synthetic technique whereby the desired enantiomer is obtained from non-chiral starting materials and where the stereochemical integrity is not or is only minimally compromised over the course of the synthesis; x) chiral liquid chromatography-a technique whereby the enantiomers of a racemate are separated in a liquid mobile phase by virtue of their differing interactions with a stationary phase. The stationary phase can be made of chiral material or the mobile phase can contain an additional chiral material to provoke the differing interactions; xi) chiral gas chromatography-a technique whereby the racemate is volatilized and enantiomers are separated by virtue of their differing interactions in the gaseous mobile phase with a column containing a fixed non-racemic chiral adsorbent phase;
xii) extraction with chiral solvents-a technique whereby the enantiomers are separated by virtue of preferential dissolution of one enantiomer into a particular chiral solvent ; xiii) transport across chiral membranes-a technique whereby a racemate is placed in contact with a thin membrane barrier. The barrier typically separates two miscible fluids, one containing the racemate, and a driving force such as concentration or pressure differential causes preferential transport across the membrane barrier. Separation occurs as a result of the non-racemic chiral nature of the membrane which allows only one enantiomer of the racemate to pass through.
II. Definitions The term"alkyl", as used herein, unless otherwise specified, refers to a saturated straight, branched, or cyclic, primary, secondary, or tertiary hydrocarbon of typically C, to Cl0, and specifically includes methyl, CF3, CC13, CFC12, CF2CI, ethyl, CH2CF3, CF2CF3, propyl, isopropyl, cyclopropyl, butyl, isobutyl, secbutyl, t-butyl, pentyl, cyclopentyl, isopentyl, neopentyl, hexyl, isohexyl, cyclohexyl, cyclohexylmethyl, 3-methylpentyl, 2,2- dimethylbutyl, and 2,3-dimethylbutyl. The term includes both substituted and unsubstituted alkyl groups, and particularly includes halogenated alkyl groups, and even more particularly fluorinated alkyl groups. Non-limiting examples of moieties with which the alkyl group can be substituted are selected from the group consisting of halogen (fluoro, chloro, bromo or iodo), hydroxyl, amino, alkylamino, arylamino, alkoxy, aryloxy, nitro, cyano, sulfonic acid, sulfate, phosphonic acid, phosphate, or phosphonate, either unprotected, or protected as necessary, as known to those skilled in the art, for example, as taught in Greene, et al., Protective Groups in Organic Synthesis, John Wiley and Sons, Second Edition, 1991, hereby incorporated by reference.
The term"lower alkyl", as used herein, and unless otherwise specified, refers to a C, to C4 saturated straight, branched, or if appropriate, a cyclic (for example, cyclopropyl) alkyl group, including both substituted and unsubstituted moieties.
The term"alkylamino"or"arylamino"refers to an amino group that has one or two alkyl or aryl substituents, respectively. Unless otherwise specifically stated in this
application, when alkyl is a suitable moiety, lower alkyl is preferred. Similarly, when alkyl or lower alkyl is a suitable moiety, unsubstituted alkyl or lower alkyl is preferred.
The term"protected"as used herein and unless otherwise defined refers to a group that is added to an oxygen, nitrogen, or phosphorus atom to prevent its further reaction or for other purposes. A wide variety of oxygen and nitrogen protecting groups are known to those skilled in the art of organic synthesis.
The term"aryl", as used herein, and unless otherwise specified, refers to phenyl, biphenyl, or naphthyl, and preferably phenyl. The term includes both substituted and unsubstituted moieties. The aryl group can be substituted with any described moiety, including, but not limited to, one or more moieties selected from the group consisting of halogen (fluoro, chloro, bromo or iodo), hydroxyl, amino, alkylamino, arylamino, alkoxy, aryloxy, nitro, cyano, sulfonic acid, sulfate, phosphonic acid, phosphate, or phosphonate, either unprotected, or protected as necessary, as known to those skilled in the art, for example, as taught in Greene, et al., Protective Groups in Organic Synthesis, John Wiley and Sons, Second Edition, 1991.
The term"alkaryl"or"alkylaryl"refers to an alkyl group with an aryl substituent.
The term aralkyl or arylalkyl refers to an aryl group with an alkyl substituent.
The term"halo", as used herein, includes chloro, bromo, iodo, and fluoro.
The term"purine"or"pyrimidine"base includes, but is not limited to, adenine, N6- alkylpurines, N6-acylpurines (wherein acyl is C (O) (alkyl, aryl, alkylaryl, or arylalkyl), N6- benzylpurine, N6-halopurine, N6-vinylpurine, N6-acetylenic purine, N6-acyl purine, N6-hydroxyalkyl purine, N6-alkylaminopurine, N6-thioalkyl purine, N 2-alkylpurines, N 2_ alkyl-6-thiopurines, thymine, cytosine, 5-fluorocytosine, 5-methylcytosine, 6-azapyrimidine, including 6-azacytosine, 2-and/or 4-mercaptopyrmidine, uracil, 5-halouracil, including 5-fluorouracil, C5-alkylpyrimidines, C5-benzylpyrimidines, C5-halopyrimidines, C5-vinylpyrimidine, C5-acetylenic pyrimidine, C5-acyl pyrimidine, C5-hydroxyalkyl purine, <BR> <BR> <BR> C5-amidopyrimidine, C5-cyanopyrimidine,, CS-iodopyrimidine, C6-iodo-pyrimidine, C5-Br- vinyl pyrimidine, C6-Br-vinyl pyrimidine, C5-nitropyrimidine, C5-amino-pyrimidine, N2- alkylpurines, N2-alkyl-6-thiopurines, 5-azacytidinyl, 5-azauracilyl, triazolopyridinyl, imidazolopyridinyl, pyrrolopyrimidinyl, and pyrazolopyrimidinyl. Purine bases include, but are not limited to, guanine, adenine, hypoxanthine, 2,6-diaminopurine, and 6-chloropurine.
Functional oxygen and nitrogen groups on the base can be protected as necessary or desired.
Suitable protecting groups are well known to those skilled in the art, and include trimethylsilyl, dimethylhexylsilyl, t-butyldimethylsilyl, and t-butyldiphenylsilyl, trityl, alkyl groups, and acyl groups such as acetyl and propionyl, methanesulfonyl, and p- toluenesulfonyl.
The term"acyl"or"O-linked ester"refers to a group of the formula C (O) R', wherein R'is an straight, branched, or cyclic alkyl (including lower alkyl), carboxylate reside of amino acid, aryl including phenyl, alkaryl, aralkyl including benzyl, alkoxyalkyl including methoxymethyl, aryloxyalkyl such as phenoxymethyl ; or substituted alkyl (including lower alkyl), aryl including phenyl optionally substituted with chloro, bromo, fluoro, iodo, Cl to C4 alkyl or C, to C4 alkoxy, sulfonate esters such as alkyl or aralkyl sulphonyl including methanesulfonyl, the mono, di or triphosphate ester, trityl or monomethoxy-trityl, substituted benzyl, alkaryl, aralkyl including benzyl, alkoxyalkyl including methoxymethyl, aryloxyalkyl such as phenoxymethyl. Aryl groups in the esters optimally comprise a phenyl group. In particular, acyl groups include acetyl, trifluoroacetyl, methylacetyl, cyclpropylacetyl, propionyl, butyryl, hexanoyl, heptanoyl, octanoyl, neo-heptanoyl, phenylacetyl, 2-acetoxy-2- phenylacetyl, diphenylacetyl, a-methoxy-a-trifluoromethyl-phenylacetyl, bromoacetyl, 2- nitro-benzeneacetyl, 4-chloro-benzeneacetyl, 2-chloro-2, 2-diphenylacetyl, 2-chloro-2- phenylacetyl, trimethylacetyl, chlorodifluoroacetyl, perfluoroacetyl, fluoroacetyl, bromodifluoroacetyl, methoxyacetyl, 2-thiopheneacetyl, chlorosulfonylacetyl, 3- methoxyphenylacetyl, phenoxyacetyl, tert-butylacetyl, trichloroacetyl, monochloro-acetyl, dichloroacetyl, 7H-dodecafluoro-heptanoyl, perfluoro-heptanoyl, 7H-dodeca- fluoroheptanoyl, 7-chlorododecafluoro-heptanoyl, 7-chloro-dodecafluoro-heptanoyl, 7H- dodecafluoroheptanoyl, 7H-dodeca-fluoroheptanoyl, nona-fluoro-3, 6-dioxa-heptanoyl, nonafluoro-3, 6-dioxaheptanoyl, perfluoroheptanoyl, methoxybenzoyl, methyl 3-amino-5- phenylthiophene-2-carboxyl, 3, 6-dichloro-2-methoxy-benzoyl, 4- (1, 1, 2, 2-tetrafluoro-ethoxy)- benzoyl, 2-bromo-propionyl, omega-aminocapryl, decanoyl, n-pentadecanoyl, stearyl, 3- cyclopentyl-propionyl, I-benzene-carboxyl, O-acetylmandelyl, pivaloyl acetyl, 1- adamantane-carboxyl, cyclohexane-carboxyl, 2, 6-pyridinedicarboxyl, cyclopropane-carboxyl, cyclobutane-carboxyl, perfluorocyclohexyl carboxyl, 4-methylbenzoyl, chloromethyl isoxazolyl carbonyl, perfluorocyclohexyl carboxyl, crotonyl, 1-methyl-IH-indazole-3- carbonyl, 2-propenyl, isovaleryl, I-pyrrolidinecarbonyl, 4-phenylbenzoyl.
The term"amino acid"includes naturally occurring and synthetic a, p y or 6 amino acids, and includes but is not limited to, amino acids found in proteins, i. e. glycine, alanine,
valine, leucine, isoleucine, methionine, phenylalanine, tryptophan, proline, serine, threonine, cysteine, tyrosine, asparagine, glutamine, aspartate, glutamate, lysine, arginine and histidine.
In a preferred embodiment, the amino acid is in the L-configuration. Alternatively, the amino acid can be a derivative of alanyl, valinyl, leucinyl, isoleuccinyl, prolinyl, phenylalaninyl, tryptophanyl, methioninyl, glycinyl, serinyl, threoninyl, cysteinyl, tyrosinyl, asparaginyl, glutaminyl, aspartoyl, glutaroyl, lysinyl, argininyl, histidinyl, (3-alanyl, (3-valinyl, p-leucinyl, P-isoleuccinyl, p-prolinyl, p-phenylalaninyl, P-tryptophanyl, p-methioninyl, p-glycinyl, ß- serinyl, ß-threoninyl, P-cysteinyl, (3-tyrosinyl, ß-asparaginyl, P-glutaminyl, P-aspartoyl, i- glutaroyl, (3-lysinyl, ß-argininyl or ß-histidinyl.
As used herein, the term"substantially free of'or"substantially in the absence of' refers to a nucleoside composition that includes at least 85 or 90% by weight, preferably 95%, 98 %, 99% or 100% by weight, of the designated enantiomer of that nucleoside. In a preferred embodiment, in the methods and compounds of this invention, the compounds are substantially free of enantiomers.
Similarly, the term"isolated"refers to a nucleoside composition that includes at least 85,90%, 95%, 98%, 99% to 100% by weight, of the nucleoside, the remainder comprising other chemical species or enantiomers.
The term"host", as used herein, refers to an unicellular or multicellular organism in which the virus can replicate, including cell lines and animals, and preferably a human.
Alternatively, the host can be carrying a part of the Flaviviridae viral genome, whose replication or function can be altered by the compounds of the present invention. The term host specifically refers to infected cells, cells transfected with all or part of the Flaviviridae genome and animals, in particular, primates (including chimpanzees) and humans. In most animal applications of the present invention, the host is a human patient. Veterinary applications, in certain indications, however, are clearly anticipated by the present invention (such as chimpanzees).
The term"pharmaceutically acceptable salt or prodrug"is used throughout the specification to describe any pharmaceutically acceptable form (such as an ester, phosphate ester, salt of an ester or a related group) of a nucleoside compound which, upon administration to a patient, provides the nucleoside compound. Pharmaceutically acceptable salts include those derived from pharmaceutically acceptable inorganic or organic bases and acids. Suitable salts include those derived from alkali metals such as potassium and sodium,
alkaline earth metals such as calcium and magnesium, among numerous other acids well known in the pharmaceutical art. Pharmaceutically acceptable prodrugs refer to a compound that is metabolized, for example hydrolyzed or oxidized, in the host to form the compound of the present invention. Typical examples of prodrugs include compounds that have biologically labile protecting groups on a functional moiety of the active compound.
Prodrugs include compounds that can be oxidized, reduced, aminated, deaminated, hydroxylated, dehydroxylated, hydrolyzed, dehydrolyzed, alkylated, dealkylated, acylated, deacylated, phosphorylated, dephosphorylated to produce the active compound. The compounds of this invention possess antiviral activity against a Flaviviridae, or are metabolized to a compound that exhibits such activity.
III. Prodrugs and Derivatives Pharmaceutically Aceptable Salts In cases where compounds are sufficiently basic or acidic to form stable nontoxic acid or base salts, administration of the compound as a pharmaceutically acceptable salt may be appropriate. Examples of pharmaceutically acceptable salts are organic acid addition salts formed by addition of acids, which form a physiological acceptable anion, for example, tosylate, methanesulfonate, acetate, citrate, malonate, tartarate, succinate, benzoate, ascorate, a-ketoglutarate, a-glycerophosphate, formate, fumarate, propionate, glycolate, lactate, pyruvate, oxalate, maleate, and salicylate. Suitable inorganic salts may also be formed, including, sulfate, nitrate, bicarbonate, carbonate salts, hydrobromate and phosphoric acid. In a preferred embodiment, the salt is a mono-or di-hydrochloride salt.
Pharmaceutically acceptable salts may be obtained using standard procedures well known in the art, for example by reacting a sufficiently basic compound such as an amine with a suitable acid affording a physiologically acceptable anion. Alkali metal (for example, sodium, potassium or lithium) or alkaline earth metal (for example calcium) salts of carboxylic acids can also be made. In one embodiment, the salt is a hydrochloride salt of the compound. In a further embodiment, the pharmaceutically acceptable salt is a dihydrochloride salt.
Nucleotide Prodrug Formulations The nucleosides described herein can be administered as a nucleotide prodrug to increase the activity, bioavailability, stability or otherwise alter the properties of the nucleoside. A number of nucleotide prodrug ligands are known. In general, alkylation, acylation or other lipophilic modification of the mono-, di-or triphosphate of the nucleoside reduces polarity and allows passage into cells. Examples of substituent groups that can replace one or more hydrogens on the phosphate moiety are alkyl, aryl, steroids, carbohydrates, including sugars, 1, 2-diacylglycerol and alcohols.
In an alternative embodiment, the compound is administered as a phosphonate, phosphorothioate or SATE derivative.
Many are described in R. Jones and N. Bischoferger, Antiviral Research, 1995, 27 : 1- 17. Any of these can be used in combination with the disclosed nucleosides to achieve a desired effect. Nonlimiting examples of U. S. patents that disclose suitable lipophilic substituents that can be covalently incorporated into the nucleoside, preferably at the 5'-OH position of the nucleoside or lipophilic preparations, include U. S. Patent Nos. 5,149, 794 (Sep.
22,1992, Yatvin et al.) ; 5,194, 654 (Mar. 16,1993, Hostetler et al., 5,223, 263 (June 29,1993, Hostetler et al.) ; 5,256, 641 (Oct. 26,1993, Yatvin et al.) ; 5,411, 947 (May 2,1995, Hostetler et al.) ; 5,463, 092 (Oct. 31,1995, Hostetler et al.) ; 5,543, 389 (Aug. 6,1996, Yatvin et al.) ; 5,543, 390 (Aug. 6,1996, Yatvin et al.) ; 5,543, 391 (Aug. 6,1996, Yatvin et al.) ; and 5,554, 728 (Sep. 10,1996 ; Basava et al.), all of which are incorporated herein by reference.
Foreign patent applications that disclose lipophilic substituents that can be attached to the nucleosides of the present invention, or lipophilic preparations, include WO 89/02733, WO 90/00555, WO 91/16920, WO 91/18914, WO 93/00910, WO 94/26273, WO 96/15132, EP 0 350 287, EP 93917054.4, and WO 91/19721.
The active nucleoside can also be provided as a 2', 3'and/or 5'-phosphoether lipid or a 2', 3'and/or 5'-ether lipid, as disclosed in the following references, which are incorporated by reference herein: Kucera, L. S. , N. Iyer, et al. 1990 AIDS Res. Hum. Retro Viruses. 6: 491- 501; Piantadosi, C. , J. Marasco C. J. , et al. 1991 J. Med Chem. 34: 1408.1414 ; Hosteller, K. Y. , D. D. Richman, et al. 1992 Antimicrob. Agents Chemother. 36: 2025.2029 ; Hosetler, K. Y. , L. M. Stuhmiller, 1990. J. Biol. Chem. 265: 61127.
Nonlimiting examples of U. S. patents that disclose suitable lipophilic substituents that can be covalently incorporated into the nucleoside, preferably at the 2', 3'and/or 5'-OH
position of the nucleoside or lipophilic preparations, include U. S. Patent Nos. 5,149, 794 (Sep.
22,1992, Yatvin et al.) ; 5,194, 654 (Mar. 16,1993, Hostetler et al., 5,223, 263 (June 29, 1993, Hostetler et al.) ; 5,256, 641 (Oct. 26,1993, Yatvin et al.) ; 5,411, 947 (May 2,1995, Hostetler et al.) ; 5,463, 092 (Oct. 31,1995, Hostetler et al.) ; 5,543, 389 (Aug. 6,1996, Yatvin et al.) ; 5,543, 390 (Aug. 6,1996, Yatvin et al.) ; 5,543, 391 (Aug. 6,1996, Yatvin et al.) ; and 5,554, 728 (Sep. 10,1996 ; Basava et al.), all of which are incorporated herein by reference.
Foreign patent applications that disclose lipophilic substituents that can be attached to the nucleosides of the present invention, or lipophilic preparations, include WO 89/02733, WO 90/00555, WO 91/16920, WO 91/18914, WO 93/00910, WO 94/26273, WO 96/15132, EP 0 350 287, EP 93917054.4, and WO 91/19721.
Aryl esters, especially phenyl esters, are also provided. Nonlimiting examples are disclosed in DeLambert et al., J. Med. Chem. 37: 498 (1994). Phenyl esters containing a carboxylic ester ortho to the phosphate are also provided. Khamnei and Torrence, J. Med Chem. ; 39: 4109-4115 (1996). In particular, benzyl esters, which generate the parent compound, in some cases using substituents at the ortho-or para-position to accelerate hydrolysis, are provided. Examples of this class of prodrugs are described by Mitchell et al., J. Chem. Soc. Perkin Trans. I 2345 (1992); Brook, et al. WO 91/19721; and Glazier et al.
WO 91/19721.
Cyclic phosphonate esters are also provided. Nonlimiting examples are disclosed in Hunston et al., J. Med. Chem. 27: 440-444 (1984) and Starrett et al. J. Med. Chem. 37: 1857- 1864 (1994). Additionally, cyclic 3', 5'-phosphate esters are provided. Nonlimiting examples are disclosed in Meier et al. J. Med. Chem. 22: 811-815 (1979). Cyclic 1', 3'-propanyl phosphonate and phosphate esters, such as ones containing a fused aryl ring, i. e. the cyclosaligenyl ester, are also provided (Meier et al., Bioorg. Med. Chem. Lett. 7: 99-104 (1997) ). Unsubstituted cyclic 1', 3'-propanyl esters of the monophosphates are also provided (Farquhar et al., J. Med. Chem. 26: 1153 (1983); Farquhar et al., J. Med Chem. 28: 1358 (1985) ) were prepared. In addition, cyclic 1', 3'-propanyl esters substituted with a pivaloyloxy methyloxy group at C-l'are provided (Freed et al., Biochem. Pharmac. 38: 3193 (1989); Biller et al. , U. S. Pat. No. 5,157, 027).
Cyclic phosphoramidates are known to cleave in vivo by an oxidative mechanism.
Therefore, in one embodiment of the present invention, a variety of substituted 1', 3' propanyl cyclic phosphoramidates are provided. Non-limiting examples are disclosed by Zon, Progress in Med. Chem. 19,1205 (1982). Additionally, a number of 2'-and 3'-substituted
proesters are provided. 2'-Substituents include methyl, dimethyl, bromo, trifluoromethyl, chloro, hydroxy, and methoxy; 3'-substituents including phenyl, methyl, trifluoromethyl, ethyl, propyl, i-propyl, and cyclohexyl. A variety of 1'-substituted analogs are also provided.
Cyclic esters of phosphorus-containing compounds are also provided. Non-limiting examples are described in the following: * [1] di and tri esters of phosphoric acids as reported in Nifantyev et al., Phosphorus, SulfurSilicon and Related Eelements, 113: 1 (1996); Wijnberg et al. , EP-180276 Al ; [2] phosphorus (III) acid esters. Kryuchkov et al., Izv. Akad. Nauk SSSR, Ser. Khim.
6: 1244 (1987). Some of the compounds were claimed to be useful for the asymmetric synthesis of L-Dopa precursors. Sylvain et al., DE3512781 Al ; [3] phosphoramidates. Shih et al., Bull. Inst. Chem. Acad Sin, 41: 9 (1994); Edmundson et al., J. Chem. Res. Synop. 5: 122 (1989); and [4] phosphonates. Neidlein et al., Heterocycles 35: 1185 (1993).
Further, nonlimiting examples of U. S. and International Patent Applications that disclose suitable cyclic phosphoramidate prodrugs include U. S. Patent No. 6,312, 662; WO 99/45016; WO 00/52015; WO 01/47935 ; and WO 01/18013 to Erion, et al. from Metabasis Therapeutics, Inc. Specifically, prodrugs of Formula A below are provided: wherein: together V and Z are connected via an additional 3-5 atoms to form a cyclic group containing 5-7 atoms, optionally 1 heteroatom, substituted with hydroxy, acyloxy, alkoxycarbonyloxy, or aryloxycarbonyloxy attached to a carbon atom that is three atoms from both O groups attached to the phosphorus; or
together V and Z are connected via an additional 3-5 atoms to form a cyclic group, optionally containing I heteroatom, that is fused to an aryl group at the beta and gamma position to the O attached to the phosphorus; # together V and W are connected via an additional 3 carbon atoms to form an optionally substituted cyclic group containing 6 carbon atoms and substituted with one substituent selected from the group consisting of hydroxy, acyloxy, alkoxycarbonyloxy, alkylthiocarbonyloxy, and aryloxycarbonyloxy, attached to one of said carbon atoms that is three atoms from an O attached to the phosphorus; # together Z and W are connected via an additional 3-5 atoms to form a cyclic group, optionally containing one heteroatom, and V must be aryl, substituted aryl, heteroaryl, or substituted heteroaryl ; # together W and W'are connected via an additional 2-5 atoms to form a cyclic group, optionally containing 0-2 heteroatoms, and V must be aryl, substituted aryl, heteroaryl, or substituted heteroaryl ; # Z is selected from the group consisting of -CHR2 OH, -CHR2 OC(O)R3, -CHR2 OC (S) R3,-CHR2 OC (S) OR3, -CHR2 OC (O) SR3,-CHR2 OCOz R3, -OR2, -SR2, -CHR2 <BR> <BR> <BR> N3,-CH2 aryl,-CH (aryl) OH, -CH (CH=CR22) OH, -CH (C. ident. CR2) OH,-R2,-NR22,-<BR> <BR> <BR> <BR> OCOR3,-OCO2 R3,-SCOR3,-SCO2 R3,-NHCORz,-NHCO2 R3,-CH2 NHaryl,- (CH2) p -OR12, and -(CH2)p -SR12 ; # p is an integer 2 or 3 ; # with the provisos that: a) V, Z, W, W'are not all-H ; and b) when Z is-R2, then at least one of V, W, and W'is not-H, alkyl, aralkyl, or alicyclic ; # R2 is selected from the group consisting of R3 and-H; # R3 is selected from the group consisting of alkyl, aryl, alicyclic, and aralkyl ; # R12 is selected from the group consisting of-H, and lower acyl ; M is the biologically active agent, and that is attached to the phosphorus in Formula A via the 2', 3'and/or 5'-hydroxyl.
IV. Combination or Alternation Therapy The active compounds of the present invention can be administered in combination or alternation with another anti-flavivirus or pestivirus agent, or in particular an anti-HCV agent.
In combination therapy, effective dosages of two or more agents are administered together, whereas in alternation or sequential-step therapy, an effective dosage of each agent is administered serially or sequentially. The dosages given will depend on absorption, inactivation and excretion rates of the drug as well as other factors known to those of skill in the art. It is to be noted that dosage values will also vary with the severity of the condition to be alleviated. It is to be further understood that for any particular subject, specific dosage regimens and schedules should be adjusted over time according to the individual need and the professional judgment of the person administering or supervising the administration of the compositions. In preferred embodiments, an anti-HCV (or anti-pestivirus or anti-flavivirus) compound that exhibits an EC50 of 10-15 pM, or preferably less than 1-5 uM, is desirable.
It has been recognized that drug-resistant variants of flaviviruses, pestiviruses or HCV can emerge after prolonged treatment with an antiviral agent. Drug resistance most typically occurs by mutation of a gene that encodes for an enzyme used in viral replication. The efficacy of a drug against the viral infection can be prolonged, augmented, or restored by administering the compound in combination or alternation with a second, and perhaps third, antiviral compound that induces a different mutation from that caused by the principle drug.
Alternatively, the pharmacokinetics, biodistribution or other parameter of the drug can be altered by such combination or alternation therapy. In general, combination therapy is typically preferred over alternation therapy because it induces multiple simultaneous stresses on the virus.
Any of the viral treatments described in the Background of the Invention can be used in combination or alternation with the compounds described in this specification. Nonlimiting examples include: 1) Protease inhibitors Examples include substrate-based NS3 protease inhibitors (Attwood et al., Antiviral peptide derivatives, PCT WO 98/22496,1998 ; Attwood et al., Antiviral Chemistry and Chemotherapy 1999,10, 259-273; Attwood et al., Preparation and use of amino acid derivatives as anti-viral agents, German Patent Pub. DE 19914474; Tung et al. Inhibitors of serine proteases, particularly hepatitis C virus NS3 protease, PCT WO 98/17679), including
alphaketoamides and hydrazinoureas, and inhibitors that terminate in an electrophile such as a boronic acid or phosphonate (Llinas-Brunet et al, Hepatitis C inhibitor peptide analogues, PCT WO 99/07734); Non-substrate-based NS3 protease inhibitors such as 2,4, 6-trihydroxy- 3-nitro-benzamide derivatives (Sudo K. et al., Biochemical and Biophysical Research Communications, 1997,238, 643-647; Sudo K. et al. Antiviral Chemistry and Chemotherapy, 1998,9, 186), including RD3-4082 and RD3-4078, the former substituted on the amide with a 14 carbon chain and the latter processing a para-phenoxyphenyl group; and Sch 68631, a phenanthrenequinone, an HCV protease inhibitor (Chu M. et al., Tetrahedron Letters 37: 7229-7232,1996).
Sch 351633, isolated from the fungus Penicillium griseofulvum, was identified as a protease inhibitor (Chu M. et al., Bioorganic and Medicinal Chemistry Letters 9: 1949-1952).
Eglin c, isolated from leech, is a potent inhibitor of several serine proteases such as S. griseus proteases A and B, a-chymotrypsin, chymase and subtilisin. Qasim M. A. et al., Biochemistry 36: 1598-1607,1997.
U. S. patents disclosing protease inhibitors for the treatment of HCV include, for example, U. S. Patent No. 6,004, 933 to Spruce et al. which discloses a class of cysteine protease inhibitors for inhibiting HCV endopeptidase 2; U. S. Patent No. 5,990, 276 to Zhang et al. which discloses synthetic inhibitors of hepatitis C virus NS3 protease; U. S. Patent No.
5,538, 865 to Reyes et a; WO 02/008251 to Corvas International, Inc, and WO 02/08187 and WO 02/008256 to Schering Corporation. HCV inhibitor tripeptides are disclosed in US Patent Nos. 6,534, 523,6, 410,531, and 6,420, 380 to Boehringer Ingelheim and WO 02/060926 to Bristol Myers Squibb. Diaryl peptides as NS3 serine protease inhibitors of HCV are disclosed in WO 02/48172 to Schering Corporation. Imidazoleidinones as NS3 serine protease inhibitors of HCV are disclosed in WO 02/08198 to Schering Corporation and WO 02/48157 to Bristol Myers Squibb. WO 98/17679 to Vertex Pharmaceutical and WO 02/48116 to Bristol Myers Squibb also disclose HCV protease inhibitors.
2) Thiazolidine derivatives which show relevant inhibition in a reverse-phase HPLC assay with an NS3/4A fusion protein and NS5A/5B substrate (Sudo K. et al., Antiviral Research, 1996,32, 9-18), especially compound RD-1-6250, possessing a fused cinnamyl moiety substituted with a long alkyl chain, RD4 6205 and RD4 6193;
3) Thiazolidines and benzanilides identified in Kakiuchi N. et al. J. EBS Letters 421,217-220 ; Takeshita N. et al. Analytical Biochemistry, 1997,247, 242-246; 4) A phenan-threnequinone possessing activity against protease in a SDS-PAGE and autoradiography assay isolated from the fermentation culture broth of Streptomyces sp. , Sch 68631 (Chu M. et al., Tetrahedron Letters, 1996,37, 7229-7232), and Sch 351633, isolated from the fungus Penicillium griseofulvum, which demonstrates activity in a scintillation proximity assay (Chu M. et al., Bioorganic and Medicinal Chemistry Letters 9,1949-1952) ; 5) Helicase inhibitors (Diana G. D. et al., Compounds, compositions and methods for treatment of hepatitis C, U. S. Pat. No. 5,633, 358; Diana G. D. et al., Piperidine derivatives, pharmaceutical compositions thereof and their use in the treatment of hepatitis C, PCT WO 97/36554); 6) Nucleotide polymerase inhibitors and gliotoxin (Ferrari R. et al. Journal of Virology, 1999,73, 1649-1654), and the natural product cerulenin (Lohmann V. et al., Virology, 1998,249, 108-118); 7) Antisense phosphorothioate oligodeoxynucleotides (S-ODN) complementary to sequence stretches in the 5'non-coding region (NCR) of the virus (Alt M. et al., Hepatology, 1995,22, 707-717), or nucleotides 326-348 comprising the 3'end of the NCR and nucleotides 371-388 located in the core coding region of the HCV RNA (Alt M. et al., Archives of Virology, 1997,142, 589-599; Galderisi U. et al., Journal of Cellular Physiology, 1999,181, 251-257); 8) Inhibitors of IRES-dependent translation (Ikeda N et al. , Agent for the prevention and treatment of hepatitis C, Japanese Patent Pub. JP-08268890; Kai
Y. et al. Prevention and treatment of viral diseases, Japanese Patent Pub. JP- 10101591); 9) Ribozymes, such as nuclease-resistant ribozymes (Maccjak, D. J. et al., Hepatology 1999,30, abstract 995) and those disclosed in U. S. Patent No.
6,043, 077 to Barber et al. , and U. S. Patent Nos. 5,869, 253 and 5,610, 054 to Draper et al.; and 10) Nucleoside analogs have also been developed for the treatment of Flaviviridae infections.
11) Any of the compounds described by Idenix Pharmaceuticals in International Publication Nos. WO 01/90121 and WO 01/92282 ;.
12) Other patent applications disclosing the use of certain nucleoside analogs to treat hepatitis C virus include: PCT/CA00/01316 (WO 01/32153 ; filed November 3, 2000) and PCT/CA01/00197 (WO 01/60315 ; filed February 19,2001) filed by BioChem Pharma, Inc. (now Shire Biochem, Inc. ) ; PCT/US02/01531 (WO 02/057425; filed January 18,2002) and PCT/US02/03086 (WO 02/057287; filed January 18,2002) filed by Merck & Co. , Inc., PCT/EP01/09633 (WO 02/18404; published August 21,2001) filed by Roche, and PCT Publication Nos. WO 01/79246 (filed April 13,2001), WO 02/32920 (filed October 18,2001) and WO 02/48165 by Pharmasset, Ltd.
13) PCT Publication No. WO 99/43691 to Emory University, entitled"2'- Fluoronucleosides"discloses the use of certain 2'-fluoronucleosides to treat HCV.
14) Other miscellaneous compounds including l-amino-alkylcyclohexanes (U. S.
Patent No. 6,034, 134 to Gold et al.), alkyl lipids (U. S. Pat. No. 5,922, 757 to
Chojkier et al.), vitamin E and other antioxidants (U. S. Pat. No. 5,922, 757 to Chojkier et al.), squalene, amantadine, bile acids (U. S. Pat. No. 5,846, 964 to Ozeki et al.), N- (phosphonoacetyl)-L-aspartic acid, (U. S. Pat. No. 5,830, 905 to Diana et al.), benzenedicarboxamides (U. S. Pat. No. 5,633, 388 to Diana et al.), polyadenylic acid derivatives (U. S. Pat. No. 5,496, 546 to Wang et al.), 2', 3'- dideoxyinosine (U. S. Pat. No. 5,026, 687 to Yarchoan et al.), benzimidazoles (U. S. Pat. No. 5,891, 874 to Colacino et al.), plant extracts (U. S. Patent No.
5,837, 257 to Tsai et al., U. S. Patent No. 5,725, 859 to Omer et al., and U. S.
Patent No. 6,056, 961), and piperidenes (U. S. Patent No. 5,830, 905 to Diana et al.).
15) Any other compounds currently in preclinical or clinical development for treatment of hepatitis C virus including: Interleukin-10 by Schering-Plough, IP- 501 by Interneuron, Merimebodib (VX-497) by Vertex, AMANTADINEO (Symmetrel) by Endo Labs Solvay, HEPTAZYME (g) by RPI, IDN-6556 by Idun Pharma. , XTL-002 by XTL. , HCV/MF59 by Chiron, CIVACIRS (Hepatitis C Immune Globulin) by NABI, LEVOVIRINX by ICN/Ribapharm, VIRAMIDINE (g) by ICN/Ribapharm, ZADAXINX) (thymosin alpha-1) by Sci Clone, thymosin plus pegylated interferon by Sci Clone, CEPLENEX (histamine dihydrochloride) by Maxim, VX 950/LY 570310 by Vertex/Eli Lilly, ISIS 14803 by Isis Pharmaceutical/Elan, IDN-6556 by Idun Pharmaceuticals, Inc. , JTK 003 by AKROS Pharma, BILN-2061 by Boehringer Ingelheim, CellCept (mycophenolate mofetil) by Roche, T67, a ß-tubulin inhibitor, by Tularik, a therapeutic vaccine directed to E2 by Innogenetics, FK788 by Fujisawa Healthcare, Inc. , IdB 1016 (Siliphos, oral silybin- phosphatdylcholine phytosome), RNA replication inhibitors (VP50406) by ViroPharma/Wyeth, therapeutic vaccine by Intercell, therapeutic vaccine by Epimmune/Genencor, IRES inhibitor by Anadys, ANA 245 and ANA 246 by Anadys, immunotherapy (Therapore) by Avant, protease inhibitor by Corvas/SChering, helicase inhibitor by Vertex, fusion inhibitor by Trimeris, T cell therapy by CellExSys, polymerase inhibitor by Biocryst, targeted RNA chemistry by PTC Therapeutics, Dication by Immtech, Int. , protease inhibitor by Agouron, protease inhibitor by Chiron/Medivir, antisense therapy by AVI
BioPharma, antisense therapy by Hybridon, hemopurifier by Aethlon Medical, therapeutic vaccine by Merix, protease inhibitor by Bristol-Myers Squibb/Axys, Chron-VacC, a therapeutic vaccine, by Tripep, UT 231B by United Therapeutics, protease, helicase and polymerase inhibitors by Genelabs Technologies, IRES inhibitors by Immusol, R803 by Rigel Pharmaceuticals, INFERGEN (T (interferon alphacon-1) by InterMune, OMNIFERON (natural interferon) by Viragen, ALBUFERONS by Human Genome Sciences, REBIFS (interferon beta-la) by Ares-Serono, Omega Interferon by BioMedicine, Oral Interferon Alpha by Amarillo Biosciences, interferon gamma, interferon tau, and Interferon gamma- ! b by InterMune.
V. Pharmaceutical Compositions Hosts, including humans, infected with pestivirus, flavivirus, HCV or another organism replicating through a RNA-dependent RNA viral polymerase, or for treating any other disorder described herein, can be treated by administering to the patient an effective amount of the active compound or a pharmaceutically acceptable prodrug or salt thereof in the presence of a pharmaceutically acceptable carrier or diluent. The active materials can be administered by any appropriate route, for example, orally, parenterally, intravenously, intradermally, subcutaneously, or topically, in liquid or solid form.
A preferred dose of the compound for pestivirus, flavivirus or HCV infection or any other condition described herein will be in the range from about 1 to 50 mg/kg, preferably 1 to 20 mg/kg, of body weight per day, more generally 0.1 to about 100 mg per kilogram body weight of the recipient per day. Lower doses may be preferable, for example doses of 0.5- 100 mg, 0.5-50 mg, 0.5-10 mg, or 0.5-5 mg per kilogram body weight per day. Even lower doses may be useful, and thus ranges can also include from 0.1-0. 5 mg per kilogram body weight per day. The effective dosage range of the pharmaceutically acceptable salts and prodrugs can be calculated based on the weight of the parent nucleoside to be delivered. If the salt or prodrug exhibits activity in itself, the effective dosage can be estimated as above using the weight of the salt or prodrug, or by other means known to those skilled in the art.
The compound is conveniently administered in a unit of any suitable dosage form, including but not limited to one containing 7 to 3000 mg, preferably 70 to 1400 mg of active
ingredient per unit dosage form. An oral dosage of 50-1000 mg is usually convenient, including in one or multiple dosages of 50,100, 200,250, 300,400, 500,600, 700,800, 900 or 1000 mgs. Lower doses may be preferable, for example from 10-100 or 1-50 mg. Also contemplated are doses of 0.1-50 mg, or 0.1-20 mg or 0.1-10. 0 mg. Furthermore, lower doses may be utilized in the case of administration by a non-oral route, as, for example, by injection or inhalation.
Ideally the active ingredient should be administered to achieve peak plasma concentrations of the active compound of from about 0.2 to 70 pLM, preferably about 1.0 to 10 uM. This may be achieved, for example, by the intravenous injection of a 0.1 to 5% solution of the active ingredient, optionally in saline, or administered as a bolus of the active ingredient.
The concentration of active compound in the drug composition will depend on absorption, inactivation and excretion rates of the drug as well as other factors known to those of skill in the art. It is to be noted that dosage values will also vary with the severity of the condition to be alleviated. It is to be further understood that for any particular subject, specific dosage regimens should be adjusted over time according to the individual need and the professional judgment of the person administering or supervising the administration of the compositions, and that the concentration ranges set forth herein are exemplary only and are not intended to limit the scope or practice of the claimed composition. The active ingredient may be administered at once, or may be divided into a number of smaller doses to be administered at varying intervals of time.
A preferred mode of administration of the active compound is oral. Oral compositions will generally include an inert diluent or an edible carrier. They may be enclosed in gelatin capsules or compressed into tablets. For the purpose of oral therapeutic administration, the active compound can be incorporated with excipients and used in the form of tablets, troches, or capsules. Pharmaceutically compatible binding agents, and/or adjuvant materials can be included as part of the composition.
The tablets, pills, capsules, troches and the like can contain any of the following ingredients, or compounds of a similar nature: a binder such as microcrystalline cellulose, gum tragacanth or gelatin; an excipient such as starch or lactose, a disintegrating agent such as alginic acid, Primogel, or corn starch; a lubricant such as magnesium stearate or Sterotes; a glidant such as colloidal silicon dioxide; a sweetening agent such as sucrose or saccharin; or a
flavoring agent such as peppermint, methyl salicylate, or orange flavoring. When the dosage unit form is a capsule, it can contain, in addition to material of the above type, a liquid carrier such as a fatty oil. In addition, dosage unit forms can contain various other materials which modify the physical form of the dosage unit, for example, coatings of sugar, shellac, or other enteric agents.
The compound can be administered as a component of an elixir, suspension, syrup, wafer, chewing gum or the like. A syrup may contain, in addition to the active compounds, sucrose as a sweetening agent and certain preservatives, dyes and colorings and flavors.
The compound or a pharmaceutically acceptable prodrug or salts thereof can also be mixed with other active materials that do not impair the desired action, or with materials that supplement the desired action, such as antibiotics, antifungals, anti-inflammatories, or other antivirals, including other nucleoside compounds. Solutions or suspensions used for parenteral, intradermal, sucutaneous, or topical application can include the following components: a sterile diluent such as water for injection, saline solution, fixed oils, polyethylene glycols, glycerine, propylene glycol or other synthetic solvents; antibacterial agents such as benzyl alcohol or methyl parabens; antioxidants such as ascorbic acid or sodium bisulfite; chelating agents such as ethylenediaminetetraacetic acid; buffers such as acetates, citrates or phosphates and agents for the adjustment of tonicity such as sodium chloride or dextrose. The parental preparation can be enclosed in ampoules, disposable syringes or multiple dose vials made of glass or plastic.
If administered intravenously, preferred carriers are physiological saline or phosphate buffered saline (PBS).
In a preferred embodiment, the active compounds are prepared with carriers that will protect the compound against rapid elimination from the body, such as a controlled release formulation, including implants and microencapsulated delivery systems. biodegradable, biocompatible polymers can be used, such as ethylene vinyl acetate, polyanhydrides, polyglycolic acid, collagen, polyorthoesters and polylactic acid. Methods for preparation of such formulations will be apparent to those skilled in the art. The materials can also be obtained commercially from Alza Corporation.
Liposomal suspensions (including liposomes targeted to infected cells with monoclonal antibodies to viral antigens) are also preferred as pharmaceutically acceptable carriers. These may be prepared according to methods known to those skilled in the art, for
example, as described in U. S. Patent No. 4,522, 811 (which is incorporated herein by reference in its entirety). For example, liposome formulations may be prepared by dissolving appropriate lipid (s) (such as stearoyl phosphatidyl ethanolamine, stearoyl phosphatidyl choline, arachadoyl phosphatidyl choline, and cholesterol) in an inorganic solvent that is then evaporated, leaving behind a thin film of dried lipid on the surface of the container. An aqueous solution of the active compound or its monophosphate, diphosphate, and/or triphosphate derivatives is then introduced into the container. The container is then swirled by hand to free lipid material from the sides of the container and to disperse lipid aggregates, thereby forming the liposomal suspension.
VI. Processes for the Preparation of Active Compounds The nucleosides of the present invention can be synthesized by any means known in the art. In particular, the synthesis of the present nucleosides can be achieved by either alkylating the appropriately modified sugar, followed by glycosylation or glycosylation followed by alkylation of the nucleoside. The following non-limiting embodiments illustrate some general methodology to obtain the nucleosides of the present invention.
A. General Synthesis of 1'-C-Branched Nucleosides 1'-C-Branched ribonucleosides of the following structure: wherein BASE is a purine or pyrimidine base as defined herein; R7 and R9 are independently hydrogen, OR2, hydroxy, alkyl (including lower alkyl), azido, cyano, alkenyl, alkynyl, Br-vinyl,-C (O) O (alkyl),-C (O) O (lower alkyl),-O (acyl),-O (lower acyl),-O (alkyl),-O (lower alkyl),-O (alkenyl), chlorine, bromine, iodine, NO2, NH2, -NH (lower alkyl),-NH (acyl),-N (lower alkyl) 2,-N (acyl) 2 ; R8 and Rl° are independently H, alkyl (including lower alkyl), chlorine, bromine or iodine;
alternatively, R7 and R9, R7 and Rl°, R8 and R9, or R8 and Rl° can come together to form a pi bond; R'and R2 are independently H; phosphate (including monophosphate, diphosphate, triphosphate, or a stabilized phosphate prodrug); acyl (including lower acyl) ; alkyl (including lower alkyl) ; sulfonate ester including alkyl or arylalkyl sulfonyl including methanesulfonyl and benzyl, wherein the phenyl group is optionally substituted with one or more substituents as described in the definition of aryl given herein; a lipid, including a phospholipid ; an amino acid; a carbohydrate; a peptide; cholesterol; or other pharmaceutically acceptable leaving group which is capable of providing a compound wherein Rl or R2 is independently H or phosphate, for example when administered in vivo ; R6 is an alkyl, chloro-, bromo-, fluoro-, or iodo-alkyl (i. e. CF3), alkenyl, or alkynyl (i. e. allyl) ; and X is O, S, SO2 or CH2 can be prepared by one of the following general methods.
1) Modification from the lactone The key starting material for this process is an appropriately substituted lactone. The lactone can be purchased or can be prepared by any known means including standard epimerization, substitution and cyclization techniques. The lactone can be optionally protected with a suitable protecting group, preferably with an acyl or silyl group, by methods well known to those skilled in the art, as taught by Greene et al. Protective Groups in Organic Synthesis, John Wiley and Sons, Second Edition, 1991. The protected lactone can then be coupled with a suitable coupling agent, such as an organometallic carbon nucleophile, such as a Grignard reagent, an organolithium, lithium dialkylcopper or R6-SiMe3 in TBAF with the appropriate non-protic solvent at a suitable temperature, to give the I'-alkylated sugar.
The optionally activated sugar can then be coupled to the BASE by methods well known to those skilled in the art, as taught by Townsend Chemistry of Nucleosides and Nucleotides, Plenum Press, 1994. For example, an acylated sugar can be coupled to a silylated base with a Lewis acid, such as tin tetrachloride, titanium tetrachloride or trimethylsilyltriflate in the appropriate solvent at a suitable temperature.
Subsequently, the nucleoside can be deprotected by methods well known to those skilled in the art, as taught by Greene et al. Protective Groups in Organic Synthesis, John Wiley and Sons, Second Edition, 1991.
In a particular embodiment, the I'-C-branched ribonucleoside is desired. The synthesis of a ribonucleoside is shown in Scheme 1. Alternatively, deoxyribo-nucleoside is desired. To obtain these nucleosides, the formed ribonucleoside can optionally be protected by methods well known to those skilled in the art, as taught by Greene et al. Protective Groups in Organic Synthesis, John Wiley and Sons, Second Edition, 1991, and then the 2'- OH can be reduced with a suitable reducing agent. Optionally, the 2'-hydroxyl can be activated to facilitate reduction; i. e. via the Barton reduction.
Scheme 1 HO R'O R'o HO 0 Optional RIO 0 1) R6. M Ri0) O-LG' 6 OH OH Protection oR2 OR3 2) Optional pR2 OR3R Activation 1) Coupling 2) Optional Deprotection BASE I) Optional BASE Protection -------------- T, R' 2) Optional R' Reduction OH OH Optional Deprotection V BASE HO O R6 9 ; t6 OH
2. Alternative method for the preparation of l'-C-branched nucleosides The key starting material for this process is an appropriately substituted hexose. The hexose can be purchased or can be prepared by any known means including standard epimerization, such as alkaline treatment, substitution and coupling techniques. The hexose
can be selectively protected to give the appropriate hexa-furanose, as taught by Townsend Chemistry of Nucleosides and Nucleotides, Plenum Press, 1994.
The l'-hydroxyl can be optionally activated to a suitable leaving group such as an acyl group or a chloro, bromo, fluoro, iodo via acylation or halogenation, respectively. The optionally activated sugar can then be coupled to the BASE by methods well known to those skilled in the art, as taught by Townsend Chemistry of Nucleosides and Nucleotides, Plenum Press, 1994. For example, an acylated sugar can be coupled to a silylated base with a Lewis acid, such as tin tetrachloride, titanium tetrachloride or trimethylsilyltriflate in the appropriate solvent at a suitable temperature. Alternatively, a halo-sugar can be coupled to a silylated base with the presence of trimethylsilyltriflate.
The 1'-CH2-OH, if protected, can be selectively deprotected by methods well known in the art. The resultant primary hydroxyl can be functionalized to yield various C-branched nucleosides. For example, the primary hydroxyl can be reduced to give the methyl, using a suitable reducing agent. Alternatively, the hydroxyl can be activated prior to reduction to facilitate the reaction; i. e. via the Barton reduction. In an alternate embodiment, the primary hydroxyl can be oxidized to the aldehyde, then coupled with a carbon nucleophile, such as a Grignard reagent, an organolithium, lithium dialkylcopper or R6-SiMe3 in TBAF with the appropriate non-protic solvent at a suitable temperature.
In a particular embodiment, the 1'-C-branched ribonucleoside is desired. The synthesis of a ribonucleoside is shown in Scheme 2. Alternatively, deoxyribo-nucleoside is desired. To obtain these nucleosides, the formed ribonucleoside can optionally be protected by methods well known to those skilled in the art, as taught by Greene et al. Protective Groups in Organic Synthesis, John Wiley and Sons, Second Edition, 1991, and then the 2'- OH can be reduced with a suitable reducing agent. Optionally, the 2'-hydroxyl can be activated to facilitate reduction; i. e. via the Barton reduction.
Scheme 2 HO R'O 6 RO Optional 1/O'O 1) R-M O O-LG' 6 l Protection 2) Optional oR2 oR3 Activation 1) Coupling 2) Optional Deprotection If , BASE 1) Optional BASE Protection ------ ! R6 2) Optional R6 reduction OH OH Optional Deprotection V BASE HO O R6 OH
In addition, the L-enantiomers corresponding to the compounds of the invention can be prepared following the same general methods (1 or 2), beginning with the corresponding L-sugar or nucleoside L-enantiomer as starting material.
B. General Svnthesis of 2'-C-Branched Nucheosides 2'-C-Branched ribonucleosides of the following structure:
wherein BASE is a purine or pyrimidine base as defined herein; R7 and R9 are independently hydrogen, OR2, hydroxy, alkyl (including lower alkyl), azido, cyano, alkenyl, alkynyl, Br-vinyl,-C (O) O (alkyl),-C (O) O (lower alkyl),-O (acyl),-O (lower acyl),-O (alkyl),-O (lower alkyl),-O (alkenyl), chlorine, bromine, iodine, NO2, NH2, -NH (lower alkyl),-NH (acyl),-N (lower alkyl) 2,-N (acyl) 2; Rl° is H, alkyl (including lower alkyl), chlorine, bromine or iodine;
alternatively, R7 and R9, or R7 and Rl° can come together to form a pi bond; R'and R2 are independently H; phosphate (including monophosphate, diphosphate, triphosphate, or a stabilized phosphate prodrug); acyl (including lower acyl) ; alkyl (including lower alkyl) ; sulfonate ester including alkyl or arylalkyl sulfonyl including methanesulfonyl and benzyl, wherein the phenyl group is optionally substituted with one or more substituents as described in the definition of aryl given herein; a lipid, including a phospholipid ; an amino acid; a carbohydrate; a peptide; cholesterol; or other pharmaceutically acceptable leaving group which when administered in vivo is capable of providing a compound wherein R'or R2 is independently H or phosphate; R6 is an alkyl, chloro-, bromo-, fluoro-, iodo-alkyl (i. e. CF3), alkenyl, or alkynyl (i. e. allyl) ; and X is O, S, SO2 or CH2 can be prepared by one of the following general methods.
1. Glycosylation of the nucleobase with an appropriately modified sugar The key starting material for this process is an appropriately substituted sugar with a 2'-OH and 2'-H, with the appropriate leaving group (LG), for example an acyl group or a chloro, bromo, fluoro or iodo. The sugar can be purchased or can be prepared by any known means including standard epimerization, substitution, oxidation and reduction techniques.
The substituted sugar can then be oxidized with the appropriate oxidizing agent in a compatible solvent at a suitable temperature to yield the 2'-modified sugar. Possible oxidizing agents are Jones reagent (a mixture of chromic acid and sulfuric acid), Collins's reagent (dipyridine Cr (VI) oxide, Corey's reagent (pyridinium chlorochromate), pyridinium dichromate, acid dichromate, potassium permanganate, Mn02, ruthenium tetroxide, phase transfer catalysts such as chromic acid or permanganate supported on a polymer, Cl2- pyridine, H202-ammonium molybdate, NaBrO2-CAN, NaOCI in HOAc, copper chromite, copper oxide, Raney nickel, palladium acetate, Meerwin-Pondorf-Verley reagent (aluminum t-butoxid with another ketone) and N-bromosuccinimide.
Then coupling of an organometallic carbon nucleophile, such as a Grignard reagent, an organolithium, lithium dialkylcopper or R6-SiMe3 in TBAF with the ketone with the appropriate non-protic solvent at a suitable temperature, yields the 2'-alkylated sugar. The
alkylated sugar can be optionally protected with a suitable protecting group, preferably with an acyl or silyl group, by methods well known to those skilled in the art, as taught by Greene et al. Protective Groups in Organic Synthesis, John Wiley and Sons, Second Edition, 1991.
The optionally protected sugar can then be coupled to the BASE by methods well known to those skilled in the art, as taught by Townsend Chemistry of Nucleosides and Nucleotides, Plenum Press, 1994. For example, an acylated sugar can be coupled to a silylated base with a Lewis acid, such as tin tetrachloride, titanium tetrachloride or trimethylsilyltriflate in the appropriate solvent at a suitable temperature. Alternatively, a halo-sugar can be coupled to a silylated base with the presence of trimethylsilyltriflate.
Subsequently, the nucleoside can be deprotected by methods well known to those skilled in the art, as taught by Greene et al. Protective Groups in Organic Synthesis, John Wiley and Sons, Second Edition, 1991.
In a particular embodiment, the 2'-C-branched ribonucleoside is desired. The synthesis of a ribonucleoside is shown in Scheme 3. Alternatively, deoxyribo-nucleoside is desired. To obtain these nucleosides, the formed ribonucleoside can optionally be protected by methods well known to those skilled in the art, as taught by Greene et al. Protective Groups in Organic Synthesis, John Wiley and Sons, Second Edition, 1991, and then the 2'- OH can be reduced with a suitable reducing agent. Optionally, the 2'-hydroxyl can be activated to facilitate reduction; i. e. via the Barton reduction.
Scheme 3 HO HO 6 RO Rs \LG Dxidation \LG 1) R-M _p LG Oxidation LG 0. OH OH 2) Optional t Protection 1) Coupling 2) Optional Deprotection If BASE 1) Optional BASE Protection . _________________ O oR2 2) Optional OH OH Reduction Optional Deprotection t BASE HO OH
2. Modification of a pre-formed nucleoside The key starting material for this process is an appropriately substituted nucleoside with a 2'-OH and 2'-H. The nucleoside can be purchased or can be prepared by any known means including standard coupling techniques. The nucleoside can be optionally protected with suitable protecting groups, preferably with acyl or silyl groups, by methods well known to those skilled in the art, as taught by Greene et al. Protective Groups in Organic Synthesis, John Wiley and Sons, Second Edition, 1991.
The appropriately protected nucleoside can then be oxidized with the appropriate oxidizing agent in a compatible solvent at a suitable temperature to yield the 2'-modified sugar. Possible oxidizing agents are Jones reagent (a mixture of chromic acid and sulfuric acid), Collins's reagent (dipyridine Cr (VI) oxide, Corey's reagent (pyridinium chlorochromate), pyridinium dichromate, acid dichromate, potassium permanganate, Mn02, ruthenium tetroxide, phase transfer catalysts such as chromic acid or permanganate supported on a polymer, Cl2-pyridine, H202-ammonium molybdate, NaBr02-CAN, NaOCI in HOAc,
copper chromite, copper oxide, Raney nickel, palladium acetate, Meerwin-Pondorf-Verley reagent (aluminum t-butoxid with another ketone) and N-bromosuccinimide.
Subsequently, the nucleoside can be deprotected by methods well known to those skilled in the art, as taught by GreeneGreene et al. Protective Groups in Organic Synthesis, John Wiley and Sons, Second Edition, 1991.
In a particular embodiment, the 2'-C-branched ribonucleoside is desired. The synthesis of a ribonucleoside is shown in Scheme 4. Alternatively, deoxyribo-nucleoside is desired. To obtain these nucleosides, the formed ribonucleoside can optionally be protected by methods well known to those skilled in the art, as taught by Greene et al. Protective Groups in Organic Synthesis, John Wiley and Sons, Second Edition, 1991, and then the 2'- OH can be reduced with a suitable reducing agent. Optionally, the 2'-hydroxyl can be activated to facilitate reduction ; i. e. via the Barton reduction.
Scheme 4 BASE BASE BASE BASE BASE BASE R O Rs O Protection p R6-M O, - OH OH 2) Oxidation ORz O ORS OH Optionat Optional Deprotection BASE 1) Optional BASE Protection t. _________________ OF 2) Optional OH OH Reduction Optional Deprotection BASE BASE 0 OH OH
3. Synthesis Of D-2'-C-Methyl-Ribofuranosyl Cytidine-3'-0-L-Valine Ester
In one synthesis method, depicted in Figure 5, the synthesis comprises reacting cytosine, BSA and SnC4/acetonitrile with 1, 2,3, 5-tetra-O-benzoyl-2-C-methyl-ß-D- ribofuranose (Figure 5, compound 1) to form 4-amino-l- (3, 4-dibenzoyloxy-5- benzoyloxymethyl-3-methyl-tetrahydro-furan-2-yl)-IH-pyrimidi n-2-one (Figure 5, compound 2 ; and reacting (Figure 5, compound 2) with NaOMe/MeOH to provide 4-amino- <BR> <BR> <BR> 1-(3, 4-dihydroxy-5-hydroxymethyl-3-methyl-tetrahydro-furan-2-yl)- lH-pyrimidin-2-one (Figure 5, compound ), also known as 2-C-methyl-P-D-ribofuranose. The use of cytosine as a starting material rather than benzoyl-cytosine improves the"atom economy"of the process and simplifies purification at later steps.
The next steps in this process comprise reacting (Figure 5, compound ) with Me2NCH (OMe) 2 in DMF to form (Figure 5, compound dz N [1- (3, 4-dihydroxy-5- hydroxymethyl-3-methyl-tetrahydro-furan-2-yl)-2-oxo-1, 2-dihydro-pyrimidin-4-yl]-N,N- dimethyl-formamidine, which is the amino-protected form of (Figure 5, compound O ; reacting (Figure 5, compound 4) with TBDPSCI and imidazole in DCM to provide the 5'- silyl-protected form of (Figure 5, compound 4) as N'- {1- [5- (tert-butyl-diphenyl- silanyloxymethyl)-3, 4-dihydroxy-3-methyl-tetrahydro-furan-2-yl] -2-oxo-1,2-dihydro- pyrimidin-4-yl}-N, N-dimethyl-formamidine (Figure 5, compound ), where the use of DCM provides the advantage of having greater control over disilyl by-product formation; reacting (Figure 5, compound 2 with N-Boc-L-valine, EDC and DMAP in DCM at room temperature to form 2-tert-butoxycarbonylamino-3-methyl-butyric acid 2-(tert-butyl-diphenyl-silanyloxy- methyl)-5-[4-(dimethylamino-methyleneamino)-2-oxo-2H-pyrimid in-1-yl]-4-hydroxy-4- methyl-tetrahydro-furan-3-yl ester (Figure 5, compound @ ; removing the silyl and amino- protecting groups by reacting (Figure 5, compound @ with NH4F in MeOH in the presence of approximately 10 mole equivalents of ethyl acetate to prevent cleavage of the 3'-O-valinyl ester by liberated ammonia, and refluxing the mixture to provide 2-tert- butoxycarbonylamino-3-methyl-butyric acid 5-(4-amino-2-oxo-2H-pyrimidin-l-yl)-4- hydroxy-2-hydroxymethyl-4-methyl-tetrahydro-furan-3-yl ester to provide (Figure 5, compound 2 ; and finally, reacting (Figure 5, compound 2 with HCl in EtOH to provide 2- amino-3-methyl-butyric acid 5- (4-amino-2-oxo-2H-pyrimidin-1-yl)-4-hydroxy-2- hydroxymethyl-4-methyl-tetrahydro-furan-3-yl ester, dihydrochloride salt (Figure 5, compound S as a final product.
6. Alternative Synthesis of D-2'-C-Methyl-Ribofuranosyl Cytidine-3'-O-L-Valine Ester In another method to synthesize the compounds of the invention, shown in Figure 6, benzoylcytosine, BSA and SnC14/acetonitrile are reacted with 1, 2,3, 5-tetra-O-benzoyl-2-C- methyl-o-D-ribofuranose (Figure 6, compound la) to form 4-benzoylamino-1- (3, 4- dibenzoyloxy-5-benzoyloxymethyl-3-methyl-tetrahydro-furan-2- yl)-1H-pyrimidin-2-one (Figure 6, compound) ; reacting (Figure 6, compound) with NH3 in methanol and chromatographically separating the product, 4-amino-1-(3,4-dihydroxy-5-hydroxymethyl-3- methyl-tetrahydro-furan-2-yl)-1H-pyrimidin-2-one (Figure 6, compound), also known as ß-D-2'-C-methyl-cytidine ; reacting (Figure 6, compound) with Me2NCH (OMe) 2 in DMF at room temperature for 1.5 hours to form N [1- (3, 4-dihydroxy-5-hydroxymethyl-3-methyl- tetrahydro-furan-2-yl)-2-oxo-1, 2-dihydro-pyrimidin-4-yl]-N, N-dimethyl-formamidine (Figure 6, compound) ; reacting (Figure 6, compound) with TBDPSCI and pyridine at room temperature for 6 hours to provide N'-{1-[5-(tert-butyl-diphenyl-silanyloxymethyl)-3, 4- dihydroxy-3-methyl-tetrahydro-furan-2-yl]-2-oxo-1, 2-dihydro-pyrimidin-4-yl}-N, N- dimethyl-formamidine (Figure 6, compound Sa ; reacting (Figure 6, compound) with N Boc-L-valine, DEC and DMAP in THF/DMF at room temperature for 2 days and subjecting the product formed from this reaction to HPLC in order to provide 2-tert- butoxycarbonylamino-3-methyl-butyric acid 2- (tert-butyl-diphenyl-silanyloxy-methyl)-5- [4- <BR> <BR> <BR> (dimethylaminomethyleneamino)-2-oxo-2H-pyrimidin-1-yl]-4-hyd roxy-4-methyl-tetrahydro- furan-3-yl ester (Figure 6, compound 6a) ; refluxing (Figure 6, compound La) with NH4F in MeOH for about 3 hours to remove the silyl and amino-protecting groups, and subjecting the product to chromatographic purification to provide 2-tert-butoxycarbonylamino-3-methyl- butyric acid 5-(4-amino-2-oxo-2H-pyrimidin-1-yl)-4-hydroxy-2-hydroxymethy l-4-methyl- tetrahydro-furan-3-yl ester (Figure 6, compound) ; and finally reacting (Figure 6, compound) with HCl in EtOAc at room temperature to provide 2-amino-3-methyl-butyric acid 5- (4-amino-2-oxo-2H-pyrimidin-1-yl)-4-hydroxy-2-hydroxymethyl- 4-methyl- tetrahydro-furan-3-yl ester, dihydrochloride salt (Figure 6, compound) as a final product.
The synthesis of 2'-C-methyl-cytidine-3'-O-L-valine ester (val-mcyd) is depicted in scheme 5 and scheme 6, and described below.
Scheme 5 STEP STEP 1 2 O HO Bz0 O OH O 0 C6HSCOCI/TEA--0 HO". OH C DMAP/DME'' water = = Bz0 OBz OH HO OH 10 D-Fructose Bozo bozo Red-AI/EtOH O OBz ^^OH C6H5COCUTEA toluène toluene BzÒ OBz DMAP/DME s STEP STEP 4 3 1l 4 12
Step 1: Synthesis of scheme 5, compound 9: 2-C-Methyl-D-ribonic-y-lactone De-ionized water (100 mL) was stirred in a 250 mL 3-necked round bottom flask, equipped with an overhead stirrer, a stirring shaft, a digital temperature read-out device and an argon line. Argon was bubbled into water for thirty minutes and D-fructose (20.0 g, 0.111 mole) was added and the solution became clear in a few minutes. Calcium oxide (12.5 g, 0.223 mole) was added in portions over a period of five minutes and the mixture was vigorously stirred. An exotherm was observed and reaction temperature reached 39. 6°C after 10 minutes from the start of the calcium oxide addition. After about fifteen minutes, the reaction mixture developed a yellow color that deepened with time. After three hours, an aliquot was withdrawn for TLC analysis. The aliquot was acidified to pH 2 using saturated aqueous solution of oxalic acid. The resulting white suspension was evaporated under reduced pressure to remove the water. Toluene (2 mL) was added to the residue and the mixture was evaporated under reduced pressure (at 45-50°C) to remove any trace of water.
The residual solid was re-constituted in 2 mL of 1: 1 tetrahydrofuran: methanol mixture.
After thorough mixing, the suspension was allowed to settle and the supernatant clear solution was spotted for TLC (silica plate was developed in 2% methanol in ethyl acetate and
stained in 1% alkaline potassium permanganate dip. The plate was then heated, using a heat gun, until the appearance of yellowish spots on the pink background). The desired lactone typically appears at an Rf value of 0.33 under the above conditions. More polar by-products and unreacted material are detected in the Rf value range of 0.0 to 0.2.
Although product formation was observed after 3 hours, the reaction was allowed to continue for 22 hours during which time the reaction mixture was stirred at 25 °C. At the end of this period, pH of the mixture was 13.06. Carbon dioxide gas was bubbled into the reaction mixture for about 2.5 hours (pH was 7.25). The formed calcium carbonate solid was removed by vacuum filtration, filter cake washed with 50 mL of de-ionized water. The aqueous layers were combined and treated with oxalic acid (5.0 g, 0.056 mole) and the mixture was vigorously stirred at 25°C for 30 minutes (The initial dark color largely disappeared and the mixture turned into a milky white slurry). The pH of the mixture at this stage is typically 2-3.
The slurry mixture was stirred at 45-50°C overnight. The mixture was then evaporated under reduced pressure and at 45-50°C to remove 75 mL of water. Sodium chloride (30 g) and tetrahydrofuran (100 mL) were added to the aqueous slurry (about 75 mL) and the mixture was vigorously stirred at 25°C for 30 minutes. The layers were separated and the aqueous layer was stirred for 10 minutes with 75 mL of fresh tetrahydrofuran. This process was repeated for three times and the tetrahydrofuran solutions were combined and stirred with 10 g of anhydrous magnesium sulfate for 30 minutes. The mixture was filtered and the magnesium sulfate filter cake was washed with 60 mL of tetrahydrofuran. The filtrate was evaporated under reduced pressure and at 40°C to give 10.86 g of crude product as a dark orange semisolid. (For scale up runs tetrahydrofuran will be replaced with acetone instead of evaporation of crude product to dryness). Crude product was stirred with acetone (20 mL) at 20°C for 3 hours. Product was collected by vacuum filtration and the filter cake washed with 12 mL of acetone to give the desired product 9 as white crystalline solid. Product was dried in vacuum to give 2.45 g (13.6% yield). Melting point of compound 9: 158-162°C (literature melting point: 160-161 °C).'H NMR (DMSO-d6) 8 ppm 5.69 (s, 1H, exch. With D20), 5.41 (d, 1H, exch. With D20), 5.00 (t, 1H, exch. With D20), 4.15 (m, 1H), 3.73 (m, 2H), 3.52 (m, 1H), 1.22 (s, 3H). I3C NMR (DMSO-d6) 8 ppm 176.44, 82.95, 72.17, 72.02, 59.63, 20.95.
(C6H, 005 : calcd C, 44.45 ; H, 6.22. Found: C, 44.34 ; H, 6.30).
Step 2: Synthesis of scheme 5. compound 10: 2, 3, 5-Tri-O-benzoyl-2-C-methyl-D-ribonic-y- lactone A mixture of lactone 1 (3.0 g, 18.50 mmol. ), 4-dimethylaminopyridine (0.45 g, 3.72 mmol.) and triethylamine (25.27 g, 249.72 mmol. ) in 1,2-dimethoxy ethane (50 mL) was stirred at 25°C under argon atmosphere for thirty minutes. This white suspension was cooled to 5°C and benzoyl chloride (11.7 g, 83.23 mmol. ) was added over a period of fifteen minutes. The mixture was stirred at 25°C for two hours. TLC analysis (silica, 2% methanol in ethyl acetate) indicated complete consumption of starting material. Ice cold water (100 g) was added to the reaction mixture and stirring was continued for thirty minutes. The formed white solids were collected by vacuum filtration and filter cake washed with cold water (50 mL).
This crude product was stirred with tert-butyl methyl ether (60 mL) at 20 °C for thirty minutes, then filtered, filter cake washed with tert-butyl methyl ether (25 mL) and dried in vacuum to give 7.33 g (83.4% yield) of compound 10 as a white solid in 97.74% purity (HPLC/AUC). Melting point of compound 10: 137-140 °C (literature melting point: 141-142 °C).'H NMR (CDCI3) 6 ppm 8.04 (d, 2H), 7.92 (d, 2H), 7.73 (d, 2H), 7.59 (t, 1H), 7.45 (m, 4H), 7.32 (t, 2H), 7.17 (t, 2H), 5.51 (d, 1H), 5.17 (m, 1H), 4.82-4. 66 (d of an AB quartet, 2H) 1.95, (s, 3H). 13C NMR (CDC13) 8 ppm 172.87, 166.17, 166.08, 165.58, 134.06, 133.91, 133.72, 130.09, 129.85, 129.80, 129.37, 128.78, 128.60, 128.49, 127.96, 127.89, 79.67, 75.49, 72.60, 63.29, 23.80. TOF MS ES+ (M+1 : 475).
Step 3: Synthesis of scheme 5, compound 11: 2, 3. 5-Tri-O-benzovl-2-C-methvl--D- ribofuranose: A solution of Red-Al (65wt. % in toluene, 2.0 mL, 6.56 mmol. ) in anhydrous toluene (2.0 mL) was stirred at 0°C under argon atmosphere. A solution of anhydrous ethanol (0.38 mL, 6.56 mmol. ) in anhydrous toluene (1.6 mL) was added to the toluene solution over a period of five minutes. The resulting mixture was stirred at 0 °C for fifteen minutes and 2 mL (2.18 mmol. ) of this Red-Al/ethanol reagent was added to a cold (-5°C) solution of 2, 3,5-tri- O-benzoyl-2-C-methyl-D-ribonolactone (475 mg, 1.0 mmol. ) in anhydrous toluene (10 mL) over a period of 10 minutes. The reaction mixture was stirred at-5 °C for forty minutes. TLC analysis (silica plates, 35% ethyl acetate in heptane) indicated complete consumption of starting material. HPLC analysis indicated only 0. 1% of starting material remaining. The reaction was quenched with acetone (0.2 mL), water (15 mL) and 1 N HCl (15 mL) at 0 °C and allowed to warm to room temperature. 1 N HCl (5 mL) was added to dissolve the inorganic salts (pH: 2-3). The mixture was extracted with ethyl acetate (3 x 25 mL) and the
organic solution washed with brine (25 mL), dried (anhydrous sodium sulfate, 10 g) and solvent removed under reduced pressure and at temperature of 40°C to give the desired product 11 in quantitative yield (480 mg). This material was used as is for the subsequent step.
Step 4: Synthesis of scheme 5. compound 12: 1, 2, 3, 5-tetra-O-benzovI-2-C-methyl-ß-D- ribofuranose: Benzoyl chloride (283 mg, 2.0 mmol. ) was added, over a period of five minutes, to a cold solution (5°C) of compound 11 (480 mg, 1.0 mmol.), 4-dimethylaminopyridine (12.3 mg, 0.1 mmol. ) and triethylamine (506 mg, 5.0 mmol. ) in anhydrous tetrahydrofuran (5 mL).
The reaction mixture was stirred at room temperature and under argon atmosphere overnight.
HPLC analysis indicated 0.25% of un-reacted starting material. The reaction was quenched by adding ice-cold water (10 g) and saturated aqueous solution of sodium bicarbonate.
Tetrahydrofuran was removed under reduced pressure and the mixture was extracted with ethyl acetate (50 mL). The organic solution was washed with water (25 mL), brine (25 mL), dried (anhydrous sodium sulfate, 12 g) and solvent removed under reduced pressure to give 650 mg of thick oily product. This crude product was stirred with 5 mL of tert-butyl methyl ether for 5 minutes and heptane (5 mL) and water (0.1 mL) were added and stirring was continued for an additional period of two hours at 20°C. Solids were collected by vacuum filtration and filter caked washed with 1: 1 heptane : tert-butyl methyl ether solution (6 mL) and tert-butyl methyl ether (2 mL). Drying the solid in vacuum gave 300 mg (52%) of desired product 12 (98.43% pure by HPLC/AUC) as a white solid that melted at 154-156. 3°C (literature melting point: 155-156°C).'H NMR (CDC13) 8 ppm 8.13 (m, 4H), 8.07 (d, 2H), 7.89 (d, 2H), 7.63 (m, 3H), 7.48 (m, 6H), 7.15 (m, 3H), 7.06 (s, 1H), 5.86 (dd, 1H), 4.79 (m, 1H), 4.70-4. 52 (d of an AB quartet, 2H), 1.95, (s, 3H). I3C NMR (CDCI3) 8 ppm 166. 31, 165.83, 165.01, 164.77, 134.01, 133.86, 133.70, 133. 17, 130.44, 130.13, 129.97, 129.81, 129.59, 129.39, 129.07, 128.84, 128.76, 128.37, 98.01, 86.87, 78.77, 76.35, 64.05, 17.07.
(C34H2809 : calcd C, 70.34 ; H, 4.86. Found: C, 70.20 ; H, 4.95).
Scheme 6 NH2 NH2 NH2 STEP N STEP 5 jan bozo ' Cytosine/BSA NaOMe/MoOH HO N SnClylAcN \OBzlO/Bz OH OH 12 13 mCvd NH2 NH3 CI STEP'N STEP i 8 N ho , BOCValine/CDI HCI/EtOH -.-p/ DMAPlTEAIDMF O OH O O O O OH NHY Cl NH CI NH3 14 val-mCvd
Step 5: Synthesis of scheme 6, compound 13: 4-Amino-1-(3q4-dibenzoeloxv-5- benzyloxymethyl-3-methyl-tetrahydro-furan-2-yl)-pyrimidine-2 -one Cytosine (89 g, 0.80 mol) was suspended in acetonitrile (900 mi) in a 12 L round bottomed flask equipped with a reflux condenser, overhead stirrer and an argon inlet adapter.
The suspension was stirred at 20°C under argon atmosphere and N, O- bis (trimethylsilyl) acetamide (537 ml, 2.2 mol) was added in one portion. The resulting solution was heated to 80° C and stirred for an additional hour at the same temperature.
1, 2,3, 5-tetra-O-benzoyl-2-C-methyl-0-D-ribofuranose (425.0 g, 0.73 mol) was suspended in acetonitrile (4000 ml) and added to the reaction mixture. The reaction mixture became clear after a few minutes and the temperature dropped to ca. 50° C. Tin (IV) chloride (154 mi, 1.31 mol) was added over a period of 15 minutes and stirring was continued at 80°C. After one hour, an aliquot of reaction mixture was quenched by adding aqueous sodium bicarbonate solution and extracting the aqueous layer with ethyl acetate. The ethyl acetate layer was examined by TLC (silica gel, 20% ethyl acetate in heptane, Rf for sugar derivative: 0.40).
TLC analysis indicated the complete consumption of the sugar derivative. Desired product was detected by TLC using 10% methanol in dichloromethane (Rf: 0.37). The reaction was also monitored by HPLC (Method # 2). Reaction mixture was cooled to 20°C and quenched by adding saturated aqueous sodium bicarbonate solution (3000 ml) over a period of 30 minutes (observed an exotherm when added the first few drops of the sodium bicarbonate solution). Solid sodium bicarbonate (1350 g) was added in portions to avoid foaming. The mixture was checked to make sure that its pH is > 7. Agitation was stopped and layers were
allowed to separate for 20 minutes. The aqueous layer was drained and stirred with ethyl acetate (1500 ml) and the mixture was allowed to separate (30 minutes). The organic layer was isolated and combined with the acetonitrile solution. The organic solution was washed with brine (500 ml) and then solvent stripped to a volume of ca. 750 ml. Product can be used as is in the subsequent reaction. It may also be further stripped to white foamy solid, in quantitative yield. Structure of compound 13 was confirmed by IH NMR analysis.
Step 6: Synthesis of scheme 6, compound mCyd : 4-Amino-1-(3*4-dihydroxe-5- hydroxymethyl-3-methyl-tetrahydro-furan-2-yl)-1H-pyrimidine- 2-one Sodium methoxide (13.8 g, 0.26 mol) was added to a solution of compound 10 (416 g, 0. 73mol) in methanol (2000 ml). The reaction mixture was stirred at room temperature and monitored by TLC (silica gel, 10% methanol in dichloromethane, Rf of compound 9: 0.53) and (silica gel, 30% methanol in dichloromethane, Rf of compound 11: 0.21). Product started to precipitate after 30 minutes and TLC indicated reaction completion after two hours. The reaction was also monitored by HPLC (Method # 2). Methanol was removed under reduced pressure to a volume of ca. 500 ml chased with ethanol (2 x 500 ml) to a volume of ca. 500 ml. The residual thick slurry was diluted with 750 ml of ethanol and the mixture was stirred at 20 ° C for one hour. Product was collected by filtration, filter cake washed with ethanol (100 ml) and tert-butyl-methyl ether (100 ml) and dried to give 168 g (90% yield for the two steps) of product 11 in purity of > 97% (HPLC/AUC). Product was also analyzed by IH and 13C NMR.
Step 7: Synthesis of scheme 6, compound 14: 2-Tert-butoxycarbonylamino-3-methyl- butyric acid 5-(4-amino-2-oXo-2H-pyrimidin-l-yl !-4-hydroxy-2-hvdroxymethyl-4-meth tetrahydro-furan-3-yl ester A solution of N- (tert-butoxycarbonyl)-L-valine (46.50 g, 214 mmol.), carbonyldiimidazole (34.70 g, 214 mmol.), and anhydrous tetrahydrofuran (1000 mL) in a 2 L round bottom flask, was stirred at 25°C under argon for 1.5 hours and then at 40-50°C for 20 minutes. In a separate 5 L 5-necked round bottom flask, equipped with an overhead stirrer, cooling tower, temperature probe, addition funnel, and an argon line was added 4- <BR> <BR> <BR> amino-1-(3, 4-dihydroxy-5-hydroxymethyl-3-methyl-tetrahydro-furan-2-yl)- lH-pyrimidine-2- one (50.0 g, 195 mmol. ) and anhydrous N, N-dimethylformamide (1000 mL). This mixture was heated at 100°C for 20 minutes until all of the pyrimidine-2-one derivative compound went into solution, and then triethyl amine (500 mL) and 4-dimethylaminopyridine (2.38 g,
19 mmol) were added to the solution. The mixture was next heated at 97° C for 20 minutes and the tetrahydrofuran solution was added slowly through an addition funnel over a period of 2 hours, maintaining the temperature no lower than 82°C. The reaction mixture was heated at 82 °C for 1 hour and monitored by HPLC (product = 68%, SM = 11 %, and impurity at about 12 min = 17%, excluding dimethylaminopyridine). The reaction mixture was cooled to room temperature and then triethylamine and tetrahydrofuran were removed under vacuum at 30°C. The solution was then neutralized with acetic acid to a pH of 7.69. N, N- dimethylformamidine was removed under vacuum at 35°C and chased with ethyl acetate (2 x 200 mL). The crude product was stirred with ethyl acetate (500 mL) and water (300 mL).
The two layers were separated and the aqueous layer was extracted with ethyl acetate (500 mL). The combined organic layers were washed with an aqueous saturated brine solution (500 mL). Next the organic layer was extracted with an aqueous solution of malonic acid (4 x 400 mL, 10wt. %). The organic layer was checked by TLC (silica, 20% methanol in dichloromethane) to make sure that all the desired product was removed from the organic layer. The acidic aqueous extracts were combined and cooled in an ice bath and neutralized with triethylamine to a pH of 7.40 so that the solids fell out of solution. Ethyl acetate then was added to the aqueous layer. The white solids were collected by vacuum filtration.
Drying the obtained solids in vacuum gave 81.08 g of 99.01 pure (HPLC) first crop.
Step 8: Synthesis of scheme 6, val-mCyd-2-Amino-3-methyl-butyric acid 5- (4-amino-2- <BR> <BR> <BR> oxo-2H-pyrimidine-1-yl)-4-hydroxy-2 hydroxy-methyl-4-methyl-tetrahydro-furan-3-yl ester (dihydrochloride salt) A solution of compound 14 (21.0 g, 0.046 mol) in ethanol (168 ml) was stirred in a round bottomed flask equipped with an overhead stirrer, temperature probe, argon line and hydrogen chloride gas bubbler. Hydrogen chloride gas (22 g) was bubbled into the clear solution over a period of one hour. The reaction temperature was kept below 30°C using an ice-water bath. Solid formation started after a few minutes of introducing the hydrogen chloride gas. After 4 hours, HPLC (method # 3) showed only 0.8% of starting material.
Solids were collected by filtration and filter cake washed with ethanol (20 ml) and di-ethyl ether (100 ml). After drying product under vacuum for 16 hours, 19.06 g (96.5%) of val- mCyd was obtained in 97.26% purity (HPLC, method # 3); m. p. 210°C (brown), 248-250°C (melted) ;'H NMR (DMSO-d6) 8 ppm 10.0 (s, 1H, 1/2NH2, D20 exchangeable), 8.9-8. 6 (2 br s, 4H, 1/2NH2, NH3, D20 exchangeable), 8.42 (d, 1H, H-6, J 5-6= 7.9 Hz), 6.24 (d, 1H, H-5, J5-6= 7.9 Hz), 5.84 (s, 1H, H-1'), 5.12 (d, 1H, H-3', J3 1 = 8.8 Hz), 4.22 (d, 1H, H-4, J3-4=
8.7 Hz), 4.0-3. 9 (m, IH, CH), 3.8-3. 5 (m, 2H, H-5', H-5"), 2.3-2. 1 (m, 1H, CH), 1.16 (s, 3H, CH3), 1.0 (m, 6H, (CH3) 2CH); FAB>0 (GT) 713 (2M+H) +, 449 (M+G+H) +, 357 (M+H) +, 246 (S) +, 112 (B+2H) + ; FAB<0 (GT) 747 (2M+Cl)-, 483 (M+G+C1)', 391 (M+CI)-, 355 (M-H)-, 116 (Val)-, 110 (B)-, 35 (Cl).
Two different HPLC methods were used to analyze the above compounds. Both methods use the following reverse phase column. In method 1, the column was run at a flow rate of 1.00 ml/min of an acetonitrile/water linear gradient for a 20 minute run time. Five- minute equilibration was allowed between runs. The measurements were at 254 nm.
Table A: Retention time of key intermediates: Scheme 5, Compound Retention Time Compund 10 10. 2 min Compund 11 9.4 min Compund 12 12. 9 min
In the second method, identification was determined at 272 nm. A Waters Novapak C18, 3.9 x 150 mm ID, 4p. m particle size, 60A pore size or equivalent can be used. The chromatographic conditions are as follows: injection volume = loll, column temperature = 25°C, flow rate = 1.00 ml/min, ultraviolet detector at 272 nm, run time is 35 minutes. The system suitability requirement for the percent relative standard deviation for the reference standard is not more than 1.0%.
Table B: Purity and impurities are determined at 272 nm Solvent A-20nM Solvent B- triethylammonium Acetonitrile, Time (minutes) acetate buffer HPLC grade. 0.00 100.0 0.0 10. 00 85. 0 15. 0 25. 00 5. 0 95. 0 35. 0 5. 0 95. 0
Table C: Retention times of key intermediates and final drug substance Scheme 6, Compound Retention Time (minutes) Compound mCyd 2.7-2. 8 Compund 14 15.5 val-mCyd 9.1
A process of synthesizing a ß-D-2'-C-methyl-2'-acetyl-ribofuransyl-cytidine-3'-O-L- valine ester is detailed in Figure 7. A process of synthesizing a ß-D-2'-C-methyl-2'-acetyl- ribofuransyl-cytidine-3'-O-L-proline ester is detailed in Figure 8. A process for synthesizing a P-D-2'-C-methyl-2'-acetyl-ribofuransyl-cytidine-3'-O-L-alani ne ester is depicted in Figure 9. A process of synthesizing a ß-D-2'-C-methyl-2'-(cyclohexane carboxylate)-ribofuransyl- cytidine-3'-O-L-valine ester is depicted in Figure 10. These processes can be accomplished using techniques similar to those described above.
C. General Synthesis of 3'-C-Branched Nucleosides 3'-C-Branched ribonucleosides of the following structure: wherein BASE is a purine or pyrimidine base as defined herein; R7 and R9 are independently hydrogen, OR2, hydroxy, alkyl (including lower alkyl), azido, cyano, alkenyl, alkynyl, Br-vinyl,-C (O) O (alkyl),-C (O) O (lower alkyl),-O (acyl),-O (lower acyl),-O (alkyl),-O (lower alkyl),-O (alkenyl), chlorine, bromine, iodine, NO2, NH2, -NH (lower alkyl),-NH (acyl),-N (lower alkyl) 2, -N (acyl)2 ; R8 is H, alkyl (including lower alkyl), chlorine, bromine or iodine; alternatively, R7 and R9, or R8 and R9 can come together to form a pi bond;
R'and R2 are independently H; phosphate (including monophosphate, diphosphate, triphosphate, or a stabilized phosphate prodrug); acyl (including lower acyl) ; alkyl (including lower alkyl) ; sulfonate ester including alkyl or arylalkyl sulfonyl including methanesulfonyl and benzyl, wherein the phenyl group is optionally substituted with one or more substituents as described in the definition of aryl given herein; a lipid, including a phospholipid; an amino acid; a carbohydrate; a peptide; cholesterol; or other pharmaceutically acceptable leaving group which when administered in vivo is capable of providing a compound wherein R'or R2 is independently H or phosphate; R6 is an alkyl, chloro-, fluoro-, bromo-, iodo-alkyl (i. e. CF3), alkenyl, or alkynyl (i. e. allyl) ; and X is O, S, SO2 or CH2 can be prepared by one of the following general methods.
1. Glycosylation of the nucleobase with an appropriately modified sugar The key starting material for this process is an appropriately substituted sugar with a 3'-OH and 3'-H, with the appropriate leaving group (LG), for example an acyl group or a chloro, bromo, fluoro, iodo. The sugar can be purchased or can be prepared by any known means including standard epimerization, substitution, oxidation and reduction techniques.
The substituted sugar can then be oxidized with the appropriate oxidizing agent in a compatible solvent at a suitable temperature to yield the 3'-modified sugar. Possible oxidizing agents are Jones reagent (a mixture of chromic acid and sulfuric acid), Collins's reagent (dipyridine Cr (VI) oxide, Corey's reagent (pyridinium chlorochromate), pyridinium dichromate, acid dichromate, potassium permanganate, Mn02, ruthenium tetroxide, phase transfer catalysts such as chromic acid or permanganate supported on a polymer, C12- pyridine, H202-ammonium molybdate, NaBr02-CAN, NaOCI in HOAc, copper chromite, copper oxide, Raney nickel, palladium acetate, Meerwin-Pondorf-Verley reagent (aluminum t-butoxid with another ketone) and N-bromosuccinimide.
Then coupling of an organometallic carbon nucleophile, such as a Grignard reagent, an organolithium, lithium dialkylcopper or R6-SiMe3 in TBAF with the ketone with the appropriate non-protic solvent at a suitable temperature, yields the 3'-C-branched sugar. The 3'-C-branched sugar can be optionally protected with a suitable protecting group, preferably with an acyl or silyl group, by methods well known to those skilled in the art, as taught by
Greene et al. Protective Groups in Organic Synthesis, John Wiley and Sons, Second Edition, 1991.
The optionally protected sugar can then be coupled to the BASE by methods well known to those skilled in the art, as taught by Townsend Chemistry of Nucleosides and Nucleotides, Plenum Press, 1994. For example, an acylated sugar can be coupled to a silylated base with a Lewis acid, such as tin tetrachloride, titanium tetrachloride or trimethylsilyltriflate in the appropriate solvent at a suitable temperature. Alternatively, a halo-sugar can be coupled to a silylated base with the presence of trimethylsilyltriflate.
Subsequently, the nucleoside can be deprotected by methods well known to those skilled in the art, as taught by Greene et al. Protective Groups in Organic Synthesis, John Wiley and Sons, Second Edition, 1991.
In a particular embodiment, the 3'-C-branched ribonucleoside is desired. The synthesis of a ribonucleoside is shown in Scheme 7. Alternatively, deoxyribo-nucleoside is desired. To obtain these nucleosides, the formed ribonucleoside can optionally be protected by methods well known to those skilled in the art, as taught by Greene et al. Protective Groups in Organic Synthesis, John Wiley and Sons, Second Edition, 1991, and then the 2'- OH can be reduced with a suitable reducing agent. Optionally, the 2'-hydroxyl can be activated to facilitate reduction; i. e. via the Barton reduction.
Scheme 7 HO I) Optional R10 Rl° R6 WLG Protection WLG 1) R6-M cl ° 2) Oxidation 2) Optional S Protection 1) Coupling 2) Optional Deprotection BASE 1) Optional BASE Protection E _________________ 2) Optional Reduction Optional Deprotection V BASE HO W O OH
2. Modification of a pre-formed nucleoside The key starting material for this process is an appropriately substituted nucleoside with a 3'-OH and 3'-H. The nucleoside can be purchased or can be prepared by any known means including standard coupling techniques. The nucleoside can be optionally protected with suitable protecting groups, preferably with acyl or silyl groups, by methods well known to those skilled in the art, as taught by Greene et al. Protective Groups in Organic Synthesis, John Wiley and Sons, Second Edition, 1991.
The appropriately protected nucleoside can then be oxidized with the appropriate oxidizing agent in a compatible solvent at a suitable temperature to yield the 2'-modified sugar. Possible oxidizing agents are Jones reagent (a mixture of chromic acid and sulfuric acid), Collins's reagent (dipyridine Cr (VI) oxide, Corey's reagent (pyridinium chlorochromate), pyridinium dichromate, acid dichromate, potassium permanganate, MnO2, ruthenium tetroxide, phase transfer catalysts such as chromic acid or permanganate supported on a polymer, 02-pyridine, H202-ammonium molybdate, NaBr02-CAN, NaOCI in HOAc,
copper chromite, copper oxide, Raney nickel, palladium acetate, Meerwin-Pondorf-Verley reagent (aluminum t-butoxid with another ketone) and N-bromosuccinimide.
Subsequently, the nucleoside can be deprotected by methods well known to those skilled in the art, as taught by GreeneGreene et al. Protective Groups in Organic Synthesis, John Wiley and Sons, Second Edition, 1991.
In a particular embodiment, the 3'-C-branched ribonucleoside is desired. The synthesis of a ribonucleoside is shown in Scheme 8. Alternatively, deoxyribo-nucleoside is desired. To obtain these nucleosides, the formed ribonucleoside can optionally be protected by methods well known to those skilled in the art, as taught by Greene et al. Protective Groups in Organic Synthesis, John Wiley and Sons, Second Edition, 1991, and then the 2'- OH can be reduced with a suitable reducing agent. Optionally, the 2'-hydroxyl can be activated to facilitate reduction; i. e. via the Barton reduction.
Scheme 8 sASE sASE sAsE BASE. BASE BASE R O R6 < Protection 0 R-M _o OH 2) Oxidation O OR3 OH OR Optional Deprotection if BASE 1) Optional BASE Protection ___________ oR2 2) Optional OH OH Reduction Optional Deprotection v BASE Holz O OH
In another embodiment of the invention, the L-enantiomers are desired. Therefore, the L-enantiomers can be corresponding to the compounds of the invention can be prepared following the same foregoing general methods, beginning with the corresponding L-sugar or nucleoside L-enantiomer as starting material.
D. General Synthesis of 4'-C-Branched Nucleosides 4'-C-Branched ribonucleosides of the following structure:
wherein BASE is a purine or pyrimidine base as defined herein; R7 and R9 are independently hydrogen, OR2, hydroxy, alkyl (including lower alkyl), azido, cyano, alkenyl, alkynyl, Br-vinyl,-C (O) O (alkyl),-C (O) O (lower alkyl),-O (acyl),-O (lower acyl),-O (alkyl),-O (lower alkyl),-O (alkenyl), chlorine, bromine, iodine, NO2, NH2, -NH(lower alkyl), -NH(acyl), -N(lower alkyl) 2, -N (acyl) 2; R8 and Rlo are independently H, alkyl (including lower alkyl), chlorine, bromine or iodine; alternatively, R7 and R9, R7 and Rl°, R8 and R9, or R8 and R'°can come together to form a pi bond; Rl and R2 are independently H; phosphate (including monophosphate, diphosphate, triphosphate, or a stabilized phosphate prodrug); acyl (including lower acyl) ; alkyl (including lower alkyl) ; sulfonate ester including alkyl or arylalkyl sulfonyl including methanesulfonyl and benzyl, wherein the phenyl group is optionally substituted with one or more substituents as described in the definition of aryl given herein; a lipid, including a phospholipid ; an amino acid; a carbohydrate; a peptide; cholesterol; or other pharmaceutically acceptable leaving group which when administered in vivo is capable of providing a compound wherein R'is independently H or phosphate; R6 is an alkyl, halogeno-alkyl (i. e. CF3), alkenyl, or alkynyl (i. e. allyl) ; and X is O, S, SO2 or CH2 can be prepared by the following general method.
Modification from the pentodialdo-furanose The key starting material for this process is an appropriately substituted pentodialdo- furanose. The pentodialdo-furanose can be purchased or can be prepared by any known means including standard epimerization, substitution and cyclization techniques.
In a preferred embodiment, the pentodialdo-furanose is prepared from the appropriately substituted hexose. The hexose can be purchased or can be prepared by any known means including standard epimerization (e. g. via alkaline treatment), substitution and coupling techniques. The hexose can be either in the furanose form, or cyclized via any means known in the art, such as methodology taught by Townsend Chemistry of Nucleosides and Nucleotides, Plenum Press, 1994, preferably by selectively protecting the hexose, to give the appropriate hexafuranose.
The 4'-hydroxymethylene of the hexafuranose then can be oxidized with the appropriate oxidizing agent in a compatible solvent at a suitable temperature to yield the 4'- aldo-modified sugar. Possible oxidizing agents are Swern reagents, Jones reagent (a mixture of chromic acid and sulfuric acid), Collins's reagent (dipyridine Cr (VI) oxide, Corey's reagent (pyridinium chlorochromate), pyridinium dichromate, acid dichromate, potassium permanganate, Mn02, ruthenium tetroxide, phase transfer catalysts such as chromic acid or permanganate supported on a polymer, Ckpyridine, H202-ammonium molybdate, NaBrO2- CAN, NaOCI in HOAc, copper chromite, copper oxide, Raney nickel, palladium acetate, Meerwin-Pondorf-Verley reagent (aluminum t-butoxid with another ketone) and N bromosuccinimide, though preferably using H3P04, DMSO and DCC in a mixture of benzene/pyridine at room temperature.
Then, the pentodialdo-furanose can be optionally protected with a suitable protecting group, preferably with an acyl or silyl group, by methods well known to those skilled in the art, as taught by Greene et al. Protective Groups in Organic Synthesis, John Wiley and Sons, Second Edition, 1991. In the presence of a base, such as sodium hydroxide, the protected pentodialdo-furanose can then be coupled with a suitable electrophilic alkyl, halogeno-alkyl (i. e. CF3), alkenyl or alkynyl (i. e. allyl), to obtain the 4'-alkylated sugar. Alternatively, the protected pentodialdo-furanose can be coupled with the corresponding carbonyl, such as formaldehyde, in the presence of a base, such as sodium hydroxide, with the appropriate polar solvent, such as dioxane, at a suitable temperature, which can then be reduced with an appropriate reducing agent to give the 4'-alkylated sugar. In one embodiment, the reduction
is carried out using PhOC (S) CI, DMAP, preferably in acetonitrile at room temperature, followed by treatment of ACCN and TMSS refluxed in toluene.
The optionally activated sugar can then be coupled to the BASE by methods well known to those skilled in the art, as taught by Townsend Chemistry of Nucleosides and Nucleotides, Plenum Press, 1994. For example, an acylated sugar can be coupled to a silylated base with a Lewis acid, such as tin tetrachloride, titanium tetrachloride or trimethylsilyltriflate in the appropriate solvent at a suitable temperature.
Subsequently, the nucleoside can be deprotected by methods well known to those skilled in the art, as taught by Greene et al. Protective Groups in Organic Synthesis, John Wiley and Sons, Second Edition, 1991.
In a particular embodiment, the 4'-C-branched ribonucleoside is desired.
Alternatively, deoxyribo-nucleoside is desired. To obtain these deoxyribo-nucleosides, a formed ribo-nucleoside can optionally be protected by methods well known to those skilled in the art, as taught by Greene et al. Protective Groups in Organic Synthesis, John Wiley and Sons, Second Edition, 1991, and then the 2'-OH can be reduced with a suitable reducing agent. Optionally, the 2'-hydroxyl can be activated to facilitate reduction; i. e. via the Barton reduction.
In another embodiment of the invention, the L-enantiomers are desired. Therefore, the L-enantiomers can be corresponding to the compounds of the invention can be prepared following the same foregoing general methods, beginning with the corresponding L- pentodialdo-furanose as starting material.
E. General Synthesis of 2'and/or 3S-Prodrugs The key starting material for this process is an appropriately substituted 1', 2', 3'or 4'-branched P-D or P-L nucleosides. The branched nucleoside can be purchased or can be prepared by any known means including the techniques disclosed herein. The branched nucleoside can be optionally protected with a suitable protecting group, preferably with a silyl group, by methods well known to those skilled in the art, as taught by Greene et al.
Protective Groups in Organic Synthesis, John Wiley and Sons, Second Edition, 1991. The optionally protected branched nucleoside can then be coupled with a suitable acyl doner, such as an acyl chloride and/or an acyl anhydride with the appropriate protic or aprotic solvent at a
suitable temperature, to give the 2'and/or 3'prodrug of 1', 2', 3'or 4'-branched ß-D or ß-L nucleoside. (Synthetic Communications, 1978, 8 (5), 327-333; J. Am. Chem. Soc., 1999, 121 (24), 5661-5664. ) Alternatively, the optionally protected branched nucleoside can then be coupled with a suitable acyl, such as a carboxylic acid, such as alkanoic acid and/or amino acid residue, optionally with a suitable coupling agent, with the appropriate aprotic solvent at a suitable temperature, to give the 2'and/or 3'prodrug of 1', 2', 3'or 4'-branched P-D or ß-L nucleoside. Possible coupling reagents are any reagents that promote coupling, including but are not limiting to, Mitsunobu reagents (e. g. diisopropyl azodicarboxylate and diethyl azodicarboxylate) with triphenylphosphine or various carbodiimides. In one embodiment, for a 3'-prodrug of a 2'-branched nucleoside, the nucleoside is preferably not protected and is directly coupled to an alkanoic acid or amino acid residue with an appropriate coupling reagient, such as a carbodiimide.
For example, simple amino-alcohols can be esterified using acid chlorides in refluxing acetonitrile-benzene mixture (See Scheme 9 below: Synthetic Communications, 1978, 8 (5), 327-333; hereby incorporated by reference). Alternatively, esterification can be achieved using an anhydride, as described in J. Am. Chem. Soc., 1999, 121 (24), 5661-5664, which is hereby incorportated by reference. See Figures 2,3 and 4.
Scheme 9 NEZ. CI 1-il-N NH2. HCI t'I', 'N N 0 L-valinoyl chloride HO N 0- O O OH AcN/toluene/reflux OH OH HCI. NH, The present invention is described by way of illustration, in the following examples.
It will be understood by one of ordinary skill in the art that these examples are in no way limiting and that variations of detail can be made without departing from the spirit and scope of the present invention.
EXAMPLE 1 : PREPARATION OF 1'-C-METHYLRIBOADENINE VIA 6-AMINO-9- (1-DEOXY- (3- D-PSICOFURANOSYL) PURINE Melting points were determined on a Mel-temp II apparatus and are uncorrected.
NMR spectra were recorded on a Bruker 400 AMX spectrometer at 400 MHz for'H NMR and 100 MHz for 13C NMR with TMS as internal standard. Chemical shifts (6) are reported in parts per million (ppm), and signals are reported as s (singlet), d (doublet), t (triplet), q (quartet), m (multiplet), or bs (broad singlet). IR spectra were measured on a Nicolet 51 ou FT-IR spectrometer. Mass spectra were recorded on a Micromass Autospec high-resolution mass spectrometer. TLC were performed on Uniplates (silica gel) purchased from Analtech Co. Column chromatography was performed using either silica gel-60 (220-440 mesh) for flash chromatography or silica gel G (TLC grade, > 440 mesh) for vacuum flash column chromatography. UV spectra were obtained on a Beckman DU 650 spectrophotometer.
Elemental analysis was performed by Atlantic Microlab, Inc. , Norcross, GA, or Galbraith Laboratories, Inc. , Knoxville, TN. HPLC was performed with a Waters HPLC system (Millipore Corporation, Milord, MA) equipped with a Model 600 controller, a Model 996 photodiode array detector and a Model 717 plus autosampler. Millennium 2010 software was used for system control, data acquisition and processing. A chiralyser polarimetric detector, Perkin-Elmer Model 241MC polarimeter (Wilton, CT), was used for the determination of optical rotations.
The title compound can be prepared according to a published procedure (J. Farkas, and F. Sorm, "Nucleic acid components and their analogues. XCIV. Synthesis of 6-amino-9- (l-deoxy-ß-D-psicofuranosyl) purine", Collect. Czech. Chem. Commun. 1967,32, 2663-2667.
J. Farkas", Collect. Czech. Chem. Commun. 1966,31, 1535) (Scheme 10).
Scheme 10 0 11 /N N 6-Benzamidopurine NH Ct p-TolO O Br chloromercuri salt p-TOIO N'O - l Br Br p-TolO Op-Tol p-TolO Op-Tol 1) Bu3SnH, AIBN NH2/2) (MeO) 2Ba/MeOH N N Ho HO O wCH3 OH OH In a similar manner, but using the appropriate sugar and pyrimidine or purine bases, the following nucleosides of Formula I are prepared.
wherein R', R2, R3, Xi, X2, and Y are defined in Table 1.
Alternatively, the following nucleosides of Formula IV are prepared, using the appropriate sugar and pyrimidine or purine bases.
wherein R', R2, R3, X1, Y are defined in Table 2.
Alternatively, the following nucleosides of Formula VII are prepared, using the appropriate sugar and pyrimidine or purine bases.
wherein Rl, R2, R3, R6, X, and Base are defined in Table 3.
Alternatively, the following nucleosides of Formula VIII are prepared, using the appropriate sugar and pyrimidine or purine bases.
wherein R1, R2, R6, X, and Base are defined in Table 4. Alternatively, the following nucleosides of Formula XXI are prepared, using the appropriate sugar and pyrimidine or purine bases.
wherein Rl, R2, R6, X and Base are defined in Table 5.
Alternatively, the following nucleosides of Formula XIII are prepared, using the appropriate sugar and pyrimidine or purine bases.
wherein R1, R6, R, R, X, Base, Rl° and R9 are defined in Table 6.
EXAMPLE 2 : PREPARATION OF 2'-C-METHYLRIBOADENINE The title compound was prepared according to a published procedure (R. E. Harry- O'kuru, J. M. Smith, and M. S. Wolfe,"A short, flexible route toward 2'-C-branched ribonucleosides", J. Org. Chem. 1997,62, 1754-1759) (Scheme 11).
Scheme lla
(a) Dess-Martin periodinane; (b) MeMgBr/TiCl4 ; (c) BzCI, DMAP, Et3N; (d) bis (trimethylsilyl) acetamide, Benzoyl adenine, TMSOTf ; (e) NH3/MeOH The 3'-prodrug of the 2'-branched nucleoside was prepared according to published procedure (Synthetic Communications, 1978, 8 (5), 327-333; J. Am. Chem. Soc., 1999, 121 (24), 5661-5664). Alternatively, the 2'-branched nucleoside can be esterified without protection (Scheme llb). Carbonyldiimidazole (377 mg, 2.33 mmol) was added to a solution of N- (tert-butoxycarbonyl)-L-valine (507 mg, 2.33 mmol) in 15 mL of anhydrous tetrahydrofuran. The mixture was stirred at 20 °C for one hour and at 50 °C for 10 minutes and then added to a solution of 4-Amino-1- (3, 4-dihydroxy-5-hydroxymethyl-3-methyl- tetrahydro-furan-2-yl)-IH-pyrimidine-2-one (500 mg, 1.95 mmol), 4- (dimethylamino) pyridine (25 mg, 0.195 mmol), triethylamine (5 mL) in anhydrous N, N- dimethylformamide (10 mL), which is also stirring at 50 °C. The reaction mixture was stirred at 50 °C for one hour and then examined by HPLC*. HPLC analysis indicated the formation of 52% of the desired ester, 17% of starting material in addition to undesired by-products.
The 3'-OH of 4-amino-l- (3, 4-dihydroxy-5-hydroxymethyl-3-methyl-tetrahydro-furan-2-yl)- IH-pyrimidine-2-one tends to react selectively when coupled with BOC-Val.
Scheme lib
The product was analyzed by HPLC using a reverse phase column : Waters part # WAT086344; Nova-Pak C18, 60A pore size, 4pm particle size, 3.9 x 150 mm.
Chromatograms were generated using a Waters 2695 HPLC and 996 PDA detector. Mobile Phase: HPLC grade acetonitrile and water were bought from JT Baker and 1M solution of triethylammonium acetate from Fluka.
Flow rate: 1. 00 mL/min. of an acetonitrile/20mM aqueous triethylammonium acetate buffer gradient as described below.
System is equilibrated for five minutes between runs.
Wave length : 272 nm.
Table D: Column Specifications Time % Acetonitrile % Buffer 0. 00 0. 00 100. 0 15. 00 80. 0 20. 0 30. 00 80. 0 20. 0 Table E: Description of compounds vs. retention times: Compound RETENTION TIME (IN MINUTES) Desired ester 8.3 DMAP 3. 7 (Broad Peak) Starting material 2.7
In a similar manner, but using the appropriate sugar and pyrimidine or purine bases, the following nucleosides of Formula II are prepared.
wherein R2, R3, XI, X2, and Y are defined in Table 7.
Alternatively, the following nucleosides of Formula V are prepared, using the appropriate sugar and pyrimidine or purine bases.
wherein R', R2, R3, Xl and Y are defined in Table 8.
Alternatively, the following nucleosides of Formula IX are prepared, using the appropriate sugar and pyrimidine or purine bases.
(IX) wherein Rl, R2, R3, R6, X, and Base are defined in Table 9.
Alternatively, the following nucleosides of Formula X are prepared, using the appropriate sugar and pyrimidine or purine bases.
wherein Rl, R2, R7, R6, X, and Base are defined in Table 10.
Alternatively, the following nucleosides of Formula XXII are prepared, using the appropriate sugar and pyrimidine or purine bases.
wherein Rl, R2, R6, X, and Base are defined in Table 11.
Alternatively, the following nucleosides of Formula XIII are prepared, using the appropriate sugar and pyrimidine or purine bases.
(XIII) wherein Rl, R6, R7, X, Base, R9 and Rl° are defined in Table 12.
EXAMPLE 3 : PREPARATION OF 3'-C-METHYLRIBOADENINE The title compound can be prepared according to a published procedure (R. F. Nutt, M. J. Dickinson, F. W. Holly, and E. Walton,"Branched-chain sugar nucleosides. III. 3'-C- methyladenine", J. Org. Chem. 1968, 33, 1789-1795) (Scheme 12).
Scheme 12
(a) Ru02/NaI04 ; (b) MeMgI/TiCl4 ; (c) HCI/MeOH/H20 ; (d) BzCl/pyridine ; (e) AcBr, HBr/AcOH ; (f) chloromercuri-6-benzamidopurine ; (g) NH3/MeOH.
In a similar manner, but using the appropriate sugar and pyrimidine or purine bases, the following nucleosides of Formula III are prepared.
(Ill) wherein Rl, R2, R3, Xl, X2, and Y are defined in Table 13.
Alternatively, the following nucleosides of Formula VI are prepared, using the appropriate sugar and pyrimidine or purine bases.
wherein R', R2, R3, Xl, and Y are defined in Table 14.
Alternatively, the following nucleosides of Formula XI are prepared, using the appropriate sugar and pyrimidine or purine bases.
wherein R1, R2, R3, R6, X, and Base are defined in Table 15.
Alternatively, the following nucleosides of Formula XII are prepared, using the appropriate sugar and pyrimidine or purine bases.
wherein Rl, R2, R6, X and Base are defined in Table 16.
Alternatively, the following nucleosides of Formula XXIII are prepared, using the appropriate sugar and pyrimidine or purine bases.
wherein Rl, R2, R6, X and Base are defined in Table 17.
Alternatively, the following nucleosides of Formula XV are prepared, using the appropriate sugar and pyrimidine or purine bases.
wherein Rl, R6, R7, X, Base, R 8 and R9 are defined in Table 18.
EXAMPLE 4: PREPARATION OF 1-0-METHYL-2, 3-O-ISOPROPYLIDENE-ß-D- RIBOFURANOSE (AA) The title compound can be prepared according to a published procedure (Leonard, N.
J.; Carraway, K. L. "5-Amino-5-deoxyribose derivatives. Synthesis and use in the preparation of"reversed"nucleosides"J. Heterocycl. Chem. 1966,3, 485-489).
A solution of 50.0 g (0.34 mole) of dry D-ribose in 1.0 L of acetone, 100 mL of 2,2- dimethoxypropane, 200 mL of methanol containing 20 mL of methanol saturated with hydrogen chloride at 0°C was stirred overnight at room temperature. The resulting solution was neutralized with pyridine and evaporated under reduced pressure. The resulting oil was partitioned between 400 mL of water and 400 mL of methylene chloride. The water layer was extracted twice with methylene chloride (400 mL). The combined organic extracts were dried over sodium sulfate and evaporated under reduced pressure. The residue was purified by silica gel column chromatography [eluent: stepwise gradient of methanol (1-2%) in methylene chloride] to give pure AA (52.1 g, 75%) as a yellow syrup.'H-NMR (CDC13) : 8 5.00 (s, 1 H, H-1), 4.86 (d, I H, H-2, J2-3 = 5.9 Hz), 4.61 (d, 1H, H-3, J3-2 = 5.9 Hz), 4.46 (t, 1H, H-4, J45 = 2.7 Hz), 3.77-3. 61 (m, 2H, H-5 and H-5'), 3.46 (s, 1H, OCH3), 3.0-2. 4 (br s, 1H, OH-5), 1.51 (s, 3H CH3), 1.34 (s, 3H CH3) ; MS (matrix GT): FAB>0 m/z 173 (M- OCH3) +.
EXAMPLE 5 : PREPARATION OF 1-O-METHYL-2, 3-O-ISOPROPYLIDENE- (3-D- PENTODIALDO-RIBOFURANOSE (BB) The title compound can be prepared according to a published procedure (Jones, G. H.; Moffatt, J. G. Oxidation of carbohydrates by the sulfoxide-carbodiimide and related methods.
Oxidation with dicyclohexylcarbodiimide-DMSO, diisopropylcarbodiimide-DMSO, acetic anhydride-DMSO, and phosphorus pentoxide-DMSO: in Methods in Carbohydrate Chemistry ; Whisler, R. L. and Moffatt, J. L. Eds; Academic Press: New York, 1972; 315- 322).
Compound AA was co-evaporated twice with anhydrous pyridine.
Dicyclohexylcarbodi-imide (DCC, 137.8 g, 0.67 mol) was added to a solution of AA (68.2 g, 0.33 mole) in anhydrous benzene (670 mL), DMSO (500 mL) and pyridine (13.4 mL). To the resulting solution, cooled to 0°C, was added a solution of anhydrous crystalline orthophosphoric acid (16.4 g, 0.167 mmol) in anhydrous DMSO (30 mL). The mixture was
stirred for 1.5 hours at 0°C and 18 hours at room temperature under argon atmosphere, diluted with ethyl acetate (1000 mL). A solution of oxalic acid dihydrate (63.1 g, 038 mol) in DMSO (30 mL) was added and the reaction mixture was stirred at room temperature during 1 hour and then filtered to eliminate precipitated dicyclohexylurea (DCU). The filtrate was concentrated to a volume of about 600 mL under reduced pressure and neutralized with a saturated aqueous sodium hydrogen carbonate solution (400 mL). Brine (200 mL) was added and the organic layer was extracted with ethyl acetate (4x 1000 mL). The combined organic layers were concentrated to a volume of about 2000 mL, washed with a saturated aqueous sodium hydrogen carbonate solution (2x 700 mL), and with brine (2x 700 mL) before being dried over sodium sulfate and evaporated under reduced pressure. A small fraction of the crude residue was purified on silica gel chromatography [eluent : chloroform/ethyl ether, 8: 2] in order to confirm the structure of BB which was obtained as a pale yellow solid.'H-NMR (CDC13) : 5 9.61 (s, 1H, H-5), 5.12 (s, 1H, H-1), 5.08 (d, 1H, H-2, J2-3 = 5.9 Hz), 4.53 (d, 1H, H-3, J3-2 = 6.0 Hz), 4.51 (s, 1H, H-4), 3.48 (s, 1H, OCH3), 1.56 (s, 3H CH3), 1.36 (s, 3H CH3); MS (matrix GT): FAB>0 m/z 203 (M+H) +, 171 (M-OCH3) +.
EXAMPLE 6 : PREPARATION OF 4-C-HYDROXYMETHYL-1-0-METHYL-2, 3-0- ISOPROPYLIDENE-P-D-RIBOFURANOSE (CC) The title compound can be prepared according to a published procedure (Leland, D.
L.; Kotick, M. P. Carbohydr. Res. 1974, 38, C9-C11 ; Jones, G. H.; Taniguchi, M. , et al. J.
Org. Chem 1979, 44, 1309-1317 ; Gunic, E.; Girardet, J. -L. ; et al. Bioorg Med. Chem 2001, 9,163-170).
To a solution of the crude material (BB) obtained above and 37% aqueous formaldehyde (167 mL) in dioxane (830 mL) was added aqueous sodium hydroxyde (2N, 300 mL). The mixture was stirred at room temperature for 4 hours and neutralized by addition of Dowex 50 W X 2 (H+ form). The resin was filtered, washed with methanol, and the combined filtrates were concentrated to dryness and coevaporated several times with absolute ethanol. Sodium formate which was precipitated from absolute ethanol was removed by filtration, the filtrate was concentrated to dryness and the residue was purified by silica gel column chromatography [eluent : stepwise gradient of methanol (0-4%) in chloroform] to give pure CC (42.2 g, 54% from AA), which was recrystallized from cyclohexane. Mp = 94-95 (dec. ) (lit. 94-96.5 ; 97-98: Refs: 3, 4),'H-NMR (DMSO-d6): 8 4.65 (s, 1H, H-1), 4.44-4. 37 (m, 3H, H-2, H-3 and OH-6), 4.27 (t, IH, OH-5, J = 5.6 Hz, J = 6.0 Hz), 3.42-3. 34 (m, 2H,
H-5 and H-6) 3.29 (dd, 1H, H-5', J5'-OH = 5.4 Hz, J5-5'= 11.4 Hz), 3.11 (dd, 1H, H-6', J6'-OH = 5.7 Hz, J6-6'= 10.9 Hz), 3.03 (s, 3H, OCH3), 1.48 (s, 3H CH3), 1.05 (s, 3H CH3) ; MS (matrix GT): FAB>0 mlz 469 (2M+H) +, 235 (M+H) +, 203 (M-OCH3) + FAB<0 mlz 233 (M-H)-.
EXAMPLE 7: PREPARATION OF 6-O-MONOMETHOXYTRITYL-4-C-HYDROXYMETHYL-1- 0-METHYL-2, 3-O-ISOPROPYLIDENE--D-RIBOFURANOSE (DD) The title compound can be prepared according to a published procedure (Gunic, E.; Girardet, J. -L. ; et al. Bioorg. Med. Chem 2001, 9, 163-170).
To a solution of CC (41.0 g, 175 mmol) in pyridine (700 ml) was added by portions dimethoxytrityl chloride (60.5 g, 178 mmol) at 4°C. The reaction mixture was stirred for 3 hours at room temperature. After addition of methanol, the reaction mixture was concentrated (200 ml) and then dissolved with ethyl acetate (2 L). The organic layer was washed with a 5% aqueous sodium hydrogen carbonate solution, with water and dried over sodium sulfate and then evaporated to dryness. Purification by silica gel column chromatography [eluent: ethyl acetate/hexane 15/85] afforded pure DD (63.0 g, 68%) as a syrup.'H-NMR (CDC13) : S 7.5-6. 9 (m, 13H, MMTr), 4.89 (s, 1H, H-l), 4.72-4. 62 (m, 3H, H-2, H-3 and OH-5), 3.82 (dd, 1H, H-5, J5-OH = 5.5 Hz, J5-5'= 10.5 Hz), 3.79 (s, 6H, OCH3), 3.54 (dd, 1H, H-5', J56-OH = 4.9 Hz, J5,-5 = 10.5 Hz), 3.31 (s, 3H, OCH3), 3. 24 (d, 1H, H-6, J6-6, = 9.2 Hz), 3.13 (d, IH, H-6', J6 = 9.2 Hz), 1.24 (s, 3H CH3), 1.15 (s, 3H CH3); MS (matrix GT): FAB>0 m/z 303 (DMTr) +.
EXAMPLE 8: PREPARATION OF5-0-BENZOYL-4-C-HYDROXYMETHYL-1-0-METHYL-2, 3- O-ISOPROPYLIDENE- (3-D-RIBO-FURANOSE (EE) The title compound can be prepared according to a published procedure (Gunic, E.; Girardet, J. -L. ; Pietrzkowski, Z.; Esler, C.; Wang, G. "Synthesis and cytotoxicity of 4'-C-and 5'-C-substituted Toyocamycins"Bioorg. Med. Chem. 2001,9, 163-170).
To a solution of DD (2.51 g, 4.68 mmol) in anhydrous pyridine (37 mL) was added under argon benzoyl chloride (1.09 mL, 9.36 mmol) and the reaction mixture was stirred for 13 hours at to room temperature. Then the reaction was cooled to 0°C and stopped with ice- cold water (100 mL). The water layer was extracted with methylene chloride (301 200 mL).
The combined organic layers were washed with a saturated aqueous sodium hydrogen carbonate solution (2x 150 mL), with water (lx 150 mL) and then dried over sodium sulfate
and evaporated under reduced pressure. The residue was dissolved in 80% acetic acid (70.2 mL) and the mixture was stirred at room temperature for 3hr and concentrated to dryness.
Purification by silica gel column chromatography [eluent: chloroform] afforded pure EE (1.40 g, 88%) as a syrup.'H-NMR (CDC13) : 8 8.1-7. 4 (m, 5H, C6HsCO), 5.08 (s, 1H, H-1), 4.77 (dd, 2H, H-2 and H-3, J = 6. 1 Hz, J = 8.2 Hz), 4.51 (q, 2H, H-5 and H-5', J = 11.5 Hz, J5-s'= 23.8 Hz), 3.91 (t, 2H, H-6 and H-6', J = 12.3 Hz), 4.38 (s, 1H, OCH3), 2.2-1. 8 (brs, 1H, OH-6), 1.57 (s, 3H CH3), 1.38 (s, 3H CH3); MS (matrix GT): FAB>0 m/z 677 (2M+H) +, 339 (M+H) +, 307 (M-OCH3) +, 105 (C6H5CO) FAB<0 m/z 121 (C6H5C02).
EXAMPLE 9: PREPARATION OF 5-0-BENZOYL-4-C-METHYL-1-0-METHYL-2, 3-0- lSOPROPYLIDENE-ß-D-RIBOFURANOSE (FF) The title compound can be prepared according to a published procedure (Gunic, E.; Girardet, J. -L. ; etal. Bioorg. Med. Chem. 2001,9, 163-170).
A solution of EE (37.6 g, 0.111 mol), 4-dimethylaminopyridine (DMAP, 40.7 g, 0.333 mol) and phenoxythiocarbonyle chloride in anhydrous acetonitrile (1000 mL) was stirred at room temperature for 1 hour and concentrated to dryness. The residue was dissolved in methylene chloride (500 mL) and successively washed with 0.2 M hydrochloric acid (2x 500 mL) and water (500 mL) before being dried over sodium sulfate, evaporated under reduced pressure and coevaporated several times with anhydrous toluene. The crude material was dissolved in anhydrous toluene (880 mL) and tris (trimethylsilyl) silane (TMSS, 42.9 mL, 0.139 mol), and 1, 1'-azobis (cyclohexanecarbonitrile) (ACCN, 6.8 g, 27.8 mmol) were added. The reaction mixture was stirred under reflux for 45 minutes, cooled to room temperature and concentrated under reduced pressure. The resulting residue was purified by silica gel column chromatography [eluent : stepwise gradient of diethyl ether (5-20%) in petroleum ether] to give pure FF (26.4 g, 74%) as a pale yellow syrup.'H-NMR (DMSO- d6) : 8 8.0-7. 5 (m, 5H, C6H5CO), 4.85 (s, IH, H-l), 4.63 (dd, 2H, H-2 and H-3, J = 6.1 Hz, J = 11.6 Hz), 4.24 (d, 1H, H-5, Js. 5- = 11.1 Hz), 4.10 (d, 1H, H-5', J5 5 = 11.1 Hz), 3.17 (s, 1H, OCH3), 1.38 (s, 3H CH3), 1.30 (s, 3H CH3), 1.25 (s, 3H CH3); MS (matrix GT): FAB>0 m/z 291 (M-OCH3) +, 105 (C6HsCO) FAB<0 m/z 121 (C6H5C02)-
EXAMPLE 10: PREPARATION OF 5-O-BENZOYL-4-C-METHYL-1, 2, 3-O-ACETYL-a, (3-D- RIBOFURANOSE (GG) Compound FF (22.5 g, 70 mmol) was suspended in a 80% aqueous acetic acid solution (250 mL). The solution was heated at 100°C for 3 hours. The volume was then reduced by half and coevaporated with absolute ethanol and pyridine. The oily residue was dissolved in pyridine (280 mL) and then cooled at 0°C. Acetic anhydride (80 mL) and 4- dimethylamino-pyridine (500 mg) were added. The reaction mixture was stirred at room temperature for 3 hours and then concentrated under reduced pressure. The residue was dissolved with ethyl acetate (1 L) and successively washed with a saturated aqueous sodium hydrogen carbonate solution, a 1 M hydrochloric acid and water. The organic layer was dried over sodium sulfate and evaporated under reduced pressure. The resulting residue was purified by silica gel column chromatography [eluent: stepwise gradient of diethyl ether (30- 40%) in petroleum ether] to give pure GG (16.2 g, 60%) as a pale yellow syrup. A small fraction of the material was re-purified on silica gel chromatography [same eluent: system] in order separate the a and the P anomers. a anomer :'H-NMR (DMSO-d6): # 8.1-7. 5 (m, 5H, C6H5CO), 6.34 (pt, 1H, H-1, J = 2. 4 Hz, J = 2,1 Hz), 5.49 (m, 2H, H-2 and H-3), 4.33 (q, 2H, H-5 and H-5', J = 11.6 Hz, J = 18. 7 Hz), 2.15 (s, 3H, CH3CO2), 2.11 (s, 3H, CH3CO2), 2.07 (s, 3H, CH3CO2), 1.37 (s, 3H, CH3) ; MS (matrix GT): FAB>0 m/z 335 (M-CH3CO2-) +, 275 (M-CH3CO2-+H)+, 105 (C6H5CO) +, 43 (CH3CO) + FAB<0 m/z 121 (C6H5C02), 59 (CH3C02)-.
(3 anomer :'H-NMR (DMSO-d6) : 8 8.1-7. 5 (m, 5H, C6H5CO), 5.99 (s, 1H, H-1), 5.46 (d, 1H, H-2, J2-3 = 5.3 HZ), 5.30 (d, 1H, H-2, J2-3 = 5.3 Hz), 4.39 (d, 1H, H-5, -5-= 11.7 Hz), 4.19 (d, 1H, H-5', J5'-S = 11.7 Hz), 2.10 (s, 3H, CH3C02), 2.06 (s, 3H, CH3CO2), 2.02 (s, 3H, CH3C02), 1.30 (s, 3H, CH3); MS (matrix GT): FAB>0 m/z 335 (M-CH3CO2-) +, 275 (M- CH3CO2-+H)+, 105 (C6H5CO), 43 (CH3CO) + FAB<O mlz 121 (C6H5CO2)-, 59 (CH3C02)-.
EXAMPLE 11 : PREPARATION OF 1-(5-O-BENZOYL-4-C-METHYL-2s3-O-ACETYL-p-D RIBOFURANOSYL) URACIL (HH) A suspension of uracil (422 mg, 3.76 mmol) was treated with hexamethyldisilazane (HMDS, 21 mL) and a catalytic amount of ammonium sulfate during 17 hours under reflux.
After cooling to room temperature, the mixture was evaporated under reduced pressure, and the residue, obtained as a colorless oil, was diluted with anhydrous 1, 2-dichloroethane (7.5
mL). To the resulting solution was added GG (0.99 g, 2.51 mmol) in anhydrous 1,2- dichloroethane (14 mL), followed by addition of trimethylsilyl trifluoromethanesulfonate (TMSTf, 0.97 mL, 5.02 mmol). The solution was stirred for 2.5 hours at room temperature under argon atmosphere, then diluted with chloroform (150 mL), washed with the same volume of a saturated aqueous sodium hydrogen carbonate solution and finally with water (2x 100 mL). The organic phase was dried over sodium sulfate, then evaporated under reduced pressure. The resulting crude material was purified by silica gel column chromatography [eluent: stepwise gradient of methanol (0-2%) in chloroform] to afford pure HH (1.07 g, 95%) as a foam.'H-NMR (DMSO-d6): 8 11.48 (s, 1H, NH), 8.1-7. 5 (m, 6H, C6H5CO and H-6), 5.94 (d, 1H, H-1', J1'-2'= 3.3 Hz), 5.61 (m, 3H, H-5, H-2'and H-3'), 4.47 (d, 1H, H-5', J5'-5'' = 11.7 Hz), 4.35 (d, 1H, H-5", Js 5 = 11.7 Hz), 2.12 (s, 3H, CH3CO2), 2.09 (s, 3H, CH3CO2), 1.38 (s, 3H, CH3); MS (matrix GT): FAB>0 m/z 893 (2M+H) +, 447 (M+H) +, 335 (S) +, 113 (BH2) +, 105 (C6H5CO) +, 43 (CH3CO) + FAB<0 m/z 891 (2M-H)-, 445 (M-H)-, 121 (C6H5CO2)-, 111 (B)-, 59 (CH3CO2)-.
EXAMPLE 12 : PREPARATION OF 1- (4-C-METHYL- (-D-RIBOFURANOSYL) URACIL (II) The title compound can be prepared according to a published procedure from HH (Waga, T.; Nishizaki, T.; et al. Biosci. Biotechnol. Biochem. 1993, 57, 1433-1438).
A solution of HH (610 mg, 1.37 mmol) in methanolic ammonia (previously saturated at-10°C) (27 mL) was stirred at room temperature overnight. The solvent was evaporated under reduced pressure and the residue was partitioned between methylene chloride (40 mL) and water (40 mL). The aqueous layer was washed with methylene chloride (2x 40 mL), concentrated under reduced pressure and coevaporated several times with absolute ethanol.
Recrystallization from a mixture absolute ethanol/methanol gave II (215 mg, 61%) as a colorless and crystalline solid. Mp: 226-227 (dec. ) (lit. 227: Ref. 6); UV (H20) : may = 259 nm (# = 101000), #min = 228 nm (# = 2200); HPLC 99. 56%,'H-NMR (DMSO-d6) : 8 11.28 (s, 1H, NH), 7.89 (d, 1H, H-6, J6-s = 8.1 Hz), 5.80 (d, 1H, H-l', Jl'-2'= 7.1 Hz), 5.64 (d, 1H, H-5, J5 = 8.1 Hz), 5.24 (d, 1H, OH-2', JOH-2'= 6.5 Hz), 5.18 (t, 1H, OH-5' JOH-5' =JOH-5" = 5.2 Hz), 5.01 (d, 1H, OH-3', JOH-3'= 5.0 Hz), 4.28 (dd, 1H, H-2', J = 6.5 Hz, J = 12.2 Hz), 3.90 (t, 1H, H-3', J3-2 = J3'-OH = 5.1 Hz), 3.30 (m, 2H, H-5'and H-5"), 1.06 (s, 3H, CH3) ; MS (matrix GT): FAB>0 m/z 517 (2M+H) +, 259 (M+H) +, 147 (S) + FAB<0 m/z 515 (2M-H)-, 257 (M-H)-.
EXAMPLE 13: PREPARATION OF 1-(5-O-BENZOYL-4-C-METHYL-2,3-O-ACETYL-ß-D- RIBOFURANOSYL) 4-THIO-URACIL (JJ) Lawesson's reagent (926 mg, 2.29 mmol) was added under argon to a solution of HH (1.46 g, 3.27 mmol) in anhydrous 1,2-dichloroethane (65 mL) and the reaction mixture was stirred overnight under reflux. The solvent was evaporated under reduced pressure and the residue was purified by silica gel column chromatography [eluent: stepwise gradient of methanol (1-2%) in chloroform] to give pure JJ (1.43 g, 95%) as a yellow foam.'H-NMR (DMSO-d6): # 12.88 (s, 1H, NH), 8.1-7. 5 (m, 6H, C6H5CO and H-6), 6.27 (d, 1H, H-l', Ji.. 2- = 7.51 Hz), 5.91 (br s, 1H, H-5) 5.64 (m, 2H, H-2'and H-3'), 4.47 (d, 1H, H-5', J5'-5" = 11.7 Hz), 4.36 (d, 1H, H-5', J5'-5'' =11. 7 Hz), 2.11 (s, 3H, CH3CO2), 2.09 (s, 3H, CH3C02), 1.39 (s, 3H, CH3); MS (matrix GT): FAB>0 m/z 925 (2M+H) +, 463 (M+H) +, 335 (S) +, 129 (BH2) +, 105 (C6H5CO) +, 43 (CH3CO) + FAB<0 m/z 461 (M-H)-, 127 (B)-, 121 (C6H5CO2)-, 59 (CH3CO2)-.
EXAMPLE 14: PREPARATION OF 1-(4-C-METHYL-ß-D-RIBOFURANOSYL)4-THIO-URACIL (KK) KK) A solution of JJ (500 mg, 1.08 mmol) in methanolic ammonia (previously saturated at-10°C) (27 mL) was stirred at room temperature overnight. The solvent was evaporated under reduced pressure and the residue was partitioned between methylene chloride (40 ml) and water (40 mL). The aqueous layer was washed with methylene chloride (2x 40 mL), concentrated under reduced pressure. The crude material was purified by silica gel column chromatography [eluent: stepwise gradient of methanol (5-7%) in methylene chloride] to give pure KK (188 mg, 63%), which was lyophilized. Mp: 65-70 (dec. ) ; UV (methanol): knaw = 330 nm (£ = 20000) 246 nm (£ = 4200), #min = 275 nm (e = 1500) ;'H-NMR (DMSO-d6) : # 12.51 (brs, 1H, NH), 7.81 (d, 1H, H-6, J6-5 = 7.6 Hz), 6.30 (d, 1H, H-5, J5-6 = 7.5 Hz), 5.77, (d, 1H, H-1', Jl-2 = 6.7 Hz), 5.32 (d, 1H, OH-2', JOH-2' = 6.1 Hz), 5.20 (t, 1H, OH-5'Jon-5 = JOH-5"= 5.2 Hz), 5.03 (d, 1H, OH-3', JOH-3' = 5.2 Hz), 4.17 (dd, 1H, H-2', J = 6.2 Hz, J = 12,0 Hz), 3.89 (t, 1H, H-3', J3'-2' = J3'-OH' = 5.1 Hz), 3.35 (m, 2H, H-5'and H-5"), 1.02 (s, 3H, CH3); MS (matrix GT): FAB>0 mlz 275 (M+H) +, 147 (S) +, 129 (BH2) + FAB<0 mlz 547 (2M-H)-, 273 (M-H) 127 (B)-.
EXAMPLE 15: PREPARATION OF 1- CYTOSINES HYDROCHLORIC FORM (LL) Compound KK (890 mg, 1.93 mmol) was treated with methanolic ammonia (previously saturated at-10°C), (12 mL) at 100°C in a stainless-steel bomb for 3 hours, then cooled to room temperature. The solvent was evaporated under reduced pressure and the residue was partitioned between methylene chloride (40 mL) and water (40 mL). The aqueous layer was washed with methylene chloride (2x 40 mL), concentrated under reduced pressure. The crude material was purified by silica gel column chromatography [eluent : methylene chloride/methanol/ammonium hydroxide 65: 30: 5]. The collected fractions were evaporated under reduced pressure and in absolute ethanol (6.3 mL). To the solution was added a 2N hydrochloric acid solution (1.5 mL) and the mixture was stirred before being concentrated under reduced pressure. The procedure was repeated twice and LL was precipitated from absolute ethanol. Mp: 213-214 (dec. ) ; UV (methanol): , a,, = 280 nm (s = 9800), knin = 245 nm (E = 3600) ;'H-NMR (DMSO-d6): 8 9.82 (s, 1H, NH2), 8.72 (s, 1H, NH2), 8.34 (d, 1H, H-6, J6-5 = 7.8 Hz), 6.21 (d, 1H, H-5, J5-6 = 7.8 Hz), 5.83 (d, 1H, H-l', Je'-2' = 5.8 Hz), 4.22 (d, 1H, OH-2', JoH-2'= 6.5 Hz), 5.6-4. 7 (m, 3H, OH-2', OH-3'and OH-5'), 4.28 (t, 1H, H-2', J = 5.6 Hz), 3.99 (d, 1H, H-3', J = 5.3 Hz), 3.43 (m, 2H, H-5'and H-5"), 1.14 (s, 3H, CH3) ; MS (matrix GT): FAB>0 m/z 515 (2M+H) +, 258 (M+H) +, 147 (S) +, 112 (BH2) + FAB<0 m/z 256 (M-H)-.
EXAMPLE 16: PREPARATION OF 1- (5-0-BENZOYL-4-C-METHYL-2, 3-0-ACETYL-P-D- RIBOFURANOSYL) THYMINE (MM) A suspension of thymine (384 mg, 3.04 mmol) was treated with hexamethyldisilazane (HMDS, 17 mL) and a catalytic amount of ammonium sulfate overnight under reflux. After cooling to room temperature, the mixture was evaporated under reduced pressure, and the residue, obtained as a colorless oil, was diluted with anhydrous 1,2-dichloroethane (6 mL).
To the resulting solution was added GG (1.0 g, 2.53 mmol) in anhydrous 1,2-dichloroethane (14 mL), followed by addition of trimethylsilyl trifluoromethanesulfonate (TMSTf, 0.98 mL, 5.06 mmol). The solution was stirred for 5 hours at room temperature under argon atmosphere, then diluted with chloroform (150 mL), washed with the same volume of a saturated aqueous sodium hydrogen carbonate solution and finally with water (2x 100 mL).
The organic phase was dried over sodium sulfate, then evaporated under reduced pressure.
The resulting crude material was purified by silica gel column chromatography [eluent: 2% of methanol in chloroform] to afford pure MM (1.09 g, 94%) as a foam. IH-NMR (DMSO- d6): # 11.47 (s, 1H, NH), 8.1-7. 4 (m, 6H, C6H5CO and H-6), 5.98 (d, 1H, H-1', J = 5.0 Hz), 5.5-5. 7 (m, 2H, H-2'and H-3'), 4.42 (dd, 2H, H-5'and H-5", J = 11.6 Hz, J = 31.6 Hz), 2.12 (s, 3H, CH3CO2), 2.09 (s, 3H, CH3CO2), 1.60 (s, 1H, CH3), 1.37 (s, 3H, CH3); MS (matrix GT): FAB>0 mlz 461 (M+H) +, 335 (S) +, 105 (C6H5CO) +, 43 (CH3CO) + FAB<0 m/z 459 (M- H)-, 125 (B)-, 121 (C6H5CO2)-, 59 (CH3CO2)-.
EXAMPLE 17: PREPARATION OF 1- (4-C-METHYL-P-D-RIBOFURANOSYL) THYMINE (NN) The title compound can be prepared according to a published procedure from MM (Waga, T.; Nishizaki, T.; et al. Biosci. Biotechnol. Biochem 1993, 57, 1433-1438).
A solution of MM (1.09 g, 2.37 mmol) in methanolic ammonia (previously saturated at-10°C) (60 mL) was stirred at room temperature overnight. The solvent was evaporated under reduced pressure and the residue was partitioned between methylene chloride (60 mL) and water (60 mL). The aqueous layer was washed with methylene chloride (2x 60 mL), concentrated under reduced pressure and coevaporated several times with absolute ethanol.
Recrystallization from methanol gave NN (450 mg, 70%) as a colorless and crystalline solid.
Mp: 258-260 (dec. ) (lit. 264: Ref. 6); UV (H20) : may = 264.4 nm (s = 8800), knin = 232.0 nm (e = 2200) ;'H-NMR (DMSO-d6) : 8 11.29 (s, IH, NH), 7.75 (s, 1H, H-6), 5.82 (d, 1H, H-1', J1'-2' = 7.2 Hz), 5.19 (m, 2H, OH-2', OH-5'), 5.02 (d, 1H, OH-3', JOH-3'= 5.0 Hz), 4.21 (dd, IH, H-2', J = 6.4 Hz, J = 12.3 Hz), 3.92 (t, 1H, H-3', J3'-2'=J3'OH'= 5.0 Hz), 3.30 (m, 2H, H-5'and H-5"), 1.78 (s, 3H, CH3), 1.09 (s, 3H, CH3); MS (matrix GT): FAB>0 m/z 545 (2M+H) +, 365 (M+G+H) +, 273 (M+H) +, 147 (S) +, 127 (B+2H) +, FAB<0 m/z 543 (2M-H)-, 271 (M-H)-, 125 (B)- ; [a] D20-32. 0 (c = 0.5 in H2O, litt. -26.4).
EXAMPLE 18 : PREPARATION OF 1-(592s3-TRI-O-ACETYL-4-C-METHYL-ß-D RIBOFURANOSYL) THYMINE (OO) A solution of NN (200 mg, 0.735 mmol) in anhydrous pyridine (7.4 ml) was treated with acetic anhydride (1.2 mL) and stirred at room temperature for 3 hours. The solvent was evaporated under reduced pressure, and the residue was purified by silica gel column chromatography [eluent : stepwise gradient of methanol (0-5%) in methylene chloride] to afford pure 00 (0.400 g, quantitative yield) as a foam.'H-NMR (DMSO-d6) : 5 11.45 (s, 1H,
NH), 7.56 (s, 1H, H-6), 5.90 (d, 1H, H-l', J1'-2' =4. 8 Hz), 5.5-5. 4 (m, 2H, H-2'and H-3'), 4.3- 4.0 (m, 2H, H-5'and H-5"), 2.1-2. 0 (m, 9H, 3 CH3CO2), 1.78 (s, 1H, CH3), 1.20 (s, 3H, CH3); MS (matrix GT): FAB>0 m/z 797 (2M+H) +, 399 (M+H) +, 339 (M-CH3CO2) +, 273 (S) +, 127 (BH2) +, 43 (CH3CO) + FAB<0 zn/z 795 (2M-H)-, 397 (M-H)-, 355 (M-CH3CO)-, 125 (B)-, 59 (CH3CO2)-.
EXAMPLE 19: PREPARATION OF 1-(5,2,3-TRI-O-ACETYL-4-C-METHYL-ß-D- RIBOFURANOSYL)-4-THIO-THYMINE (PP) Lawesson's reagent (119 mg, 0.29 mmol) was added under argon to a solution of 00 (0.167 g, 4.19 mmol) in anhydrous 1,2-dichloroethane (11 mL) and the reaction mixture was stirred overnight under reflux. The solvent was evaporated under reduced pressure and the residue was purified by silica gel column chromatography [eluent: stepwise gradient of methanol (1-2%) in chloroform] to give pure PP (0.165 g, 95%) as a yellow foam.'H-NMR (DMSO-d6) : 8 12.81 (s, 1H, NH), 7.64 (s, 1H, H-6), 5.84 (d, 1H, H-1', J1'-2 = 4.66 Hz), 5.5- 5.4 (m, 2H, H-2'and H-3'), 4.11 (dd, 2H, H-5'and H-5", J = 11.7 Hz, J = 31.3 Hz), 2.0-1. 8 (m, 12H, 3 CH3CO2 and CH3), 1.33 (s, 3H, CH3); MS (matrix GT): FAB>0 m/z 829 (2M+H) +, 415 (M+H) +, 273 (S) +, 143 (BH2) +, 43 (CH3CO) + FAB<0 m/z 827 (2M-H)-, 413 (M-H)-, 141 (B)-, 59 (CH3CO2)-.
In a similar manner, the following nucleosides of Formula XVII are prepared, using the appropriate sugar and pyrimidine bases. wherein RI, R2, R3, Xl and Y are defined in Table 19.
EXAMPLE 20: PREPARATION OF 1- (4-C-METHYL-P-D-RIBOFURANOSYL)-5-METHYL- CYTOSIN (QQ), HYDROCHLORIDE FORM Compound PP (0.160 g, 0.386 mmol) was treated with methanolic ammonia (previously saturated at-10°C), (10 mL) at 100°C in a stainless-steel bomb for 3 hours, then cooled to room temperature. The solvent was evaporated under reduced pressure and the residue was partitioned between methylene chloride (30 mL) and water (30 mL). The aqueous layer was washed with methylene chloride (2x 30 mL), concentrated under reduced pressure. The crude material was purified by silica gel column chromatography [eluent : 20% methanol in methylene chloride] to afford 1- (4-C-methyl-p-D-ribofuranosyl)-5-methyl- cytosine (60 mg, 57%). This compound was dissolved in EtOH 100 (1.5 mL), treated with a 2N hydrochloric acid solution (0.3 mL), and the mixture was stirred before being concentrated under reduced pressure. The procedure was repeated twice and QQ was precipitated from absolute ethanol. Mp: 194-200 (dec. ) ; UV (H20) : , na, = 275.6 nm (e = 7300), nin = 255 nm (E = 4700); HPLC 100%,'H-NMR (DMSO-d6): 8 9.34 and 9.10 (2s, 2H, NH2), 8.21 (s, 1H, H-6), 5.80 (d, 1H, H-1', J1'-2' = 6.0 Hz), 5.3-4. 3 (m, 3H, OH-2', OH-3' and OH-5'), 4.21 (t, IH, H-2', J= 5.7 Hz), 3.98 (d, 1H, H-3', J = 5.3 Hz), 3.5-3. 3 (m, 2H, H-5' and H-5"), 1.97 (s, 3H, CH3), 1.12 (s, 3H, CH3).
EXAMPLE 21: PREPARATION OF 0-6-DIPHENYLCARBAMOYL-N-ISOBUTYRYL-9-(2, 3-DI- O ACETYL 5 O-BENZOYL-4-C-METHYL-ß-D-RIBOFURANOSYL) GUANINE (RR) To a suspension of O-6-diphenylcarbamoyl-N2-isobutyrylguanine (1.80 g, 4.33 mmol) in anhydrous toluene (20 mL) was added N, O-bis (trimethylsilyl) acetamide (1.92 mL, 7.9 mmol). The reaction mixture was allowed to warm under reflux for 1 hour. Compound GG (1.55 g, 3.93 mmol) was dissolved in toluene (10 mL) and trimethylsilyltrifluoromethanesulfonate (TMSTf) (915 mL, 4.72 mmol) was added. The mixture was heated under reflux for 30 minutes. The solution was then cooled to room temperature and neutralized with a 5% aqueous sodium hydrogen carbonate solution. The reaction mixture was diluted with ethyl acetate (200 mL). The organic phase was washed with a 5% aqueous sodium hydrogen carbonate solution (150 mL) and with water (2x 150 mL). The organic layer was dried over Na2SO4 and evaporated to dryness. The residue was purified by silica gel column chromatography [eluent: stepwise gradient of diethyl ether (70- 90%) in petroleum ether] to afford pure RR (1.62 g, 55%) as a foam.
EXAMPLE 22: PREPARATION OF 9- (4-C-METHYL-P-D-RIBOFURANOSYL) GUANINE (SS) The title compound can be prepared according to a published procedure from RR (Waga, T.; Nishizaki, T.; et al. Biosci. Biotechnol. Biochem. 1993, 57, 1433-1438).
A solution of RR (1.50 g, mmol) in methanolic ammonia (previously saturated at- 10°C) (20 mL) was stirred at room temperature overnight. The solvent was evaporated under reduced pressure and the residue was partitioned between methylene chloride (60 mL) and water (60 mL). The aqueous layer was washed with methylene chloride (2x 60 mL), concentrated under reduced pressure. The residue was purified by an RP18 column chromatography [eluent water/acetonitrile 95/5] to afford pure SS (380 mg, 60%).
Recrystallization from water gave S as a crystalline solid. Mp > 300 (dec.), UV (H20): lax = 252 nm (E = 14500),'H-NMR (DMSO-d6) : 8 10.64 (s, 1H, NH), 7.95 (s, IH, H-8), 6.45 (sl, 2H, NH2), 5.68 (d, 1H, H-1', J| 2 = 7.45 Hz), 5.31 (d, 1H, OH, OH-2', JOH-2' = 6.8 Hz), 5.17 (t, 1H, OH, OH-5', J = 5.5 Hz), 5.07 (d, 1H, OH-3', JOH-3' = 4.5 Hz), 4.65 (dd, 1H, H-2', J = 7.1 Hz, J = 12.2 Hz), 4.00 (t, 1H, H-3', J3'-2' =J3'-OH'= 4.8 Hz), 3.41 (m, 2H, H-5'and H-5"), 1.12 (s, 3H, CH3); MS (matrix GT): FAB>0 m/z 595 (2M+H) +, 390 (M+G+H) +, 298 (M+H) +, 152 (B+2H) +, FAB<0 m/z 593 (2M-H)-, 296 (M-H)-, 150 (B)-.
EXAMPLE 23: 9-(293-DI-O-ACETYL-5-O-BENZOYL-4-C-METHYL-p-D- RIBOFURANOSYL) ADENINE (TT) A solution of GG (1.10 g, 2.79 mmol) in anhydrous acetonitrile (50 ml) was treated with adenine (452.4 mg, 3.35 mmol) and stannic chloride (SnCl4, 660 µL, 5.58 mmol) and stirred at room temperature overnight. The solution was concentrated under reduced pressure, diluted with chloroform (100 mL) and treated with a cold saturated aqueous solution of NaHCO3 (100 ml). The mixture was filtered on celite, and the precipitate was washed with hot chloroform. The filtrates were combined, washed with water (100 ml) and brine (100 ml), dried (Na2SO4), and evaporated under reduced pressure. The residue was purified by silica gel column chromatography [eluent: stepwise gradient of methanol (3-5%) in dichloromethane] to afford pure TT (977 mg, 77%) as a white foam. IH-NMR (DMSO- d6) : 8 8.31-7. 49 (m, 7H, C6H5CO, H-2 and H-8), 7.37 (1S, 2H, NHz) 6.27 (m, 2H, H-1'and H- 3'), 5.90 (m, 1H, H-2'), 4.60 (d, IH, H-5', J = 11.7 Hz), 4.35 (d, 1H, H-5"), 2.17 (s, 3H, CH3CO2), 2.06 (s, 3H, CH3CO2), 1.42 (s, 3H, CH3).
EXAMPLE 24 : PREPARATIONOF9-(4-C-METHYL-ß-D-BOFURANOSYL) ADENINE (UU) The title compound can be prepared according to a published procedure from TT (Waga, T.; Nishizaki, T.; et al. Biosci. Biotechnol. Biochem. 1993, 57, 1433-1438).
A solution of TT (970 mg, 2.08 mmol) in methanolic ammonia (previously saturated at-10°C) (50 mL) was stirred at room temperature overnight. The solvent was evaporated under reduced pressure and the residue was partitioned between methylene chloride (100 ml) and water (100 ml). The aqueous layer was washed with methylene chloride (2x 100 mL), and concentrated under reduced pressure. The residue was purified by silica gel column chromatography [eluent: stepwise gradient of methanol (10-30%) in ethyl acetate] to afford pure U (554 mg, 95%). Crystallization from methanol/ethyl acetate gave UU as a white solid. Mp: 96-97 (dec.) ;'H-NMR (DMSO-d6): 8 8.33 (s, 1H, H-2), 8.13 (s, 1H, H-8), 7.36 (brs, 2H, NH2), 5.84 (d, 1H, H-l', Jl-2'= 7.4 Hz), 5.69 (dd, 1H, OH-5', J = 4.2 Hz and J = 7.8 Hz), 5.33 (d, 1H, OH-2', J = 6. 6 Hz), 5.13 (d, 1H, OH-3', J = 4.4 Hz), 4.86 (m, 1H, H-2'), 4.04 (t, 1H, H-3'), 3.58-3. 32 (m, 2H, H-5'and H-5"), 1.15 (s, 3H, CH3); MS (matrix GT): FAB>0 m/z 563 (2M+H) +, 374 (M+G+H) +, 282 (M+H) +, 136 (B+2H) +, FAB<0 mlz 561 (2M- H)-, 280 (M-H)-, 134 (B)'.
In a similar manner, the following nucleosides of Formula XVI are prepared, using the appropriate sugar and purine bases. wherein RI, R2, R3, XI, X2, and Y are defined in Table 20.
Alternatively, the following nucleosides of Formula XVIII are prepared, using the appropriate sugar and pyrimidine or purine bases.
wherein Rl, R2, R3, R6, X and Base are defined in Table 21.
Alternatively, the following nucleosides of Formula XIX are prepared, using the appropriate sugar and pyrimidine or purine bases.
wherein R', R2, R6, X and Base are defined in Table 22.
Alternatively, the following nucleosides of Formula XXIV are prepared, using the appropriate sugar and pyrimidine or purine bases. wherein Rl, R2, R6, X, and Base are defined in Table 23.
Alternatively, the following nucleosides of Formula XX are prepared, using the appropriate sugar and pyrimidine or purine bases.
wherein R', R6, R, R8, X, Base, Rl° and R9 are defined in Table 24.
Tables 1-24 set out examples of species within the present invention. When the amino acid appears in the table, it is considered to be a specific and independent disclosure of each of the esters of a, p y or 8 glycine, alanine, valine, leucine, isoleucine, methionine, phenylalanine, tryptophan, proline, serine, threonine, cysteine, tyrosine, asparagine, glutamine, aspartate, glutamate, lysine, arginine and histidine in the D and L-configurations.
When the term acyl is used in the tables, it is meant to be a specific and independent disclosure of any of the acyl groups as defined herein, including but not limited to acetyl, trifluoroacetyl, methylacetyl, cyclopropylacetyl, cyclopropylcarboxy, propionyl, butyryl, hexanoyl, heptanoyl, octanoyl, neo-heptanoyl, phenylacetyl, diphenylacetyl, a- trifluoromethyl-phenylacetyl, bromoacetyl, 4-chloro-benzeneacetyl, 2-chloro-2, 2- diphenylacetyl, 2-chloro-2-phenylacetyl, trimethylacetyl, chlorodifluoroacetyl, perfluoroacetyl, fluoroacetyl, bromodifluoroacetyl, 2-thiopheneacetyl, tert-butylacetyl, <BR> <BR> <BR> <BR> trichloroacetyl, monochloro-acetyl, dichloroacetyl, methoxybenzoyl, 2-bromo-propionyl, decanol, n-pentadecanoyl, stearyl, 3-cyclopentyl-propionyl, 1-benzene-carboxyl, pivaloyl acetyl, 1-adamantane-carboxyl, cyclohexane-carboxyl, 2, 6-pyridinedicarboxyl, cyclopropane- carboxyl, cyclobutane-carboxyl, 4-methylbenzoyl, crotonyl, 1-methyl-lH-indazole-3- carbonyl, 2-propenyl, isovaleryl, 4-phenylbenzoyl.
F. Biological Assays Compounds can exhibit anti-flavivirus or pestivirus activity by inhibiting flavivirus or pestivirus polymerase, by inhibiting other enzymes needed in the replication cycle, or by other pathways.
Phosphorylation Assay of Nucleoside to Active Triphosphate To determine the cellular metabolism of the compounds, HepG2 cells were obtained from the American Type Culture Collection (Rockville, MD), and were grown in 225 cm2 tissue culture flasks in minimal essential medium supplemented with non-essential amino acids, 1% penicillin-streptomycin. The medium was renewed every three days, and the cells were subcultured once a week. After detachment of the adherent monolayer with a 10 minute exposure to 30 mL of trypsin-EDTA and three consecutive washes with medium, confluent HepG2 cells were seeded at a density of 2.5 x 106 cells per well in a 6-well plate and exposed to 10 elm of [3H] labeled active compound (500 dpm/pmol) for the specified time periods.
The cells were maintained at 37°C under a 5% C02 atmosphere. At the selected time points, the cells were washed three times with ice-cold phosphate-buffered saline (PBS).
Intracellular active compound and its respective metabolites were extracted by incubating the cell pellet overnight at-20°C with 60% methanol followed by extraction with an additional 20 pL of cold methanol for one hour in an ice bath. The extracts were then combined, dried under gentle filtered air flow and stored at-20°C until HPLC analysis.
Bioavailability Assay in Cynomolgus Monkeys Within 1 week prior to the study initiation, the cynomolgus monkey was surgically implanted with a chronic venous catheter and subcutaneous venous access port (VAP) to facilitate blood collection and underwent a physical examination including hematology and serum chemistry evaluations and the body weight was recorded. Each monkey (six total) receives approximately 250 pCi of 3H activity with each dose of active compound at a dose level of 10 mg/kg at a dose concentration of 5 mg/mL, either via an intravenous bolus (3 monkeys, IV), or via oral gavage (3 monkeys, PO). Each dosing syringe was weighed before dosing to gravimetrically determine the quantity of formulation administered. Urine samples were collected via pan catch at the designated intervals (approximately 18-0 hours pre-dose, 0-4,4-8 and 8-12 hours post-dosage) and processed. Blood samples were collected as well (pre-dose, 0.25, 0.5, 1, 2,3, 6,8, 12 and 24 hours post-dosage) via the chronic venous
catheter and VAP or from a peripheral vessel if the chronic venous catheter procedure should not be possible. The blood and urine samples were analyzed for the maximum concentration (Cma,), time when the maximum concentration was achieved (TmaX), area under the curve (AUC), half life of the dosage concentration (T,/2), clearance (CL), steady state volume and distribution (Vss) and bioavailability (F).
Bone Marrow Toxicity Assay Human bone marrow cells were collected from normal healthy volunteers and the mononuclear population were separated by Ficoll-Hypaque gradient centrifugation as described previously by Sommadossi J-P, Carlisle R. Antimicrobial Agents and Chemotherapy 1987; 31: 452-454; and Sommadossi J-P, Schinazi RF, et al. Biochemical Pharmacology 1992; 44: 1921-1925. The culture assays for CFU-GM and BFU-E were performed using a bilayer soft agar or methylcellulose method. Drugs were diluted in tissue culture medium and filtered. After 14 to 18 days at 37°C in a humidified atmosphere of 5% C02 in air, colonies of greater than 50 cells were counted using an inverted microscope. The results are presented as the percent inhibition of colony formation in the presence of drug compared to solvent control cultures.
Mitochondria Toxicity Assay HepG2 cells were cultured in 12-well plates as described above and exposed to various concentrations of drugs as taught by Pan-Zhou X-R, Cui L, et al. Antimicrob. Agents Chemother. 2000; 44: 496-503. Lactic acid levels in the culture medium after 4 day drug exposure were measured using a Boehringer lactic acid assay kit. Lactic acid levels were normalized by cell number as measured by hemocytometer count.
Cytotoxicity Assay Cells were seeded at a rate of between 5 x 103 and 5 x 104/well into 96-well plates in growth medium overnight at 37°C in a humidified C02 (5%) atmosphere. New growth medium containing serial dilutions of the drugs was then added. After incubation for 4 days, cultures were fixed in 50% TCA and stained with sulforhodamineB. The optical density was read at 550 nm. The cytotoxic concentration was expressed as the concentration required to reduce the cell number by 50% (CCso).
Cell Protection Assay (CPA) The assay was performed essentially as described by Baginski, S. G.; Pevear, D. C.; et al. PNAS USA 2000,97 (14), 7981-7986. MDBK cells (ATCC) were seeded onto 96-well culture plates (4,000 cells per well) 24 hours before use. After infection with BVDV (strain NADL, ATCC) at a multiplicity of infection (MOI) of 0.02 plaque forming units (PFU) per cell, serial dilutions of test compounds were added to both infected and uninfected cells in a final concentration of 0.5% DMSO in growth medium. Each dilution was tested in quadruplicate. Cell densities and virus inocula were adjusted to ensure continuous cell growth throughout the experiment and to achieve more than 90% virus-induced cell destruction in the untreated controls after four days post-infection. After four days, plates were fixed with 50% TCA and stained with sulforhodamine B. The optical density of the wells was read in a microplate reader at 550 nm. The 50% effective concentration (ECso) values were defined as the compound concentration that achieved 50% reduction of cytopathic effect of the virus.
Plaque Reduction Assay For each compound the effective concentration was determined in duplicate 24-well plates by plaque reduction assays. Cell monolayers were infected with 100 PFU/well of virus. Then, serial dilutions of test compounds in MEM supplemented with 2% inactivated serum and 0.75% of methyl cellulose were added to the monolayers. Cultures were further incubated at 37°C for 3 days, then fixed with 50% ethanol and 0.8% Crystal Violet, washed and air-dried. Then plaques were counted to determine the concentration to obtain 90% virus suppression.
Yield Reduction Assay For each compound the concentration to obtain a 6-log reduction in viral load was determined in duplicate 24-well plates by yield reduction assays. The assay was performed as described by Baginski, S. G.; Pevear, D. C.; et al. PNAS USA 2000,97 (14), 7981-7986, with minor modifications. Briefly, MDBK cells were seeded onto 24-well plates (2 x 105 cells per well) 24 hours before infection with BVDV (NADL strain) at a multiplicity of infection (MOI) of 0.1 PFU per cell. Serial dilutions of test compounds were added to cells in a final concentration of 0.5% DMSO in growth medium. Each dilution was tested in triplicate. After three days, cell cultures (cell monolayers and supernatants) were lysed by
three freeze-thaw cycles, and virus yield was quantified by plaque assay. Briefly, MDBK cells were seeded onto 6-well plates (5 x 105 cells per well) 24 h before use. Cells were inoculated with 0.2 mL of test lysates for 1 hour, washed and overlaid with 0.5% agarose in growth medium. After 3 days, cell monolayers were fixed with 3.5% formaldehyde and stained with 1% crystal violet (w/v in 50% ethanol) to visualize plaques. The plaques were counted to determine the concentration to obtain a 6-log reduction in viral load.
EXAMPLE 25 : ANTIVIRAL POTENCY OF TEST COMPOUNDS IN A CELL BASED ASSAY The titer of BVDB (Logl0 units/ml) were identified after treatment of infected MDBK cells with increasing concentrations of four test compounds. Ribavirin was used as a standard. This data is shown in Figure 11. The graph shows the antiviral potency of these compounds.
EXAMPLE 26: CELLULAR PHARMACOLOGY OF 2'-C-METHYL-CYTIDINE-3'-O-L-VALINE ESTER (VAL-MCYD) Phosphorylation Assay of Nucleoside to Active Triphosphate To determine the cellular metabolism of the compounds, HepG2 cells were obtained from the American Type Culture Collection (Rockville, MD), and were grown in 225 cm2 tissue culture flasks in minimal essential medium supplemented with non-essential amino acids, 1% penicillin-streptomycin. The medium was renewed every three days, and the cells were subcultured once a week. After detachment of the adherent monolayer with a 10 minute exposure to 30 mL of trypsin-EDTA and three consecutive washes with medium, confluent HepG2 cells were seeded at a density of 2.5 x 106 cells per well in a 6-well plate and exposed to 10 pM of [3H] labeled active compound (500 dpm/pmol) for the specified time periods.
The cells were maintained at 37°C under a 5% C02 atmosphere. At the selected time points, the cells were washed three times with ice-cold phosphate-buffered saline (PBS).
Intracellular active compound and its respective metabolites were extracted by incubating the cell pellet overnight at-20°C with 60% methanol followed by extraction with an additional 20 pL of cold methanol for one hour in an ice bath. The extracts were then combined, dried under gentle filtered air flow and stored at-20°C until HPLC analysis.
Antiviral nucleosides and nucleoside analogs were generally converted into the active metabolite, the 5'-triphosphate (TP) derivatives by intracellular kinases. The nucleoside-TPs then exert their antiviral effect by inhibiting the viral polymerase during virus replication. In primary human hepatocyte cultures, in a human hepatoma cell line (HepG2), and in a bovine kidney cell line (MDBK), mCyd was converted into a major metabolite, 2'-C-methyl- cytidine-5'-triphosphate (mCyd-TP), along with smaller amounts of a uridine 5'-triphosphate derivative, 2'-C-methyl-uridine-5'-triphosphate (mUrd-TP). mCyd-TP is inhibitory when tested in vitro against the BVDV replication enzyme, the NS5B RNA dependent RNA polymerase, and is thought to be responsible for the antiviral activity of mCyd.
The cellular metabolism of mCyd was examined using MDBK cells, HepG2 cells and human primary hepatocytes exposed to 10 pM [3H]-mCyd. High-pressure liquid chromatography (HPLC) analysis demonstrated that mCyd was phosphorylated in all three cell types, with mCyd-TP being the predominant metabolite after 24 h. The metabolic profile obtained over a 48-hour exposure of human hepatoma HepG2 cells to 10 pM [3H]-mCyd was tested. In HepG2 cells, levels of mCyd-TP peaked at 41.5 13.4 tM after 24 hours (see Table 25) and fell slowly thereafter. In primary human hepatocytes, the peak mCyd-TP concentration at 24 hours was 4 fold lower at 10.7 6. 7 J. M. MDBK bovine kidney cells yielded intermediate levels of mCyd-TP (30.1 6. 9 pM at 24 hours).
Exposure of hepatocytes to mCyd led to production of a second 5'-triphosphate derivative, mUrd-TP. In HepG2 cells exposed to 10 µM [3H]-mCyd, the mUrd-TP level reached 1.9 1.6 µM at 24 hours, compared to 8.1 3.4 µM in MDBK cells and 3.2 2.0 µM in primary human hepatocytes. While MDBK and HepG2 cells produced comparable total amounts of phosphorylated species (approximately 43 versus 47 uM, respectively) at 24h, mUrd-TP comprised 19% of the total product in MDBK cells versus only 4% in HepG2 cells. mUrd-TP concentration increased steadily over time, however reached a plateau or declined after 24 hours.
Table 25: Activation of mCyd (10 uM) in Heoatocvtes and MDBK Cells Metabolite (M) Cellsa n mCyd-MP mUrd-MP mCyd-DP mUrd-DP mCyd-TP mUrd-TP HepG2 6 ND ND 3.7~2.1 ND 41.5~ 1.9~1. 6 13.4 Human 5 ND ND 1.15~1.1 0.26~0. 4 10. 76. 7 3. 22. 0 Primary C Hepatocytes MDBK 7 4. 2 + 2. 7 0. 76 + 30. 1 6. 9 8. 1 3. 4 Bovine 0.95 Kidney Cells
a. Cells were incubated for 24 hours with [H]-mCyd, specific activity: HepG2 assay = 0.5 Ci/mmol ; human and monkey hepatocyte assay = 1. 0 Ci/mmol. b. The concentrations of metabolites were determined as pmoles per million cells. One pmole per million cells is roughly equivalent to I u. M.
ND, not detected.
The apparent intracellular half-life of the mCyd-TP was 13.9 2.2 hours in HepG2 cells and 7.6 0.6 hours in MDBK cells : the data were not suitable for calculating the half life of mUrd-TP. Other than the specific differences noted above, the phosphorylation pattern detected in primary human hepatocytes was qualitatively similar to that obtained using HepG2 or MDBK cells.
EXAMPLE 27 : CELL CYTOTOXICITY Mitochondria Toxicity Assay HepG2 cells were cultured in 12-well plates as described above and exposed to various concentrations of drugs as taught by Pan-Zhou X-R, Cui L, et al.. Antimicrob. Agents Chemother. 2000; 44: 496-503. Lactic acid levels in the culture medium after 4 day drug exposure were measured using a Boehringer lactic acid assay kit. Lactic acid levels were normalized by cell number as measured by hemocytometer count.
Cytotoxicity Assays Cells were seeded at a rate of between 5 x 103 and 5 x 104/well into 96-well plates in growth medium overnight at 37°C in a humidified C02 (5%) atmosphere. New growth medium containing serial dilutions of the drugs was then added. After incubation for 4 days,
cultures were fixed in 50% TCA and stained with sulforhodamineB. The optical density was read at 550 nm. The cytotoxic concentration was expressed as the concentration required to reduce the cell number by 50% (CC50).
Conventional cell proliferation assays were used to assess the cytotoxicity of mCyd and its cellular metabolites in rapidly dividing cells. The inhibitory effect of mCyd was determined to be cytostatic in nature since mCyd showed no toxicity in confluent cells at concentrations far in excess of the corresponding CC50 for a specific cell line. mCyd was not cytotoxic to rapidly growing Huh7 human hepatoma cells or H9c2 rat myocardial cells at the highest concentration tested (CC50 >250 uM). The mCyd CCso values were 132 and 161 uM in BHK-21 hamster kidney and HepG2 human hepatoma cell lines, respectively. The CCso for mCyd in HepG2 cells increased to 200 uM when the cells were grown on collagen-coated plates for 4 or 10 days. For comparison, CC50 values of 35-36 pM were derived when ribavirin was tested in HepG2 and Huh7 cells. In the MDBK bovine kidney cells used for BVDV antiviral studies, the CC50 of mCyd was 36 pM. A similar CC50 value (34 pM) was determined for mCyd against MT-4 human T-lymphocyte cells. In addition, mCyd was mostly either non-cytotoxic or weakly cytotoxic (CCso >50 to >200 pM) to numerous other cell lines of human and other mammalian origin, including several human carcinoma cell lines, in testing conducted by the National Institutes of Health (NIH) Antiviral Research and Antimicrobial Chemistry Program. Exceptions to this were rapidly proliferating HFF human foreskin fibroblasts and MEF mouse embryo fibroblasts, where mCyd showed greater cytotoxicity (CCsos 16.9 and 2.4 pM, respectively). Again, mCyd was much less toxic to stationary phase fibroblasts.
The cytotoxic effect of increasing amounts of mCyd on cellular DNA or RNA synthesis was examined in HepG2 cells exposed to [3H]-thymidine or [3H]-uridine. In HepG2 cells, the CCsos of mCyd required to cause 50% reductions in the incorporation of radiolabeled thymidine and uridine into cellular DNA and RNA, were 112 and 186 pM, respectively. The CC50 values determined for ribavirin (RBV) for DNA and RNA synthesis, respectively, were 3.16 and 6. 85 1M. These values generally reflect the CC50s of 161 and 36 pM determined for mCyd and RBV, respectively, in conventional cell proliferation cytotoxicity assays. To assess the incorporation of mCyd into cellular RNA and DNA, HepG2 cells were exposed to 10 uM [3H]-mCyd or control nucleosides (specific activity 5. 6 - 8. 0 Ci/mmole, labeled in the base) for 30 hours. Labeled cellular RNA or DNA species were separately isolated and incorporation was determined by scintillation counting.
Exposure of HepG2 cells to mCyd resulted in very low levels of incorporation of the ribonucleoside analog into either cellular DNA or RNA (0. 0013-0. 0014 pmole/pg of nucleic acid). These levels were similar to the 0.0009 and 0.0013 pmole/pg values determined for the incorporation of ZDV and ddC, respectively, into RNA: since these deoxynucleosides were not expected to incorporate into RNA, these levels likely reflect the assay background.
The incorporation of ZDV and ddC into DNA was significantly higher (0.103 and 0.0055 pmole/µg, respectively). Ribavirin (RBV) incorporated into both DNA and RNA at levels 10-fold higher than mCyd.
Table 26a: Cellular Nucleic Acid Synthesis and Incorporation Studies in HepG2 Cells (10
uM Drug and Nucleoside Controls) CCso (M) Incorporated drug amount Compound DNA RNA pmole/µg DNA pmole/µg RNA ([3H]Thymidine) ([3H]Uridine) mCyd 112. 3 34. 5 186. 1 ~28.2 0. 0013 0. 0008a 0. 0014 0. 0008a ZDV nd nd 0. 103 i 0. 0123a 0. 0009 0. 0003a ddC nd nd 0.0055b 0.0013b Ribavirin 3. 16 0. 13 6. 85 1. 83 0.0120b 0.0132c a. Data represent mean of three experiments b. Data represent one experiment c. Data represent mean of two experiments nd, not determined
Table 26b: Cytotoxicity of mCyd in Mammalian Cell Lines Cell Linea n CC50(µM) Huh 7 7 > 250 Hep G2 6 161 19 Hep G2 2 > 200 MDBK 7 36 7 BHK-21 2 132~6 H9c2 2 >250 a. All cytotoxicity testing was done under conditions of rapid cell division b. Cells were grown on collagen coated plates for 4 or 10 d
Bone Marrow Toxicity Assay Human bone marrow cells were collected from normal healthy volunteers and the mononuclear population were separated by Ficoll-Hypaque gradient centrifugation as described previously by Sommadossi J-P, Carlisle R. Antimicrobial Agents and Chemotherapy 1987; 31: 452-454; and Sommadossi J-P, Schinazi RF, et al. Biochemical Pharmacology 1992 ; 44: 1921-1925. The culture assays for CFU-GM and BFU-E were performed using a bilayer soft agar or methylcellulose method. Drugs were diluted in tissue culture medium and filtered. After 14 to 18 days at 37°C in a humidified atmosphere of 5% C02 in air, colonies of greater than 50 cells were counted using an inverted microscope. The results are presented as the percent inhibition of colony formation in the presence of drug compared to solvent control cultures.
Cell Protection Assay (CPA) The assay was performed essentially as described by Baginski, S. G.; Pevear, D. C.; et al. PNAS USA 2000,97 (14), 7981-7986. MDBK cells (ATCC) were seeded onto 96-well culture plates (4,000 cells per well) 24 hours before use. After infection with BVDV (strain NADL, ATCC) at a multiplicity of infection (MOI) of 0.02 plaque forming units (PFU) per cell, serial dilutions of test compounds were added to both infected and uninfected cells in a final concentration of 0.5% DMSO in growth medium. Each dilution was tested in quadruplicate. Cell densities and virus inocula were adjusted to ensure continuous cell growth throughout the experiment and to achieve more than 90% virus-induced cell destruction in the untreated controls after four days post-infection. After four days, plates were fixed with 50% TCA and stained with sulforhodamine B. The optical density of the wells was read in a microplate reader at 550 nm. The 50% effective concentration (ECso) values were defined as the compound concentration that achieved 50% reduction of cytopathic effect of the virus.
The myelosuppressive effects of certain nucleoside analogs have highlighted the need to test for potential effects of investigational drugs on the growth of human bone marrow progenitor cells in clonogenic assays. In particular, anemia and neutropenia are the most common drug-related clinical toxicities associated with the anti-HIV drug zidovudine (ZDV) or the ribavirin (RBV) component of the standard of care combination therapy used for HCV treatment. These toxicities have been modeled in an in vitro assay that employed bone
marrow cells obtained from healthy volunteers (Sommadossi J-P, Carlisle R. Antimicrob.
Agents Chemother. 1987; 31 (3): 452-454). ZDV has been previously shown to directly inhibit human granulocyte-macrophage colony-forming (CFU-GM) and erythroid burst-forming M in this model (BFU-E) activity at clinically relevant concentrations of 1-2 (Berman E, et al.
Blood 1989; 74 (4): 1281-1286; Yoshida Y, Yoshida C. AIDS Res. Hum. Retroviruses 1990; 6 (7): 929-932.; Lerza R, et al. Exp. Hematol. 1997; 25 (3): 252-255; Dornsife RE, Averett DR. Antimicrob. Agents Chemother. 1996 ; 40 (2): 514-519; Kurtzberg J, Carter SG. Exp.
Hematol. 1990; 18 (10): 1094-1096; Weinberg RS, et al. Mt. Sinai J. Med. 1998; 65 (1) : 5-13).
Using human bone marrow clonogenic assays, the CCso values of mCyd in CFU-GM and BFU-E were 14.1 4.5 and 13.9 3.2 ut (see Table 27). mCyd was significantly less toxic to bone marrow cells than both ZDV and RBV (Table 27).
Table 27: Bone Marrow Toxicity of mCyd in Granulocyte Macrophage Progenitor and Erythrocyte Precursor Cells CFU-GMa BFU-Ea Compound CCso (LM) CC50 (gM) mCyd 14. 1 i 4. 5 pM 13. 9 i 3. 2 ZDV 0. 89 t 0. 47 0. 35 i 0. 28 RBV 7.49~2.20 0.99~0. 24 a. Data from 3 independent experiments for RBV and 5-8 independent experiments for mCyd and ZDV. All experiments were done in triplicate.
Effect on Mitochondrial Function Antiviral nucleoside analogs approved for HIV therapy such as ZDV, stavudine (d4T), didanosine (ddl), and zalcitabine (ddC) have been occasionally associated with clinically limiting delayed toxicities such as peripheral neuropathy, myopathy, and pancreatitis (Browne MJ, et al. J. Infect. Dis. 1993; 167 (1) : 21-29; Fischl MA, et al. Ann.
Intern. Med. 1993; 18 (10): 762-769.; Richman DD, et al. N. Engl. J. Med. 1987; 317 (4): 192- 197; Yarchoan R, et al. Lancet 1990; 336 (8714): 526-529). These clinical adverse events have been attributed by some experts to inhibition of mitochondrial function due to reduction in mitochondrial DNA (mtDNA) content and nucleoside analog incorporation into mtDNA. In addition, one particular nucleoside analog, fialuridine (1,-2'-deoxy-2'-fluoro-1-ß-D- arabinofuranosyl-5-iodo-uracil; FIAU), caused hepatic failure, pancreatitis, neuropathy, myopathy and lactic acidosis due to direct mitochondrial toxicity (McKenzie R, et al. N.
Engl. J. Med. 1995; 333 (17): 1099-1105). Drug-associated increases in lactic acid production can be considered a marker of impaired mitochondrial function or oxidative phosphorylation.
(Colacino, J. M. Antiviral Res. 1996 29 (2-3): 125-39).
To assess the potential of mCyd to produce mitochondrial toxicity, several in vitro studies were conducted using the human hepatoma cell lines HepG2 or Huh7. These studies included analysis of lactic acid production, mtDNA content, and determination of changes in morphology (e. g., loss of cristae, matrix dissolution and swelling, and lipid droplet formation) of mitochondrial ultrastructure.
The effects of mCyd on mitochondria are presented in Table 28. No differences were observed in lactic acid production in mCyd-treated cells versus untreated cells at up to 50 LM mCyd in Huh7 cells orlO uM mCyd in HepG2 cells. A modest (38%) increase in lactic acid production was seen in HepG2 cells treated with 50 pM mCyd. The significance of this finding is unclear, particularly since mCyd is unlikely to attain a plasma concentration of 50 ZM in the clinic. For comparison, lactic acid production increases by 100% over control cells in cells treated with 10 p. M FIAU (Cui L, Yoon, et al. J. Clin. Invest. 1995; 95: 555-563).
Exposure of HepG2 cells to mCyd for 6 or 14 days at concentrations up to 50 uM had no negative effect on mitochondrial DNA content compared to a 56 or 80% reduction in ddC- treated cells, respectively.
Following M mCyd, the ultrastructure of HepG2 cells, and inO 14 days of exposure to 10 particular mitochondria, was examined by transmission electron microscopy. No changes in cell architecture, or in mitochondrial number or morphology (including cristae), were observed in the majority of cells. In 17% of the cells, 1 to 2 mitochondria out of an average of 25 per cell appeared enlarged. Such minor changes would be unlikely to have any significant impact on mitochondrial function. ddC-treated cells showed abnormal mitochondrial morphology with loss of cristae, and the accumulation of fat droplets. (Medina, D. J. , C. H. Tsai, et al. Antimicrob. Agents Chemother. 1994 38 (8): 1824-8; Lewis W, et al.
J. Clin. Invest. 1992; 89 (4): 1354-1360., Lewis, L. D. , F. M. Hamzeh, et al. Antimicrob. Agents Chemother. 1992 36 (9): 2061-5). Table 28: Effect of mCyd on Hepatocyte Proliferation, Mitochondrial Function, and Morphology in HepG2 Cells L-Lactate mtDNA/nuclear DNA Electron Microscopy (% of Controla) (% of Control) Agent Cone HepG2 Huh7 6 day 14 day Lipid Mito. Morphol. Treatment Droplet (µM) Cells Cells Treatment Form. Cont. 0 100 100 100 100 Negative Normal mCyd 10 98. 6 7.3 98.0 12. 3 117.3 17.5 99.7 23.9 Negative Normal 50 138. 0 8. 9 97. 1+10.1 158.2 17. 5 83.0 15. 5 nd nd ddC 1 nd nd 44. 3~9. 3 19.6 ~8. 2 nd nd 10 nd nd nd nd Positive Loss of Cristae
Effect on Human DNA Polymerases cr, ß, and r The cellular DNA polymerases are responsible for normal nuclear and mitochondrial DNA synthesis and repair. Nucleoside analog triphosphates are potential inhibitors of DNA polymerases and hence could disrupt critical cell functions. In particular, the inhibition of human polymerase y, the enzyme responsible for mitochondrial DNA synthesis, has been linked to defects in mitochondrial function (Lewis, W. , E. S. Levine, et al. Proceedings of the National Academy of Sciences, USA 1996 93 (8): 3592-7. ). Experiments were undertaken to determine if mCyd-TP inhibited human DNA polymerases. As shown in Table 29 mCyd-TP was not a substrate for human DNA polymerases a, ß, or y. Even 1 mM mCyd-TP failed to inhibit these enzymes by 50% in the majority of replicate assays and ICso values could only be determined to be in excess of 880-1000 uM. In contrast, ddC was a potent inhibitor of all three human DNA polymerases and of polymerases (3 and y in particular (IC50s of 4.8 and 2.7 uM, respectively). Potent inhibition was also seen for the control drug, actinomycin D, a known inhibitor of DNA-dependent-DNA polymerases.
Table 29: Inhibition of Human Polymerases by mCyd-Triphosphate IC50 (µM) mCyd-TPa ddC-TPb Act.Da Polα >1000 78~23.4 5.8~3.1 Potp >883. 3165 4. 8+1 7. 9+3 Pol y 929. 3100 2. 7~1 15.5~4
a. Mean S. D. from 4 data sets b. Mean S. D. from 2 data sets a. HepG2 or huh7 cells were treated with compounds for 4 days, data represent at least three independent experiments b. HepG2 cells were treated with compounds for 6 and 14 days, data represents at least three independent experiments c. HepG2 cells were treated with compounds for 14 days d. 17% cells (11 of 64) contained 1 or 2 enlarged mitochondria out of 25 in two independent experiments nd, not determined EXAMPLE 28 : IN VITRO ANTIVIRAL ACTIVITY AGAINST BVDV Compounds can exhibit anti-flavivirus or pestivirus activity by inhibiting flavivirus or pestivirus polymerase, by inhibiting other enzymes needed in the replication cycle, or by other pathways.
Plaque Reduction Assay For each compound the effective concentration was determined in duplicate 24-well plates by plaque reduction assays. Cell monolayers were infected with 100 PFU/well of virus. Then, serial dilutions of test compounds in MEM supplemented with 2% inactivated serum and 0.75% of methyl cellulose were added to the monolayers. Cultures were further incubated at 37°C for 3 days, then fixed with 50% ethanol and 0.8% Crystal Violet, washed and air-dried. Then plaques were counted to determine the concentration to obtain 90% virus suppression.
Yield Reduction Assay For each compound the concentration to obtain a 6-log reduction in viral load was determined in duplicate 24-well plates by yield reduction assays. The assay was performed
as described by Baginski, S. G.; Pevear, D. C.; Seipel, M.; et al. PNAS USA 2000,97 (14), 7981-7986, with minor modifications. Briefly, MDBK cells were seeded onto 24-well plates (2 x 105 cells per well) 24 hours before infection with BVDV (NADL strain) at a multiplicity of infection (MOI) of 0.1 PFU per cell. Serial dilutions of test compounds were added to cells in a final concentration of 0.5% DMSO in growth medium. Each dilution was tested in triplicate. After three days, cell cultures (cell monolayers and supernatants) were lysed by three freeze-thaw cycles, and virus yield was quantified by plaque assay. Briefly, MDBK cells were seeded onto 6-well plates (5 x 105 cells per well) 24 h before use. Cells were inoculated with 0.2 mL of test lysates for 1 hour, washed and overlaid with 0.5% agarose in growth medium. After 3 days, cell monolayers were fixed with 3.5% formaldehyde and stained with 1% crystal violet (w/v in 50% ethanol) to visualize plaques. The plaques were counted to determine the concentration to obtain a 6-log reduction in viral load.
Studies on the antiviral activity of mCyd in cultured cells were conducted. The primary assay used to determine mCyd antiviral potency was a BVDV-based cell-protection assay (CPA). This assay measures the ability of mCyd to protect growing MDBK bovine kidney cells from destruction by a cytopathic NADL strain of BVDV. The cytotoxicity of the test drug on uninfected cells was measured in parallel. The antiviral activities of mCyd and ribavirin in the CPA are compared in Table 30a. mCyd effectively protected de novo- infected MDBK cells in a concentration-dependent manner with an EC50 = 0.67 0. 22 uM (Table 30a). mCyd afforded complete cytoprotection at concentrations well below the CC50 for mCyd in this assay (38 9 pom). In the CPA, as well as in other assays described below, ribavirin showed no clear antiviral effect: significant (50% or more) cell protection was not achieved in most assays as the cytotoxicity of ribavirin overlaps and masks the protective effect. Thus, ribavirin gave a CC50 of 4.3 0. 6 uM and an EC50 > 4.3 pM in the CPA.
For Tables 30a-30o below, cell lines utilized include MT-4 for HIV; Vero 76, African green monkey kidney cells for SARS; BHK for Bovine Viral Diarrhea Virus; Sb-1 for poliovirus Sabin type-1; CVB-2, CVB-3, CVB-4, and CVA-9 for Coxsackieviruses B-2, B-3, B-4 and A-9; and REO-1 for double-stranded RNA viruses. Note: BVDV = bovine viral diarrhea virus; YFV = yellow fever virus; DENV = dengue virus; WNV = West Nile virus; CVB-2 = Coxsackie B-2 virus; Sb-1 = Sabin type 1 poliomyelitis virus; and REO = double- stranded RNA Reovirus.
Table 30a : In Vitro Activity of mCyd Against BVDV in the Cell Protection Assay Compound n EC50, µM CC50, µM mCyd 11 0. 67 0. 22 38~9 RBV 3 >4.3 4.3~0. 6
Table 30b: CC50 Test Results for ß-D-2'-C-methyl-cytidine (Compound G), 3'-O-valinyl ester of ß-D-2'-C-methyl-cytidine dihydrochloride salt (Compound M, and P-D-2'- C-methyl-uracil (Compound N) CC50 Compound BVDV YFV DENV 2 WNV CVB-2 Sb-1 REO G 34 2.3 54 95 80 12 11.5 13 M 24 5. 8 82 >100 82 12 14 22 N >100 18 100 >or= 80 >100 55 >100 100 Table 30c. CC50 and EC50 Test Results for ß-D-2'-C-methyl-cytidine (Compound G) CCso CCso CC5o ECso ECso ECso ECso ECso ECso Compound MT-4 Vero BHK Sb-1 CVB-2 CVB-3 CVB-4 CVA-9 REO-1 76 G 34 >100 >100 6 11 9 13 26 13
Table 30d. CC50 and EC50 Test Results for ß-D-2'-C-methyl-adenosine (Compound A) and ß-D-2'-C-methyl-2-amino adenosine (Compound B) CCso CCso CCso ECso EC5o EC50 ECso EC50 EC50 Compound MT-4 Vero BHK Sb-1 CVB-2 CVB-3 CVB-4 CVA-9 REO-1 76 A 4 80 70 10 10 14 13 12 >70 B >100 >100 50 90 75 23 32 39 2 Table 30e. CC_ and EC50 Test Results for ß-D-2'-C-methyl-guanosine (Compound C) and ß-D-2'-C-methyl-6-chloro-guanosine (Compound D) CC50 CC50 CC50 EC50 EC50 EC50 EC50 EC50 EC50 Compound MT-4 Vero BHK Sb-1 CVB-2 CVB-3 CVB-4 CVA-9 REO-1 76 C >100 >100 100 22 30 22 12 46 2 D >100 >100 30 50 25 21 25 37 0. 4
Table 30f. CC50 and EC50 Test Results for 3',5' -di-O-valinyl ester of ß-D-2'-C-methyl- guanosine dihydrochloride salt (Compound E) CC50 CC50 CC50 ECso EC50 ECso EC50 EC50 EC50 Compound MT-4 Vero BHK Sb-1 CVB-2 CVB-3 CVB-4 CVA-9 REO-1 76 E >100 >100 100 30 33 30 35 40 2 Table 30g. CCsn and ECs Test Results for P-D-2'-C-methyl-cytidine (Compound G) CC50 CC50 CC50 EC50 EC50 EC50 EC50 EC50 EC50 Compound MT-4 Vero BHK Sb-1 CVB-2 CVB-3 CVB-4 CVA-9 REO-1 76 G 34 >100 >100 6 11 9 13 26 13
Table 30h. CCso and EC50 Test Results for ß-D-2'-C-ethynyl-adenosine (Compound H) CC50 CC50 CC50 EC50 EC50 EC50 EC50 EC50 EC50 Compound MT-4 Vero BHK Sb-1 CVB-2 CVB-3 CVB-4 CVA-9 REO-1 76 H 4. 6 60 15 1 1.5 1 2 2.5 6 Table 30i. CC50 and EC50 Test Results for ß-D-2'-C-ethynyl-cytidine (Compound I) CC50 CC50 CC5o EC50 EC5o EC50 EC50 EC50 ECso Compound MT-4 Vero BHK Sb-1 CVB-2 CVB-3 CVB-4 CVA-9 REO-1 76 I >or= >100 >100 26 33 33 24 59 >100 100
Table 30i. CC50 and EC50 Test Results for ß-D-2-amino-adenosine (Compound J) Also CC50 CC50 EC50 EC50 EC50 EC50 EC50 EC50 Compound MT-4 Vero BHK Sb-1 CVB-2 CVB-3 CVB-4 CVA-9 REO-1 76 J 50 >100 >100 40 53 55 50 53 >100 Table 30k. CC50 Test Results for ß-D-2'-C-methyl-adenosine (Compound A), ß-D-2'-C- methvl-2-amino adenosine (Compound B), and P-D-2'-C-methyl-2-amino-6- cyclopropyl adenosine(Compound K)
CC50 Compound BVDV YFV DENV WNV CVB-2 Sb-I REO 2 A 4.0 1.2 2.7 2.7 3.6 7 7 >70 B >100 2.1 0. 8 0. 7 0. 3 76 90 2 K >100 18 10 4.9 3.5 >100 >100 9.5 Table 301. CC_ Test Results for ß-D-2'-C-methyl-guanosine (Compound C), ß-D-2'-C- methyl-1-(methyl-2-oxo-2-phenyl ethyl) guanosine (Compound L), and P-D-2'-C-methyl-6- chloro guanosine (Compound D) CC50 Compound BVDV YFV DENV 2 WNV CVB-2 Sb-1 REO >100 3. 5 1. 2 1. 4 0. 6 29 50 2 L >100 12 6 4.4 3 >100 >100 12 D >100 0. 7 1.0 0.7 0.3 25 50 0. 4
Table 30m. CC_ Test Results for 3', 5'-di-O-valinyl ester of ß-D-2'-C-methyl-guanosine dihydrochloride salt (Compound E) Also Compound BVDV YFV DENV 2 WNV CVB-2 Sb-I REO E >100 4. 9 1.0 1.4 1 33 55 2.1 Table 30n. CC50 Test Results for ß-D-2'-C-ethynyl-adenosine (Compound H)
CC50 Compound BVDV YFV DENV 2 WNV CVB-2 Sb-1 REO H 4. 6 0.4 2. 0 1. 1 1 1. 2 0. 7 6 Table 30o. CCsn Test Results for ß-D-2'-C-methyl-cytidine (Compound G), 3'-O-valinyl ester of P-D-2'-C-methy !-cytidine dihydrochtoride satt (Compound M), and ß-D-2'- C-methyl-uracil (Compound N) CCso Compound BVDV YFV DENV 2 WNV CVB-2 Sb-1 REO G 34 2. 3 54 95 80 12 11. 5 13 M 24 5.8 82 >100 82 12 14 22 N >100 18 100 > or= 80 >100 55 >100 100
The overall antiviral potency of mCyd was determined against different strains of BVDV and both cytopathic (cp) and noncytopathic (ncp) biotypes in cell protection assays as well as in plaque reduction and yield reduction assays. The latter assays measure the output of infectious virus from cells and hence provide a stringent test of antiviral efficacy. The different data sets from all three assays show agreement as summarized in Table 31. The range of 50% and 90% effective inhibitory concentration (EC50 and EC90) values for mCyd was 0.3 to 2.8 µM and 0.87 to 4.8 pM, respectively.
In the BVDV yield reduction assay, subcytotoxic concentrations (circa 20 pM) of mCyd suppressed de novo BVDV production by up to 6 logs, to the point where no infectious virus was detected. A 4 logic effective reduction in BVDV production (EC4íoglo or EC99.99) was attained between 6.0 and 13.9 uM mCyd. In contrast, interferon alpha 2b (IFN a2b), although active against BVDV in this assay (EC50 2.6 IU per ml), never gave more than 2 logs of viral reduction, even at 1000 IU per ml. Thus, the antiviral effect of mCyd against BVDV was much greater than that of IFNa2b or RBV.
EXAMPLE 29: : IN VITRO ANTIVIRAL ACTIVITY AGAINST OTHER POSITIVE-STRAND RNA VIRUSES mCyd has been tested for efficacy against positive-strand RNA viruses other than BVDV. Data obtained are summarized in Table 31 and 32. Against flaviruses, mCyd showed modest activity. The composite ECso ranges (in pM) determined from both sites were: West Nile virus (46-97); Yellow Fever virus (9-80); and Dengue Virus (59-95). For
mCyd against the alpha virus, Venezuelan Equine Encephalitis virus, EC50 values were 1.3- 45 uM. mCyd was broadly active against Picornoviruses, such as Polio virus (EC50 = 6 uM), Coxsackie virus (EC50 = 15 pM), Rhinovirus types 5 and 14 (EC50s = <0.1 and 0.6 µg/ml) and Rhinovirus type 2 (EC5o 2-10 µM). mCyd was generally inactive against all RNA and DNA viruses tested except for the positive-strand RNA viruses. mCyd was also found to have no activity against HIV in MT-4 human T lymphocyte cells or HBV in HepG2.2. 15 cells.
Table 31 : In Vitro Antiviral Activity of mCyd Against Plus-Strand RNA Viruses Method of Virus Type Cell n Antiviral Efficacy (pM) Assay Type ECso EC9o ECa n8 Cell BVDV MDBK 11 0. 67 0. 22 Protection NADL cp Assay Yield BVDV MDBK 3 2. 77 + 1. 16 4. 8 + 1. 55 13. 9 + 3. 07 Reduction NADL cp Assay Assay BVDV MDBK 6 0. 30 0. 07 0. 87 0. 18 6. 03 1. 41 New York-1 ncp BVDV MDBK 1 0. 68 1. 73 8. 22 I-NADL cp BVDV MDBK 1 0. 59 1. 49 7. 14 I-N-dlns ncp Plaque BVDV MDBK 3 2. 57 + 0. 35 4. 63 + 0. 72 Reduction NADL cp Assay Cell West Nile Virus BHK 3 63-97 Protection Assay Cell Yellow Fever BHK 1 60-80 Protection Virus 17D Assay DENV-2 BHK 2 95 Cell DENV-4 BHK 59 Protection Assay Polio Virus Plaque VERO 1 6 Reduction Assay Plaque Coxsackie VERO 1 15 Reduction Virus B2 Assay cp, cytopathic virus; ncp noncytopathic virus I-NADL cp and I-N-dIns ncp represent recombinant BVDV viruses Table 32: In Vitro Antiviral Activity. Selectivity, and Cytotoxicity of mCyd
Virus (Cell line)a EC50b(µM) CC50c(µM) WNV (Vero) 46 114-124 YFV (Vero) 9-30 150->200 VEE (Vero) 1. 3-45 >200 HSV-1 (HFF)d >100 >100 HSV-2 (HFF)"100100 VZV (HFF) d >20 67. 8 EBV (Daudi)d 25.5 >50 HCMV (HFF)d 9. 9-15. 6 67-73 MCMV (MEF) >0. 8 2. 4 Influenza A/H1N1 (MDCK) >200 >200 Influenza A/H3N2 (MDCK) >20 45-65 Influenza B (MDCK) >200 55-140 Adenovirus type 1 (A549) >200 >200 Parainfluenza type 3 (MA-104) >200 >200 Rhinovirus type 2 (KB) 2-10 >200 Rhinovirus type 5 (KB) d 0. 6 20-30 Rhinovirus type 14 (HeLa-Ohio) d <0. 1 20->100 RSV type A (MA-104) >200 200 Punta Toro A (LLC-MK2) >200 >200 a. HFF, human foreskin fibroblast ; Daudi, Burkitt's B-cell lymphom ; MDCK, canine kidney cells ; CV-1, African green monkey kidney cells ; KB, human nasopharyngeal carcinoma; MA-104, Rhesus monkey kidney cells ; LLC-MK2, Rhesus monkey kidney cells ; A549, Human lung carcinoma cells ; MEF, mouse embryo fibroblast ; Vero, African green monkey kidney cells ; HeLa, human cervical adenocarcinoma cells. b. EC50 = 50% effective concentration. c. CC50 = 50% cytotoxic concentration. d. Result presented in pg/mL rather than pM.
EXAMPLE 30 : MULTIPLICITY OF INFECTION (MOI) AND ANTIVIRAL EFFICACY The cell protection assay format was used to test the effect of increasing the amount of BVDV virus on the EC50 of mCyd. Increasing the MOI of BVDV in this assay from 0.04 to 0.16, caused the EC50 of mCyd to increase linearly from 0. 5 llM to approximately 2.2 pM.
EXAMPLE 31: VIRAL REBOUND IN MCYD TREATED CELLS The effect of discontinuing treatment with mCyd was tested in MDBK cells persistently infected with a noncytopathic strain (strain I-N-dIns) of BVDV. Upon passaging in cell culture, these cells continuously produce anywhere from 106 to >107 infectious virus particles per ml of media. This virus can be measured by adding culture supernatants from treated MDBK (BVDV) cells to uninfected MDBK cells and counting the number of resultant viral foci after disclosure by immunostaining with a BVDV-specific antibody.
Treatment of a persistently infected cell line with 4 gM mCyd for one cell passage (3 days) reduced the BVDV titer by approximately 3 logic from pretreatment and control cell levels of just under 107 infectious units per ml. At this point, mCyd treatment was discontinued.
Within a single passage, BVDV titers rebounded to untreated control levels of just over 107 infectious units per ml.
EXAMPLE 32: MECHANISM OF ACTION In standard BVDV CPA assays, mCyd treatment results in a marked increase in total cellular RNA content as cells grow, protected from the cytopathic effects of BVDV. This was coupled with a marked decrease in the production of BVDV RNA due to mCyd.
Conversely, in the absence of mCyd, total cellular RNA actually decreases as BVDV RNA rises due to the destruction of the cells by the cytopathic virus. To further test the effect of mCyd on viral and cellular RNAs, the accumulation of intracellular BVDV RNA was monitored in MDBK cells 18-hours post infection (after approximately one cycle of virus replication) using Real Time RT-PCR. In parallel, a cellular housekeeping ribosomal protein mRNA (rig S15 mRNA) was also quantitated by RT-PCR using specific primers. The results showed that mCyd dramatically reduced BVDV RNA levels in de novo-infected MDBK cells with an EC50 of 1.7 uM and an ECgo of 2.3 pM. The maximum viral RNA reduction was 4 log, o at the highest inhibitor concentration tested (125 pM). No effect on the level of the rig S15 cellular mRNA control was observed. Together, the preceding findings suggest that
mCyd inhibits BVDV by specifically interfering with viral genome RNA synthesis without impacting cellular RNA content. This idea is further supported by the observation (Table 26a) that inhibition of RNA synthesis as measured by [3H]-uridine uptake in HepG2 cells requires high concentrations of mCyd (EC50 = 186 pM).
In in vitro studies using purified BVDV NS5B RNA-dependent RNA polymerase (Kao, C. C. , A. M. Del Vecchio, et al. 1999. Virology 253 (1) : 1-7) and synthetic RNA templates, mCyd-TP inhibited RNA synthesis with an IC50 of 0. 74 uM and was a competitive inhibitor of BVDV NS5B RNA-dependent RNA polymerase with respect to the natural CTP substratE. The inhibition constant (K ;) for mCyd-TP was 0.16 pM and the Michaelis-Menten constant (Km) for CTP was 0.03 pM. Inhibition of RNA synthesis by mCyd-TP required the presence of a cognate G residue in the RNA template. The effect of mCyd-TP on RNA synthesis in the absence of CTP was investigated in more detail using a series of short (21mer) synthetic RNA templates containing a single G residue, which was moved progressively along the template. Analysis of the newly synthesized transcripts generated from these templates in the presence of mCyd-TP revealed that RNA elongation continued only as far as the G residue, then stopped (Figure 12). In templates containing more than one G residue, RNA synthesis stopped at the first G residue encountered by the polymerase.
These data strongly suggest that m-Cyd-TP is acting as a non-obligate chain terminator. The mechanism of this apparent chain termination is under further investigation.
EXAMPLE 33: Eradication Of A Persistent Bvdv Infection The ability of mCyd to eradicate a viral infection was tested in MDBK cells persistently infected with a noncytopathic strain of BVDV (strain I-N-dIns). (Vassilev, V. B. and R. O. Donis Virus Res. 2000 69 (2): 95-107. ) Compared to untreated cells, treatment of persistently infected cells with 16 pM mCyd reduced virus production from more than 6 logs of virus per ml to undetectable levels within two cell passages (3 to 4 days per passage). No further virus production was seen upon continued treatment with mCyd through passage 12.
At passages 8,9 and 10 (arrows, Figure 13), a portion of cells was cultured for two further passages in the absence of drug to give enough time for mCyd-TP to decay and virus replication to resume. The culture media from the cells were repeatedly tested for the re- emergence of virus by adding culture supernatants from treated MDBK (BVDV) cells to uninfected MDBK cells and counting the resultant viral foci after disclosure by immunostaining with a BVDV-specific antibody. Although this assay can detect a single
virus particle, no virus emerged from the cells post drug treatment. Thus, treatment with mCyd for 8 or more passages was sufficient to eliminate virus from the persistently infected cells.
EXAMPLE 34: COMBINATION STUDIES WITH INTERFERON ALPHA 2B The first study, performed in MDBK cells persistently infected with the New York-1 (NY-1) strain of BVDV, compared the effect of monotherapy with either mCyd (8 M) or interferon alpha 2b (200 IU/ml), or the two drugs in combination (Figure 14A). In this experiment, 8 llM mCyd alone reduced viral titers by approximately 3.5 log, o after one passage to a level that was maintained for two more passages. Interferon alpha 2b alone was essentially inactive against persistent BVDV infection (approximately 0.1 logic reduction in virus titer) despite being active against de novo BVDV infection. However, the combination of mCyd plus interferon alpha 2b reduced virus to undetectable levels by the second passage and clearly showed better efficacy to either monotherapy.
In a follow up study (Figure 14B) of MDBK cells persistently infected with the I-N- dlns noncytopathic strain of BVDV, mCyd was supplied at fixed doses of 0, 2,4 and 8 pM, while interferon alpha 2b was titrated from 0 to 2,000 IU per ml. Again, interferon alpha 2b was essentially inactive (0.1 log reduction in viral titer), while mCyd alone inhibited BVDV (strain I-N-dIns) propagation in a dose-dependent manner. mCyd at 8 pM reduced virus production by 6.2 logis, to almost background levels.
EXAMPLE 35: RESISTANCE DEVELOPMENT In early cell culture studies, repeated passaging of a cytopathic strain of BVDV in MDBK cells in the presence of mCyd failed to generate resistant mutants, suggesting that the isolation mCyd-resistant BVDV mutants is difficult. However, studies in cell lines persistently infected with noncytopathic forms of BVDV led to the selection of resistant virus upon relatively prolonged treatment with mCyd at suboptimal therapeutic concentrations of drug (2 to 8 IlM, depending on the experiment). In the representative experiment shown in Figure 15A, the virus was no longer detectable after two passages in the presence of 8 uM mCyd, but re-emerged by passage 6. The lower titer of the re-emergent virus is apparent from the data: resistant virus typically has a 10 fold or more lower titer than the wild-type virus and was easily suppressed by co-therapy with IntronA (Figure 15A). The phenotype of
the virus that re-emerged was remarkably different from the initial wild-type virus: as shown in Figure 15B, it yielded much smaller foci (typically, 3 to 10 times smaller in diameter then those of the wild-type virus). This phenotype did not change after prolonged passaging in culture in the presence of the inhibitor (at least 72 days), however, it quickly reverted to the wild-type phenotype (large foci) after the discontinuation of the treatment.
RT-PCR sequencing of the resistant mutant was used to identify the mutation responsible for resistance. Sequencing efforts were focused on the NS5B RNA-dependent RNA polymerase region of BVDV, which was assumed to be the likely target for a nucleoside inhibitor. A specific S405T amino-acid substitution was identified at the start of the highly conserved B domain motif of the polymerase. The B domain is part of the polymerase active site and is thought to be involved in nucleoside binding (Lesburg, C. A., M. B. Cable, et al. Nature Structural Biology 1999 6 (10): 937-43). Resistance to nucleosides has been mapped to this domain for other viruses such as HBV (Ono et al, J. Clin. Invest.
2001 Feb; 107 (4): 449-55. ). To confirm that this mutation was responsible for the observed resistance, the mutation was reintroduced into the backbone of a recombinant molecular clone of BVDV. The resulting clone was indistinguishable in phenotypic properties from the isolated mutant virus, confirming that the S405T mutation is responsible for resistance and that the NS5B RNA-dependent RNA polymerase is the molecular target for mCyd. The highly conserved nature of this motif at the nucleotide sequence (Lai, V. C. , C. C. Kao, et al.
J. Virol. 1999 73 (12): 10129-36) and structural level among positive-strand RNA viruses (including HCV) allows a prediction that the equivalent mutation in the HCV NS5B RNA- dependent RNA polymerase would likely be S282T.
S405T mutant BVDV was refractory to mCyd up to the highest concentrations that could be tested (EC50>32 pM), but was also significantly impaired in viability compared to wild-type virus. As noted above, the S405T mutant exhibited a 1-2 loglo lower titer than wild-type. BVDV and produced much smaller viral plaques. In addition, the mutant virus showed a marked reduction in the rate of a single cycle of replication (>1000-fold lower virus titer at 12h), and accumulated to about 100 fold lower levels than the wild-type virus even after 36 h of replication (Figure 15C). The virus also quickly reverted to wild-type virus upon drug withdrawal. Finally, the mutant was also more sensitive (-40 fold) to treatment with IFN alpha 2b than wild-type as shown in Figure 15D.
A second, additional mutation, C446S, was observed upon further passaging of the S405T mutant virus in the presence of drug. This mutation occurs immediately prior to the
essential GDD motif in the C domain of BVDV NSSB RNA-dependent RNA polymerase.
Preliminary studies suggest that a virus bearing both mutations does not replicate significantly better than the S405T mutant, hence the contribution of this mutation to viral fitness remains unclear. Further studies to characterize resistance development are ongoing.
EXAMPLE 36: IN VIVO ANTIVIRAL ACTIVITY OF VAL-MCYD IN AN ANIMAL EFFICACY MODEL Chimpanzees chronically infected with HCV are the most widely accepted animal model of HCV infection in human patients (Lanford, R. E. , C. Bigger, et al. Ilar J. 2001 42 (2): 117-26; Grakoui, A. , H. L. Hanson, et al. Hepatology 2001 33 (3): 489-95). A single in vivo study of the oral administration of val-mCyd in the chimpanzee model of chronic hepatitis C virus infection has been conducted.
HCV genotyping on the five chimpanzees was performed by the Southwest Foundation Primate Center as part of their mandated internal Health and Maintenance Program, designed to ascertain the disease status of all animals in the facility to identify potential safety hazards to employees. The five chimpanzees used in this study exhibited a high HCV titer in a genotyping RT PCR assay that distinguishes genotype 1 HCV from all other genotypes, but does not distinguish genotype la from lb. This indicates that the chimpanzees used in this study were infected with genotype 1 HCV (HCV-1).
Table 33: Summary of Val-mCyd In Vivo Activity Study in the Chimpanzee Model of Chronic HCV Infection Study Description Species Val-mCyd Doses Frequency/Study Endpoints (N) (mg/kg) (n) Route of Administration One-week antiviral Chimpanzee 10 and 20 (2 each) QD x 7 days Serum HCV RNA, serum activity of mCyd in (5) [equivalent to 8.3 chemistries, CBCs, chronically hepatitis C and 16. 6 mpk of general well being, and virus (genotype 1)-free base], and clinical observations infected chimpanzees vehicle control (1) Seven-Day Antiviral Activity Study in the Chimpanzee Model of Chronic Hepatitis C Virus Infection
Four chimpanzees (2 animals per dose group at 10 mg/kg/day or 20 mg/kg/day) received val-mCyd dihydrochloride, freshly dissolved in a flavorful fruit drink vehicle.
These doses were equivalent to 8.3 and 16.6 mg/kg/day ofthe val-mCyd free base, respectively. A fifth animal dosed with vehicle alone provided a placebo control. The study design included three pretreatment bleeds to establish the baseline fluctuation of viral load and three bleeds during the one week of treatment (on days 2,5 and 7 of therapy) to evaluate antiviral efficacy. The analysis was completed at the end of the one-week dosing period, with no further follow up.
HCVRNA Determination Serum levels of HCV RNA throughout the study were determined independently by two clinical hospital laboratories. HCV RNA was assayed using a quantitative RT-PCR nucleic acid amplification test (Roche Amplicor HCV Monitor Test, version 2.0). This assay has a lower limit of detection (LLOD) of 600 IU/mL and a linear range of 600-850,000 IU/mL.
To aid in interpretation of the viral load declines seen during therapy, emphasis was placed on determining (i) the extent of fluctuations in baseline HCV viral load in individual animals, and (ii) the inherent variability and reproducibility of the HCV viral load assay. To address these issues, full viral load data sets obtained from the two laboratories were compared. The results from both sites were found to be closely comparable and affirmed both the stability of the pretreatment HCV viral loads as well as the reliability of the HCV Roche Amplicor assay. To present the most balanced view of the study, the mean values derived by combining both data sets were used to generate the results presented in Figures 16 and 17. Figure 16 presents the averaged data for dose cohorts, while Figure 17 presents the individual animal data. The changes in viral load from baseline seen during therapy for each animal at each site are also summarized in Table 34.
The HCV viral load analysis from the two sites revealed that pretreatment HCV viral loads were (i) very similar among all five animals and all 3 dose groups, and (ii) very stable over the 3-week pretreatment period. The mean pretreatment logic viral load and standard deviations among the five individual animals were 5.8 0.1 (site 1) and 5.6 0.1 (site 2).
These data indicate that the c. v. (coefficient of variance) of the assay is only around 2% at both sites. The largest fluctuation in HCV viral load seen in any animal during pretreatment was approximately 0.3 logio.
As seen in Figures 16 and 17, once a day oral delivery of val-mCyd produced a rapid antiviral effect that was not seen for the placebo animal, nor during the pretreatment period.
Viral titers were substantially reduced from baseline after two days of therapy for all animals receiving val-mCyd, and tended to fall further under continued therapy in the two treatment arms. By the end of treatment (day 7), the mean reductions from baseline HCV viral load were 0.83 loglo and 1.05 loglo for the 8.3 and 16.6 mg/kg/day dose groups, respectively. The titer of the placebo animal remained essentially unchanged from baseline during the therapy period.
An analysis of the data from the two quantification sites on the changes in baseline HCV viral load in response to therapy is presented in Table 34. Overall, the two data sets agree well, confirming the reliability of the assay. With the exception of animal 501, the difference in viral load between the two sites was generally 0.3 logic or less, similar to the fluctuation observed during the pretreatment period. For animal 501, the discrepancy was closer to 0.5 logio. The viral load drop seen in response to therapy varied from 0.436 (animal 501, site 1) to 1.514 logio (animal 497, site 2). The latter corresponds to a change in HCV viral load from 535,000 (pretreatment) to 16,500 (day 7) genomes per ml.
Table 34: Summary of Changes in Baseline Logen HCV RNA Viral Load During Therapy Dose Animal ID Site Day 2 Day 5 Day 7 (mpk) 499 0. 00041-0. 11518 0. 14085 2-0.06604 0.10612-0. 16273 8. 3 500 1-1. 15634-0. 40385-0.80507 2-1. 07902-0. 55027-1.06259 8. 3 501 1-0. 25180-0.36179-0. 43610 2-0. 45201-0. 71254-0.90034 16. 6 497 1-0. 72148-0. 90704-1.27723 2-0.85561-1. 01993-1.51351 16. 6 498 1-0. 29472-0.28139-0. 60304 2-0.65846-0. 55966-0.69138 Exposure of Chimpanzees to mCyd Limited HPLC analyses were perfomed to determine the concentration of mCyd attained in the sera of chimpanzees following dosing with val-mCyd. In sera drawn 1 to 2 hours post dose on days 2 and 5 of dosing, mCyd levels were typically between 2.9 and 12.1
M (750 and 3100 ng/mL, respectively) in treated animals. No mCyd was detected in pretreatment sera or in the placebo control sera. Within 24 hours of the final dose, serum levels of mCyd had fallen to 0.2 to 0.4 pM (50 and 100 ng/mL, respectively). No mUrd was detected in any sera samples although the methodology used has a lower limit of quantification of 0.4 pM (100 ng/mL) for mUrd.
Safety of mCyd in the Chimpanzee Model of Chronic HCVInfection Chimpanzees were monitored by trained veterinarians throughout the study for weight loss, temperature, appetite, and general well being, as well as for blood chemistry profile and CBCs. No adverse events due to drug were noted. The drug appeared to be well tolerated by all four treated animals. All five animals lost some weight during the study and showed some aspartate aminotransferase (AST) elevations, but these are normal occurrences related to sedation procedures used, rather than study drug. A single animal experienced an alanine aminotransferase (ALT) flare in the pretreatment period prior to the start of dosing, but the ALT levels diminished during treatment. Thus, this isolated ALT event was not attributable to drug.
EXAMPLE 37 : IN VITRO METABOLISM Studies were conducted to determine the stability of val-mCyd and mCyd in human plasma. Val-mCyd was incubated in human plasma at 0,21 or 37°C and samples analyzed at various time points up to 10 hours (Figure 18). At 37°C, val-mCyd was effectively converted to mCyd, with only 2% of the input val-mCyd remaining after 10 hours. The in vitro half-life of val-mCyd in human plasma at 37°C was 1.81 hours. In studies of the in vitro stability of mCyd in human plasma, or upon treatment with a crude preparation enriched in human cytidine/deoxycytidine deaminase enzymes, mCyd remained essentially unchanged and no deamination to the uridine derivative of mCyd (mUrd) occurred after incubation at 37°C.
Only in rhesus and cynomologus monkey plasma was limited deamination observed.
Incubation of mCyd at 37°C in cynomologus monkey plasma yielded 6.7 and 13.0% of mUrd deamination product after 24 and 48 hours, respectively, under conditions where control cytidine analogs were extensively deaminated.
In addition to the TP derivatives of mCyd and mUrd, minor amounts of mCyd-5'- diphosphate, mCyd-DP, roughly 10% the amount of the corresponding TP, were seen in all three cell types. Lesser amounts of mUrd-DP were detected only in two cell types (primary
human hepatocytes and MDBK cells). No monophosphate (MP) metabolites were detected in any cell type. There was no trace of any intracellular mUrd and no evidence for the formation of liponucleotide metabolites such as the 5'-diphosphocholine species seen upon the cellular metabolism of other cytidine analogs.
Figure 19 shows the decay profiles of mCyd-TP determined following exposure of HepG2 cells to 10 M [3H]-mCyd for 24 hours. The apparent intracellular half-life of the mCyd-TP was 13.9 2.2 hours in HepG2 cells and 7.6 0.6 hours in MDBK cells : the data were not suitable for calculating the half life of mUrd-TP. The long half life of mCyd-TP in human hepatoma cells supports the notion of once-a-day dosing for val-mCyd in clinical trials for HCV therapy. Phosphorylation of mCyd occurred in a dose-dependent manner up to 50 uM drug in all three cell types, as shown for HepG2 cells in Figure 19C. Other than the specific differences noted above, the phosphorylation pattern detected in primary human hepatocytes was qualitatively similar to that obtained using HepG2 or MDBK cells.
Contribution of mUrd In addition to the intracellular active moiety, mCyd-TP, cells from different species have been shown to produce variable and lesser amounts of a second triphosphate, mUrd-TP, via deamination of intracellular mCyd species. The activity of mUrd-TP against BVDV NS5B RNA-dependent RNA polymerase has not been tested to date but is planned. To date, data from exploratory cell culture studies on the antiviral efficacy and cytotoxicity of mUrd suggest that mUrd (a) is about 10-fold less potent than mCyd against BVDV; (b) has essentially no antiviral activity against a wide spectrum of other viruses; and (c) is negative when tested at high concentrations in a variety of cytotoxicity tests (including bone marrow assays, mitochondrial function assays and incorporation into cellular nucleic acid). Based on these results, it appears that the contribution of mUrd to the overall antiviral activity or cytotoxicity profile of mCyd is likely to be minor. Extensive toxicology coverage for the mUrd metabolite of mCyd exists from subchronic studies conducted with val-mCyd in the monkey.
EXAMPLE 38 : CELLULAR PATHWAYS FOR METABOLIC ACTIVATION The nature of the enzyme responsible for the phosphorylation of mCyd was investigated in substrate competition experiments. Cytidine (Cyd) is a natural substrate of cytosolic uridine-cytidine kinase (UCK), the pyrimidine salvage enzyme responsible for
conversion of Cyd to Cyd-5'-monophosphate (CMP). The intracellular phosphorylation of mCyd to mCyd-TP was reduced in the presence of cytidine or uridine in a dose-dependent fashion with EC50 values of 19.17 4. 67 uM for cytidine and 20.92 7.10 M for uridine.
In contrast, deoxycytidine, a substrate for the enzyme deoxycytidine kinase (dCK), had little effect on the formation of mCyd-TP with an EC50 > 100 IlM. The inhibition of mCyd phosphorylation by both cytidine and uridine, but not deoxycytidine, suggests that mCyd is phosphorylated by the pyrimidine salvage enzyme, uridine-cytidine kinase (Van Rompay, A.
R. , A. Norda, et al. Mol Pharmacol 2001 59 (5): 1181-6). Further studies are required to confirm the proposed role of this kinase in the activation of mCyd.
EXAMPLE 39: PATHWAYS FOR THE CELLULAR BIOSYNTHESIS OF MURD-TP As outlined above, mUrd-TP is a minor metabolite arising to varying extents in cells from different species. mUrd does not originate via extracellular deamination of mCyd since mUrd is not seen in the cell medium which also lacks any deamination activities. The cellular metabolism data are consistent with the idea that mUrd-TP arises via the biotransformation of intracellular mCyd species. Consideration of the known ribonucleoside metabolic pathways suggests that the most likely routes involve deamination of one of two mCyd species by two distinct deamination enzymes: either mCyd-MP by a cytidylate deaminase (such as deoxycytidylate deaminase, dCMPD), or of mCyd by cytidine deaminase (CD). Further phosphorylation steps lead to mUrd-TP. These possibilities are under further investigation.
EXAMPLE 40: CLINICAL EVALUATION OF VAL-MCYD Patients who met eligibility criteria were randomized into the study at Baseline (Day 1), the first day of study drug administration. Each dosing cohort was 12 patients, randomized in a 10: 2 ratio to treatment with drug or matching placebo. Patients visited the study center for protocol evaluations on Days 1,2, 4,8, 11, and 15. After Day 15, study drug was stopped. Thereafter, patients attended follow-up visits on Days 16,17, 22, and 29.
Pharmacokinetic sampling was performed on the first and last days of treatment (Day 1 and Day 15) on all patients, under fasting conditions.
The antiviral effect of val-mCyd was assessed by (i) the proportion of patients with a 1. 0 logic decrease from baseline in HCV RNA level at Day 15, (ii) the time to a 1.0 logo
decrease in serum HCV RNA level, (iii) the change in HCV RNA level from Day 1 to Day 15, (iv) the change in HCV RNA level from Day 1 to Day 29, (v) the proportion of patients who experience return to baseline in serum HCV RNA level by Day 29, and (vi) the relationship of val-mCyd dose to HCV RNA change from Day 1 to Day 15. <BR> <BR> <BR> <BR> <P>Clinical Pharmacokinetics of mCyd after Oral Administration of Escalating Doses of Val-<BR> <BR> <BR> <BR> <BR> <BR> <BR> mCyd Pharmacokinetics were evaluated over a period of 8 h after the first dose on day 1 and after the last dose on day 15, with 24-h trough levels monitored on days 2,4, 8,11 and 16, and a 48-h trough on day 17. Plasma concentrations of mCyd, mUrd and Val-mCyd were measured by a HPLC/MS/MS methodology with a lower limit of quantitation (LOQ) at 20 ng/ml.
The pharmacokinetics of mCyd was analyzed using a non-compartmental approach.
As presented in the tables below, the principal pharmacokinetic parameters were comparable on day 1 and day 15, indicative of no plasma drug accumulation after repeated dosing. The plasma exposure also appears to be a linear function of dose. As shown in the tables below, principal pharmacokinetic parameters of drug exposure (Cmax and AUC) doubled as doses escalated from 50 to 100 mg.
Table 35: Pharmacokinetic parameters of mCyd at 50 mg Parameters Cmax Tmax AUCo-inf t)/2 (ng/ml) (h) (ng/mlxh) (h) Day 1 Mean 428. 1 2. 5 3118. 7 4. 1 SD 175. 5 1. 1 1246. 4 0. 6 CV % 41. 0 43. 2 40. 0 13. 8 Day 15 Mean 362. 7 2. 2 3168. 4 4. 6 SD 165. 7 1. 0 1714. 8 1. 3 CV% 45. 7 46. 9 3 28. 6 Table 36: Pharmacokinetic parameters of mCyd at 100 mg Parameters Cmax Tax AUCo-inf tl, 2 (ng/ml) (h) (ng/mlxh) (h) Day 1 Mean 982.1 2.6 6901.7 4.4 SD 453. 2 1. 0 2445. 7 1. 1 CV % 46. 1 36. 2 35. 4 25. 2 Day 15 Mean 1054. 7 2. 0 7667. 5 4. 2 SD 181. 0 0. 0 1391. 5 0. 5 CV % 17. 2 0. 0 18. 1 11. 7
The mean day 1 and day 15 plasma kinetic profiles of mCyd at 50 and 100 mg are depicted in the Figure 20.
In summary, following oral administration of val-mCyd, the parent compound mCyd was detectable in the plasma of HCV-infected subjects. mCyd exhibits linear plasma pharmacokinetics in these subjects across the two dose levels thus far examined. There was no apparent accumulation of mCyd in subjects'plasma following 15 days of daily dosing at the doses thus far examined. <BR> <BR> <BR> <BR> <BR> <P>Antiviral Activity of mCyd after Oral Administration of Escalating Doses of Val-mCyd Starting at 50 mg/day for 15 Days in HCV-Infected Patients Serum HCV RNA level were determined with the use of the Amplicor HCV Monitor assay v2.0 (Roche Molecular Systems, Branchburg, NJ, USA), which utilizes polymerase chain reaction (PCR) methods. The lower limit of quantification (LLOQ) with this assay was estimated to be approximately 600 IU/mL and the upper limit of quantification (ULOQ) with this assay was estimated to be approximately 500,000 IU/mL.
Serum samples for HCV RNA were obtained at screening (Day-42 to-7) to determine eligibility for the study. The Screening serum HCV RNA values must be 5 logo IU/mL by the Amplicor HBV Monitor assay at the central study laboratory.
During the study period, serum samples for HCV RNA were obtained at Baseline (Day 1), and at every protocol-stipulated post-Baseline study visit (Days 2,4, 8,11, 15,16, 17,22, and 29). Serum samples for HCV RNA were also collected during protocol-stipulated follow-up visits for patients prematurely discontinued from the study.
The antiviral activity associated with the first two cohorts (50 and 100 mg per day) in the ongoing study is summarized in the following tables and graphs. Although the duration of dosing was short (15 days) and the initial dose levels low, there were already apparent effects on the levels of HCV RNA in the plasma of infected patients.
Table 37: Summary Statistics of HCV RNA in Log Scale Day -1 1 2 4 8 11 15 16 17 22 29 Treatment Placebo N 6 5 5 4 4 4 4 4 3 4 3 Median 6.45 6.25 6.25 6.52 6.42 6.28 6.58 6. 51 6.64 6.35 6.61 Mean 6.45 6.28 6.40 6.48 6.36 6.34 6.54 6.52 6.50 6.40 6.40 StdErr 0.25 0.12 0.15 0.18 0.24 0. 16 0. 11 0. 19 0. 31 0.23 0.30 50 mg N 10 10 10 10 10 10 10 10 10 10 10 Median 6. 81 6.69 6.58 6.55 6.56 6.46 6.57 6.45 6.54 6.73 6.67 Mean 6.72 6.72 6.60 6.56 6.62 6.47 6.57 6.57 6.54 6.64 6. 71 StdErr 0. 11 0. 11 0.12 0.06 0.10 0.09 0.08 0. 11 0.08 0.10 0.09 100 mg N I 1 10 10 10 9 10 10 9 9 10 4 Median 6.75 6.93 6.80 6.46 6.59 6.56 6. 41 6.40 6.72 6.66 6. 71 Mean 6.60 6.68 6.52 6.43 6.42 6.36 6.30 6.23 6.65 6.53 6.67 StdErr 0.16 0.24 0.23 0.21 0.24 0.22 0.22 0.23 0.16 0.18 0. 17
Table 38: Summary Statistics of Change From Baseline (Day 1) in Logo HCV RNA Day 2 4 8 11 15 16 17 22 29 Treatment Placebo N 5 4 4 4 4 4 3 4 3 Median 0. 17 0.21 0.15 0.08 0.31 0.21 0.27 0.17 0.09 Mean 0. 12 0.22 0. 10 0.08 0.28 0.25 0.15 0.14 0.09 StdErr 0.09 0. 12 0.16 0.06 0. 15 0. 10 0.18 0.09 0.16 50 mg N 10 10 10 10 10 10 10 10 10 Median-0. 07-0. 13-0. 06-0.26-0. 10-0. 13-0. 21-0.09-0. 04 Mean -0.13 -0.16 0.11 -0. 26-0. 15-0. 15-0. 18-0. 09-0.01 StdErr 0.05 0.07 0. 05 0. 06 0. 08 0.05 0.07 0.06 0.10 100 mg N 10 10 9 10 10 9 9 10 4 Median-0. 12-0. 24-0.20-0. 28-0.43-0. 49-0. 24-0. 19-0. 12 Mean-0.16-0. 25-0.21-0. 32-0.38-0. 39-0. 18-0. 15 0. 13 StdErr 0.07 0.10 0. 16 0. 13 0. 12 0.14 0.15 0. 13 0.28
The clinical evaluation of val-mCyd in the tested patients is shown in Figure 21. This figure depicts the median change from baseline in Log, o HCV RNA by visit.
EXAMPLE 41: EVALUATION OF TEST COMPOUNDS Several of the compounds described herein were tested in the BVDV cell protection assay described above. Figure 22 is a table of the EC50 and CC50 of representative compounds in a BVDV cell protection assay, to show the efficacy of the compounds.
This invention has been described with reference to its preferred embodiments.
Variations and modifications of the invention, will be obvious to those skilled in the art from the foregoing detailed description of the invention. It is intended that all of these variations and modifications be included within the scope of this invention. 'le 1 R R X X Y acyl H H H H acyl H H H NH2 acyl H H H NH-cyclopropyl acyl H H H NH-methv1 acyl H H H NH-ethyl acyl H H H NH-acetyl acyl H H H OH t H H H OMe acyl H H H OEt acyl H H 0-cyclopropyl acyl H H H O-acetyl acyl H H H SH acyl H _ H H SMe acyl H _ H H SEt acyl H H H S-cyclopropyl acyl H H H F acyl H H H C1 acyl H H H Br acyl H H H I acyl acyl H H H acyl acyl H H NH2 acyl acyl H H NH-cyclopropyl acyl acyl H H NH-methyl acyl acyl H H NH-ethyl acyiscyiH H NH-acetyl acyl acyl H H OH acyl acyl H H OMe acyl acyl H H OEt acyl acyl H H O-cyclopropyl acyl acyl H H 0-acetyl acyl acyl H H SH acyl acyl H H SMe acyl acyl _ H H SEt acyl acyl H H S-c lopropyl acyl acyl H H F acyl acyl H H C1 acyl acyl H H Br acyl acyl H H I acyl amino acid H H H acyl amino acid H H NH2 acyl amino acid H H NH-cyclopropyl acyl amino acid H H NH-methyl acyl amino acid H H NH-ethyl acyl amino acid H H NH-acetyl acyl amino acid H H OH R R X X Y acyl amino acid H H OMe acyl amino acid H H OEt acyl amino acid H H 0-cyclopropyl acyl amino acid H H 0-acetyl acyl amino acid H H SH acyl amino acid H H SMe acyl amino acid H H SEt acyl amino acid H H S-cyclopropyl acyl amino acid H H F acyl amino acid H H CI acyl amino acid H H Br acyl amino acid H H I H acyl H H H H acyl H H NH2 H acyl H H NH-cyclopropyl H acyl H H NH-methyl H acyl H H NH-ethyl H acyl H H NH-acetyl H acyl H H OH H acyl H H OMe H acyl H H OEt H acyl H H 0-cyclopropyl H acyl H H O-acetyl H acyl H H SH H acyl H H SMe H acyl H H SEt H acyl H H S-cyclopropyl H acyl H H F H acyl H H C1 H acyl H H Br H acyl H H H amino acid H H H H amino acid H H NH2 H amino acid H H NH-cyclopropyl H amino acid H H NH-methyl H amino acid H H NH-ethyl H amino acid H H NH-acetyl H amino acid H H OH H amino acid H H OMe H amino acid H H OEt H amino acid H 0-cyclopropyl H amino acid H 0-acetyl H amino acid H H SH H amino acid H H SMe H amino acid H H SEt H amino acid H H S-c clo ro 1 H amino acid H H F R R3 Xl x2 H amino acid H H Cl H amino acid H H Br H amino acid H H I amino acid amino acid H H H amino acid amino acid H H NH2 amino acid amino acid H H NH-c clo ro 1 amino acid amino acid H H NH-methyl amino acid amino acid H H NH-ethyl amino acid amino acid H H NH-acetyl amino acid amino acid H H OH amino acid amino acid H H OMe amino acid amino acid H H OEt amino acid amino acid H 0-cyclopropyl amino acid amino acid H H 0-acetyl amino acid amino acid H H SH amino acid amino acid H H SMe amino acid amino acid H H SEt amino acid amino acid H H S-cyclopropyl amino acid amino acid H H F amino acid amino acid H H Cl amino acid amino acid H H Br amino acid amino acid H H I amino acid H H H H amino acid H H H NH2 amino acid H H H NH-cyclopropyl amino acid H H H NH-methyl amino acid H H H NH-ethyl amino acid H H H NH-acetyl amino acid H H H OH amino acid H H H OMe amino acid H H H OEt amino acid H H H O-cyclopropyl amino acid H H H 0-acetyl amino acid H H H SH amino acid H H H SMe amino acid H H H SEt amino acid H H H S-cyclopropyl amino acid H H H F amino acid H H H ci amino acid H H H Br amino acid H H H I amino acid acyl H H H amino acid acyl H H NH2 amino acid acyl H H NH-cyclopropyl amino acid acyl H H NH-methyl amino acid acyl H H NH-ethyl amino acid acyl H H NH-acetyl Ruz y amino acid acyl H-H OH amino acid acyl H H OMe amino acid acyl H H OEt amino acid 0-cyclopropyl amino acid acyl H H 0-acetyl amino acid acyl H H SH amino acid acyl H H SMe amino acid acyl H H SEt amino acid acyl H H S-cyclopropyl amino acid acyl H H F amino acid acyl H H C1 amino acid acyl H H Br amino acid acyl H H I acyl H F H H acyl H F H NH2 acyl H F H NH-cyclopropyl acyl H F H NH-methyl acyl H F H NH-ethyl acyl H F H NH-acetyl acyl H F H OH acyl H F H OMe acyl H F H OEt acyl H F H 0-cyclopropyl acyl H F H O-acetyl acyl H F H SH acyl H F H SMe acyl H F H SEt acyl H F H S-cyclopropyl acyl H F H F acyl H F H C1 acyl H F H Br acyl H F H I acyl acyl F H H acyl acyl F H NH2 acyl acyl F H NH-cycloproW acyl acyl F H NH-methyl acyl acyl F H NH-ethyl acyl acyl F H NH-acetyl acyl acyl F H OH acyl acyl F H OMe acyl acyl F H OEt acyl acyl F H O-cyclopropyl acyl acyl F H 0-acetyl acyl acyl F H SH acyl acyl F H SMe acyl acyl F H SEt acyl acyl F H S-cyclopropyl R'R'X'X'Y acyl acyl F acyl acyl F H C1 acyl acyl F H Br acyl acyl F H I acyl amino acid F H H acyl amino acid F H NH2 acyl amino acid F H NH-cyclopropyl acyl amino acid F H NH-methyl acyl amino acid F H NH-ethyl acyl amino acid F H NH-acetyl acyl amino acid F H OH acyl amino acid F H OMe acyl amino acid F H OEt acyl amino acid F H O-cyclopropyl acyl amino acid F H 0-acetyl acyl amino acid F H SH acyl amino acid F H SMe acyl amino acid F H SEt acyl amino acid F H S-cyclopropyl acyl amino acid F H F acyl amino acid F H C1 acyl amino acid F H Br acyl amino acid F H I H acyl F H H H acyl F H NH2 H acyl F H NH-cyclopropyl H acyl F H NH-methyl H acyl F H NH-ethyl H acyl F H NH-acetyl H _ acyl F H OH H acyl F H OMe H acyl F H OEt H acyl F H O-cyclopropyl H acyl F H 0-acetyl H acy1 F H SH H acyl F H SMe H acyl F H SEt H acyl F H S-cyclopropyl H acyl F H F H acyl F H C1 H acyl F H Br H acyl F H H amino acid F H H H amino acid F H NH2 H amino acid F H NH-cyclopropyl H arnino acid F H NH-methyl H amino acid F H NH-ethyl R R X X Y H amino acid F H NH-acetyl H amino acid F H OH H amino acid F H OMe H amino acid F H OEt H amino acid F H O-c clo ro 1 H amino acid F H 0-acetyl H amino acid F H SH H amino acid F H SMe H amino acid F H SEt H amino acid F H S-cyclopropyl H amino acid F H F H amino acid F H Cl H amino acid F H Br H amino acid F H I amino acid amino acid F H H amino acid amino acid F H NH2 amino acid amino acid F H amino acid amino acid F H NH-methyl amino acid amino acid F H NH-ethyl amino acid amino acid F H NH-acetyl amino acid amino acid F H OH amino acid amino acid F H OMe amino acid amino acid F H OEt amino acid amino acid F H 0-cyclopropyl amino acid amino acid F H 0-acetyl amino acid amino acid F H SH amino acid amino acid F H SMe amino acid amino acid F H SEt amino acid amino acid F H S-cyclopropyl amino acid amino acid F H F amino acid amino acid F H Cl amino acid amino acid F H Br amino acid amino acid F H I amino acid H F H H amino acid H F H NH2 amino acid H F H NH-cyclopropyl amino acid H F H NH-methyl amino acid H F H NH-ethyl amino acid H F H NH-acetyl amino acid H F H OH amino acid H F H OMe amino acid H F H OEt amino acid 0-cyclopropyl amino acid H F H O-acetyl amino acid H F H SH amino acid H F H SMe amino acid H F H SEt R R X X Y amino acid H F H S-cyclopropyl amino acid H F H F amino acid H F H Cl amino acid H F H Br amino acid H F H I amino acid acyl F H H amino acid acyl F H NH2 amino acid ac 1 F H NH-c clo ro 1 amino acid acyl F H NH-methyl amino acid acyl F H NH-ethyl amino acid acyl F H NH-acetyl amino acid acyl F H OH amino acid acyl F H OMe amino acid acyl F H OEt amino acid 0-cyclopropyl amino acid acyl F H O-acetyl amino acid acyl F H SH amino acid acyl F H SMe amino acid acyl F H SEt amino acid acyl F H S-cyclopropyl amino acid acyl F H F amino acid acyl F H Cl amino acid acyl F H Br amino acid acyl F H I acyl H H F H acyl H H F NH2 acyl H H F NH-cyclopropyl acyl H H F NH-methyl acyl H H F NH-ethyl acyl H H F NH-acetyl acyl H H F OH acyl H H F OMe acyl H H F OEt acyl H H F 0-cyclopropyl acyl H H F 0-acetyl acyl H H F SH acyl H H F SMe acyl H H F SEt ac 1 H H F S-c clo ro 1 w acyl H H F F acyl H H F C1 acyl H H F Br acyl H H F I acyl acyl H F H acyl acyl H F NH2 ac 1 ac 1 H F NH-c clo ro 1 acyl acyl H F NH-methyl R R3 Xl x2 y acyl acyl H F NH-ethyl acyl acyl H F NH-acetyl acyl acyl H F OH acyl acyl H F OMe X acyl acyl H F OEt acyl acyl H F O-cyclopropyl acyl acyl H F 0-acetyl acyl acyl H F SH acyl acyl H F SMe acyl acyl H F SEt acyl acyl H F S-cyclopropyl acyl acyl H F F acyl acyl H F C1 acyl acyl H F Br acyl acyl H F I acyl amino acid H F H acyl amino acid H F NH2 acyl amino acid H F NH-cyclopropyl acyl amino acid H F NH-methyl acyl amino acid H F NH-ethyl acyl amino acid H F NH-acetyl acyl amino acid H F OH acyl amino acid H F OMe acyl amino acid H F OEt acyl amino acid H F O-cyclopropyl acyl amino acid H F 0-acetyl acyl amino acid H F SH acyl amino acid H F SMe acyl amino acid H F SEt acyl amino acid H F S-c acyl amino acid H F F acyl amino acid H F Cl acyl amino acid H F Br acyl amino acid H F I H acyl H F H H acyl H F NH2 H acyl H F NH-cyclopropyl H acyl H F NH-methyl H acyi H F NH-ethyl H acyl H F NH-acetyl H acyl H F OH H acyl H F OMe H acyl H F OEt H acyl H F 0-cyclopropyl H acyl H F 0-acetyl H acyl H F SH H acyl H F SMe R2 R3-~ Xl x2 H acyl H F SEt H acyl H F S-cyclopropyl H acyl H F F H acyl H F C1 H acyl H F Br H acyl H F I H amino acid H F H H amino acid H F NH2 H amino acid H F NH-cyclopropyl H amino acid H F NH-methyl H amino acid H F NH-ethyl H amino acid H F NH-acetyl H amino acid H F OH H amino acid H F OMe H amino acid H F OEt H amino acid H F O-cyclopropyl H amino acid F0-acetyl H amino acid H F SH H amino acid H F SMe H amino acid H F SEt H amino acid H F S-cyclopropyl H amino acid H F F H amino acid H F C1 H amino acid H F Br H amino acid. H F I amino acid amino acid H F H amino acid amino acid H F NH2 amino acid amino acid H F NH-cyclopropyl amino acid amino acid H F NH-methyl amino acid amino acid H F NH-ethyl amino acid amino acid H F NH-acetyl amino acid amino acid H F OH amino acid amino acid H F OMe amino acid amino acid H F OEt amino acid amino acid H F 0-cyclopropyl amino acid amino acid H F O-acetyl amino acid amino acid H F SH amino acid amino acid H F SMe amino acid amino acid H F SEt amino acid amino acid H F S-cyclopropyl amino acid amino acid H F F amino acid amino acid H F Cl amino acid amino acid H F Br amino acid amino acid H F I amino acid H H F H amino acid H H F NH2 amino acid H H F NH-cyclopropyl R R'X X Y amino HR3 H F | NH-methyl amino acid H H F NH-ethyl amino acid H H F NH-acetyl amino acid H H F OH amino acid H H F OMe amino acid H H F OEt amino acid F0-cyclopropyl amino acid H H F O-acetyl amino acid H H F SH amino acid H H F SMe amino acid H H F SEt amino acid H H F S-cyclopropyl amino acid H H F F amino acid H H F Cl amino acid H H F Br amino acid H H F I amino acid acyl H F H amino acid acyl H F NH2 amino acid acyl H F NH-cyclopropyl amino acid acyl H F NH-methyl amino acid acyl H F NH-ethyl amino acid acyl H F NH-acetyl amino acid acyl H F OH amino acid acyl H F OMe amino acid acyl H F OEt amino acid ac 1 H F O-c clo ro 1 amino acid acyl H F 0-acetyl amino acid acyl H F SH amino acid acyl H SMe amino acid acyl H F SEt amino acid acyl H F S-cyclopropyl amino acid acyl H F F amino acid acyl H F C1 amino acid acyl H F Br amino acid acyl H F I acyl H NH2 H H acyl H NH2 H NH2 acyl H NH2 H NH-cyclopropyl acyl H NH2 H NH-methyl acyl H NH2 H NH-ethyl acyl H NH2 H NH-acetyl acyl H NH2 H OH acyl H NH2 H OMe acyl H NH2 H OEt acyl H 2 H 0-cyclopropyl acyl H NH2 H O-acetyl acyl H NH2 H SH R R X X Y acyl H NH2 H SMe acyl H NH2 H SEt acyl H NH2 H S-cyclopropyl acyl H NH2 H F acyl H NH2 H Ci acyl H NH2 H Br acyl H NH2 H I acyl acyl NH2 H H acyl acyl NH2 H NH2 acyl acyl NH2 H NH-cyclopropyl acyl acyl NH2 H NH-methyl acyl acyl NH2 H NH-ethyl acyl acyl NH2 H NH-acetyl acyl acyl NH2 H OH acyl acyl NH2 H OMe acyl acyl NH2 H OEt acyl acyl NH2 H O-cyclopropyl acyl acyl NH2 H 0-acetyl acyl acyl NH2 H SH acyl acyl NH2 H SMe acyl acyl NH2 H SEt acyl acyl NH2 H S-cyclopropyl acyl acyl NH2 H F acyl acyl NH2 H C1 acyl acyl NH2 H Br acyl acyl NH2 H I acyl amino acid NH2 H H acyl amino acid NH2 H NH2 acyl amino acid NH2 H NH-cyclopropyl acyl amino acid NH2 H NH-methyl acyl amino acid NH2 H NH-ethyl acyl amino acid NH2 H NH-acetyl acyl amino acid NH2 H OH acyl amino acid NH2 H OMe acyl amino acid NH2 H OEt acyl amino acid NH2 H 0-cyclopropyl acyl amino acid NH2 H 0-acetyl acyl amino acid NH2 H SH acyl amino acid NH2 H SMe acyl amino acid NH2 H SEt acyl amino acid NH2 H S-cyclopropyl acyl amino acid NH2 H F acyl amino acid NH2 H Cl acyl amino acid NH2 H Br acyl amino acid NH2 H I H acyl NH2 H H H acyl NH2 H NH2 R R X X Y H acyl NH2 H NH-cyclopropyl H acyl NH2 H NH-methyl H acyl NH2 H NH-ethyl H acyl NH2 H NH-acetyl H acyl NH2 H OH H acyl NH2 H OMe H acyl NH2 H OEt H H0-cyclopropyl H acyl NH2 H O-acetyl H acyl NH2 H SH H acy1 NH2 H SMe H acyl NH2 H SEt H acyl NH2 H S-cyclopropyl H acyl NH2 H F H acyl NH2 H C1 H acyl NH2 H Br H acyl NH2 H I H amino acid NH2 H H H amino acid NH2 H NH2 H amino acid NH2 H NH-cyclopropyl H amino acid NH2 H NH-methyl H amino acid NH2 H NH-ethyl S H amino acid NH2 H NH-acetyl H amino acid NH2 H OH H amino acid NH2 H OMe H amino acid NH2 H OEt H amino acid NH2 H 0-cyclopropyl H amino acid NH2 H O-acetyl H amino acid NH2 H SH H amino acid NH2 H SMe H amino acid NH2 H SEt H amino acid NH2 H S-cyclopropyl H amino acid NH2 H F H amino acid NHz H C1 H amino acid NH2 H Br H amino acid NH2 H I amino acid amino acid NH2 H H amino acid amino acid NH2 H NH2 amino acid amino acid NH2 H NH-cyclopropyl amino acid amino acid NH2 H NH-methyl amino acid amino acid NH2 H NH-ethyl amino acid amino acid NH2 H NH-acetyl amino acid amino acid NH2 H OH amino acid amino acid NH2 H OMe amino acid amino acid NH2 H OEt amino acid amino acid NH2 H 0-cyclopropyl amino acid amino acid NH2 H O-acetyl R R X X Y amino acid amino acid NH2 H SH amino acid amino acid NH2 H SMe amino acid amino acid NH2 H SEt amino acid amino acid NH2 H S-cyclopropyl amino acid amino acid NH2 H F amino acid amino acid NH2 H ci amino acid amino acid NH2 H Br amino acid amino acid NH2 H I amino acid H NH2 H H amino acid H NH2 H NH2 amino acid H NH2 H NH-cyclopropyl amino acid H NH2 H NH-methyl amino acid H NH2 H NH-ethyl amino acid H NH2 H NH-acetyl amino acid H NH2 H OH amino acid H NH2 H OMe amino acid H NH2 H OEt amino acid H NH2 H 0-cyclopropyl amino acid H NH2 H 0-acetyl amino acid H NH2 H SH amino acid H NH2 H SMe amino acid H NH2 H SEt amino acid H NH2 H S-cyclopropyl amino acid H NH2 H F amino acid H NH2 H C1 amino acid H NH2 H Br amino acid H NH2 H I amino acid acyl NH2 H amino acid acyl NH2 H NH2 amino acid acyl NH2 H NH-cyclopropyl amino acid acyl NH2 H NH-methyl amino acid acyl NH2 H NH-ethyl amino acid acyl NH2 H NH-acetyl amino acid acyl NH2 H OH amino acid acyl NH2 H OMe amino acid acyl NH2 H OEt amino acid acyl NH2 H O-cyclopropyl amino acid acyl NH2 H 0-acetyl amino acid acyl NH2 H SH amino acid acyl NH2 H SMe amino acid acyl NH2 H SEt amino acid acyl NH2 H S-cyclopropyl amino acid acyl NH2 H F amino acid acyl NH2 H C1 amino acid acyl NH2 H Br amino acid acyl NH2 H acyl H R R X'X Y acyl H H NH2 NH2 acyl H H NH2 NH-cyclopropyl acyl H H NH2 NH-methyl acyl H H NH2 NH-ethyl acyl H H NH2 NH-acetyl acyl H H NH2 OH acyl H H NH2 OMe acyl H H NH2 OEt acyl H H NH2 0-cyclopropyl acyl H H NH2 O-acetyl acyl H H NH2 SH acyl H H NH2 SMe acyl H H NH2 SEt acyl H H NH2 S-cyclopropyl acyl H H NH2 F acyl H H NH2 C1 acyl H H NH2 Br acyl H H NH2 I acyl acyl H NH2 H acyl acyl H NH2 NH2 acyl acyl H NH2 NH-cyclopropyl acyl acyl H NH2 NH-methyl acyl acyl H NH2 NH-ethyl acyl acyl H NH2 NH-acetyl acyl acyl H NH2 OH acyl acyl H NH2 OMe acyl acyl H NH2 OEt acyl acyl H NH2 O-cyclopropyl acyl acyl H NH2 0-acetyl acyl acyl H NH2 SH acyl acyl H NH2 SMe acyl acyl H NH2 SEt acyl acyl H NH2 S-cyclopropyl acyl acyl H NH2 F acyl acyl H NH2 C1 acyl acyl H NH2 Br acyl acyl H NH2 I acyl amino acid H NH2 H acyl amino acid H NH2 NH2 acyl amino acid H NHz NH-cyclopropyl acyl amino acid H NH2 NH-methyl acyl amino acid H NH2 NH-ethyl acyl amino acid H NH2 NH-acetyl acyl amino acid H NH2 OH acyl amino acid H NH2 OMe acyl amino acid H NH2 OEt acyl amino acid H NH2 O-cyclopropyl R R X X Y acyl amino acid H NH2 O-acetyl acyl amino acid H NH2 SH acyl amino acid H NH2 SMe acyl amino acid H NH2 SEt acyl amino acid H NH2 S-cyclopropyl acyl amino acid H NH2 F acyl amino acid H NH2 C1 acyl amino acid H NH2 Br acyl amino acid H NH2 I H acyl H NH2 H H acyl H NH2 NH2 H ac 1 H NHz NH-cyclo ro 1 H acyl H NH2 NH-methyl H acyl H NH2 NH-ethyl H acyl H NH2 NH-acetyl H acyl H NH2 OH H ac H NH2 OMe H acyl H NH2 OEt H acyl H NH2 O-cyclopropyl H acyl H NH2 O-acetyl H acyl H NH2 SH H acyl H NH2 SMe H acyl H NH2 SEt H acyl H NH2 S-cyclopropyl H acyl H NH2 F H acyl H NH2 Ci H acyl H NH2 Br H acyl H NH2 I H amino acid H NH2 H H amino acid H NH2 NH2 H amino acid H NH2 NH-cyclopropyl H amino acid H NH2 NH-methyl H amino acid H NH2 NH-ethyl # H amino acid H NH2 NH-acetyl H amino acid H NH2 OH H amino acid H NH2 OMe H amino acid H NH2 OEt H amino acid H NH2 0-cyclopropyl H amino acid H NH2 0-acetyl H amino acid H NH2 SH H amino acid H NH2 SMe H amino acid H NH2 SEt H amino acid H NH2 S-cyclopropyl H amino acid H NH2 F H amino acid H NH2 Cl H amino acid H NH2 Br H amino acid H NH2 R ~~ R3 Xl X2-Y amino acid amino acid H NH2 H amino acid amino acid H NH2 NH2 amino acid amino acid H NH2 NH-cyclopropyl amino acid amino acid H NH2 NH-methyl amino acid amino acid H NH2 NH-ethyl amino acid amino acid H NH2 NH-acetyl amino acid amino acid H NH2 OH amino acid amino acid H NH2 OMe amino acid amino acid H NH2 OEt amino acid arnino acid H NH2 O-cyclopropyl amino acid amino acid H NH2 O-acetyl amino acid amino acid H NHz SH amino acid amino acid H NH2 SMe amino acid amino acid H NH2 SEt amino acid amino acid H NH2 S-cyclopropyl amino acid amino acid H NH2 F amino acid amino acid H NH2 C1 amino acid amino acid H NH2 Br amino acid amino acid H NH2 I amino acid H H NH2 amino acid H H NH2 NH2 amino acid H H NH2 NH-cyclopropyl amino acid H H NH2 NH-methyl amino acid H H NH2 NH-ethyl amino acid H H NH2 NH-acetyl amino acid H H NH2 OH amino acid H H NH2 OMe amino acid H H NH2 OEt amino acid H H NH2 O-cyclopropyl amino acid H H NH2 0-acetyl amino acid H H NH2 SH amino acid H H NH2 SMe amino acid H H NH2 SEt amino acidHH NHz S-cyclopropyi amino acid H H NH2 F amino acid H H NH2 C1 amino acid H H NH2 Br amino acid H H NH2 I amino acid acyl H NH2 H amino acid acyl H NH2 NH2 amino acid acyl H NH2 NH-cyclopropyl amino acid acyl H NH2 NH-methyl amino acid acyl H NH2 NH-ethyl amino acid acyl H NH2 NH-acetyl amino acid acyl H NH2 OH amino acid acyl H NH2 OMe amino acid acyl H NH2 OEt R2 R3 Xl x2 amino acid acyl H NH2 O-cyclopropyl amino acid ac 1 H NH2 O-acetyl amino acid acyl H NH2 SH amino acid acyl H NH2 SMe amino acid acyl H NH2 SEt amino acid acyl H NH2 S-cyclopropyl amino acid acyl H NH2 F amino acid acyl H NH2 Cl amino acid acyl H NH2 Br amino acid acyl H NH2 I acyl H NH2 NH2 H acyl H NH2 NH2 NH2 acyl H NH2 NH2 NH-cyclopropyl acyl H NH2 NH2 NH-methyl acyl H NH2 NH2 NH-ethyl acyl H NH2 NH2 NH-acetyl acyl H NH2 NH2 OH acyl H NH2 NH2 OMe acyl H NH2 NH2 OEt acyl H NH2 NH2 O-cyclopropyl acyl H NH2 NH2 0-acetyl acyl H NH2 NH2 SH acyl H NH2 NH2 SMe acyl H NH2 NH2 SEt acyl H NH2 NH2 S-cyclopropyl acyl H NH2 NH2 F acyl H NH2 NH2 Cl acyl H NH2 NH2 Br acyl H NH2 NH2 I acyl acyl NH2 NH2 H acyl acyl NH2 NH2 NH2 acyl acyl NH2 NH2 NH-cyclopropyl acyl acyl NH2 NH2 NH-methyl acyl acyl NH2 NH2 NH-ethyl acyl acyl NH2 NH2 NH-acetyl acyl acyl NH2 NH2 OH acyl acyl NH2 NH2 OMe acyl acyl NH2 NH2 OEt acyl acyl NH2 NH2 O-cyclopropyl acyl acyl NH2 NH2 O-acetyl acyl acyl NH2 NH2 SH acyl acyl NH2 NH2 SMe acyl acyl NH2 NH2 SEt acyl acyl NH2 NH2 S-cyclopropyl acyl acyl NH2 NH2 F ac 1 ac 1 NHz NHz Cl acyl acyl NH2 NH2 Br R R X X Y acyl acyl NH2 NH2 I acyl amino acid NH2 NH2 H acyl amino acid NH2 aNH2 0 NH2 acyl amino acid NH2 NH2 NH-cyclopropyl acyl amino acid NH2 NH2 NH-methyl acyl amino acid NH2 NH2 NH-ethyl acyl amino acid NH2 NH2 NH-acetyl acyl amino acid NH2 NH2 OH acyl amino acid NH2 NH2 OMe acyl amino acid NH2 NH2 OEt acyl amino acid NH2 NH2 O-cyclopropyl acyl amino acid NH2 NH2 0-acetyl acyl amino acid NH2 NH2 SH acyl amino acid NH2 NH2 SMe acyl amino acid NH2 NH2 SEt acyl amino acid NH2 NH2 S-cyclopropyl acyl amino acid NH2 NH2 F acyl amino acid NH2 NH2 C1 acyl amino acid NH2 NH2 Br acyl amino acid NH2 NH2 I H acyl NH2 NH2 H H acyl NH2 NH2 NH2 H ac 1 NHz NHz NH-c clo ro 1 H acyl NH2 NH2 NH-methyl H acyl NH2 NH2 NH-ethyl H acyl NH2 NH2 NH-acetyl H acyl NH2 NH2 OH H acyl NH2 NH2 OMe H acyl NH2 NH2 OEt H acyl NH2 NH2 0-cyclopropyl H acyl NH2 NH2 O-acetyl H acyl NH2 NH2 SH H acyl NH2 NH2 SMe H acyl NH2 NH2 SEt H acyl NHz NHz S-cyclo ro 1 H acyl NH2 NH2 F H acyl NH2 NH2 Cl H acyl NH2 NH2 Br H acyl NH2 NH2 I H amino acid NH2 NHz H H amino acid NH2 NH2 NHz H amino acid NH2 NH2 NH-cyclopropyl H amino acid NH2 NH2 NH-methyl H amino acid NH2 NH2 NH-ethyl H amino acid NH2 NH2 NH-acetyl H amino acid NH2 NH2 OH H amino acid NH2 NH2 OMe R2 R3 X1 X2 H amino acid NH2 NH2 OEt H amino acid NH2 NH2 O-cyclopropyl H amino acid NH2 NH2 0-acetyl H amino acid NH2 NH2 SH H amino acid NH2 NH2 SMe H amino acid NH2 NH2 SEt H amino acid NH2 NH2 S-cyclopropyl H amino acid NH2 NH2 F H amino acid NH2 NH2 C1 H amino acid NH2 NH2 Br H amino acid NH2 NH2 I amino acid amino acid NH2 NH2 H amino acid amino acid NH2 NH2 NH2 amino acid amino acid NH2 NH2 NH-cyclopropyl amino acid amino acid NH2 NH2 NH-methyl amino acid amino acid NH2 NH2 NH-ethyl amino acid amino acid NH2 NH2 NH-acetyl amino acid amino acid NH2 NH2 OH amino acid amino acid NH2 NH2 OMe amino acid amino acid NH2 NH2 OEt amino acid amino acid NH2 NH2 0-cyclopropyl amino acid amino acid NH2 NH2 0-acetyl amino acid amino acid NH2 NH2 SH amino acid amino acid NH2 NH2 SMe amino acid amino acid NH2 NH2 SEt amino acid amino acid NH2 NH2 S-cyclopropyl amino acid amino acid NH2 NH2 F amino acid amino acid NH2 NH2 C1 amino acid amino acid NH2 NH2 Br amino acid amino acid NH2 NH2 I amino acid H NH2 NH2 H amino acid H NH2 NH2 NH2 amino acid H NH2 NH2 NH-cyclopropyl amino acid H NH2 NH2 NH-methyl amino acid H NH2 NH2 NH-ethyl amino acid H NH2 NH2 NH-acetyl amino acid H NH2 NH2 OH amino acid H NH2 NH2 OMe amino acid H NH2 NH2 OEt amino acid H NH2 NH2 0-c clopropyl amino acid H NH2 NH2 0-acetyl amino acid H NH2 NH2 SH amino acid H NH2 NH2 SMe amino acid H NH2 NH2 SEt amino acid H NH2 NH2 S-cyclopropyl amino acid H NH2 NH2 F amino acid H NH2 NH2 C1 R R w Xi Y amino acid H NH2 NH2 Br amino acid H NH2 NH2 I amino acid acyl NH2 NH2 H amino acid acyl NH2 NH2 NH2 amino acid acyl NH2 NH2 NH-cyclopropyl amino acid acyl NH2 NH2 NH-methyl amino acid acy1 NH2 NH2 NH-ethyl amino acid acyl NH2 NH2 NH-acetyl amino acid acyl NH2 NH2 OH amino acid acyl NH2 NH2 OMe amino acid acyl NH2 NH2 OEt amino acid ac 1 NHz NHz O-c clo ro 1 amino acid acyl NH2 NH2 0-acetyl amino acid acyl NH2 NH2 SH amino acid acyl NH2 NH2 SMe amino acid acyl NH2 NH2 SEt amino acid acyl NH2 NH2 S-cyclopropyl amino acid acyl NH2 NH2 F amino acid acyl NH2 NH2 C1 amino acid acyl NH2 NH2 Br amino acid acyl NH2 NH2 I acyl H OH NH2 H acyl H OH NH2 NH2 acyl H OH NH2 NH-cyclopropyl acyl H OH NH2 NH-methyl acyl H OH NH2 NH-ethyl acyl H OH NH2 NH-acetyl acyl H OH NH2 OH acyl H OH NH2 OMe acyl H OH NH2 OEt acyl H OH NH2 O-cyclopropyl acyl H OH NH2 0-acetyl acyl H OH NH2 SH acyl H OH NH2 SMe acyl H OH NH2 SEt acyl H OH NH2 S-cyclopropyl acyl H OH NH2 F acyl H OH NH2 C1 acyl H OH NH2 Br acyl H OH NH2 I acyl acyl OH NH2 H acyl acyl OH NH2 NH2 acyl acyl OH NH2 NH-cyclopropyl acyl acyl OH NH2 NH-methyl acyl acyl OH NH2 NH-ethyl acyl acyl OH NH2 NH-acetyl acyl acyl OH NH2 OH R2 w acyl acyl OH NH2 OMe acyl acyl OH NH2 OEt acyl acyl OH NH2 O-cyclopropyl acyl acyl OH NH2 O-acetyl acyl acyl OH NH2 SH acyl acyl OH NH2 SMe acyl acyl OH NH2 SEt acyl acyl OH NH2 S-cyclopropyl acyl acyl OH NH2 F ac 1 ac 1 OH NHz Cl acyl acyl OH NH2 Br acyl acyl OH NH2 I acyl amino acid OH NHz H acyl amino acid OH NH2 NH2 acyl amino acid OH NH2 NH-cyclopropyl acyl amino acid OH NH2 NH-methyl acyl amino acid OH NH2 NH-ethyl acyl amino acid OH NH2 NH-acetyl acyl amino acid OH NH2 OH acyl amino acid OH NH2 OMe acyl amino acid OH NH2 OEt acyl amino acid OH NH2 O-cyclopropyl acyl amino acid OH NH2 0-acetyl acyl amino acid OH NH2 SH acyl amino acid OH NH2 SMe acyl amino acid OH NH2 SEt acyl amino acid OH NH2 S-cyclopropyl acyl amino acid OH NH2 F acyl amino acid OH NH2 C1 acyl amino acid OH NH2 Br acyl amino acid OH NH2 I H acyl OH NH2 H H acyl OH NH2 NH2 H acyl OH NH2 NH-cyclopropyl H acyl OH NH2 NH-methyl H acy1 OH NH2 NH-ethyl w H acyl OH NH2 NH-acetyl H acyl OH NH2 OH H acyl OH NH2 OMe H acyl OH NH2 OEt H acyl OH NH2 0-cyclopropyl H acyl OH NH2 0-acetyl H acyl OH NH2 SH H acyl OH NH2 SMe H acyl OH NH2 SEt H acyl OH NH2 S-cyclopropyl H acyl OH NH2 F R2 R3 Xl x2 H acyl OH NH2 C1 H acyl OH NH2 Br H acyl OH NH2 I H amino acid OH NH2 H H amino acid OH NH2 NH2 H amino acid OH NH2 NH-cyclopropyl H amino acid OH NH2 NH-methyl H amino acid OH NH2 NH-ethyl H amino acid OH NH2 NH-acetyl H amino acid OH NH2 OH H amino acid OH NH2 OMe H amino acid OH NH2 OEt H amino acid OH NH2 0-cyclopropyl H amino acid OH NH2 O-acetyl H amino acid OH NH2 SH H amino acid OH NH2 SMe H amino acid OH NH2 SEt amino acid OH NH2 S-cyclopropyl H amino acid OH NH2 F H amino acid OH NHZ Cl H amino acid OH NH2 Br H amino acid OH NH2 I amino acid amino acid OH NH2 H amino acid amino acid OH NH2 NH2 amino acid amino acid OH NH2 NH-cyclopropyl amino acid amino acid OH NH2 NH-methyl amino acid amino acid OH NH2 NH-ethyl amino acid amino acid OH NH2 NH-acety1 amino acid amino acid OH NH2 OH amino acid amino acid OH NH2 OMe amino acid amino acid OH NH2 OEt amino acid amino acid OH NH2 O-cyclopropyl amino acid amino acid OH NH2 0-acetyl amino acid amino acid OH NH2 SH amino acid amino acid OH NH2 SMe amino acid amino acid OH NH2 SEt amino acid amino acid OH NH2 S-cyclopropyl amino acid amino acid OH NH2 F amino acid amino acid OH NH2 C1 amino acid amino acid OH NH2 Br amino acid amino acid OH NH2 I amino acid H OH NH2 H amino acid H OH NH2 NH2 amino acid H OH NH2 NH-cyclopropyl amino acid H OH NH2 NH-methyl v amino acid OH NH2 NH-ethyl amino acid H OH NH2 NH-acetyl R R X X Y amino acid H OH NH2 OH amino acid H OH NH2 OMe amino acid H OH NH2 OEt amino acid H 0-cyclopropyl amino acid H OH NHz O-acetyl amino acid H OH NH2 SH amino acid H OH NH2 SMe amino acid H OH NH2 SEt amino acid H OH NH2 S-cyclopropyl amino acid H OH NH2 F amino acid H OH NH2 Cl amino acid H OH NH2 Br amino acid H OH NH2 I amino acid acyl OH NH2 H amino acid acyl OH NH2 NH2 amino acid acyl OH NH2 NH-cyclopropyl amino acid acyl OH NH2 NH-methyl amino acid acyl OH NH2 NH-ethyl amino acid acyl OH NH2 NH-acetyl amino acid acyl OH NH2 OH amino acid acyl OH NH2 OMe amino acid acyl OH NH2 OEt amino acid acyl OH NH2 O-cyclopropyl amino acid acyl_ OH NH2 O-acetyl amino acid acyl OH NH2 SH amino acid acyl OH NH2 SMe amino acid acyl OH NH2 SEt amino acid acyl OH NH2 S-cyclopropyl amino acid acyl OH NH2 F amino acid acyl OH NH2 C1 amino acid acyl OH NH2 Br amino acid acyl OH NH2 I acyl H OH H H acyl H OH H NH2 acyl H OH H NH-cyclopropyl acyl H OH H NH-methyl acyl H OH H NH-ethyl acyl H OH H NH-acetyl acyl H OH H OH acyl H OH H OMe acyl H OH H OEt acyl H OH H 0-cyclopropyl acyl H OH H 0-acetyl acyl H OH H SH acyl H OH H sme acyl H OH H SEt acyl H OH H S-cyclopropyl R R X X Y acyl OH H F acyl H OH H Cl acyl H OH H Br acyl H OH H I acyl acyl OH H H acyl acyl OH H NH2 acyl acyl OH H NH-cyclopropyl acyl acyl OH H NH-methyl acyl acyl OH H NH-ethyl acyl acyl OH H NH-acetyl S acyl acyl OH H OH acyl acyl OH H OMe acyl acyl OH H OEt acyl acyl OH H O-cyclopropyl acyl acyl OH H 0-acetyl acyl acyl OH H SH acyl acyl OH H SMe acyl acyl OH H SEt acyl acyl OH H S-cyclopropyl acyl acyl OH H F acyl acyl OH H C1 acyl acyl OH H Br acyl acyl OH H I acyl amino acid OH H H acyl amino acid OH H NH2 ac 1 amino acid OH H NH-c clo ro 1 acyl amino acid OH H NH-methyl acyl amino acid OH H NH-ethyl acyl amino acid OH H NH-acetyl acyl amino acid OH H OH acyl amino acid OH H OMe acyl amino acid OH H OEt acyl amino acid OH H 0-cyclopropyl acyl amino acid OH H 0-acetyl acyl amino acid OH H SH acyl amino acid OH H SMe acyl amino acid OH H SEt acyl amino acid OH H S-cyclopropyl acyl amino acid OH H F acyl amino acid OH H Cl acyl amino acid OH H Br acyl amino acid OH H I H acyl OH H H H acyl OH H NH2 H acyl OH H NH-cyclopropyl H acyl OH H NH-methyl H acyl OH H NH-ethyl R R. X X Y H acyl OH H NH-acetyl H acyl OH H OH H acyl OH H OMe H acyl OH H OEt H ac 1 OH H O-c clo ro 1 H acyl OH H O-acetyl H acyl OH H s H acyl OH H SMe H acyl OH H SEt H acyl OH H S-cyclopropyl H acyl OH H F H acyl OH H C1 H acyl OH H Br H acyl OH H I H amino acid OH H H H amino acid OH H NH2 H amino acid OH H NH-cyclopropyl H amino acid OH H NH-methyl H amino acid OH H NH-ethyl H amino acid OH H NH-acetyl H amino acid OH H OH H amino acid OH H OMe amino acid OH H OEt H amino acid OH H 0-cyclopropyl H amino acid OH H O-acetyl H amino acid OH H SH H amino acid OH H SMe H amino acid OH H SEt H amino acid OH H S-cyclopropyl H amino acid OH H F H amino acid OH H C1 amino acid OH H Br H amino acid OH H I amino acid amino acid OH H H amino acid amino acid OH H NH2 amino acid amino acid OH H NH-cyclopropyl amino acid amino acid OH H NH-methyl amino acid amino acid OH H NH-ethyl amino acid amino acid OH H NH-acetyl amino acid amino acid OH H OH amino acid amino acid OH H OMe amino acid amino acid OH H OEt amino acid amino acid OH H 0-cyclopropyl amino acid amino acid OH H 0-acetyl amino acid amino acid OH H SH amino acid amino acid OH H SMe amino acid amino acid OH H SEt R'R"X'X'Y amino acid amino acid OH H S-cyclopropyl amino acid amino acid OH H F amino acid amino acid OH H Cl amino acid amino acid OH H Br amino acid amino acid OH H I amino acid H OH H H amino acid H OH H NH2 amino acid H OH H NH-cyclopropyl amino acid H OH H NH-methyl amino acid H OH H NH-ethyl amino acid H OH H NH-acetyl amino acid H OH H OH amino acid H OH H OMe amino acid H OH H OEt amino acid H 0-cyclopropyl amino acid H OH H O-acetyl amino acid H OH H SH amino acid H OH H SMe amino acid H OH H SEt amino acid H OH H S-cyclopropyl amino acid H OH H F amino acid H OH H C1 amino acid H OH H Br amino acid H OH H I amino acid acyl OH H H amino acid acyl OH H NH2 amino acid acyl OH H NH-cyclopropyl amino acid acyl OH H NH-methyl amino acid acyl OH H NH-ethyl amino acid acyl OH H NH-acetyl amino acid acyl OH H OH amino acid acyl OH H OMe amino acid acyl OH H OEt amino acid acyl OH H 0-cyclopropyl amino acid acyl OH H 0-acetyl amino acid acyl OH H SH amino acid acyl OH H SMe amino acid acyl OH H SEt amino acid acyl OH H S-cyclopropyl amino acid acyl OH H F amino acid acyl OH H Cl amino acid acyl OH H Br amino acid acyl OH H I acyl H OH OH H acyl H OH OH NH2 acyl H OH OH NH-cyclopropyl acyl H OH OH NH-methyl R2 R3 Xl XZ acyl H OH OH NH-ethyl acyl H OH OH NH-acetyl acyl H OH OH OH acyl H OH OH OMe acyl H OH OH OEt acyl H OH OH 0-cyclopropyl acyl H OH OH 0-acetyl acyl H OH OH SH acyl H OH OH SMe acyl H OH OH SEt acyl H OH OH S-cyclopropyl acyl H OH OH F acyl H OH OH ci acyl H OH OH Br acyl H OH OH I acyl acyl OH OH H acyl acyl OH OH NH2 acyl acyl OH OH NH-cyclopropyl acyl acyl OH OH NH-methyl acyl acyl OH OH NH-ethyl acyl acyl OH OH NH-acetyl acyl acyl OH OH OH acyl acyl OH OH OMe acyl acyl OH OH OEt acyl acyl OH OH 0-cyclopropyl acyl acyl OH OH 0-acetyl acyl acyl OH OH SH acyl acyl OH OH SMe acyl acyl OH OH SEt acyl acyl OH OH S-cyclopropyl acyl acyl OH OH F acyl acyl OH OH ci acyl acyl OH OH Br acyl acyl OH OH I acyl amino acid OH OH H acyl amino acid OH OH NH2 acyl amino acid OH OH NH-cyclopropyl acyl amino acid OH OH NH-methyl acyl amino acid OH OH NH-ethyl acyl amino acid OH OH NH-acetyl acyl amino acid OH OH OH acyl amino acid OH OH OMe acyl amino acid OH OH OEt acyl amino acid OH OH 0-cyclopropyl acyl amino acid OH OH 0-acetyl acyl amino acid OH OH SH acyl arnino acid OH OH SMe R R X X Y acyl amino acid OH OH SEt acyl amino acid OH OH S-cyclopropyl acyl amino acid OH OH F acyl amino acid OH OH Cl acyl amino acid OH OH Br acyl amino acid OH OH I H acyl OH OH H H acyl OH OH NH2 H acyl OH OH NH-cyclopropyl H acyl OH OH NH-methyl H acyl OH OH NH-ethyl H acyl OH OH NH-acetyl H acyl OH OH OH H acyl OH OH OMe H acyl OH OH OEt H acyl OH OH 0-cyclopropyl H acyl OH OH 0-acetyl H acyl OH OH SH H acyl OH OH SMe H acyl OH OH SEt H acyl OH OH S-cyclopropyl H acyl OH OH F H acyl OH OH ci H acyl OH OH Br H acyl OH OH I H amino acid OH OH H H amino acid OH OH NH2 H amino acid OH OH NH-cyclopropyl H amino acid OH OH NH-methyl H amino acid OH OH NH-ethyl H amino acid OH OH NH-acetyl H amino acid OH OH OH H amino acid OH OH OMe H amino acid OH OH OEt H amino acid OH OH 0-cyclopropyl H amino acid OH OH 0-acetyl H amino acid OH OH SH H amino acid OH OH SMe H amino acid OH OH SEt H amino acid OH OH _ S-cyclopropyl _ H amino acid OH OH F H amino acid OH OH Cl H amino acid OH OH Br H amino acid OH OH I amino acid amino acid OH OH H amino acid amino acid OH OH NH2 amino acid amino acid OH OH NH-cyclopropyl R R X X Y amino acid amino acid OH OH NH-methyl amino acid amino acid OH OH NH-ethyl amino acid amino acid OH OH NH-acetyl amino acid amino acid OH OH OH amino acid amino acid OH OH OMe amino acid amino acid OH OH OEt amino acid amino acid OH OH 0-cyclopropyl amino acid amino acid OH OH 0-acetyl amino acid amino acid OH OH SH amino acid amino acid OH OH SMe amino acid amino acid OH OH SEt amino acid amino acid OH OH S-cyclopropyl amino acid amino acid OH OH F amino acid amino acid OH OH Cl amino acid amino acid OH OH Br amino acid amino acid OH OH I amino acid H OH OH H amino acid H OH OH NH2 amino acid H OH OH NH-cyclopropyl amino acid H OH OH NH-methyl amino acid H OH OH NH-ethyl amino acid H OH OH NH-acetyl amino acid H OH OH OH amino acid H OH OH OMe amino acid H OH OH OEt amino acid H OH OH 0-cyclopropyl amino acid H OH OH 0-acetyl amino acid H OH OH SH amino acid H OH OH SMe amino acid H OH OH SEt amino acid H OH OH S-cyclopropyl amino acid H OH OH F amino acid H OH OH Cl amino acid H OH OH Br amino acid H OH OH I amino acid acyl OH OH H amino acid acyl OH OH NH2 amino acid acyl OH OH NU-cyclopropyl amino acid acyl OH OH NH-methyl amino acid acyl OH OH NH-ethyl amino acid acyl OH OH NH-acetyl amino acid acyl OH OH OH amino acid acyl OH OH OMe amino acid acyl OH OH OEt amino acid acyl OH OH 0-cyclopropyl amino acid acyl OH OH O-acetyl amino acid acyl OH OH SH R R Xl X Y amino acid acyl OH OH SMe amino acid acyl OH OH SEt amino acid acyl OH OH S-cyclopropyl amino acid acyl OH OH F amino acid acyl OH OH C1 amino acid acyl OH OH Br amino acid acyl OH OH I acyl H H OH H acyl H H OH NH2 ac 1 H H OH NH-c clo ro 1 acyl H H OH NH-methyl acyl H H OH NH-ethyl acyl H H OH NH-acetyl acyl H H OH OH acyl H H OH OMe acyl H H OH OEt acyl H H OH 0-cyclopropyl acyl H H OH 0-acetyl acyl H H OH SH acyl H H OH SMe acyl H H OH SEt acyl H H OH S-cyclopropyl acyl H H OH F acyl H H OH Cl acyl H H OH Br acyl H H OH I acyl acyl H OH H acyl acyl H OH NH2 ac 1 acyl H OH NH-c clo ro 1 acyl acyl H OH NH-methyl acyl acyl H OH NH-ethyl acyl acyl H OH NH-acetyl acyl acyl H OH OH acyl acyl H OH OMe acyl acyl H OH OEt acyl acyl H OH O-cyclopropyl acyl acyl H OH 0-acetyl acyl acyl H OH SH acyl acyl H OH SMe acyl acyl H OH SEt x acyl acyl H OH S-cyclopropyl acyl acyl H OH F acyl acyl H OH C1 acyl acyl H OH Br acyl acyl H OH I acyl amino acid H OH H acyl amino acid H OH NH2 R2 R X X Y acyl amino acid H OH NH-cyclopropyl acyl amino acid H OH NH-methyl acyl amino acid H OH NH-ethyl acyl amino acid H OH NH-acetyl acyl amino acid H OH OH acyl amino acid H OH OMe acyl amino acid H OH OEt acyl amino acid H OH 0-cyclopropyl acyl amino acid H OH O-acetyl acyl amino acid H OH SH acyl amino acid H OH SMe acyl amino acid H OH SEt acyl amino acid H OH S-cyclopropyl acyl amino acid H OH F acyl amino acid H OH Cl acyl amino acid H OH Br acyl amino acid H OH I H acyl H OH H H acyl H OH NH2 H acyl H OH NH-cyclopropyl H acyl H OH NH-methyl H acyl H OH NH-ethyl H acyl H OH NH-acetyl acyl H OH OH H acyl H OH OMe H acyl H OH OEt H acyl H OH 0-cyclopropyl H acyl H OH O-acetyl H acyl H OH SH H acyl H OH SMe H acyl H OH SEt H acyl H OH S-cyclopropyl H acyl H OH F H acyl H OH C1 S H acyl H OH Br H acyl H OH I H amino acid H OH H H amino acid H OH NH2 H amino acid H OH NH-cyclopropyl H amino acid H OH NH-methyl H amino acid H OH NH-ethyl H amino acid H OH NH-acetyl H amino acid H OH OH H amino acid H OH OMe H amino acid H OH OEt H amino acid H OH 0-cyclopropyl H amino acid H OH 0-acetyl R R3 |XI X2 H amino acid H OH SH H amino acid H OH SMe H amino acid H OH SEt H amino acid H OH S-cyclopropyl H amino acid H OH F H amino acid H OH Cl H amino acid H OH Br H amino acid H OH I amino acid amino acid H OH H amino acid amino acid H OH NH2 amino acid amino acid H OH NH-cyclopropyl amino acid amino acid H OH NH-methyl amino acid amino acid H OH NH-ethyl amino acid amino acid H OH NH-acetyl amino acid amino acid H OH OH amino acid amino acid H OH OMe amino acid amino acid H OH OEt amino acid amino acid H OH 0-cyclopropyl amino acid amino acid H OH 0-acetyl amino acid amino acid H OH SH amino acid amino acid H OH SMe amino acid amino acid H OH SEt amino acid amino acid H OH S-cyclopropyl amino acid amino acid H OH F amino acid amino acid H OH ci amino acid amino acid H OH Br amino acid amino acid H OH I amino acid H H OH H amino acid H H OH NH2 amino acid H H OH NH-cyclopropyl amino acid H H OH NH-methyl amino acid H H OH NH-ethyl amino acid H H OH NH-acetyl # amino acid H H OH OH amino acid H H OH OMe amino acid H H OH OEt amino acid H 0-cyclopropyl amino acid H H OH 0-acetyl amino acid H H OH SH amino acid H H OH SMe amino acid H H OH SEt amino acid H H OH S-cyclopropyl amino acid H H OH F amino acid H H OH Cl amino acid H H OH Br amino acid H H OH I amino acid acyl H OH H R R3 Xl x2 amino acid acyl H OH NH2 amino acid acyl H OH NH-cyclopropyl amino acid acyl H OH NH-methyl amino acid acyl H OH NH-ethyl amino acid acyl H OH NH-acetyl amino acid acyl H OH OH amino acid acyl H OH OMe amino acid acyl H OH OEt amino acid acyl H OH 0-cyclopropyl amino acid acyl H OH 0-acetyl amino acid acyl H OH SH amino acid acyl H OH SMe amino acid acyl H OH SEt amino acid acyl H OH S-cyclopropyl amino acid acyl H OH F amino acid acyl H OH ci amino acid acyl H OH Br amino acid acyl H OH I acyl H OH SH H acyl H OH SH NH2 acyl H OH SH NH-cyclopropyl acyl H OH SH NH-methyl acyl H OH SH NH-ethyl acyl H OH SH NH-acetyl acyl H OH SH OH acyl H OH SH OMe acyl H OH SH OEt acyl H OH SH 0-cyclopropyl acyl H OH SH 0-acetyl acyl H OH SH SH acyl H OH SH SMe acyl OH SH SEt acyl H OH SH S-cyclopropyl acyl H OH SH F acyl H OH SH ci acyl H OH SH Br acyl H OH SH I acyl acyl OH SH H acyl acyl OH SH NH2 acyl acyl OH SH NH-cyclopropy1 acyl acyl OH SH NH-methyl acyl acyl OH SH NH-ethyl acyl acyl OH SH NH-acetyl acyl acyl OH SH OH acyl acyl OH SH OMe acyl acyl OH SH OEt acyl acyl OH SH 0-cyclopropyl R2 R3 Xl x2 acyl acyl OH SH 0-acetyl acyl acyl OH SH SH acyl acyl OH SH SMe acyl acyl OH SH SEt acyl acyl OH SH S-cyclopropyl acyl acyl OH SH F acyl acyl OH SH ci acyl acyl OH SH Br acyl acyl OH SH I acyl amino acid OH SH H acyl amino acid OH SH NHZ acyl amino acid OH SH NH-c clo ro yl acyl amino acid OH SH NH-methyl acyl amino acid OH SH NH-ethyl acyl amino acid OH SH NH-acetyl acyl amino acid OH SH OH acyl amino acid OH SH OMe acyl amino acid OH SH OEt acyl amino acid OH SH 0-cyclopropyl acyl amino acid OH SH 0-acetyl f acyl amino acid OH SH SH acyl amino acid OH SH SMe acyl amino acid OH SH SEt acyl amino acid OH SH S-cyclopropyi acyl amino acid OH SH F acyl amino acid OH SH Cl acyl amino acid OH SH Br acyl amino acid OH SH I H acyl OH SH H H acyl OH SH NH2 H acyl OH SH NH-cyclopropyl H acyl OH SH NH-methyl H acyl OH SH NH-ethyl H acyl OH SH NH-acetyl H acyl OH SH OH H acyl OH SH OMe H acyl OH SH OEt H acyl OH SH 0-cyclopropyl H acyl OH SH 0-acetyl H acyl OH SH SH H acyl OH SH SMe H acyl OH SH SEt H acyl OH SH S-cyclopropyl H acyl OH SH F H acyl OH SH ci H acyl OH SH Br H acyl OH SH I R2 R3 X1 X2 Y H amino acid OH SH H H amino acid OH SH NH2 H amino acid OH SH NH-cyclopropyl H amino acid OH SH NH-methyl amino acid OH SH NH-ethyl H amino acid OH SH NH-acetyl H amino acid OH SH OH amino acid OH SH OMe amino acid OH SH OEt H amino acid OH SH 0-cyclopropyl H amino acid OH SH 0-acetyl amino acid OH SH SH amino acid OH SH SMe amino acid OH SH SEt amino acid OH SH S-cyclopropyl amino acid OH SH F amino acid OH SH Cl amino acid OH SH Br amino acid OH SH I amino acid amino acid OH SH H amino acid amino acid OH SH NH2 amino acid amino acid OH SH NH-cyclopropyl amino acid amino acid OH SH NH-methyl amino acid amino acid OH SH NH-ethyl amino acid amino acid OH SH NH-acetyl amino acid amino acid OH SH OH amino acid amino acid OH SH OMe amino acid amino acid OH SH OEt amino acid amino acid OH SH 0-cyclopropyl amino acid amino acid OH SH 0-acetyl amino acid amino acid OH SH SH amino acid amino acid OH SH SMe amino acid amino acid OH SH SEt amino acid amino acid OH SH S-cyclopropyl amino acid amino acid OH SH amino acid amino acid OH SH Cl amino acid amino acid OH SH Br amino acid amino acid OH SH I amino acid H OH SH H amino acid H OH SH NHz amino acid H OH SH NH-cyclopropyl amino acid H OH SH NH-methyl s amino acid H OH SH NH-ethyl amino acid H OH SH NH-acetyl amino acid H OH SH OH amino acid OH SH OMe amino acid H OH SH OEt R2 R3 Xl x2 amino acid H OH SH 0-cyclopropyl amino acid H OH SH 0-acetyl amino acid H OH SH SH amino acid H OH SH SMe amino acid H OH SH SEt amino acid H OH SH S-cyclopropyl amino acid H OH SH F amino acid H OH SH Cl amino acid H OH SH Br amino acid H OH SH I amino acid acyl OH SH H amino acid acyl OH SH NH2 amino acid acyl OH SH NH-cyclopropyl amino acid acyl OH SH NH-methyl amino acid acyl OH SH NH-ethyl amino acid acyl OH SH NH-acetyl amino acid acyl OH SH OH amino acid acyl OH SH OMe amino acid acyl OH SH OEt amino acid acyl OH SH 0-cyclopropyl amino acid acyl OH SH 0-acetyl amino acid acyl OH SH SH amino acid acyl OH SH SMe amino acid acyl OH SH SEt amino acid acyl OH SH S-cyclopropyl amino acid acyl OH SH F amino acid acyl OH SH Cl amino acid acyl OH SH Br amino acid acyl OH SH I acyl H SH OH H acyl H SH OH NH2 acyl H SH OH NH-cyclopropyl acyl H SH OH NH-methyl acyl H SH OH NH-ethyl acyl H SH OH NH-acetyl acyl H SH OH OH acyl H SH OH OMe acyl H SH OH OEt ac 1 H SH OH O-c clo ro 1 acyl H SH OH 0-acetyl acyl H SH OH SH acyl H SH OH SMe acyl H SH OH SEt acyl H SH OH S-cyclopropyl acyl H SH OH F acyl H SH OH ci acyl H SH OH Br R2 R3 Xl x2 acyl H SH OH I acyl acyl SH OH H acyl acyl SH OH NH2 acyl acyl SH OH NH-cyclopropyl acyl acyl SH OH NH-methyl acyl acyl SH OH NH-ethyl acyl acyl SH OH NH-acetyl acyl acyl SH OH OH acyl acyl SH OH OMe acyl acyl SH OH OEt acyl acyl SH OH O-cyclopropyl acyl acyl SH OH 0-acetyl acyl acyl SH OH SH acyl acyl SH OH SMe acyl acyl SH OH SEt acyl acyl SH OH S-cyclopropyl acyl acyl SH OH F acyl acyl SH OH Cl acyl acyl SH OH Br acyl acyl SH OH I acyl amino acid SH OH H acyl amino acid SH OH NH2 acyl amino acid SH OH NH-cyclopropyl acyl amino acid SH OH NH-methyl acyl amino acid SH OH NH-ethyl acyl amino acid SH OH NH-acetyl acyl amino acid SH OH OH acyl amino acid SH OH OMe acyl amino acid SH OH OEt acyl amino acid SH OH 0-cyclopropyl P PY acyl amino acid SH OH 0-acetyl acyl amino acid SH OH SH acyl amino acid SH OH SMe acyl amino acid SH OH SEt acyl amino acid SH OH S-cyclopropyl acyl amino acid SH OH F acyl amino acid SH OH Cl acyl amino acid SH OH Br acyl amino acid SH OH I H acyl SH OH H H acyl SH OH NH2 H acyl SH OH NH-cyclopropyl H acyl SH OH NH-methyl H acyl SH OH NH-ethyl H acyl SH OH NH-acetyl H acyl SH OH OH H acyl SH OH OMe R R X X Y H acyl SH OH OEt H ac 1 SH OH O-c clo ro 1 H acyl SH OH 0-acetyl f H acyl SH OH SH H acyl SH OH SMe H acyl SH OH SEt H acyl SH OH S-cyclopropyl H acyl SH OH F H acyl SH OH ci H acyl SH OH Br H acyl SH OH H amino acid SH OH H H amino acid SH OH NH2 H amino acid SH OH NH-cyclopropyl H amino acid SH OH NH-methyl H arnino acid SH OH NH-ethyl H amino acid SH OH NH-acetyl H amino acid SH OH OH H amino acid SH OH OMe H amino acid SH OH OEt H amino acid SH OH 0-cyclopropyl H amino acid SH OH O-acetyl H amino acid SH OH SH H amino acid SH OH SMe H amino acid SH OH SEt H amino acid SH OH S-cyclopropyl H amino acid SH OH F H amino acid SH OH Cl H amino acid SH OH Br H amino acid SH OH I amino acid amino acid SH OH H amino acid amino acid SH OH NH2 amino acid amino acid SH OH NH-cyclopropyl amino acid amino acid SH OH NH-methyl amino acid amino acid SH OH NH-ethyl amino acid amino acid SH OH NH-acetyl amino acid amino acid SH OH OH amino acid amino acid SH OH OMe amino acid amino acid SH OH OEt amino acid amino acid SH OH 0-cyclopropyl amino acid amino acid SH OH 0-acetyl amino acid amino acid SH OH SH amino acid amino acid SH OH SMe amino acid amino acid SH OH SEt amino acid amino acid SH OH S-cyclopropyl amino acid amino acid SH OH F amino acid amino acid SH OH Cl R2 R3 X1 x2 amino acid amino acid SH OH Br amino acid amino acid SH OH I amino acid H SH OH H amino acid H SH OH NH2 amino acid H SH OH NH-cyclopropyl amino acid H SH OH NH-methyl amino acid H SH OH NH-ethyl amino acid H SH OH NH-acetyl amino acid H SH OH OH amino acid H SH OH OMe amino acid H SH OH OEt amino acid H SH OH 0-cyclopropyl amino acid H SH OH O-acetyl amino acid H SH OH SH amino acid H SH OH SMe amino acid H SH OH SEt amino acid H SH OH S-cyclopropyl amino acid H SH OH F amino acid H SH OH ci amino acid H SH OH Br amino acid H SH OH I amino acid acyl SH OH H amino acid acyl SH OH NH2 amino acid acyl SH OH NH-cyclopropyl amino acid acyl SH OH NH-methyl amino acid acyl SH OH NH-ethyl amino acid acyl SH OH NH-acetyl amino acid acyl SH OH OH amino acid acyl SH OH OMe amino acid acyl SH OH OEt amino acid acyl SH OH 0-cyclopropyl amino acid acyl SH OH 0-acetyl amino acid acyl SH OH SH amino acid acyl SH OH SMe amino acid acyl SH OH SEt amino acid acyl SH OH S-cyclopropyl amino acid acyl SH OH F amino acid acyl SH OH Cl amino acid acyl SH OH Br amino acid acyl SH OH I acyl Br H H acyl H Br H NH2 acyl H Br H NH-cyclopropyl acyl H Br H NH-methyl acyl H Br H NH-ethyl acyl H Br H NH-acetyl acyl H Br H OH R2 R X X Y acyl H Br H OMe acyl H Br H OEt acyl H Br H 0-cyclopropyl acyl H Br H 0-acetyl acyl H Br H SH acyl H Br H SMe acyl H Br H SEt acyl H Br H S-cyclopropyl acyl H Br H F acyl H Br H C1 acyl H Br H Br acyl H Br H acyl acyl Br H H acyl acyl Br H NH2 acyl acyl Br H NH-c clo ro yl acyl acyl Br H NH-methyl acyl acyl Br H NH-ethyl acyl acyl Br H NH-acetyl acyl acyl Br H OH acyl acyl Br H OMe acyl acyl Br H OEt acyl acyl Br H O-cyclopropyl acyl acyl Br H 0-acetyl acyl acyl Br H SH acyl acyl Br H SMe acyl acyl Br H SEt acyl acyl Br H S-cyclopropyl acyl acyl Br H F acyl acyl Br H C1 acyl acyl Br H Br acyl acyl Br H I acyl amino acid Br H H acyl amino acid Br H NH2 acyl amino acid Br H NH-cyclopropyl acyl amino acid Br H NH-methyl acyl amino acid Br H NH-ethyl acyl amino acid Br H NH-acetyl acyl amino acid Br H OH acyl arnino acid Br H OMe acyl amino acid Br H OEt acyl amino acid Br H 0-cyclopropyl acyl amino acid Br H 0-acetyl acyl amino acid Br H SH acyl amino acid Br H SMe acyl amino acid Br H SEt acyl amino acid Br H S-cyclopropyl acyl amino acid Br H F R R w X Y acyl amino acid Br H Cl acyl amino acid Br H Br acyl amino acid Br H I H acyl Br H H H acyl Br H NH2 H ac 1 Br H NH-c clo ro 1 H acyl Br H NH-methyl H acyl Br H NH-ethyl H acyl Br H NH-acetyl H acyl Br H OH H acyl Br H OMe H acyl Br H OEt H acyl Br H 0-cyclopropyl H acyl Br H 0-acetyl H acyl Br H SH H acyl Br H SMe H acyl Br H SEt H acyl Br H S-cyclopropyl H acyl Br H F H acyl Br H C1 H acyl Br H Br H acyl Br H I H amino acid Br H H H amino acid Br H NH2 H amino acid. Br H NH-c clo ro yl H amino acid Br H NH-methyl H amino acid Br H NH-ethyl H amino acid Br H NH-acetyl H amino acid Br H OH H amino acid Br H OMe H amino acid Br H OEt H amino acid Br H 0-cyclopropyl H amino acid Br H 0-acetyl H amino acid Br H SH H amino acid Br H SMe H amino acid Br H SEt H amino acid Br H S-cyclopropyl H amino acid Br H F H amino acid Br H Cl H amino acid Br H Br H amino acid Br H I amino acid amino acid Br H H amino acid amino acid Br H NH2 amino acid amino acid Br H NH-cyclopropyl amino acid amino acid Br H NH-methyl amino acid amino acid Br H NH-ethyl amino acid amino acid Br H NH-acetyl R R X X Y amino acid amino acid Br H OH amino acid amino acid Br H OMe amino acid amino acid Br H OEt amino acid amino acid Br H O-c clo ro 1 amino acid amino acid Br H O-acetyl amino acid amino acid Br H SH amino acid amino acid Br H SMe amino acid amino acid Br H SEt amino acid amino acid Br H S-cyclopropyl amino acid amino acid Br H F amino acid amino acid Br H Cl amino acid amino acid Br H Br amino acid amino acid Br H I amino acid H Br H H amino acid H Br H NH2 amino acid H Br H NH-c clo ro yl amino acid H Br H NH-methyl amino acid H Br H NH-ethyl amino acid H Br H NH-acetyl amino acid H Br H OH amino acid H Br H OMe amino acid H Br H OEt amino acid H 0-cyclopropyl amino acid H Br H 0-acetyl amino acid H Br H SH amino acid H Br H SMe amino acid H Br H SEt amino acid H Br H S-cyclopropyl amino acid H Br H F amino acid H Br H Cl amino acid H Br H Br amino acid H Br H I amino acid acyl Br H H amino acid acyl Br H NH2 amino acid acyl Br H NH-cyclo ro yl amino acid acyl Br H NH-methyl amino acid acyl Br H NH-ethyl amino acid acyl Br H NH-acetyl amino acid acyl Br H OH amino acid acyl Br H OMe amino acid acyl Br H OEt amino acid ac 1 Br H O-c clo ro 1 amino acid acyl Br H 0-acetyl amino acid acyl Br H SH amino acid acyl Br H SMe amino acid acyl Br H SEt amino acid acyl Br H S-cyclopropyl R R X X Y amino acid acyl Br H F amino acid acyl Br H Cl amino acid acyl Br H Br amino acid acyl Br H I acyl H Br Br H acyl H Br Br NH2 acyl H Br Br NH-c clo ro yl acyl H Br Br NH-methyl acyl H Br Br NH-ethyl acyl H Br Br NH-acetyl acyl H Br Br OH acyl H Br Br OMe acyl H Br Br OEt acyl H Br Br 0-cyclopropyl acyl H Br Br O-acetyl acyl H Br Br SH acyl H Br Br SMe acyl H Br Br SEt acyl H Br Br S-cyclopropyl acyl H Br Br F acyl H Br Br C1 acyl H Br Br Br acyl H Br Br I acyl acyl Br Br H acyl acyl Br Br NH2 acyl acyl Br Br NH-cyclopropyl acyl acyl Br Br NH-methyl acyl acyl Br Br NH-ethyl acyl acyl Br Br NH-acetyl acyl acyl Br Br OH acyl acyl Br Br OMe acyl acyl Br Br OEt acyl acyl Br Br 0-cyclopropyl acyl acyl Br Br 0-acetyl acyl acyl Br Br SH acyl acyl Br Br SMe acyl acyl Br Br SEt acyl acyl Br Br S-cyclopropyl acyl acyl Br Br F acyl acyl Br Br Cl acyl acyl Br Br Br acyl acyl Br Br I acyl amino acid Br Br H acyl amino acid Br Br NH2 acyl amino acid Br Br NH-cyclopropyl acyl amino acid Br Br NH-methyl acyl amino acid Br Br NH-ethyl R2 R3 Xl x2 acyl amino acid Br Br NH-acetyl acyl amino acid Br Br OH acyl amino acid Br Br OMe acyl amino acid Br Br OEt acyl amino acid Br 0-cyclopropyl acyl amino acid Br Br 0-acetyl acyl amino acid Br Br SH acyl amino acid Br Br SMe acyl amino acid Br Br SEt acyl amino acid Br Br S-cyclopropyl acyl amino acid Br Br F acyl amino acid Br Br Cl acyl amino acid Br Br Br acyl amino acid Br Br I H acyl Br Br H H acyl Br Br NH2 H acyl Br Br NH-cyclopropyl H acyl Br Br NH-methyl H acyl Br Br NH-ethyl H acyl Br Br NH-acetyl H acyl Br Br OH H acyl Br Br OMe H acyl Br Br OEt H acyl Br 0-cyclopropyl H acyl Br Br 0-acetyl H acyl Br Br SH H acyl Br Br SMe H acyl Br Br SEt H acyl Br Br S-cyclopropyl H acyl Br Br F H ar-yl Br Br ci H acyl Br Br Br H acyl Br Br I H amino acid Br Br H H amino acid Br Br NH2 H amino acid Br Br NH-cyclopropyl H amino acid Br Br NH-methyl H amino acid Br Br NH-ethyl H amino acid Br Br NH-acetyl H amino acid Br Br OH H amino acid Br Br OMe H amino acid Br Br OEt H amino acid Br Br 0-cyclopropyl H amino acid Br Br 0-acetyl H amino acid Br Br SH H amino acid Br Br SMe H amino acid Br Br SEt R2 R3 Xl XZ- H amino acid Br Br S-cyclopropyl H amino acid Br Br F H amino acid Br Br Cl H amino acid Br Br Br H amino acid Br Br I amino acid amino acid Br Br H amino acid amino acid Br Br NH2 amino acid amino acid Br Br NH-cyclopropyl amino acid amino acid Br Br NH-methyl amino acid amino acid Br Br NH-ethyl amino acid amino acid Br Br NH-acetyl amino acid amino acid Br Br OH amino acid amino acid Br Br OMe amino acid amino acid Br Br OEt amino acid amino acid Br Br 0-cyclopropyl amino acid amino acid Br Br 0-acetyl amino acid amino acid Br Br SH amino acid amino acid Br Br SMe amino acid amino acid Br Br SEt amino acid amino acid Br Br S-cyclopropyl amino acid amino acid Br Br F amino acid amino acid Br Br Cl amino acid amino acid Br Br Br amino acid amino acid Br Br I amino acid H Br Br H amino acid H Br Br NH2 amino acid H Br Br NH-cyclopropyl S amino acid H Br Br NH-methyl amino acid H Br Br NH-ethyl amino acid H Br Br NH-acetyl amino acid H Br Br OH amino acid H Br Br OMe amino acid H Br Br OEt amino acid H Br Br 0-cyclopropyl #. v amino acid H Br Br O-acetyl amino acid H Br Br SH amino acid H Br Br SMe amino acid H Br Br SEt amino acid H Br Br S-cyclopropyl amino acid H Br Br F amino acid H Br Br Cl amino acid H Br Br Br amino acid H Br Br I amino acid acyl Br Br H amino acid acyl Br Br NH2 amino acid acyl Br Br NH-cyclopropyl amino acid acyl Br Br NH-methyl R R X X Y amino acid acyl Br Br NH-ethyl amino acid acyl Br Br NH-acetyl amino acid acyl Br Br OH amino acid acyl Br Br OMe amino acid acyl Br Br OEt amino acid acyl Br Br 0-cyclopropyl amino acid acyl Br Br 0-acetyl amino acid acyl Br Br SH amino acid acyl Br Br SMe amino acid acyl Br Br SEt amino acid acyl Br Br S-cyclopropyl amino acid acyl Br Br F amino acid acyl Br Br ci amino acid acyl Br Br Br amino acid acyl Br Br I acyl H H Br H acyl H H Br NH2 acyl H H Br NH-cyclopropyl acyl H H Br NH-methyl acyl H H Br NH-ethyl acyl H H Br NH-acetvl acyl H H Br OH acyl H H Br OMe acyl H H Br OEt acyl H H Br O-cyclopropyl acyl H H Br 0-acetyl acyl H H Br SH acyl H H Br SMe acyl H H Br SEt acyl H H Br S-cyclopropyl acyl H H Br F acyl H H Br C1 acyl H H Br Br acyl H H Br I acyl acyl H Br H acyl acyl H Br NH2 acyl acyl H Br NH-cyclopropyl acyl acyl H Br NH-methyl acyl acyl H Br NH-ethyl acyl acyl H Br NH-acetyl acyl acyl H Br OH acyl acyl H Br OMe acyl acyl H Br OEt acyl acel H Br O-cyclooronvl acyl acyl H Br 0-acetyl acyl acyl H Br SH acyl acyl H Br SMe R R3 Xl X2 acyl acyl H Br SEt acyl acyl H Br S-cyclopropyl acyl acyl H Br F acyl acyl H Br C1 acyl acyl H Br Br acyl acyl H Br I acyl amino acid H Br H acyl amino acid H Br NH2 acyl amino acid H Br NH-cyclopropy1 acyl amino acid H Br NH-methyl acyl amino acid H Br NH-ethyl acyl amino acid H Br NH-acetyl acyl amino acid H Br OH acyl amino acid H Br OMe acyl amino acid H Br OEt acyl amino acid H Br 0-cyclopropyl acyl amino acid H Br 0-acetyl acyl amino acid H Br SH acyl amino acid H Br SMe acyl amino acid H Br SEt acyl amino acid H Br S-cyclopropyl acyl amino acid H Br F acyl amino acid H Br Cl acyl amino acid H Br Br acyl amino acid H Br I H acyl H Br H H acyl H Br NH2 H acyl H Br NH-cyclopropyl H acyl H Br NH-methyl H acyl H Br NH-ethyl H acyl H Br NH-acetyl H acyl H Br OH H acyl H Br OMe H acyl H Br OEt H acyl H Br 0-cyclopropyl s H acyl H Br 0-acetyl H acyl H Br SH H acyl H Br SMe H acyl H Br SEt H acyl H Br S-cyclopropyl H acyl H Br F H acyl H Br Cl H acyl H Br Br H acyl H Br I H amino acid H Br H H amino acid H Br NH2 H amino acid H Br NH-cyclopropyl R2-R3 Xl x2 H amino acid H Br NH-methyl H amino acid H Br NH-ethyl H amino acid H Br NH-acetyl H amino acid H Br OH H amino acid H Br OMe H amino acid H Br OEt H amino acid H Br 0-cyclopropyl H amino acid H Br 0-acetyl H amino acid H Br SH H amino acid H Br SMe H amino acid H Br SEt H amino acid H Br S-cyclopropyl H amino acid H Br F H amino acid H Br Cl H amino acid H Br Br H amino acid H Br I amino acid amino acid H Br H amino acid amino acid H Br NH2 amino acid amino acid H Br NH-cyclopropyl amino acid amino acid H Br NH-methyl amino acid amino acid H Br NH-ethyl amino acid amino acid H Br NH-acetyl amino acid amino acid H Br OH amino acid amino acid H Br OMe amino acid amino acid H Br OEt amino acid amino acid H Br 0-cyclopropyl amino acid amino acid H Br 0-acetyl amino acid amino acid H Br SH amino acid amino acid H Br SMe amino acid amino acid H Br SEt amino acid amino acid H Br S-cyclopropyl amino acid amino acid H Br F amino acid amino acid H Br Cl amino acid amino acid H Br Br amino acid amino acid H Br I amino acid H H Br H amino acid H H Br NH2 amino acid H H Br NH-cyclopropyl amino acid H H Br NH-methyl amino acid H H Br NH-ethyl amino acid H H Br NH-acetyl amino acid H H Br OH amino acid H H Br OMe amino acid H H Br OEt amino acid H 0-cyclopropyl amino acid H H Br 0-acetyl amino acid H H Br SH R R X X Y amino acid H H Br SMe amino acid H H Br SEt amino acid H H Br S-cyclopropyl amino acid H H Br F amino acid H H Br Cl amino acid H H Br Br amino acid H H Br I amino acid acyl H Br H amino acid acyl H Br NH2 amino acid acyl H Br NH-cyclopropyl amino acid acyl H Br NH-methyl amino acid acyl H Br NH-ethyl amino acid acyl H Br NH-acetyl amino acid acyl H Br OH amino acid acyl H Br OMe amino acid acyl H Br OEt amino acid acyl H Br O-cyclopropyl amino acid acyl H Br 0-acetyl amino acid acyl H Br SH amino acid acyl H Br SMe amino acid acyl H Br SEt amino acid acyl H Br S-cyclopropyl amino acid acyl H Br F amino acid acyl H Br Cl amino acid acyl H Br Br amino acid acyl H Br I acyl H C1 Br H acyl H C1 Br NH2 acyl H Cl Br NH-cyclopropyl acyl H C1 Br NH-methyl acyl H Cl Br NH-ethyl acyl H C1 Br NH-acetyl acyl H C1 Br OH acyl H C1 Br OMe acyl H C1 Br OEt acyl H Cl Br O-cyclopropyl acyl H Cl Br 0-acetyl acyl H C1 Br SH acyl H C1 Br SMe acyl H C1 Br SEt acyl H C1 Br S-cyclopropyl acyl H C1 Br F acyl H C1 Br C1 acyl H Cl Br Br acyl H C1 Br acyl acyl C1 Br H acyl acyl C1 Br NH2 R Xl X2 ~ acyl acyl C1 Br NH-cyclopropyl acyl acyl C1 Br NH-methyl acyl acyl C1 Br NH-ethyl acyl acyl C1 Br NH-acetyl acyl acyl C1 Br OH acyl acyl C1 Br OMe acyl acyl C1 Br OEt ac I ac 1 Cl Br O-c clo ro yl acyl acyl Cl Br O-acetyl acyl acyl C1 Br SH acyl acyl C1 Br SMe acyl acyl C1 Br SEt ac 1 ac 1 Cl Br S-c clo ro 1 acyl acyl C1 Br F acyl acyl C1 Br C1 acyl acyl C1 Br Br acyl acyl C1 Br I acyl amino acid C1 Br H acyl amino acid C1 Br NH2 acyl amino acid C1 Br NH-cyclopropyl acyl amino acid C1 Br NH-methyl acyl amino acid Cl Br NH-ethyl acyl amino acid C1 Br NH-acetyl acyl amino acid C1 Br OH acyl amino acid C1 Br OMe acyl amino acid C1 Br OEt acyl amino acid C1 Br 0-cyclopropyl acyl amino acid C1 Br O-acetyl acyl amino acid C1 Br SH acyl amino acid C1 Br SMe acyl amino acid C1 Br SEt acyl amino acid C1 Br S-cyclopropyl acyl amino acid C1 Br F acyl amino acid C1 Br Cl acyl amino acid C1 Br Br acyl amino acid C1 Br I H acyl C1 Br H H acyl C1 Br NH2 H acyl C1 Br NH-cyclopropyl H acyl C1 Br NH-methyl H acyl C1 Br NH-ethyl H acyl C1 Br NH-acetyl H acyl C1 Br OH H acyl C1 Br OMe H acyl C1 Br OEt H acyl C1 Br O-cyclopropyl H acyl Cl Br 0-acetyl R R3 Xl x2 H acyl C1 Br SH H acyl C1 Br SMe H acyl C1 Br SEt H acyl Cl Br S-cyclopropyl H acyl C1 Br F H acyl C1 Br C1 H acyl C1 Br Br H acyl C1 Br H amino acid Cl Br H H amino acid C1 Br NH2 H amino acid Cl Br NH-cyclopropyl H amino acid Cl Br NH-methyl H amino acid Cl Br NH-ethyl H amino acid C1 Br NH-acetyl H amino acid CI Br OH H amino acid C1 Br OMe H amino acid C1 Br OEt H amino acid Cl Br 0-cyclopropyl H amino acid C1 Br 0-acetyl H amino acid CI Br SH H amino acid C1 Br SMe H amino acid C1 Br SEt H amino acid Cl Br S-cyclopropyl H amino acid Cl Br F H amino acid Cl Br CI H amino acid C1 Br Br H amino acid C1 Br I amino acid amino acid Cl Br H amino acid amino acid Cl Br NH2 amino acid amino acid Cl Br NH-cyclopropyl amino acid amino acid Cl Br NH-methyl amino acid amino acid Cl Br NH-ethyl amino acid amino acid Cl Br NH-acetyl amino acid amino acid Cl Br OH amino acid amino acid Cl Br OMe amino acid amino acid CI Br OEt amino acid amino acid C1 Br 0-cyclopropyl amino acid amino acid Cl Br 0-acetyl amino acid amino acid Cl Br SH amino acid amino acid Cl Br SMe amino acid amino acid Cl Br SEt amino acid amino acid C1 Br S-cyclopropyl amino acid amino acid Cl Br F amino acid amino acid Cl Br Cl amino acid amino acid C1 Br Br amino acid amino acid C1 Br I amino acid H Cl Br H R R X X Y amino acid H Cl Br NH2 amino acid H Cl Br NH-cyclopropyl amino acid H Cl Br NH-methyl amino acid H C1 Br NH-ethyl amino acid H Cl Br NH-acetyl amino acid H Cl Br OH amino acid H Cl Br OMe amino acid H Cl Br OEt amino acid H 0-cyclopropyl amino acid H Cl Br 0-acetyl amino acid H Cl Br SH amino acid H C1 Br SMe amino acid H Cl Br SEt amino acid H Cl Br S-cyclopropyl amino acid H Cl Br F amino acid H Cl Br Cl amino acid H Cl Br Br amino acid H Cl Br I amino acid acyl C1 Br H amino acid acyl C1 Br NH2 amino acid acyl Cl Br NH-cyclopropyl amino acid acyl C1 Br NH-methyl amino acid acyl C1 Br NH-ethyl amino acid acyl C1 Br NH-acetyl amino acid acyl C1 Br OH amino acid acyl C1 Br OMe amino acid acyl C1 Br OEt amino acid ac 1 Cl Br O-c clopro yl amino acid acyl C1 Br 0-acetyl amino acid acyl C1 Br SH amino acid acyl C1 Br SMe amino acid acyl C1 Br SEt amino acid acyl C1 Br S-cyclopropyl amino acid acyl C1 Br F amino acid acyl C1 Br Cl amino acid acyl C1 Br Br amino acid acyl ci Br I acyl H Br C1 H acyl H Br C1 NH2 acyl H Br Cl NH-cyclopropyl acyl H Br C1 NH-methyl acyl H Br C1 NH-ethyl acyl H Br C1 NH-acetyl acyl H Br C1 OH acyl H Br C1 OMe acyl H Br C1 OEt acyl H Br Cl O-cyclopropyl R2 R3 Xl x2 acyl H Br C1 O-acetyl acyl H Br C1 SH acyl H Br C1 SMe acyl H Br C1 SEt ac 1 H Br CI S-c clo ro 1 acyl H Br Cl F acyl H Br C1 C1 acyl H Br C1 Br acyl H Br Cl I acyl acyl Br C1 H acyl acyl Br C1 NH2 acyl ac 1 Br Cl NH-cyclopropyl ac 1 ac 1 Br Cl NH-meth 1 ac 1 ac 1 Br Cl NH-eth 1 acyl acyl Br C1 NH-acetyl acyl acyl Br C1 OH acyl acyl Br C1 OMe acyl acyl Br C1 OEt ac 1 acyl Br CI O-c clo ro 1 acyl acyl Br C1 O-acetyl acyl acyl Br C1 SH acyl acyl Br C1 SMe acyl acyl Br C1 SEt ac 1 ac 1 Br Cl S-c clo ro 1 acyl acyl Br C1 F acyl acyl Br Cl Cl acyl acyl Br C1 Br acyl acyl Br C1 I acyl amino acid Br C1 H acyl amino acid Br C1 NH2 acyl amino acid Br Cl NH-cyclopropyl acyl amino acid Br C1 NH-methyl acyl amino acid Br Cl NH-ethyl # acyl amino acid Br C1 NH-acetyl acyl amino acid Br Cl OH acyl amino acid Br Cl OMe acyl amino acid Br C1 OEt ac 1 amino acid Br Cl O-c clo ro 1 acyl amino acid Br C1 O-acetyl acyl amino acid Br Cl SH acyl amino acid Br Cl SMe acyl amino acid Br C1 SEt ac 1 amino acid Br CI S-c clo ro 1 acyl amino acid Br C1 F acyl amino acid Br C1 C1 acyl amino acid Br ci Br acyl amino acid Br Cl I R2 R3 Xl X2 H acyl Br C1 H H acyl Br C1 NH2 H acyl Br Cl NH-cyclopropyl H acyl Br C1 NH-methyl H acyl Br C1 NH-ethyl H acyl Br C1 NH-acetyl H acyl Br C1 OH H acyl Br C1 OMe H acyl Br C1 OEt H acyl Br Cl O-cyclopropyl H _ acyl Br C1 O-acetyl H acyl Br C1 SH H acyl Br C1 SMe H acyl Br C1 SEt H acyl Br ci S-cyclopropyl H acyl Br C1 F H acyl Br C1 C1 H acyl Br C1 Br H acyl Br C1 H amino acid Br C1 H H amino acid Br C1 NH2 H amino acid Br Cl NH-cyclopropyl H amino acid Br C1 NH-methyl H amino acid Br Cl NH-ethyl H amino acid Br C1 NH-acetyl H amino acid Br Cl OH H amino acid Br Cl OMe H amino acid Br Cl OEt H amino acid Br Cl O-cyclopropyl H amino acid Br C1 O-acetyl H amino acid Br CI SH H amino acid Br Cl SMe H amino acid Br Cl SEt H amino acid Br Cl S-cyclopropyl H amino acid Br Cl F H amino acid Br Cl Cl H amino acid Br Cl Br H amino acid Br C1 I amino acid amino acid Br Cl H amino acid amino acid Br C1 NH2 amino acid amino acid Br Cl NH-cyclopropyl amino acid amino acid Br Cl NH-methyl amino acid amino acid Br Cl NH-ethyl amino acid amino acid Br C1 NH-acetyl amino acid amino acid Br Cl OH amino acid amino acid Br Cl OMe amino acid amino acid Br C1 OEt R R X'X Y amino acid amino acid Br Cl O-cyclopropyl amino acid amino acid Br C1 O-acetyl amino acid amino acid Br Cl SH amino acid amino acid Br Cl SMe amino acid amino acid Br Cl SEt amino acid amino acid Br Cl S-cyclopropyl amino acid amino acid Br Cl F amino acid amino acid Br Cl Cl amino acid amino acid Br Cl Br amino acid amino acid Br Cl I amino acid H Br Cl H amino acid H Br C1 NH2 amino acid H Br Cl NH-cyclopropyl amino acidHBr Cl NH-methyl amino acid H Br Cl NH-ethyl amino acid H Br C1 NH-acetyl amino acid H Br Cl OH amino acid H Br Cl OMe amino acid H Br Cl OEt amino acid H Br Cl O-cyclopropyl amino acid H Br Cl O-acetyl amino acid H Br Cl SH amino acid H Br Cl SMe amino acid H Br Cl SEt amino acid H Br Cl S-cyclopropyl amino acid H Br Cl F amino acid H Br Cl Cl amino acid H Br Cl Br amino acid H Br Cl I amino acid acyl Br C1 H amino acid acyl Br C1 NH2 amino acid acyl Br Cl NH-cyclopropyl amino acid acyl Br C1 NH-methyl amino acid acyl Br Cl NH-ethyl amino acid acyl Br C1 NH-acetyl amino acid acyl Br C1 OH amino acid acyl Br Cl OMe amino acid acyl Br C1 OEt amino acid Cl 0-cyclopropyl amino acid acyl Br C1 O-acetyl amino acid acyl Br C1 SH amino acid acyl Br C1 SMe amino acid acyl Br C1 SEt amino acid ac 1 Br Cl S-c clo ro 1 amino acid acyl Br C1 F amino acid acyl Br C1 C1 amino acid acyl Br C1 Br R R X'X Y amino acid acyl Br C1 I acyl H H C1 H acyl H H C1 NH2 acyl H H C1 NH-cyclopropyl acyl H H C1 NH-methyl acyl H H C1 NH-ethyl acyl H H C1 NH-acetyl acyl H H C1 OH acyl H H C1 OMe acyl H H C1 OEt acyl H H Cl O-cyclopropyl acyl H H C1 O-acetyl acyl H H C1 SH acyl H H C1 SMe acyl H H C1 SEt acyl H H C1 S-cyclopropyl acyl H H C1 F acyl H H C1 C1 acyl H H C1 Br acyl H H C1 acyl acyl H C1 H acyl acyl H C1 NH2 acyl acyl H C1 NH-cyclopropyl acyl acyl H C1 NH-methyl acyl acyl H C1 NH-ethyl acyl acyl H C1 NH-acetyl acyl acyl H C1 OH acyl acyl H C1 OMe acyl acyl H C1 OEt acyl acyl H Cl O-cyclopropyl acyl acyl H C1 O-acetyl acyl acyl H C1 SH acyl acyl H C1 SMe acyl acyl H C1 SEt acyl acyl H C1 S-cyclopropy acyl acyl H C1 F acyl acyl H C1 Cl acyl acyl H C1 Br acyl acyl H C1 I acyl amino acid H Cl H acyl amino acid H C1 NH2 acyl amino acid H Cl NH-cyclopropyl acyl amino acid H C1 NH-methyl acyl amino acid H C1 NH-ethyl acyl amino acid H C1 NH-acetyl acyl amino acid H C1 OH acyl amino acid H Cl OMe R R X X Y acyl amino acid H Cl OEt acyl amino acid H Cl O-cyclopropyl acyl amino acid H Cl O-acetyl acyl amino acid H Cl SH acyl amino acid H Cl SMe acyl amino acid H Cl SEt acyl amino acid H Cl S-cyclopropyl acyl amino acid H Cl F acyl amino acid H Cl Cl acyl amino acid H Cl Br acyl amino acid H C1 H acyl H C1 H H acyl H C1 NH2 H acyl H Cl NH-cyclopropyl H acyl H C1 NH-methyl H acyl H C1 NH-ethyl H acyl H C1 NH-acetyl H acyl H C1 OH H acyl H C1 OMe H acyl H C1 OEt H acyl H Cl O-cyclopropyl H acyl H Cl O-acetyl H acyl H C1 SH H acyl H C1 SMe H acyl H C1 SEt H acyl H I Cl S-cyclopropyl H acyl H C1 F H acyl H C1 C1 H acyl H C1 Br H acyl H C1 I H amino acid H Cl H H amino acid H C1 NH2 H amino acid H Cl NH-cyclopro l H amino acid H C1 NH-methyl H amino acid H Cl NH-ethyl # H amino acid H C1 NH-acetyl H amino acid H C1 OH H amino acid H Cl OMe H amino acid H Cl OEt H amino acid H Cl O-cyclopropyl H amino acid H Cl O-acetyl H amino acid H Cl SH H amino acid H Cl SMe H amino acid H Cl SEt H amino acid H Cl S-cyclopropyl H amino acid H C1 F H _ amino acid H C1 C1 R R3 Xl x2 H amino acid H Cl Br H amino acid H Cl I amino acid amino acid H Cl H amino acid amino acid H C1 NH2 amino acid amino acid H C1 NH-cyclopropyl amino acid amino acid H Cl NH-methyl amino acid amino acid H_ C1 NH-ethyl amino acid amino acid H C1 NH-acetyl amino acid amino acid H Cl OH amino acid amino acid H Cl OMe amino acid amino acid C1 OEt amino acid amino acid H Cl O-cyclo ropyl yc p PY amino acid amino acid H C1 O-acetyl amino acid amino acid H Cl SH amino acid amino acid H Cl SMe amino acid amino acid H Cl SEt amino acid amino acid H C1 S-cyclopropyl amino acid amino acid H Cl F amino acid amino acid H Cl Cl amino acid amino acid H Cl Br amino acid amino acid H Cl I amino acid H H C1 H amino acid H H C1 NH2 amino acid H H C1 NH-cyclopropyl amino acid H H C1 NH-methyl amino acid H H C1 NH-ethyl amino acid H H C1 NH-acetyl amino acid H H ci OH amino acid H H Cl OMe amino acid H H Cl OEt amino acid H 0-cyclopropyl amino acid H H C1 O-acetyl amino acid H H Cl SH amino acid H H Cl SMe amino acid H H C1 SEt amino acid H H C1 S-cyclopropyl amino acid H H Cl F amino acid H H Cl Cl amino acid H H Cl Br amino acid H H Cl I amino acid acyl H Cl H amino acid acyl H C1 NH2 amino acid ac 1 H Cl NH-cyclopropyl amino acid acyl H C1 NH-methyl amino acid acyl H C1 NH-ethyl amino acid acyl H C1 NH-acetyl amino acid acyl H C1 OH R R X X Y amino acid acyl H C1 OMe amino acid acyl H C1 OEt amino acid ac 1 H Cl O-cyclo ro yl amino acid acyl H C1 O-acetyl amino acid acyl H C1 SH amino acid acyl H C1 SMe amino acid acyl H C1 SEt amino acid ac 1 H Cl S-c clo ro 1 amino acid acyl H Cl F amino acid acyl H C1 C1 amino acid acyl H C1 Br amino acid acyl H C1 I acyl H C1 H H acyl H Cl H NH2 acyl H Cl H NH-cyclo ro yl ac 1 H Cl H NH-meth 1 acyl H C1 H NH-ethyl acyl H C1 H NH-acetyl acyl H C1 H OH acyl H C1 H OMe acyl H C1 H OEt acyl H Cl H O-cyclopropyl ac 1 H C1 H O-acet 1 acyl H C1 H SH acyl H C1 H SMe acyl H C1 H SEt acyl H Cl H S-cyclopropyl acyl H ci H F acyl H C1 H C1 acyl H Cl H Br acyl H C1 H acyiHC1JHj [ acyl acyl C1 H H acyl acyl C1 H NH2 acyl acyl C1 H NH-cyclopropyl acyl acyl Cl H NH-methyl acyl acyl C1 H NH-ethyl acyl acyl C1 H NH-acetyl acyl acyl C1 H OH acyl acyl C1 H OMe acyl acyl C1 H OEt acyl acyl C1 H 0-cyclopropyl acyl acyl C1 H 0-acetyl acyl acyl C1 H SH acyl acyl C1 H SMe acyl acyl C1 H SEt acyl acyl Cl H S-cyclopropyl acyl acyl C1 H F R R X'X Y acyl acyl C1 H C1 acyl acyl C1 H Br acyl acyl Cl H I acyl amino acid C1 H H acyl amino acid Cl H NHz acyl amino acid C1 H NH-cyclopropyl ac 1 amino acid Cl H NH-methyl acyl amino acid C1 H NH-ethyl acyl amino acid Cl H NH-acetyl acyl amino acid C1 H OH acyl amino acid C1 H OMe acyl amino acid C1 H OEt acyl amino acid Cl H O-cyclo ro 1 acyl amino acid C1 H O-acetyl acyl amino acid Cl H SH acyl amino acid C1 H SMe acyl amino acid C1 H SEt acyl amino acid C1 H S-cyclopropyl acyl amino acid C1 H F acyl amino acid Cl H Cl acyl amino acid C1 H Br acyl amino acid C1 H I H acyl C1 H H acyl C1 H NH2 H acyl C1 H NH-cyclopropyl H acyl C1 H NH-methyl H acyl C1 H NH-ethyl H acyl C1 H NH-acetyl H acyl C1 H OH H acyl C1 H OMe H acyl C1 H OEt H acyl Cl H 0-cyclopropyl H acyl Cl H O-acetyl H acyl C1 H SH H acyl C1 H SMe H acyl C1 H SEt H ac 1 Cl H S-c clo ro 1 JHacyiJdJHJF JHacyiJdJHJd HacyiJdJHJ8r H acyl C1 H F H acyl C1 H ci H acyl C1 H Br H acyl ci H I H amino acid Cl H H H amino acid Cl H NH2 H amino acid Cl H NH-cyclopropyl H amino acid C1 H NH-methyl H amino acid C1 H NH-ethyl H amino acid Cl H NH-acetyl R R X X Y H amino acid Cl H OH H amino acid C1 H OMe H amino acid CI H OEt H amino acid Cl H 0-cyclopropyl H amino acid Cl H 0-acetyl H amino acid Cl H SH H amino acid Cl H SMe H amino acid Cl H SEt H amino acid Cl H S-cyclope H amino acid C1 H H amino acid C1 H C1 H amino acid Cl H Br H amino acid C1 H I amino acid amino acid Cl H H amino acid amino acid C1 H NH2 amino acid amino acid Cl H NH-cyclopropyl amino acid amino acid Cl H NH-methyl amino acid amino acid Cl H NH-ethyl amino acid amino acid C1 H NH-acetyl amino acid amino acid Cl H OH amino acid amino acid Cl H OMe amino acid amino acid Cl H OEt amino acidamino acidCl H0-cyclopropyl amino acid amino acid Cl H 0-acetyl amino acid amino acid Cl H SH amino acid amino acid Cl H SMe amino acid amino acid Cl H SEt amino acid amino acid Cl H S-cyclopropyl amino acid amino acid Cl H F amino acid amino acid Cl H Cl amino acid amino acid Cl H Br amino acid amino acid Cl H I amino acid H Cl H H amino acid C1 H NH2 amino acid H Cl H NH-cyclopropyl amino acid H C1 H NH-methyl amino acid H C1 H NH-ethyl amino acid H Cl H Nu-acetyl amino acid H Cl H OH amino acid H Cl H OMe amino acid H Cl H OEt amino acid H 0-cyclopropyl amino acid H Cl H 0-acetyl amino acid H Cl H SH amino acid H Cl H SMe amino acid H C1 H SEt amino acid H C1 H S-cyclopropyl R R X X Y amino acid H Cl H F amino acid H C1 H C1 amino acid H Cl H Br amino acid H Cl H I amino acid acyl C1 H amino acid acyl Cl H NHz amino acid acyl C1 H NH-cyclopropyl amino acid acyl C1 H NH-methyl amino acid acyl Cl H NH-ethyl amino acid acyl C1 H NH-acetyl amino acid acyl C1 H OH amino acid acyl C1 H OMe amino acid acyl Cl H OEt amino acid acyl Cl H 0-cyclopropyl amino acid acyl Cl H 0-acetyl amino acid acyl C1 H SH amino acid acyl C1 H SMe amino acid acyl C1 H SEt amino acid acyl Cl H S-cyclopropyl amino acid acyl Cl H F amino acid acyl C1 H ci amino acid acyl ci H Br amino acid acyl C1 H I ; 7 acyl H C1 NH2 H acyl H C1 NH2 NH2 acyl H Cl NHz NH-cyclopropyl acyl H C1 NH2 NH-methyl acyl H C1 NH2 NH-ethyl acyl H C1 NH2 NH-acetyl acyl H C1 NH2 OH acyl H C1 NH2 OMe acyl H C1 NH2 OEt acyl H Cl NH2 O-cyclopropyl acyl H C1 NH2 O-acetyl acyl H C1 NH2 SH acyl H Cl NH2 SMe acyl H C1 NH2 SEt acyl H Cl NH2 S-cyclopropyl acyl H C1 NH2 F acyl H ci NH2 ci acyl H C1 NH2 Br acyl H C1 NH2 acyl acyl C1 NH2 H acyl acyl C1 NH2 NH2 acyl acyl Cl NH2 NH-cyclopropyl acyl acyl C1 NH2 NH-methyl acyl acyl C1 NH2 NH-ethyl R R X X Y acyl acyl C1 NH2 NH-acetyl acyl acyl C1 NH2 OH acyl acyl 0 C1 NH2 OMe acyiacyiClNH2 OEt acyl acyl Cl NH2 O-cyclopropyl acyl acyl C1 NH2 O-acetyl acyl acyl C1 NH2 SH acyl acyl C1 NH2 SMe acyl acyl C1 NH2 SEt acyl acyl_ C1 NH2 S-cyclopropyl acyl acyl C1 NH2 F acyl acyl C1 NH2 C1 acyl acyl C1 NH2 Br acyl acyl C1 0 NH2 acyl amino acid Cl NH2 H acyl _ amino acid C1 NH2 NH2 acyl amino acid Cl NH2 NH-cyclopropyl acyl amino acid C1 NH2 NH-methyl acyl amino acid C1 NH2 NH-ethyl D amino acid C1 NH2 NH-acetyl acyl amino acid C1 NH2 OH acyl amino acid C1 NH2 OMe acyl amino acid C1 NH2 OEt acyl amino acid Cl NH2 O-cyclopropyl acyl amino acid C1 NH2 O-acetyl acyl amino acid Cl NH2 SH acyl amino acid C1 NH2 SMe acyl amino acid Cl NH2 SEt acyl amino acid Cl NH2 S-cyclopropyl acyl amino acid C1 NH2 F acyl amino acid C1 NH2 C1 acyl amino acid C1 NH2 Br acyl amino acid C1 NH2 I H acyl C1 NH2 H H acyl C1 NH2 NH2 H ac 1 Cl NHZ NH-c clo ro 1 H acyl C1 NH2 NH-methyl H acyl C1 NH2 NH-ethyl H acyl C1 NH2 _ NH-acetyl H acyl C1 NH2 OH H acyl C1 NH2 OMe H acyl C1 NH2 OEt H acyl Cl NH2 O-cyclopropyl H acyl C1 NH2 O-acetyl H acyl C1 NH2 SH H acyl C1 NH2 SMe H acyl C1 NH2 SEt R R X X Y H ac 1 CI NHz S-c clo ro I H ac 1 Cl NHz F H acyl C1 NH2 C1 H acyl C1 NH2 Br H acyl C1 NH2 H amino acid Cl NH2 H H amino acid CI NH2 NH2 H amino acid Cl NH2 NH-cyclopropyl H amino acid C1 NH2 NH-methyl H amino acid C1 NH2 NH-ethyl H amino acid Cl NH2 NH-acetyl H amino acid Cl NH2 OH H amino acid C1 NH2 OMe H amino acid Cl NH2 OEt H amino acid Cl NH2 O-cyclopropyl H amino acid Cl NH2 O-acetyl H amino acid C1 NH2 SH ~- H amino acid C1 NH2 SMe H amino acid Cl NH2 SEt H amino acid Cl NHz S-cyclo ro 1 H amino acid C1 NH2 Haminoacid Cl NH2 Cl Hamino acidCl NH2 Br Hamino acidCl NH2 I amino acid amino acid C1 NH2 H amino acid amino acid Cl NH2 NH2 amino acid amino acid CI NH2 NH-cycloprop1 amino acid amino acid Cl NH2 NH-methyl amino acid amino acid C1 NH2 NH-ethyl amino acid amino acid C1 NH2 NH-acetyl amino acid amino acid C1 NH2 OH amino acid amino acid C1 NH2 OMe amino acid amino acid C1 NH2 OEt amino acid amino acid Cl NH2 O-cyclopropyl amino acid amino acid C1 NH2 O-acetyl amino acid amino acid C1 NH2 SH amino acid amino acid Cl NH2 SMe amino acid amino acid C1 NH2 ~ SEt amino acid amino acid Cl NH2 S-cyclopropyl amino acid amino acid C1 NH2 F amino acid amino acid C1 NH2 C1 amino acid amino acid C1 NH2 Br amino acid amino acid C1 NH2 I amino acid H C1 NH2 amino acid H ci NH2 NH2 amino acid H CI NHz NH-c clo ro 1 amino acid H Cl NH2 NH-methyl R2 R3-Xl x2 amino acid H C1 NH2 NH-ethyl amino acid H C1 NH2 NH-acetyl amino acid H Cl NHz OH amino acid H Cl NH2 OMe amino acid H C1 NH2 OEt amino acid H Cl NH2 O-cyclopropyl amino acid H C1 NH2 O-acetyl aAnino acid H C1 NH2 SH amino acid H Cl NH2 SMe aminoacid HC1NH2 SEt amino acid H Cl NH2 S-cyclopropyl amino acid H C1 NH2 F amino acid H C1 NH2 C1 amino acid H C1 NH2 Br amino acid H C1 NH2 I amino acid acyl C1 NH2 H amino acid acyl C1 NH2 NH2 amino acid acyl Cl NH2 NH-cyclopropyl amino acid acyl C1 NH2 NH-methyl amino acid acyl C1 NH2 NH-ethyl amino acid acyl C1 NH2 NH-acetyl amino acid acyl Cl NH2 OH amino acid acyl C1 NH2 OMe amino acid acyl C1 NH2 OEt amino acid acyl C1 NH2 O-cyclopropyl amino acid acyl C1 NH2 O-acetyl amino acid acyl C1 NH2 SH amino acid acyl C1 NH2 SMe amino acid acyl C1 NH2 SEt amino acid ac 1 Cl NHZ S-c clo ro 1 amino acid acyl C1 NH2 F amino acid acyl C1 NH2 C1 amino acid acyl C1 NH2 Br amino acid acyl C1 NH2 I acyl H SH NH2 H acyl H SH NH2 NH2 acyl H SH NH2 NH-cyclopropyl acyl H SH NH2 NH-methyl acyl H SH NH2 NH-ethyl acyl H SH NH2 NH-acetyl acyl H SH NH2 OH acyl H SH NH2 OMe acyl H SH NH2 OEt acyl H SH NH2 0-cyclopropyl acyl H SH NH2 O-acetyl acyl H SH NH2 SH acyl H SH NH2 SMe R R3 Xl X2 | Y acyl SH NH2 SEt acyl H SH NH2 S-cyclopropyl acyl H SH NH2 F ac 1 H SH NHz Cl acyl H SH NH2 Br acyl H SH NH2 I acyl acyl SH NH2 H acyl acyl SH NH2 NH2 acyl acyl SH NH2 NH-cyclopropyl acyl acyl SH NH2 NH-methyl acyl acyl SH NH2 NH-ethyl acyl acyl SH NH2 NH-acetyl acyl acyl SH NH2 OH acyl acyl SH NH2 OMe acyl acyl SH NH2 OEt acyl acyl SH NH2 O-cyclopropyl acyl acyl SH NH2 O-acetyl acyl acyl SH NH2 SH acyl acyl SH NH2 SMe acyl acyl SH NH2 SEt acyl acyl SH NH2 S-cyclopropyl acyl acyl SH NH2 F acyl acyl SH NH2 C1 acyl acyl SH NH2 Br acyl acyl SH NH2 I acyl amino acid SH NH2 H acyl amino acid SH NH2 NH2 acyl amino acid SH NH2 NH-cyclopropyl acyl amino acid SH NH2 NH-methyl acyl amino acid SH NH2 NH-ethyl acyl amino acid SH NH2 NH-acetyl acyl amino acid SH NH2 OH acyl amino acid SH NH2 OMe acyl amino acid SH NH2 OEt acyl amino acid SH NH2 O-cyclopropyl acyl amino acid SH NH2 O-acetyl acyl amino acid SH NH2 SH acyl amino acid SH NH2 SMe acyl amino acid SH NHz SEt acyl amino acid SH NH2 S-cyclopropyl acyl amino acid SH NH2 F acyl amino acid SH NH2 C1 acyl amino acid SH NH2 Br acyl amino acid SH NH2 I H acyl SH NH2 H H acyl SH NH2 NH2 H acyl SH NH2 NH-cyclopropyl R R'X X Y H acyl SH NH2 NH-methyl H acyl SH NH2 NH-ethyl H acyl SH NH2 NH-acetyl H acyl SH NH2 OH H acyl SH NH2 OMe H acyl SH NH2 OEt H acyl SH NH2 O-cyclopropyl H acyl SH NH2 O-acetyl H acyl SH NH2 SH H acyl SH NH2 SMe H acyl SH NH2 SEt H acyl SH NH2 S-cyclopropyl H acyl SH NH2 F H acyl SH NH2 C1 H acyl SH NH2 Br H acyl SH NH2 I H amino acid SH NH2 H H amino acid SH NH2 NH2 H amino acid SH NH2 NH-cyclopropyl H amino acid SH NH2 NH-methyl H amino acid SH NH2 NH-ethyl H amino acid SH NH2 NH-acetyl H amino acid SH NH2 OH H amino acid SH NH2 OMe H amino acid SH NH2 OEt H amino acid SH NH2 0-cyclopropyl H amino acid SH NH2 O-acetyl H amino acid SH NH2 SH H amino acid SH NH2 SMe H amino acid SH NH2 SEt H amino acid SH NH2 S-cyclopropyl H amino acid SH NH2 F H amino acid SH NH2 Cl H amino acid SH NH2 Br H amino acid SH NH2 I amino acid amino acid SH NH2 H amino acid amino acid SH NH2 NH2 amino acid amino acid SH NH2 NH-cyclopropyl amino acid amino acid SH NH2 NH-methyl amino acid amino acid SH NH2 NH-ethyl amino acid amino acid SH NH2 NH-acetyl amino acid amino acid SH NH2 OH amino acid amino acid SH NH2 OMe amino acid amino acid SH NH2 OEt amino acid amino acid SH NH2 0-cyclopropyl # amino acid amino acid SH NH2 0-acetyl amino acid amino acid SH NH2 SH R2 R3 Xl X2 | Y amino acid amino acid SH NH2 SMe amino acid amino acid SH NH2 SEt amino acid amino acid SH NH2 S-cyclopropyl amino acid amino acid SH NH2 F amino acid amino acid SH NH2 Cl amino acid amino acid SH NH2 Br amino acid amino acid SH NH2 I amino acid H SH NH2 H amino acid H SH NH2 NH2 amino acid H SH NH2 NH-cyclopropyl amino acid H SH NH2 NH-methyl amino acid H SH NH2 NH-ethyl amino acid H SH NH2 NH-acetyl amino acid H SH NH2 OH amino acid H SH NH2 OMe amino acid H SH NH2 OEt amino acid H SH NH2 O-cyclopropyl amino acid H SH NH2 0-acetyl amino acid H SH NH2 SH amino acid H SH NH2 SMe amino acid H SH NH2 SEt amino acid H SH NH2 S-cyclopropyl amino acid H SH NH2 F amino acid H SH NH2 Cl amino acid H SH NH2 Br amino acid H SH NH2 I amino acid acyl SH NH2 H amino acid acyl SH NH2 NH2 amino acid ac 1 SH NHZ NH-c clo ro 1 amino acid acyl SH NH2 NH-methyl amino acid acyl SH NH2 NH-ethyl amino acid acyl SH NH2 NH-acetyl amino acid acyl SH NH2 OH amino acid acyl SH NH2 OMe amino acid acyl SH NH2 OEt amino acid acel SH NH2 O-cvolopropyl r, A AJ amino acid acyl SH NH2 0-acetyl amino acid acyl SH NH2 SH amino acid acyl SH NH2 SMe amino acid acyl SH NH2 SEt amino acid acyl SH NH2 S-cyclopropyl amino acid acyl SH NH2 F amino acid acyl SH NH2 C1 amino acid acyl SH NH2 Br amino acid acyl SH NH2 I acyl H Br NH2 H acyl H Br NH2 NH2 R2 R3 Xl X2 Y acyl H Br NH2 NH-cyclopropyl acyl H Br NH2 NH-methyl acyl H Br NH2 NH-ethyl acyl H Br NH2 NH-acetyl acyl H Br NH2 OH acyl H Br NH2 OMe acyl H Br NH2 OEt acyl H Br NH2 O-cyclopropyl acyl H Br NH2 0-acetyl acyl H Br NH2 SH acyl H Br NH2 SMe acyl H Br NH2 SEt acyl H Br NH2 S-cyclopropyl acyl H Br NH2 F acyl H Br NH2 Cl acyl H Br NH2 Br acyl H Br NH2 acyl acyl Br NH2 H acyl acyl Br NH2 NH2 acyl acyl Br NH2 NH-cyclopropyl acyl acyl Br NH2 NH-methyl acyl acyl Br NH2 NH-ethyl acyl acyl Br NH2 NH-acetyl acyl acyl Br NH2 OH acyl acyl Br NH2 OMe acyl acyl Br NH2 OEt acyl acyl Br NH2 O-cyclopropyl acyl acyl Br NH2 O-acetyl acyl acyl Br NH2 SH acyl acyl Br NH2 SMe acyl acyl Br NH2 SEt acyl acyl Br NH2 S-cyclopropyl acyl acyl Br NH2 F acyl acyl Br NH2 Cl acyl acyl Br NH2 Br acyl acyl Br NH2 I acyl amino acid Br NH2 H acyl amino acid Br NH2 NH2 acyl amino acid Br NH2 NH-cyclopropyl acyl amino acid Br NH2 NH-methyl acyl amino acid Br NH2 NH-ethyl acyl amino acid Br NH2 NH-acetyl acyl amino acid Br NH2 OH acyl amino acid Br NH2 OMe acyl amino acid Br NH2 OEt acyl amino acid Br NH2 O-cyclopropyl acyl amino acid Br NH2 0-acetyl R R X X Y acyl amino acid Br NH2 SH acyl amino acid Br NH2 SMe acyl amino acid Br NH2 SEt acyl amino acid Br NH2 S-cyclopropyl acyl amino acid Br NH2 F acyl amino acid Br NH2 C1 acyl amino acid Br NH2 Br acyl amino acid Br NH2 I H acyl Br NH2 H H acyl Br NH2 NH2 H acyl Br NH2 NH-cyclopropyl H acyl Br NH2 NH-methyl H acyl Br NH2 NH-ethyl H acyl Br NH2 NH-acetyl H acyl Br NH2 OH H acyl Br NH2 OMe H acyl Br NH2 OEt H acyl Br NH2 O-cyclopropyl H acyl Br NH2 O-acetyl H acyl Br NH2 SH H acyl Br NH2 SMe H acyl Br NH2 SEt H acyl Br NH2 S-cyclopropyl H acyl Br NH2 F H acyl Br NH2 C1 H acyl Br NH2 Br H acyl Br NH2 I H amino acid Br NH2 H H amino acid Br NH2 NH2 H amino acid Br NH2 NH-cyclopropyl H amino acid Br NH2 NH-methyl H amino acid Br NH2 NH-ethyl H amino acid Br NH2 NH-acetyl H amino acid Br NH2 OH H amino acid Br NH2 OMe H amino acid Br NH2 OEt H amino acid Br NH2 0-cyclopropyl H amino acid Br NH2 0-acetyl H amino acid Br NH2 SH H amino acid Br NH2 SMe H amino acid Br NH2 SEt H amino acid Br NH2 S-cyclopropyl H amino acid Br NH2 F H amino acid Br NH2 C1 H amino acid Br NH2 Br H amino acid Br NH2 I amino acid amino acid Br NH2 H Ri R3 Xl x2 amino acid amino acid Br NH2 NH2 amino acid amino acid Br NH2 NH-cyclopropyl amino acid amino acid Br NH2 NH-methyl amino acid amino acid Br NH2 NH-ethyl amino acid amino acid Br NH2 NH-acetyl amino acid amino acid Br NH2 OH amino acid amino acid Br NH2 OMe amino acid amino acid Br NH2 OEt amino acid amino acid Br NH2 0-cyclopropyl amino acid amino acid Br NH2 0-acetyl amino acid amino acid Br NH2 SH amino acid amino acid Br NH2 SMe amino acid amino acid Br NH2 SEt amino acid amino acid Br NH2 S-cyclopropyl amino acid amino acid Br NH2 F amino acid amino acid Br NH2 C1 amino acid amino acid Br NH2 Br amino acid amino acid Br NH2 I amino acid H Br NH2 H amino acid H Br NH2 NH2 amino acid H Br NH2 NH-cyclopropyl amino acid H Br NH2 NH-methyl amino acid H Br NH2 NH-ethyl amino acid H Br NH2 NH-acetyl amino acid H Br NH2 OH amino acid H Br NH2 OMe amino acid H Br NH2 OEt amino acid H Br NH2 O-cyclopropyl amino acid H Br NH2 O-acetyl amino acid H Br NH2 SH amino acid H Br NH2 SMe amino acid H Br NH2 SEt amino acid H Br NH2 S-cyclopropyl amino acid H Br NH2 F amino acid H Br NH2 C1 amino acid H Br NH2 Br amino acid H Br NH2 I amino acid acyl Br NH2 H amino acid acyl Br NH2 NH2 amino acid acyl Br NH2 NH-cyclopropyl amino acid acyl Br NH2 NH-methyl amino acid acyl Br NH2 NH-ethyl amino acid acyl Br NH2 NH-acetyl amino acid acyl Br NH2 OH amino acid acyl Br NH2 OMe amino acid acyl Br NH2 OEt amino acid acyl Br NH2 O-cyclopropyl R R X X Y amino acid acyl Br NH2 0-acetyl amino acid acyl Br NH2 SH amino acid acyl Br NH2 SMe amino acid acyl Br NH2 SEt amino acid acyl Br NH2 S-cyclopropyl amino acid acyl Br NH2 F amino acid acyl Br NH2 Cl amino acid acyl Br NH2 Br amino acid acyl Br NH2 I acyl H F NH2 H acyl H F NH2 NH2 acyl H F NH2 NH-cyclopropyl acyl H F NH2 NH-methyl acyl H F NH2 NH-ethyl acyl H F NH2 NH-acetyl acyl H F NH2 OH acyl H F NH2 OMe acyl H F NH2 OEt acyl H F NH2 O-cyclopropyl acyl H F NH2 O-acetyl acyl H F NH2 SH acyl H F NH2 SMe acyl H F NH2 SEt acyl H F NH2 S-cyclopropyl acyl H F NH2 F acyl H F NH2 C1 acyl H F NH2 Br acyl H F NH2 I acyl acyl F NH2 H acyl acyl F NH2 NH2 acyl acyl F NH2 NH-cyclopropyl acyl acyl F NH2 NH-methyl acyl acyl F NH2 NH-ethyl acyl acyl F NH2 NH-acetyl acyl acyl F NH2 OH acyl acyl F NH2 OMe acyl acyl F NH2 OEt acyl acyl F NH2 O-cyclopropyl acyl acyl F NH2 O-acetyl acyl acyl F NH2 SH acyl acyl F NH2 SMe acyl acyl F NH2 SEt acyl acyl F NH2 S-cyclopropyl acyl acyl F NH2 F acyl acyl F NH2 C1 acyl acyl F NH2 Br acyl acyl F NH2 R R X'X Y acyl amino acid F NH2 H acyl amino acid F NH2 NH2 acyl amino acid F NH2 NH-cyclopropyl acyl amino acid F NH2 NH-methyl acyl amino acid F NH2 NH-ethyl acyl amino acid F NH2 NH-acetyl acyl amino acid F NH2 OH acyl amino acid F NH2 OMe acyl amino acid F NH2 OEt acyl amino acid F NH2 O-cyclopropyl acyl amino acid F NH2 O-acetyl acyl amino acid F NH2 SH acyl amino acid F NH2 SMe acyl amino acid F NH2 SEt acyl amino acid F NH2 S-cyclopropyl acyl amino acid F NH2 F acyl amino acid F NH2 Cl acyl amino acid F NH2 Br acyl amino acid F NH2 I H acyl F NH2 H H acy F NH2 NH2 H acyl F NH2 NH-cyclopropyl H acyl F NH2 NH-methyl H acyl F NH2 NH-ethyl H acyl F NH2 NH-acetyl H acyl F NH2 OH H acyl F NH2 OMe H acyl F NH2 OEt H acyl F NH2 O-cyclopropyl H acyl F NH2 0-acetyl H acyl F NH2 SH H acyl F NH2 SMe H acyl F NH2 SEt H acyl F NH2 S-cyclopropyl H acyl F NH2 F H acyl F NH2 C1 H acyl F NH2 Br H acyl F NH2 I H amino acid F NH2 H H amino acid F NH2 NH2 H amino acid F NH2 NH-cyclopropyl H amino acid F NH2 NH-methyl H amino acid F NH2 NH-ethyl H amino acid F NH2 NH-acetyl H amino acid F NH2 OH H amino acid F NH2 OMe H amino acid F NH2 OEt R R X X Y H amino acid F NH2 O-cyclopropyl H amino acid F NH2 0-acetyl H amino acid F NH2 SH H amino acid F NH2 SMe H amino acid F NH2 SEt H amino acid F NH2 S-cyclopropyl H amino acid F NH2 F H amino acid F NH2 C1 H amino acid F NH2 Br H amino acid F NH2 I amino acid amino acid F NH2 H amino acid amino acid F NH2 NH2 amino acid amino acid F NH2 NH-cyclopropyl amino acid amino acid F NH2 NH-methyl amino acid amino acid F NH2 NH-ethyl amino acid amino acid F NH2 NH-acetyl amino acid amino acid F NH2 OH amino acid amino acid F NH2 OMe amino acid amino acid F NH2 OEt amino acid amino acid F NH2 O-cyclopropyl amino acid amino acid F NH2 O-acetyl amino acid amino acid F NH2 SH amino acid amino acid F NH2 SMe amino acid amino acid F NH2 SEt amino acid amino acid F NH2 S-cyclopropyl amino acid amino acid F NH2 F amino acid amino acid F NH2 C1 amino acid amino acid F NH2 Br amino acid amino acid F NH2 I amino acid H F NH2 H amino acid H F NH2 NH2 amino acid H F NH2 NH-cyclopropyl amino acid H F NH2 NH-methyl amino acid H F NH2 NH-ethyl amino acid H F NH2 NH-acetyl amino acid H F NHz OH amino acid H F NH2 OMe amino acid H F NH2 OEt amino acid H F NH2 0-yclopropyl amino acid H F NH2 O-acetyl amino acid H F NH2 SH amino acid H F NH2 SMe amino acid H F NH2 SEt amino acid H F NH2 S-cyclopropyl amino acid H F NH2 F amino acid H _ F NH2 C1 amino acid H F NH2 Br R R3 Xl XZ amino acid H F NH2 I amino acid acyl F NH2 H amino acid acyl F NH2 NH2 amino acid acyl F NH2 NH-cyclopropyl amino acid acyl F NH2 NH-methyl amino acid acyl F NH2 NH-ethyl amino acid acyl F NH2 NH-acetyl amino acid acyl F NH2 OH amino acid acyl F NH2 OMe amino acid acyl F NH2 OEt amino acid acyl F NH2 O-cyclopropyl amino acid acyl F NH2 0-acetyl amino acid acyl F NH2 SH amino acid acyl F NH2 SMe amino acid acyl F NH2 SEt amino acid acyl F NH2 S-cyclopropyl amino acid acyl F NH2 F amino acid acyl F NH2 Cl amino acid acyl F NH2 Br amino acid acyl F NH2 I acyl H NH2 F H acyl H NH2 F NH2 acyl H NH2 F NH-cyclopropyl acyl H NH2 F NH-methyl acyl H NH2 F NH-ethyl acyl H NH2 F NH-acetyl acyl H NH2 F OH acyl H NH2 F OMe acyl H NH2 F OEt acyl H NH2 F O-cyclopropyl acyl H NH2 F 0-acetyl acyl H NH2 F SH acyl H NH2 F SMe acyl H NH2 F SEt acyl H NH2 F S-cyclopropyl acyl H NH2 F F acyl H NH2 F C1 acyl H NH2 F Br acyl H NH2 F I acyl acyl NH2 F H acyl acyl NH2 F NH2 acyl acyl NH2 F NH-cyclopropyl acyl acyl NH2 F NH-methyl acyl acyl NH2 F NH-ethyl acyl acyl NH2 F NH-acetyl acyl acyl NH2 F OH acyl acyl NH2 F OMe RZ R X X Y acyl acyl NH2 F OEt acyl acyl NH2 F O-cyclopropyl acyl acyl NH2 F 0-acetyl acyl acyl NH2 F SH acyl acyl NH2 F SMe acyl acyl NH2 F SEt ac 1 ac 1 NHZ F S-c clo ro 1 acyl acyl NH2 F F acyl acyl NH2 F C1 acyl acyl NH2 F Br acyl acyl NH2 F I acyl amino acid NH2 F H acyl amino acid NH2 F NH2 acyl amino acid NH2 F NH-cyclopropyl acyl amino acid NH2 NH-methyl acyl amino acid NH2 F NH-ethyl acyl amino acid NH2 F NH-acetyl acyl amino acid NH2 F OH acyl amino acid NH2 F OMe acyl amino acid NH2 F OEt acyl amino acid NH2 F O-cyclopropyl acyl amino acid NH2 F 0-acetyl acyl amino acid NH2 F SH acyl amino acid NH2 F SMe acyl amino acid NH2 F SEt acyl amino acid NH2 F S-cyclopropyl acyl amino acid NH2 F F acyl amino acid NH2 F C1 acyl amino acid NH2 F Br acyl amino acid NH2 F I H acyl NH2 F H f H acyl NH2 F NH2 H acyl NH2 F NH-cyclopropyl H acyl NH2 F NH-methyl H acyl NH2 F NH-ethyl H acyl NH2 F NH-acetyl H acyl NH2 F OH H acyl NH2 F OMe H acyl NH2 F OEt H acyl NH2 F 0-cyclopropyl H acyl NH2 F 0-acetyl H acyl NH2 F SH H acyl NH2 F SMe H acyl NH2 F SEt H acyl NH2 F S-cyclopropyl H acyl NH2 F F H acyl NH2 F C1 R R X'X Y H acyl NH2 F Br H acyl NH2 F I H amino acid NH2 F H H amino acid NH2 F NH2 H amino acid NH2 F NH-cyclopropyl H amino acid NH2 F NH-methyl H amino acid NH2 F NH-ethyl H amino acid NH2 F NH-acetyl H amino acid NH2 F OH H amino acid NH2 F OMe H amino acid NH2 F OEt H amino acid F0-cyclopropyl H amino acid NH2 F O-acetyl H amino acid NH2 F SH H amino acid NH2 F SMe H amino acid NH2 F SEt H amino acid NH2 F S-cyclopropyl H amino acid NH2 F F H amino acid NH2 F C1 H amino acid NH2 F Br H amino acid NH2 F I amino acid amino acid NH2 F H amino acid amino acid NH2 F NH2 amino acid amino acid NH2 F NH-cyclopropyl amino acid amino acid. NH2 F NH-methyl amino acid amino acid NH2 F NH-ethyl amino acid amino acid NH2 F NH-acetyl amino acid amino acid NH2 F OH amino acid amino acid NH2 F OMe amino acid amino acid NH2 F OEt amino acid amino acid NH2 F 0-cyclopropyl amino acid amino acid NH2 F 0-acetyl amino acid amino acid NH2 F SH amino acid amino acid NH2 F SMe amino acid amino acid NH2 F SEt amino acid amino acid NH2 F S-cyclopropyl amino acid amino acid NH2 F F amino acid amino acid NH2 F Cl amino acid arnino acid NH2 F Br amino acid amino acid NH2 F I amino acid H NH2 F H amino acid NH2 F NH2 amino acid H NH2 F NH-cyclopropyl amino acid H NH2 F NH-methyl amino acid H NH2 F NH-ethyl amino acid H NH2 F NH-acetyl amino acid H NH2 F OH R'R'X'X'Y amino acid HR3-NH2 F OMe amino acid H NH2 F OEt amino acid F0-cyclopropyl amino acid H NH2 F 0-acetyl amino acid HAN2 FISH amino acid H NH2 F SMe amino acid H NH2 F SEt amino acid H NH2 F S-cyclopropyl amino acid H NH2 F F amino acid H NH2 F C1 amino acid H NH2 F Br amino acid H NH2 F I amino acid acyl NH2 F H amino acid acyl NH2 F NH2 amino acid acyl NH2 F NH-cyclopropyl amino acid acyl NH2 F NH-methyl amino acid acyl NH2 F NH-ethyl amino acid acyl NH2 F NH-acetyl amino acid acyl NH2 F OH amino acid acyl NH2 F OMe amino acid acyl NH2 F OEt amino acid acyl NH2 F 0-cyclopropyl amino acid acyl NH2 F 0-acetyl amino acid acyl NH2 F SH amino acid acyi_ NH2 F SMe amino acid acyl NH2 F SEt amino acid ac 1 NHZ F S-c clo ro 1 amino acid acyl NH2 F F amino acid acyl NH2 F C1 amino acid acyl NH2 F Br amino acid acyl NH2 F I acyl H NH2 Br H acyl H NH2 Br NH2 acyl H NH2 Br NH-c clo ro 1 acyl H NH2 Br NH-methyl acyl H NH2 Br NH-ethyl acyl H NH2 Br NH-acetyl acyl H NH2 Br OH acyl H NH2 Br OMe acyl H NH2 Br OEt acyl H NH2 Br 0-cyclopropyl acyl H NH2 Br 0-acetyl acyl H NH2 Br SH acyl H NH2 Br SMe acyl H _ NH2 Br SEt acyl H NH2 Br S-cyclopropyl acyl H NH2 Br F R2 R3 Xl XZ acyl H NH2 Br C1 acyl H NH2 Br Br acyl H NH2 Br I acyl acyl NH2 Br H acyl acyl NH2 Br NH2 acyl acyl NH2 Br NH-cyclopropyl acyl acyl NH2 Br NH-methyl acyl acyl NH2 Br NH-ethyl acyl acyl NH2 Br NH-acetyl acyl acyl NH2 Br OH acyl acyl NH2 Br OMe acyl acyl NH2 Br OEt acyl acyl NH2 Br 0-cyclopropyl acyl acyl NH2 Br 0-acetyl acyl acyl NH2 Br SH acyl acyl NH2 Br SMe acyl acyl NH2 Br SEt acyl acyl NH2 Br S-cyclopropyl acyl acyl NH2 Br F acyl acyl NH2 Br Cl acyl acyl NH2 Br Br acyl acyl NH2 Br I acyl amino acid NH2 Br H acyl amino acid NH2 Br NH2 acyl amino acid NH2 Br NH-c clo ro yl acyl amino acid NH2 Br NH-methyl acyl amino acid NH2 Br NH-ethyl acyl amino acid NH2 Br NH-acetyl acyl amino acid NH2 Br OH acyl amino acid NH2 Br OMe acyl amino acid NH2 Br OEt acyl amino acid NH2 Br 0-cyclopropyl acyl amino acid NH2 Br 0-acetyl acyl amino acid NH2 Br SH acyl amino acid NH2 Br SMe acyl amino acid NH2 Br SEt acyl amino acid NH2 Br S-cyclopropyl acyl amino acid NH2 Br F acyl amino acid NH2 Br Cl acyl amino acid NH2 Br Br acyl amino acid NH2 Br I H acyl NH2 Br H H acyl NH2 Br NH2 H acyl NH2 Br NH-cyclopropyl H acyl NH2 Br NH-methyl H acyl NH2 Br NH-ethyl H acyl NH2 Br NH-acetyl R R3 X^ XZ H acyl NH2 Br OH H acyl NH2 OMe H acyl NH2 Br OEt H acyl NH2 Br O-cyclopropyl H acyl NH2 Br 0-acetyl H acyl NH2 Br SH H acyl NH2 Br SMe H acyl NH2 Br SEt H acyl NH2 Br S-cyclopropyl H acyl NH2 Br F H acyl NH2 Br C1 H acyl NH2 Br Br H acyl NH2 Br I H amino acid NH2 Br H H amino acid NHZ Br NH2 H amino acid NH2 Br NH-cyclopropyl H amino acid NH2 Br NH-methyl H amino acid NH2 Br NH-ethyl H amino acid NH2 Br NH-acetyl H amino acid NH2 Br OH H amino acid NH2 Br OMe H amino acid NH2 Br OEt H amino acid NH2 Br 0-cyclopropyl H amino acid NH2 Br 0-acetyl H amino acid NH2 Br SH H amino acid NH2 Br SMe H amino acid NH2 Br SEt H amino acid NH2 Br S-cyclopropyl H amino acid NH2 Br F H amino acid NH2 Br Cl H amino acid NH2 Br Br H amino acid NH2 Br I amino acid amino acid NH2 Br H amino acid amino acid NH2 Br NH2 amino acid amino acid NH2 Br NH-cyclopropyl amino acid amino acid NH2 Br NH-methyl amino acid amino acid NH2 Br NH-ethyl amino acid amino acid NH2 Br NH-acetyl amino acid amino acid NH2 Br OH amino acid amino acid NH2 Br OMe amino acid amino acid NH2 Br OEt amino acid amino acid NH2 Br 0-cyclopropyl amino acid amino acid NH2 Br 0-acetyl amino acid amino acid NH2 Br SH amino acid amino acid NH2 Br SMe amino acid amino acid NH2 Br SEt amino acid amino acid NH2 Br S-cyclopropyl RZ R3 Xl XZ amino acid amino acid NH2 Br F amino acid amino acid NH2 Br ci amino acid amino acid NH2 Br Br amino acid amino acid NH2 Br I amino acid H NH2 Br H amino acid H NH2 Br NH2 amino acid H NH2 Br NH-cyclopropyl amino acid H NH2 Br NH-methyl amino acid H NH2 Br NH-ethyl amino acid H NH2 Br NH-acetyl amino acid H NH2 Br OH amino acid H NH2 Br OMe amino acid H NH2 Br OEt amino acid H NH2 Br O-cyclopropyl amino acid H NH2 Br 0-acetyl amino acid H NH2 Br SH amino acid H NH2 Br SMe amino acid H NH2 Br SEt amino acid H NH2 Br S-cyclopropyl amino acid H NH2 Br F amino acid H NH2 Br ci amino acid H NH2 Br Br amino acid H NH2 Br I amino acid acyl NH2 Br H amino acid acyl NH2 Br NH2 amino acid acyl NH2 Br NH-cyclopropyl amino acid acyl NH2 Br NH-methyl amino acid acyl NH2 Br NH-ethyl amino acid acyl NH2 Br NH-acetyl amino acid acyl NH2 Br OH amino acid acyl NH2 Br OMe amino acid acyl NH2 Br OEt amino acid acyl NH2 Br O-cyclopropyl amino acid acyl NH2 Br 0-acetyl amino acid acyl NH2 Br SH amino acid acyl NH2 Br SMe amino acid acyl NH2 Br SEt amino acid acyl NH2 Br S-cyclopropyl amino acid acyl NH2 Br F amino acid acyl NH2 Br ci amino acid acyl NH2 Br Br amino acid acyl NH2 Br I acyl H NH2 C1 H acyl H NH2 C1 NH2 acyl H NH2 Cl NH-cyclopropyl acyl H NH2 C1 NH-methyl acyl H NH2 C1 NH-ethyl R R3 X'XZ acyl H NH2 C1 NH-acetyl acyl H NH2 C1 OH acyl H NH2 C1 OMe acyl H NH2 Cl OEt acyl H NH2 Cl O-cyclopropyl acyl H NH2 C1 O-acetyl acyl H NH2 C1 SH acyl H NH2 C1 SMe acyl H NH2 Cl SEt acyl H NH2 Cl S-cyclopropyl acyl H NH2 Cl F acyl H NH2 C1 C1 acyl H NH2 C1 Br acyl H NH2 C1- acyl acyl NH2 Cl H acyl acyl NH2 C1 NH2 acyl acyl NH2 Cl NH-cyclopropyl acyl acyl NH2 C1 NH-methyl acyl acyl NH2 C1 NH-ethyl acyl acyl NH2 C1 NH-acetyl acyl acyl NH2 C1 OH acyl acyl NH2 C1 OMe acyl acyl NH2 C1 OEt acyl acyl NH2 Cl O-cyclopropyl acyl acyl NH2 C1 O-acetyl acyl acyl NH2 C1 SH acyl acyl NH2 C1 SMe acyl acyl NH2 C1 SEt acyl acyl NH2 C1 S-cyclopropyl acyl acyl NH2 C1 F acyl acyl NH2 C1 C1 acyl acyl NH2 C1 Br acyl acyl NH2 C1 acyl amino acid NH2 Cl H acyl amino acid NH2 Cl NH2 acyl amino acid NH2 Cl NH-cyclopropyl acyl amino acid NH2 Cl NH-methyl acyl amino acid NH2 C1 NH-ethyl acyl amino acid NH2 C1 NH-acetyl acyl amino acid NH2 Cl OH acyl amino acid NH2 Cl OMe acyl amino acid NH2 Cl OEt acyl amino acid NH2 Cl O-cyclopropyl acyl amino acid NH2 Cl O-acetyl f acyl amino acid NH2 C1 SH acyl amino acid NH2 Cl SMe acyl amino acid NH2 Cl SEt R R X X Y acyl amino acid NH2 Cl S-cyclopropyl acyl amino acid NH2 Cl F acyl amino acid NH2 C1 C1 acyl amino acid NH2 Cl Br ac I amino acid NHz Cl I H acyl NH2 C1 H H acyl NH2 C1 NH2 H acyl NH2 C1 NH-cyclopropyl H acyl NH2 C1 NH-methyl H acyl NH2 C1 NH-ethyl H acyl NH2 C1 NH-acetyl H acyl NH2 C1 OH H acyl NH2 C1 OMe H acyl NH2 Cl OEt H acyl NH2 Cl 0-cyclopropyl H acyl NH2 C1 O-acetyl H acyl NH2 C1 SH acyl NH2 C1 SMe H acyl NH2 C1 SEt H acyl NH2 Cl S-cyclopropyl H acyl NH2 C1 F H acyl NH2 C1 C1 H acyl NH2 C1 Br H acyl NH2 Cl I H amino acid. NH2 C1 H H amino acid NH2 C1 NH2 H amino acid NH2 Cl NH-cyclopropy1 H amino acid NH2 Cl NH-methyl H amino acid NH2 Cl-ethyl H amino acid NH2 C1 NH-acetyl H amino acid NH2 Cl OH H amino acid NH2 Cl OMe H amino acid NH2 Cl OEt H amino acid NH2 Cl O-cyclopropyl H amino acid NH2 Cl 0-acetyl H amino acid NH2 Cl SH H amino acid NH2 Cl SMe H amino acid NH2 Cl SEt H amino acid NH2 Cl S-cyclopropyl H amino acid NH2 C1 F H amino acid NH2 Cl Cl H amino acid NH2 ci Br H amino acid NH2 C1 I amino acid amino acid NH2 C1 H amino acid amino acid NH2 Cl NH2 amino acid amino acid NH2 Cl NH-cyclopropyl amino acid amino acid NH2 C1 NH-methyl R R X X Y amino acld ammo acid NH2 C1 NH-ethyl amino acld ammo acid NH2 C1 NH-acetyl amino acid amino acid NH2 Cl OH amino acid amino acid NH2 Cl OMe amino acid amino acid NH2 Cl OEt amino acid amino acid NH2 Cl O-cyclopropyl amino acid amino acid NH2 Cl O-acetyl amino acid amino acid NH2 C1 SH amino acid amino acid NH2 C1 SMe amino acid amino acid NH2 Cl SEt amino acid amino acid NH2 Cl S-cyclopro l amino acid amino acid NH2 C1 F amino acid amino acid NH2 C1 C1 amino acid amino acid NH2 C1 Br amino acid amino acid NH2 C1 I amino acid H NH2 C1 H amino acid H NH2 Cl NH2 amino acid H NH2 Cl NH-cyclopropyl amino acid H NH2 Cl NH-methyl amino acid H NH2 Cl NH-ethyl amino acid H NH2 C1 NH-acetyl amino acid H NH2 ci OH amino acid H NHZ CI OMe amino acid H NH2 C1 OEt amino acid H NH2 Cl O-cyclopropyl amino acid H NH2 Cl 0-acetyl amino acid H NH2 Cl SH amino acid H NH2 Cl SMe amino acid H NH2 Cl SEt amino acid H NHz Cl S-cyclo ro 1 amino acid H NH2 Cl F amino acid H NH2 Cl Cl amino acid H NH2 C1 Br amino acid H NH2 Cl I amino acid acyl NH2 ci H amino acid acyl NH2 Cl NH2 amino acid acyl NH2 Cl NH-cyclopropyI amino acid acyl NH2 C1 NH-methyl amino acid acyl NH2 C1 NH-ethyl amino acid acyl NH2 C1 NH-acetyl amino acid acyl NH2 C1 OH amino acid acyl NH2 Cl OMe amino acid acyl NH2 Cl OEt amino acid Cl 0-cyclopropyl amino acid acyl NH2 Cl O-acetyl amino acid acyl NH2 Cl SH amino acid acyl NH2 C1 SMe R R X X Y amino acid acyl NH2 C1 | SEt amino acid ac 1 NHZ Cl S-cyclopropyl amino acid acyl NH2 Cl F amino acid acyl NH2 C1 C1 amino acid acyl NH2 Cl Br amino acid acyl NH2 C1 I acyl H NH2 SH H acyl H NH2 SH NH2 acyl H NH2 SH NH-cyclopropyl acyl H NH2 SH NH-methyl acyl H NH2 SH NH-ethyl acyl H NH2 SH NH-acetyl acyl H NH2 SH OH acyl H NH2 SH OMe acyl H NH2 SH OEt acyl H NH2 SH 0-cyclopropyl acyl H NH2 SH 0-acetyl acyl H NH2 SH SH acyl H NH2 SH SMe acyl H NH2 SH SEt acyl H NH2 SH S-cyclopropyl acyl H NH2 SH F acyl H NH2 SH ci acyl H NH2 SH Br acyl H NH2 SH I acyl acyl NH2 SH H acyl acyl NH2 SH NH2 acyl acyl NH2 SH NH-c clo ro yl acyl acyl NH2 SH NH-methyl acyl acyl NH2 SH NH-ethyl acyl acyl NH2 SH NH-acetyl acyl acyl NH2 SH OH acyl acyl NH2 SH OMe acyl acyl NH2 SH OEt acyl acyl NH2 SH 0-cyclopropyl acyl acyl NH2 SH 0-acetyl acyl acyl NH2 SH SH acyl acyl NH2 SH SMe acyl acyl NH2 SH SEt acyl acyl NH2 SH S-cyclopropyl acyl acyl NH2 SH F acyl acyl NH2 SH Cl acyl acyl NH2 SH Br acyl acyl NH2 SH I acyl amino acid NH2 SH H acyl amino acid NH2 SH NH2 acyl amino acid NH2 SH NH-cyclopropyl R2 R3 Xl X2 ~ acyl amino acid NH2 SH NH-methyl acyl amino acid NH2 SH NH-ethyl acyl amino acid NH2 SH NH-acetyl acyl amino acid NH2 SH OH acyl amino acid NH2 SH OMe acyl amino acid NH2 SH OEt acyl amino acid NH2 SH 0-cyclopropyl A A acyl amino acid NH2 SH 0-acetyl acyl amino acid NH2 SH SH acyl amino acid NH2 SH SMe acyl amino acid NH2 SH SEt acyl amino acid NH2 SH S-cyclopropyl acyl amino acid NH2 SH F acyl amino acid NH2 SH Cl acyl amino acid NH2 SH Br acyl amino acid NH2 SH I H acyl NH2 SH H H acyl NH2 SH NH2 H acyl NH2 SH NH-c clo ro yl H acyl NH2 SH NH-methyl H acyl NH2 SH NH-ethyl H acyl NH2 SH NH-acetyl H acyl NH2 SH OH H acyl NH2 SH OMe H acyl NH2 SH OEt H acyl NH2 SH 0-cyclopropyl H acyl NH2 SH 0-acetyl H acyl NH2 SH SH H acyl NH2 SH SMe H acyl NH2 SH SEt H acyl NH2 SH S-cyclopropyl H acyl NH2 SH F H acyl NH2 SH ci H acyl NH2 SH Br H acyl NH2 SH I H amino acid NH2 SH H H amino acid NH2 SH NS, H amino acid NH2 SH NH-cyclopropyl H amino acid NH2 SH NH-methyl H amino acid NH2 SH Nu-ethyl H amino acid NH2 SH NH-acetyl H amino acid NH2 SH OH H amino acid NH2 SH OMe H amino acid NH2 SH OEt H amino acid NH2 SH 0-cyclopropyl H amino acid NH2 SH 0-acetyl H amino acid NH2 SH SH R2 R3 Xl X2 H amino acid NH2 SH SMe H amino acid NH2 SH SEt H amino acid NH2 SH S-cyclopropyi H amino acid NH2 SH F H amino acid NH2 SH Cl H amino acid NH2 SH Br H amino acid NH2 SH I amino acid amino acid NH2 SH H amino acid amino acid NH2 SH NH2 amino acid amino acid NH2 SH NH-cyclopropyl amino acid amino acid NH2 SH NH-methyl amino acid amino acid NH2 SH NH-ethyl amino acid amino acid NH2 SH NH-acetyl amino acid amino acid NH2 SH OH amino acid amino acid NH2 SH OMe amino acid amino acid NH2 SH OEt amino acid amino acid NH2 SH 0-cyclopropyl amino acid amino acid NH2 SH 0-acetyl amino acid amino acid NH2 SH SH amino acid amino acid NH2 SH SMe amino acid amino acid NH2 SH SEt amino acid amino acid NH2 SH S-cyclopropyl amino acid amino acid NH2 SH F amino acid amino acid NH2 SH Cl amino acid amino acid NH2 SH Br amino acid amino acid NH2 SH I amino acid H NH2 SH H amino acid H NH2 SH NH2 amino acid H NH2 SH NH-cyclopropyl amino acid H NH2 SH NH-methyl amino acid H NH2 SH NH-ethyl amino acid H NH2 SH NH-acetyl amino acid H NH2 SH OH amino acid H NH2 SH OMe amino acid H NH2 SH OEt amino acid H NH2 SH O-cyclopropyl amino acid H NH2 SH O-acetyl amino acid H NH2 SH SH amino acid H NH2 SH SMe amino acid H NH2 SH SEt amino acid H NH2 SH S-cyclopropyl amino acid H NH2 SH F amino acid H NH2 SH Cl amino acid H NH2 SH Br amino acid H NH2 SH I amino acid acyl NH2 SH H amino acid acyl NH2 SH NH2 R R X X Y amino acid acyl NH2 SH NH-cyclopropyl amino acid acyl NH2 SH NH-methyl amino acid acyl NH2 SH NH-ethyl amino acid acyl NH2 SH NH-acetyl amino acid acyl NH2 SH OH amino acid acyl NH2 SH OMe amino acid acyl NH2 SH OEt amino acid acyl NH2 SH O-cyclopropyl amino acid acyl NH2 SH O-acetyl amino acid acyl NH2 SH SH amino acid acyl NH2 SH SMe amino acid acyl NH2 SH SEt amino acid acyl NH2 SH S-cyclopropyl amino acid acyl NH2 SH F amino acid acyl NH2 SH Cl amino acid acyl NH2 SH Br amino acid acyl NH2 SH I acyl H F SH H acyl H F SH NH2 acyl H F SH NH-cyclopropyl acyl H F SH NH-methyl acyl H F SH NH-ethyl acyl H F SH NH-acetyl S acyl H F SH OH acyl H F SH OMe acyl H F SH OEt acyl 0-cyclopropyl acyl H F SH 0-acetyl acyl H F SH SH acyl H F SH SMe acyl H F SH SEt acyl H F SH S-cyclopropyl acyl H F SH F acyl H F SH ci acyl H F SH Br acyl H F SH I acyl acyl F SH I H acyl acyl F SH acyl acyl F SH _ NH-cyclopropyl acyl acyl F SH NH-methyl acyl acyl F SH NH-ethyl acyl acyl F SH NH-acetyl acyl acyl F SH OH acyl acyl F SH OMe acyl acyl F SH OEt acyl acyl F SH 0-cyclopropyl acyl acyl F SH O-acetyl R2 R3 Xl x2 acyl acyl F SH SH acyl acyl F SH SMe acyl acyl F SH SEt acyl acyl F SH S-cyclopropyl acyl acyl F SH F acyl acyl F SH C1 acyl acyl F SH Br acyl acyl F SH I acyl amino acid F SH H acyl amino acid F SH NH2 acyl amino acid F SH NH-cyclopropyl acyl amino acid F SH NH-methyl acyl amino acid F SH NH-ethyl acyl amino acid F SH NH-acetyl acyl amino acid F SH OH acyl amino acid F SH OMe acyl amino acid F SH OEt acyl amino acid F SH O-cyclopropyl acyl amino acid F SH 0-acetyl acyl amino acid F SH SH acyl amino acid F SH SMe acyl amino acid F SH SEt acyl amino acid F SH S-cyclopropyl acyl amino acid F SH F acyl amino acid F SH Cl acyl amino acid F SH Br acyl amino acid F SH I H acyl F SH H H acyl F SH NH2 H ac 1 F SH NH-c clo ro 1 , S S H acyl F SH NH-methyl H acyl F SH NH-ethyl H acyl F SH NH-acetyl H acyl F SH OH H acyl F SH OMe H acyl F SH OEt H 0-cyclopropyl H acyl F SH 0-acetyl H acyl F SH SH H acyl F SH SMe H acyl F SH SEt H acyl F SH S-cyclopropyl H acyl F SH F H acyl F SH C1 H acyl F SH Br H acyl F SH I H amino acid F SH H R2 R3 Xl x2 H amino acid F SH NH2 H amino acid F SH NH-cyclopropyl H amino acid F SH NH-methyl H amino acid F SH NH-ethyl H amino acid F SH NH-acetyl H amino acid F SH OH H amino acid F SH OMe H amino acid F SH OEt H amino acid F SH 0-cyclopropyl H amino acid F SH O-acetyl H amino acid F SH SH H amino acid F SH SMe H amino acid F SH SEt H amino acid F SH S-cyclopropyl H amino acid F SH F H amino acid F SH Cl H amino acid F SH Br H amino acid F SH I amino acid amino acid F SH H amino acid amino acid F SH NH2 amino acid amino acid F SH NH-cyclopropyl amino acid amino acid F SH NH-methyl amino acid amino acid F SH NH-ethyl amino acid amino acid F SH NH-acetyl amino acid amino acid F SH OH amino acid amino acid F SH OMe amino acid amino acid F SH OEt amino acid amino acid F SH 0-cyclopropyl amino acid amino acid F SH 0-acetyl amino acid amino acid F SH SH amino acid amino acid F SH SMe amino acid amino acid F SH SEt amino acid amino acid F SH S-cyclopropyl amino acid amino acid F SH F amino acid amino acid F SH Cl amino acid amino acid F SH Br amino acid amino acid F SH I amino acid H F SH H amino acid H F SH NH2 amino acid H F SH NH-cyclopropyl amino acid H F SH NH-methyl amino acid H F SH NH-ethyl amino acid H F SH NH-acetyl amino acid H F SH OH amino acid H F SH OMe amino acid H F SH OEt amino acid H F SH O-cyclopropyl R R X X Y amino acid H F SH 0-acetyl amino acid H F SH SH amino acid H F SH SMe amino acid H F SH SEt amino acid H F SH S-c clo ro 1 amino acid H F SH F amino acid H F SH Cl amino acid H F SH Br amino acid H F SH I amino acid acyl F SH H amino acid acyl F SH NH2 amino acid acyl F SH NH-cyclopropyl amino acid acyl F SH NH-methyl amino acid acyl F SH NH-ethyl amino acid acyl F SH NH-acetyl amino acid acyl F SH OH amino acid acyl F SH OMe amino acid acyl F SH OEt amino acid 0-cyclopropyl amino acid acyl F SH 0-acetyl amino acid acyl F SH SH amino acid acyl F SH SMe amino acid acyl F SH SEt amino acid acyl F SH S-cyclopropyl amino acid acyl F SH F amino acid acyl F SH Cl amino acid acyl F SH Br amino acid acyl F SH I acyl H F Br H acyl H F Br NH2 acyl H F Br NH-cyclopropyl acyl H F Br NH-methyl acyl H F Br NH-ethyl acyl H F Br NH-acetyl S acyl H F Br OH acyl H F Br OMe acyl H F Br OEt acyl H F Br O-cyclopropyl acyl H F Br 0-acetyl acyl H F Br SH acyl H F Br SMe acyl H F Br SEt acyl H F Br S-cyclopropyl acyl H F Br F acyl H F Br C1 acyl H F Br Br acyl H F Br I R R3 Xl x2 acyl acyl F Br H acyl acyl F Br NH2 acyl acyl F Br NH-cyclopropyl acyl acyl F Br NH-methyl acyl acyl F Br NH-ethyl acyl acyl F Br NH-acetyl acyl acyl F Br OH acyl acyl F Br OMe acyl acyl F Br OEt acyl acyl F Br 0-cyclopropyl acyl acyl F Br 0-acetyl acyl acyl F Br SH acyl acyl F Br SMe acyl acyl F Br SEt acyl acyl F Br S-cyclo ro 1 acyl acyl F Br F acyl acyl F Br C1 acyl acyl F Br Br acyl acyl F Br I acyl amino acid F Br H acyl amino acid F Br NH2 acyl amino acid F Br NH-cyclopropyl acyl amino acid F Br NH-methyl acyl amino acid F Br NH-ethyl acyl amino acid F Br NH-acetyl # acyl amino acid F Br OH acyl amino acid F Br OMe acyl amino acid F Br OEt acyl amino acid F Br 0-cyclopropyl ac 1 amino acid F Br O-acet 1 acyl amino acid F Br SH acyl amino acid F Br SMe acyl amino acid F Br SEt acyl amino acid F Br S-cyclopropyl acyl amino acid F Br F acyl amino acid F Br C1 acyl amino acid F Br Br acyl amino acid F Br I H acyl F Br H H acyl F Br NH2 H acyl F Br NH-cyclopropyl H acyl F Br NH-methyl H ac 1 F Br NH-eth 1 S H acyl F Br NH-acetyl H acyl F Br OH H acyl F Br OMe H acyl F Br OEt R2 R X X Y H acyl F Br 0-cyclopropyl H acyl F Br 0-acetyl H acyl F Br SH H acyl F Br SMe H acyl F Br SEt H ac 1 F Br S-c clo ro 1 H acyl F Br F H acyl F Br C1 H acyl F Br Br H acyl F Br I H amino acid F Br H H amino acid F Br NH2 H amino acid F Br NH-cyclopropyl H amino acid F Br NH-methyl H amino acid F Br NH-ethyl H amino acid F Br NH-acetyl H amino acid F Br OH H amino acid F Br OMe H amino acid F Br OEt H amino acid F Br O-cyclopropyl H amino acid F Br 0-acetyl S H amino acid F Br SH H amino acid F Br SMe H amino acid F Br SEt H amino acid F Br S-cyclopropyl H amino acid F Br F H amino acid F Br Cl H amino acid F Br Br H amino acid F Br I amino acid amino acid F Br H amino acid amino acid F Br NH2 amino acid amino acid F Br NH-c clo ro 1 amino acid amino acid F Br NH-methyl amino acid amino acid F Br NH-ethyl amino acid amino acid F Br NH-acetyl amino acid amino acid F Br OH amino acid amino acid F Br OMe amino acid amino acid F Br OEt amino acid amino acid F Br O-cyclopropyl amino acid amino acid F Br O-acetyl amino acid amino acid F Br SH amino acid amino acid F Br SMe amino acid amino acid F Br SEt amino acid amino acid F Br S-cyclopropyl amino acid amino acid F Br F amino acid amino acid F Br Cl amino acid amino acid F Br Br R2 R3 Xl x2 amino acid amino acid F Br I amino acid H F Br H amino acid H F Br NH2 amino acid H F Br NH-cyclopropyl amino acid H F Br NH-methyl amino acid H F Br NH-ethyl amino acid H F Br NH-acetyl amino acid H F Br OH amino acid H F Br OMe amino acid H F Br OEt amino acid 0-cyclopropyl amino acid H F Br 0-acetyl amino acid H F Br SH amino acid H F Br SMe amino acid H F Br SEt amino acid H F Br S-cyclopropyl amino acid H F Br F amino acid H F Br Cl amino acid H F Br Br amino acid H F Br I amino acid acyl F Br H amino acid acyl F Br NH2 amino acid ac 1 F Br NH-c clo ro 1 amino acid acyl F Br NH-methyl amino acid acyl F Br NH-ethyl amino acid acyl F Br NH-acetyl S amino acid acyl F Br OH amino acid acyl F Br OMe amino acid acyl F Br OEt amino acid 0-cyclopropyl amino acid acyl F Br 0-acetyl amino acid acyl F Br SH amino acid acyl F Br SMe amino acid acyl F Br SEt amino acid acyl F Br S-c lopropyl amino acid acyl F Br F amino acid acyl F Br C1 amino acid acyl F Br Br amino acid acyl F Br I acyl H Br F H acyl H Br F NH2 acyl H Br F NH-cyclopropyl acyl H Br F NH-methyl acyl H Br F NH-ethyl acyl H Br F NH-acetyl acyl H Br F OH acyl H Br F OMe R R X X Y acyl H Br F OEt acyl H Br F 0-cyclopropyl acyl H Br F O-acetyl acyl H Br F SH acyl H Br F SMe acyl H Br F SEt acyl H Br F S-cyclopropyl acyl H Br F F acyl H Br F C1 acyl H Br F Br acyl H Br F acyl acyl Br F H acyl acyl Br F NH2 acyl acyl Br F NH-cyclopropyl acyl acyl Br F NH-methyl acyl acyl Br F NH-ethyl acyl acyl Br F NH-acetyl acyl acyl Br F OH acyl acyl Br F OMe acyl acyl Br F OEt acyl acyl Br F O-cyclopropyl acyl acyl Br F 0-acetyl acyl acyl Br F SH acyl acyl Br F SMe acyl acyl Br F SEt ac 1 acyl Br F S-c clo ro 1 acyl acyl Br F F acyl acyl Br F C1 acyl acyl Br F Br acyl acyl Br F I acyl amino acid Br F H acyl amino acid Br F NH2 acyl amino acid Br F NH-c clo ro 1 acyl amino acid Br F NH-methyl acyl amino acid Br F NH-ethyl acyl amino acid Br F NH-acetyl ac 1 amino acid Br F OH acyl amino acid Br F OMe acyl amino acid Br F OEt acyl amino acid Br F 0-cyclopropyl acyl amino acid Br F O-acetyl acyl amino acid Br F SH acyl amino acid Br F SMe acyl amino acid Br F SEt acyl amino acid Br F S-cyclopropyl acyl amino acid Br F F acyl amino acid Br F C1 R2 R'X X Y acyl amino acid Br F Br acyl amino acid Br F I H acyl Br F H H acyl Br F NH2 H acyl Br F NH-cyclopropyl H acyl Br F NH-methyl H acyl Br F NH-ethyl H acyl Br F NH-acetyl H acyl Br F OH H acyl Br F OMe H acyl Br F OEt H ac 1 Br F O-c clo ro 1 H acyl Br F 0-acetyl H acyl Br F SH H acyl Br F SMe H acyl Br F SEt H acyl Br F S-cyclopropyl H acyl Br F F H acyl Br F C1'-- H acyl Br F Br H acyl Br F I H amino acid Br F H H amino acid Br F NH2 H amino acid Br F NH-cyclopropyl H amino acid Br F NH-methyl H amino acid Br F NH-ethyl H amino acid Br F NH-acetyl H amino acid Br F OH H amino acid Br F OMe H amino acid Br F OEt H amino acid Br F 0-cyclopropyl H amino acid Br F 0-acetyl H amino acid Br F SH H amino acid Br F SMe H amino acid Br F SEt H amino acid Br F S-cyclopropyl H amino acid Br F F H amino acid Br F C1 H amino acid Br F Br H amino acid Br F I amino acid amino acid Br F H amino acid amino acid Br F NH2 amino acid amino acid Br F NH-cyclopropyl amino acid amino acid Br F NH-methyl amino acid amino acid Br NH-ethyl amino acid amino acid Br F NH-acetyl amino acid amino acid Br F OH R R3 Xl x2 amino acid amino acid Br F OMe amino acid amino acid Br F OEt amino acid amino acid Br F 0-cyclopropyl amino acid amino acid Br F 0-acetyl amino acid amino acid Br F SH amino acid amino acid Br F SMe amino acid amino acid Br F SEt amino acid amino acid Br F S-cyclopropyl amino acid amino acid Br F F amino acid amino acid Br F Cl amino acid amino acid Br F Br amino acid amino acid Br F I amino acid H Br F H amino acid H Br F NH2 amino acid H Br F NH-cyclopropyl amino acid H Br F NH-methyl amino acid H Br F NH-ethyl # amino acid H Br F NH-acetyl amino acid H Br F OH amino acid H Br F OMe amino acid H Br F OEt amino acid H Br F O-c clo ro 1 amino acid H Br F 0-acetyl amino acid H Br F SH amino acid H Br F SMe amino acid H Br F SEt amino acid H Br F S-cyclopropyl amino acid H Br F F amino acid H Br F Cl amino acid H Br F Br amino acid H Br F I amino acid acyl Br F H amino acid acyl Br F NH2 amino acid acyl Br F NH-cyclopropyl amino acid acyl Br F NH-methyl amino acid acyl Br F NH-ethyl amino acid acyl Br F NH-acetyl amino acid acyl Br F OH amino acid acyl Br F OMe amino acid acyl Br F OEt amino acid acyl Br F 0-cyclopropyl amino acid acyl Br F 0-acetyl M amino acid acyl Br F SH amino acid acyl Br F SMe amino acid acyl Br F SEt amino acid ac 1 Br F S-c clo ro 1 amino acid acyl Br F F R R X X Y amino acid acyl Br F C1 amino acid acyl Br F Br amino acid acyl Br F I acyl H F C1 H acyl H F C1 NH2 acyl H F C1 _ NH-cyclopropffl acyl H F C1 NH-methyl acyl H F C1 NH-ethyl acyl H F ci NH-acetyl acyl H F C1 OH acyl H F C1 OMe acyl H F C1 OEt acyl H F Cl O-cyclopropyl acyl H F C1 O-acetyl acyl H F C1 SH acyl H F C1 SMe acyl H F C1 SEt acyl H F C1 S-cyclopropyl acyl H F C1 F acyl H F C1 C1 acyl H F C1 Br acyl H F C1 acyl acyl F C1 H acyl acyl F C1 NH2 acyl acyl F C1 NH-cyclopropyl acyl acyl F C1 NH-methyl acyl acyl F C1 NH-ethyl acyl acyl F C1 NH-acetyl acyl acyl F C1 OH acyl _ acyl F C1 OMe acyl acyl F C1 OEt ac 1 ac 1 F Cl O-c clo ro 1 acyl _ acyl F C1 O-acetyl acyl acyl F C1 SH acyl acyl F C1 SMe acyl acyl F C1 SEt ac 1 ac 1 F Cl S-c clo ro 1 acyl acyl F C1 F acyl acyl F C1 C1 acyl acyl F Cl Br acyl acyl F C1 acyl amino acid F Cl H acyl amino acid F C1 NH2 acyl amino acid F Cl NH-cyclopropyl acyl amino acid F C1 NH-methyl acyl amino acid F Cl NH-ethyl acyl amino acid F C1 NH-acetyl R R X X Y acyl amino acid F C1 OH acyl amino acid _F C1 OMe acyl amino acid F Cl OEt ac 1 amino acid F Cl O-c clo ro 1 acyl amino acid F C1 O-acetyl acyl amino acid F C1 SH acyl amino acid F Cl SMe acyl amino acid F C1 SEt acyl amino acid F Cl S-cyclo ro 1 acyl amino acid F C1 F acyl amino acid F C1 C1 acyl amino acid F C1 Br acyl amino acid F C1 I H acyl F C1 H acyl F C1 NH2 H ac 1 F Cl NH-c clo ro 1 H acyl F C1 NH-methyl H acyl F C1 NH-ethyl H acyl F C1 NH-acetyl H acyl F C1 OH H acyl F C1 OMe H _ acyl F C1 OEt H ac 1 F Cl O-c clo ro 1 H ac 1 F Cl O-acet 1 K H acyl F C1 SH H acyl F C1 SMe H acyl F C1 SEt H acyl F C1 S-cyclopropyl H acyl F C1 F H acyl F C1 C1 H acyl F C1 Br H acyl F C1 I H amino acid F ci H H amino acid F Cl NH2 H amino acid F Cl NH-cyclopropyl H amino acid F C1 NH-methyl H amino acid F C1 NH-ethyl H amino acid F C1 NH-acetyl H amino acid F C1 OH H amino acid F Cl OMe H amino acid F Cl OEt H amino acid F Cl O-cyclopropyl H amino acid F Cl O-acetyl # H amino acid F C1 SH H amino acid F Cl SMe H amino acid F Cl SEt H amino acid F Cl S-cyclopropyl R R X X Y H amino acid F Cl F H amino acid F Cl Cl H amino acid F Cl Br H amino acid F Cl I amino acid amino acid F Cl H amino acid amino acid F Cl NH2 amino acid amino acid F Cl NH-c clo ro 1 amino acid amino acid F C1 NH-methyl amino acid amino acid F C1 NH-ethyl amino acid amino acid F C1 NH-acetyl amino acid amino acid F Cl OH amino acid amino acid F C1 OMe amino acid amino acid F Cl OEt amino acid amino acid F Cl O-cyclopropyl amino acid amino acid F C1 O-acetyl amino acid amino acid F Cl SH amino acid amino acid F C1 SMe amino acid amino acid C1 SEt amino acid amino acid F Cl S-cyclo ro 1 amino acid amino acid F Cl F amino acid amino acid F Cl Cl amino acid amino acid F Cl Br amino acid amino acid F Cl I amino acid H F C1 H amino acid H F Cl NH2 amino acid H F CI NH-c clo ro 1 amino acid H F C1 NH-methyl amino acid H F Cl NH-ethyl amino acid H F C1 NH-acetyl amino acid H F Cl OH amino acid H F C1 OMe amino acid H F Cl OEt amino acid 0-cyclopropyl amino acid H F C1 O-acetyl amino acid H F ci s amino acid H F C1 SMe amino acid H F Cl SEt amino acid H F Cl S-cyclopropyl amino acid H F CI F amino acid H F Cl Cl amino acid H F Cl Br amino acid H F Cl I amino acid acyl F C1 H 0 amino acid acyl F C1 NH2 amino acid acyl F C1 NH-cyclopropyl amino acid acyl F C1 NH-methyl amino acid acyl F C1 NH-ethyl R2 R3 | Xl x2 _ amino acid acyl F C1 NH-acetyl amino acid acyl F C1 OH amino acid acyl F C1 OMe amino acid acyl F C1 OEt amino acid 0-cyclopropyl amino acid acyl F C1 O-acetyl amino acid acyl F C1 SH amino acid acyl F C1 SMe amino acid acyl F Cl SEt amino acid acyl F Cl S-c clo ro 1 amino acid acyl F C1 F amino acid acyl F C1 C1 amino acid acyl F C1 Br amino acid acyl F C1 I acyl H C1 F H acyl H C1 F NH2 acyl H Cl F NH-c clo ro 1 acyl H C1 F NH-methyl acyl H C1 F NH-ethyl acyl H C1 F NH-acetyl acyl H C1 F OH acyl C1 F OMe acyl H C1 F OEt ac 1 H Cl F O-c clo ro 1 acyl H C1 F O-acetyl acyl H C1 F SH acyl H C1 F SMe acyl H C1 F SEt ac 1 H C1 F S-cyclo ro 1 acyl H C1 F F acyl H C1 F C1 acyl H C1 F Br acyl H C1 F I acyl acyl C1 F H acyl acyl Cl F NH2 ac 1 ac 1 Cl F NH-c clo ro 1 acyl acyl C1 F _ NH-methyl acyl acyl C1 F NH-ethyl acyl acyl Cl F NH-acetyl acyl acyl C1 F OH acyl acyl C1 F OMe acyl acyl C1 F OEt ac 1 ac 1 Cl F O-c clo ro 1 acyl acyl C1 F O-acetyl acyl acyl C1 F SH acyl acyl C1 F SMe acyl acyl C1 F SEt R2 R3 X1 X2 ac 1 ac 1 Cl F S-c clo ro 1 ac 1 ac 1 Cl F F acyl acyl C1 F C1 acyl acyl C1 F Br acyl acyl C1 F I acyl amino acid C1 F H acyl amino acid C1 F NH2 ac 1 amino acid Cl F NH-c clo ro 1 acyl amino acid C1 F NH-methyl acyl amino acid C1 F NH-ethyl acyl amino acid C1 F NH-acetyl acyl amino acid C1 F OH acyl amino acid C1 F OMe acyl amino acid C1 F OEt ac 1 amino acid Cl F O-cyclopropyl ac 1 amino acid Cl F O-ace 1 acyl amino acid C1 F SH acyl amino acid C1 F SMe acyl amino acid C1 F SEt ac 1 amino acid Cl F S-c clo ro 1 ac 1 amino acid Cl F F acyl amino acid Cl F Cl ac 1 amino acid Cl F Br acyl amino acid Cl F I H acyl C1 F H H acyl C1 F NH2 H ac 1 Cl F NH-c clo ro 1 H acvl C1 F NH-methyl f H acyl C1 F NH-ethyl H acyl C1 F NH-acetyl acyl C1 F OH H acyl C1 F OMe H acyl C1 F OEt H ac 1 Cl F O-c clo ro 1 H acyl C1 F O-acetyl H acyl C1 F SH H acyl C1 F _ SMe H acyl C1 F SEt H acyl C1 F S-cyclopropyl H acyl C1 F F H acyl C1 F C1 H acyl C1 F Br H acyl C1 F H amino acid Cl F H H amino acid C1 F NH2 H amino acid Cl F NH-c clo ro 1 H amino acid Cl F NH-methyl R R X X Y H amino acid C1 F NH-ethyl H amino acid Cl F NH-acetyl H amino acid Cl F OH H amino acid Cl F OMe H amino acid Cl F OEt H amino acid CI F O-cyclo ro 1 H amino acid C1 F O-acetyl H amino acid Cl F SH H amino acid Cl F SMe H amino acid Cl F SEt H amino acid Cl F S-c clo ro 1 H amino acid C1 F F H amino acid Cl F Cl H amino acid Cl F Br H amino acid Cl F I amino acid amino acid Cl F H amino acid amino acid Cl F NH2 amino acid amino acid Cl F NH-c clo ro 1 amino acid amino acid C1 F NH-methyl amino acid amino acid C1 F NH-ethyl amino acid amino acid C1 F NH-acetyl amino acid amino acid Cl F OH amino acid amino acid Cl F OMe amino acid amino acid C1 F OEt amino acid amino acid Cl F O-c clo ro 1 amino acid amino acid C1 F O-acetyl amino acid amino acid Cl F SH amino acid amino acid Cl F SMe amino acid amino acid Cl F SEt amino acid amino acid Cl F S-c clo ro 1 amino acid amino acid Cl F F amino acid amino acid Cl F Cl amino acid amino acid Cl F Br amino acid amino acid Cl F I amino acid H Cl F H amino acid H C1 F NH2 amino acid H Cl F NH-c clo ro 1 amino acid H C1 F NH-methyl amino acid H C1 F NH-ethyl amino acid H C1 F NH-acetyl amino acid H Cl F OH amino acid H Cl F OMe amino acid H C1 F OEt amino acid F0-cyclopropyl amino acid H C1 F O-acetyl amino acid H C1 F SH amino acid H C1 F SMe R R X'X Y amino acid H Cl F SEt amino acid H Cl F S-c clo ro 1 amino acid H Cl F F amino acid H Cl F Cl amino acid H Cl F Br amino acid H Cl F I amino acid acyl Cl F H amino acid acyl C1 F NH2 amino acid acyl Cl F NH-cyclo ro 1 amino acid acyl C1 F NH-methyl amino acid acyl C1 F NH-ethyl amino acid acyl C1 F NH-acetyl amino acid acyl Cl F OH amino acid ac 1 Cl F OMe f amino acid acyl C1 F OEt amino acid ac 1 Cl F O-c clo ro 1 amino acid ac 1 Cl F O-ace 1 amino acid acyl Cl F SH amino acid acyl C1 F SMe amino acid acyl C1 F SEt amino acid ac 1 Cl F S-c clo ro 1 amino acid acyl Cl F F amino acid acyl C1 F C1 amino acid acyl C1 F Br amino acid acyl C1 F I acyl H SH H H acyl H SH H NH2 acyl H SH H NH-cyclopropyl acyl H SH H NH-methyl acyl H SH H NH-ethyl acyl SH H NH-acetyl acyl H SH H OH acyl H SH H OMe acyl H SH H OEt acyl H SH H 0-cyclopropyl acyl H SH H 0-acetyl acyl H SH H SH acyl H SH H SMe acyl H SH H SEt acyl H SH H S-cyclopropyl acyl H SH H F acyl H SH H C1 acyl H SH H Br acyl H SH H I acyl acyl SH H H acyl acyl SH H NH2 acyl acyl SH H NH-cyclopropyl R R X X Y acyl acyl SH H NH-methyl acyl acyl SH H NH-ethyl acyl acyl SH H NH-acetyl acyl acyl SH H OH acyl acyl SH H OMe acyl acyl SH H OEt acyl acyl SH H 0-cyclopropyl acyl acyl SH H 0-acetyl acyl acyl SH H SH acyl acyl SH H SMe acyl acyl SH H SEt acyl acyl SH H S-cyclopropyl acyl acyl SH H F acyl acyl SH H C1 acyl acyl SH H Br acyl acyl SH H I acyl amino acid SH H H acyl amino acid SH H NH2 acyl amino acid SH H NH-cyclopropyl acyl amino acid SH H NH-methyl acyl amino acid SH H NH-ethyl acyl amino acid SH H NH-acetyl acyl amino acid SH H OH acyl amino acid SH H OMe acyl amino acid SH H OEt acyl amino acid SH H 0-cyclopropyl acyl amino acid SH H O-acetyl acyl amino acid SH H SH acyl amino acid SH H SMe acyl amino acid SH H SEt acyl amino acid SH H S-cyclopropyl acyl amino acid SH H F acyl amino acid SH H Cl acyl amino acid SH H Br acyl amino acid SH H I H acyl SH H H H acyl SH H NH2 H acyl SH H NH-cyclopropyl H acyl SH H NH-methyl H acyl SH H NH-ethyl H acyl SH H NH-acetyl H acyl SH H OH H acyl SH H OMe H acyl SH H OEt H acyl SH H 0-cyclopropyl H acyl SH H 0-acetyl H acyl SH H SH R2 R3 Xl x2 H acyl SH H SMe H acyl SH H SEt H acyl SH H S-cyclopropyl H acyl SH H F H acyl SH H C1 H acyl SH H Br H acyl SH H I H amino acid SH H H H amino acid SH H NH2 H amino acid SH H NH-cyclopropyl H amino acid SH H NH-methyl H amino acid SH H NH-ethyl H amino acid SH H NH-acetyl H amino acid SH H OH H amino acid SH H OMe H amino acid SH H OEt H amino acid SH H 0-cyclopropyl H amino acid SH H 0-acetyl H amino acid SH H SH H amino acid SH H SMe H amino acid SH H SEt H amino acid SH H S-cyclopropyl H amino acid SH H F H amino acid SH H Cl H amino acid SH H Br H amino acid SH H I amino acid amino acid SH H H amino acid amino acid SH H NH2 amino acid amino acid SH H NH-cyclopropyl amino acid amino acid SH H NH-methyl amino acid amino acid SH H NH-ethyl amino acid amino acid SH H NH-acetyl amino acid amino acid SH H OH amino acid amino acid SH H OMe amino acid amino acid SH H OEt amino acid amino acid SH H 0-cyclopropyl amino acid amino acid SH H 0-acetyl amino acid amino acid SH H SH amino acid amino acid SH H SMe amino acid amino acid SH H SEt amino acid amino acid SH H S-cyclopropyl amino acid amino acid SH H F amino acid amino acid SH H Cl amino acid amino acid SH H Br amino acid amino acid SH H I amino acid H SH H H amino acid H SH H NH2 R R X X Y amino acid H SH H NH-cyclopropyl amino acid H SH H NH-methyl amino acid H SH H NH-ethyl amino acid H SH H NH-acetyl amino acid H SH H OH amino acid H SH H OMe amino acid H SH H OEt amino acid H SH H O-c clo ro 1 amino acid H SH H 0-acetyl amino acid H SH H SH amino acid H SH H SMe amino acid H SH H SEt amino acid H SH H S-cyclopropyl amino acid H SH H F amino acid H SH H Cl amino acid H SH H Br amino acid H SH H I amino acid acyl SH H H amino acid acyl SH H NH2 amino acid acyl SH H NH-cyclopropyl amino acid acyl SH H NH-methyl amino acid acyl SH H NH-ethyl amino acid acyl SH H NH-acetyl amino acid acyl SH H OH amino acid acyl SH H OMe amino acid acyl SH H OEt amino acid acyl SH H 0-cyclopropyl amino acid acyl SH H O-acetyl amino acid acyl SH H SH amino acid acyl SH H SMe amino acid acyl SH H SEt amino acid acyl SH H S-cyclopropyl amino acid acyl SH H F amino acid acyl SH H C1 amino acid acyl SH H Br amino acid acyl SH H I acyl H SH F H acyl H SH F NH2 acyl H SH F NH-cyclopropyl acyl H SH F NH-methyl acyl H SH F NH-ethyl acyl H SH F NH-acetyl acyl H SH F OH acyl H SH F OMe acyl H SH F OEt acyl H SH F O-cyclopropyl acyl H SH F O-acetyl R R3 Xl x2 acyl H SH F SH acyl H SH F SMe acyl H SH F SEt acyl H SH F S-cyclopropyl acyl H SH F F acyl H SH F Cl acyl H SH F Br acyl H SH F I acyl acyl SH F H acyl acyl SH F NH2 ac 1 ac 1 SH F NH-c clo ro 1 acyl acyl SH F NH-methyl acyl acyl SH F NH-ethyl acyl acyl SH F NH-acetyl acyl acyl SH F OH acyl acyl SH F OMe acyl acyl SH F OEt acyl acyl SH F O-cyclopropyl acyl acyl SH F 0-acetyl acyl acyl SH F SH acyl acyl SH F SMe acyl acyl SH F SEt acyl acyl SH F S-cyclopropyl acyl acyl SH F F acyl acyl SH F C1 acyl acyl SH F Br acyl acyl SH F I acyl amino acid SH F H acyl amino acid SH F NH2 acyl amino acid SH F NH-cyclopropy1 acyl amino acid SH F NH-methyl acyl amino acid SH F NH-ethyl S acyl amino acid SH F NH-acetyl acyl amino acid SH F OH acyl amino acid SH F OMe acyl amino acid SH F _ OEt acyl amino acid SH F O-cyclopropyl acyl amino acid SH F 0-acetyl acyl amino acid SH F SH acyl amino acid SH F SMe acyl amino acid SH F SEt acyl amino acid SH F S-cyclopropyl acyl amino acid SH F F acyl amino acid SH F C1 acyl amino acid SH F Br acyl amino acid SH F I H acyl SH F H R2 R X X Y H acyl SH F NH2 H acyl SH F NH-cyclopropyl H acyl SH F NH-methyl H acyl SH F NH-ethyl M H acyl SH F NH-acetyl H acyl SH F OH H acyl SH F OMe H acyl SH F OEt H acyl SH F O-cyclopropyl H acyl SH F 0-acetyl H acyl SH F SH H acyl SH F SMe H acyl SH F SEt H acyl SH F S-cyclopropyl H acyl SH F F H acyl SH F C1 H acyl SH F Br H acyl SH F I H amino acid SH F H H amino acid SH F NH2 H amino acid SH F NH-cyclopropyl H amino acid SH F NH-methyl H amino acid SH F NH-ethyl H amino acid SH F NH-acetyl H amino acid SH F OH H amino acid SH F OMe H amino acid SH F OEt H amino acid SH F O-cyclopropyl H amino acid SH F 0-acetyl H amino acid SH F SH H amino acid SH F SMe H amino acid SH F SEt H amino acid SH F S-cyclopropyl H amino acid SH F F H amino acid SH F C1 H amino acid SH F Br H amino acid SH F I amino acid amino acid SH F H amino acid amino acid SH F NH2 amino acid amino acid SH F NH-cyclopropyl amino acid amino acid SH F NH-methyl amino acid amino acid SH F NH-ethyl amino acid amino acid SH F NH-acetyl amino acid amino acid SH F OH amino acid amino acid SH F OMe amino acid amino acid SH F OEt amino acid amino acid SH F 0-cyclopropyl R2 R3 Xl x2 amino acid amino acid SH F O-acetyl amino acid amino acid SH F SH amino acid amino acid SH F SMe amino acid amino acid SH F SEt amino acid amino acid SH F S-c clo ro 1 amino acid amino acid SH F F amino acid amino acid SH F C1 amino acid amino acid SH F Br amino acid amino acid SH F I amino acid H SH F H amino acid H SH F NH2 amino acid H SH F NH-c clo ro 1 amino acid H SH F NH-methyl amino acid H SH F NH-ethyl amino acid H SH F NH-acetyl amino acid H SH F OH amino acid H SH F OMe amino acid H SH F OEt amino acid H SH F O-cyclo ro 1 amino acid SH F O-acetyl amino acid H SH F SH amino acid H SH F SMe amino acid H SH F SEt amino acid H SH F S-cyclopropyl amino acid H SH F F amino acid H SH F Cl amino acid H SH F Br amino acid H SH F I amino acid acyl SH F H amino acid acyl SH F NH2 amino acid acyl SH F NH-cyclopropyl amino acid acyl SH F NH-methyl amino acid acyl SH F NH-ethyl amino acid acyl SH F NH-acetyl amino acid acyl SH F OH amino acid acyl SH F OMe amino acid acyl SH F OEt amino acid acyl SH F 0-cyclopropyl amino acid acyl SH F 0-acetyl amino acid acyl SH F SH amino acid acyl SH F SMe amino acid acyl SH F SEt amino acid acyl SH F S-cyclopropyl amino acid acyl SH F F amino acid acyl SH F C1 amino acid acyl SH F Br amino acid acyl SH F I R R X X Y acyl H SH Cl H acyl H SH C1 NH2 acyl H SH Cl NH-cyclopropyl acyl H SH C1 NH-methyl acyl H SH C1 NH-ethyl acyl H SH Cl NH-acetyl acyl SH C1 OH acyl SH C1 OMe acyl H SH C1 OEt acyl H SH Cl O-cyclopropyl acyl H SH Cl O-acetyl acyl H SH Cl SH acyl SH C1 SMe acyl SH C1 SEt acyl H SH Cl S-cyclopropyl acyl H SH Cl F acyl H SH C1 C1 acyl H SH Cl Br acyl H SH Cl I acyl acyl SH C1 H acyl acyl SH C1 NH2 acyl acyl SH Cl NH-cyclopropyl acyl ac 1 SH Cl NH-methyl acyl acyl SH C1 NH-ethyl ac 1 ac 1 SH Cl NH-acet 1 acyl acyl SH C1 OH acyl acyl SH C1 OMe acyl acyl SH Cl OEt ac 1 ac 1 SH Cl O-c clo ro 1 acyl acyl SH Cl O-acetyl acyl acyl SH C1 SH acyl acyl SH Cl SMe acyl acyl SH C1 SEt acyl acyl SH Cl S-cyclopro 1 acyl acyl SH Cl F acyl acyl SH C1 C1 acyl acyl SH Cl Br acyl acyl SH C1 acyl amino acid SH C1 H acyl amino acid SH Cl NH2 acyl amino acid SH Cl NH-cyclopropyl acyl amino acid SH Cl NH-methyl acyl amino acid SH Cl-ethyl ac I amino acid SH Cl NH-acetyl acyl amino acid SH C1 OH acyl _amino acid SH C1 OMe acyl amino acid SH C1 OEt R R X X Y acyl amino acid SH Cl O-cyclopropyl acyl amino acid SH Cl O-acetyl acyl amino acid SH Cl SH acyl amino acid SH C1 SMe acyl amino acid SH Cl SEt ac 1 amino acid SH Cl S-c clo ro 1 acyl amino acid SH Cl F acyl amino acid SH C1 C1 acyl amino acid SH Cl Br acyl amino acid SH Cl I H acyl SH C1 H H acyl SH C1 NH2 H ac 1 SH Cl NH-c clo ro 1 H acyl SH C1 NH-methyl H acyl SH Cl NH-ethyl H acyl SH C1 NH-acetyl H acyl SH C1 OH H acyl SH C1 OMe H acyl SH C1 OEt H acyl SH Cl O-cyclopropyl H acyl SH C1 O-acetyl H D acyl SH C1 SH H acyl SH C1 SMe acyl SH C1 SEt H ac 1 SH Cl S-c clo ro 1 H acyl SH C1 F H acyl SH C1 C1 H acyl SH Cl Br H acyl SH Cl I H amino acid SH Cl H H amino acid SH Cl NH2 H amino acid SH Cl NH-c clo ro 1 H amino acid SH Cl NH-methyl H amino acid SH Cl NH-ethyl H amino acid SH Cl NH-acetyl H amino acid SH Cl OH H amino acid SH Cl OMe H amino acid SH Cl OEt H amino acid SH Cl O-cyclopropyl H amino acid SH C1 O-acetyl H amino acid SH Cl SH H amino acid SH Cl SMe H amino acid SH Cl SEt H amino acid SH Cl S-cyclopropyl H amino acid SH Cl F H amino acid SH ci ci H amino acid SH Cl Br R2 R X X Y H amino acid SH Cl I amino acid amino acid SH Cl H amino acid amino acid SH C1 NH2 amino acid amino acid SH Cl NH-cyclopro l amino acid amino acid SH C1 NH-methyl amino acid amino acid SH Cl NH-ethyl amino acid amino acid SH Cl NH-acetyl amino acid amino acid SH Cl OH amino acid amino acid SH C1 OMe amino acid amino acid SH Cl OEt amino acid amino acid SH Cl O-cyclopropyl amino acid amino acid SH C1 O-acetyl amino acid amino acid SH Cl SH amino acid amino acid SH Cl SMe amino acid amino acid SH Cl SEt amino acid amino acid SH Cl S-cyclopropyl amino acid amino acid SH Cl F amino acid amino acid SH Cl Cl amino acid amino acid SH Cl Br amino acid amino acid SH Cl I amino acid H SH C1 H amino acid H SH C1 NH2 amino acid H SH Cl NH-cyclopropyl amino acid H SH C1 NH-methyl amino acid H SH Cl NH-ethyl amino acid H SH Cl NH-acetyl amino acid H SH Cl OH amino acid H SH Cl OMe amino acid H SH Cl OEt amino acid H SH CI O-cyclo ro yl amino acid H SH Cl O-acetyl amino acid H SH Cl SH amino acid H SH C1 SMe amino acid H SH Cl SEt amino acid H SH Cl S-cyclopropyl amino acid _ SH C1 F amino acid SH C1 C1 amino acid H SH Cl Br amino acid H SH Cl I amino acid acyl SH C1 H amino acid acyl SH Cl NH2 amino acid acyl SH Cl NH-cyclopropyl amino acid acyl SH C1 NH-methyl amino acid acyl SH C1 NH-ethyl amino acid acyl SH C1 NH-acetyl amino acid acyl SH C1 OH amino acid acyl SH C1 OMe R R X X Y amino acid acyl SH C1 OEt amino acid Cl 0-cyclopropyl amino acid acyl SH C1 O-acetyl amino acid acyl SH C1 SH amino acid acyl SH C1 SMe amino acid acyl SH Cl SEt amino acid acyl SH Cl S-cyclopropyl amino acid acyl SH C1 F amino acid acyl SH C1 C1 amino acid acyl SH C1 Br amino acid acyl SH C1 I acyl H SH Br H acyl H SH Br NH2 acyl H SH Br NH-cyclopropyl acyl H SH Br NH-methyl acyl H SH Br NH-ethyl acyl H SH Br NH-acetyl acyl H SH Br OH acyl H SH Br OMe acyl H SH Br OEt acyl H SH Br O-cyclopropyl acyl H SH Br O-acetyl acyl H SH Br SH v SH Br SMe acyl H SH Br SEt acyl H SH Br S-cyclopropyi acyl H SH Br F acyl H SH Br Cl acyl H SH Br Br acyl H SH Br I acyl acyl SH Br H acyl acyl SH Br NH2 acyl acyl SH Br NH-cyclopropyl acyl acyl SH Br NH-methyl acyl acyl SH Br NH-ethyl acyl acyl SH Br NH-acetyl acyl acyl SH Br OH acyl acyl SH Br OMe acyl acyl SH Br OEt acyl acyl SH Br O-cyclopropyl acyl acyl SH Br 0-acetyl acyl acyl SH Br SH acyl acyl SH Br SMe acyl acyl SH Br SEt acyl acyl SH Br S-cyclopropyl acyl acyl SH Br F acyl acyl SH Br Cl R2 R3 Xl x2 acyl acyl SH Br Br acyl acyl SH Br I acyl amino acid SH Br H acyl amino acid SH Br NH2 acyl amino acid SH Br NH-cyclopropyl acyl amino acid SH Br NH-methyl acyl amino acid SH Br NH-ethyl acyl amino acid SH Br NH-acetyl acyl amino acid SH Br OH acyl amino acid SH Br OMe acyl amino acid SH Br OEt acyl amino acid SH Br 0-cyclopropyl acyl amino acid SH Br 0-acetyl acyl amino acid SH Br SH acyl amino acid SH Br SMe acyl arnino acid SH Br SEt acyl amino acid SH Br S-cyclopropyl acyl amino acid SH Br F acyl amino acid SH Br Cl acyl arnino acid SH Br Br acyl amino acid SH Br I H acyl SH Br H H acyl SH Br NH2 H acyl SH Br NH-cyclopropyl H acyl SH Br NH-methyl H acyl SH Br NH-ethyl H acyl SH Br NH-acetyl H acyl SH Br OH H acyl SH Br OMe H acyl SH Br OEt acyl SH Br O-cyclopropyl H acyl SH Br 0-acetyl H acyl SH Br SH H acyl SH Br SMe H acyl SH Br SEt H acyl SH Br S-cyclopropyl H acyl SH Br F H acyl SH Br C1 H acyl SH Br Br H acyl SH Br I H amino acid SH Br H H amino acid SH Br NH2 H amino acid SH Br NH-cyclopropyl H amino acid SH Br NH-methyl H amino acid SH Br NH-ethyl H amino acid SH Br NH-acetyl H amino acid SH Br OH R R3 Xl x2 H amino acid SH Br OMe H amino acid SH Br OEt H amino acid SH Br 0-cyclopropyl H amino acid SH Br 0-acetyl H amino acid SH Br SH H amino acid SH Br SMe H amino acid SH Br SEt H amino acid SH Br S-cyclopropyl H amino acid SH Br F H amino acid SH Br Cl H amino acid SH Br Br H amino acid SH Br I amino acid amino acid SH Br H amino acid amino acid SH Br NE amino acid amino acid SH Br NH-cyclopropyl amino acid amino acid SH Br NH-methyl amino acid amino acid SH Br NH-ethyl amino acid amino acid SH Br NH-acetyl # amino acid amino acid SH Br OH amino acid amino acid SH Br OMe amino acid amino acid SH Br OEt amino acid amino acid SH Br 0-cyclopropyl amino acid amino acid SH Br 0-acetyl amino acid amino acid SH Br SH amino acid amino acid SH Br SMe amino acid amino acid SH Br SEt amino acid amino acid SH Br S-cyclopropyl amino acid amino acid SH Br F amino acid amino acid SH Br Cl amino acid amino acid SH Br Br amino acid amino acid SH Br I amino acid H SH Br H amino acid H SH Br NH2 amino acid H SH Br NH-cyclopropyl amino acid H SH Br NH-methyl amino acid H SH Br NH-ethyl amino acid H SH Br NH-acetyl amino acid H SH Br OH amino acid H SH Br OMe amino acid H SH Br OEt amino acid H SH Br 0-cyclopropyl amino acid H SH Br 0-acetyl amino acid H SH Br SH amino acid H SH Br SMe amino acid H SH Br SEt amino acid H SH Br S-cyclopropyl amino acid H SH Br F R2 R3 Xl x2 amino acid H SH Br Cl amino acid H SH Br Br amino acid H SH Br I amino acid acyl SH Br H amino acid acyl SH Br NH2 amino acid acyl SH Br NH-cyclopropyl amino acid acyl SH Br NH-methyl amino acid acyl SH Br NH-ethyl amino acid acyl SH Br NH-acetyl amino acid acyl SH Br OH amino acid acyl SH Br OMe amino acid acyl SH Br OEt amino acid acyl SH Br 0-cyclopropyl amino acid acyl SH Br 0-acetyl amino acid acyl SH Br SH amino acid acyl SH Br SMe amino acid acyl SH Br SEt amino acid ac 1 SH Br S-c clo ro 1 amino acid acyl SH Br F amino acid acyl SH Br Cl amino acid acyl SH Br Br amino acid acyl SH Br I acyl H H SH H ac 1 H H SH NHZ ac 1 H H SH NH-cyclo ro 1 acyl H H SH NH-methyl ac 1 H H SH NH-eth 1 # acyl H H SH NH-acetyl acyl H H SH OH acyl H H SH OMe acyl H H SH OEt acyl H H SH O-cyclopropyl acyl H H SH O-acetyl acyl H H SH SH acyl H H SH SMe acyl H H SH SEt acyl H H SH S-cyclopropyl acyl H H SH F acyl H H SH C1 acyl H H SH Br acyl H H SH I acyl acyl H SH H acyl acyl H SH NH2 acyl acyl H SH NH-cyclopropyl acyl acyl H SH NH-methyl acyl acyl H SH NH-ethyl acyl acyl H SH NH-acetyl R2 R3 X1 X2 acyl acyl H SH OH acyl acyl H SH OMe acyl acyl H SH OEt acyl acyl H SH O-cyclopropyl acyl acyl H SH 0-acetyl acyl acyl H SH SH acyl acyl H SH SMe acyl acyl H SH SEt acyl acyl H SH S-cyclopropyl acyl acyl H SH F acyl acyl H SH C1 acyl acyl H SH Br acyl acyl H SH I acyl amino acid H SH H acyl amino acid H SH NH2 acyl amino acid H SH NH-cyclopropyl acyl amino acid H SH NH-methyl acyl amino acid H SH NH-ethyl acyl amino acid H SH NH-acetyl acyl amino acid H SH OH acyl amino acid H SH OMe acyl amino acid H SH OEt acyl amino acid H SH 0-cyclopropyl acyl amino acid H SH 0-acetyl acyl amino acid H SH SH acyl amino acid H SH SMe acyl amino acid H SH SEt acyl amino acid H SH S-cyclopropyl acyl amino acid H SH F acyl amino acid H SH CI acyl amino acid H SH Br acyl amino acid H SH I H acyl H SH H H acyl H SH NH2 H acyl H SH NH-cyclopropyl H acyl H SH NH-methyl H acyl H SH NH-ethyl H acyl H SH NH-acetyl H acyl H SH OH H acyl H SH OMe H acyl H SH OEt H acyl H SH O-cyclopropyl H acyl H SH 0-acetyl H acyl H SH SH H acyl H SH SMe H acyl H SH SEt H acyl H SH S-cyclopropyl R R X X Y H acyl H SH F H acyl H SH ci H acyl H SH Br H acyl H SH I H amino acid H SH H H amino acid H SH NH2 H amino acid H SH NH-cyclopropyl H amino acid H SH NH-methyl H amino acid H SH NH-ethyl H amino acid H SH NH-acetyl H amino acid H SH OH H amino acid H SH OMe H amino acid H SH OEt H amino acid H SH 0-cyclopropyl H amino acid H SH O-acetyl H amino acid H SH SH H amino acid H SH SMe H amino acid H SH SEt H amino acid H SH S-cyclopropyl H amino acid H SH F H amino acid H SH Cl H amino acid H SH Br H amino acid H SH I amino acid amino acid H SH H amino acid amino acid H SH NH2 amino acid amino acid H SH NH-cyclopropyl amino acid amino acid H SH NH-methyl amino acid amino acid H SH NH-ethyl amino acid amino acid H SH NH-acetyl amino acid amino acid H SH OH amino acid amino acid H SH OMe amino acid amino acid H SH OEt amino acid amino acid H SH 0-cyclopropyl amino acid amino acid H SH 0-acetyl amino acid amino acid H SH SH amino acid amino acid H SH SMe amino acid amino acid H SH SEt amino acid amino acid H SH S-cyclopropyl amino acid amino acid H SH F amino acid amino acid H SH Cl amino acid amino acid H SH Br amino acid amino acid H SH I amino acid H H SH H amino acid H H SH NH2 amino acid H H SH NH-cyclopropyl amino acid H H SH NH-methyl amino acid H H SH NH-ethyl R R X X Y amino acid H H SH NH-acetyl amino acid HUSH OH amino acid H H SH OMe amino acid H H SH OEt amino acid H 0-cyclopropyl amino acid H H SH 0-acetyl amino acid H H SH SH amino acid H H SH SMe amino acid H H SH SEt amino acid H H SH S-cyclopropyl amino acid H H SH F amino acid H H SH Cl amino acid H H SH Br amino acid H H SH I amino acid acyl H SH H amino acid acyl H SH NH2 amino acid acyl H SH NH-cyclopropyl amino acid acyl H SH NH-methyl amino acid acyl H SH NH-ethyl amino acid acyl H SH NH-acetyl amino acid acyl H SH OH amino acid acyl H SH OMe amino acid acyl H SH OEt amino acid acyl H SH 0-cyclopropyl amino acid acyl H SH 0-acetyl amino acid acyl H SH SH amino acid acyl H SH SMe amino acid acyl H SH SEt amino acid acyl H SH S-cyclopropyl amino acid acyl H SH F amino acid acyl H SH Cl amino acid acyl H SH Br amino acid acyl H SH I acyl H F SH H acyl H F SH NH2 acyl H F SH NH-cyclopropyl acyl H F SH NH-methyl acyl H F SH NH-ethyl acyl H F SH NH-acetyl acyl H F SH OH acyl H F SH OMe acyl H F SH OEt acyl H F SH O-cyclo. propyl acyl H F SH 0-acetyl acyl H F SH SH acyl H F SH SMe acyl H F SH SEt R R X X Y acyl H F SH S-cyclopropyl acyl H F SH F acyl H F SH Cl acyl H F SH Br acyl H F SH I acyl acyl F SH H acyl acyl F SH NH2 acyl acyl F SH NH-cyclopropyl acyl acyl F SH NH-methyl acyl acyl F SH NH-ethyl acyl acyl F SH NH-acetyl acyl acyl F SH OH acyl acyl F SH OMe acyl acyl F SH OEt acyl 0-cyclopropyl acyl acyl F SH O-acetyl acyl acyl F SH SH acyl acyl F SH SMe acyl acyl F SH SEt acyl acyl F SH S-cyclopropyl acyl acyl F SH F acyl acyl F SH C1 acyl acyl F SH Br acyl acyl F SH I acyl amino acid F SH H acyl amino acid F SH NH2 acyl amino acid F SH NH-cyclopropyl acyl amino acid F SH NH-methyl acyl amino acid F SH NH-ethyl acyl amino acid F SH NH-acetyl acyl amino acid F SH OH acyl amino acid F SH OMe acyl amino acid F SH OEt acyl amino acid F SH O-cyclopropyl acyl amino acid F SH 0-acetyl acyl amino acid F SH SH acyl amino acid F SH SMe acyl amino acid F SH SEt acyl amino acid F SH S-cyclopropyl acyl amino acid F SH F acyl amino acid F SH Cl acyl amino acid F SH Br acyl amino acid F SH I H acyl F SH H H acyl F SH NH2 H ac 1 F SH NH-c clo ro 1 H acyl F SH NH-methyl R R X X Y H acyl F SH NH-ethyl H acyl F SH NH-acetyl H acyl F SH OH H acyl F SH OMe H acyl F SH OEt H acyl F SH O-cyclopropyl H acyl F SH O-acetyl H acyl F SH SH H acyl F SH SMe H acyl F SH SEt H acyl F SH S-cyclopropyl H acyl F SH F H acyl F SH C1 H acyl F SH Br H acyl F SH I H amino acid F SH H H amino acid F SH NH2 H amino acid F SH NH-cyclopropyl H amino acid F SH NH-methyl H amino acid F SH NH-ethyl H amino acid F SH NH- H amino acid F SH OH H amino acid F SH OMe H amino acid F SH OEt H amino acid F SH O-cyclopropyl H amino acid F SH 0-acetyl H amino acid F SH SH H amino acid F SH SMe H amino acid F SH SEt H amino acid F SH S-cyclopropyl H amino acid F SH F H amino acid F SH Cl H amino acid F SH Br H amino acid F SH I amino acid amino acid F SH H amino acid amino acid F SH NH2 amino acid amino acid F SH NH-cyclopropyl amino acid amino acid F SH NH-methyl amino acid amino acid NH-ethyl amino acid amino acid F SH NH-acetyl amino acid amino acid F SH OH amino acid amino acid F SH OMe amino acid amino acid F SH OEt amino acid amino acid F SH 0-yclopropyl amino acid amino acid F SH 0-acetyl amino acid amino acid F SH SH amino acid amino acid F SH SMe R2 R3 Xl x2 amino acid amino acid F SH SEt amino acid amino acid F SH S-cyclopropyl amino acid amino acid F SH F amino acid amino acid F SH C1 amino acid amino acid F SH Br amino acid amino acid F SH I amino acid H F SH H amino acid H F SH NH2 amino acid H F SH NH-cyclopropyl amino acid H F SH NH-methyl amino acid H F SH NH-ethyl amino acid H F SH NH-acetyl amino acid H F SH OH amino acid H F SH OMe amino acid H F SH OEt amino acid H F SH O-cyclopropyl amino acid H F SH 0-acetyl amino acid H F SH SH amino acid H F SH SMe amino acid H F SH SEt amino acid H F SH S-cyclopropyl amino acid H F SH F amino acid H F SH Cl amino acid H F SH Br amino acid H F SH I amino acid acyl F SH H amino acidacyiJFSH NH2 amino acid acyl F SH NH-cyclopropyl amino acid acyl F SH NH-methyl amino acid acyl F SH NH-ethyl amino acid acyl F SH NH-acetyl amino acid acyl F SH OH amino acid acyl F SH OMe amino acid acyl F SH OEt amino acid acyl F SH O-cyclopropyl amino acid acyl F SH O-acetyl amino acid acyl F SH SH amino acid acyl F SH SMe amino acid acyl F SH SEt amino acid acyl F SH S-cyclopropyl amino acid acyl F SH F amino acid acyl F SH C1 amino acid acyl F SH Br amino acid acyl F SH I I acyl H C1 SH H acyl H C1 SH NH2 acyl H C1 SH NH-cyclopropyl R R X X Y acyl H C1 SH NH-methyl acyl H Cl SH NH-ethyl acyl H C1 SH NH-acetyl acyl H C1 SH OH acyl H C1 SH OMe acyl H C1 SH OEt acyl H Cl SH O-cyclopropyl acyl H C1 SH O-acetyl acyl H Cl SH SH acyl f H Cl SH SMe acyl H Cl SH SEt acyl H Cl SH S-cyclopropyl acyl H C1 SH F * acyl H C1 SH C1 acyl H C1 SH Br acyl H C1 SH I acyl acyl C1 SH H acyl acyl C1 SH NH2 acyl acyl Cl SH NH-cyclopropyl acyl acyl C1 SH NH-methyl acyl acyl C1 SH NH-ethyl acyl acyl C1 SH NH-acetyl acyl acyl C1 SH OH acyl acyl C1 SH OMe acyl acyl C1 SH OEt acyl acyl C1 SH 0-cyclopropyl acyl acyl C1 SH O-acetyl acyl acyl C1 SH SH acyl acyl C1 SH SMe acyl acyl C1 SH SEt acyl acyl C1 SH S-cyclopropyl acyl acyl C1 SH F acyl acyl C1 SH C1 acyl acyl C1 SH Br acyl acyl C1 SH I acyl amino acid Cl SH H acyl amino acid C1 SH NH2 acyl amino acid C1 SH NH-cyclopropyl acyl amino acid C1 SH NH-methyl acyl amino acid C1 SH NH-ethyl acyl amino acid Cl SH NH-acetyl acyl amino acid C1 SH OH acyl amino acid C1 SH OMe acyl amino acid C1 SH OEt acyl amino acid C1 SH 0-cyclopropyl acyl amino acid C1 SH 0-acetyl acyl amino acid C1 SH SH R'xl x2 y acyl amino acid C1 SH SMe acyl amino acid C1 SH SEt acyl amino acid Cl SH S-cyclopropyl acyl amino acid C1 SH F acyl amino acid C1 SH Cl acyl amino acid C1 SH Br acyl amino acid Cl SH I H acyl C1 SH H H acyl C1 SH NH2 H acyl Cl SH NH-cyclopropyl H acyl C1 SH NH-methyl H acyl C1 SH NH-ethyl H acyl C1 SH NH-acetyl H acyl C1 SH OH H acyl C1 SH OMe H ac 1 Cl SH OEt H ac 1 Cl SH O-cyclopropyl H acyl C1 SH 0-acetyl H acyl C1 SH SH H acyl C1 SH SMe H ac 1 Cl SH SEt H acyl C1 SH S-cyclopropyl H acyl C1 SH F H acyl C1 SH C1 H acyl C1 SH Br H acyl C1 SH I Haminoacid Cl SH H H amino acid Cl SH NH2 H amino acid Cl SH NH-cyclopropyl H amino acid Cl SH NH-methyl H amino acid C1 SH NH-ethyl H amino acid Cl SH NH-acetyl H amino acid Cl SH OH H amino acid Cl SH OMe H amino acid Cl SH OEt H amino acid Cl SH 0-cyclopropyl H amino acid Cl SH O-acetyl H amino acid Cl SH SH H amino acid Cl SH SMe H amino acid Cl SH SEt H amino acid Cl SH S-cyclopropyl H amino acid Cl SH F H amino acid Cl SH Cl H amino acid Cl SH Br H amino acid Cl SH I amino acid amino acid C1 SH H amino acid amino acid Cl SH NH2 R R X X Y amino acid amino acid Cl SH NH-c clo ro yl amino acid amino acid Cl SH NH-methyl amino acid amino acid Cl SH NH-ethyl amino acid amino acid Cl SH NH-acetyl amino acid amino acid Cl SH OH amino acid amino acid Cl SH OMe amino acid amino acid Cl SH OEt amino acid amino acid Cl SH O-cyclopropyl amino acid amino acid Cl SH O-acetyl amino acid amino acid C1 SH SH amino acid amino acid Cl SH SMe amino acid amino acid Cl SH SEt amino acid amino acid Cl SH S-cyclopropyl amino acid amino acid Cl SH F amino acid amino acid Cl SH Cl amino acid amino acid Cl SH Br amino acid amino acid Cl SH I amino acid H C1 SH H amino acid H C1 SH NH2 amino acid H Cl SH NH-cyclopropyl amino acid H C1 SH NH-methyl amino acid H C1 SH NH-ethyl amino acid H C1 SH NH-acetyl amino acid H C1 SH OH amino acid H C1 SH OMe amino acid H C1 SH OEt amine acid H Cl SH 0-cyclopropyl amino acid H C1 SH O-acetyl amino acid H C1 SH SH amino acid C1 SH SMe amino acid H C1 SH SEt amino acid H Cl SH S-cyclopropyl amino acid H C1 SH F amino acid H ci SH ci amino acid H C1 SH Br amino acid H C1 SH I amino acid acyl Cl SH H amino acid acyl Cl SH NH2 amino acid acyl C1 SH NH-cyclopropyl amino acid acyl C1 SH NH-methyl amino acid acyl C1 SH NH-ethyl amino acid acyl C1 SH NH-acetyl amino acid acyl C1 SH OH amino acid acyl C1 SH OMe amino acid acyl C1 SH OEt amino acid acyl C1 SH 0-cyclopropyl amino acid acyl Cl SH O-acetyl R2 R3 Xl x2 amino acid acyl C1 SH SH amino acid acyl C1 SH SMe amino acid acyl Cl SH SEt amino acid acyl Cl SH S-cyclopropyl amino acid acyl C1 SH F amino acid acyl C1 SH Cl amino acid acyl C1 SH Br amino acid acyl C1 SH I acyl H Br SH H acyl H Br SH NH2 acyl H Br SH NH-cyclopropyl acyl H Br SH NH-methyl acyl H Br SH NH-ethyl acyl H Br SH NH-acetyl acyl H Br SH OH acyl H Br SH OMe acyl H Br SH OEt acyl H Br SH 0-cyclopropyl acyl H Br SH 0-acetyl acyl H Br SH SH acyl H Br SH SMe acyl H Br SH SEt acyl H Br SH S-cyclopropyl acyl H Br SH F acyl H Br SH C1 acyl H Br SH Br acyl H Br SH I acyl acyl Br SH H acyl acyl Br SH NH2 acyl acyl Br SH NH-cyclopropyl acyl acyl Br SH NH-methyl acyl acyl Br SH NH-ethyl acyl acyl Br SH NH-acetyl acyl acyl Br SH OH acyl acyl Br SH OMe acyl acyl Br SH OEt acyl acyl Br SH O-cyclopropyl acyl acyl Br SH 0-acetyl acyl acyl Br SH SH acyl acyl Br SH SMe acyl acyl Br SH SEt acyl acyl Br SH S-cyclopropyl acyl acyl Br SH F acyl acyl Br SH Cl acyl acyl Br SH Br acyl acyl Br SH I acyl amino acid Br SH H R R X'X Y acyl amino acid Br SH NH2 acyl amino acid Br SH NH-cyclopropyl acyl amino acid Br SH NH-methyl acyl amino acid Br SH NH-ethyl S acyl amino acid Br SH NH-acetyl acyl amino acid Br SH OH acyl amino acid Br SH OMe acyl amino acid Br SH OEt acyl amino acid Br SH 0-cyclopropyl acyl amino acid Br SH O-acetyl acyl amino acid Br SH SH acyl amino acid Br SH SMe acyl amino acid Br SH SEt acyl amino acid Br SH S-cyclopropyl acyl amino acid Br SH F acyl amino acid Br SH Cl acyl amino acid Br SH Br acyl amino acid Br SH I H acyl Br SH H H acyl Br SH NH2 H acyl Br SH NH-cyclopropyl H acyl Br SH NH-methyl H acyl Br SH NH-ethyl acyl Br SH NH-acetyl H acyl Br SH OH H acyl Br SH OMe H acyl Br SH OEt H acyl Br SH 0-cyclopropyl H acyl Br SH 0-acetyl H acyl Br SH SH H acyl Br SH SMe H acyl Br SH SEt H acyl Br SH S-cyclopropyl H acyl Br SH F H acyl Br SH Cl H acyl Br SH Br H acyl Br SH H amino acid Br SH H H amino acid Br SH NH2 H amino acid Br SH NH-cyclopropyl H amino acid Br SH NH-methyl H amino acid Br SH NH-ethyl H amino acid Br SH NH-acetyl H amino acid Br SH OH H amino acid Br SH OMe H amino acid Br SH OEt H amino acid Br SH 0-cyclopropyl R R'X X Y H amino acid Br SH 0-acetyl H amino acid Br SH SH H amino acid Br SH SMe H amino acid Br SH SEt H amino acid Br SH S-cyclopropyl H amino acid Br SH F H amino acid Br SH Cl H amino acid Br SH Br H amino acid Br SH I amino acid amino acid Br SH H amino acid amino acid Br SH NH2 amino acid amino acid Br SH NH-cyclopropyl amino acid amino acid Br SH NH-methyl amino acid amino acid Br SH NH-ethyl amino acid amino acid Br SH NH-acetyl amino acid amino acid Br SH OH amino acid amino acid Br SH OMe amino acid amino acid Br SH OEt amino acid amino acid Br SH 0-cyclopropyl amino acid amino acid Br SH 0-acetyl amino acid amino acid Br SH SH amino acid amino acid Br SH SMe amino acid amino acid Br SH SEt amino acid amino acid Br SH S-cyclopropyl amino acid amino acid Br SH F amino acid amino acid Br SH Cl amino acid amino acid Br SH Br amino acid amino acid Br SH I amino acid H Br SH H amino acid H Br SH NH2 amino acid H Br SH NH-cyclopropyl amino acid H Br SH NH-methyl amino acid H Br SH NH-ethyl amino acid H Br SH NH-acetyl amino acid H Br SH OH amino acid H Br SH OMe amino acid H Br SH OEt amino acid H Br SH 0-cyclopropyl amino acid H Br SH 0-acetyl amino acid H Br SH SH amino acid H Br SH SMe amino acid H Br SH SEt amino acid H Br SH S-cyclopropyl amino acid H Br SH F amino acid H Br SH CI amino acid H Br SH Br amino acid H Br SH I R R X X _Y amino acid acyl Br SH H amino acid acyl Br SH NH2 amino acid acyl Br SH NH-cyclopropyl amino acid acyl Br SH NH-methyl amino acid acyl Br SH NH-ethyl amino acid acyl Br SH NH-acetyl amino acid acyl Br SH OH amino acid acyl Br SH OMe amino acid acyl Br SH OEt amino acid acyl Br SH 0-cyclopropyl amino acid acyl Br SH 0-acetyl amino acid acyl Br SH SH amino acid acyl Br SH SMe amino acid acyl Br SH SEt amino acid acyl Br SH S-cyclopropyl amino acid acyl Br SH F amino acid acyl Br SH ci amino acid acyl Br SH Br amino acid acyl Br SH I acyl H F F H acyl H F F NH2 acyl H F F NH-cyclopropyl acyl H F F NH-methyl acyl H F F NH-ethyl acyl H F F NH-acetyl acyl H F F OH acyl H F F OMe acyl H F F OEt acyl H F F O-cyclopropyl acyl H F F O-acetyl acyl H F F SH acyl H F F SMe acyl H F F SEt acyl H F F S-cyclopropyl acyl H F F F acyl H F F C1 acyl H F F Br acyl H F F acyl acyl F F H acyl acyl F F NH2 acyl acyl F F NH-cyclopropyl acyl acyl F F NH-methyl acyl acyl F F NH-ethyl acyl acyl F F NH-acetyl acyl acy F F OH acyl acyl F F OMe acyl acyl F F OEt R w y acyl acyl F F 0-cyclopropyl acyl acyl F F 0-acetyl acyl acyl F F SH acyl acyl F F SMe acyl acyl F F SEt acyl acyl F F S-cyclopropyl acyl acyl F F F acyl acyl F F C1 acyl acyl F F Br acyl acyl F F I acyl amino acid F F H acyl amino acid F F NH2 acyl amino acid F F NH-cyclopropyl acyl amino acid F F | NH-methyl acyl amino acid F F NH-ethyl acyl amino acid F F NH-acetyl acyl amino acid F F OH acyl amino acid F F OMe acyl amino acid F F OEt ac 1 amino acid F F O-c clo ro 1 acyl amino acid F F O-acetyl acyl amino acid F SH acyl amino acid F F SMe acyl amino acid F F SEt ac 1 amino acid F F S-c clo ro 1 acyl amino acid F F F acyl amino acid F F C1 acyl amino acid F F Br acyl amino acid F F I H acyl F F H H acyl F F NH2 H acy F F NH-cyclopropyl H acyl F F NH-methyl H acyl F F NH-ethyl H acyl F F NH-acetyl H acyl F F OH H acyl F F OMe H acyl F F OEt H acyl F F 0-cyclopropyl H acyl F F 0-acetyl H _ acyl F F SH H acyl F F SMe H acyl F F SEt H acyl F F S-cyclopropyl H acyl F F F H acyl F F ci H acyl F F Br JHacyiJFFJ8r R R X X Y H acyl F F I H amino acid F F H H amino acid F F NH2 H amino acid F F NH-cyclopropyl H amino acid F F NH-methyl H amino acid F F NH-ethyl H amino acid F F NH-acetyl H amino acid F F OH H amino acid F F OMe H amino acid F F OEt H amino acid F F O-c clo ro 1 H amino acid F F O-acetyl H amino acid F F SH H amino acid F F SMe H amino acid F F SEt H amino acid F F S-cyclopropyl H amino acid F F F H amino acid F F Cl H amino acid F F Br H amino acid F F I amino acid amino acid F F H amino acid amino acid F F NH2 amino acid amino acid F F NH-cyclopropyl amino acid amino acid F F NH-methyl amino acid amino acid F F NH-ethyl amino acid amino acid F F NH-acetyl amino acid amino acid F F OH amino acid amino acid F F OMe amino acid amino acid F F OEt amino acid amino acid F F O-cyclopropyl amino acid amino acid F F 0-acetyl amino acid amino acid F F SH amino acid amino acid F F SMe amino acid amino acid F F SEt amino acid amino acid F F S-cyclopropyl amino acid amino acid F F F amino acid amino acid F F Cl amino acid amino acid F F Br amino acid amino acid F F I amino acid H F F H amino acid H F F amino acid H F F NH-cyclopropyl amino acid H F F NH-methyl amino acid H F F NH-ethyl amino acid H F F NH-acetyl amino acid H F F OH amino acid H F F OMe R R X X Y amino acid H F F OEt amino acid H F F 0-cyclopropyl amino acid H F F O-acetyl amino acid F F SH amino acid H F F SMe amino acid F F SEt amino acid H F F S-cyclopropyl amino acid H F F F amino acid H F F C1 amino acid H F F Br amino acid H F F I amino acid acyl F F amino acid acyl F F NH2- amino acid acyl F F NH-cyclopropyl amino acid acyl F F NH-methyl amino acid acyl F F NH-ethyl amino acid acyl F F NH-acetyl amino acid acyl F F OH amino acid acyl F F OMe amino acid acyl F F OEt amino acid acyl F F 0-cyclopropyl amino acid acyl F F O-acetyl amino acid acyl F F SH amino acid acyl F F SMe amino acid acyl F F SEt amino acid acyl F S-cyclopropyl amino acid acyl F F F amino acid acyl F F C1 amino acid acyl F F Br amino acid acyl F F I acyl H C1 C1 H acyl H C1 C1 NH2 ac 1 H Cl Cl NH-c clo ro 1 acyl H C1 C1 NH-methyl acyl H C1 C1 NH-ethyl acyl H C1 C1 NH-acetyl acyl H C1 C1 OH acyl H C1 C1 OMe acyl H C1 C1 OEt acyl H C1 C1 O-cyclopropyl acyl H C1 C1 O-acetyl acyl H C1 C1 SH acyl H _ C1 C1 SMe acyl H C1 C1 SEt acyl H Cl Cl S-cyclopropyl ac 1 H CI Cl F acyl H C1 C1 C1 R R X X Y __ acyl H C1 C1 Br acyiHC1Jd [ acyl H C1 C1 acyl acyl ci ci H acyl acyl C1 C1 NH2 acyl acyl Cl Cl NH-cyclopropyl acyl acyl C1 C1 NH-methyl acyl acyl C1 C1 NH-ethyl acyl acyl C1 C1 NH-acetyl acyl acyl C1 C1 OH acyl acyl C1 C1 OMe acyl acyl C1 C1 OEt acyl acyl ci ci 0-cyclopropyl acyl acyl C1 C1 O-acetyl acyl acyl C1 C1 SH acyl acyl C1 C1 SMe acyl acyl C1 C1 SEt acyl acyl C1 C1 S-cyclopropyl acyl acyl C1 C1 F acyl acyl C1 C1 C1'- acyl acyl C1 C1 Br acyl acyl C1 C1 I acyl amino acid C1 C1 H acyl amino acid C1 C1 NH2 acyl amino acid Cl Cl NH-cyclopropyl acyl amino acid C1 C1 NH-methyl acyl amino acid Cl C1 NH-ethyl acyl amino acid C1 C1 NH-acetyl acyl amino acid Cl Cl OH acyl amino acid Cl Cl OMe acyl amino acid Cl Cl OEt ac 1 amino acid Cl Cl O-c clo ro 1 acyl amino acid C1 C1 O-acetyl acyl amino acid C1 C1 SH acyl amino acid Cl Cl SMe acyl amino acid Cl Cl SEt acyl amino acid C1 C1 S-cyclopropyl acyl amino acid ci ci F acyl amino acid Cl Cl Cl acyl amino acid C1 C1 Br acyl amino acid C1 C1 I H acyl Cl Cl H H acyl C1 C1 NH2 H acyl C1 C1 NH-cyclopropyl H acyl C1 C1 NH-methyl H acyl C1 C1 NH-ethyl H acyl C1 C1 NH-acetyl H acyl C1 C1 OH R t X X Y acyl C1 C1 OMe H acyl C1 C1 OEt H acyl Cl Cl O-cyclopropyl H acyl Cl Cl O-acetyl H acyl Cl C1 SH H acyl C1 C1 SMe H acyl C1 C1 SEt H acyl C1 C1 S-cyclo ropyl H acyl Cl C1 P,. H acyl C1 C1 C1 H acyl Cl C1 Br H acyl C1 C1 I H amino acid Cl Cl H H amino acid Cl Cl NH2 H amino acid Cl Cl NH-cyclopropyl H amino acid CI Cl NH-methyl H amino acid Cl Cl NH-ethyl H amino acid Cl Cl NH-acetyl H amino acid Cl Cl OH H amino acid Cl Cl OMe H amino acid Cl Cl OEt H amino acid Cl Cl O-cyclopropyl H amino acid C1 C1 O-acetyl H amino acid CI Cl SH H amino acid Cl Cl SMe H amino acid CI Cl SEt H amino acid Cl Cl S-cyclopropyl H amino acid Cl Cl F H amino acid Cl Cl Cl H amino acid Cl CI Br H amino acid Cl Cl I amino acid amino acid Cl Cl H amino acid amino acid C1 C1 NH2 amino acid amino acid C1 C1 NH-cyclopropyl amino acid amino acid Cl Cl NH-methyl amino acid amino acid C1 C1 NH-ethyl amino acid amino acid C1 C1 NH-acetyl amino acid amino acid Cl Cl OH amino acid amino acid Cl Cl OMe amino acid amino acid Cl Cl OEt amino acid amino acid ci ci 0-cyclopropyl amino acid amino acid C1 C1 O-acetyl amino acid amino acid Cl Cl SH amino acid amino acid Cl Cl SMe amino acid amino acid Cl Cl SEt amino acid amino acid Cl Cl S-cyclopropyl amino acid amino acid Cl Cl F R R X X Y amino acid amino acid Cl Cl Cl amino acid amino acid Cl Cl Br amino acid amino acid Cl Cl I amino acid H Cl Cl H amino acid H Cl C1 NH2 amino acid H Cl Cl NH-cyclopropyl amino acid H Cl Cl NH-methyl amino acid H Cl Cl NH-ethyl amino acid H Cl Cl NH-acetyl amino acid H Cl Cl OH amino acid H Cl Cl OMe amino acid H Cl Cl OEt amino acid H Cl Cl O-cyclopropyl amino acidHCl Cl 0-acetyl amino acid H Cl Cl SH amino acid H Cl Cl SMe amino acid H Cl Cl SEt amino acid H Cl Cl S-cyclopropyl amino acid H Cl Cl F amino acid H C1 C1 C1 amino acid H Cl Cl Br amino acid H Cl Cl I amino acid acyl C1 C1 H amino acid acyl C1 Cl NH2 amino acid acyl Cl Cl NH-cyclopropyl amino acid acyl Cl NH-methyl amino acid acyl Cl Cl NH-ethyl amino acid acyl Cl C1 NH-acetyl amino acid acyl C1 C1 OH amino acid acyl C1 C1 OMe amino acid acyl C1 C1 OEt amino acid Cl 0-cyclopropyl amino acid ac 1 Cl Cl O-acet 1 amino acid acyl C1 Cl SH amino acid acyl C1 C1 SMe amino acid acyl C1 C1 L SEt amino acid ac 1 Cl Cl S-c clo ro 1 amino acid _ acyl C1 C1 F amino acid acyl C1 C1 C1 amino acid acyl Cl C1 Br amino acid acyl C1 C1 I acyl H OH OH H acyl H OH OH NH2 acyl H OH OH NH-cyclopropyl acyl H OH OH NH-methyl S acyl H OH OH NH-ethyl acyl H OH OH NH-acetyl R R X X Y acyl H OH OH OH acyl H OH OH OMe acyl H OH OH OEt acyl H OH 0-cyclopropyl acyl H OH OH 0-acetyl acyl H OH OH SH acyl H OH OH SMe acyl H OH OH SEt acyl H OH OH S-cyclopropyl acyl H OH OH F acyl H OH OH ci acyl H OH OH Br acyl H OH OH I acyl acyl OH OH H acyl acyl OH OH NH2 acyl acyl OH OH NH-cyclopropyl acyl acyl OH OH NH-methyl acyl acyl OH OH NH-ethyl acyl acyl OH OH NH-acetyl acyl acyl OH OH OH acyl acyl OH OH OMe acyl acyl OH OH OEt acyl acyl OH 0-cyclopropyl acyl acyl OH OH 0-acetyl acyl acyl OH OH SH acyl acyl OH OH SMe acyl acyl OH OH SEt acyl acyl OH OH S-cyclopropyl acyl acyl OH OH F acyl acyl OH OH Cl acyl acyl OH OH Br acyl acyl OH OH I acyl amino acid OH OH H acyl amino acid OH OH NH2 acyl amino acid OH OH NH-cyclopropyl acyl amino acid OH OH NH-methyl acyl amino acid OH OH NH-ethyl acyl amino acid OH OH NH-acetyl acyl amino acid OH OH OH acyl amino acid OH OH OMe acyl amino acid OH OH OEt acyl amino acid OH OH 0-cyclopropyl acyl amino acid OH OH 0-acetyl acyl amino acid OH OH SH acyl amino acid OH OH SMe acyl amino acid OH OH SEt acyl amino acid OH OH S-cyclopropy R R X X Y acyl amino acid OH OH F acyl amino acid OH OH Cl acyl amino acid OH OH Br acyl amino acid OH OH I H acyl OH OH H H acyl OH OH NH2 H acyl OH OH NH-cyclopropyl H acyl OH OH NH-methyl H acyl OH OH NH-ethyl H acyl OH OH NH-acetyl H acyl OH OH OH H acyl OH OH OMe H acyl OH OH OEt H acyl OH OH 0-cyclopropyl H acyl OH OH O-acetyl H acyl OH OH SH H acyl OH OH SMe H acyl OH OH SEt H acyl OH OH S-cyclopropyl H acyl OH OH F H acyl OH OH ci H acyl OH OH Br H acyl OH OH I H amino acid OH OH H H amino acid, OH OH NH2 H amino acid OH OH NH-cyclopropyl H amino acid OH OH NH-methyl H amino acid OH OH NH-ethyl H amino acid OH OH NH-acetyl H amino acid OH OH OH H amino acid OH OH OMe H amino acid OH OH OEt H amino acid OH OH O-cyclopropyl H amino acid OH OH 0-acetyl H amino acid OH OH SH H amino acid OH OH SMe H amino acid OH OH SEt H amino acid OH OH S-c clo ro 1 H amino acid OH OH F H amino acid OH OH Cl H amino acid OH OH Br H amino acid OH OH I amino acid amino acid OH OH H amino acid amino acid OH OH NHz amino acid amino acid OH OH NH-cvoloDroovl amino acid amino acid OH OH NH-methyl amino acid amino acid OH OH NH-ethyl R 2 R3 xl x2 y amino acid amino acid OH OH NH-acetyl amino acid amino acid OH OH OH amino acid amino acid OH OH OMe amino acid amino acid OH OH OEt amino acid amino acid OH OH 0-cyclopropyl amino acid amino acid OH OH 0-acetyl amino acid amino acid OH OH SH amino acid amino acid OH OH SMe amino acid amino acid OH OH SEt amino acid amino acid OH OH S-cyclopropyl amino acid amino acid OH OH F amino acid amino acid OH OH Cl amino acid amino acid OH OH Br amino acid amino acid OH OH I amino acid H OH OH H amino acid H OH OH NH2 amino acid H OH OH NH-cyclopropyl amino acid H OH OH NH-methyl amino acid H OH OH NH-ethyl amino acid H OH OH NH-acetyl amino acid OH OH OH amino acid H OH OH OMe amino acid H OH OH OEt amino acid H OH OH 0-cyclopropyl amino acid H OH OH 0-acetyl amino acid H OH OH SH amino acid H OH OH SMe amino acid H OH OH SEt amino acid H OH OH S-cyclopropyl amino acid H OH OH F amino acid H OH OH Cl amino acid H OH OH Br amino acid H OH OH I amino acid acyl OH OH H amino acid acyl OH OH NH2 amino acid acyl OH OH NH-cyclopropyl amino acid acyl OH OH NH-methyl amino acid acyl OH OH NH-ethyl amino acid acyl OH OH NH-acetyl amino acid acyl OH OH OH amino acid acyl OH OH OMe amino acid acyl OH OH OEt amino acid acyl OH OH 0-cyclopropyl amino acid acyl OH OH 0-acetyl amino acid acyl OH OH SH amino acid acyl OH OH SMe amino acid acyl OH OH SEt R R X X Y amino acid acyl OH OH S-cyclopropyl amino acid acyl OH OH F amino acid acyl OH OH Cl amino acid acyl OH OH Br amino acid acyl OH OH I acyl H SH SH H acyl H SH SH NH2 acyl SH SH NH-cyclopropyl acyl H SH SH NH-methyl acyl H SH SH NH-ethyl acyl SH SH NH-acetyl acyl H SH SH OH S acyl H SH SH OMe acyl H SH SH OEt acyl H SH SH 0-cyclopropyl acyl H SH SH 0-acetyl acyl H SH SH SH acyl H SH SH SMe acyl H SH SH SEt acyl H SH SH S-cyclopropyl acyl H SH SH F acyl H SH SH Cl acyl H SH SH Br acyl H SH SH I S acyl acyl SH SH H acyl acyl SH SH NH2 acyl acyl SH SH NH-cyclopropyl acyl acyl SH SH NH-methyl acyl acyl SH SH NH-ethyl acyl acyl SH SH NH-acetyl acyl acyl SH SH OH acyl acyl SH SH OMe acyl acyl SH SH OEt acyl acyl SH 0-cyclopropyl acyl acyl SH SH 0-acetyl acyl acyl SH SH SH acyl acyl SH SH SMe acyl acyl SH SH SEt acyl acyl SH SH S-cycloprop yl acyl acyl SH SH F acyl acyl SH SH Cl acyl acyl SH SH Br acyl acyl SH SH I acyl amino acid SH SH H acyl amino acid SH SH NH2 acyl amino acid SH SH NH-cyclopropyl acyl amino acid SH SH NH-methyl R R3 Xl x2 acyl amino acid SH SH NH-ethyl acyl amino acid SH SH NH-acetyl acyl amino acid SH SH OH acyl amino acid SH SH OMe acyl amino acid SH SH OEt acyl amino acid SH SH 0-cyclopropyl acyl amino acid SH SH 0-acetyl acyl amino acid SH SH SH acyl amino acid SH SH SMe acyl amino acid SH SH SEt acyl amino acid SH SH S-cyclopropyl acyl amino acid SH SH F acyl amino acid SH SH Cl acyl amino acid SH SH Br acyl amino acid SH SH I H acyl SH SH H H acyl SH SH NH2 H acyl SH SH NH-cyclopropyl H acyl SH SH NH-methyl H acyl SH SH NH-ethyl H acyl SH SH NH-acetyl H acyl SH SH OH H acyl SH SH OMe H acyl SH SH OEt H acyl SH 0-cyclopropyl H acyl SH SH 0-acetyl H acyl SH SH SH H acyl SH SH SMe H acyl SH SH SEt H acyl SH SH S-cyclopropyl H acyl SH SH F H acyl SH SH ci H acyl SH SH Br H acyl SH SH I H amino acid SH SH H H amino acid SH SH NH2 H amino acid SH SH NH-cycloprop H amino acid SH SH NH-methyl H amino acid SH SH NH-ethyl H amino acid SH SH NH-acetyl H amino acid SH SH OH H amino acid SH SH OMe H amino acid SH SH OEt H amino acid SH SH 0-cyclopropyl H amino acid SH SH 0-acetyl H amino acid SH SH SH H amino acid SH SH SMe R R X X Y H amino acid SH SH SEt H amino acid SH SH S-cyclopropyl H amino acid SH SH F H amino acid SH SH Cl H amino acid SH SH Br H amino acid SH SH I amino acid amino acid SH SH H amino acid amino acid SH SH NH2 amino acid amino acid SH SH NH-cyclopropyl amino acid amino acid SH SH NH-methyl amino acid amino acid SH SH NH-ethyl amino acid amino acid SH SH NH-acetyl amino acid amino acid SH SH OH amino acid amino acid SH SH OMe amino acid amino acid SH SH OEt amino acid amino acid SH SH 0-cyclopropyl amino acid amino acid SH SH 0-acetyl amino acid amino acid SH SH SH amino acid amino acid SH SH SMe amino acid amino acid SH SH SEt amino acid amino acid SH SH S-cyclopropyl amino acid amino acid SH SH F amino acid amino acid SH SH Cl amino acid amino acid SH SH Br amino acid amino acid. SH SH I amino acid H SH SH H amino acid H SH SH NH2 amino acid H SH SH NH-cyclopropyl J r v amino acid H SH SH NH-methyl amino acid H SH SH NH-ethyl amino acid H SH SH NH-acetyl amino acid H SH SH OH amino acid H SH SH OMe amino acid H SH SH OEt amino acid H SH SH 0-cyclopropyl amino acid H SH SH 0-acetyl amino acid H SH SH SH amino acid H SH SH SMe amino acid H SH SH SEt amino acid H SH SH S-cyclopropyl amino acid H SH SH F amino acid H SH SH Cl amino acid H SH SH Br amino acid H SH SH I amino acid acyl SH SH H amino acid acyl SH SH NH2 amino acid acyl SH SH NH-cyclopropyl R2 R3 Xl XZ amino acid acyl SH SH NH-methyl amino acid acyl SH SH NH-ethyl amino acid acyl SH SH NH-acetyl amino acid acyl SH SH OH amino acid acyl SH SH OMe amino acid acyl SH SH OEt amino acid acyl SH SH O-cyclopropyl amino acid acyl SH SH 0-acetyl amino acid acyl SH SH SH amino acid acyl SH SH SMe amino acid acyl SH SH SEt amino acid acyl SH SH S-cyclopropyl amino acid acyl SH SH F amino acid acyl SH SH Cl amino acid acyl SH SH Br amino acid acyl SH SH I acyl H I I H Table 2 RZ R3 Xl acyl H H H acyl H H NH2 acyl H H NH-cyclopropyl acyl H H NH-methyl acyl H H NH-ethyl acyl H H NH-acetyl acyl H H OH acyl H H OMe acyl H H OEt acyl H H O-c clo ro 1 acyl H H 0-acetyl acyl H H SH acyl H H SMe acyl H H SEt acyl H H S-cyclopropyl acyl H H F acyl H H C1 acyl H H Br acyl H H I acyl acyl H H acyl acyl H NH2 acyl ac 1 H NH-cyclo ro yl acyl acyl H NH-methyl acyl acyl H NH-ethyl acyl acyl H NH-acetyl acyl acyl H OH acyl acyl H OMe acyl acyl H OEt acyl 0-cyclopropyl acyl acyl H O-acetyl acyl acyl H SH acyl acyl H SMe acyl acyl H SEt acyl acyl S-cyclopropyl acyl acyl H F acyl acyl H Cl acyl acyl H Br acyl acyl H I acyl amino acid H H acyl amino acid H NH2 acyl amino acid H NH-cyclopropyl acyl amino acid H NH-methyl R R3 Xl acyl amino acid H NH-ethyl acyl amino acid H NH-acetyl acyl amino acid H OH acyl amino acid H OMe acyl amino acid H OEt acyl amino acid H 0-cyclopropyl acyl amino acid H 0-acetyl acyl amino acid H SH acyl amino acid H SMe acyl amino acid H SEt acyl amino acid H S-cyclopropyl acyl amino acid H F acyl amino acid H Cl acyl amino acid H Br acyl amino acid H I H acyl H H H acyl H NH2 H acyl H NH-cyclopropyl H acyl H NH-methyl H acyl H NH-ethyl H acyl H NH-acetyl H acyl H OH H acyl H OMe H acyl H OEt H acyl H O-cyclopropyl H acyl H O-acetyl H acyl H SH H acyl H SMe H acyl H SEt H acyl H S-cyclopropyl H acyl H F acyl H C1 H acyl H Br H acyl H I H amino acid H H H amino acid H NH2 H amino acid H NH-cyclopropyl H amino acid H NH-methyl H amino acid H NH-ethyl H amino acid H NH-acetyl H amino acid H OH H amino acid H OMe H amino acid H OEt H amino acid H O-cyclopropyl RZ R 3 xl y H amino acid H O-acetyl H amino acid H SH H amino acid H SMe H amino acid H SEt H amino acid H S-cyclopropyl H amino acid H F H amino acid H Cl H amino acid H Br H amino acid H I amino acid amino acid H H amino acid amino acid H NH2 amino acid amino acid H NH-cyclopropyl amino acid amino acid H NH-methyl amino acid amino acid H NH-ethyl amino acid amino acid H NH-acetyl amino acid amino acid OH amino acid amino acid H OMe amino acid amino acid H OEt amino acid amino acid H 0-cyclopropyl amino acid amino acid H O-acetyl amino acid amino acid H SH amino acid amino acid H SMe amino acid amino acid H SEt amino acid amino acid H S-cyclopropyl amino acid amino acid H F amino acid amino acid C1 amino acid amino acid H Br amino acid amino acid H I amino acid H H H amino acid H H NH2 amino acid H H NH-cyclopropyl amino acid H H NH-methyl amino acid H H NH-ethyl amino acid H H NH-acetyl amino acid H H OH amino acid H H OMe amino acid H H OEt amino acid H H 0-cyclopropyl amino acid H H O-acetyl amino acid H H SH amino acid H H SMe amino acid H H SEt amino acid H H S-cyclopropyl amino acld H H F R R X Y amino acid H H Cl amino acid H H Br amino acid H H I amino acid acyl H H amino acid acyl H NH2 amino acid acyl H NH-cyclopropyl amino acid acyl H NH-methyl amino acid acyl H NH-ethyl amino acid acyl H NH-acetyl amino acid acyl H OH amino acid acyl H OMe amino acid acyl H OEt amino acid acyl H 0-cyclopropyl amino acid acyl H O-acetyl amino acid acyl H SH amino acid acyl H SMe amino acid acyl H SEt amino acid acyl H S-cyclopropyl amino acid acyl H F f amino acid acyl H C1 amino acid acyl H Br amino acid acyl H I acyl H SH H acyl H SH NH2 acyl H SH NH-cyclopropyl acyl H SH NH-methyl acyl H SH NH-ethyl acyl H SH NH-acetyl acyl H SH OH acyl H SH OMe acyl H SH OEt acyl H SH 0-cyclopropyl acyl H SH O-acetyl acyl H SH SH acyl H SH SMe acyl H SH SEt acyl H SH S-cyclopropyl acyl H SH F acyl H SH Cl acyl H SH Br acyl H SH I acyl acyl SH H acyl acyl SH NH2 acyl acyl SH NH-cyclopropyl R2 R 3 xl y acyl acyl SH NH-methyl acyl acyl SH NH-ethyl acyl acyl SH NH-acetyl acyl acyl SH OH t acyl acyl SH OMe acyl acyl SH OEt acyl acyl SH O-cyclopropyl acyl acyl SH 0-acetyl acyl acyl SH SH acyl acyl SH SMe acyl acyl SH SEt acyl acyl SH S-cyclopropyl acyl acyl SH F acyl acyl SH Cl acyl acyl SH Br acyl acyl SH I acyl amino acid SH H acyl amino acid SH NH2 acyl amino acid SH NH-cyclopropyl acyl amino acid SH NH-methyl acyl amino acid SH NH-ethyl acyl amino acid SH NH-acetyl acyl amino acid SH OH acyl amino acid SH OMe acyl amino acid SH OEt acyl amino acid SH O-cyclopropyl ac 1 amino acid SH O-acetyl Y acyl amino acid SH SH acyl amino acid SH SMe acyl amino acid SH SEt acyl amino acid SH S-cyclopropyl acyl amino acid SH F acyl amino acid SH C1 acyl amino acid SH Br acyl amino acid SH I H acyl SH H H acyl SH NH2 H acyl SH NH-cyclopropyl H acyl SH NH-methyl H acyl SH NH-ethyl H acyl SH NH-acetyl H acyl SH OH H acyl SH OMe H acyl SH OEt R ~ R3 Xl H acyl SH O-cyclopropyl H acyl SH 0-acetyl H acyl SH SH H acyl SH SMe H acyl SH SEt H acyl SH S-cyclopropyl H acyl SH F H acyl SH Cl H acyl SH Br H acyl SH I H amino acid SH H H amino acid SH NH2 H amino acid SH NH-cyclopropyl H amino acid SH NH-methyl H amino acid SH NH-ethyl H amino acid SH NH-acetyl H amino acid SH OH H amino acid SH OMe H amino acid SH OEt H amino acid SH O-cyclopropyl H amino acid SH 0-acetyl H amino acid SH SH H amino acid SH SMe H amino acid SH SEt H amino acid SH S-cyclopropyl H amino acid SH F H amino acid SH Cl H amino acid SH Br H amino acid SH I amino acid amino acid SH H amino acid amino acid SH NH2 amino acid amino acid SH NH-cyclopropyl amino acid amino acid SH NH-methyl amino acid amino acid SH NH-ethyl amino acid amino acid SH NH-acetyl amino acid amino acid SH OH amino acid amino acid SH OMe amino acid amino acid SH OEt amino acid amino acid SH 0-cyclopropyl amino acid amino acid SH O-acetyl amino acid amino acid SH SH amino acid amino acid SH SMe amino acid amino acid SH SEt amino acid amino acid SH S-cyclopropyl R R X Y amino acid amino acid SH F amino acid amino acid SH Cl amino acid amino acid SH Br amino acid amino acid SH I amino acid H SH H amino acid H SH NH2 amino acid H SH NH-cyclopropyl amino acid H SH NH-methyl amino acid H SH NH-ethyl amino acid H SH NH-acetyl amino acid H SH OH amino acid H SH OMe amino acid H SH OEt amino acid H SH 0-cyclopropyl amino acid H SH O-acetyl amino acid H SH SH amino acid H SH SMe amino acid H SH SEt amino acid H SH S-cyclopropyl amino acid H SH F amino acid H SH Cl amino acid H SH Br amino acid H SH I amino acid acyl SH H amino acid acyl SH NH2 amino acid acyl SH NH-cyclopropyl amino acid acyl SH NH-methyl amino acid acyl SH NH-ethyl amino acid acyl SH NH-acetyl amino acid acyl SH OH amino acid acyl SH OMe amino acid acyl SH OEt amino acid acyl SH 0-cyclopropyl amino acid acyl SH O-acetyl amino acid acyl SH SH amino acid acyl SH SMe amino acid acyl SH SEt amino acid acyl SH S-cyclopropyl amino acid acyl SH F amino acid acyl SH Cl amino acid acyl SH Br amino acid acyl SH I acyl H C1 H acyl H C1 NH2 R R3 Xl acyl H Cl NH-cyclopropyl acyl H C1 NH-methyl acyl H C1 NH-ethyl acyl H C1 NH-acetyl acyl H C1 OH acyl H C1 OMe acyl H C1 OEt acyl 0-cyclopropyl acyl H Cl O-acetyl acy ! HC ! SH acyl H C1 SMe acyl H Cl SEt acyl H Cl S-cyclopropyl acyl H C1 F acyl H C1 Cl acyl H Cl Br acyl H C1 I acyl acyl C1 H acyl acyl C1 NH2 acyl acyl Cl NH-cyclopropyl acyl acyl Cl NH-methyl acyl acyl Cl NH-ethyl acyl acyl C1 NH-acetyl acyl acyl C1 OH acyl acyl C1 OMe acyl acyl C1 OEt acyl 0-cyclopropyl acyl acyl C1 O-acetyl acyl acyl C1 SH acyl acyl Cl SMe acyl acyl Cl SEt acyl acyl Cl S-cyclopropyl acyiacyiCl F acyl acyl Cl F acyl acyl ci ci acyl acyl Cl Br acyl acyl C1 I acyl amino acid C1 H acyl amino acid C1 NH2 acyl amino acid Cl NH-cyclopropyl acyl amino acid Cl NH-methyl acyl amino acid Cl NH-ethyl acyl amino acid C1 NH-acetyl acyl amino acid C1 OH acyl amino acid C1 OMe R2 R3 Xl acyl amino acid Cl OEt ac 1 amino acid Cl O-cyclo ro yl acyl amino acid Cl O-acetyl acyl amino acid C1 SH acyl amino acid ci SMe acyl amino acid Cl SEt acyl amino acid Cl S-cyclopropyl acyl amino acid Cl F acyl amino acid Cl Cl acyl amino acid Cl Br acyl amino acid Cl I H acyl C1 H H acyl Cl NH2 H acyl Cl NH-cyclopropyl H acyl Cl NH-methyl H acyl C1 NH-ethyl H acyl Cl NH-acetyl H acyl C1 OH H acyl C1 OMe H acyl C1 OEt H acyl Cl O-cyclopropyl H acyl C1 O-acetyl H acyl Cl SH H acyl Cl SMe H acyl C1 SEt H acyl C1 S-cyclopropyl H acyl C1 F H acyl Cl Cl H acyl C1 Br H acyl C1 H amino acid Cl H H amino acid C1 NH2 H amino acid Cl NH-cyclopropyl H amino acid Cl NH-methyl H amino acid Cl NH-ethyl H amino. acid Cl NH-acetyl H amino acid Cl OH amino acid C1 OMe H amino acid Cl OEt H amino acid Cl O-cyclopropyl H amino acid Cl O-acetyl H amino acid Cl SH H amino acid Cl SMe H amino acid Cl SEt R R X Y H amino acid Cl S-cyclopropyl amino acid C1 F amino acid C1 C1 amino acid C1 Br amino acid Cl I amino acid amino acid Cl H amino acid amino acid C1 NH2 amino acid amino acid Cl NH-cyclopropyl amino acid amino acid C1 NH-methyl amino acid amino acid C1 NH-ethyl amino acid amino acid C1 NH-acetyl amino acid amino acid Cl OH amino acid amino acid Cl OMe amino acid amino acid Cl OEt amino acid amino acid O-cyclopropyl amino acid amino acid Cl O-acetyl amino acid amino acid Cl SH amino acid amino acid Cl SMe amino acid amino acid Cl SEt amino acid amino acid Cl S-cyclopropyl amino acid amino acid Cl F amino acid amino acid Cl Cl amino acid amino acid Cl Br amino acid amino acid C1 I amino acid Cl H amino acid H Cl NH2 amino acid H Cl NH-cyclopropyl amino acid H Cl NH-methyl amino acid H Cl NH-ethyl amino acid H Cl NH-acetyl amino acid Cl OH amino acid C1 OMe amino acid H Cl OEt amino acid 0-cyclopropyl amino acid H Cl O-acetyl amino acid Cl SH amino acid Cl SMe amino acid H C1 SEt amino acid H Cl S-cyclopropyl amino acid H Cl F amino acid H Cl Cl amino acid H C1 Br amino acid H Cl I amino acid acyl Cl H R R3 Xl amino acid acyl Cl NH2 amino acid ac 1 Cl NH-cyclo ro yl amino acid acyl Cl NH-methyl amino acid acyl C1 NH-ethyl amino acid acyl Cl NH-acetyl amino acid acyl Cl OH amino acid acyl Cl OMe amino acid acyl Cl OEt amino acid acyl ci 0-cyclopropyl amino acid acyl Cl O-acetyl amino acid acyl Cl SH amino acid acyl Cl SMe amino acid acyl Cl SEt amino acid acyl Cl S-cyclopropyl amino acid acyl C1 F amino acid acyl Cl Cl amino acid acyl Cl Br amino acid acyl Cl I acyl H Br H acyl H Br NH2 acyl H Br NH-cyclopropyl acyl H Br NH-methyl acyl H Br NH-ethyl acyl H Br NH-acetyl acyl H Br OH acyl H Br OMe acyl H Br OEt acyl H Br O-cyclopropyl acyl H Br O-acetyl acyl H Br SH acyl H Br SMe acyl H Br SEt acyl H Br S-cyclopropyl acyl H Br F acyl H Br C1 acyl H Br Br acyl H Br I acyl acyl Br H acyl acyl Br NH2 acyl acyl Br NH-cyclopropyl acyl acyl Br NH-methyl acyl acyl Br NH-ethyl acyl acyl Br NH-acetyl acyl acyl Br OH R R X Y acyl acyl Br OMe acyl acyl Br OEt acyl acyl Br O-cyclopropyl acyl acyl Br O-acetyl acyl acyl Br SH acyl acyl Br SMe acyl acyl Br SEt acyl acyl Br S-cyclopropyl acyl acyl Br F acyl acyl Br C1 acyl acyl Br Br acyl acyl Br I acyl amino acid Br H acyl amino acid Br NH2 acyl amino acid Br NH-cyclopropyl acyl amino acid Br NH-methyl acyl amino acid Br NH-ethyl acyl amino acid Br NH-acetyl acyl amino acid Br OH acyl amino acid Br OMe acyl amino acid Br OEt acyl amino acid Br O-cyclopropyl acyl amino acid Br O-acetyl acyl amino acid Br SH acyl amino acid Br SMe acyl amino acid Br SEt acyl amino acid Br S-cyclopropyl acyl amino acid Br F acyl amino acid Br Cl acyl amino acid Br Br acyl amino acid Br I H acyl Br H H acyl Br NH2 H acyl Br NH-cyclopropyl H acyl Br NH-methyl H acyl Br NH-ethyl H acyl Br NH-acetyl H acyl Br OH H acyl Br OMe H acyl Br OEt H acyl Br O-cyclopropyl H acyl Br O-acetyl H acyl Br SH H acyl Br SMe R R X Y H acyl Br SEt H acyl Br S-cyclopropyl H acyl Br F acyl Br C1 H acyl Br Br H acyl Br I H amino acid Br H H amino acid Br NH2 H amino acid Br NH-cyclopropyl H amino acid Br NH-methyl H amino acid Br NH-ethyl H amino acid Br NH-acetyl H amino acid Br OH H amino acid Br OMe H amino acid Br OEt H amino acid Br 0-cyclopropyl H amino acid Br 0-acetyl H amino acid Br SH H amino acid Br SMe H amino acid Br SEt H amino acid Br S-cyclopropyl H amino acid Br F H amino acid Br Cl H amino acid Br Br H amino acid Br I amino acid amino acid Br H amino acid amino acid Br NH2 amino acid amino acid Br NH-cyclopropyl amino acid amino acid Br NH-methyl amino acid amino acid Br NH-ethyl amino acid amino acid Br NH-acetyl amino acid amino acid Br OH amino acid amino acid Br OMe amino acid amino acid Br OEt amino acid amino acid Br 0-cyclopropyl amino acid amino acid Br 0-acetyl amino acid amino acid Br SH amino acid amino acid Br SMe amino acid amino acid Br SEt amino acid amino acid Br S-cyclopropyl amino acid amino acid Br F amino acid amino acid Br Cl amino acid amino acid Br Br amino acid amino acid Br I R2 R3 Xl amino acid H Br H amino acid H Br NH2 amino acid H Br NH-cyclopropyl amino acid H Br NH-methyl amino acid H Br NH-ethyl amino acid H Br NH-acetyl amino acid H Br OH amino acid H Br OMe amino acid H Br OEt amino acid H Br 0-cyclopropyl amino acid H Br O-acetyl amino acid H Br SH amino acid H Br SMe amino acid H Br SEt amino acid H Br S-cyclopropyl amino acid H Br F amino acid H Br Cl amino acid H Br Br amino acid H Br I amino acid acyl Br H amino acid acyl Br NH2 amino acid acyl Br NH-cyclopropyl amino acid acyl Br NH-methyl amino acid acyl Br NH-ethyl amino acid acyl Br NH-acetyl amino acid acyl Br OH amino acid acyl Br OMe amino acid acyl Br OEt amino acid acyl Br O-cyclopropyl amino acid acyl Br O-acetyl amino acid acyl Br SH amino acid acyl Br SMe amino acid acyl Br SEt amino acid acyl Br S-cyclopropyl amino acid acyl Br F amino acid acyl Br Cl amino acid acyl Br Br amino acid acyl Br I acyl H NH2 H acyl H NH2 NH2 acyl H NH2 NH-cyclopropyl acyl H NH2 NH-methyl acyl H NH2 NH-ethyl acyl H NH2 NH-acetyl R2 R3 Xl acyl H NH2 OH acyl H NH2 OMe acyl H NH2 OEt acyl H NH2 0-cyclopropyl acyl H NH2 O-acetyl acyl H NH2 SH acyl H NH2 SMe acyl H NH2 SEt acyl H NH2 S-cyclopropyl acyl H NH2 F acyl H NH2 C1 acyl H NH2 Br acyl H NH2 I acyl acyl NH2 H acyl acyl NH2 NH2 acyl acyl NH2 NH-cyclopropyl acyl acyl NH2 NH-methyl acyl acyl NH2 NH-ethyl acyl acyl NH2 NH-acetyl acyl acyl NH2 OH acyl acyl NH2 OMe acyl acyl NH2 OEt acyl acyi NH2 O-cyclopropyl acyl acyl NH2 O-acetyl acyl acyl NH2 SH acyl acyl NH2 SMe acyl acyl NH2 SEt acyl acyl NH2 S-cyclopropyl acyl acyl NH2 F acyl acyl NH2 C1 acyl acyl NH2 Br acyl acyl NH2 I acyl amino acid NH2 H acyl amino acid NH2 NH2 acyl amino acid NH2 NH-cyclopropyl acyl amino acid NH2 NH-methyl acyl amino acid NH2 NH-ethyl acyl amino acid NH2 NH-acetyl acyl amino acid NH2 OH acyl amino acid NH2 OMe acyl amino acid NH2 OEt acyl amino acid NH2 O-cyclopropyl acyl amino acid NH2 O-acetyl acyl amino acid NH2 SH R R"X'Y acyl amino acid NH2 SMe acyl amino acid NH2 SEt acyl amino acid NH2 S-cyclopropyl acyl amino acid NH2 acyl amino acid NH2 Cl acyl amino acid NH2 Br acyl amino acid NH2 I H acyl NH2 H H acyl NH2 NH2 H acyl NH2 NH-cyclopropyl H acyl NH2 NH-methyl H acyl NH2 NH-ethyl H acyl NH2 NH-acetyl H acyl NH2 OH H acyl NH2 OMe H acyl NH2 OEt H acyl NH2 O-cyclopropyl H acyl NH2 O-acetyl H acyl NH2 SH H acyl NH2 SMe H acyl NH2 SEt H acyl NH2 S-cyclopropyl H acyl NH2 F H acyl NH2 Cl H acyl NH2 Br H acyl NH2 I H amino acid NH2 H H amino acid NH2 NH2 H amino acid NH2 NH-cyclopropyl H amino acid NH2 NH-methyl H amino acid NH2 NH-ethyl H amino acid NH2 NH-acetyl H amino acid NH2 OH H amino acid NH2 OMe H amino acid NH2 OEt H amino acid NH2 O-cyclopropyl H amino acid NH2 O-acetyl H amino acid NH2 SH H amino acid NH2 SMe H amino acid NH2 SEt H amino acid NH2 S-cyclopropyl H amino acid NH2 F H amino acid NH2 Cl H amino acid NH2 Br R2 R3 Xl H amino acid NH2 I amino acid amino acid NH2 H amino acid amino acid NH2 NH2 amino acid amino acid NH2 NH-cyclopropyl amino acid amino acid NH2 NH-methyl amino acid amino acid NH2 NH-ethyl amino acid amino acid NH2 NH-acetyl amino acid amino acid NH2 OH amino acid amino acid NH2 OMe amino acid amino acid NH2 OEt amino acid amino acid NH2 0-cyclopropyl amino acid amino acid NH2 O-acetyl amino acid amino acid NH2 SH amino acid amino acid NH2 SMe amino acid amino acid NH2 SEt amino acid amino acid NH2 S-cyclopropyl amino acid amino acid NH2 F amino acid amino acid NH2 Cl amino acid amino acid NH2 Br amino acid amino acid NH2 I amino acid H NH2 H amino acid H NH2 NH2 amino acid H NH2 NH-cyclopropyl amino acid H NH2 NH-methyl amino acid H NH2 NH-ethyl amino acid H NH2 NH-acetyl amino acid H NH2 OH amino acid H NH2 OMe amino acid H NH2 OEt amino acid H NH2 O-cyclopropyl amino acid H NH2 0-acetyl amino acid H NH2 SH amino acid H NH2 SMe amino acid H NH2 SEt amino acid H NH2 S-cyclopropyl amino acid H NH2 F amino acid H NH2 C1 amino acid H NH2 Br amino acid H NH2 I amino acid acyl NH2 H amino acid acyl NH2 NH2 amino acid acyl NH2 NH-cyclopropy amino acid acyl NH2 NH-methyl amino acid acyl NH2 NH-ethyl R R X Y amino acid acyl NH2 NH-acetyl amino acid acyl NH2 OH amino acid acyl NH2 OMe amino acid acyl NH2 OEt amino acid acyl NHZ O-cyclo ro yl amino acid acyl NH2 0-acetyl amino acid acyl NH2 SH amino acid acyl NH2 SMe amino acid acyl NH2 SEt amino acid acyl NH2 S-cyclopropyl amino acid acyl NH2 F amino acid acyl NH2 C1 amino acid acyl NH2 Br amino acid acyl NH2 I acyl H OH H acyl H OH NH2 acyl H OH NH-cyclopropyl acyl H OH NH-methyl acyl H OH NH-ethyl acyl H OH NH-acetyl acyl H OH OH acyl H OH OMe acyl H OH OEt acyl H OH O-cyclopropyl acyl H OH O-acetyl acyl H OH SH acyl H OH SMe acyl H OH SEt acyl H OH S-cyclopropyl acyl H OH F acyl H OH Cl acyl H OH Br acyl H OH I acyl acyl OH H acyl acyl OH NH2 acyl acyl OH NH-cyclopropyl acyl acyl OH NH-methyl acyl acyl OH NH-ethyl acyl acyl OH NH-acetyl acyl acyl OH OH acyl acyl OH OMe acyl acyl OH OEt acyl acyl OH 0-cyclopropyl acyl acyl OH O-acetyl R R3 Xl acyl acyl OH SH acyl acyl OH SMe acyl acyl OH SEt acyl acyl OH S-cyclopropyl acyl acyl OH F acyl acyl OH Cl acyl acyl OH Br acyl acyl OH I acyl amino acid OH H acyl amino acid OH NH2 acyl amino acid OH NH-cyclopropyl acyl amino acid OH NH-methyl acyl amino acid OH NH-ethyl acyl amino acid OH NH-acetyl acyl amino acid OH OH acyl amino acid OH OMe acyl amino acid OH OEt acyl amino acid OH 0-cyclopropyl acyl amino acid OH O-acetyl acyl amino acid OH SH acyl amino acid OH SMe acyl amino acid OH SEt acyl amino acid OH S-cyclopropyl acyl amino acid OH F acyl amino acid OH C1 acyl amino acid OH Br acyl amino acid OH I H acyl OH H H acyl OH NH2 H acyl OH NH-cyclopropyl H acyl OH NH-methyl H acyl OH NH-ethyl H acyl OH NH-acetyl H acyl OH OH H acyl OH OMe H acyl OH OEt H acyl OH 0-cyclopropyl H acyl OH O-acetyl H acyl OH SH H acyl OH SMe H acyl OH SEt H acyl OH S-cyclopropyl H acyl OH F H acyl OH C1 R R X Y H acyl OH Br H acyl OH I H amino acid OH H H amino acid OH NH2 H amino acid OH NH-cyclopropyl H amino acid OH NH-methyl H amino acid OH NH-ethyl H amino acid OH NH-acetyl H amino acid OH OH H amino acid OH OMe H amino acid OH OEt H amino acid OH 0-cyclopropyl H amino acid OH O-acetyl H amino acid OH SH H amino acid OH SMe H amino acid OH SEt H amino acid OH S-cyclopropyl amino acid OH F H amino acid OH Cl H amino acid OH Br H amino acid OH I amino acid amino acid OH H amino acid amino acid OH NH2 amino acid amino acid OH NH-cyclopropyl amino acid amino acid OH NH-methyl amino acid amino acid OH NH-ethyl amino acid amino acid OH NH-acetyl amino acid amino acid OH OH amino acid amino acid OH OMe amino acid amino acid OH OEt amino acid amino acid OH 0-cyclopropyl amino acid amino acid OH O-acetyl amino acid amino acid OH SH amino acid amino acid OH SMe amino acid amino acid OH SEt amino acid amino acid OH S-cyclopropyl amino acid amino acid OH F amino acid amino acid OH Cl amino acid amino acid OH Br amino acid amino acid OH I amino acid H OH H amino acid H OH NH2 amino acid H OH NH-cyclopropyl amino acid H OH NH-methyl R R X Y amino acid H OH NH-ethyl amino acid H OH NH-acetyl amino acid H OH OH amino acid H OH OMe amino acid H OH OEt amino acid H OH 0-cyclopropyl amino acid H OH O-acetyl amino acid H OH SH amino acid H OH SMe amino acid OH SEt amino acid H OH S-cyclopropyl amino acid OH F amino acid H OH Cl amino acid H OH Br amino acid H OH I amino acid acyl OH H amino acid acyl OH NH2 amino acid acyl OH NH-cyclopropyl amino acid acyl OH NH-methyl amino acid acyl OH NH-ethyl amino acid acyl OH NH-acetyl amino acid acyl OH OH amino acid acyl OH OMe amino acid acyl OH OEt amino acid acyl OH 0-cyclopropyl amino acid acyl OH O-acetyl amino acid acyl OH SH amino acid acyl OH SMe amino acid acyl OH SEt amino acid acyl OH S-cyclopropyl amino acid acyl OH F amino acid acyl OH Cl amino acid acyl OH Br amino acid acyl OH I acyl H F H acyl H F NH2 acyl H F NH-cyclopropyl acyl H F NH-methyl acyl H F NH-ethyl acyl H F NH-acetyl acyl H F OH acyl H F OMe acyl H F OEt acyl H F O-cyclopropyl R2 R il acyl H F O-acetyl acyl H F SH acyl H F SMe acyl H F SEt acyl F S-cyclopropyl acyl H F F acyl H F C1 acyl H F Br acyl H F I acyl acyl F H acyl acyl F NH2 acyl acyl F NH-cyclopropyl acyl acyl F NH-methyl acyl acyl F NH-ethyl acyl acyl F NH-acetyl acyl acyl F OH acyl acyl F OMe acyl acyl F OEt acyl acyl F 0-cyclopropyl acyl acyl F O-acetyl acyl acyl F SH acyl acyl F SMe acyl acyl F SEt acyl acyl F S-cyclopropyl acyl acyl F F acyl acyl F Cl acyl acyl F Br acyl acyl F acyl amino acid F H acyl amino acid F NH2 acyl amino acid F NH-cyclopropyl acyl amino acid F NH-methyl acyl amino acid F NH-ethyl acyl amino acid F NH-acetyl acyl amino acid F OH acyl amino acid F OMe acyl amino acid F OEt acyl amino acid F O-cyclopropyl acyl amino acid F O-acetyl acyl amino acid F SH acyl amino acid F SMe acyl amino acid F SEt acyl amino acid F S-cyclopropyl acyl amino acid F F R R""X'Y acyl amino acid F C1 acyl amino acid F Br acyl amino acid F I H acyl F H H acyl F NH2 H acyl F NH-cyclopropyl H acyl F NH-methyl H acyl F NH-ethyl H acyl F NH-acetyl H acyl F OH H acyl F OMe H acyl F OEt H acyl F 0-cyclopropyl H acyl F O-acetyl H acyl F SH H acyl F SMe H acyl F SEt H acyl F S-cyclopropyl H acyl F F H acyl F Cl H acyl F Br H acyl F I H amino acid F H H amino acid F NH2 H amino acid F NH-cyclopropyl H amino acid F NH-methyl H amino acid F NH-ethyl H amino acid F NH-acetyl H amino acid F OH H amino acid F OMe H amino acid F OEt H amino acid F 0-cyclopropyl H amino acid F 0-acetyl H amino acid F SH H amino acid F SMe H amino acid F SEt H amino acid F S-cyclopropyl H amino acid F F H amino acid F C1 H amino acid F Br H amino acid F I amino acid amino acid F H amino acid amino acid F NH2 amino acid amino acid F NH-cyclopropyl R R X Y amino acid amino acid F NH-methyl amino acid amino acid F NH-ethyl amino acid amino acid F NH-acetyl amino acid amino acid F OH amino acid amino acid F OMe amino acid amino acid F OEt amino acid amino acid F O-cyclopropyl amino acid amino acid F O-acetyl amino acid amino acid F SH amino acid amino acid F SMe amino acid amino acid F SEt amino acid amino acid F S-cyclopropyl amino acid amino acid F F amino acid amino acid F Cl amino acid amino acid F Br amino acid amino acid F I amino acid H F H amino acid H F NH2 amino acid H F NH-cyclopropyl amino acid H F NH-methyl amino acid H F NH-ethyl amino acid H F NH-acetyl amino acid H F OH amino acid H F OMe amino acid H F OEt amino acid H F O-cyclo ro yl amino acid H F O-acetyl amino acid H F SH amino acid H F SMe amino acid H F SEt amino acid H F S-cyclopropyl amino acid H F F amino acid H F Cl amino acid H F Br amino acid H F I amino acid acyl F H amino acid acyl F NH2 amino acid acyl F NH-cyclopropyl amino acid acyl F NH-methyl amino acid acyl F NH-ethyl amino acid acyl F NH-acetyl amino acid acyl F OH amino acid acyl F OMe amino acid acyl F OEt R R3 Xl amino acid acyl F O-cyclopropyl amino acid acyl F O-acetyl amino acid acyl F SH amino acid acyl F SMe amino acid acyl F SEt amino acid acyl F S-cyclopropyl amino acid acyl F F amino acid acyl F C1 amino acid acyl F Br amino acid acyl F I acyl H I H acyl H I NH2 acyl H I NH-cyclopropyl acyl H NH-methyl acyl H NH-ethyl acyl H I NH-acetyl acyl H I OH acyl H I OMe acyl H I OEt acyl H I O-cyclopropyl acyl H I O-acetyl acyl H I SH acyl H I SMe acyl H I SEt acyl H S-cyclopropyl acyl H I F acyl H I C1 acyl H I Br acyl H I I acyl acyl I H acyl acyl I NH2 acyl acyl I NH-cyclopropyl acyl acyl I NH-methyl acyl acyl I NH-ethyl acyl acyl I NH-acetyl acyl acyl I OH acyl acyl I OMe acyl acyl I OEt acyl acyl I O-cyclo ro yl acyl acyl I 0-acetyl acyl acyl I SH acyl acyl I SMe acyl acyl I SEt acyl acyl I S-cyclopropyl R R3 X1 acyl acyl I F acyl acyl I C1 acyl acyl I Br acyl acyl I I acyl amino acid I H acyl amino acid I NH2 acyl amino acid I NH-cyclopropyl acyl amino acid I NH-methyl acyl amino acid I NH-ethyl acyl amino acid I NH-acetyl acyl amino acid I OH acyl amino acid I OMe acyl amino acid I OEt acyl amino acid I O-cyclopropyl acyl amino acid I O-acetyl acyl amino acid I SH acyl amino acid I SMe acyl amino acid I SEt acyl amino acid I S-cyclopropyl acyl amino acid I F acyl amino acid I Cl acyl amino acid I Br acyl amino acid I I H acyl I H H acyl I NH2 H acyl I NH-cyclopropyl H acyl I NH-methyl H acyl I NH-ethyl H acyl I NH-acetyl H acyl I OH H acyl I OMe H acyl I OEt H acyl I O-cyclopro yl H acyl I 0-acetyl H acyl I SH H acyl I SMe H acyl I SEt H acyl I S-cyclopropyl H acyl I F H ac 1 I C1 H acyl I Br H acyl I I H amino acid I H H amino acid I NH2 R R X Y H amino acid I NH-cyclopropyl H amino acid I NH-methyl H amino acid I NH-ethyl H amino acid I NH-acetyl H amino acid I OH H amino acid I OMe H amino acid I OEt H amino acid I 0-cyclopropyl H amino acid I O-acetyl H amino acid I SH H amino acid I SMe H amino acid I SEt H amino acid I S-cycloprogyl H amino acid I F H amino acid I Cl H amino acid I Br H amino acid I I amino acid amino acid I H amino acid amino acid I NH2 amino acid amino acid I NH-cyclopropyl amino acid amino acid I NH-methyl amino acid amino acid I NH-ethyl amino acid amino acid I NH-acetyl amino acid amino acid I OH amino acid amino acid I OMe amino acid amino acid I OEt amino acid amino acid I 0-cyclopropyl amino acid amino acid I O-acetyl amino acid amino acid I SH amino acid amino acid I SMe amino acid amino acid SEt amino acid amino acid I S-cyclopropyl amino acid amino acid I F amino acid amino acid C1 amino acid amino acid I Br amino acid amino acid I I amino acid H I H amino acid H I NH2 amino acid H I NH-cyclopropyl amino acid H I NH-methyl amino acid H I NH-ethyl amino acid H I NH-acetyl amino acid H I OH amino acid H I OMe R2 R il amino acid H I OEt amino acid H I O-c clo ro yl amino acid H I O-acetyl amino acid H I SH amino acid H I SMe amino acid H I SEt amino acid H I S-cyclopropyl amino acid H I F amino acid H I Cl amino acid H I Br amino acid H I I amino acid acyl I H amino acid acyl I NH2 amino acid acyl I NH-cyclopropyl amino acid acyl I NH-methyl amino acid acyl I NH-ethyl amino acid acyl I NH-acetyl amino acid acyl OH amino acid acyl I OMe amino acid acyl I OEt amino acid acyl I O-c clopropyl amino acid acyl I O-acetyl amino acid acyl I SH amino acid acyl I SMe amino acid acyl I SEt amino acid acyl I S-cyclopropyl amino acid acyl I F amino acid acyl I Cl amino acid acyl I Br amino acid acyl I I Table 3 R2 R3 R 6 X Base acyl H CH3 0 Thymine acyl H CH3 O Uracil acyl H CH3 O Guanine acyl H CH3 O Cytosine acyl H CH3 O Adenine acyl H CH3 O Hypoxanthine acyl H CH3 O 5-Fluorouracil acyl H CH3 O 8-Fluoroguanine acyl H CH3 O 5-Fluorocytosine acyl H CH3 O 8-Fluoroadenine acyl H CH3 O 2-Fluoroadenine acyl H CH3 O 2, 8-Difluoroadenine acyl H CH3 O 2-Fluorohypoxanthine acyl H CH3 O 8-Fluorohypoxanthine acyl H CH3 O 2, 8-Difluorohypoxanthine acyl H CH3 O 2-Aminoadenine acyl H CH3 O 2-Amino-8-fluoroadenine acyl H CH3 O 2-Amino-8-fluorohypoxanthine acyl HCH30 2-Aminohypoxanthine acyl H CH3 O 2-N-acetylguanine acyl H CH3 O 4-N-acetylcytosine acyl H CH3 O 6-N-acetyladenine acyl H CH3 O 2-N-acetyl-8-fluoroguanine acyl H CH3 O 4-N-acetyl-5-fluorocytosine acyl H CH3 O 6-N-acetyl-2-fluoroadenine ac 1 H CH3 O 6-N-acet 1-2, 8-difluoroadenine acyl H CH3 O 6-N-acetyl-2-aminoadenine acyl H CH3 0 6-N-acetyl-2-amino-8-fluoroadenine acyl CH3 O 2-N-acetylaminoadenine acyl CH3 O 2-N-acetylamino-8-fluoroadenine acyl H CH3 O 2-N-acetylamino-8-fluorohypoxanthine acyl H CH3 O 2-N-acetylaminohypoxanthine acyl acyl CH3 O Thymine acyl acyl CH3 O Uracil acyl acyl CH3 O Guanine acyl acyl CH3 O Cytosine acyl acyl CH3 O Adenine acyl acyl CH3 0 Hypoxanthine acyl acyl CH3 O 5-Fluorouracil acyl acyl CH3 O 8-Fluoroguanine acyl acyl CH3 O 5-Fluorocytosine acyl acyl CH3 O 8-Fluoroadenine acyl acyl CH3 O 2-Fluoroadenine acul acyl CH3 O 2, 8-Difluoroadenine acyl acyl CH3 O 2-Fluorohypoxanthine R R R X Base acyl acyl CH3 O 8-Fluorohypoxanthine acyl acyl CH3 O 2, 8-Difluorohypoxanthine acyl acyl CH3 O 2-Aminoadenine acyl acyl CH3 O 2-Amino-8-fluoroadenine acyl acyl CH3 O 2-Amino-8-fluorohypoxanthine acyl acyl CH3 O 2-Aminohypoxanthine acyl acyl CH3 O 2-N-acetylguanine acyl acyl CH3 O 4-N-acetylcytosine acyl acyl CH3 O 6-N-acetyladenine acyl acyl CH3 O 2-N-acetyl-8-fluoroguanine acyl acyl CH3 O 4-N-acetyl-5-fluorocytosine acyl acyl CH3 O 6-N-acetyl-2-fluoroadenine acyl acyl CH3 O 6-N-acetyl-2, 8-difluoroadenine acyl acyl CH3 O 6-N-acetyl-2-aminoadenine acyl acyl CH3 O 6-N-acetyl-2-amino-8-fluoroadenine acyl acyl CH3 O 2-N-acetylaminoadenine aceI aceI CH3 O 2-N-acetylamino-8-fluoroadenine ac 1 acyl CH3 O 2-N-acet lamino-8-fluorohy oxanthine acyl acyl CH3 O 2-N-acetylaminohypoxanthine acyl amino acid CH3 O Thymine acyl amino acid CH3 O Uracil acyl amino acid CH3 O Guanine acyl amino acid CH3 O Cytosine acyl amino acid CH3 O Adenine acyl amino acid CH3 O Hypoxanthine acyl amino acid CH3 O 5-Fluorouracil acyl amino acid CH3 O 8-Fluoroguanine acyl amino acid CH3 O 5-Fluorocytosine acyl amino acid CH3 O 8-Fluoroadenine acyl amino acid CH3 O 2-Fluoroadenine acyl amino acid CH3 0 2, 8-Difluoroadenine acYI amino acid CH3 O 2-Fluorohypoxanthine acyl amino acid CH3 O 8-Fluorohypoxanthine acyl amino acid CH3 O 2, 8-Difluorohypoxanthine acyl amino acid CH3 O 2-Aminoadenine acyl amino acid CH3 O 2-Amino-8-fluoroadenine acyl amino acid CH3 O 2-Amino-8-fluorohypoxanthine acyl amino acid CH3 O 2-Aminohypoxanthine acyl amino acid CH3 O 2-N-acetylguanine acyl amino acid CH3 O 4-N-acetylcytosine acyl amino acid CH3 O 6-N-acetyladenine acyl amino acid CH3 O 2-N-acetyl-8-fluoroguanine acyl amino acid CH3 O 4-N-acetyl-5-fluorocytosine f acyl amino acid CH3 O 6-N-acetyl-2-fluoroadenine acyl amino acid CH3 O 6-N-acetyl-2, 8-difluoroadenine acyl amino acid CH3 O 6-N-acetyl-2-aminoadenine acyl amino acid CH3 O 6-N-acetyl-2-amino-8-fluoroadenine R R R"X Base acyl amino acid CH3 0 2-N-acetylaminoadenine acyl amino acid CH3 O 2-N-acetylamino-8-fluoroadenine acyl amino acid CH3 O 2-N-acetylamino-8-fluorohypoxanthine acyl amino acid CH3 O 2-N-acetylaminohypoxanthine H acyl CH3 O Thymine H acyl CH3 O Uracil H acyl CH3 O Guanine H acyl CH3 O Cytosine H acyl CH3 O Adenine H acyl CH3 O Hypoxanthine H acyl CH3 O 5-Fluorouracil H acyl CH3 O 8-Fluoroguanine H acyl CH3 O 5-Fluorocytosine H acyl CH3 O 8-Fluoroadenine H acyl CH3 O 2-Fluoroadenine H acyl CH3 O 2, 8-Difluoroadenine H acyl CH3 O 2-Fluorohypoxanthine H acyl CH3 O 8-Fluorohypoxanthine H acyl CH3 O 2, 8-Difluorohypoxanthine H acyl CH3 O 2-Aminoadenine H acyl CH3 O 2-Amino-8-fluoroadenine H acyl CH3 O 2-Amino-8-fluorohypoxanthine H acyl CH3 O 2-Aminohypoxanthine H acyl CH3 O 2-N-acetylguanine H acyl CH3 O 4-N-acetylcytosine H acyl CH3 O 6-N-acetyladenine H acyl CH3 O 2-N-acetyl-8-fluoroguanine H acyl CH3 O 4-N-acetyl-5-fluorocytosine H acyl CH3 O 6-N-acetyl-2-fluoroadenine H acyl CH3 O 6-N-acetyl-2, 8-difluoroadenine H acyl CH3 O 6-N-acetyl-2-aminoadenine H acyl CH3 O 6-N-acetyl-2-amino-8-fluoroadenine H acyl CH3 O 2-N-acetylaminoadenine H acyl CH3 O 2-N-acetylamino-8-fluoroadenine H acyl CH3 O 2-N-acetylamino-8-fluorohypoxanthine H acyl CH3 O 2-N-acetylaminohypoxanthine H amino acid CH3 O Thymine H amino acid CH3 O Uracil H amino acid CH3 O Guanine H amino acid CH3 O Cytosine H amino acid CH3 O Adenine H amino acid CH3 O Hypoxanthine H amino acid CH3 O 5-Fluorouracil H amino acid CH3 O 8-Fluoroguanine H amino acid CH3 O 5-Fluorocytosine H amino acid CH3 O 8-Fluoroadenine H amino acid CH3 O 2-Fluoroadenine R2 R3 R X Base H amino acid CH3 O 2, 8-Difluoroadenine H amino acid CH3 O 2-Fluorohypoxanthine H amino acid CH3 O 8-Fluorohypoxanthine H amino acid CH3 O 2, 8-Difluorohypoxanthine H amino acid CH3 O 2-Aminoadenine H amino acid CH3 O 2-Amino-8-fluoroadenine H amino acid CH3 O 2-Amino-8-fluorohypoxanthine H amino acid CH3 O 2-Aminohypoxanthine H amino acid CH3 O 2-N-acetylguanine H amino acid CH3 O 4-N-acetylcytosine H amino acid CH3 O 6-N-acetyladenine H amino acid CH3 O 2-N-acetyl-8-fluoroguanine H amino acid CH3 O 4-N-acetyl-5-fluorocytosine H amino acid CH3 O 6-N-acetyl-2-fluoroadenine H amino acid CH3 O 6-N-acetyl-2, 8-difluoroadenine H amino acid CH3 O 6-N-acetyl-2-aminoadenine H amino acid CH3 O 6-N-acetyl-2-amino-8-fluoroadenine H amino acid CH3 O 2-N-acetylaminoadenine H amino acid CH3 O 2-N-acetylamino-8-fluoroadenine H amino acid CH3 O 2-N-acetylamino-8-fluorohypoxanthine H amino acid CH3 O 2-N-acetylaminohypoxanthine amino acid amino acid CH3 O Thymine amino acid amino acid CH3 O Uracil amino acid amino acid CH3 O Guanine amino acid amino acid CH3 O Cytosine amino acid amino acid CH3 O Adenine amino acid amino acid CH3 O Hypoxanthine amino acid amino acid CH3 O 5-Fluorouracil amino acid amino acid CH3 O 8-Fluoroguanine amino acid amino acid CH3 O 5-Fluorocytosine amino acid amino acid CH3 O 8-Fluoroadenine amino acid amino acid CH3 O 2-Fluoroadenine amino acid amino acid CH3 O 2, 8-Difluoroadenine amino acid amino acid CH3 O 2-Fluorohypoxanthine amino acid amino acid CH3 O 8-Fluorohypoxanthine amino acid amino acid CH3 O 2, 8-Difluorohypoxanthine amino acid amino acid CH3 O 2-Aminoadenine amino acid amino acid CH3 O 2-Amino-8-fluoroadenine amino acid amino acid CH3 O 2-Amino-8-fluorohypoxanthine amino acid amino acid CH3 O 2-Aminohypoxanthine amino acid amino acid CH3 O 2-N-acetylguanine amino acid amino acid CH3 O 4-N-acetylcytosine amino acid amino acid CH3 O 6-N-acetyladenine amino acid amino acid CH3 O 2-N-acetyl-8-fluoroguanine amino acid amino acid CH3 O 4-N-acetyl-5-fluorocytosine amino acid amino acid CH3 O 6-N-acetyl-2-fluoroadenine amino acid amino acid CH3 O 6-N-acetyl-2, 8-difluoroadenine R R R X Base amino acid amino acid CH3 O 6-N-acetyl-2-aminoadenine amino acid amino acid CH3 O 6-N-acetyl-2-amino-8-fluoroadenine amino acid amino acid CH3 O 2-N-acetylaminoadenine amino acid amino acid CH3 O 2-N-acetylamino-8-fluoroadenine amino acid amino acid CH3 O 2-N-acetylamino-8-fluorohypoxanthine amino acid amino acid CH3 O 2-N-acetylaminohypoxanthine amino acid H CH3 O Thymine amino acid H CH3 O Uracil amino acid H CH3 O Guanine amino acid H CH3 O Cytosine amino acid H CH3 O Adenine amino acid H CH3 O Hypoxanthine amino acid H CH3 O 5-Fluorouracil amino acid H CH3 O 8-Fluoroguanine amino acid H CH3 O 5-Fluorocytosine amino acid H CH3 O 8-Fluoroadenine amino acid H CH3 O 2-Fluoroadenine amino acid H CH3 O 2, 8-Difluoroadenine amino acid H CH3 O 2-Fluorohypoxanthine amino acid H CH3 O 8-Fluorohypoxanthine amino acid H CH3 O 2, 8-Difluorohypoxanthine amino acid H CH3 O 2-Aminoadenine amino acid H CH3 O 2-Amino-8-fluoroadenine amino acid H CH3 O 2-Amino-8-fluorohypoxanthine amino acid H CH3 O 2-Aminohypoxanthine amino acid H CH3 O 2-N-acetylguanine amino acid H CH3 O 4-N-acetylcytosine amino acid H CH3 O 6-N-acetyladenine amino acid H CH3 O 2-N-acetyl-8-fluoroguanine amino acid H CH3 O 4-N-acetyl-5-fluorocytosine amino acid H CH3 O 6-N-acetyl-2-fluoroadenine amino acid H CH3 O 6-N-acetyl-2, 8-difluoroadenine amino acid H CH3 O 6-N-acetyl-2-aminoadenine amino acid H CH3 O 6-N-acetyl-2-amino-8-fluoroadenine amino acid H CH3 O 2-N-acetylaminoadenine amino acid H CH3 O 2-N-acetylamino-8-fluoroadenine amino acid H CH3 O 2-N-acetylamino-8-fluorohypoxanthine amino acid H CH3 O 2-N-acetylaminohypoxanthine amino acid acyl CH3 O Thymine amino acid acyl CH3 O Uracil amino acid acyl CH3 O Guanine amino acid acyl CH3 O Cytosine amino acid acyl CH3 O Adenine amino acid acyl CH3 O Hypoxanthine amino acid acyl CH3 O 5-Fluorouracil amino acid acyl CH3 O 8-Fluoroguanine amino acid acyl CH3 O 5-Fluorocytosine R R R X Base amino acid acyl CH3 O 8-Fluoroadenine amino acid acyl CH3 O 2-Fluoroadenine amino acid acyl CH3 O 2, 8-Difluoroadenine amino acid acyl CH3 O 2-Fluorohypoxanthine amino acid acyl CH3 O 8-Fluorohypoxanthine amino acid acyl CH3 O 2, 8-Difluorohypoxanthine amino acid acyl CH3 O 2-Aminoadenine amino acid acyl CH3 O 2-Amino-8-fluoroadenine amino acid acyl CH3 O 2-Amino-8-fluorohypoxanthine amino acid acyl CH3 O 2-Aminohypoxanthine amino acid acyl CH3 O 2-N-acetylguanine amino acid acyl CH3 O 4-N-acetylcytosine amino acid acyl CH3 O 6-N-acetyladenine amino acid acyl CH3 O 2-N-acetyl-8-fluoroguanine amino acid acyl CH3 O 4-N-acetyl-5-fluorocytosine amino acid acyl CH3 O 6-N-acetyl-2-fluoroadenine amino acid acyl CH3 O 6-N-acetyl-2, 8-difluoroadenine amino acid acyl CH3 O 6-N-acetyl-2-aminoadenine amino acid acyl CH3 O 6-N-acetyl-2-amino-8-fluoroadenine amino acid acyl CH3 O 2-N-acetylaminoadenine amino acid acyl CH3 O 2-N-acetylamino-8-fluoroadenine amino acid acyl CH3 O 2-N-acetylamino-8-fluorohypoxanthine amino acid acyl CH3 O 2-N-acet laminoh oxanthine acyl H CH3 S Thymine acyl H CH3 S Uracil acyl H CH3 S Guanine acyl H CH3 S Cytosine acyl H CH3 S Adenine acyl H CH3 S Hypoxanthine acyl H CH3 S 5-Fluorouracil acyl H CH3 S uoroguanine acyl H CH3 S 5-Fluorocytosine acyl H CH3 S 8-Fluoroadenine acyl H CH3 S 2-Fluoroadenine acyl H CH3 S 2, 8-Difluoroadenine acyl H CH3 S 2-Fluorohypoxanthine acyl H CH3 S 8-Fluorohypoxanthine acyl H CH3 S 2, 8-Difluorohypoxanthine acyl H CH3 S 2-Aminoadenine acyl H CH3 S 2-Amino-8-fluoroadenine acyl H CH3 S 2-Amino-8-fluorohypoxanthineX acyl H CH3 S 2-Aminohy oxanthine acyl H CH3 S 2-N-acetyXuanine acyl H CH3 S 4-N-acetylcytosine acyl H CH3 S 6-N-acetyladenine acyl H CH3 S 2-N-acetyl-8-fluoroguanine acyl H CH3 S 4-N-acetyl-5-fluorocytosine R R R X Base acyl H CH3 S 6-N-acetyl-2-fluoroadenine acyl H CH3 S 6-N-acetyl-2, 8-difluoroadenine acyl H CH3 S 6-N-acetyl-2-aminoadenine acyl H CH3 S 6-N-acetYI-2-amino-8-fluoroadenine acyl H CH3 S 2-N-acetylaminoadenine acyl H CH3 S 2-N-acetylamino-8-fluoroadenine acyl H CH3 S 2-N-acetylamino-8-fluorohypoxanthine acyl H CH3 S 2-N-acetylaminohypoxanthine acyl acyl CH3 S Thymine acyl acyl CH3 S Uracil acyl acyl CH3 S Guanine acyl acyl CH3 S Cytosine acy1 acyl CH3 S Adenine acyl acyl CH3 S Hypoxanthine acyl acyl CH3 S 5-Fluorouracil acyl acyl CH3 S 8-Fluoroguanine acyl acyl CH3 S 5-Fluorocytosine acyl acyl CH3 S 8-Fluoroadenine acyl acyl CH3 S 2-Fluoroadenine acyl acyl CH3 S 2, 8-Difluoroadenine acyl acyl CH3 S 2-Fluorohypoxanthine acyl acyl CH3 S 8-Fluorohypoxanthine acyl acyl CH3 S 2, 8-Difluorohypoxanthine acyl acyl CH3 S 2-Aminoadenine acyl acyl CH3 S 2-Amino-8-fluoroadenine acyl acyl CH3 S 2-Amino-8-fluorohypoxanthine acyl acyl CH3 S 2-Aminohypoxanthine acyl acyl CH3 S 2-N-acetylguanine acyl acyl CH3 S 4-N-acetylcytosine acyl acyl CH3 S 6-N-acetyladenine acyl acyl CH3 S 2-N-acetyl-8-fluoroguanine acyl acyl CH3 S 4-N-acetyl-5-fluorocytosine acyl acyl CH3 S 6-N-acetyl-2-fluoroadenine acyl acyl CH3 S 6-N-acetyl-2, 8-difluoroadenine acyl acyl CH3 S 6-N-acetyl-2-aminoadenine acyl acyl CH3 S 6-N-acetyl-2-amino-8-fluoroadenine acyl acyl CH3 S 2-N-acetylaminoadenine acyl acyl CH3 S 2-N-acetylamino-8-fluoroadenine acyl acyl CH3 S 2-N-acetylamino-8-fluorohypoxanthine acyl acyl CH3 S 2-N-acetylaminohypoxanthine acyl amino acid CH3 S Thymine acyl amino acid CH3 S Uracil acyl amino acid CH3 S Guanine acyl amino acid CH3 S Cytosine acyl amino acid CH3 S Adenine acyl amino acid CH3 S Hypoxanthine acyl amino acid CH3 S 5-Fluorouracil R R6 X Base acyl amino acid CH3 S 8-Fluoroguanine acyl amino acid CH3 S 5-Fluorocytosine acyl amino acid CH3 S 8-Fluoroadenine acyl amino acid CH3 S 2-Fluoroadenine acyl amino acid CH3 S 2, 8-Difluoroadenine acyl amino acid CH3 S 2-Fluorohypoxanthine acyl amino acid CH3 S 8-Fluorohypoxanthine acyl amino acid CH3 S 2, 8-Difluorohypoxanthine acyl amino acid CH3 S 2-Aminoadenine acyl amino acid CH3 S 2-Amino-8-fluoroadenine acyl amino acid CH3 S 2-Amino-8-fluorohypoxanthine acyl amino acid CH3 S 2-Aminohypoxanthine acyl amino acid CH3 S 2-N-acetylguanine acyl amino acid CH3 S 4-N-acetylcytosine acyl amino acid CH3 S 6-N-acetyladen ine acyl amino acid CH3 S 2-N-acetyl-8-fluoroguanine acyl amino acid CH3 S 4-N-acetyl-5-fluorocytosine acyl amino acid CH3 S 6-N-acetyl-2-fluoroadenine acyl amino acid CH3 S 6-N-acetyl-2, 8-difluoroadenine acyl amino acid CH3 S 6-N-acetYI-2-am inoadenine acyl amino acid CH3 S 6-N-acetyl-2-amino-8-fluoroadenine acyl amino acid CH3 S 2-N-acetylaminoadenine acyl amino acid CH3 S 2-N-acetylamino-8-fluoroadenine acyl amino acid CH3 S 2-N-acetylamino-8-fluorohypoxanthine acyl amino acid CH3 S 2-N-acetylaminohypoxanthine H acyl CH3 S Thymine H acyl CH3 S Uracil H acyl CH3 S Guanine H acyl CH3 S Cytosine H acyl CH3 S Adenine H acyl CH3 S Hypoxanthine H acyl CH3 S 5-Fluorouracil H acyl CH3 S 8-Fluoroguanine H acyl CH3 S 5-Fluorocytosine H acyl CH3 S 8-Fluoroadenine H acyl CH3 S 2-Fluoroadenine H acyl CH3 S 2, 8-Difluoroadenine H acyl CH3 S 2-Fluorohypoxanthine H acyl CH3 S 8-Fluorohypoxanthine H acYI CH3 S 2, 8-Difluorohvnoxanthine H acyl CH3 S 2-Aminoadenine H acyl CH3 S 2-Amino-8-fluoroadenine H acyl CH3 S 2-Amino-8-fluorohypoxanthine H acyl CH3 S 2-Aminohypoxanthine H acyl CH3 S 2-N-acetylguanine H acyl CH3 S 4-N-acetylcytosine H acyl CH3 S 6-N-acetyladenine R2 R3 R6 X Base H acyl CH3 S 2-N-acetyl-8-fluoroguanine H acyl CH3 S 4-N-acetyl-5-fluorocytosine H acyl CH3 S 6-N-acetyl-2-fluoroadenine H acyl CH3 S 6-N-acetyl-2, 8-difluoroadenine H acyl CH3 S 6-N-acetyl-2-aminoadenine H acyl CH3 S 6-N-acetyl-2-amino-8-fluoroadenine H acyl CH3 S 2-N-acetylaminoadenine H acyl CH3 S 2-N-acetylamino-8-fluoroadenine H acyl CH3 S 2-N-acetylamino-8-fluorohypoxanthine H acyl CH3 S 2-N-acetylaminohypoxanthine H amino acid CH3 S Thymine H amino acid CH3 S Uracil H amino acid CH3 S Guanine H amino acid CH3 S Cytosine H amino acid CH3 S Adenine H amino acid CH3 S Hypoxanthine H amino acid CH3 S 5-Fluorouracil H amino acid CH3 S 8-Fluoroguanine H amino acid CH3 S 5-Fluorocytosine H amino acid CH3 S 8-Fluoroadenine H amino acid CH3 S 2-Fluoroadenine H amino acid CH3 S 2, 8-Difluoroadenine H amino acid CH3 S 2-Fluorohypoxanthine H amino acid CH3 S 8-Fluorohypoxanthine H amino acid CH3 S 2, 8-Difluorohypoxanthine H amino acid CH3 S 2-Aminoadenine H amino acid CH3 S 2-Amino-8-fluoroadenine H amino acid CH3 S 2-Amino-8-fluorohypoxanthine H amino acid CH3 S 2-Aminohypoxanthine H amino acid CH3 S 2-N-acetylguanine H amino acid CH3 S 4-N-acetylcytosine H amino acid CH3 S 6-N-acetyladenine H amino acid CH3 S 2-N-acetyl-8-fluoroguanine H amino acid CH3 S 4-N-acetyl-5-fluorocytosine H amino acid CH3 S 6-N-acetyl-2-fluoroadenine H amino acid CH3 S 6-N-acetyl-2, 8-difluoroadenine H amino acid CH3 S 6-N-acetyl-2-aminoadenine H amino acid CH3 S 6-N-acetyl-2-amino-8-fluoroadenine H amino acid CH3 S 2-N-acetylaminoadenine H amino acid CH3 S 2-N-acetylamino-8-fluoroadenine H amino acid CH3 S 2-N-acetylamino-8-fluorohypoxanthine H amino acid CH3 S 2-N-acetylaminohypoxanthine amino acid amino acid CH3 S Thymine amino acid amino acid CH3 S Uracil amino acid amino acid CH3 S Guanine amino acid amino acid CH3 S Cytosine amino acid amino acid CH3 S Adenine R2 R R X Base amino acid amino acid CH3 S Hypoxanthine amino acid amino acid CH3 S 5-Fluorouracil amino acid amino acid CH3 S 8-Fluoroguanine amino acid amino acid CH3 S 5-Fluorocytosine amino acid amino acid CH3 S 8-Fluoroadenine amino acid amino acid CH3 S 2-Fluoroadenine amino acid amino acid CH3 S 2, 8-Difluoroadenine amino acid amino acid CH3 S 2-Fluorohypoxanthine amino acid amino acid CH3 S 8-Fluorohypoxanthine amino acid amino acid CH3 S 2, 8-Difluorohypoxanthine amino acid amino acid CH3 S 2-Aminoadenine amino acid amino acid CH3 S 2-Amino-8-fluoroadenine amino acid amino acid CH3 S 2-Amino-8-fluorohypoxanthine amino acid amino acid CH3 S 2-Aminohypoxanthine amino acid amino acid CH3 S 2-N-acetylguanine amino acid amino acid CH3 S 4-N-acetylcytosine amino acid amino acid CH3 S 6-N-acetyladenine amino acid amino acid CH3 S 2-N-acetyl-8-fluoroguanine amino acid amino acid CH3 S 4-N-acetyl-5-fluorocytosine amino acid amino acid CH3 S 6-N-acetyl-2-fluoroadenine amino acid amino acid CH3 S 6-N-acetyl-2, 8-difluoroadenine amino acid amino acid CH3 S 6-N-acetyl-2-aminoadenine amino acid amino acid CH3 S 6-N-acetyl-2-amino-8-fluoroadenine amino acid amino acid CH3 S 2-N-acetylaminoadenine amino acid amino acid CH3 S 2-N-acetylamino-8-fluoroadenine amino acid amino acid CH3 S 2-N-acetylamino-8-fluorohypoxanthine amino acid amino acid CH3 S 2-N-acetylaminohypoxanthine amino acid H CH3 S Thymine amino acid H CH3 S Uracil amino acid H CH3 S Guanine amino acid H CH3 S Cytosine amino acid H CH3 S Adenine amino acid H CH3 S Hypoxanthine amino acid H CH3 S 5-Fluorouracil amino acid H CH3 S 8-Fluoroguanine amino acid H CH3 S 5-Fluorocytosine amino acid H CH3 S 8-Fluoroadenine amino acid H CH3 S 2-Fluoroadenine amino acid H CH3 S 2, 8-Difluoroadenine amino acid H CH3 S 2-Fluorohypoxanthine amino acid H CH3 S 8-Fluorohypoxanthine amino acid H CH3 S 2, 8-Difluorohypoxanthine amino acid H CH3 S 2-Aminoadenine amino acid H CH3 S 2-Amino-8-fluoroadenine amino acid H CH3 S 2-Amino-8-fluorohypoxanthine amino acid H CH3 S 2-Aminohypoxanthine amino acid H CH3 S 2-N-acetylguanine R 2 R3 R 6 X Base amino acid H CH3 S 4-N-acetylcytosine amino acid H CH3 S 6-N-acetyladenine amino acid H CH3 S 2-N-acetyl-8-fluoroguanine amino acid H CH3 S 4-N-acety1-5-fluorocytosine amino acid H CH3 S 6-N-acetyl-2-fluoroadenine amino acid H CH3 S 6-N-acetyl-2, 8-difluoroadenine amino acid H CH3 S 6-N-acetyl-2-aminoadenine amino acid H CH3 S 6-N-acetyl-2-amino-8-fluoroadenine amino acid H CH3 S 2-N-acetylaminoadenine amino acid H CH3 S 2-N-acetylamino-8-fluoroadenine amino acid H CH3 S 2-N-acetylamino-8-fluorohypoxanthine amino acid H CH3 S 2-N-acetylaminohypoxanthine amino acid acyl CH3 S Thymine amino acid acyl CH3 S Uracil amino acid acyl CH3 S Guanine amino acid acyl CH3 S Cytosine amino acid acyl CH3 S Adenine amino acid acyl CH3 S Hypoxanthine amino acid acyl CH3 S 5-Fluorouracil amino acid acyl CH3 S 8-Fluoroguanine amino acid acyl CH3 S 5-Fluorocytosine amino acid acyl CH3 S 8-Fluoroadenine amino acid acyl CH3 S 2-Fluoroadenine amino acid acyl CH3 S 2, 8-Difluoroadenine amino acid acyl CH3 S 2-Fluorohypoxanthine amino acid acyl CH3 S 8-Fluorohypoxanthine amino acid acyl CH3 S 2, 8-Difluorohypoxanthine amino acid acyl CH3 S 2-Aminoadenine amino acid acyl CH3 S 2-Amino-8-fluoroadenine amino acid acyl CH3 S 2-Amino-8-fluorohypoxanthine amino acid acyl CH3 S 2-Aminohypoxanthine amino acid acyl CH3 S 2-N-acetylguanine amino acid acyl CH3 S 4-N-acetylcytosine amino acid acyl CH3 S 6-N-acetyladenine amino acid acyl CH3 S 2-N-acetyl-8-fluoroguanine amino acid acyl CH3 S 4-N-acetyl-5-fluorocytosine amino acid acyl CH3 S 6-N-acetyl-2-fluoroadenine amino acid acyl CH3 S 6-N-acetyl-2, 8-difluoroadenine amino acid acyl CH3 S 6-N-acetyl-2-aminoadenine amino acid acyl CH3 S 6-N-acetyl-2-amino-8-fluoroadenine amino acid acyl CH3 S 2-N-acetylaminoadenine amino acid acyl CH3 S 2-N-acetylamino-8-fluoroadenine amino acid acyl CH3 S 2-N-acetylamino-8-fluorohypoxanthine amino acid acyl CH3 S 2-N-acetylaminohypoxanthine acyl H CF3 S Thymine acyl H CF3 S Uracil acyl H CF3 S Guanine R R R X Base acyl H CF3 S Cytosine acyl H CF3 S Adenine acyl H CF3 S Hypoxanthine acyl H CF3 S 5-Fluorouracil acyl H CF3 S 8-Fluoroguanine acyl H CF3 S 5-Fluorocytosine acyl H CF3 S 8-Fluoroadenine acyl H CF3 S 2-Fluoroadenine acyl H CF3 S 2, 8-Difluoroadenine acyl H CF3 S 2-Fluorohypoxanthine acyl H CF3 S 8-Fluorohypoxanthine acyl H CF3 S 2, 8-Difluorohypoxanthine acyl H CF3 S 2-Aminoadenine acyl H CF3 S 2-Amino-8-fluoroadenine acyl H CF3 S 2-Amino-8-fluorohypoxanthine acyl H CF3 S 2-Aminohypoxanthine acyl H CF3 S 2-N-acetylguanine acyl H CF3 S 4-N-acetylcytosine acyl H CF3 S 6-N-acetyladenine acyl H CF3 S 2-N-acetyl-8-fluoroguanine acyl H CF3 S 4-N-acetyl-5-fluorocytosine # acyl H CF3 S 6-N-acetyl-2-fluoroadenine acyl H CF3 S 6-N-acetyl-2, 8-difluoroadenine acyl H CF3 S 6-N-acetyl-2-aminoadenine acyl H CF3 S 6-N-acetyl-2-amino-8-fluoroadenine acyl H CF3 S 2-N-acetylaminoadenine acyl H CF3 S 2-N-acetylamino-8-fluoroadenine acyl H CF3 S 2-N-acetylamino-8-fluorohypoxanthine acyl H CF3 S 2-N-acetylaminohypoxanthine acyl acyl CF3 S Thymine acyl acyl CF3 S Uracil acyl acyl CF3 S Guanine acyl acyl CF3 S Cytosine acyl acyl CF3 S Adenine acyl acyl CF3 S Hypoxanthine acyl acyl CF3 S 5-Fluorouracil acyl acyl CF3 S 8-Fluoroguanine acyl acyl CF3 S 5-Fluorocytosine acyl acyl CF3 S 8-Fluoroadenine acyl acyl CF3 S 2-Fluoroadenine acyl acyl CF3 S 2, 8-Difluoroadenine acyl acyl CF3 S 2-Fluorohypoxanthine acyl acyl CF3 S 8-Fluorohypoxanthine acyl acyl CF3 S 2, 8-Difluorohypoxanthine acyl acyl CF3 S 2-Aminoadenine acyl acyl CF3 S 2-Amino-8-fluoroadenine acyl acyl CF3 S 2-Amino-8-fluorohypoxanthine R2 R3 R X Base acyl acyl CF3 S 2-Aminohypoxanthine acyl acyl CF3 S 2-N-acetylguanine acyl acyl CF3 S 4-N-acetylcytosine acyl acyl CF3 S 6-N-acetyladenine acyl acyl CF3 S 2-N-acetyl-8-fluoroguanine acyl acyl CF3 S 4-N-acetyl-5-fluorocytosine acyl acyl CF3 S 6-N-acetyl-2-fluoroadenine acyl acy1 CF3 S 6-N-acety1-2, 8-difluoroadenine acyl acyl CF3 S 6-N-acetyl-2-aminoadenine acyl acyl CF3 S 6-N-acetyl-2-amino-8-fluoroadenine acyl acyl CF3 S 2-N-acetylaminoadenine acyl acyl CF3 S 2-N-acetylamino-8-fluoroadenine acyl acyl CF3 S 2-N-acetylamino-8-fluorohypoxanthine acyl acyl CF3 S 2-N-acetylaminohypoxanthine acyl amino acid CF3 S Thymine acyl amino acid CF3 S Uracil acyl amino acid CF3 S Guanine acyl amino acid CF3 S Cytosine acyl amino acid CF3 S Adenine acyl amino acid CF3 S Hypoxanthine acyl amino acid CF3 S 5-Fluorouracil acyl amino acid CF3 S 8-Fluoroguanine acyl amino acid CF3 S 5-Fluorocytosine acyl amino acid CF3 S 8-Fluoroadenine acyl amino acid CF3 S 2-Fluoroadenine acyl amino acid CF3 S 2, 8-Difluoroadenine acyl amino acid CF3 S 2-Fluorohypoxanthine acyl amino acid CF3 S 8-Fluorohypoxanthine acyl amino acid CF3 S 2, 8-Difluorohypoxanthine acyl amino acid CF3 S 2-Aminoadenine acyl amino acid CF3 S 2-Amino-8-fluoroadenine acyl amino acid CF3 S 2-Amino-8-fluorohypoxanthine acyl amino acid CF3 S 2-Aminohypoxanthine acyl amino acid CF3 S 2-N-acetylguanine acyl amino acid CF3 S 4-N-acetylcytosine acyl amino acid CF3 S 6-N-acetyladenine acyl amino acid CF3 S 2-N-acetyl-8-fluoroguanine acyl amino acid CF3 S 4-N-acetyl-5-fluorocytosine acyl amino acid CF3 S 6-N-acetyl-2-fluoroadenine acyl amino acid CF3 S 6-N-acetyl-2, 8-difluoroadenine acyl amino acid CF3 S 6-N-acetyl-2-aminoadenine acyl amino acid CF3 S 6-N-acetyl-2-amino-8-fluoroadenine acyl amino acid CF3 S 2-N-acetylaminoadenine acyl amino acid CF3 S 2-N-acetylamino-8-fluoroadenine acyl amino acid CF3 S 2-N-acetylamino-8-fluorohypoxanthine acyl amino acid CF3 S 2-N-acetylaminohypoxanthine H acyl CF3 S Thymine R R R X Base H acyl CF3 S Uracil H acyl CF3 S Guanine H acyl CF3 S Cytosine H acyl CF3 S Adenine H acyl CF3 S Hypoxanthine H acyl CF3 S 5-Fluorouracil H acyl CF3 S 8-Fluoroguanine H acyl CF3 S 5-Fluorocytosine H acyl CF3 S 8-Fluoroadenine H acyl CF3 S 2-Fluoroadenine H acyl CF3 S 2, 8-Difluoroadenine H acyl CF3 S 2-Fluorohypoxanthine H acyl CF3 S 8-Fluorohypoxanthine H acyl CF3 S 2, 8-Difluorohypoxanthine H acyl CF3 S 2-Aminoadenine H acyl CF3 S 2-Amino-8-fluoroadenine H acyl CF3 S 2-Amino-8-fluorohypoxanthine H acyl CF3 S 2-Aminohypoxanthine H acyl CF3 S 2-N-acetylguanine H acyl CF3 S 4-N-acetylcytosine H acyl CF3 S 6-N-acetyladenine H acyl CF3 S 2-N-acetyl-8-fluoroguanine H acyl CF3 S 4-N-acetyl-5-fluorocytosine H acyl CF3 S 6-N-acetyl-2-fluoroadenine H acyl CF3 S 6-N-acetyl-2, 8-difluoroadenine H acyl CF3 S 6-N-acetyl-2-aminoadenine H acyl CF3 S 6-N-acetyl-2-amino-8-fluoroadenine H acyl CF3 S 2-N-acetylaminoadenine H acyl CF3 S 2-N-acetylamino-8-fluoroadenine H acyl CF3 S 2-N-acetylamino-8-fluorohypoxanthine H acyl CF3 S 2-N-acetylaminohypoxanthine H amino acid CF3 S Thymine H amino acid CF3 S Uracil H amino acid CF3 S Guanine H amino acid CF3 S Cytosine H amino acid CF3 S Adenine H amino acid CF3 S Hypoxanthine H amino acid CF3 S 5-Fluorouracil H amino acid CF3 S 8-Fluoroguanine H amino acid CF3 S 5-Fluorocytosine H amino acid CF3 S 8-Fluoroadenine H amino acid CF3 S 2-Fluoroadenine H amino acid CF3 S 2, 8-Difluoroadenine H amino acid CF3 S 2-Fluorohypoxanthine H amino acid CF3 S 8-Fluorohypoxanthine H amino acid CF3 S 2, 8-Difluorohypoxanthine H amino acid CF3 S 2-Aminoadenine R R R X Base H amino acid CF3 S 2-Amino-8-fluoroadenine H amino acid CF3 S 2-Amino-8-fluorohypoxanthine H amino acid CF3 S 2-Aminohypoxanthine H amino acid CF3 S 2-N-acetylguanine H amino acid CF3 S 4-N-acetylcytosine H amino acid CF3 S 6-N-acetyladenine H amino acid CF3 S 2-N-acetyl-8-fluoroguanine H amino acid CF3 S 4-N-acetyl-5-fluorocytosine H amino acid CF3 S 6-N-acetyl-2-fluoroadenine H amino acid CF3 S 6-N-acetyl-2, 8-difluoroadenine H amino acid CF3 S 6-N-acetyl-2-aminoadenine H amino acid CF3 S 6-N-acetyl-2-amino-8-fluoroadenine H amino acid CF3 S 2-N-acetylaminoadenine H amino acid CF3 S 2-N-acetylamino-8-fluoroadenine H amino acid CF3 S 2-N-acetylamino-8-fluorohypoxanthine H amino acid CF3 S 2-N-acetylaminohypoxanthine amino acid amino acid CF3 S Thymine amino acid amino acid CF3 S Uracil amino acid amino acid CF3 S Guanine amino acid amino acid CF3 S Cytosine amino acid amino acid CF3 S Adenine amino acid amino acid CF3 S Hypoxanthine amino acid amino acid CF3 S 5-Fluorouracil amino acid amino acid CF3 S 8-Fluoroguanine amino acid amino acid CF3 S 5-Fluorocytosine amino acid amino acid CF3 S 8-Fluoroadenine amino acid amino acid CF3 S 2-Fluoroadenine amino acid amino acid CF3 S 2, 8-Difluoroadenine amino acid amino acid CF3 S 2-Fluorohypoxanthine amino acid amino acid CF3 S 8-Fluorohypoxanthine amino acid amino acid CF3 S 2, 8-Difluorohypoxanthine amino acid amino acid CF3 S 2-Aminoadenine amino acid amino acid CF3 S 2-Amino-8-fluoroadenine amino acid amino acid CF3 S 2-Amino-8-fluorohypoxanthine amino acid amino acid CF3 S 2-Aminohypoxanthine amino acid amino acid CF3 S 2-N-acetylguanine amino acid amino acid CF3 S 4-N-acetylcytosine amino acid amino acid CF3 S 6-N-acetyladenine amino acid amino acid CF3 S 2-N-acetyl-8-fluoroguanine amino acid amino acid CF3 S 4-N-acetyl-5-fluorocytosine amino acid amino acid CF3 S 6-N-acetyl-2-fluoroadenine amino acid amino acid CF3 S 6-N-acetyl-2, 8-difluoroadenine amino acid amino acid CF3 S 6-N-acetyl-2-aminoadenine amino acid amino acid CF3 S 6-N-acetyl-2-amino-8-fluoroadenine amino acid amino acid CF3 S 2-N-acetylaminoadenine amino acid amino acid CF3 S 2-N-acetylamino-8-fluoroadenine amino acid amino acid CF3 S 2-N-acetylamino-8-fluorohypoxanthine R R R X Base amino acid amino acid CF3 S 2-N-acetylaminohypoxanthine amino acid H CF3 S Thymine amino acid H CF3 S Uracil amino acid H CF3 S Guanine amino acid H CF3 S Cytosine amino acid H CF3 S Adenine amino acid H CF3 S Hypoxanthine amino acid H CF3 S 5-Fluorouracil amino acid H CF3 S 8-Fluoroguanine amino acid H CF3 S S-Fluorocytosine amino acid H CF3 S 8-Fluoroadenine amino acid H CF3 S 2-Fluoroadenine amino acid H CF3 S 2, 8-Difluoroadenine amino acid H CF3 S 2-Fluorohypoxanthine amino acid H CF3 S 8-Fluorohypoxanthine amino acid H CF3 S 2, 8-Difluorohypoxanthine amino acid H CF3 S 2-Aminoadenine amino acid H CF3 S 2-Amino-8-fluoroadenine amino acid H CF3 S 2-Amino-8-fluorohypoxanthine amino acid H CF3 S 2-Aminohypoxanthine amino acid H CF3 S 2-N-acetylguanine amino acid H CF3 S 4-N-acetylcytosine amino acid H CF3 S 6-N-acetyladenine amino acid H CF3 S 2-N-acetyl-8-fluoroguanine amino acid H CF3 S 4-N-acetyl-5-fluorocytosine amino acid H CF3 S 6-N-acetyl-2-fluoroadenine amino acid H CF3 S 6-N-acetyl-2, 8-difluoroadenine amino acid H CF3 S 6-N-acetyl-2-aminoadenine amino acid H CF3 S 6-N-acetyl-2-amino-8-fluoroadenine amino acid H CF3 S 2-N-acetylaminoadenine amino acid H CF3 S 2-N-acetylamino-8-fluoroadenine amino acid H CF3 S 2-N-acetylamino-8-fluorohypoxanthine amino acid H CF3 S 2-N-acetylaminohwypoxanthine amino acid acyl CF3 S Thymine amino acid acyl CF3 S Uracil amino acid acyl CF3 S Guanine amino acid acyl CF3 S Cytosine amino acid acyl CF3 S Adenine amino acid acyl CF3 S Hypoxanthine amino acid acyl CF3 S 5-Fluorouracil amino acid acyl CF3 S 8-Fluoroguanine amino acid acyl CF3 S 5-Fluorocytosine amino acid acyl CF3 S 8-Fluoroadenine amino acid acyl CF3 S 2-Fluoroadenine amino acid acyl CF3 S 2, 8-Difluoroadenine amino acid acyl CF3 S 2-Fluorohypoxanthine amino acid acyl CF3 S 8-Fluorohypoxanthine R2 R3 R X Base amino acid acyl CF3 S 2, 8-Difluorohypoxanthine amino acid acyl CF3 S 2-Aminoadenine amino acid acyl CF3 S 2-Amino-8-fluoroadenine amino acid acyl CF3 S 2-Amino-8-fluorohypoxanthine amino acid acyl CF3 S 2-Aminohypoxanthine amino acid acyl CF3 S 2-N-acetylguanine amino acid acyl CF3 S 4-N-acetylcytosine amino acid acyl CF3 S 6-N-acetyladenine amino acid acyl CF3 S 2-N-acetyl-8-fluoroguanine amino acid acyl CF3 S 4-N-acetyl-5-fluorocytosine amino acid acyl CF3 S 6-N-acetyl-2-fluoroadenine amino acid acyl CF3 S 6-N-acetyl-2, 8-difluoroadenine amino acid acyl CF3 S 6-N-acetyl-2-aminoadenine amino acid acyl CF3 S 6-N-acetyl-2-amino-8-fluoroadenine amino acid acyl CF3 S 2-N-acetylaminoadenine amino acid acyl CF3 S 2-N-acetylamino-8-fluoroadenine amino acid acyl CF3 S 2-N-acetylamino-8-fluorohypoxanthine amino acid acyl CF3 S 2-N-acetylaminohypoxanthine acyl H CF3 O Thymine acyl H CF3 O Uracil acyl H CF3 O Guanine acyl H CF3 O Cytosine acyl H CF3 O Adenine acyl H CF3 0 Hypoxanthine acyl H CF3 0 5-Fluorouracil acyl H CF3 O 8-Fluoroguanine acyl H CF3 O 5-Fluorocytosine acyl H CF3 O 8-Fluoroadenine acyl H CF3 O 2-Fluoroadenine acyl H CF3 0 2, 8-Difluoroadenine acyl H CF3 O 2-Fluorohypoxanthine acyl H CF3 O 8-Fluorohypoxanthine acyl H CF3 O 2, 8-Difluorohypoxanthine acyl H CF3 O 2-Aminoadenine acyl H CF3 O 2-Amino-8-fluoroadenine acyl H CF3 O 2-Amino-8-fluorohypoxanthine ac 1 H CF3 O 2-Aminoh oxanthine acyl H CF3 O 2-N-acetylguanine acyl H CF3 O 4-N-acetylcytosine acyl H CF3 O 6-N-acetyladenine acyl H CF3 O 2-N-acetyl-8-fluoroguanine acyl H CF3 O 4-N-acetyl-5-fluorocytosine acyl H CF3 O 6-N-acetyl-2-fluoroadenine acyl H CF3 O 6-N-acetyl-2, 8-difluoroadenine acyl H CF3 O 6-N-acetyl-2-aminoadenine acyl H CF3 O 6-N-acetyl-2-amino-8-fluoroadenine acyl H CF3 O 2-N-acetylaminoadenine R2 R3 R6 X Base acyl H CF3 O 2-N-acetylamino-8-fluoroadenine acyl H CF3 O 2-N-acetylamino-8-fluorohypoxanthine acyl H CF3 0 2-N-acetylaminohypoxanthine acyl acyl CF3 O Thymine acyl acyl CF3 O Uracil acyl acyl CF3 O Guanine acyl acyl CF3 O Cytosine acyl acyl CF3 O Adenine acyl acyl CF3 O Hypoxanthine acyl acyl CF3 O 5-Fluorouracil acyl acyl CF3 O 8-Fluoroguanine acyl acyl CF3 O 5-Fluorocytosine acyl acyl CF3 O 8-Fluoroadenine acyl acyl CF3 O 2-Fluoroadenine acyl acyl CF3 O 2, 8-Difluoroadenine acyl acyl CF3 O 2-Fluorohypoxanthine acyl acyl CF3 O 8-Fluorohypoxanthine acyl acyl CF3 O 2, 8-Difluorohypoxanthine acyl acyl CF3 O 2-Aminoadenine acyl acyl CF3 O 2-Amino-8-fluoroadenine acyl acyl CF3 O 2-Amino-8-fluorohypoxanthine acyl acyl CF3 O 2-Aminohypoxanthine acyl acyl CF3 O 2-N-acetylguanine acyl acyl CF3 O 4-N-acetylcytosine acyl acyl CF3 O 6-N-acetyladenine acyl acyl CF3 O 2-N-acetyl-8-fluoroguanine acyl acyl CF3 O 4-N-acetyl-5-fluorocytosine acyl acyl CF3 O 6-N-acetyl-2-fluoroadenine acyl acyl CF3 O 6-N-acetyl-2, 8-difluoroadenine acyl acyl CF3 O 6-N-acetyl-2-aminoadenine acyl acyl CF3 O 6-N-acetyl-2-amino-8-fluoroadenine acyl acyl CF3 O 2-N-acetylaminoadenine acyl acyl CF3 O 2-N-acetylamino-8-fluoroadenine acyl acyl CF3 O 2-N-acetylamino-8-fluorohypoxanthine acyl acyl CF3 O 2-N-acetylaminohypoxanthine acyl amino acid CF3 O Thymine acyl amino acid CF3 O Uracil acyl amino acid CF3 O Guanine acyl amino acid CF3 O Cytosine acyl amino acid CF3 O Adenine acyl amino acid CF3 Hypoxanthine acyl amino acid CF3 O 5-Fluorouracil acyl amino acid CF3 O 8-Fluoroguanine acyl am ino acid CF3 O 5-Fluorocytosine acyl amino acid CF3 O 8-Fluoroadenine acyl amino acid CF3 O 2-Fluoroadenine acyl amino acid CF3 O 2, 8-Difluoroadenine R2 R R X Base acyl amino acid CF3 O 2-Fluorohypoxanthine acyl amino acid CF3 O 8-Fluorohypoxanthine acyl amino acid CF3 O 2, 8-Difluorohypoxanthine acyl amino acid CF3 O 2-Aminoadenine acYI amino acid CF3 O 2-Amino-8-fluoroadenine acyl amino acid CF3 O 2-Amino-8-fluorohypoxanthine acyl amino acid CF3 O 2-Aminohypoxanthine ac 1 amino acid CF3 O 2-N-acet 1 uanine ac 1 amino acid CFs O 4-N-acetylcytosine acyl amino acid CF3 O 6-N-acetyladenine acyl amino acid CF3 O 2-N-acetyl-8-fluoroguanine acyl amino acid CF3 O 4-N-acetyl-5-fluorocytosine w acyl amino acid CF3 O 6-N-acetyl-2-fluoroadenine acyl amino acid CF3 O 6-N-acetyl-2, 8-difluoroadenine acyl amino acid CF3 O 6-N-acetyl-2-aminoadenine acyl amino acid CF3 O 6-N-acetyl-2-amino-8-fluoroadenine acyl amino acid CF3 O 2-N-acetylarninoadenine acyl amino acid CF3 O 2-N-acetylamino-8-fluoroadenine acyl amino acid CF3 O 2-N-acetylamino-8-fluorohypoxanthine acyl amino acid CF3 O 2-N-acetylaminohypoxanthine H acyl CF3 O Thymine H acyl CF3 O Uracil H acyl CF3 O Guanine H acyl CF3 O Cytosine H acyl CF3 O Adenine H acyl CF3 O Hypoxanthine H acyl CF3 O 5-Fluorouracil H acyl CF3 O 8-Fluoroguanine H acyl CF3 O S-Fluorocytosine H ac 1 CF3 O 8-Fluoroadenine H acyl CF3 O 2-Fluoroadenine H acyl CF3 O 2, 8-Difluoroadenine H acyl CF3 O 2-Fluorohypoxanthine H acyl CF3 O 8-Fluorohypoxanthine H acyl CF3 O 2, 8-Difluorohypoxanthine H acyl CF3 0 2-Aminoadenine H acyl CF3 O 2-Amino-8-fluoroadenine H acyl CF3 O 2-Amino-8-fluorohypoxanthine H acyl CF3 O 2-Aminohypoxanthine H acyl CF3 O 2-N-acetylguanine H acyl CF3 O 4-N-acetylcytosine H acyl _ CF3 O 6-N-acetyladenine H acyl CF3 O 2-N-acetyl-8-fluoroguanine H acyl CF3 O 4-N-acetyl-5-fluorocytosine H acyl CF3 O 6-N-acetyl-2-fluoroadenine H acyl CF3 O 6-N-acetyl-2, 8-difluoroadenine H acyl CF3 O 6-N-acetyl-2-aminoadenine R2 R3 R6 X Base H acyl CF3 O 6-N-acetyl-2-amino-8-fluoroadenine H acyl CF3 O 2-N-acetylaminoadenine H acyl CF3 O 2-N-acetylamino-8-fluoroadenine H acyl CF3 O 2-N-acetylamino-8-fluorohypoxanthine H acyl CF3 O 2-N-acetylaminohypoxanthine H amino acid CF3 O Thymine H amino acid CF3 O Uracil H amino acid CF3 O Guanine H amino acid CF3 O Cytosine H amino acid CF3 O Adenine H amino acid CF3 O Hypoxanthine H amino acid CF3 O 5-Fluorouracil H amino acid CF3 O 8-Fluoroguanine H amino acid CF3 O 5-Fluorocytosine H amino acid CF3 O 8-Fluoroadenine H amino acid CF3 O 2-Fluoroadenine H amino acid CF3 O 2, 8-Difluoroadenine H amino acid CF3 O 2-Fluorohypoxanthine H amino acid CF3 O 8-Fluorohypoxanthine H amino acid CF3 O 2, 8-Difluorohypoxanthine H amino acid CF3 O 2-Aminoadenine H amino acid CF3 O 2-Amino-8-fluoroadenine H amino acid CF3 O 2-Amino-8-fluorohypoxanthine H amino acid CF3 O 2-Aminohypoxanthine H amino acid CF3 O 2-N-acetylguanine H amino acid CF3 O 4-N-acetylcytosine H amino acid CF3 O 6-N-acetyladenine H amino acid CF3 O 2-N-acetyl-8-fluoroguanine H amino acid CF3 O 4-N-acetyl-5-fluorocytosine H amino acid CF3 O 6-N-acetyl-2-fluoroadenine H amino acid CF3 O 6-N-acetyl-2, 8-difluoroadenine H amino acid CF3 O 6-N-acetyl-2-aminoadenine H amino acid CF3 O 6-N-acetyl-2-amino-8-fluoroadenine H amino acid CF3 O 2-N-acetylaminoadenine H amino acid CF3 O 2-N-acetylamino-8-fluoroadenine H amino acid CF3 O 2-N-acetylamino-8-fluorohypoxanthine H amino acid CF3 O 2-N-acetylaminohypoxanthine amino acid amino acid CF3 O Thymine amino acid amino acid CF3 O Uracil l amino acid amino acid CF3 O Guanine amino acid amino acid CF3 O Cytosine amino acid amino acid CF3 O Adenine amino acid amino acid CF3 O Hypoxanthine amino acid amino acid CF3 O 5-Fluorouracil amino acid amino acid CF3 O 8-Fluoroguanine amino acid amino acid CF3 O 5-Fluorocytosine amino acid amino acid CF3 O 8-Fluoroadenine R R R X Base amino acid amino acid CF3 O 2-Fluoroadenine amino acid amino acid CF3 O 2, 8-Difluoroadenine amino acid amino acid CF3 O 2-Fluorohypoxanthine amino acid amino acid CF3 O 8-Fluoroh oxanthine amino acid amino acid CF3 O 2, 8-Difluorohypoxanthine amino acid amino acid CF3 O 2-Aminoadenine amino acid amino acid CF3 O 2-Amino-8-fluoroadenine amino acid amino acid CF3 O 2-Amino-8-fluorohypoxanthine amino acid amino acid CF3 O 2-Aminohypoxanthine amino acid amino acid CF3 O 2-N-acetylguanine amino acid amino acid CF3 O 4-N-acetylcytosine amino acid amino acid CF3 O 6-N-acetyladenine amino acid amino acid CF3 O 2-N-acetyl-8-fluoroguanine amino acid amino acid CF3 O 4-N-acetyl-5-fluorocytosine amino acid amino acid CF3 O 6-N-acetyl-2-fluoroadenine amino acid amino acid CF3 O 6-N-acetyl-2, 8-difluoroadenine amino acid amino acid CF3 O 6-N-acetyl-2-aminoadenine amino acid amino acid CF3 O 6-N-acetyl-2-amino-8-fluoroadenine amino acid amino acid CF3 O 2-N-acetylaminoadenine amino acid amino acid CF3 O 2-N-acetylamino-8-fluoroadenine amino acid amino acid CF3 O 2-N-acetylamino-8-fluorohypoxanthine amino acid amino acid CF3 Q 2-N-acetylaminohypoxanthine amino acid H CF3 O Thymine amino acid H CF3 O Uracil amino acid H CF3 O Guanine amino acid H CF3 O Cytosine amino acid H CF3 O Adenine amino acid H CF3 O Hypoxanthine amino acid H CF3 O 5-Fluorouracil amino acid H CF3 O 8-Fluoroguanine amino acid H CF3 O 5-Fluorocytosine amino acid H CF3 O 8-Fluoroadenine amino acid H CF3 O 2-Fluoroadenine amino acid H CF3 O 2, 8-Difluoroadenine amino acid H CF3 O 2-Fluorohypoxanthine amino acid H CF3 O 8-Fluorohypoxanthine amino acid H CF3 O 2, 8-Difluorohypoxanthine amino acid H CF3 O 2-Aminoadenine amino acid H CF3 O 2-Amino-8-fluoroadenine amino acid H CF3 O 2-Amino-8-fluorohypoxanthine amino acid H CF3 O 2-Aminohypoxanthine amino acid H CF3 O 2-N-acetylguanine amino acid H CF3 O 4-N-acetylcytosine amino acid H CF3 O 6-N-acetyladenine amino acid H CF3 O 2-N-acetyl-8-fluoroguanine amino acid H CF3 O 4-N-acetyl-5-fluorocytosine amino acid H CF3 O 6-N-acetyl-2-fluoroadenine R R R X Base amino acid H CF3 O 6-N-acetyl-2, 8-difluoroadenine amino acid H CF3 O 6-N-acetyl-2-aminoadenine amino acid H CF3 O 6-N-acetyl-2-amino-8-fluoroadenine amino acid H CF3 O 2-N-acetylaminoadenine amino acid H CF3 O 2-N-acetylamino-8-fluoroadenine amino acid H CF3 O 2-N-acetylamino-8-fluorohypoxanthine amino acid H CF3 O 2-N-acetylaminohypoxanthine amino acid acyl CF3 O Thymine amino acid acyl CF3 O Uracil amino acid acyl CF3 O Guanine amino acid acyl CF3 O Cytosine amino acid acyl CF3 O Adenine amino acid acyl CF3 O Hypoxanthine amino acid ac 1 CF3 O S-Fluorouracil amino acid acyl CF3 O 8-Fluoroguanine amino acid acyl CF3 O 5-Fluorocytosine amino acid acyl CF3 O 8-Fluoroadenine amino acid acyl CF3 O 2-Fluoroadenine amino acid acyl CF3 O 2, 8-Difluoroadenine amino acid acyl CF3 O 2-Fluorohypoxanthine amino acid acyl CF3 O 8-Fluorohypoxanthine amino acid acyl CF3 O 2, 8-Difluorohypoxanthine amino acid acyl CF3 O 2-Aminoadenine amino acid acyl CF3 O 2-Amino-8-fluoroadenine am ino acid acyl CF3 O 2-Amino-8-fluorohypoxanthine amino acid acyl CF3 O 2-Aminohypoxanthine amino acid acyl CF3 O 2-N-acetylguanine amino acid acy1 CF3 O 4-N-acetylcytosine amino acid acyl CF3 O 6-N-acetyladenine amino acid acyl CF3 O 2-N-acetyl-8-fluoroguanine amino acid acyl CF3 O 4-N-acetyl-5-fluorocytosine amino acid acyl CF3 O 6-N-acetyl-2-fluoroadenine amino acid acyl CF3 O 6-N-acetyl-2, 8-difluoroadenine amino acid aceI CF3 O 6-N-aceteI-2-aminoadenine amino acid acyl CF3 O 6-N-acetyl-2-amino-8-fluoroadenine amino acid acyl CF3 O 2-N-acetylaminoadenine amino acid acyl CF3 O 2-N-acetylamino-8-fluoroadenine amino acid acyl CF3 O 2-N-acetylamino-8-fluorohypoxanthine amino acid acyl CF3 O 2-N-acetylaminohypoxanthine Table 4 RZ R6 X Base acyl CH3 O Thymine acyl CH3 O Uracil acyl CH3 O Guanine acyl CH3 O Cytosine acyl = CH3 X O Adenine acyl CH3 Hypoxanthine acyl CH3 O 5-Fluorouracil acyl CH3 O 8-Fluoroguanine acyl CH3 O 5-Fluorocytosine acyl CH3 O 8-Fluoroadenine acyl CH3 O 2-Fluoroadenine acyl CH3 O 2, 8-Difluoroadenine acyl CH3 O 2-Fluorohypoxanthine acyl CH3 X O 08-Fluorohypoxanthine X acyl CH3 O 2, 8-Difluorohypoxanthine acyl CH3 O 2-Aminoadenine acyl CH3 s O 2-Amino-8-fluoroadenine acyl CH3 O 2-Amino-8-fluorohypoxanthine acyl CH3 O 2-Aminohypoxanthine acyl CH3 O 2-N-acetylguanine acyl CH3 O 4-N-acetylcytosine acyl CH3 O 6-N-acetyladenine acyl CH3 O 2-N-acetyl-8-fluoroguanine acyl CH3 O 4-N-acetyl-5-fluorocytosine acyl CH3 O 6-N-acetyl-2-fluoroadenine acyl CH3 O 6-N-acetyl-2, 8-difluoroadenine acyl CH3 O 6-N-acetyl-2-aminoadenine acyl CH3 O 6-N-acetyl-2-amino-8-fluoroadenine acyl CH3 O 2-N-acetylaminoadenine acyl CH3 O 2-N-acetylamino-8-fluoroadenine acyl CH3 O 2-N-acetylamino-8-fluorohypoxanthine acyl CH3 O 2-N-acetylaminohypoxanthine amino acid CH3 O Thymine amino acid CH3 O Uracil amino acid CH3 O Guanine amino acid CH3 O Cytosine amino acid CH3 O Adenine amino acid CH3 Hypoxanthine amino acid CH3 O 5-Fluorouracil amino acid CH3 O 8-Fluoroguanine amino acid CH3 O 5-Fluorocytosine amino acid CH3 O 8-Fluoroadenine amino acid CH3 O 2-Fluoroadenine amino acid CH3 0 2, 8-Difluoroadenine R R X Base amino acid CH3 O 2-Fluorohypoxanthine amino acid CH3 O 8-Fluorohypoxanthine amino acid CH3 O 2, 8-Difluorohypoxanthine amino acid CH3 O 2-Aminoadenine amino acid CH3 O 2-Amino-8-fluoroadenine amino acid CH3 O 2-Amino-8-fluorohypoxanthine amino acid CH3 O 2-Aminohypoxanthine amino acid CH3 O 2-N-acetylguanine amino acid CH3 O 4-N-acetylcytosine amino acid CH3 O 6-N-acetyladenine amino acid CH3 O 2-N-acetyl-8-fluoroguanine amino acid CH3 O 4-N-acetyl-5-fluorocytosine amino acid CH3 O 6-N-acetyl-2-fluoroadenine amino acid CH3 O 6-N-acetyl-2, 8-difluoroadenine amino acid CH3 O 6-N-acetyl-2-aminoadenine amino acid CH3 O 6-N-acetyl-2-amino-8-fluoroadenine amino acid CH3 O 2-N-acetylaminoadenine amino acid CH3 O 2-N-acetylamino-8-fluoroadenine amino acid CH3 O 2-N-acetylamino-8-fluorohypoxanthine amino acid CH3 O 2-N-acetylaminohypoxanthine acyl CH3 S Thymine acyl CH3 S Uracil acyl CH3 S Guanine acyl CH3 S Cytosine acyl CH3 S Adenine acyl CH3 S Hypoxanthine acyl CH3 S 5-Fluorouracil acyl CH3 S 8-Fluoroguanine acyl CH3 S 5-Fluorocytosine acyl CH3 S 8-Fluoroadenine acyl CH3 S 2-Fluoroadenine acyl CH3 S 2, 8-Difluoroadenine acyl CH3 S 2-Fluorohypoxanthine acyl CH3 S 8-Fluorohypoxanthine acyl CH3 S 2, 8-Difluorohypoxanthine acyl CH3 S 2-Aminoadenine acyl CH3 S 2-Amino-8-fluoroadenine acyl CH3 S 2-Amino-8-fluorohypoxanthine acyl CH3 S 2-Aminohypoxanthine acyl CH3 S 2-N-acetylguanine acyl CH3 S 4-N-acetylcytosine acyl CH3 S 6-N-acetyladenine acyl CH3 S 2-N-acetyl-8-fluoroguanine acyl CH3 S 4-N-acetyl-5-fluorocytosine acyl CH3 S 6-N-acetyl-2-fluoroadenine acyl CH3 S 6-N-acetyl-2, 8-difluoroadenine R2 R6 X Base acyl CH3 S 6-N-acetyl-2-aminoadenine acyl CH3 S 6-N-acetyi-2-amino-8-fluoroadenine acyl CH3 S 2-N-acetylaminoadenine acyl CH3 S 2-N-acetylamino-8-fluoroadenine acyl CH3 S 2-N-acetylamino-8-fluorohypoxanthine acyl CH3 S 2-N-acetylaminohypoxanthine amino acid CH3 S Thymine amino acid CH3 S Uracil amino acid CH3 S Guanine amino acid CH3 S Cytosine amino acid CH3 S Adenine amino acid CH3 S Hypoxanthine amino acid CH3 S 5-Fluorouracil amino acid CH3 S 8-Fluoroguanine amino acid CH3 S 5-Fluorocytosine amino acid CH3 S 8-Fluoroadenine amino acid CH3 S 2-Fluoroadenine amino acid CH3 S 2, 8-Difluoroadenine amino acid CH3 S 2-Fluorohypoxanthine amino acid CH3 S 8-Fluorohypoxanthine amino acid CH3 S 2, 8-Difluorohypoxanthine amino acid CH3 S 2-Aminoadenine amino acid CH3 S 2-Amino-8-fluoroadenine amino acid CH3 S 2-Amino-8-fluorohypoxanthine amino acid CH3 S 2-Aminohypoxanthine amino acid CH3 S 2-N-acetylguanine amino acid CH3 S 4-N-acetylcytosine amino acid CH3 S 6-N-acetyladenine amino acid CH3 S 2-N-acetyl-8-fluoroguanine amino acid CH3 S 4-N-acetyl-5-fluorocytosine amino acid CH3 S 6-N-acetyl-2-fluoroadenine amino acid CH3 S 6-N-acetyl-2, 8-difluoroadenine amino acid CH3 S 6-N-acetyl-2-aminoadenine amino acid CH3 S 6-N-acetyl-2-amino-8-fluoroadenine amino acid CH3 S 2-N-acetylaminoadenine amino acid CH3 S 2-N-acetylamino-8-fluoroadenine amino acid CH3 S 2-N-acetylamino-8-fluorohypoxanthine amino acid CH3 S 2-N-acetylaminohypoxanthine acyl CF3 O Thymine acyl CF3 O Uracil acyl CF3 O Guanine acyl CF3 O Cytosine acyl CF3 O Adenine acyl CF3 O Hypoxanthine acyl CF3 O 5-Fluorouracil acyl CF3 O 8-Fluoroguanine R R6 X Base acyl CF3 O 5-Fluorocytosine acyl CF3 O 8-Fluoroadenine acyl CF3 O 2-Fluoroadenine acyl CF3 O 2, 8-Difluoroadenine acyl CF3 O 2-Fluorohypoxanthine acyl CF3 O 8-Fluorohypoxanthine acyl CF3 O 2, 8-Difluorohypoxanthine acyl CF3 O 2-Aminoadenine acyl CF3 O 2-Amino-8-fluoroadenine acyl CF3 O 2-Amino-8-fluorohypoxanthine acyl CF3 O 2-Aminohypoxanthine acyl CF3 O 2-N-acetylguanine acyl CF3 O 4-N-acetylcytosine acyl CF3 O 6-N-acetyladenine acyl CF3 O 2-N-acetyl-8-fluoroguanine acyl CF3 O 4-N-acetyl-5-fluorocytosine acyl CF3 O 6-N-acetyl-2-fluoroadenine acyl CF3 O 6-N-acetyl-2, 8-difluoroadenine acyl CF3 O 6-N-acetyl-2-aminoadenine acyl CF3 O 6-N-acetyl-2-amino-8-fluoroadenine acyl CF3 O 2-N-acetylaminoadenine acyl CF3 O 2-N-acetylamino-8-fluoroadenine acyl CF3 O 2-N-acetylamino-8-fluorohypoxanthine acyl CF3 O 2-N-acetylaminohypoxanthine amino acid CF3 O Thymine amino acid CF3 O Uracil amino acid CF3 O Guanine amino acid CF3 O Cytosine amino acid CF3 O Adenine amino acid CF3 O Hypoxanthine amino acid CF3 O 5-Fluorouracil amino acid CF3 O 8-Fluoroguanine amino acid CF3 O 5-Fluorocytosine amino acid CF3 O 8-Fluoroadenine amino acid CF3 O 2-Fluoroadenine amino acid CF3 O 2, 8-Difluoroadenine amino acid CF3 uorohypoxanthine amino acid CF3 O 8-Fluorohypoxanthine amino acid CF3 O 2, 8-Difluorohypoxanthine amino acid CF3 O 2-Aminoadenine amino acid CF3 O 2-Amino-8-fluoroadenine amino acid CF3 O 2-Amino-8-fluorohypoxanthine amino acid CF3 O 2-Aminohypoxanthine amino acid CF3 O 2-N-acetylguanine amino acid CF3 O'4-N-acetylcytosine amino acid CF3 0 6-N-acetyladenine RZ R6 X Base amino acid CF3 O 2-N-acetyl-8-fluoroguanine amino acid CF3 O 4-N-acetyl-5-fluorocytosine amino acid CF3 O 6-N-acetyl-2-fluoroadenine amino acid CF3 O 6-N-acetyl-2, 8-difluoroadenine amino acid CF3 O 6-N-acetyl-2-aminoadenine amino acid CF3 O 6-N-acetyl-2-amino-8-fluoroadenine amino acid CF3 O 2-N-acetylaminoadenine amino acid CF3 O 2-N-acetylamino-8-fluoroadenine amino acid CF3 O 2-N-acetylamino-8-fluorohypoxanthine amino acid CF3 O 2-N-acetylaminohypoxanthine acyl CF3 S Thymine acyl CF3 S Uracil acyl CF3 S Guanine acyl CF3 S Cytosine acyl CF3 S Adenine acyl CF3 S Hypoxanthine acyl CF3 S 5-Fluorouracil acyl CF3 S 8-Fluoroguanine acyl CF3 S 5-Fluorocytosine acyl CF3 S 8-Fluoroadenine acyl CF3 S 2-Fluoroadenine acyl CF3 S 2, 8-Difluoroadenine acyl CF3 S 2-Fluorohypoxanthine acyl CF3 S 8-Fluorohypoxanthine acyl CF3 S 2, 8-Difluorohypoxanthine acyl CF3 S 2-Aminoadenine acyl CF3 S 2-Amino-8-fluoroadenine acyl CF3 S 2-Amino-8-fluorohypoxanthine acyl CF3 S 2-Aminohypoxanthine acyl CF3 S 2-N-acetylguanine acyl CF3 S 4-N-acetylcytosine acyl CF3 S 6-N-acetyladenine acyl CF3 S 2-N-acetyl-8-fluoroguanine acyl CF3 S 4-N-acetyl-5-fluorocytosine acyl CF3 S 6-N-acetyl-2-fluoroadenine acyl CF3 S 6-N-acetyl-2, 8-difluoroadenine acyl CF3 S 6-N-acetyl-2-aminoadenine acyl CF3 S 6-N-acetyl-2-amino-8-fluoroadenine acyl CF3 S 2-N-acetylaminoadenine acyl CF3 S 2-N-acetylamino-8-fluoroadenine acyl CF3 S 2-N-acetylamino-8-fluorohypoxanthine acyl CF3 S 2-N-acetylaminohypoxanthine amino acid CF3 S Thymine amino acid CF3 S Uracil amino acid CF3 S Guanine amino acid CF3 S Cytosine R2 R6 X Base amino acid CF3 S Adenine amino acid CF3 S Hypoxanthine amino acid CF3 S 5-Fluorouracil amino acid CF3 S 8-Fluoroguanine amino acid CF3 S 5-Fluorocytosine amino acid CF3 S 8-Fluoroadenine amino acid CF3 S 2-Fluoroadenine amino acid CF3 S 2, 8-Difluoroadenine amino acid CF3 S 2-Fluorohypoxanthine amino acid CF3 S 8-Fluorohypoxanthine amino acid CF3 S 2, 8-Difluorohypoxanthine amino acid CF3 S 2-Aminoadenine amino acid CF3 S 2-Amino-8-fluoroadenine amino acid CF3 S 2-Amino-8-fluorohypoxanthine amino acid CF3 S 2-Aminohypoxanthine amino acid CF3 S 2-N-acetylguanine amino acid CF3 S 4-N-acetylcytosine amino acid CF3 S 6-N-acetyladenine amino acid CF3 S 2-N-acetyl-8-fluoroguanine amino acid CF3 S 4-N-acetyl-5-fluorocytosine amino acid CF3 S 6-N-acetyl-2-fluoroadenine am ino acid CF3 S 6-N-acetyl-2, 8-difluoroadenine amino acid CF3 S 6-N-acetyl-2-aminoadenine amino acid CF3 S 6-N-acetyl-2-amino-8-fluoroadenine amino acid CF3 S 2-N-acetylaminoadenine amino acid CF3 S 2-N-acetylamino-8-fluoroadenine amino acid CF3 S 2-N-acetylamino-8-fluorohypoxanthine amino acid CF3 S 2-N-acetylaminohypoxanthine Table 5 R2 R6 X Base amino acid CH3 O Thymine amino acid CH3 O Uracil amino acid CH3 O Guanine amino acid CH3 O Cytosine amino acid CH3 O Adenine amino acid CH3 O Hypoxanthine amino acid CH3 O 5-Fluorouracil amino acid CH3 O 8-Fluoroguanine amino acid CH3 O 5-Fluorocvtosine # amino acid CH3 O 8-Fluoroadenine amino acid CH3 O 2-Fluoroadenine amino acid CH3 O 2, 8-Difluoroadenine amino acid CH3 O 2-FluorohvDoxanthine amino acid CH3 O 8-Fluorohypoxanthine amino acid CH3 O 2, 8-Difluorohypoxanthine amino acid CH3 O 2-Aminoadenine amino acid CH3 O 2-Amino-8-fluoroadenine amino acid CH3 O 2-Amino-8-fluorohypoxanthine amino acid CH3 O 2-Aminohypoxanthine amino acid CH3 O 2-N-acetylguanine amino acid CH3 O 4-N-acetylcytosine amino acid CH3 O 6-N-acetyladenine amino acid CH3 O 2-N-acetyl-8-fluoroguanine amino acid CH3 O 4-N-acetyl-5-fluorocytosine amino acid CH3 O 6-N-acetyl-2-fluoroadenine amino acid CH3 O 6-N-acetyl-2, 8-difluoroadenine amino acid CH3 O 6-N-acetyl-2-aminoadenine amino acid CH3 O 6-N-acetyl-2-amino-8-fluoroadenine amino acid CH3 O 2-N-acetylaminoadenine amino acid CH3 O 2-N-acetylamino-8-fluoroadenine amino acid CH3 O 2-N-acetylamino-8-fluorohypoxanthine amino acid CH3 O 2-N-acetylaminohypoxanthine amino acid CH3 S Thymine amino acid CH3 S Uracil amino acid CH3 S Guanine amino acid CH3 S Cytosine amino acid CH3 S Adenine amino acid CH3 S Hypoxanthine amino acid CH3 S 5-Fluorouracil amino acid CH3 S 8-Fluoroguanine amino acid CH3 S 5-Fluorocytosine amino acid CH3 S 8-Fluoroadenine amino acid CH3 S 2-Fluoroadenine amino acid CH3 S 2, 8-Difluoroadenine amino acid CH3 S 2-Fluorohypoxanthine R2 R6 X Base amino acid CH3 S 8-Fluorohypoxanthine amino acid CH3 S 2, 8-Difluorohypoxanthine amino acid CH3 S 2-Aminoadenine amino acid CH3 S 2-Amino-8-fluoroadenine amino acid CH3 S 2-Amino-8-fluorohypoxanthine amino acid CH3 S 2-Aminohypoxanthine amino acid CH3 S 2-N-acetylguanine amino acid CH3 S 4-N-acetylcytosine amino acid CH3 S 6-N-acetyladenine amino acid CH3 S 2-N-acetyl-8-fluoroguanine amino acid CH3 S 4-N-acetyl-5-fluorocytosine amino acid CH3 S 6-N-acetyl-2-fluoroadenine amino acid CH3 S 6-N-acetyl-2, 8-difluoroadenine amino acid CH3 S 6-N-acetyl-2-arninoadenine amino acid CH3 S 6-N-acetyl-2-amino-8-fluoroadenine amino acid CH3 S 2-N-acetylaminoadenine amino acid CH3 S 2-N-acetylamino-8-fluoroadenine amino acid CH3 S 2-N-acetylamino-8-fluorohypoxanthine amino acid CH3 S 2-N-acetylaminohypoxanthine amino acid CF3 O Thymine amino acid CF3 O Uracil amino acid CF3 O Guanine amino acid CF3 O Cytosine amino acid CF3 O Adenine amino acid CF3 0 Hypoxanthine f A amino acid CF3 O 5-Fluorouracil amino acid CF3 O 8-Fluoroguanine amino acid CF3 O 5-Fluorocytosine amino acid CF3 O 8-Fluoroadenine amino acid CF3 O 2-Fluoroadenine amino acid CF3 O 2, 8-Difluoroadenine amino acid CF3 O 2-Fluorohypoxanthine amino acid CF3 O 8-Fluorohypoxanthine amino acids30 2, 8-Difluorohypoxanthine amino acid CF3 O 2-Aminoadenine amino acid CF3 O 2-Amino-8-fluoroadenine amino acid CF3 O 2-Amino-8-fluorohypoxanthine amino acid CF3 O 2-Aminohypoxanthine r amino acid CF3 O 2-N-acetylguanine O amino acid CF3 O 4-N-acetylcytosine amino acid CF3 O 6-N-acetyladenine amino acid CF3 O 2-N-acetyl-8-fluoroguanine amino acid _ CF3 H O 4-N-acetyl-S-fluorocytosine amino acid CF3 O 6-N-acetyl-2-fluoroadenine amino acid CF3 O 6-N-acetyl-2, 8-difluoroadenine amino acid CF3 O 6-N-acetyl-2-aminoadenine amino acid CF3 O 6-N-acetyl-2-amino-8-fluoroadenine R2 R6 X Base amino acid CF3 O 2-N-acetylaminoadenine amino acid CF3 O 2-N-acetylamino-8-fluoroadenine amino acid CF3 O 2-N-acetylamino-8-fluorohypoxanthine amino acid CF3 O 2-N-acetylaminohypoxanthine amino acid CF3 S Thymine amino acid CF3 S Uracil amino acid CF3 S Guanine amino acid CF3 S Cytosine amino acid CF3 S Adenine amino acid CF3 S Hypoxanthine amino acid CF3 S 5-Fluorouracil amino acid CF3 S 8-Fluoroguanine amino acid CF3 S 5-Fluorocytosine amino acid CF3 S 8-Fluoroadenine amino acid CF3 S 2-Fluoroadenine amino acid CF3 S 2, 8-Difluoroadenine amino acid CF3 S 2-FluorohvDoxanthine amino acid CF3 S 8-Fluorohypoxanthine amino acid CF3 S 2, 8-Difluorohypoxanthine amino acid CF3 S 2-Aminoadenine amino acid CF3 S 2-Amino-8-fluoroadenine amino acid CF3 S 2-Amino-8-fluorohypoxanthine amino acid CF3 S 2-Aminohypoxanthine amino acid CF3 S 2-N-acetylguanine amino acid CF3 S 4-N-acetylcytosine amino acid CF3 S 6-N-acetyladenine amino acid CF3 S 2-N-acetyl-8-fluoroguanine amino acid CF3 S 4-N-acetyl-5-fluorocytosine amino acid CF3 S 6-N-acetyl-2-fluoroadenine amino acid CF3 S 6-N-acetyl-2, 8-difluoroadenine amino acid CF3 S 6-N-acetyl-2-aminoadenine amino acid CF3 S 6-N-acetyl-2-amino-8-fluoroadenine amino acid CF3 S 2-N-acetylaminoadenine amino acid CF3 S 2-N-acetylamino-8-fluoroadenine amino acid CF3 S 2-N-acetylamino-8-fluorohypoxanthine amino acid CF3 S 2-N-acetylaminohypoxanthine acyl CH3 O Thymine acyl CH3 O Uracil acyl CH3 O Guanine acyl CH3 O Cytosine acyl CH3 O Adenine acyl CH3 O Hypoxanthine acyl CH3 O 5-Fluorouracil acyl CH3 O 8-Fluoroguanine acyl CH3 O 5-Fluorocytosine acyl CH3 O 8-Fluoroadenine acyl CH3 O 2-Fluoroadenine R2 R6 X Base acyl CH3 O 2, 8-Difluoroadenine acyl CH3 O 2-Fluorohypoxanthine acyl CH3 O 8-Fluorohypoxanthine acyl CH3 O 2, 8-Difluorohypoxanthine acyl CH3 O 2-Aminoadenine acyl CH3 O 2-Amino-8-fluoroadenine acyl CH3 O 2-Amino-8-fluorohypoxanthine acyl CH3 O 2-Aminohypoxanthine acyl CH3 O 2-N-acetylguanine acyl CH3 O 4-N-acetylcytosine acyl CH3 O 6-N-acetyladenine acyl CH3 O 2-N-acetyl-8-fluoroguanine acyl CH3 O 4-N-acetyl-5-fluorocytosine acyl CH3 O 6-N-acetyl-2-fluoroadenine acyl CH3 O 6-N-acetyl-2, 8-difluoroadenine acyl CH3 O 6-N-acetyl-2-aminoadenine acyl CH3 O 6-N-acetyl-2-amino-8-fluoroadenine acyl CH3 O 2-N-acetylaminoadenine acyl CH3 O 2-N-acetylamino-8-fluoroadenine acyl CH3 O 2-N-acetylamino-8-fluorohypoxanthine acyl CH3 O 2-N-acetylaminohypoxanthine acyl CH3 S Thymine acyl CH3 S Uracil acyl CH3 S Guanine acyl CH3 S Cytosine acyl CH3 S Adenine acyl CH3 S Hypoxanthine acyl CH3 S 5-Fluorouracil acyl CH3 S 8-Fluoroguanine acyl CH3 S 5-Fluorocytosine acyl CH3 S 8-Fluoroadenine acyl CH3 S 2-Fluoroadenine acyl CH3 S 2, 8-Difluoroadenine acyl CH3 S 2-Fluorohypoxanthine acyl CH3 S 8-Fluorohypoxanthine acyl CH3 S 2, 8-Difluorohypoxanthine acyl CH3 S 2-Aminoadenine acyl CH3 S 2-Amino-8-fluoroadenine acyl CH3 S 2-Amino-8-fluorohypoxanthine acyl CH3 S _ w acyl CH3 S 2-N-acetylguanine acyl CH3 S 4-N-acetylcytosine acyl CH3 S 6-N-acetyladenine acyl CH3 S 2-N-acetyl-8-fluoroguanine acyl CH3 S 4-N-acetyl-5-fluorocytosine acyl CH3 _ S 6-N-acetyl-2-fluoroaden i ne acyl CH3 S 6-N-acetyl-2, 8-difluoroadenine R R X Base acyl CH3 S 6-N-acetyl-2-aminoadenine acyl CH3 S 6-N-acetyl-2-amino-8-fluoroadenine acyl CH3 S 2-N-acetylaminoadenine acyl CH3 S 2-N-acetylamino-8-fluoroadenine acyI CH3 S 2-N-acetylamino-8-fluorohypoxanthine acyl CH3 S 2-N-acetylaminohypoxanthine acyl CF3 O Thymine acyl CF3 O Uracil acyl CF3 O Guanine acyl CF3 O Cytosine acyl CF3 O Adenine acyl CF3 O Hypoxanthine acyl CF3 O 5-Fluorouracil acyl CF3 O 8-Fluoroguanine acyl CF3 O 5-Fluorocytosine acyl CF3 O 8-Fluoroadenine acyl CF3 O 2-Fluoroadenine acyl CF3 O 2, 8-Difluoroadenine acyl CF3 O 2-Fluorohypoxanthine acyl CF3 O 8-Fluorohypoxanthine acy ! CF30 2, 8-Difluorohypoxanthine acyl CF3 O 2-Aminoadenine acyl CF3 O 2-Amino-8-fluoroadenine acyl CF3 O 2-Amino-8-fluorohypoxanthine acyl CF3 O 2-Aminohypoxanthine acyl CF3 O 2-N-acetylguanine acyl CF3 O 4-N-acetylcytosine acyl CF3 O 6-N-acetyladenine acyl CF3 O 2-N-acetyl-8-fluoroguanine acyI CF3 O 4-N-acetyl-S-fluorocytos ine acyl CF3 O 6-N-acetyl-2-fluoroadenine acyl CF3 O 6-N-acetyl-2, 8-difluoroadenine acyl CF3 O 6-N-acetyl-2-aminoadenine acyl CF3 O 6-N-acetyl-2-amino-8-fluoroadenine acyl CF3 O 2-N-acetylaminoadenine acyI CF3 O 2-N-acetylamino-8-fluoroadenine acyl CF3 O 2-N-acetylamino-8-fluorohypoxanthine acyl CF3 O 2-N-acetylaminohypoxanthine acyl CF3 S Thymine acyl CF3 S Uracil acyl CF3 S Guanine acyl CF3 S Cytosine acyl CF3 S Adenine acyl CF3 S Hypoxanthine acyl CF3 S 5-Fluorouracil acyl CF3 S 8-Fluoroguanine acyl CF3 S 5-Fluorocytosine R R6 X Base acvl CF3 S 8-Fluoroadenine acyl CF3 S 2-Fluoroadenine acyl CF3 S 2, 8-Difluoroadenine acyl CF3 S 2-Fluorohypoxanthine acyl CF3 S 8-Fluorohypoxanthine acyl CF3 S 2, 8-Difluorohypoxanthine acyl CF3 S 2-Aminoadenine acyl CF3 S 2-Amino-8-fluoroadenine acyl CF3 S 2-Amino-8-fluorohypoxanthine acyl CF3 S 2-Aminohypoxanthine acyl CF3 S 2-N-acetylguanine acyl CF3 S 4-N-acetylcytosine acyl CF3 S 6-N-acetyladenine acyl CF3 S 2-N-acetyl-8-fluoroguanine acyl CF3 S 4-N-acetyl-5-fluorocytosine acyl CF3 S 6-N-acetyl-2-fluoroadenine acyl CF3 S 6-N-acetyl-2, 8-difluoroadenine acyl CF3 S 6-N-acetyl-2-aminoadenine acyl CF3 S 6-N-acetyl-2-amino-8-fluoroadenine acyl CF3 S 2-N-acetylaminoadenine acyl CF3 S 2-N-acetylamino-8-fluoroadenine acyl CF3 S 2-N-acetylamino-8-fluorohypoxanthine acyl CF3 S 2-N-acetylaminohypoxanthine Table 6 R6 R R X Base R R CH3 O-acyl F O Thymine F H CH3 O-acyl F O Uracil F H CH3 0-acyl F 0 Guanine F H CH3 O-acyl F O Cytosine F H CH3 O-acyl F O Adenine F H CH3 O-acyl F O Hypoxanthine F H CH3 O-acyl F O 5-Fluorouracil F H CH3 O-ac 1 F O 8-Fluoro uanine F H CH3 O-acyl F O 5-Fluorocytosine F H CH3 O-acyl F O 8-Fluoroadenine F H CH3 O-ac 1 F O 2-Fluoroadenine F H CH3 O-acyl F O 2, 8-Difluoroadenine F H CH3 O-acyl F O 2-Fluorohypoxanthine F H CH3 O-acyl F O 8-Fluorohypoxanthine F H CH3 O-acyl F O 2, 8-Difluorohypoxanthine F H CH3 O-acyl F O 2-Aminoadenine F H CH3 O-ac 1 F O 2-Amino-8-fluoroadenine F H CH3 O-acyl F O 2-Amino-8-fluorohypoxanthine F H CH3 O-acyl F O 2-Aminohypoxanthine F H CH3 0-acyl F 0 2-N-acetyl guanine F H CH3 O-acyl F O 4-N-acetylcytosine F H CH3 O-acyl F O 6-N-acetyladenine F H CH3 O-acyl F O 2-N-acetyl-8-fluoroguanine F H CH3 0-acyl F 0 4-N-acetyl--fluorocytosine F H CH3 O-acyl F O 6-N-acetyl-2-fluoroadenine F H CH3 O-acyl F O 6-N-acetyl-2, 8-difluoroadenine F H CH3 0-acyl F 0 6-N-acetyl-2-aminoadenine F H CH3 O-acyl F O 6-N-acetyl-2-amino-8-fluoroadenine F H CH3 0-acyl F 0 2-N-acetylaminoadenine F H CH3 O-acyl F O 2-N-acetylamino-8-fluoroadenine F H CH3 O-acyl F O 2-N-acetylamino-8-fluorohypoxanthine F H CH3 O-acyl F O 2-N-acetylaminohypoxanthine F H CH3 O-acyl F O Thymine F O-amino acid CH3 O-acyl F O Uracil F O-amino acid CH3 O-acyl F O Guanine F O-amino acid CH3 O-acyl F O Cytosine F O-amino acid CH3 O-acyl F O Adenine F O-amino acid CH3 O-acyl F O Hypoxanthine F O-amino acid CH3 O-acyl F O 5-Fluorouracil F O-amino acid CH3 O-acyl F O 8-Fluoroguanine F O-amino acid CH3 O-acyl F O 5-Fluorocytosine F 0-amino acid CH3 O-acyl F O 8-Fluoroadenine F O-amino acid CH3 0-acyl F 0 2-Fluoroadenine F-mino acid CH3 O-acyl F O 2, 8-Difluoroadenine F O-amino acid CH3 O-acyl F O 2-Fluorohypoxanthine F 0-amino acid R"R R X Base Rl° R9 CH3 O-acyl F O 8-Fluorohypoxanthine F O-amino acid CH3 O-acyl F O 2, 8-Difluorohypoxanthine F O-amino acid CH3 O-acyl F O 2-Aminoadenine F O-amino acid CH3 O-acyl F O 2-Amino-8-fluoroadenine F O-amino acid CH3 O-acyl F O 2-Amino-8-fluorohypoxanthine F O-amino acid CH3 0-acyl F 0 2-Aminohypoxanthine F 0-amino acid CH3 O-acyl F O 2-N-acetylguanine F O-amino acid CH3 O-acyl F O 4-N-acetylcytosine F O-amino acid CH3 0-acyl F 0 6-N-acetyladenine F 0-amino acid CH3 O-acyl F O 2-N-acetyl-8-fluoroguanine F O-amino acid CH3 O-acyl F O 4-N-acetyl-5-fluorocytosine F O-amino acid CH3 O-acyl F O 6-N-acetyl-2-fluoroadenine F O-amino acid CH3 O-acyl F O 6-N-acetyl-2, 8-difluoroadenine F O-amino acid CH3 O-acyl F O 6-N-acetyl-2-aminoadenine F O-amino acid CH3 O-acyl F O 6-N-acetyl-2-amino-8-fluoroadenine F O-amino acid CH3 O-acyl F O 2-N-acetylaminoadenine F O-amino acid CH3 O-acyl F O 2-N-acetylamino-8-fluoroadenine F O-amino acid CH3 O-acyl F O 2-N-acetylamino-8-fluorohypoxanthine F O-amino acid CH3 O-acyl F O 2-N-acetylaminohypoxanthine F 0-amino acid CH3 O-acyl F O Thymine F O-acyl CH3 O-acyl F O Uracil F O-acyl CH3 O-acyl F O Guanine F O-acyl CH3 O-acyl F O Cytosine F O-acyl CH3 0-acyl F 0 Adenine F 0-acyl CH3 O-acyl F O Hypoxanthine F O-acyl CH3 O-acyl F O 5-Fluorouracil F O-acyl CH3 O-acyl F O 8-Fluoroguanine F O-acyl CH3 O-acyl F O 5-Fluorocytosine F O-acyl CH3 O-acyl F O 8-Fluoroadenine F O-acyl CH3 O-acyl F O 2-Fluoroadenine F O-acyl CH3 O-acyl F O 2, 8-Difluoroadenine F 0-acyl CH3 O-acyl F O 2-Fluorohypoxanthine F O-acyl CH3 O-acyl F O 8-Fluorohypoxanthine F O-acyl CH3 O-acyl F O 2, 8-Difluorohypoxanthine F O-acyl CH3 O-acyl F O 2-Aminoadenine F O-acyl CH3 O-acyl F O 2-Amino-8-fluoroadenine F O-acyl CH3 O-acyl F O 2-Amino-8-fluorohypoxanthine F O-acyl CH3 O-acyl F O 2-Aminohy oxanthine F O-ac 1 CH3 O-acyl F O 2-N-acetylguanine F O-acyl CH3 0-acyl F O 4-N-acetylcytosine F O-acyl CH3 O-acyl F O 6-N-acetyladenine F O-acyl CH3 0-acyl F 0 2-N-acetyl-8-fluoroguanine F 0-acyl CH3 O-acyl F O 4-N-acetyl-5-fluorocytosine F O-acyl CH3 O-acyl F O 6-N-acetyl-2-fluoroadenine F O-acyl CH3 O-acyl F O 6-N-acetyl-2, 8-difluoroadenine F O-acyl CH3 O-acyl F O 6-N-acetyl-2-aminoadenine F O-acyl CH3 O-acyl F O 6-N-acetyl-2-amino-8-fluoroadenine F O-acyl R R'R X Base R R CH3 O-acyl F O 2-N-acetylam inoadenine F O-acyI CH3 O-acyl F O 2-N-acetylamino-8-fluoroadenine F O-acyl CH3 O-acyl F O 2-N-acetylamino-8-fluorohypoxanthine F O-acyl CH3 O-acyl F O 2-N-acetylaminohypoxanthine F O-acyl CH3 O-acyl F O Thymine F OH CH3 O-acyl F O Uracil F OH CH3 0-acyl F 0 Guanine F OH CH3 O-acyl 1 0 Cytosine F OH CH3 O-acyl F O Adenine F OH CH3 O-acyl F O Hypoxanthine F OH CH3 O-acyl F O 5-Fluorouracil F OH CH3 O-acyl F O 8-Fluoroguanine F OH CH3 O-acyl F O 5-Fluorocytosine F OH CH3 O-acyl F O 8-Fluoroadenine F OH CH3 O-acyl F O 2-Fluoroadenine F OH CH3 O-acyl F O 2, 8-Difluoroadenine F OH CH3 O-acyl F O 2-Fluorohypoxanthine F OH CH3 O-acyl F O 8-Fluorohypoxanthine F OH CH3 O-acyl F O 2, 8-Difluorohypoxanthine F OH CH3 O-acyl F O 2-Aminoadenine F OH CH3 O-acyl F O 2-Amino-8-fluoroadenine F OH CH3 O-ac 1 F O 2-Amino-8-fluorohy oxanthine F OH CH3 O-acyl F O 2-Aminohypoxanthine F OH CH3 0-acyl F 0 2-N-acetylguanine F OH CH3 O-ac 1 F O 4-N-acetylcytosine F OH CH3 O-acyl F O 6-N-acetyladenine F OH CH3 O-acyl F O 2-N-acetyl-8-fluoroguanine F OH CH3 O-acyl F O 4-N-acetyl-5-fluorocytosine F OH CH3 O-acyl F O 6-N-acetyl-2-fluoroadenine F OH CH3 O-ac 1 F O 6-N-acetyl-2, 8-difluoroadenine F OH CH3 O-ac 1 F O 6-N-acet 1-2-aminoadenine F OH CH3 O-acyl F O 6-N-acetyl-2-amino-8-fluoroadenine F OH CH3 O-acyl F O 2-N-acetylaminoadenine F OH CH3 O-acyl F O 2-N-acetylamino-8-fluoroadenine F OH CH3 O-acyl F O 2-N-acetylamino-8-fluorohypoxanthine F OH CH3 O-acyl F O 2-N-acetylaminohypoxanthine F OH CH3 O-acyl F O Thymine Br H CH3 O-acyl F O Uracil Br H CH3 O-acyl F O Guanine Br H CH3 O-acyl I 0 Cytosine Br H CH3 O-acyl F O Adenine Br H CH3 O-acyl F 0 Hypoxanthine Br H CH3 O-acyl F O 5-Fluorouracil Br H CH3 O-acyl F O 8-Fluoroguanine Br H CH3 O-acyl F O 5-Fluorocytosine Br H CH3 O-acyl F O 8-Fluoroadenine Br H R6 R 7 R8 X Base Rl° R9 CH3 O-acyl F O 2-Fluoroadenine Br H CH3 O-acyl F O 2, 8-Difluoroadenine Br H CH3 O-acyl F O 2-Fluorohypoxanthine Br H CH3 O-acyl F O 8-Fluorohypoxanthine Br H CH3 O-acyl F O 2, 8-Difluorohypoxanthine Br H CH3 O-acyl F O 2-Aminoadenine Br H CH3 O-acyl F O 2-Amino-8-fluoroadenine Br H CH3 O-acyl F O 2-Amino-8-fluorohypoxanthine Br H CH3 O-acyl F O 2-Aminohypoxanthine Br H CH3 O-acyl F O 2-N-acetylguanine Br H CH3 O-acyl F O 4-N-acetylcytosine Br H CH3 O-acyl F O 6-N-acetyladenine Br H CH3 O-acyl F O 2-N-acetyl-8-fluoroguanine Br H CH3 O-acyl F O 4-N-acetyl-5-fluorocytosine Br H CH3 O-acyl F O 6-N-acetyl-2-fluoroadenine Br H CH3 O-acyl F O 6-N-acetyl-2, 8-difluoroadenine Br H CH3 O-acyl F O 6-N-acetyl-2-aminoadenine Br H CH3 O-acyl F O 6-N-acetyl-2-amino-8-fluoroadenine Br H CH3 0-acyl F 0 2-N-acetylaminoadenine Br H CH3 O-acyl F O 2-N-acetylamino-8-fluoroadenine Br H CH3 O-ac 1 F O 2-N-acetylamino-8-fluorohypoxanthine Br H CH3 O-acyl F O 2-N-acetylaminohypoxanthine Br H CH3 O-acyl F O Thymine Br O-amino acid CH3 O-acyl F O Uracil Br 0-amino acid CH3 O-acyl F O Guanine Br O-amino acid CH3 O-acyl F O Cytosine Br O-amino acid CH3 O-acyl F O Adenine Br O-amino acid CH3 O-acyl F O Hypoxanthine Br O-amino acid CH3 O-ac l F O 5-Fluorouracil Br 0-amino acid CH3 O-acyl F O 8-Fluoroguanine Br O-amino acid CH3 O-acyl F O 5-Fluorocytosine Br O-amino acid CH3 O-acyl F O 8-Fluoroadenine Br O-amino acid CH3 O-acyl F O 2-Fluoroadenine Br O-amino acid CH3 O-acyl F O 2, 8-Difluoroadenine Br O-amino acid CH3 O-acyl F O 2-Fluorohypoxanthine Br O-amino acid CH3 O-acyl F O 8-Fluorohypoxanthine Br O-amino acid CH3 O-acyl F O 2, 8-Difluoroh oxanthine Br O-amino acid CH3 O-acyl F O 2-Aminoadenine Br O-amino acid CH3 O-acyl F O 2-Amino-8-fluoroadenine Br O-amino acid CH3 O-acyl F O 2-Amino-8-fluorohypoxanthine Br O-amino acid CH3 O-acyl F O 2-Aminohypoxanthine Br 0-amino acid CH3 O-acyl F O 2-N-acetylguanine Br O-amino acid CH3 O-acyl F O 4-N-acetylcytosine Br O-amino acid CH3 O-acyl F O 6-N-acetyladenine Br O-amino acid CH3 O-acyl F O 2-N-acetyl-8-fluoroguanine Br O-amino acid CH3 O-acyl F O 4-N-acetyl-5-fluorocytosine Br O-amino acid CH3 O-acyl F O 6-N-acetyl-2-fluoroadenine Br O-amino acid R R R X Base Rio R9 CH3 O-ac 1 F O 6-N-acet 1-2, 8-difluoroadenine Br O-amino acid CH3 O-acyl F O 6-N-acetyl-2-aminoadenine Br O-amino acid CH3 O-acyl F O 6-N-acetyl-2-amino-8-fluoroadenine Br O-amino acid CH3 O-acyl F O 2-N-acetylaminoadenine Br O-amino acid CH3 O-acyl F O 2-N-acetylamino-8-fluoroadenine Br O-amino acid CH3 O-acyl F O 2-N-acetylamino-8-fluorohypoxanthine Br O-amino acid CH3 O-acyl F O 2-N-acetylaminohypoxanthine Br O-amino acid CH3 O-acyl F O Thymine Br O-acyl CH3 O-acyl F O Uracil Br O-acyl CH3 O-acyl F O Guanine Br O-acyl CH3 O-acyl 1 0 Cytosine Br O-acyl CH3 O-acyl F O Adenine Br O-acyl CH3 O-acyl F O Hypoxanthine Br O-acyl CH3 O-acyl F O 5-Fluorouracil Br O-acyl CH3 O-acyl F O 8-Fluoroguanine Br O-acyl CH3 O-acyl F O 5-Fluorocytosine Br O-acyl CH3 O-acyl F O 8-Fluoroadenine Br O-acyl CH3 O-acyl F O 2-Fluoroadenine Br O-acyl CH3 O-acyl F O 2, 8-Difluoroadenine Br O-acyl CH3 O-acyl F O 2-Fluorohypoxanthine Br O-acyl CH3 O-acyl F O 8-Fluorohypoxanthine Br O-acyl CH3 O-acyl F O 2, 8-Difluorohypoxanthine Br O-acyl CH3 O-acyl F O 2-Aminoadenine Br O-acyl CH3 O-acyl F O 2-Amino-8-fluoroadenine Br O-acyl CH3 O-ac 1 F O 2-Amino-8-fluorohy oxanthine Br O-acyl CH3 O-acyl F O 2-Aminohypoxanthine Br O-acyl CH3 O-ac I F O 2-N-acet 1 uanine Br O-acyl CH3 O-ac I F O 4-N-acetylc osine Br O-ac 1 CH3 O-ac 1 F O 6-N-acet ladenine Br O-ac 1 CH3 O-acyl F O 2-N-acetyl-8-fluoroguanine Br O-acyl CH3 0-acyl F 0 4-N-acetyl-5-fluorocytosine Br 0-acyl CH3 O-ac 1 F O 6-N-acet 1-2-fluoroadenine Br O-ac 1 CH3 O-acyl F O 6-N-acet 1-2, 8-difluoroadenine Br O-ac 1 CH3 O-acyl F O 6-N-acetyl-2-aminoadenine Br O-acyl CH3 O-ac 1 F O 6-N-acetyl-2-amino-8-fluoroadenine Br O-acyl CH3 O-acyl F O 2-N-acetylaminoadenine Br O-acyl CH3 O-acyl F O 2-N-acetylamino-8-fluoroadenine Br O-acyl CH3 O-acyl F O 2-N-acetylamino-8-fluorohypoxanthine Br O-acyl CH3 O-acyl F O 2-N-acetylaminohypoxanthine Br O-acyl CH3 O-acyl F O Thymine Br OH CH3 O-acyl F O Uracil Br OH CH3 O-acyl F O Guanine Br OH CH3 O-acyl F O Cytosine Br OH CH3 O-acyl F O Adenine Br OH CH3 O-acyl 1 0 Hypoxanthine Br OH CH3 O-acyl F O 5-Fluorouracil Br OH CH3 O-acyl F O 8-Fluoroguanine Br OH R6 R7 T X Base R R CH3 0-acyl F 0 5-Fluorocytosine Br OH CH3 O-acyl F O 8-Fluoroadenine Br OH CH3 O-acyl F O 2-Fluoroadenine Br OH CH3 O-acyl F O 2, 8-Difluoroadenine Br OH CH3 O-ac 1 F O 2-Fluoroh oxanthine Br OH CH3 O-ac 1 F O 8-Fluorohy oxanthine Br OH CH3 O-acyl F O 2, 8-Difluorohypoxanthine Br OH CH3 O-acyl F O 2-Aminoadenine Br OH CH3 O-acyl F O 2-Amino-8-fluoroadenine Br OH CH3 O-acyl F O 2-Amino-8-fluorohypoxanthine Br OH CH3 O-acyl F 0-Aminohypoxanthine Br OH CH3 O-acyl F O 2-N-acetyIguanine Br OH CH3 O-ac 1 F O 4-N-acetylcytosine Br OH CH3 O-acyl F O 6-N-acetyladenine Br OH CH3 0-acyl F 0 2-N-acetyl-8-fluoroguanine Br OH CH3 O-acyl F O 4-N-acetyl-5-fluorocytosine Br OH CH3 O-acyl F O 6-N-acetyl-2-fluoroadenine Br OH CH3 O-acyl F O 6-N-acetyl-2, 8-difluoroadenine Br OH CH3 O-acyl F O 6-N-acetyl-2-aminoadenine Br OH CH3 O-acyl F O 6-N-acetyl-2-amino-8-fluoroadenine Br OH CH3 O-acyl F O 2-N-acetylaminoadenine Br OH CH3 O-acyl F O 2-N-acetylamino-8-fluoroadenine Br OH CH3 O-acyl F O 2-N-acetylamino-8-fluorohypoxanthine Br OH CH3 O-acyl F O 2-N-acetylaminohypoxanthine Br OH CH3 O-acyl F O Thymine Cl O-acyl CH3 O-acyl F 0 Uracil Cl 0-acyl CH3 O-acyl F O Guanine Cl O-acyl CH3 O-acyl 1 O Cytosine Cl O-a CH3 0-acyl F O Adenine CI O-acyl CH3 O-acyl F O Hypoxanthine Cl 0-acyl CH3 O-acyl F O 5-Fluorouracil scI O-acyl CH3 O-acyl F O 8-Fluoroguanine Cl O-acyl CH3 O-acyl F O 5-Fluorocytosine Cl O-acyl CH3 O-acyl F O 8-Fluoroadenine Cl O-acyl CH3 O-acyl F O 2-Fluoroadenine Cl O-acyl CH3 O-acyl F O 2, 8-Difluoroadenine Cl O-acyl CH3 O-acyl F O 2-Fluorohypoxanthine Cl O-acyl CH3 O-acyl F O 8-Fluorohypoxanthine Cl O-acyl CH3 O-acyl F O 2, 8-Difluorohypoxanthine Cl 0-acyl CH3 O-acyl F O 2-Aminoadenine Cl O-acyl CH3 O-acyl F JE0 2-Amino-8-fluoroadenine Cl O-acyl CH3 O-acyl F Q 2-Amino-8-fluorohypoxanthine Cl O-acyl CH3 O-ac 1 F O 2-Aminohy oxanthine C1 O-acyl CH3 O-acyl F 0 2-N-acetylguanine Cl O-acyl CH3 O-ac 1 F O 4-N-acet lc osine C1 O-acyl CH3 O-ac 1 F O 6-N-acet ladenine CI O-ac 1 CH3 O-acyl F O 2-N-acetyl-8-fluoroguanine Cl O-acyl R R R X Base R R CH3 O-ac 1 F O 4-N-acetyl-5-fluorocytosine Cl O-acyl CH3 O-acyl F 0 6-N-acetyl-2-fluoroadenine Cl O-acyl CH3 O-acyl F O 6-N-acetyl-2, 8-difluoroadenine Cl O-ac 1 CH3 0-acyl F 0 6-N-acetyl-2-aminoadenine Cl 0-acyl CH3 O-acyl F Q 6-N-acetyl-2-amino-8-fluoroadenine Cl O-acyl CH3 O-ac 1 F O 2-N-acetylaminoadenine Cl O-ac 1 CH3 O-acyl F 0 2-N-acetylamino-8-fluoroadenine Cl O-acyl CH3 O-acyl F O 2-N-acetylamino-8-fluorohypoxanthine Cl O-acyl CH3 O-ac 1 F O 2-N-acetylaminoh oxanthine Cl O-ac 1 CH3 O-acyl F O Thymine Cl OH CH3 O-acyl F 0 Uracil Cl OH CH3 O-acyl F 0 Guanine Cl OH CH3 O-acyl F 0 Cytosine Cl OH CH3 O-acyl F O Adenine Cl OH CH3 O-acyl F O Hypoxanthine Cl OH CH3 O-acyl F O 5-Fluorouracil Cl OH CH3 O-acyl F Q 8-Fluoroguanine Cl OH CH3 O-ac 1 F O 5-Fluorocytosine C1 OH CH3 O-acyl F O 8-Fluoroadenine Cl OH CH3 O-acyl F O 2-Fluoroadenine Cl OH CH3 O-acyl F Q 2, 8-Difluoroadenine Cl OH CH3 O-acyl F 0 2-Fluorohypoxanthine Cl OH CH3 O-acyl F O 8-Fluorohypoxanthine Cl OH CH3 O-acyl F O 2, 8-Difluorohypoxanthine Cl OH CH3 O-acyl F O 2-Aminoadenine Cl OH CH3 O-acyl F Q 2-Amino-8-fluoroadenine Cl OH CH3 O-acyl F Q 2-Amino-8-fluorohypoxanthine Cl OH CH3 O-acyl F O 2-Aminohypoxanthine Cl OH CH3 O-acyl F O 2-N-acetylguanine Cl OH CH3 O-acyl F O 4-N-acetylcytosine C I OH CH3 O-acyl F O 6-N-acetyladenine Cl OH CH3 O-ac 1 F O 2-N-acet 1-8-fluoroguanine C1 OH CH3 O-ac 1 F O 4-N-acet 1-5-fluoroc osine Cl OH CH3 O-acyl F O 6-N-acetyl-2-fluoroadenine Cl OH CH3 0-acyl F 0 6-N-acetyl-2, 8-difluoroadenine Cl OH CH3 O-acyl F O 6-N-acetyl-2-aminoadenine Cl OH CH3 0-acyl F 0 6-N-acetyl-2-amino-8-fluoroadenine Cl OH CH3 O-acyl F O 2-N-acetylaminoadenine Cl OH CH3 O-acyl F O 2-N-acetylamino-8-fluoroadenine Cl OH CH3 O-acyl F O 2-N-acetylamino-8-fluorohypoxanthine Cl OH CH3 O-acyl F O 2-N-acetylaminohy oxanthine Cl OH CH3 O-acyl F O Thymine Cl H CH3 O-acyl F O Uracil Cl H CH3 O-acyl F O Guanine Cl H CH3 O-acyl 1 0 Cytosine Cl H CH3 O-acyl F O Adenine Cl H CH3 O-acyl F O Hypoxanthine Cl H F R7 F X Base R R CH3 O-acyl F O 5-Fluorouracil Cl H CH3 O-acyl F O 8-Fluoroguanine Cl H CH3 O-acyl F O 5-Fluorocytosine Cl H CH3 O-acyl F O 8-Fluoroadenine Cl H CH3 O-acyl F O 2-Fluoroadenine Cl H CH3 0-acyl F 0 2, 8-Difluoroadenine Cl H CH3 O-acyl F O 2-Fluorohypoxanthine Cl H CH3 O-acyl F O 8-Fluorohypoxanthine Cl H CH3 O-acyl F O 2, 8-Difluorohypoxanthine Cl H CH3 O-acyl F O 2-Aminoadenine Cl H CH3 O-ac 1 F O 2-Amino-8-fluoroadenine CI H CH3 O-acyl F O 2-Amino-8-fluoroh oxanthine C1 H CH3 O-acyl F O 2-Aminohypoxanthine Cl H CH3 O-acyl F O 2-N-acetyl guanine Cl H CH3 O-acyl F O 4-N-acetylcytosine Cl H CH3 O-acyl F O 6-N-acetyladenine Cl H CH3 O-acyl F O 2-N-acetyl-8-fluoroguanine Cl H CH3 O-acyl F O 4-N-acetyl-5-fluorocytosine Cl H CH3 O-acyl F 0 6-N-acetyl-2-fluoroadenine Cl H CH3 O-acyl F O 6-N-acetyl-2, 8-difluoroadenine Cl H CH3 O-acyl F O 6-N-acetyl-2-aminoadenine Cl H CH3 O-acyl F O 6-N-acetyl-2-amino-8-fluoroadenine Cl H CH3 O-acyl F O 2-N-acetylaminoadenine Cl H CH3 O-acyl F O 2-N-acetylamino-8-fluoroadenine Cl H CH3 O-acyl F O 2-N-acetylamino-8-fluorohypoxanthine Cl H CH3 O-acyl F O 2-N-acetylaminoh oxanthine Cl H CH3 O-acyl F O Thymine Cl O-amino acid CH3 O-acyl F O Uracil Cl O-amino acid CH3 O-acyl F O Guanine Cl O-amino acid CH3 O-acyl F O C osine Cl O-amino acid CH3 O-acyl F O Adenine Cl O-amino acid CH3 O-acyl F O Hypoxanthine Cl O-amino acid CH3 O-acyl F O 5-Fluorouracil Cl O-amino acid CH3 O-acyl F O 8-Fluoroguanine Cl O-amino acid CH3 O-acyl F O 5-Fluorocytosine Cl O-amino acid CH3 O-acyl F O 8-Fluoroadenine Cl O-amino acid CH3 O-acyl F O 2-Fluoroadenine Cl O-amino acid CH3 O-acyl F O 2, 8-Difluoroadenine CI O-amino acid CH3 O-acyl F O 2-Fluorohypoxanthine Cl O-amino acid CH3 O-acyl F O 8-Fluoroh oxanthine Cl O-amino acid CH3 O-acyl F O 2, 8-Difluorohypoxanthine Cl O-amino acid CH3 0-acyl F 0 2-Aminoadenine Cl 0-amino acid CH3 O-acyl F O 2-Amino-8-fluoroadenine Cl O-amino acid CH3 O-acyl F 0 2-Amino-8-fluorohypoxanthine CI O-amino acid CH3 O-acyl F O 2-Aminohy oxanthine C1 O-amino acid CH3 O-ac I F O 2-N-acet lguanine Cl O-amino acid CH3 O-acyl F Q 4-N-acetylcytosine Cl O-amino acid R R R X Base R R CH3 O-acyl F O 6-N-acetyladenine Cl O-amino acid CH3 O-acyl F O 2-N-acetyl-8-fluoroguanine Cl O-amino acid CH3 O-acyl F O 4-N-acet 1-5-fluorocytosine Cl O-amino acid CH3 O-ac 1 F O 6-N-ace 1-2-fluoroadenine CI O-amino acid CH3 O-acyl F Q 6-N-acetyl-2, 8-difluoroadenine Cl O-amino acid CH3 O-acyl F O 6-N-acetyl-2-aminoadenine Cl O-amino acid CH3 O-acyl F O 6-N-acetyl-2-amino-8-fluoroadenine Cl O-amino acid CH3 O-acyl F O 2-N-acetylaminoadenine Cl O-amino acid CH3 O-ac 1 F O 2-N-acetylamino-8-fluoroadenine Cl O-amino acid CH3 O-acyl F O 2-N-acetylamino-8-fluorohypoxanthine Cl O-amino acid CH3 O-acyl F O 2-N-acetylaminohypoxanthine Cl O-amino acid CH3 O-acyl F O Thymine H H CH3 O-acyl F O Uracil H H CH3 O-acyl F O Guanine H H CH3 0-acyl F 0 Cytosine H H CH3 O-acyl F O Adenine H H CH3 O-acyl F O Hypoxanthine H H CH3 O-acyl F O 5-Fluorouracil H H CH3 O-acyl F O 8-Fluoroguanine H H CH3 0-acy) JF0 5-F) uorocytosineJHH CH3 O-acyl F O 8-Fluoroadenine H H CH3 O-acyl F 0 2-Fluoroadenine H H CH3 O-acyl F Q 2, 8-Difluoroadenine H H CH3 O-acyl F 0 2-Fluorohypoxanthine H H CH3 O-ac 1 F O 8-Fluorohy oxanthine H H CH3 O-ac 1 F O 2, 8-Difluorohypoxanthine H H CH3 O-acyl F 0 2-Aminoadenine H H CH3 O-acyl F O 2-Amino-8-fluoroadenine H H CH3 O-acyl F O 2-Amino-8-fluorohypoxanthine H H CH3 O-acyl F O 2-Aminohypoxanthine H H CH3 O-acyl F O 2-N-acetylguanine H H CH3 O-acyl F O 4-N-acetylcytosine H H CH3 O-acyl F O 6-N-acetyladenine H H CH3 O-acyl F O 2-N-acetyl-8-fluoroguanine H H CH3 O-acyl F O 4-N-aceteI-5-fluorocytosine H H CH3 O-acyl F O 6-N-acetyl-2-fluoroadenine H H CH3 O-acyl F O 6-N-acetyl-2, 8-difluoroadenine H H CH3 O-acyl F Q 6-N-acetyl-2-aminoadenine H H CH3 O-acyl F O 6-N-acetyl-2-amino-8-fluoroadenine H H CH3 O-acyl F 0 2-N-acetylaminoadenine H H CH3 O-acyl F O 2-N-acetylamino-8-fluoroadenine H H CH3 O-acyl F O 2-N-acetylamino-8-fluorohypoxanthine H H CH3 O-acyl F O 2-N-acetylaminohypoxanthine H H CH3 O-acyl F O Thymine H O-amino acid CH3 O-acyl F O Uracil H O-amino acid CH3 O-acyl F O Guanine H O-amino acid CH3 O-acyl F O Cytosine H O-amino acid R6 R'T X Base Rl° R9 CH3 O-acyl F O Adenine H O-amino acid CH3 O-acyl F O Hypoxanthine H O-amino acid CH3 O-acyl F O 5-Fluorouracil H O-amino acid CH3 O-acyl F O 8-Fluoroguanine H O-amino acid CH3 O-acyl F O 5-Fluorocytosine H O-amino acid CH3 O-acyl F O 8-Fluoroadenine H O-amino acid CH3 O-acyl F O 2-Fluoroadenine H O-amino acid CH3 0-acyl F 0 2, 8-Difluoroadenine H O-amino acid CH3 0-acyl F 0 2-Fluorohypoxanthine H 0-amino acid CH3 O-acyl F O 8-Fluorohypoxanthine H O-amino acid CH3 O-acyl F O 2, 8-Difluorohypoxanthine H 0-amino acid CH3 O-acyl F O 2-Aminoadenine H O-amino acid CH3 O-acyl F O 2-Amino-8-fluoroadenine H O-amino acid CH3 0-acyl F 0 2-Amino-8-fluorohypoxanthine H 0-amino acid CH3 O-acyl F O 2-Aminohypoxanthine H O-amino acid CH3 0-acyl F 0 2-N-acetylguanine H 0-amino acid CH3 O-acyl F O 4-N-acetylcytosine H O-amino acid CH3 O-acyl F O 6-N-acetyladenine H O-amino acid CH3 O-acyl F O 2-N-acetyl-8-fluoroguanine H O-amino acid CH3 O-acyl F O 4-N-acetyl-5-fluorocytosine H O-amino acid CH3 O-acyl F O 6-N-acetyl-2-fluoroadenine H O-amino acid CH3 O-acyl F O 6-N-acetyl-2, 8-difluoroadenine H O-amino acid CH3 O-acyl F O 6-N-acetyl-2-aminoadenine H O-amino acid CH3 O-acyl F O 6-N-acetyl-2-amino-8-fluoroadenine H O-amino acid CH3 0-acyl F 0 2-N-acetylaminoadenine H 0-amino acid CH3 O-acyl F O 2-N-acetylamino-8-fluoroadenine H O-amino acid CH3 O-acyl F O 2-N-acetylamino-8-fluorohypoxanthine H 0-amino acid CH3 O-acyl F O 2-N-acetylaminohypoxanthine H O-amino acid CH3 O-acyl F O Thymine H O-acyl CH3 O-acyl F O Uracil H O-acyl CH3 0-acyl F 0 Guanine H 0-acyl CH3 O-acyl F O Cytosine H O-acyl CH3 0-acyl F 0 Adenine H 0-acyl CH3 O-acyl F O Hypoxanthine H O-acyl CH3 O-acyl F O 5-Fluorouracil H O-acyl CH3 O-acyl F O 8-Fluoroguanine H O-acyl CH3 O-acyl F O 5-Fluorocytosine H O-acyl CH3 O-acyl F O 8-Fluoroadenine H O-acyl CH3 O-acyl F O 2-Fluoroadenine H O-acyl CH3 O-acyl F O 2, 8-Difluoroadenine H O-acyl CH3 O-acyl F O 2-Fluorohypoxanthine H O-acYI CH3 O-acyl F O 8-Fluorohypoxanthine H O-acyl CH3 O-acyl F O 2, 8-Difluorohypoxanthine H O-ac CH3 O-acyl F O 2-Aminoadenine H O-acyl CH3 O-acyl F O 2-Amino-8-fluoroadenine H O-acyl CH3 O-acyl F O 2-Amino-8-fluorohypoxanthine H O-acyl CH3 O-ac 1 F O 2-Aminoh oxanthine H O-ac I R6 R'T T Base Rl° R9 CH3 0-acy) F W 2-N-acetylguanine H O-acyl CH3 0-acyl F 0 4-N-acetylcytosine H 0-acyl CH3 O-acyl F O 6-N-acetyladenine H O-acyl CH3 O-acyl F O 2-N-acetyl-8-fluoroguanine H O-acyl CH3 O-acyl F O 4-N-acetyl-5-fluorocytosine H O-acyl CH3 O-acyl F O 6-N-acetyl-2-fluoroadenine H O-acyl CH3 0-acyl F 0 6-N-acetyl-2, 8-difluoroadenine H 0-acyl CH3 O-acyl F O 6-N-acetyl-2-aminoadenine H O-ac 1 CH3 0-acyl F 0 6-N-acetyl-2-amino-8-fluoroadenine H 0-acyl CH3 O-ac 1 F O 2-N-acetylaminoadenine H O-acyl CH3 O-acyl F O 2-N-acetylamino-8-fluoroadenine H O-acyl CH3 O-acyl F O 2-N-acetylamino-8-fluorohypoxanthine H O-acyl CH3 O-acyl F O 2-N-acetylaminohypoxanthine H O-acyl CH3 O-acyl F O Thymine H OH CH3 O-acyl F O Uracil H OH CH3 O-acyl F O Guanine H OH CH3 O-acyl F O Cytosine H OH CH3 O-acyl F O Adenine H OH CH3 O-acyl F O Hypoxanthine H OH CH3 O-acyl F O 5-Fluorouracil H OH CH3 O-acyl F O 8-Fluoroguanine H OH CH3 O-acyl F O 5-Fluorocytosine H OH CH3 O-acyl F O 8-Fluoroadenine H OH CH3 O-acyl F O 2-Fluoroadenine H OH CH3 O-acyl F O 2, 8-Difluoroadenine H OH CH3 O-acyl F O 2-Fluorohypoxanthine H OH CH3 0-acyl F 0 8-Fluorohypoxanthine H OH CH3 O-acyl F O 2, 8-Difluorohypoxanthine H OH CH3 O-acyl F O 2-Aminoadenine H OH CH3 0-acyl F 0 2-Amino-8-fluoroadenine H OH CH3 O-acyl F O 2-Amino-8-fluorohypoxanthine H OH CH3 O-acyl F O 2-Aminohypoxanthine H OH CH3 O-acyl F O 2-N-acetylguanine H OH CH3 O-acyl F O 4-N-acetylcytosine H OH CH3 O-acyl F O 6-N-acetyladenine H OH CH3 O-acyl F O 2-N-acetyl-8-fluoroguanine H OH CH3 O-acyl F O 4-N-acetyl-5-fluorocytosine H OH CH3 O-acyl F O 6-N-acetyl-2-fluoroadenine H OH CH3 O-acyl F O 6-N-acetyl-2, 8-difluoroadenine H OH CH3 O-acyl F O 6-N-acetyl-2-aminoadenine H OH CH3 0-acyl F 0 6-N-acetyl-2-amino-8-fluoroadenine H OH CH3 O-acyl F O 2-N-acetylaminoadenine H OH CH3 O-acyl F O 2-N-acetylamino-8-fluoroadenine H OH CH3 O-acyl F O 2-N-acetylamino-8-fluorohypoxanthine H OH CH3 O-acyl F O 2-N-acetylaminohypoxanthine H OH CH3 O-acyl F O Thymine OH H CH3 O-acyl F O Uracil OH H R6 R'T X Base Rl° R9 CH3 O-acyl F O Guanine OH H CH3 O-acyl F 0 Cytosine OH H CH3 O-acyl F O Adenine OH H CH3 O-acyl F 0 Hypoxanthine OH H CH3 O-ac 1 F O 5-Fluorouracil OH H CH3 O-acyl F O 8-Fluoro uanine OH H CH3 O-ac 1 F O 5-Fluoroc osine OH H CH3 O-acyl F O 8-Fluoroadenine OH CH3 O-acyl F O 2-Fluoroadenine OH H CH3 O-acyl F O 2, 8-Difluoroadenine OH H CH3 O-acyl F 0 2-Fluorohypoxanthine OH H CH3 O-acyl F O 8-Fluorohypoxanthine OH H CH3 O-acyl F O 2, 8-Difluorohypoxanthine OH H CH3 O-acyl F O 2-Aminoadenine OH H CH3 O-acyl F O 2-Amino-8-fluoroadenine OH H CH3 O-acyl F O 2-Amino-8-fluorohypoxanthine OH H CH3 O-acyl F O 2-Aminohypoxanthine OH H CH3 O-acyl F O 2-N-acetylguanine OH H CH3 O-acyl F O 4-N-acetylcytosine OH H CH3 O-acyl F O 6-N-acetyladenine OH H CH3 O-acyl F O 2-N-acetyl-8-fluoroguanine OH H CH3 O-ac 1 F O 4-N-acetyl-5-fluoroc osine OH H CH3 O-acyl F O 6-N-acetyl-2-fluoroadenine OH H CH3 O-acyl F O 6-N-acetyl-2, 8-difluoroadenine OH H CH3 O-ac 1 F O 6-N-acet 1-2-aminoadenine OH H CH3 O-acyl F O 6-N-acetyl-2-amino-8-fluoroadenine OH H CH3 O-ac 1 F O 2-N-acet laminoadenine OH H CH3 O-acyl F O 2-N-acetylamino-8-fluoroadenine OH H CH3 O-ac 1 F O 2-N-acet lamino-8-fluorohy oxanthine OH H CH3 O-acyl F O 2-N-acetylaminohypoxanthine OH H CH3 O-acyl Br 0 Thymine F H CH3 0-acyl Br 0 Uracil F H CH3 0-acy) Br 0 Guanine F H CH3 O-acyl Br O Cytosine F H CH3 O-acyl Br O Adenine F H CH3 0-acyl Br 0 Hypoxanthine F H CH3 O-acyl Br O 5-Fluorouracil F H CH3 O-acyl Br O 8-Fluoroguanine F H CH3 O-acyl Br O 5-Fluorocytosine F H CH3 O-acyl Br O 8-Fluoroadenine F H CH3 O-acyl Br O 2-Fluoroadenine F H CH3 O-acyl Br O 2, 8-Difluoroadenine F H CH3 O-acyl Br 0 2-Fluorohypoxanthine F H CH3 O-acyl Br 0 8-Fluorohypoxanthine F H CH3 0-acryl Br O 2, 8-Difluorohypoxanthine F H CH3 0-acyl Br 0 2-Aminoadenine F H CH3 O-acyl Br O 2-Amino-8-fluoroadenine F H R R R X Base Rl° R9 CH3 0-acyl Br 0 2-Amino-8-fluorohypoxanthine F H CH3 O-acyl Br 0 2-Aminohypoxanthine F H CH3 O-acyl Br O 2-N-acetylguanine F H CH3 O-acyl Br O 4-N-acetylcytosine F H CH3 O-acyl Br O 6-N-acetyladenine F H CH3 O-acyl Br O 2-N-acetyl-8-fluoroguanine F H CH3 O-acyl Br O 4-N-acetyl-5-fluorocytosine F H CH3 O-acyl Br O 6-N-acetyl-2-fluoroadenine F H CH3 O-acyl Br O 6-N-acetyl-2, 8-difluoroadenine F H CH3 O-acyl Br O 6-N-acetyl-2-aminoadenine F H CH3 O-acyl Br O 6-N-acetyl-2-amino-8-fluoroadenine F H CH3 O-acyl Br O 2-N-acetylaminoadenine F H CH3 O-acyl Br O 2-N-acetylamino-8-fluoroadenine F H CH3 O-acyl Br O 2-N-acetylamino-8-fluorohypoxanthine F H CH3 O-acyl Br O 2-N-acetylaminohypoxanthine F H CH3 O-acyl Br O Thymine F O-amino acid CH3 O-acyl Br O Uracil F O-amino acid CH3 O-acyl Br O Guanine F O-amino acid CH3 O-acyl Br O Cytosine F O-amino acid CH3 O-acyl Br O Adenine F O-amino acid CH3 O-acyl Br O Hypoxanthine F 0-amino acid CH3 O-acyl Br O 5-Fluorouracil F O-amino acid CH3 O-acyl Br O 8-Fluoroguanine F O-amino acid CH3 O-acyl Br O 5-Fluorocytosine F O-amino acid CH3 O-acyl Br O 8-Fluoroadenine F O-amino acid CH3 O-acyl Br O 2-Fluoroadenine F O-amino acid CH3 O-acyl Br 0 2, 8-Difluoroadenine F O-amino acid CH3 O-acyl Br O 2-Fluorohypoxanthine F O-amino acid CH3 O-acyl Br O 8-Fluorohypoxanthine F O-amino acid CH3 O-acyl Br O 2, 8-Difluorohypoxanthine F O-amino acid CH3 O-acyl Br O 2-Aminoadenine F O-amino acid CH3 O-acyl Br 0 2-Amino-8-fluoroadenine F O-amino acid CH3 O-acyl Br 0 2-Amino-8-fluorohypoxanthine F O-amino acid CH3 O-acyl Br 0 2-Aminohypoxanthine F 0-amino acid CH3 O-acyl Br 0 2-N-acetylguanine F O-aminoacid CH3 O-acyl Br O 4-N-acetylcytosine F O-amino acid CH3 O-acyl Br O 6-N-acet ladenine F O-amino acid CH3 O-acyl Br O 2-N-acetyl-8-fluoroguanine F O-amino acid CH3 0-acyl Br 0 4-N-acetyl-5-fluorocytosine F 0-amino acid CH3 O-acyl Br O 6-N-acetyl-2-fluoroadenine F O-amino acid CH3 O-acyl Br O 6-N-acetyl-2, 8-difluoroadenine F O-amino acid CH3 O-acyl Br O 6-N-acetyl-2-aminoadenine F O-amino acid CH3 O-acyl Br O 6-N-acetyl-2-amino-8-fluoroadenine F O-amino acid CH3 O-acyl Br O 2-N-acetylaminoadenine F O-amino acid CH3 O-acyl Br O 2-N-acetylamino-8-fluoroadenine F O-amino acid CH3 O-acyl Br O 2-N-acet lamino-8-fluoroh oxanthine F O-amino acid CH3 O-acyl Br O 2-N-acetylaminohypoxanthine F 0-amino acid R R R X Base Rl°--R9 CH3 0-acyl Br 0 Thymine F O-acyl CH3 O-acyl Br 0 Uracil F O-acyl CH3 O-acyl Br O Guanine F 0-acyl CH3 0-acyl Br 0 Cytosine F 0-acyl CH3 0-acyl Br 0 Adenine F 0-acyl CH3 O-acyl Br 0 Hypoxanthine F O-acyl CH3 O-acyl Br 0 5-Fluorouracil F O-acyl CH3 O-acyl Br O 8-Fluoro uanine F O-ac 1 CH3 O-acyl Br 0 5-Fluorocytosine F O-acyl CH3 O-acyl Br 0 8-Fluoroadenine F O-acyl CH3 O-acyl Br 0 2-Fluoroadenine F O-acyl CH3 O-acyl Br 0 2, 8-Difluoroadenine F 0-acyl CH3 O-acyl Br O 2-Fluorohypoxanthine F O-acyl CH3 O-acyl Br O 8-Fluorohypoxanthine F O-acyl CH3 O-acyl Br O 2, 8-Difluorohy oxanthine F O-acyl CH3 O-acyl Br O 2-Aminoadenine F O-acyl CH3 O-acyl Br O 2-Amino-8-fluoroadenine F O-acyl CH3 O-acyl Br O 2-Amino-8-fluorohypoxanthine F O-acyl CH3 O-acyl Br O 2-Aminohypoxanthine F 0-acyl CH3 O-acyl Br O 2-N-acetylguanine F O-acyl CH3 O-acyl Br O 4-N-acetylcytosine F 0-acyl CH3 O-acyl Br O 6-N-acetyladenine F O-acyl CH3 O-acyl Br O 2-N-acetyl-8-fluoroguanine F O-acyl CH3 O-acyl Br O 4-N-acetyl-5-fluorocytosine F O-acyl CH3 O-acyl Br O 6-N-acetyl-2-fluoroadenine F O-acyl CH3 O-acyl Br O 6-N-acetyl-2, 8-difluoroadenine F O-acyl CH3 O-acyl Br O 6-N-acetyl-2-aminoadenine F O-ac 1 CH3 O-acyl Br O 6-N-aceteI-2-amino-8-fluoroadenine F O-acyl CH3 0-acy) Br O 2-N-acetylaminoadenine F 0-acyl CH3 0-acyl Br O 2-N-acetylamino-8-fluoroadenine F O-acyl CH3 O-acyl Br O 2-N-acetylamino-8-fluorohypoxanthine F O-acyl CH3 0-acy) Br O 2-N-acetylaminohypoxanthine F O-acyl CH3 0-acy) Br O Thymine F OH CH3 O-acyl Br O Uracil F OH CH3 O-acyl Br O Guanine F OH f CH3 O-acyl Br O Cytosine F OH CH3 O-acyl Br O Adenine F OH CH3 O-acyl Br O Hypoxanthine F OH CH3 O-acyl Br O 5-Fluorouracil F OH CH3 O-acyl Br O 8-Fluoroguanine F OH CH3 O-acyl Br O 5-Fluorocytosine F OH CH3 O-acyl Br O 8-Fluoroadenine F OH CH3 O-acyl Br O 2-Fluoroadenine F OH CH3 O-acyl Br O 2, 8-Difluoroadenine F OH CH3 O-acyl Br O 2-Fluorohypoxanthine F OH CH3 O-acyl Br O 8-Fluorohypoxanthine F OH CH3 O-acyl Br O 2, 8-Difluorohypoxanthine F OH R R R X Base R'° P CH3 O-acyl Br Q 2-Aminoadenine F OH CH3 O-acyl Br 0 2-Amino-8-fluoroadenine F OH CH3 O-acyl Br 0 2-Amino-8-fluorohypoxanthine F OH CH3 O-acyl Br 0 2-Aminohypoxanthine F OH CH3 O-acyl Br O 2-N-acetylguanine F OH CH3 O-acyl Br 0 4-N-acetylcytosine F OH CH3 O-acyl Br 0 6-N-acetyladenine F OH CH3 O-acyl Br O 2-N-acetyl-8-fluoroguanine F OH CH3 O-acyl Br O 4-N-acetyl-5-fluorocytosine F OH CH3 O-acyl Br O 6-N-acetyl-2-fluoroadenine F OH CH3 O-acyl Br 0 6-N-acetyl-2, 8-difluoroadenine F OH CH3 O-acyl Br O 6-N-acetyl-2-aminoadenine F OH CH3 O-acyl Br 0 6-N-acetyl-2-amino-8-fluoroadenine F OH CH3 O-acyl Br O 2-N-acetylaminoadenine F OH CH3 O-acyl Br O 2-N-acetylamino-8-fluoroadenine F OH CH3 0-acyl Br 0 2-N-acetylamino-8-fluorohypoxanthine F OH CH3 O-acyl Br O 2-N-acetylaminohypoxanthine F OH CH3 O-acyl Br O Thymine Br H CH3 O-acyl Br O Uracil Br H CH3 O-acyl Br O Guanine Br H CH3 O-acyl Br O Cytosine Br H CH3 O-acyl Br O Adenine Br H CH3 O-acyl Br O Hypoxanthine Br H CH3 O-acyl Br O 5-Fluorouracil Br H CH3 0-acy) Br O 8-Fluoroguanine Br H CH3 O-acyl Br O 5-Fluorocytosine Br H CH3 O-acyl Br O 8-Fluoroadenine Br H CH3 O-acyl Br O 2-Fluoroadenine Br H CH3 O-acyl Br O 2, 8-Difluoroadenine Br H CH3 O-acyl Br O 2-Fluorohypoxanthine Br H CH3 O-acyl Br O 8-Fluorohypoxanthine Br H CH3 0-acyl Br 0 2, 8-Difluorohypoxanthine Br H CH3 O-acyl Br O 2-Aminoadenine Br H CH3 O-acyl Br O 2-Amino-8-fluoroadenine Br H CH3 0-acyl Br 0 2-Amino-8-fluorohypoxanthine Br H CH3 O-acyl Br O 2-Aminohypoxanthine Br H CH3 O-acyl Br O 2-N-acetylguanine Br H CH3 0-acyl Br 0 4-N-acetylcytosine Br H CH3 0-acyl Br O 6-N-acetyladenine Br H CH3 O-acyl Br O 2-N-acetyl-8-fluoroguanine Br H CH3 O-acyl Br O 4-N-acetyl-5-fluorocytosine Br H CH3 O-acyl Br O 6-N-acetyl-2-fluoroadenine Br H CH3 O-acyl Br O 6-N-acetyl-8-difluoroadenine Br H CH3 O-acyl Br O 6-N-acetyl-2-aminoadenine Br H CH3 O-acyl Br O 6-N-acetyl-2-amino-8-fluoroadenine Br H CH3 O-acyl Br O 2-N-acetylaminoadenine Br H CH3 O-acyl Br O 2-N-acetylamino-8-fluoroadenine Br H R6 X Base Rl° R9 CH3 O-acyl Br O 2-N-acetylamino-8-fluorohypoxanthine Br H CH3 O-acyl Br O 2-N-acetylaminohypoxanthine Br H CH3 0-acyl Br 0 Thymine Br 0-amino acid CH3 O-acyl Br O Uracil Br O-amino acid CH3 O-acyl Br O Guanine Br O-amino acid CH3 O-acyl Br O Cytosine Br O-amino acid CH3 O-acyl Br O Adenine Br O-amino acid CH3 0-acyl Br O Hypoxanthine Br 0-amino acid CH3 O-acyl Br 5-Fluorouracil Br O-amino acid CH3 O-acyl Br O 8-Fluoroguanine Br O-amino acid CH3 O-acyl Br O S-Fluorocytosine Br O-amino acid CH3 O-acyl Br O 8-Fluoroadenine Br O-amino acid CH3 O-acyl Br O 2-Fluoroadenine Br O-amino acid CH3 O-acyl Br O 2, 8-Difluoroadenine Br O-amino acid CH3 O-acyl Br O 2-Fluorohypoxanthine Br O-amino acid CH3 O-acyl Br O 8-Fluorohypoxanthine Br O-amino acid CH3 O-acyl Br O 2, 8-Difluorohypoxanthine Br O-amino acid CH3 O-acyl Br O 2-Aminoadenine Br O-amino acid CH3 O-acyl Br O 2-Amino-8-fluoroadenine Br O-amino acid CH3 O-acyl Br O 2-Amino-8-fluorohypoxanthine Br O-amino acid CH3 O-acyl Br O 2-Aminohy oxanthine Br O-amino acid CH3 O-acyl Br O 2-N-acetylguanine Br O-amino acid CH3 O-acyl Br O 4-N-acetylcytosine Br O-amino acid CH3 O-acyl Br O 6-N-acetyladenine Br O-amino acid CH3 O-acyl Br O 2-N-acetyl-8-fluoroguanine Br O-amino acid CH3 O-acyl Br O 4-N-acetYI-5-fluorocytosine Br O-amino acid CH3 O-acyl Br O 6-N-acetyl-2-fluoroadenine Br O-amino acid CH3 O-acyl Br O 6-N-acetYI-2, 8-difluoroadenine Br O-amino acid CH3 O-acyl Br O 6-N-acetyl-2-aminoadenine Br O-amino acid CH3 O-acyl Br O 6-N-acetyl-2-amino-8-fluoroadenine Br O-amino acid CH3 O-acyl Br O 2-N-acetylaminoadenine Br 0-amino acid CH3 O-acyl Br 0 2-N-acetylamino-8-fluoroadenine Br O-amino acid CH3 O-acyl Br O 2-N-acetylamino-8-fluorohypoxanthine Br 0-amino acid CH3 O-acyl Br O 2-N-acetylaminohypoxanthine Br O-amino acid CH3 0-acryl Br O Thymine Br O-acyl CH3 O-acyl Br O Uracil Br O-acyl CH3 O-acyl Br O Guanine Br O-acyl CH3 O-acyl Br O Cytosine Br O-acyl CH3 O-acyl Br O Adenine Br O-acyl CH3 O-acyl Br O Hypoxanthine Br O-acyl CH3 O-acyl Br O 5-Fluorouracil Br O-acyl CH3 O-acyl Br O 8-Fluoroguanine Br O-acyl CH3 O-acyl Br O 5-Fluorocytosine Br O-acyl CH3 O-acyl Br O 8-Fluoroadenine Br O-acyl CH3 O-acyl Br O 2-Fluoroadenine Br O-acyl CH3 O-acyl Br O 2, 8-Difluoroadenine Br O-ac 1 CH3 O-acyl Br O 2-Fluorohypoxanthine Br O-acyl R R R X Base R R CH3 O-acyl Br O 8-Fluorohypoxanthine Br O-acyl CH3 O-acyl Br O 2, 8-Difluorohypoxanthine Br O-acyl CH3 O-acyl Br O 2-Aminoadenine Br O-acyl CH3 O-acyl Br O 2-Amino-8-fluoroadenine Br O-acyl CH3 O-acyl Br O 2-Amino-8-fluoroh oxanthine Br O-ac 1 CH3 O-ac 1 Br O 2-Aminoh oxanthine Br O-ac 1 CH3 O-acyl Br O 2-N-acetylguanine Br O-acyl CH3 O-acyl Br O 4-N-acetylcytosine Br O-acyl CH3 O-acyl Br O 6-N-acetyladenine Br O-acyl CH3 O-acyl Br O 2-N-acetyl-8-fluoroguanine Br O-acyl CH3 O-acyl Br O 4-N-acetyl-5-fluorocytosine Br O-acyl CH3 O-acyl Br O 6-N-acetyl-2-fluoroadenine Br O-acyl CH3 O-acyl Br O 6-N-acetyl-2, 8-difluoroadenine Br O-acyl CH3 O-acyl Br O 6-N-acetyl-2-aminoadenine Br O-acyl CH3 O-acyl Br O 6-N-acetyl-2-amino-8-fluoroadenine Br O-acyl CH3 O-acyl Br O 2-N-acetylaminoadenine Br O-acyl CH3 O-acyl Br O 2-N-acetylamino-8-fluoroadenine Br O-acyl CH3 O-acyl Br O 2-N-acetylamino-8-fluorohypoxanthine Br O-acyl CH3 O-acyl Br O 2-N-acetylaminohypoxanthine Br 0-acyl CH3 O-acyl Br O Thymine Br OH CH3 O-acyl Br O Uracil Br OH CH3 O-acyl Br O Guanine Br OH CH3 O-acyl Br O Cytosine Br OH CH3 O-acyl Br O Adenine Br OH CH3 O-acyl Br O Hypoxanthine Br OH CH3 O-acyl Br O 5-Fluorouracil Br OH CH3 O-acyl Br O 8-Fluoroguanine Br OH CH3 O-acyl Br O 5-Fluorocytosine Br OH CH3 O-acy1 Br O 8-Fluoroadenine Br OH CH3 O-acyl Br O 2-Fluoroadenine Br OH CH3 O-acyl Br O 2, 8-Difluoroadenine Br OH CH3 O-acyl Br O 2-Fluorohypoxanthine Br OH CH3 0-acryl Br O 8-Fluorohypoxanthine Br OH CH3 O-acyl Br O 2, 8-Difluorohypoxanthine Br OH CH3 O-acyl Br O 2-Aminoadenine Br OH CH3 O-acyl Br O 2-Amino-8-fluoroadenine Br OH CH3 O-acyl Br O 2-Amino-8-fluorohypoxanthine Br OH CH3 0 O-acyi Br O 2-Aminohypoxanthine Br OH CH3 O-acyl Br O 2-N-acetylguanine Br OH CH3 0-acy) Br O 4-N-acetylcytosine Br OH CH3 O-acyl Br O 6-N-acetyladenine Br OH CH3 O-acyl Br O 2-N-acetyl-8-fluoroguanine Br OH CH3 O-acyl Br O 4-N-acetyl-5-fluorocytosine Br OH CH3 O-acyl Br O 6-N-acetyl-2-fluoroadenine Br OH CH3 O-acyl Br O 6-N-acetyl-2, 8-difluoroadenine Br OH CH3 0-acy) Br O 6-N-acetyl-2-aminoadenine Br OH CH3 0-acyl 0 6-N-acetyl-2-amino-8-fluoroadenine Br OH R 6 R 7 R8 X Base Rl° R9 CH3 O-acyl Br O 2-N-acetylaminoadenine Br OH CH3 O-acyl Br O 2-N-acetylamino-8-fluoroadenine Br OH CH3 O-acyl Br O 2-N-acetylamino-8-fluorohypoxanthine Br OH CH3 O-acyl Br O 2-N-acetylaminohypoxanthine Br OH CH3 O-acyl Br O Thymine Cl H CH3 O-acyl Br O Uracil Cl H CH3 O-acyl Br O Guanine Cl H CH3 O-acyl Br O Cytosine Cl H CH3 O-acyl Br O Adenine Cl H CH3 O-acyl Br O Hypoxanthine Cl H CH3 O-acyl Br O 5-Fluorouracil Cl H CH3 O-acyl Br O 8-Fluoroguanine Cl H CH3 O-acyl Br O 5-Fluorocytosine Cl H CH3 O-acyl Br O 8-Fluoroadenine Cl H CH3 O-acyl Br O 2-Fluoroadenine Cl H CH3 O-acyl Br O 2, 8-Difluoroadenine Cl H CH3 O-acyl Br O 2-Fluorohypoxanthine Cl H CH3 O-acyl Br O 8-Fluorohypoxanthine Cl H CH3 O-acyl Br O 2, 8-Difluorohypoxanthine Cl H CH3 O-acyl Br O 2-Aminoadenine Cl H CH3 O-acyl Br O 2-Amino-8-fluoroadenine Cl H CH3 O-acyl Br O 2-Amino-8-fluorohypoxanthine Cl H CH3 O-acyl Br O 2-Aminohypoxanthine Cl H CH3 O-acyl Br O 2-N-acetylguanine Cl H CH3 O-acyl Br O 4-N-acetylcytosine Cl H CH3 O-acyl Br O 6-N-acetyladenine Cl H CH3 O-acyl Br O 2-N-acetyl-8-fluoroguanine Cl H CH3 O-acyl Br O 4-N-acetyl-5-fluorocytosine Cl H CH3 O-acyl Br O 6-N-acetyl-2-fluoroadenine Cl H CH3 O-acyl Br O 6-N-acetyl-2, 8-difluoroadenine Cl H CH3 O-acyl Br O 6-N-acetyl-2-aminoadenine Cl H CH3 O-acyl Br O 6-N-acetyl-2-amino-8-fluoroadenine Cl H CH3 O-acyl Br O 2-N-acetylaminoadenine C1 H CH3 O-acyl Br O 2-N-acetylamino-8-fluoroadenine Cl H CH3 O-acyl Br O 2-N-acetylamino-8-fluorohypoxanthine Cl H CH3 O-acyl Br O 2-N-acetylaminohypoxanthine Cl H CH3 O-acyl Br O Thymine Cl O-amino acid CH3 O-acyl Br O Uracil Cl O-amino acid CH3 O-acyl Br O Guanine Cl O-amino acid CH3 O-acyl Br O Cytosine Cl O-amino acid CH3 O-acyl Br O Adenine Cl 0-amino acid CH3 O-acyl Br O Hypoxanthine Cl O-amino acid CH3 O-acyl Br O 5-Fluorouracil Cl O-amino acid CH3 O-acyl Br O 8-Fluoroguanine Cl O-amino acid CH3 O-acyl Br O 5-Fluorocytosine Cl O-amino acid CH3 O-acyl Br O 8-Fluoroadenine Cl 0-amino acid CH3 O-acyl Br O 2-Fluoroadenine Cl O-amino acid R R R X Base Rl° R9 CH3 O-acyl Br O 2, 8-Difluoroadenine Cl O-amino acid CH3 O-acyl Br O 2-Fluorohypoxanthine Cl O-amino acid CH3 O-acyl Br O 8-Fluorohy oxanthine Cl O-amino acid CH3 O-acyl Br O 2, 8-Difluorohypoxanthine Cl O-amino acid CH3 0-acy) Br O 2-Aminoadenine Cl O-amino acid CH3 O-acyl Br O 2-Amino-8-fluoroadenine Cl O-amino acid CH3 O-acyl Br O 2-Amino-8-fluorohypoxanthine Cl 0-amino acid CH3 O-acyl Br O 2-Aminoh oxanthine Cl O-amino acid CH3 O-acyl Br O 2-N-acet 1 uanine Cl O-amino acid CH3 O-acyl Br O 4-N-acetylcytosine Cl O-amino acid CH3 O-acyl Br O 6-N-acet ladenine Cl O-amino acid CH3 O-acyl Br O 2-N-acetyl-8-fluoroguanine Cl O-amino acid CH3 O-acyl Br O 4-N-acetyI-5-fluorocytosine Cl O-amino acid CH3 O-acyl Br O 6-N-acetyl-2-fluoroadenine Cl O-amino acid CH3 O-acyl Br O 6-N-aceteI-2, 8-difluoroadenine Cl O-amino acid CH3 O-acyl Br O 6-N-acetyl-2-aminoadenine Cl O-amino acid CH3 O-acyl Br O 6-N-acetyl-2-amino-8-fluoroadenine Cl O-amino acid CH3 O-acyl Br O 2-N-acetylaminoadenine Cl O-amino acid CH3 O-acyl Br O 2-N-acetylamino-8-fluoroadenine Cl O-amino acid CH3 O-acyl Br O 2-N-acetylamino-8-fluorohypoxanthine Cl O-amino acid CH3 O-acyl Br O 2-N-acetylaminohypoxanthine Cl O-amino acid CH3 O-acyl Br O Th mine C1 O-acyl CH3 0-acyl Br 0 Uracil Cl 0-acyl CH3 O-acyl Br O Guanine Cl O-acyl CH3 O-acyl Br O Cytosine Cl O-acyl CH3 O-acyl Br O Adenine C I O-acyl CH3 O-acyl Br O Hypoxanthine Cl O-acyl CH3 O-acyl Br O 5-Fluorouracil Cl O-acyl S CH3 O-acyl Br O 8-Fluoroguanine Cl O-acyl CH3 O-acyl Br O 5-Fluoroc osine Cl O-ac 1 CH3 O-acyl Br O 8-Fluoroadenine Cl O-acyl CH3 O-acyl Br O 2-Fluoroadenine Cl O-acyl CH3 O-acyl Br O 2, 8-Difluoroadenine Cl O-acyl CH3 O-acyl Br O 2-Fluorohypoxanthine Cl O-acyl CH3 O-acyl Br O 8-Fluorohypoxanthine Cl O-ac I CH3 O-acyl Br O 2, 8-Difluorohypoxanthine Cl O-acyl CH3 O-acyl Br O 2-Aminoadenine Cl O-acyl CH3 O-acyl Br O 2-Amino-8-fluoroadenine Cl O-acyl CH3 O-acyl Br O 2-Amino-8-fluorohypoxanthine Cl O-acyl CH3 O-acyl Br O 2-Aminohypoxanthine Cl 0-acyl CH3 O-acyl Br O 2-N-acetylguanine C I O-acyl CH3 O-acyl Br O 4-N-acetylcytosine Cl O-acyl CH3 O-acyl Br O 6-N-acet ladenine Cl O-acyl CH3 O-acyl Br O 2-N-acetyl-8-fluoroguanine Cl O-acyl CH3 0-acy) Br O 4-N-acetyl-5-fluorocytosine Cl O-acyl CH3 0-acyl 1 Br O 6-N-acetyl-2-fluoroadenine Cl O-acyl CH3 O-acyl Br O 6-N-acetyl-2, 8-difluoroadenine Cl O-acyl R R R X Base'R R CH3 O-acyl Br O 6-N-acetyl-2-aminoadenine Cl O-acyl CH3 O-acyl Br O 6-N-acetyl-2-amino-8-fluoroadenine Cl 0-acyl CH3 O-acyl Br O 2-N-acetylaminoadenine Cl O-acyl CH3 O-acyl Br O 2-N-acetylamino-8-fluoroadenine Cl O-acyl CH3 O-acyl Br O 2-N-acetylamino-8-fluorohypoxanthine Cl O-acyl CH3 O-acyl Br O 2-N-acetylaminohypoxanthine Cl O-acyl CH3 O-acyl Br O Thymine Cl OH CH3 O-acyl Br O Uracil Cl OH CH3 O-acyl Br O Guanine Cl OH CH3 0-acyl Br 0 Cytosine Cl OH CH3 0-acyl Br O Adenine Cl OH CH3 O-acyl Br O Hypoxanthine Cl OH CH3 O-acyl Br O 5-Fluorouracil Cl OH CH3 O-acyl Br O 8-Fluoroguanine Cl OH CH3 O-acyl Br O 5-Fluorocytosine Cl OH CH3 O-acyl Br O 8-Fluoroadenine Cl OH CH3 O-acyl Br O 2-Fluoroadenine Cl OH CH3 O-acyl Br O 2, 8-Difluoroadenine Cl OH CH3 O-acyl Br O 2-Fluorohypoxanthine Cl OH CH3 O-acyl Br O 8-Fluoroh oxanthine Cl OH CH3 O-acyl Br O 2, 8-Difluorohypoxanthine Cl OH CH3 O-acyl Br O 2-Aminoadenine Cl OH CH3 O-acyl Br 0 2-Amino-8-fluoroadenine Cl OH CH3 O-acyl Br O 2-Amino-8-fluorohypoxanthine Cl OH CH3 O-acyl Br O 2-Aminohypoxanthine Cl OH CH3 O-acyl Br O 2-N-acetylguanine Cl OH CH3 O-acyl Br O 4-N-acetylcytosine Cl OH CH3 0-acyl Br O 6-N-acetyladenine Cl OH CH3 O-acyl Br O 2-N-acetyl-8-fluoroguanine Cl OH CH3 O-acyl Br O 4-N-acetyl-5-fluorocytosine Cl OH CH3 O-acyl Br O 6-N-acetyl-2-fluoroadenine C I OH CH3 O-acyl Br O 6-N-acetyl-2, 8-difluoroadenine Cl OH CH3 O-acyl Br O 6-N-acetyl-2-aminoadenine Cl OH CH3 0-acy) Br O 6-N-acetyl-2-amino-8-fluoroadenine Cl OH CH3 O-acyl Br O 2-N-acetylaminoadenine Cl OH CH3 O-acyl Br O 2-N-acetylamino-8-fluoroadenine C1 OH CH3 O-acyl Br O 2-N-acetylamino-8-fluorohypoxanthine Cl OH CH3 O-acyl Br O 2-N-acetylaminohypoxanthine Cl OH CH3 O-acyl Br O Thymine H H CH3 O-acyl Br O Uracil H H CH3 O-acyl Br O Guanine H H CH3 O-acyl Br O Cytosine H H CH3 O-acyl Br O Adenine H H CH3 O-acyl Br O Hypoxanthine H H CH3 O-acyl Br O 5-Fluorouracil H H CH3 O-acyl Br O 8-Fluoroguanine H H CH3 O-acyl Br O 5-Fluorocytosine H H R"X Base Rlo R9 CH3 0-aCYI Br 0 8-Fluoroadenine H H CH3 0-acyl Br 0 2-Fluoroadenine H H CH3 O-acyl Br O 2-Fluoroadenine H H CH3 0-acyl Br 0 2, 8-Difluoroadenine H H CH3 O-acyl Br O 2-Fluorohypoxanthine H H CH3 O-acyl Br O 8-Fluorohypoxanthine H H CH3 O-acyl Br O 2, 8-Difluorohypoxanthine H H CH3 O-acyl Br O 2-Aminoadenine H H CH3 O-acyl Br O 2-Amino-8-fluoroadenine H H CH3 O-acyl Br O 2-Amino-8-fluoroh oxanthine H H CH3 O-acyl Br O 2-Aminohypoxanthine H H CH3 O-acyl Br O 2-N-acetylguanine H H CH3 O-acyl Br O 4-N-acetylcytosine H H CH3 O-acyl Br O 6-N-acetyladenine H H CH3 O-acyl Br O 2-N-acetyl-8-fluoroguanine H H CH3 O-acyl Br O 4-N-acetyl-5-fluorocytosine H H CH3 O-acyl Br O 6-N-acet 1-2-fluoroadenine H H CH3 O-acyl Br O 6-N-acetyl-2, 8-difluoroadenine H H CH3 O-acyl Br O 6-N-aceteI-2-am inoadenine H H CH3 O-acyl Br O 6-N-acetyl-2-amino-8-fluoroadenine H H CH3 0-acyl Br 0 2-N-acetylaminoadenine H H CH3 O-acyl Br O 2-N-acetylamino-8-fluoroadenine H H CH3 O-acyl Br O 2-N-acetylamino-8-fluorohypoxanthine H H CH3 0-acyl Br 0 2-N-acetylaminohypoxanthine H H CH3 O-acyl Br O Thymine H O-amino acid CH3 O-acyl Br O Uracil H O-amino acid CH3 O-acyl Br O Guanine H O-amino acid CH3 O-acyl Br O Cytosine H 0-amino acid CH3 O-acyl Br O Adenine H O-amino acid CH3 O-acyl Br O Hypoxanthine H 0-amino acid CH3 O-acyl Br O 5-Fluorouracil H 0-amino acid CH3 O-acyl Br O 8-Fluoroguanine H O-amino acid CH3 O-acyl Br O 5-Fluorocytosine H O-amino acid CH3 O-acyl Br O 8-Fluoroadenine H O-amino acid CH3 O-acyl Br O 2-Fluoroadenine H O-amino acid CH3 O-acyl Br O 2, 8-Difluoroadenine H O-amino acid CH3 O-acyl Br O 2-Fluorohypoxanthine H O-amino acid CH3 O-acyl Br O 8-Fluoroh oxanthine H O-amino acid CH3 0-acyl Br 0 2, 8-Difluorohypoxanthine H 0-amino acid CH3 0-acyl Br O 2-Aminoadenine H O-amino acid CH3 O-acyl Br O 2-Amino-8-fluoroadenine H O-amino acid CH3 O-acyl Br O 2-Amino-8-fluorohypoxanthine H O-amino acid CH3 O-acyl Br O 2-Aminohypoxanthine H O-amino acid CH3 O-acyl Br O 2-N-acet lguanine H O-amino acid CH3 O-acyl Br O 4-N-acetylcytosine H O-amino acid CH3 O-acyl Br O 6-N-acetyladenine H 0-amino acid CH3 0-acyl Br 0 2-N-acetyl-8-fluoroguanine H 0-amino acid CH3 O-acyt Br O 4-N-acetyl-5-fluorocytosine H O-amino acid R"R R"X Base R Ry CH3 O-acyl Br O 6-N-acetyl-2-fluoroadenine H O-amino acid CH3 O-acyl Br O 6-N-acetyl-2, 8-difluoroadenine H O-amino acid CH3 O-acyl Br O 6-N-acetyl-2-aminoadenine H O-amino acid CH3 O-acyl Br O 6-N-acetyl-2-amino-8-fluoroadenine H O-amino acid CH3 O-acyl Br O 2-N-acetylaminoadenine H O-amino acid CH3 O-acyl Br O 2-N-acetylamino-8-fluoroadenine H O-amino acid CH3 O-acyl Br O 2-N-acetylamino-8-fluorohypoxanthine H O-amino acid CH3 O-acyl Br O 2-N-acetylaminohypoxanthine H O-amino acid CH3 O-acyl Br O Thymine H O-ac 1 CH3 O-acyl Br O Uracil H O-acyl CH3 O-acyl Br O Guanine H O-ac 1 CH3 O-acyl Br O Cytosine H 0-acyl CH3 O-acyl Br O Adenine H O-acyl CH3 O-acyl Br O Hypoxanthine H O-acyl CH3 O-acyl Br O 5-Fluorouracil H O-acyl CH3 O-acyl Br O 8-Fluoroguanine H O-acyl CH3 O-acyl Br O 5-Fluorocytosine H O-acyl CH3 0-acy) Br O 8-Fluoroadenine H O-acyl CH3 O-acyl Br O 2-Fluoroadenine H O-acyl CH3 O-acyl Br O 2, 8-Difluoroadenine H O-acyl CH3 O-acyl Br O 2-Fluorohypoxanthine H O-acyl CH3 O-acyl Br O 8-Fluoroh oxanthine H O-acyl CH3 O-acyl Br O 2, 8-Difluorohypoxanthine H O-acyl CH3 O-acyl Br O 2-Aminoadenine H O-acyl CH3 O-acyl Br O 2-Amino-8-fluoroadenine H O-acyl CH3 O-acyl Br O 2-Amino-8-fluorohypoxanthine H O-acyl CH3 0-acy) Br O 2-Aminohypoxanthine H O-acyl CH3 0-acy) Br O 2-N-acetylguanine H 0-acyl CH3 O-acyl Br O 4-N-acetylcytosine H O-acyl CH3 O-acyl Br O 6-N-acet ladenine H O-acyl CH3 O-acyl Br O 2-N-acetyl-8-fluoroguanine H O-acyl CH3 O-acyl Br O 4-N-acetyl-5-fluorocytosine H O-acyl CH3 O-acyl Br O 6-N-acetyl-2-fluoroadenine H 0-acyl CH3 O-acyl Br O 6-N-acetyl-2, 8-difluoroadenine H O-acyl CH3 O-acyl Br O 6-N-acetyl-2-aminoadenine H O-acyl CH3 O-acyl Br O 6-N-acetyl-2-amino-8-fluoroadenine H O-acyl CH3 O-acyl Br O 2-N-acetylaminoadenine H O-acyl CH3 O-acyl Br O 2-N-acetylamino-8-fluoroadenine H O-acyl CH3 O-acyl Br O 2-N-acetylamino-8-fluorohypoxanthine H O-acyl CH3 O-acyl Br O 2-N-acetylaminohypoxanthine H 0-acyl CH3 O-acyl Br O Thymine H OH CH3 O-acyl Br O Uracil H OH CH3 O-acyl Br O Guanine H OH CH3 O-acyl Br O Cytosine H OH CH3 O-acyl Br O Adenine H OH CH3 O-acyl Br O Hypoxanthine H OH CH3 O-acyl Br O 5-Fluorouracil H OH R° R'R X Base Rl° R9 CH3 O-acyl Br O 8-Fluoroguanine H OH CH3 O-acyl Br O 5-Fluorocytosine H OH CH3 O-acyl Br O 8-Fluoroadenine H OH CH3 O-acyl Br O 2-Fluoroadenine H OH CH3 O-acyl Br O 2, 8-Difluoroadenine H OH CH3 O-acyl Br O 2-Fluorohypoxanthine H OH CH3 O-acyl Br O 8-Fluorohypoxanthine H OH CH3 O-acyl Br O 2, 8-Difluorohypoxanthine H OH CH3 O-acyl Br O 2-Aminoadenine H OH CH3 O-acyl Br O 2-Amino-8-fluoroadenine H OH CH3 O-acyl Br O 2-Amino-8-fluorohypoxanthine H OH CH3 O-acyl Br O 2-Aminohypoxanthine H OH CH3 O-acyl Br O 2-N-acetyl guanine H OH CH3 O-acyl Br O 4-N-acetylcytosine H OH CH3 O-acyl Br O 6-N-acetyladenine H OH CH3 O-acyl Br O 2-N-acetyl-8-fluoroguanine H OH CH3 O-acyl Br O 4-N-acetyl-5-fluorocytosine H OH CH3 O-acyl Br O 6-N-acetyl-2-fluoroadenine H OH CH3 O-acyl Br O 6-N-acetyl-2, 8-difluoroadenine H OH CH3 0-acyl Br O 6-N-acetyl-2-aminoadenine H OH CH3 O-acyl Br O 6-N-acetyl-2-amino-8-fluoroadenine H OH CH3 O-acyl Br O 2-N-acetylaminoadenine H OH CH3 O-acyl Br O 2-N-acetylamino-8-fluoroadenine H OH CH3 O-acyl Br O 2-N-acetylamino-8-fluorohypoxanthine H OH CH3 O-acyl Br O 2-N-acetylaminohypoxanthine H OH CH3 0-acyl Br O Thymine OH H CH3 0-acyl Br O Uracil OH H CH3 O-acyl Br O Guanine OH H CH3 O-acyl Br O Cytosine OH H CH3 O-acyl Br O Adenine OH H CH3 0-acryl Br O Hypoxanthine OH H CH3 O-acyl Br O 5-Fluorouracil OH H CH3 0-acryl Br O 8-Fluoroguanine OH H CH3 O-acyl Br O 5-Fluorocetosine OH H CH3 O-acyl Br O 8-Fluoroadenine OH H CH3 O-acyl Br O 2-Fluoroadenine OH H CH3 O-acyl Br O 2, 8-Difluoroadenine OH H CH3 O-acyl Br O 2-Fluorohypoxanthine OH H CH3 O-acyl Br O 8-Fluorohypoxanthine OH H CH3 O-acyl Br O 2, 8-Difluorohypoxanthine OH H. CH3 O-acyl Br O 2-Aminoadenine OH H CH3 O-acyl Br O 2-Amino-8-fluoroadenine OH H CH3 O-acyl Br O 2-Amino-8-fluorohypoxanthine OH H CH3 O-acyl Br O 2-Aminohypoxanthine OH H CH3 O-acyl Br O 2-N-acetyl uanine OH H CH3 O-acyl Br O 4-N-acetylcytosine OH H CH3 O-acyl Br O 6-N-acetyladenine OH H R"R'R° X Base R R CH3 0-acyl Br O 2-N-acetyl-8-fluoroguanine OH H CH3 0-acyl Br 0 4-N-acetyl-5-fluorocytosine OH H CH3 0-acyl Br O 6-N-acetyl-2-fluoroadenine OH H CH3 O-acyl Br O 6-N-acetyl-2, 8-difluoroadenine OH H CH3 O-acyl Br O 6-N-acetyl-2-aminoadenine OH H CH3 O-acyl Br O 6-N-acetyl-2-amino-8-fluoroadenine OH H CH3 O-acyl Br O 2-N-acetylaminoadenine OH H CH3 O-acyl Br O 2-N-acetylamino-8-fluoroadenine OH H CH3 O-acyl Br O 2-N-acetylamino-8-fluorohypoxanthine OH H CH3 O-acyl Br O 2-N-acetylaminohypoxanthine OH H CH3 O-acyl Cl O Thymine F H CH3 O-acyl Cl O Uracil F H CH3 0-acyl Cl 0 Guanine F H CH3 O-acyl Cl 0 Cytosine F H CH3 0-acyl Cl 0 Adenine F H CH3 O-acyl Cl 0 Hypoxanthine F H CH3 O-acyl Cl O 5-Fluorouracil F H CH3 O-acyl Cl O 8-Fluoroguanine F H CH3 O-acyl Cl O 5-Fluorocytosine F H CH3 0-acyl Cl 0 8-Fluoroadenine F H CH3 O-acyl Ci O 2-Fluoroadenine F H CH3 O-acyl Ci O 2, 8-Difluoroadenine F H CH3 O-acyl Cl O 2-Fluorohypoxanthine F H CH3 O-acyl Cl O 8-Fluorohypoxanthine F H CH3 O-acyl Ci O 2, 8-Difluorohypoxanthine F H CH3 O-acyl C1 O 2-Aminoadenine F H CH3 O-acyl Cl O 2-Amino-8-fluoroadenine F H CH3 O-acyl Cl O 2-Amino-8-fluorohypoxanthine F H CH3 O-acyl Cl O 2-Aminohypoxanthine F H CH3 O-ac 1 Cl O 2-N-acetylguanine F H CH3 O-ac 1 CI O 4-N-acetylcytosine F H CH3 O-acyl Cl O 6-N-acetyladenine F H CH3 O-acyl Cl O 2-N-acetyl-8-fluoroguanine F H CH3 O-acyl Cl O 4-N-acetyl-5-fluorocytosine F H CH3 O-acyl Cl O 6-N-acetyl-2-fluoroadenine F H CH3 O-acyl Cl O 6-N-acetyl-2, 8-difluoroadenine F H CH3 O-acyl Cl O 6-N-acetyl-2-aminoadenine F H CH3 O-acyl Cl O 6-N-acetyl-2-amino-8-fluoroadenine F H CH3 0-acyl Cl 0 2-N-acetylaminoadenine F H CH3 O-acyl Cl O 2-N-acetylamino-8-fluoroadenine F H CH3 O-acyl Cl O 2-N-acetylamino-8-fluorohypoxanthine F H CH3 O-acyl Cl O 2-N-acetylaminohypoxanthine F H CH3 O-acyl Cl O Thymine F O-amino acid CH3 O-acyl Cl O Uracil F O-amino acid CH3 O-acyl Cl O Guanine F O-amino acid CH3 0-acyl Cl 0 Cytosine F 0-amino acid CH3 O-acyl Cl O Adenine F O-amino acid R R R° X Base R R CH3 O-acyl Cl O Hypoxanthine F O-amino acid CH3 O-acyl Cl O 5-Fluorouracil F O-amino acid CH3 O-acyl Cl O 8-Fluoroguanine F O-amino acid CH3 O-acyl Cl O 5-Fluorocytosine F O-amino acid CH3 O-acyl Cl O 8-Fluoroadenine F O-amino acid CH3 O-acyl Cl O 2-Fluoroadenine F O-amino acid CH3 0-acyl ci 0 2, 8-Difluoroadenine F O-amino acid CH3 O-acyl Cl O 2-Fluorohypoxanthine F O-amino acid CH3 O-acyl Cl O 8-Fluorohy oxanthine F O-amino acid CH3 O-acyl Cl O 2, 8-Difluorohypoxanthine F 0-amino acid CH3 0-acyl Cl 0 2-Aminoadenine F 0-amino acid CH3 O-acyl Cl O 2-Amino-8-fluoroadenine F O-amino acid CH3 O-acyl Cl O 2-Amino-8-fluorohypoxanthine F O-amino acid CH3 O-acyl Cl O 2-Aminohypoxanthine F O-amino acid CH3 O-acyl Cl O 2-N-acetylguanine F O-amino acid CH3 O-acyl Cl O 4-N-acetylcytosine F O-amino acid CH3 O-acyl Cl O 6-N-acetyladenine F O-amino acid CH3 O-acyl Cl O 2-N-acetyl-8-fluoroguanine F O-amino acid CH3 O-acyl Cl O 4-N-acetyl-5-fluorocytosine F O-amino acid CH3 O-acyl Cl O 6-N-acetyl-2-fluoroadenine F O-amino acid CH3 O-acyl Cl O 6-N-acetyl-2, 8-difluoroadenine F O-amino acid CH3 O-acyl Cl O 6-N-acetyl-2-aminoadenine F O-amino acid CH3 O-acyl Cl O 6-N-acetyl-2-amino-8-fluoroadenine F O-amino acid CH3 O-acyl Cl O 2-N-acetylaminoadenine F O-amino acid CH3 O-acyl Cl O 2-N-acetylamino-8-fluoroadenine F O-amino acid CH3 O-acyl Cl O 2-N-acetylamino-8-fluorohypoxanthine F O-amino acid CH3 O-acyl Cl O 2-N-acetylaminohypoxanthine F O-amino acid CH3 O-acyl Cl O Thymine F O-acyl CH3 O-acyl Cl O Uracil F O-acyl CH3 O-acyl Cl O Guanine F O-acyl CH3 0-acyl Cl 0 Cytosine F 0-acyl CH3 O-acyl Cl O Adenine F O-acyl CH3 O-acyl Cl O Hypoxanthine F O-acyl CH3 O-ac 1 Cl O 5-Fluorouracil F O-acyl CH3 O-acyl Cl O 8-Fluoroguanine F O-acyl CH3 O-acyl Cl O 5-Fluorocytosine F O-acyl CH3 O-acyl Cl O 8-Fluoroadenine F O-acyl CH3 O-acyl Cl O 2-Fluoroadenine F O-acyl CH3 O-acyl Cl O 2, 8-Difluoroadenine F O-acyl CH3 O-acyl Cl O 2-Fluorohypoxanthine F O-acyl CH3 0-acyl Cl O 8-Fluorohypoxanthine F O-acyl CH3 O-acyl CI O 2, 8-Difluorohypoxanthine F O-acyl CH3 O-acyl Cl O 2-Aminoadenine F O-acyl CH3 O-acyl Cl O 2-Amino-8-fluoroadenine F O-acyl CH3 O-acyI CI O 2-Amino-8-fluorohypoxanthine F O-acyl CH3 O-acyl CI O 2-Aminohypoxanthine F O-acyl CH3 0-acyl Cl 0 2-N-acetylguanine F 0-acyl R6 R7 R8 X Base F R9 CH3 O-acyl Cl O 4-N-acetylcytosine F O-acyl CH3 O-ac 1 Cl O 6-N-acetyladenine F O-acyl CH3 O-acyl Cl O 2-N-acetyl-8-fluoroguanine F O-acyl CH3 O-acyl Cl O 4-N-acetyl-5-fluorocytosine F O-acyl CH3 O-acyl CI O 6-N-acetyl-2-fluoroadenine F O-acyl CH3 O-acyl Cl O 6-N-acetyl-2, 8-difluoroadenine F O-acyl CH3 O-acyl Cl O 6-N-acetyl-2-aminoadenine F O-acyl CH3 O-acyl Cl O 6-N-acetyl-2-amino-8-fluoroadenine F O-acyl CH3 O-acyl Cl O 2-N-acetylaminoadenine F O-acyl CH3 O-acyl Cl O 2-N-acetylamino-8-fluoroadenine F O-acyl CH3 O-acyl Cl O 2-N-acetylamino-8-fluorohypoxanthine F O-acyl- CH3 O-acyl Cl O 2-N-acetylaminohypoxanthine F O-acyl CH3 O-acyl Cl O Thymine F OH CH3 O-acyl Cl O Uracil F OH CH3 O-acyl Cl O Guanine F OH CH3 O-acyl C1 O C osine F OH CH3 O-acyl Cl O Adenine F OH CH3 O-acyl ci O Hypoxanthine F OH CH3 O-acyl Cl O 5-Fluorouracil F OH CH3 O-acyl Cl O 8-Fluoroguanine F OH CH3 O-acyl Cl O 5-Fluorocytosine F OH CH3 O-acyl C I O 8-Fluoroadenine F OH CH3 O-acyl Cl O 2-Fluoroadenine F OH CH3 O-acyl Cl O 2, 8-Difluoroadenine F OH CH3 O-acyl Cl O 2-Fluorohy oxanthine F OH CH3 O-ac 1 CI O 8-Fluoroh oxanthine F OH CH3 O-acyl Cl O 2, 8-Difluorohypoxanthine F OH CH3 O-acyl Cl O 2-Aminoadenine F OH CH3 O-acyl Cl O 2-Amino-8-fluoroadenine F OH CH3 O-acyl Cl O 2-Amino-8-fluorohypoxanthine F OH CH3 0-acyl Cl 0 2-Aminohypoxanthine F OH CH3 O-acyl Cl O 2-N-acetylguanine F OH CH3 0-acyl Cl 0 4-N-acetylcytosine F OH CH3 O-acyl Cl O 6-N-acet ladenine F OH CH3 O-acyl Cl O 2-N-acetyl-8-fluoroguanine F OH CH3 O-acyl C1 O 4-N-acetyl-5-fluorocytosine F OH CH3 O-acyl Cl O 6-N-acetyl-2-fluoroadenine F OH CH3 O-acyl Cl O 6-N-acetyl-2, 8-difluoroadenine F OH CH3 O-acyl Cl O 6-N-acetyl-2-aminoadenine F OH CH3 O-acyl Cl O 6-N-acetyl-2-amino-8-fluoroadenine F OH CH3 O-acyl Cl O 2-N-acetylaminoadenine F OH CH3 O-acyl Cl O 2-N-acetylamino-8-fluoroadenine F OH CH3 O-acyl Cl O 2-N-acetylamino-8-fluorohypoxanthine F OH CH3 O-acyl Cl O 2-N-acetylaminohypoxanthine F OH CH3 O-acyl Cl O Thymine Br H CH3 O-acyl Cl O Uracil Br H CH3 O-acyl Cl O Guanine Br H F R7 RX X Base R R9 CH3 O-acyl Cl O Cytosine Br H CH3 O-acyl Cl O Adenine Br H CH3 O-acyl Cl O Hypoxanthine Br H CH3 O-acyl Cl O 5-Fluorouracil Br H CH3 O-acyl Cl O 8-Fluoroguanine Br H CH3 O-acyl Cl O 5-Fluorocytosine Br H CH3 O-acyl Cl O 8-Fluoroadenine Br H CH3 O-acyl Cl O 2-Fluoroadenine Br H CH3 O-acyl Cl O 2, 8-Difluoroadenine Br H CH3 O-acyl Cl O 2-Fluorohypoxanthine Br H CH3 O-acyl Cl O 8-Fluorohypoxanthine Br H CH3 O-acyl Cl O 2, 8-Difluorohypoxanthine Br H CH3 O-acyl Cl O 2-Aminoadenine Br H CH3 O-acyl Cl O 2-Amino-8-fluoroadenine Br H CH3 0-acyl Cl 0 2-Amino-8-fluorohypoxanthine Br H CH3 O-acyl Cl O 2-Aminohypoxanthine Br H CH3 O-acyl Cl 0 2-N-acetylguanine Br H CH3 O-acyl Cl O 4-N-acetylcytosine Br H CH3 0-acyl Cl O 6-N-acetyladenine Br H CH3 O-acyl Cl O 2-N-acetyl-8-fluoroguanine Br H CH3 O-acyl Cl O 4-N-acetyl-5-fluorocytosine Br H CH3 0-acyl Cl 0 6-N-acetyl-2-fluoroadenine Br H CH3 O-acyl Cl 0 6-N-acetyl-2, 8-difluoroadenine Br H CH3 O-acyl CI O 6-N-acetyl-2-aminoadenine Br H CH3 O-ac 1 C1 O 6-N-acetyl-2-amino-8-fluoroadenine Br H CH3 O-acyl Cl O 2-N-acetylaminoadenine Br H CH3 O-acyl Cl O 2-N-acetylamino-8-fluoroadenine Br H CH3 O-acyl Cl O 2-N-acetylamino-8-fluorohypoxanthine Br H CH3 O-acyl Cl O 2-N-acetylaminohypoxanthine Br H CH3 O-acyl Cl O Thymine Br O-amino acid CH3 O-acyl Cl O Uracil Br O-amino acid CH3 O-acyl Cl O Guanine Br O-amino acid CH3 O-acyl Cl O Cytosine Br O-amino acid CH3 O-acyl Cl O Adenine Br O-amino acid CH3 o-acyl Cl O Br O-amino acid CH3 O-acyl Cl O 5-Fluorouracil Br O-amino acid CH3 O-acyl Cl O 8-Fluoroguanine Br O-amino acid CH3 O-acyl Cl O 5-Fluorocytosine Br O-amino acid CH3 O-acyl Cl O 8-Fluoroadenine Br O-amino acid CH3 O-acyl Cl O 2-Fluoroadenine Br O-amino acid CH3 O-acyl Cl O 2, 8-Difluoroadenine Br O-amino acid CH3 O-acyl Cl O 2-Fluorohypoxanthine Br O-amino acid CH3 O-acyl Cl O 8-Fluorohypoxanthine Br O-amino acid CH3 0-acyl Cl O 2, 8-Difluorohypoxanthine Br 0-amino acid CH3 O-acyl Cl O 2-Aminoadenine Br O-amino acid CH3 O-acyl Cl O 2-Amino-8-fluoroadenine Br O-amino acid CH3 O-acyl Cl O 2-Amino-8-fluorohypoxanthine Br O-amino acid R R'R X Base R R CH3 O-ac 1 C1 O 2-Aminoh oxanthine Br O-amino acid CH3 O-acyl Cl O 2-N-acetylguanine Br O-amino acid CH3 O-acyl Cl O 4-N-acetylcytosine Br O-amino acid CH3 O-acyl CI O 6-N-acetyladenine Br O-amino acid CH3 O-acyl Cl O 2-N-acetyl-8-fluoroguanine Br O-amino acid CH3 O-acyl Cl O 4-N-acetyl-5-fluorocytosine Br O-amino acid CH3 O-acyl Cl O 6-N-acetyl-2-fluoroadenine Br O-amino acid CH3 O-ac 1 C1 O 6-N-acet 1-2, 8-difluoroadenine Br O-amino acid CH3 O-ac 1 C1 O 6-N-acet 1-2-aminoadenine Br O-amino acid CH3 0-acyl Cl 0 6-N-acetyl-2-amino-8-fluoroadenine Br O-amino acid CH3 O-acyl Cl O 2-N-acetylaminoadenine Br O-amino acid CH3 O-acyl ci 0 2-N-acetylamino-8-fluoroadenine Br O-amino acid CH3 O-acyl Cl O 2-N-acetylamino-8-fluorohypoxanthine Br O-amino acid CH3 O-acyl Cl O 2-N-acetylaminohypoxanthine Br O-amino acid CH3 O-acyl Cl O Thymine Br O-acY CH3 O-acyl Cl O Uracil Br O-acyl CH3 O-acyl Cl O Guanine Br O-acyl CH3 O-acyl Cl O Cytosine Br O-acyl CH3 O-acyl Cl O Adenine Br O-acyl CH3 O-acyl Cl O Hypoxanthine Br O-acyl CH3 0-acyl Cl 0 5-Fluorouracil Br 0-acyl CH3 O-acyl Cl O 8-Fluoroguanine Br O-acyl CH3 O-acyl Cl O 5-Fluorocytosine Br O-acyl CH3 O-acyl Cl O 8-Fluoroadenine Br O-acyl CH3 O-acyl Cl O 2-Fluoroadenine Br O-acyl CH3 O-acyl Cl O 2, 8-Difluoroadenine Br O-acyl CH3 O-acyl Cl O 2-Fluorohypoxanthine Br O-acyl CH3 O-acyl Cl O 8-Fluorohypoxanthine Br O-acyl CH3 O-acyl Cl O 2, 8-Difluorohypoxanthine Br O-acyl CH3 O-acyl Cl O 2-Aminoadenine Br O-acyl CH3 O-acyl'Cl O 2-Amino-8-fluoroadenine Br O-acyl CH3 O-acyl Cl O 2-Amino-8-fluorohypoxanthine Br O-acyl CH3 O-ac 1 C1 O 2-Aminoh oxanthine Br O-ac 1 CH3 O-acyl Cl O 2-N-acetylguanine Br O-acyl CH3 O-acyl Cl O 4-N-acetylcytosine Br O-acyl CH3 O-acyl Cl O 6-N-acetyladenine Br O-acyl CH3 O-acyl Cl O 2-N-acetyl-8-fluoroguanine Br O-acyl CH3 O-acyl Cl O 4-N-acetyl-5-fluorocytosine Br O-acyl CH3 O-acyl Cl O 6-N-acetyl-2-fluoroadenine Br O-acyl CH3 O-acyl Cl O 6-N-acetyl-2, 8-difluoroadenine Br O-acY CH3 O-acyl Cl O 6-N-acetyl-2-aminoadenine Br O-acyl CH3 O-acyl Cl O 6-N-acetyl-2-amino-8-fluoroadenine Br O-acyl CH3 0-acyl Cl 0 2-N-acetylaminoadenine Br 0-acyl CH3 O-acyl Cl O 2-N-acetylamino-8-fluoroadenine Br O-acyl CH3 O-acyl Cl O 2-N-acetylamino-8-fluorohypoxanthine Br 0-acyl CH3 O-ac 1 C1 O 2-N-acet laminoh oxanthine Br O-ac 1 CH3 O-acyl Cl O Thymine Br OH R R R X Base Rl° R9 CH3 O-acyl Cl O Uracil Br OH CH3 O-acyl Cl O Guanine Br OH CH3 0-acyl Cl 0 Cytosine Br OH CH3 O-acyl Cl O Adenine Br OH CH3 O-acyl Cl O Hypoxanthine Br OH CH3 O-acyl Cl O 5-Fluorouracil Br OH CH3 O-acyl Cl O 8-Fluoroguanine Br OH CH3 O-acyl Cl O 5-Fluorocytosine Br OH CH3 O-acyl Cl O 8-Fluoroadenine Br OH CH3 O-acyl Cl O 2-Fluoroadenine Br OH CH3 O-acyl Cl O 2, 8-Difluoroadenine Br OH CH3 O-acyl Cl O 2-Fluorohypoxanthine Br OH CH3 O-acyl Cl O 8-Fluorohypoxanthine Br OH CH3 O-acyl Cl O 2, 8-Difluorohypoxanthine Br OH CH3 0-acyl Cl 0 2-Aminoadenine Br OH CH3 O-acyl Cl O 2-Amino-8-fluoroadenine Br OH CH3 O-acyl Cl O 2-Amino-8-fluorohypoxanthine Br OH CH3 O-acyl Cl O 2-Aminohypoxanthine Br OH CH3 O-acyl Cl O 2-N-acetylguanine Br OH CH3 O-ac 1 Cl O 4-N-acet lcytosine Br OH CH3 O-acyl Cl O 6-N-acetyladenine Br OH CH3 O-acyl Cl O 2-N-acetyl-8-fluoroguanine Br OH CH3 O-acyl Cl O 4-N-acetyl-5-fluorocytosine Br OH CH3 O-acyl Cl O 6-N-acetyl-2-fluoroadenine Br OH CH3 O-acyl Cl O 6-N-acetyl-2, 8-difluoroadenine Br OH CH3 O-acyl Cl O 6-N-acetyl-2-aminoadenine Br OH CH3 O-acyl Cl O 6-N-acetyl-2-amino-8-fluoroadenine Br OH CH3 O-acyl Cl O 2-N-acetylaminoadenine Br OH CH3 O-acyl Cl O 2-N-acetylamino-8-fluoroadenine Br OH CH3 O-acyl Cl O 2-N-acetylamino-8-fluorohypoxanthine Br OH CH3 O-acyl Cl O 2-N-acetylaminohypoxanthine Br OH CH3 O-acyl Cl O Thymine Cl H CH3 O-acyl Cl O Uracil Cl H CH3 O-acyl Cl O Guanine Cl H CH3 O-acyl Cl O Cytosine C1 H CH3 O-acyl Cl O Adenine Cl H CH3 O-acyl Cl O Hypoxanthine Cl H CH3 O-acyl Cl O 5-Fluorouracil Cl H CH3 O-acyl Cl O 8-Fluoroguanine Cl H CH3 O-acyl C I O 5-F luorocytos ine C I H CH3 O-acyl Cl O 8-Fluoroadenine Cl H CH3 O-acyl Cl O 2-Fluoroadenine Cl H CH3 O-acyl Cl O 2, 8-Difluoroadenine Cl H CH3 O-acyl Cl O 2-Fluorohypoxanthine Cl H CH3 O-acyl Cl O 8-Fluorohypoxanthine Cl H CH3 O-acyl Cl O 2, 8-Difluorohypoxanthine Cl H CH3 0-acyl 0 2-Aminoadenine Cl H R6 R7 R8 X Base Rl° R9 CH3 0-acyl Cl O 2-Amino-8-fluoroadenine Cl H CH3 O-acyl Cl O 2-Amino-8-fluorohypoxanthine Cl H CH3 O-acyl Cl O 2-Aminohypoxanthine Cl H CH3 O-acyl Cl O 2-N-acetylguanine 0 Cl H CH3 O-acyl Cl O 4-N-acetylcytosine Cl H CH3 O-acyl Cl O 6-N-acetyladenine Cl H CH3 O-acyl CI O 2-N-acetyl-8-fluoroguanine Cl H CH3 O-acyl Cl O 4-N-acetyl-5-fluorocytosine Cl H CH3 O-acyl Cl O 6-N-acetyl-2-fluoroadenine Cl H CH3 O-acyl Cl O 6-N-acetyl-2, 8-difluoroadenine Cl H CH3 O-acyl Cl O 6-N-acetyl-2-aminoadenine Cl H CH3 O-acyl Cl O 6-N-acetyl-2-amino-8-fluoroadenine Cl H CH3 O-acyl C1 O 2-N-acetylaminoadenine Cl H CH3 O-acyl Cl O 2-N-acetylamino-8-fluoroadenine Cl H CH3 O-acyl Cl O 2-N-acetylamino-8-fluorohypoxanthine Cl H CH3 O-acyl Cl O 2-N-acetylaminohypoxanthine Cl H CH3 0-acyl Cl 0 Thymine Cl 0-amino acid CH3 O-acyl Cl O Uracil Cl O-amino acid CH3 O-a Cl O Guanine Cl O-amino acid CH3 O-acyl ci O Cytosine C1 O-amino acid CH3 O-acyl Cl O Adenine Cl O-amino acid CH3 O-acyl Cl O Hypoxanthine Cl O-amino acid CH3 O-acyl Cl O 5-Fluorouracil Cl O-amino acid CH3 O-acyl Cl O 8-Fluoroguanine Cl O-amino acid CH3 O-acyl Cl O 5-Fluorocytosine Cl O-amino acid CH3 O-acyl Cl O 8-Fluoroadenine Cl O-amino acid CH3 O-ac 1 C1 O 2-Fluoroadenine CI O-amino acid CH3 0-acyl Cl 0 2, 8-Difluoroadenine Cl 0-amino acid CH3 O-acyl Cl O 2-Fluorohypoxanthine CI O-amino acid CH3 O-acyl Cl O 8-Fluorohypoxanthine Cl O-amino acid CH3 O-acyl Cl O 2, 8-Difluorohypoxanthine Cl O-amino acid CH3 O-acyl Cl O 2-Aminoadenine CI O-amino acid CH3 O-acyl Cl O 2-Amino-8-fluoroadenine Cl O-amino acid CH3 O-acyl Cl O 2-Amino-8-fluorohypoxanthine Cl O-amino acid CH3 O-acyl Cl O 2-Aminohypoxanthine Cl O-amino acid CH3 O-acyl Cl O 2-N-acetylguanine Cl O-amino acid CH3 O-acyl Cl O 4-N-acetylcytosine Cl O-amino acid CH3 O-acyl Cl O 6-N-acetyladenine Cl O-amino acid CH3 O-ac 1 CI O 2-N-acetyl-8-fluoroguanine Cl O-amino acid CH3 O-acyl Cl O 4-N-acetyl-5-fluorocytosine Cl O-amino acid CH3 O-acyl Cl O 6-N-acetyl-2-fluoroadenine Cl O-amino acid CH3 O-acyl Cl O 6-N-acetyl-2, 8-difluoroadenine Cl O-amino acid CH3 O-acyl Cl O 6-N-acetyl-2-aminoadenine Cl O-amino acid CH3 O-acyl Cl O 6-N-acetyl-2-amino-8-fluoroadenine Cl O-amino acid CH3 O-acyl I Cl O 2-N-acetylaminoadenine Cl O-amino acid CH3 O-acyl C1 O 2-N-acet lamino-8-fluoroadenine C1 O-amino acid CH3 O-acyl Cl O 2-N-acetylamino-8-fluorohypoxanthine Cl O-amino acid R6 R R X Base R R CH3 O-acyl Cl O 2-N-acetylaminohypoxanthine Cl O-amino acid CH3 O-acyl Cl O Thymine Cl O-acyl CH3 O-acyl Cl O Uracil Cl O-acyl CH3 0-acyl Cl 0 Guanine Cl 0-acyl CH3 O-ac I Cl O C osine C1 O-ac 1 CH3 O-acyl Cl O Adenine Cl O-acyl CH3 O-acyl Cl O Hypoxanthine Cl O-acyl CH3 O-acyl Cl O 5-Fluorouracil Cl O-acyl CH3 O-acyl Cl O 8-Fluoroguanine Cl O-acyl CH3 O-acyl Cl O 5-Fluorocytosine Cl O-acyl CH3 O-acyl Cl O 8-Fluoroadenine Cl O-acyl CH3 O-acyl Cl O 2-Fluoroadenine Cl O-acyl CH3 0-acyl Cl 0 2, 8-Difluoroadenine Cl O-acyl CH3 O-acyl Cl O 2-Fluorohypoxanthine Cl O-acyl CH3 O-acyl Cl O 8-Fluorohypoxanthine Cl O-acyl CH3 0-acyl Cl 0 2, 8-Difluorohypoxanthine Cl O-acyl CH3 O-acyl Cl O 2-Aminoadenine Cl O-acyl CH3 O-acyl Cl O 2-Amino-8-fluoroadenine Cl O-acyl CH3 O-acyl Cl O 2-Amino-8-fluorohypoxanthine Cl O-acyl CH3 O-acyl Cl O 2-Aminohypoxanthine Cl O-acyl CH3 O-acyl Cl O 2-N-acetylguanine Cl O-acyl CH3 O-acyl Cl O 4-N-acetylcytosine Cl O-acyl CH3 O-acyl Cl O 6-N-acetyladenine Cl O-acyl CH3 O-acyl Cl O 2-N-acetyl-8-fluoroguanine Cl O-acyl CH3 O-acyl Cl O 4-N-acetyl-5-fluorocytosine Cl O-acyl CH3 O-acyl Cl O 6-N-acetyl-2-fluoroadenine Cl O-acyl CH3 O-acyl Cl O 6-N-acetyl-2, 8-difluoroadenine Cl O-acyl CH3 O-acy1 Cl O 6-N-acety1-2-aminoadenine Cl O-acyl CH3 O-acyl Cl O 6-N-acetyl-2-amino-8-fluoroadenine Cl O-acyl CH3 O-acyl Cl O 2-N-acetylaminoadenine Cl O-acyl CH3 O-acyl Cl O 2-N-acetylamino-8-fluoroadenine Cl O-acyl CH3 O-acyl Cl O 2-N-acetYlamino-8-fluorohypoxanthine Cl O-acyl CH3 O-acyl Cl O 2-N-acetylaminohypoxanthine Cl O-acyl CH3 O-acyl Cl O Thymine Cl OH CH3 O-acyl Cl O Uracil Cl OH CH3 O-acyl Cl O Guanine Cl OH CH3 O-acyl Cl O Cytosine Cl OH CH3 O-acyl Cl O Adenine Cl OH CH3 O-acyl Cl 0 Hypoxanthine Cl OH CH3 O-acyl Cl O 5-Fluorouracil Cl OH CH3 O-acyl C1 O 8-Fluoroguanine C1 OH CH3 O-acyl Cl O 5-Fluorocytosine Cl OH CH3 O-acyl Cl O 8-Fluoroadenine Cl OH CH3 O-acyl CI O 2-Fluoroadenine Cl OH CH3 O-acyl Cl O 2, 8-Difluoroadenine Cl OH CH3 O-acyl Cl O 2-Fluorohypoxanthine Cl OH CH3 O-acyl Cl O 8-Fluorohypoxanthine Cl OH R R R X Base Rl° le CH3 O-acyl Cl O 2, 8-Difluoroh oxanthine Cl OH YP CH3 O-acyl Cl O 2-Aminoadenine Cl OH CH3 O-acyl Cl O 2-Amino-8-fluoroadenine Cl OH CH3 O-acyl Cl O 2-Amino-8-fluorohypoxanthine Cl OH CH3 O-acyl Cl O 2-Aminohypoxanthine Cl OH CH3 O-acyl Cl O 2-N-acetylguanine Cl OH CH3 O-acyl Cl O 4-N-acetylcytosine Cl OH CH3 O-acyl Cl O 6-N-acetyladenine Cl OH CH3 O-acyl Cl O 2-N-acetyl-8-fluoroguanine Cl OH CH3 O-acyl CI O 4-N-acetyl-5-fluorocytosine Cl OH CH3 O-acyl Cl O 6-N-acetyl-2-fluoroadenine Cl OH CH3 O-acyl Cl O 6-N-acetyl-2, 8-difluoroadenine Cl OH CH3 O-acyl Cl O 6-N-acetyl-2-aminoadenine CI OH CH3 O-acyl Cl O 6-N-acetyl-2-amino-8-fluoroadenine Cl OH CH3 O-acyl Cl O 2-N-acetylaminoadenine Cl OH CH3 O-acyl Cl O 2-N-acetylamino-8-fluoroadenine Cl OH CH3 O-acyl Cl O 2-N-acetylamino-8-fluorohypoxanthine Cl OH CH3 O-acyl Cl O 2-N-acetylaminohypoxanthine Cl OH CH3 O-acyl Cl O Thymine H H CH3 O-acyl Cl O Uracil H H CH3 O-acyl Cl O Guanine H H CH3 O-acyl Cl O Cytosine H H CH3 O-acyl Cl O Adenine H H CH3 O-acyl Cl O Hypoxanthine H H CH3 O-acyl Cl O 5-Fluorouracil H H CH3 O-acyl Cl O 8-Fluoroguanine H H CH3 O-acyl Cl O 5-Fluorocytosine H H CH3 O-acyl Cl O 8-Fluoroadenine H H CH3 O-acyl Cl O 2-Fluoroadenine H H CH3 O-acyl Cl O 2, 8-Difluoroadenine H H CH3 O-ac 1 Cl O 2-Fluorohy oxanthine H H CH3 O-acyl Ci O 8-Fluorohypoxanthine H H CH3 0-acyl Cl 0 2, 8-Difluorohypoxanthine H H CH3 O-acyl Cl O 2-Aminoadenine H H CH3 O-acyl Cl O 2-Amino-8-fluoroadenine H H CH3 O-acyl Cl O 2-Amino-8-fluorohypoxanthine H H CH3 O-acyl Cl O 2-Aminohypoxanthine H H CH3 O-acyl Cl O 2-N-acetylguanine H H CH3 O-acyl Cl O 4-N-acetylcytosine H H CH3 O-ac 1 Cl O 6-N-acetyladenine H H CH3 0-acyl Cl 0 2-N-acetyl-8-fluoroguanine H H CH3 O-acyl Cl O 4-N-acetyl-5-fluorocytosine H H CH3 O-acyl Cl O 6-N-acetyl-2-fluoroadenine H H CH3 O-acyl Cl O 6-N-acetyl-2, 8-difluoroadenine H H CH3 O-acyl C1 O 6-N-acetyl-2-aminoadenine H H CH3 O-acyl Cl O 6-N-acetyl-2-amino-8-fluoroadenine H H CH3 O-acyl Cl O 2-N-acetylaminoadenine H H F R7 T X Base Rl° R9 CH3 0-acyl Cl 0 2-N-acetylamino-8-fluoroadenine H H CH3 O-acyl Cl O 2-N-acetylamino-8-fluorohypoxanthine H H CH3 O-acyl C1 O 2-N-acetylaminoh oxanthine H H CH3 O-acyl Cl O Thymine H O-amino acid CH3 0-acyl Cl 0 Uracil H 0-amino acid CH3 O-acyl Cl O Guanine H O-amino acid CH3 O-acyl Cl O Cytosine H O-amino acid CH3 O-acyl Cl O Adenine H O-amino acid CH3 O-acyl Cl O Hypoxanthine H O-amino acid CH3 O-acyl Cl O 5-Fluorouracil H O-amino acid CH3 O-acyl Cl O 8-Fluoroguanine H O-amino acid CH3 O-acyl Cl O 5-Fluorocytosine H O-amino acid CH3 O-acyl Cl O 8-Fluoroadenine H O-amino acid CH3 O-acyl Cl O 2-Fluoroadenine H O-amino acid CH3 O-acyl Cl O 2, 8-Difluoroadenine H 0-amino acid CH3 O-acyl Cl O 2-Fluorohypoxanthine H O-amino acid CH3 O-acyl Cl O 8-Fluorohypoxanthine H O-amino acid CH3 O-acyl Cl O 2, 8-Difluorohypoxanthine H O-amino acid CH3 O-acyl Cl O 2-Aminoadenine H O-amino acid CH3 O-acyl Cl O 2-Amino-8-fluoroadenine H O-amino acid CH3 O-acyl Cl O 2-Amino-8-fluorohypoxanthine H O-amino acid CH3 O-acyl Cl O 2-Aminohypoxanthine H O-amino acid CH3 O-acyl Cl O 2-N-acetylguanine H 0-amino acid CH3 O-acyl Cl O 4-N-acetylcytosine H O-amino acid CH3 O-acyl Cl O 6-N-acetyladenine H O-amino acid CH3 O-acyl Cl O 2-N-acetyl-8-fluoroguanine H O-amino acid CH3 O-acyl Cl O 4-N-acetyl-5-fluorocytosine H O-amino acid CH3 O-acyl Cl O 6-N-acetyl-2-fluoroadenine H O-amino acid CH3 O-acyl Cl O 6-N-acetyl-2, 8-difluoroadenine H O-amino acid CH3 O-acyl Cl O 6-N-acetyl-2-aminoadenine H O-amino acid CH3 O-acyl Cl O 6-N-acetyl-2-amino-8-fluoroadenine H 0-amino acid CH3 O-acyl Cl O 2-N-acetylaminoadenine H O-amino acid CH3 O-acyl Cl O 2-N-acetylamino-8-fluoroadenine H O-amino acid CH3 O-acyl Cl O 2-N-acetylamino-8-fluorohypoxanthine H O-amino acid CH3 O-acyl Cl O 2-N-acetylaminohypoxanthine H O-amino acid CH3 O-acyl Cl O Thymine H O-acyl CH3 O-acyl C1 O Uracil H O-acyl CH3 O-acyl Cl O Guanine H O-acyl CH3 O-acyl C 10 O Cytosine H O-acyl CH3 O-acyl Cl O Adenine H 0 O-acyl CH3 O-acyl Cl O Hypoxanthine H O-acyl CH3 O-acyl Cl O 5-Fluorouracil H O-acyl CH3 O-acyl Cl O 8-Fluoroguanine H O-acyl CH3 O-acyl Cl O 5-Fluorocytosine H O-acyl CH3 O-acyl Cl O 8-Fluoroadenine H O-acyl CH3 O-acyl Cl O 2-Fluoroadenine H O-acyl CH3 0-acyl ci 0 2, 8-Difluoroadenine H O-acyl R R R X Base R R CH3 0-acyl Cl 0 2-Fluorohypoxanthine H O-acyl CH3 O-acyl Cl O 8-Fluorohypoxanthine H O-acyl CH3 O-acyl Cl O 2, 8-Difluorohypoxanthine H 0-acyl CH3 O-acyl Cl O 2-Aminoadenine H O-acyl CH3 0-acyl Cl 0 2-Amino-8-fluoroadenine H 0-acyl CH3 O-acyl Cl O 2-Amino-8-fluorohypoxanthine H O-acyl CH3 O-acyl Cl O 2-Aminohypoxanthine H O-acyl CH3 O-acyl Cl O 2-N-acetylguanine H O-acyl CH3 O-acyl Cl O 4-N-acetylcytosine H O-acyl CH3 O-acyl Cl O 6-N-acetyladenine H O-acyl CH3 0-acyl Cl 0 2-N-acetyl-8-fluoroguanine H 0-acyl CH3 O-acyl Cl O 4-N-acetyl-5-fluorocytosine H O-acyl CH3 O-acyl Cl O 6-N-acetyl-2-fluoroadenine H O-acyl CH3 O-acyl Cl O 6-N-acetyl-2, 8-difluoroadenine H O-acyl CH3 O-acyl Cl O 6-N-acetyl-2-aminoadenine H O-acyl CH3 O-acyl Cl O 6-N-acetyl-2-amino-8-fluoroadenine H O-acyl CH3 O-acyl Cl O 2-N-acetylaminoadenine H O-acyl CH3 O-acyl Cl O 2-N-acetylamino-8-fluoroadenine H O-acyl CH3 O-acyl Cl O 2-N-acetylamino-8-fluorohypoxanthine H O-acyl CH3 0-acyl Cl 0 2-N-acetylaminohypoxanthine H 0-acyl CH3 O-acyl C1 O Thymine H OH CH3 O-acyl Cl O Uracil H OH CH3 O-acyl Cl O Guanine H OH CH3 O-acyl Cl O Cytosine H OH CH3 O-acyl C1 O Adenine H OH CH3 O-acyl Cl O Hypoxanthine H OH CH3 O-acyl Cl O 5-Fluorouracil H OH CH3 O-acyl Cl O 8-Fluoroguanine H OH CH3 O-acyl Cl O 5-Fluorocytosine H OH CH3 O-acyl Cl O 8-Fluoroadenine H OH CH3 O-acyl Cl O 2-Fluoroadenine H OH CH3 0-acyl Cl 0 2, 8-Difluoroadenine H OH CH3 O-ac 1 Cl O 2-Fluorohy oxanthine H OH CH3 O-acyl Cl O 8-Fluorohypoxanthine H OH CH3 O-acyl Cl O 2, 8-Difluorohypoxanthine H OH CH3 O-acyl Cl O 2-Aminoadenine H OH CH3 O-acyl Cl O 2-Amino-8-fluoroadenine H OH CH3 0-acyl Cl 0 2-Amino-8-fluorohypoxanthine H OH CH3 O-ac 1 Cl O 2-Aminoh oxanthine H OH CH3 0-acyl Cl 0 2-N-acetyl guanine H OH CH3 O-acyl Cl O 4-N-acetylcytosine H OH CH3 O-acyl Cl O 6-N-acetyladenine H OH CH3 O-acyl Cl O 2-N-acetyl-8-fluoroguanine H OH CH3 O-acyl Cl O 4-N-acetyl-5-fluorocytosine H OH CH3 0-acyl Cl 0 6-N-acetyl-2-fluoroadenine H OH CH3 O-acyl Cl O 6-N-acetyl-2, 8-difluoroadenine H OH CH3 O-acyl Cl O 6-N-acetyl-2-aminoadenine H OH R6 R7 R8 X Base R R CH3 O-acyl Cl O 6-N-acetyl-2-amino-8-fluoroadenine H OH CH3 O-acyl Cl O 2-N-acetylaminoadenine H OH CH3 O-acyl Cl O 2-N-acetylamino-8-fluoroadenine H OH CH3 O-acyl Cl O 2-N-acetylamino-8-fluorohypoxanthine H OH CH3 O-acyl Cl O 2-N-acetylaminohypoxanthine H OH CH3 O-acyl Cl O Thymine OH H CH3 O-acyl Cl O Uracil OH H CH3 O-acyl Cl Cl O Guanine OH H CH3 O-acyl Cl O Cytosine OH H CH3 O-acyl Cl O Adenine OH H CH3 O-acyl Cl O Hypoxanthine OH H CH3 O-acyl Cl O 5-Fluorouracil OH H CH3 O-acyl Cl O 8-Fluoroguanine OH H CH3 O-acyl Cl O 5-Fluorocytosine OH H CH3 O-acyl Cl O 8-Fluoroadenine OH H CH3 O-acyl Cl O 2-Fluoroadenine OH H CH3 O-acyl Cl O 2, 8-Difluoroadenine OH H CH3 0-acyl Cl O 2-Fluorohypoxanthine OH H CH3 O-acyl Cl O 8-Fluorohypoxanthine OH H CH3 O-acyl Cl O 2, 8-Difluorohypoxanthine OH H CH3 O-acyl Cl O 2-Aminoadenine OH H CH3 0-acyl Cl 0 2-Amino-8-fluoroadenine OH H CH3 O-acyl Cl O 2-Amino-8-fluorohypoxanthine OH H CH3 0-acyl Cl 0 2-Aminohypoxanthine OH H CH3 0-acyl Cl 0 2-N-acetyl guanine OH H CH3 O-acyl Cl O 4-N-acetylcytosine OH H CH3 O-acyl Cl O 6-N-acetyladenine OH H CH3 O-acyl Cl O 2-N-acetyl-8-fluoroguanine OH H CH3 O-acyl Cl O 4-N-acetyl-5-fluorocytosine OH H CH3 O-acyl Cl O 6-N-acetyl-2-fluoroadenine OH H CH3 O-acyl Cl O 6-N-acetyl-2, 8-difluoroadenine OH H CH3 O-acyl Cl O 6-N-acetyl-2-aminoadenine OH H CH3 O-acyl Cl O 6-N-acety1-2-amino-8-fluoroadenine OH H CH3 O-acyl Cl O 2-N-acetylaminoadenine OH H CH3 O-acyl Cl O 2-N-acetylamino-8-fluoroadenine OH H CH3 O-acyl Cl O 2-N-acetylamino-8-fluorohypoxanthine OH H CH3 O-acyl Cl O 2-N-acetylaminohypoxanthine OH H CH3 O-acyl H O Thymine F H CH3 O-acyl H O Uracil F H CH3 0-acy ! H0 GuanineFH CH3 O-acyl H O Cytosine F H CH3 O-acyl H O Adenine F H CH3 O-acyl H O Hypoxanthine F H CH3 O-acyl H O 5-Fluorouracil F H CH3 O-acyl H O 8-Fluoroguanine F H CH3 O-acyl H O 5-Fluorocytosine F H CH3 O-acyl H O 8-Fluoroadenine F H R'R'R8 X I Base R'° le CH3 O-acyl H O 2-Fluoroadenine F H CH3 O-acyl H O 2, 8-Difluoroadenine F H CH3 O-acyl H O 2-Fluorohypoxanthine F H CH3 O-acyl H O 8-Fluorohypoxanthine F H CH3 O-acyl H O 2, 8-Difluorohypoxanthine F H CH3 O-acyl H O 2-Aminoadenine F H CH3 O-ac 1 H O 2-Amino-8-fluoroadenine F H CH3 O-acyl H O 2-Amino-8-fluorohypoxanthine F H CH3 O-acyl H O 2-Aminohypoxanthine F H CH3 O-acyl H O 2-N-acetylguanine F H CH3 O-acyl H O 4-N-acet lc osine F H CH3 0-acyl H 0 6-N-acetyladenine F H CH3 O-acyl H O 2-N-acetyl-8-fluoroguanine F H CH3 O-acyl H O 4-N-acetyl-5-fluorocytosine F H CH3 0-acyl H 0 6-N-acetyl-2-fluoroadenine F H CH3 O-acyl H O 6-N-acetyl-2, 8-difluoroadenine F H CH3 O-acyl H O 6-N-acetyl-2-aminoadenine F H CH3 O-acyl H O 6-N-acetyl-2-amino-8-fluoroadenine F H CH3 0-acyl H 0 2-N-acetylaminoadenine F H CH3 O-acyl H O 2-N-acetylamino-8-fluoroadenine F H CH3 O-acyl H O 2-N-acetylamino-8-fluorohypoxanthine F H CH3 O-acyl H O 2-N-acetylaminohypoxanthine F H CH3 O-acyl H O Thymine F O-amino acid CH3 O-acyl H O Uracil F O-amino acid CH3 0-acyl H O Guanine F O-amino acid CH3 O-acyl H O Cytosine F O-amino acid CH3 O-acyl H O Adenine F O-amino acid CH3 O-acyl H O Hypoxanthine F O-amino acid CH3 O-acyl H O 5-Fluorouracil F O-amino acid CH3 O-acyl H O 8-Fluoroguanine F O-amino acid CH3 O-acyl H O 5-Fluorocytosine F O-amino acid CH3 O-acyl H O 8-Fluoroadenine F O-amino acid CH3 O-acyl H O 2-Fluoroadenine F O-amino acid CH3 O-acyl H O 2, 8-Difluoroadenine F O-amino acid CH3 O-acyl H O 2-Fluorohypoxanthine F O-amino acid CH3 O-acyl H O 8-Fluorohypoxanthine F O-amino acid CH3 O-acyl H O 2, 8-Difluorohypoxanthine F O-amino acid CH3 O-acyl H O 2-Aminoadenine F O-amino acid CH3 O-acyl H O 2-Amino-8-fluoroadenine F O-amino acid CH3 O-acyl H O 2-Amino-8-fluorohypoxanthine F O-amino acid CH3 O-acyl H O 2-Aminohypoxanthine F 0-amino acid CH3 O-acyl H O 2-N-acetylguanine F O-amino acid CH3 O-acyl H O 4-N-acetylcytosine F O-amino acid CH3 O-acyl H O 6-N-acetyladenine F 0-amino acid CH3 O-acyl H O 2-N-acetyl-8-fluoroguanine F O-amino acid CH3 O-acyl H O 4-N-acetyl-5-fluorocytosine F O-amino acid CH3 O-acyl H O 6-N-acetyl-2-fluoroadenine F O-amino acid R6 R7 R8 X Base R R CH3 O-acyl H O 6-N-acetyl-2, 8-difluoroadenine F O-amino acid CH3 O-acyl H O 6-N-acetyl-2-aminoadenine F 0-amino acid CH3 O-acyl H O 6-N-acetyl-2-amino-8-fluoroadenine F O-amino acid CH3 O-acyl H O 2-N-acetylaminoadenine F O-amino acid CH3 O-acyl H O 2-N-acetylamino-8-fluoroadenine F O-amino acid CH3 O-acyl H O 2-N-acetylamino-8-fluorohypoxanthine F O-amino acid CH3 O-acyl H O 2-N-acetylaminohypoxanthine F O-amino acid CH3 O-acyl H O Thymine F 0-acyl CH3 O-acyl H O Uracil F O-acyl CH3 O-acyl H O Guanine F O-acyl CH3 O-acyl H O Cytosine F O-acyl CH3 O-acyl H O Adenine F O-acyl CH3 O-acyl 1 10 Hypoxanthine F 0-acyl CH3 O-acyl H O 5-Fluorouracil F 0-acyl CH3 O-acyl H O 8-Fluoroguanine F O-acyl CH3 O-acyl H O 5-Fluorocytosine F O-acyl CH3 O-acyl H O 8-Fluoroadenine F O-acyl CH3 O-acyl H O 2-Fluoroadenine F O-acyl CH3 O-acyl H O 2, 8-Difluoroadenine F O-acyl CH3 O-acyl H O 2-Fluorohy oxanthine F O-acyl CH3 0-acyl H 0 8-Fluorohypoxanthine F 0-acyl CH3 O-acyl H O 2, 8-Difluorohypoxanthine F O-acyl CH3 O-acyl H O 2-Aminoadenine F O-acyl CH3 O-acyl H O 2-Amino-8-fluoroadenine F O-acyl CH3 0-acy) H O 2-Amino-8-fluorohypoxanthine F O-acyI CH3 O-acyl H O 2-Aminohypoxanthine F O-acyl CH3 O-acyl H O 2-N-acetylguanine'F O-acyl CH3 0-acyl H O 4-N-acetylcytosine F O-acyl CH3 O-acyl H 0 6-N-acetyladenine F 0-acyl CH3 O-acyl H O 2-N-acetyl-8-fluoroguanine F O-acyl CH3 O-acyl H O 4-N-acetyl-5-fluorocytosine F O-acyl CH3 O-acyl H O 6-N-acetyl-2-fluoroadenine F O-acyl CH3 0-acyl H 0 6-N-acetyl-2, 8-difluoroadenine F 0-acyl CH3 O-acyl H O 6-N-acetyl-2-aminoadenine F O-ac 1 CH3 O-acyl H O 6-N-acetyl-2-amino-8-fluoroadenine F O-acyl CH3 O-acyl H O 2-N-acetylaminoadenine F O-acyl CH3 O-acyl H O 2-N-acetylamino-8-fluoroadenine F O-acyl CH3 O-acyl H O 2-N-acetylamino-8-fluorohypoxanthine F O-acyl CH3 O-acyl H O 2-N-acetylaminohypoxanthine F O-acyl CH3 O-acyl H O Thymine F OH CH3 O-acyl H O Uracil F OH CH3 0-acyl H O Guanine F OH CH3 O-acyl H O Cytosine F OH CH3 0-acy ! H0 AdenineJFOH CH3 O-acyl 1 0 Hypoxanthine F OH CH3 O-acyl H O 5-Fluorouracil F OH CH3 O-ac 1 H O 8-Fluoro uanine F OH R6 R R X Base R R CH3 0-acyl H O 5-Fluorocytosine F OH CH3 O-acyl H O 8-Fluoroadenine F OH CH3 O-acyl H O 2-Fluoroadenine F OH CH3 O-acyl H O 2, 8-Difluoroadenine F OH CH3 O-ac 1 H O 2-Fluoroh oxanthine F OH CH3 O-acyl H O 8-Fluorohypoxanthine F OH CH3 0-acy ! H0 2, 8-Difluorohypoxanthine F OH CH3 0-acyl H 0 2-Aminoadenine F OH CH3 O-acyl H O 2-Amino-8-fluoroadenine F OH CH3 O-acyl H O 2-Amino-8-fluorohypoxanthine F OH CH3 O-acyl H O 2-Aminohypoxanthine F OH CH3 O-acyl H O 2-N-acetylguanine F OH CH3 O-acyl H O 4-N-acetylcytosine F OH CH3 0-acyl H O 6-N-acetyladenine F OH CH3 O-acyl H O 2-N-acetyl-8-fluoroguanine F OH CH3 O-acyl H O 4-N-acetyl-5-fluorocytosine F OH CH3 O-acyl H O 6-N-acetyl-2-fluoroadenine F OH CH3 O-acyl H O 6-N-acetyl-2, 8-difluoroadenine F OH CH3 O-acyl H O 6-N-acetyl-2-aminoadenine F OH CH3 O-acyl H O 6-N-acetyl-2-amino-8-fluoroadenine F OH CH3 O-acYI H O 0 2-N-acetylaminoadenine F OH CH3 O-acyl H O 2-N-acetylamino-8-fluoroadenine F OH CH3 O-acyl H O 2-N-acetylamino-8-fluorohypoxanthine F OH CH3 O-acyl H O 2-N-acetylaminohypoxanthine F OH CH3 O-acyl H O Thymine Br H CH3 O-acyl H O Uracil Br H CH3 O-acyl H O Guanine Br H CH3 O-acyl 1 0 Cytosine Br H CH3 O-acyl H O Adenine Br H CH3 0-acyl H 0 Hypoxanthine Br H CH3 O-ac 1 H O 5-Fluorouracil Br H CH3 O-acyl H O 8-Fluoroguanine Br H CH3 O-ac 1 H O 5-Fluorocytosine Br H CH3 O-acyl H O 8-Fluoroadenine Br H CH3 O-acyl H O 2-Fluoroadenine Br H CH3 O-acyl H O 2, 8-Difluoroadenine Br H CH3 O-acyl H O 2-Fluorohypoxanthine Br H CH3 O-acyl H O 8-Fluorohypoxanthine Br H CH3 O-acyl H O 2, 8-Difluorohypoxanthine Br H CH3 O-acyl H O 2-Aminoadenine Br H CH3 O-acyl H O 2-Amino-8-fluoroadenine Br H CH3 O-acyl H O 2-Amino-8-fluorohypoxanthine Br H CH3 O-acyl XHX O 2-Aminohypoxanthine Br H CH3 O-acyl H O 2-N-acetylguanine Br H CH3 0-acyl H 0 4-N-acetylcytosine Br H CH3 O-acyl H O 6-N-acetyladenine Br H CH3 O-acyl H O 2-N-acetyl-8-fluoroguanine Br H R R R X Base R R CH3 O-acyl H O 4-N-acetyl-5-fluorocytosine Br H CH3 O-acyl H O 6-N-acetyl-2-fluoroadenine Br H CH3 O-acyl H O 6-N-acetyl-2, 8-difluoroadenine Br H CH3 O-acyl H O 6-N-acetyl-2-aminoadenine Br H CH3 O-acyl H O 6-N-acetyl-2-amino-8-fluoroadenine Br H CH3 O-acyl H O 2-N-acetylaminoadenine Br H CH3 O-acyl H O 2-N-acetylamino-8-fluoroadenine Br H CH3 0-acyl H O 2-N-acetylamino-8-fluorohypoxanthine Br H CH3 O-acyl H O 2-N-acetylaminohypoxanthine Br H CH3 O-acyl H O Thymine Br O-amino acid CH3 O-acyl H O Uracil Br O-amino acid CH3 0-acyl H 0 Guanine Br 0-amino acid CH3 O-acyl H O Cytosine Br O-amino acid CH3 O-acyl H O Adenine Br O-amino acid CH3 O-acyl H O Hypoxanthine Br O-amino acid CH3 O-ac 1 H O 5-Fluorouracil Br O-amino acid CH3 O-acyl H O 8-Fluoroguanine Br O-amino acid CH3 O-ac 1 H O 5-Fluorocytosine Br O-amino acid CH3 O-acyl H O 8-Fluoroadenine Br O-amino acid CH3 O-acyl H O 2-Fluoroadenine Br O-amino acid CH3 O-acyl H O 2, 8-Difluoroadenine Br O-amino acid CH3 O-acyl H O 2-Fluorohypoxanthine Br O-amino acid CH3 O-acyl H O 8-Fluorohypoxanthine Br O-amino acid CH3 O-acyl H O 2, 8-Difluorohypoxanthine Br O-amino acid CH3 O-acyl H O 2-Aminoadenine Br O-amino acid CH3 O-acyl H O 2-Amino-8-fluoroadenine Br O-amino acid CH3 O-acyl H O 2-Amino-8-fluorohypoxanthine Br O-amino acid CH3 O-acyl H O 2-Aminohypoxanthine Br 0-amino acid CH3 O-acyl H O 2-N-acetylguanine Br O-amino acid CH3 0-acyl H 0 4-N-acetylcytosine Br 0-amino acid CH3 O-acyl H O 6-N-acetyladenine Br O-amino acid CH3 O-acyl H O 2-N-acetyl-8-fluoroguanine Br O-amino acid CH3 O-acyl H O 4-N-acetyl-5-fluorocytosine Br O-amino acid CH3 O-acyl H O 6-N-acetyl-2-fluoroadenine Br O-amino acid CH3 O-acyl H O 6-N-acetyl-2, 8-difluoroadenine Br O-amino acid CH3 O-acyl H O 6-N-acetyl-2-aminoadenine Br O-amino acid CH3 O-acyl H O 6-N-acetyl-2-amino-8-fluoroadenine Br O-amino acid CH3 O-acyl H O 2-N-acetylaminoadenine Br O-amino acid CH3 O-acyl H O 2-N-acetylamino-8-fluoroadenine Br O-amino acid CH3 O-acyl H O 2-N-acetylamino-8-fluorohypoxanthine Br O-amino acid CH3 O-acyl H O 2-N-acetylaminohypoxanthine Br O-amino acid CH3 O-acyl H O Thymine Br O-acyl CH3 O-acyl H O Uracil Br O-acyl CH3 O-acyl H O Guanine Br O-acyl CH3 O-acyl 1 O Cytosine Br O-acyl CH3 O-acyl H O Adenine Br O-acyl CH3 O-acyl H O Hypoxanthine Br O-acyl R R R X Base R"R CH3 O-acyl H O 5-Fluorouracil Br O-acyl CH3 O-acyl H O 8-Fluoroguanine Br O-acyl CH3 O-acyl H O 5-Fluorocytosine Br O-acyl CH3 O-acyl H O 8-Fluoroadenine Br O-acyl CH3 O-acyl H O 2-Fluoroadenine Br O-acyl CH3 O-acyl H O 2, 8-Difluoroadenine Br O-acyl CH3 O-acyl H O 2-Fluorohypoxanthine Br O-acyl CH3 O-acyl H O 8-Fluorohypoxanthine Br O-acyl CH3 O-acyl H O 2, 8-Difluoroh oxanthine Br O-ac 1 CH3 O-acyl H O 2-Aminoadenine Br O-acyl CH3 O-acyl H O 2-Amino-8-fluoroadenine Br O-acyl CH3 O-acyl H O 2-Amino-8-fluorohypoxanthine Br O-acyl CH3 O-acyl H O 2-Aminohypoxanthine Br O-acyl CH3 O-acyl H O 2-N-acetylguanine Br O-acyl CH3 O-acyl H O 4-N-acetylcytosine Br O-acyl CH3 O-acyl H O 6-N-acetyladenine Br O-acyl CH3 O-acyl H O 2-N-acetyl-8-fluoroguanine Br O-acyl CH3 O-acyl H O 4-N-acetyl-5-fluorocytosine Br O-acyl CH3 O-acyl H O 6-N-acetyl-2-fluoroadenine Br O-acYI CH3 O-acyl H O 6-N-acetyl-2, 8-difluoroadenine Br O-acyl CH3 O-acyl H O 6-N-acetyl-2-aminoadenine Br O-acyl CH3 O-acyl H O 6-N-acetyl-2-amino-8-fluoroadenine Br O-acyl CH3 0-acyl H 0 2-N-acetylaminoadenine Br 0-acyl CH3 O-acyl H O 2-N-acetylamino-8-fluoroadenine Br O-acyl CH3 O-acyl H O 2-N-acetylamino-8-fluorohypoxanthine Br O-acyl CH3 O-acyl H O 2-N-acetylaminohypoxanthine Br O-acyl CH3 O-acyl H O Thymine Br OH CH3 O-acyl H O Uracil Br OH CH3 O-acyl H O Guanine Br OH CH3 O-acyl H O Cytosine Br OH CH3 O-acyl H O Adenine Br OH CH3 O-acyl H 0 Hypoxanthine Br OH CH3 O-ac 1 H O 5-Fluorouracil Br OH CH3 O-acyl H Q 8-Fluoroguanine Br OH CH3 O-acyl H O 5-Fluorocytosine Br OH CH3 O-acyl H O 8-Fluoroadenine Br OH CH3 O-acyl H O 2-Fluoroadenine Br OH CH3 O-acyl H O 2, 8-Difluoroadenine Br OH CH3 O-acyl H O 2-Fluoroh oxanthine Br OH CH3 O-acyl H O 8-Fluorohypoxanthine Br OH CH3 O-acyl H O 2, 8-Difluorohypoxanthine Br OH CH3 O-acyl H O 2-Aminoadenine Br OH CH3 O-acyl H O 2-Amino-8-fluoroadenine Br OH CH3 O-acyl H 0 2-Amino-8-fluorohypoxanthine Br OH CH3 0-acyl H 0 2-Aminohypoxanthine Br OH CH3 O-acyl H O 2-N-acetyIguanine Br OH CH3 O-acyl H Q 4-N-acetylcytosine Br OH R R R X Base R R CH3 O-acyl H Q 6-N-acetyladenine Br OH CH3 O-acyl H Q 2-N-acetyl-8-fluoroguanine Br OH CH3 O-acyl H 0 4-N-acetyl-5-fluorocytosine Br OH CH3 O-acyl H Q 6-N-acetyl-2-fluoroadenine Br OH CH3 O-acyl H Q 6-N-acetyl-2, 8-difluoroadenine Br OH CH3 O-acg H O 6-N-acetyl-2-am inoadenine Br OH CH3 O-acyl H O 6-N-acetyl-2-amino-8-fluoroadenine Br OH CH3 O-acyl H O 2-N-acetylaminoadenine Br OH CH3 O-acyl H O 2-N-acetylamino-8-fluoroadenine Br OH CH3 0-acyl H O 2-N-acetylamino-8-fluorohypoxanthine Br OH CH3 O-acyl H 0 2-N-acetylaminohypoxanthine Br OH CH3 O-acyl H O Thymine Cl H CH3 O-acyl H O Uracil Cl H CH3 0-acyl H 0 Guanine Cl H CH3 O-acyl H O Cytosine Cl H CH3 O-acyl H O Adenine Cl H CH3 O-acyl H O Hypoxanthine Cl H CH3 O-acyl H O 5-Fluorouracil Cl H CH3 O-acyl H O 8-Fluoroguanine Cl H CH3 O-acyl H O 5-Fluorocytosine Cl H CH3 0-acyl H O 8-Fluoroadenine Cl H CH3 O-acyl H O 2-F luoroadenine C I H CH3 O-acyl H O 2, 8-Difluoroadenine Cl H CH3 0-acyl H 0 2-Fluorohypoxanthine Cl H CH3 O-acyl H O 8-Fluorohypoxanthine Cl H CH3 O-acyl H O 2, 8-Difluorohypoxanthine Cl H CH3 O-ac 1 H O 2-Aminoadenine Cl H CH3 O-acyl H O 2-Amino-8-fluoroadenine Cl H CH3 O-acyl H O 2-Amino-8-fluorohypoxanthine Cl H CH3 O-acyl H O 2-Aminohypoxanthine Cl H CH3 O-acyl H O 2-N-acetyl guanine C I H CH3 O-acyl H O 4-N-acetylcytosine Cl H CH3 O-acyl H O 6-N-acetyladenine Cl H CH3 O-acyl H O 2-N-acetyl-8-fluoroguanine Cl H CH3 O-acyl H O 4-N-acetyl-5-fluorocytosine Cl H CH3 O-acyl H O 6-N-acetyl-2-fluoroadenine Cl H CH3 O-acyl H O 6-N-acetyl-2, 8-difluoroadenine Cl H CH3 O-acyl H O 6-N-acetyl-2-aminoadenine Ct H CH3 O-acyl H O 6-N-acetyl-2-am ino-8-fluoroadenine C I H CH3 O-acyl H O 2-N-acetylaminoadenine Cl H CH3 O-acyl H O 2-N-acetylamino-8-fluoroadenine Cl H CH3 O-acyl H O 2-N-acetylamino-8-fluorohypoxanthine Cl H CH3 O-acyl H O 2-N-acetylaminohypoxanthine Cl H CH3 O-acyl H O Thymine Cl 0-amino acid CH3 O-acyl H O Uracil Cl O-amino acid CH3 0-acyl H O Guanine Cl O-amino acid CH3 O-acyl H 0 Cytosine Cl O-amino acid R6 R7 R8 X Base Rl° R9 CH3 O-acyl H O Adenine Cl O-amino acid CH3 O-acyl H O Hypoxanthine Cl O-amino acid CH3 O-acyl H O 5-Fluorouracil C ! 0-amino acid CH3 O-acyl H O 8-Fluoroguanine Cl O-amino acid CH3 O-acyl H O 5-Fluorocytosine Cl O-amino acid CH3 O-acyl H 0 8-Fluoroadenine Cl O-amino acid CH3 O-acyl H O 2-Fluoroadenine Cl O-amino acid CH3 O-acyl H 0 2, 8-Difluoroadenine Cl 0-amino acid CH3 O-ac 1 H O 2-Fluorohy oxanthine C1 O-amino acid CH3 O-acyl H O 8-Fluorohypoxanthine Cl O-amino acid CH3 0-acy ! H0 2, 8-Difluorohypoxanthine Cl O-amino acid CH3 O-acyl H 0 2-Aminoadenine Cl 0-amino acid CH3 O-acyl H O 2-Amino-8-fluoroadenine Cl O-amino acid CH3 O-acyl H O 2-Amino-8-fluorohypoxanthine Cl O-amino acid CH3 O-acyl H 0 2-Aminohypoxanthine Cl O-amino acid CH3 O-acyl H O 2-N-acetylguanine Cl O-amino acid CH3 O-acyl H O 4-N-acetylcytosine Cl O-amino acid CH3 O-acyl H 0 6-N-acetyladenine Cl O-amino acid CH3 O-acyl H O 2-N-acetyl-8-fluoroguanine Cl O-amino acid CH3 O-acyl H O 4-N-acetyl-5-fluorocytosine Cl O-amino acid CH3 O-acyl H O 6-N-acetyl-2-fluoroadenine Cl O-amino acid CH3 O-acyl H O 6-N-acetyl-2, 8-difluoroadenine Cl O-amino acid CH3 O-acyl H O 6-N-acetyl-2-aminoadenine Cl O-amino acid CH3 O-acyl H O 6-N-acetyl-2-amino-8-fluoroadenine Cl O-amino acid CH3 O-acyl H O 2-N-acetylaminoadenine Cl O-amino acid CH3 O-acyl H O 2-N-acetylamino-8-fluoroadenine Cl O-amino acid CH3 O-acyl H O 2-N-acetylamino-8-fluorohypoxanthine Cl O-amino acid CH3 O-acyl H O 2-N-acetylaminohypoxanthine Cl O-amino acid CH3 O-acyl H 0 Thymine Cl 0-acyl CH3 O-acyl H 0 Uracil Cl O-acyl CH3 O-acyl H 0 Guanine Cl O-acyl CH3 O-acyl H 0 Cytosine Cl O-acyl CH3 O-acyl H 0 Adenine Cl O-acyl CH3 O-acyl H 0 Hypoxanthine Cl O-acyl CH3 O-acyl H 0 5-Fluorouracil Cl O-acyl CH3 O-acyl H O 8-Fluoroguanine Cl O-acyl CH3 O-acyl H 0 5-Fluorocytosine Cl O-acyl CH3 O-acyl H O 8-Fluoroadenine Cl O-acyl CH3 O-acyl H O 2-Fluoroadenine Cl O-acyl CH3 O-acyl H O 2, 8-Difluoroadenine Cl O-acyl CH3 0-acyl H 0 2-Fluorohypoxanthine Cl 0-acyl CH3 O-acyl H O 8-Fluorohypoxanthine C1 O-ac 1 CH3 O-acyl H O 2, 8-Difluorohy oxanthine C1 O-ac 1 CH3 O-acyl H O 2-Am i noaden ine C I O-acyl CH3 0-acyl H O 2-Amino-8-fluoroadenine Cl O-acyl CH3 O-acyl H O 2-Amino-8-fluorohypoxanthine Cl O-acyl CH3 O-acyl H O 2-Aminohypoxanthine Cl O-acyl R6 R7 T X Base Rl° R CH3 O-acyl H O 2-N-acetylguanine Cl O-acyl CH3 O-acyl H O 4-N-acetylcytosine Cl O-acyl CH3 O-acyl H O 6-N-acetyladenine Cl O-acyl CH3 O-acyl H O 2-N-acetyl-8-fluoroguanine Cl O-acyl CH3 O-acyl H O 4-N-acetyl-5-fluorocytosine Cl O-acyl CH3 0-acyl H 0 6-N-acetyl-2-fluoroadenine Cl 0-acyl CH3 O-acyl H O 6-N-acetyl-2, 8-difluoroadenine Cl O-acyl CH3 O-ac I H O 6-N-acet 1-2-aminoadenine Cl O-ac 1 CH3 O-acyl H 0 6-N-acetyl-2-amino-8-fluoroadenine Cl O-acyl CH3 O-acyl H O 2-N-acetylaminoadenine Cl O-acyl CH3 0-acyl H 0 2-N-acetylamino-8-fluoroadenine Cl 0-acyl CH3 O-acyl H O 2-N-acetylamino-8-fluorohypoxanthine Cl O-ac l CH3 O-acyl H O 2-N-acetylaminohypoxanthine Cl O-acyl CH3 O-acyl H O Thymine Cl OH CH3 O-acyl H O Uracil Cl OH CH3 0-acyl H 0 Guanine Cl OH CH3 O-acyl H O Cytosine Cl OH CH3 O-acyl H O Adenine Cl OH CH3 O-acyl H O Hypoxanthine C I OH CH3 O-acyl H O 5-Fluorouracil Cl OH CH3 O-acyl H O 8-Fluoroguanine Cl OH CH3 O-acyl H 0 5-Fluorocytosine Cl OH CH3 O-acyl H 0 8-Fluoroadenine Cl OH CH3 O-acyl H Q 2-Fluoroadenine Cl OH CH3 0-acyl0 2, 8-Difluoroadenine Cl OH CH3 O-ac 1 H O 2-Fluoroh oxanthine C1 OH CH3 O-acyl H O 8-Fluoroh oxanthine Cl OH CH3 0-acyl0 2, 8-Difluorohypoxanthine Cl OH CH3 O-ac 1 H O 2-Aminoadenine C1 OH CH3 O-acyl H O 2-Amino-8-fluoroadenine Cl OH CH3 O-ac 1 H O 2-Amino-8-fluoroh oxanthine Cl OH CH3 O-ac 1 H O 2-Aminoh oxanthine C1 OH CH3 0-acyl H 0 2-N-acetyl guanine Cl OH CH3 O-ac 1 H O 4-N-acetylcytosine Cl OH CH3 O-acyl H Q 6-N-acetyladenine C I OH CH3 O-acyl H O 2-N-acetyl-8-fluoroguanine Cl OH CH3 O-acyl H O 4-N-acetyl-5-fluoroc osine CI OH CH3 O-acyl H O 6-N-acet 1-2-fluoroadenine CI OH CH3 O-acyl H Q 6-N-acetyl-2, 8-difluoroadenine Cl OH CH3 O-acyl H O 6-N-acet 1-2-aminoadenine CI OH CH3 O-acyl H O 6-N-acetyl-2-amino-8-fluoroadenine CI OH CH3 O-acyl H 0 2-N-acetylaminoadenine Cl OH CH3 O-acyl H O 2-N-acetylamino-8-fluoroadenine Cl OH CH3 O-acyl H O 2-N-acetylamino-8-fluorohypoxanthine Cl OH CH3 O-acyl H O 2-N-acetylaminohypoxanthine Cl OH CH3 O-acyl H O Thymine H H CH3 O-acyl H O Uracil H H R7 R8 X I Base R R CH3 O-acyl H O Guanine H H CH3 O-acyl H O Cytosine H H CH3 O-acyl H O Adenine H H CH3 O-acyl H O Hypoxanthine H H CH3 O-ac 1 H O 5-Fluorouracil H H CH3 O-ac 1 H O 8-Fluoro uanine H H CH3 O-acyl H 0 5-Fluorocytosine H H CH3 O-acyl H O 8-Fluoroadenine H H CH3 O-acyl H O 2-Fluoroadenine H H CH3 O-acyl H O 2, 8-Difluoroadenine H H CH3 O-acyl H O 2-Fluorohypoxanthine H H CH3 O-acyl H O 8-Fluorohypoxanthine H H CH3 O-acyl H O 2, 8-Difluorohypoxanthine H H CH3 O-acyl H 0 2-Aminoadenine H H CH3 O-ac I H O 2-Amino-8-fluoroadenine H H CH3 0-acyl H 0 2-Amino-8-fluorohypoxanthine H H CH3 O-acyl H O 2-Aminohypoxanthine H H CH3 O-acyl H O 2-N-acetylguanine H H CH3 O-acyl H O 4-N-acetylcytosine H H CH3 O-acyl H O 6-N-acetyladenine H H CH3 O-acyl H O 2-N-acetyl-8-fluoroguanine H H CH3 O-acyl H O 4-N-acetyl-5-fluorocytosine H H CH3 O-acyl H 0 6-N-acetyl-2-fluoroadenine H H CH3 O-acyl H Q 6-N-acetyl-2, 8-difluoroadenine H H CH3 O-acyl H O 6-N-acetyl-2-aminoadenine H H CH3 O-acyl H O 6-N-acetyl-2-amino-8-fluoroadenine H H CH3 O-acyl H O 2-N-acetylaminoadenine H H CH3 O-acyl H O 2-N-acetylamino-8-fluoroadenine H H CH3 O-acyl H 0 2-N-acetylamino-8-fluorohypoxanthine H H CH3 O-acyl H O 2-N-acetylaminohypoxanthine H H CH3 O-acyl H O Thymine H O-amino acid CH3 0-acyl H 0 Uracil H 0-amino acid CH3 0-acyl H 0 Guanine H 0-amino acid CH3 O-acyl H O Cytosine H O-amino acid CH3 O-acyl H O Adenine H O-amino acid CH3 O-acyl H O Hypoxanthine H O-amino acid CH3 O-acyl H O 5-Fluorouracil H O-amino acid CH3 O-acyl H O 8-Fluoroguanine H O-amino acid CH3 O-acyl H O 5-Fluorocytosine H O-amino acid CH3 0-acyl H 0 8-Fluoroadenine H 0-amino acid CH3 O-acyl H Q 2-Fluoroadenine H O-amino acid CH3 O-acyl H O 2, 8-Difluoroadenine H O-amino acid CH3 O-acyl H O 2-Fluorohypoxanthine H 0-amino acid CH3 O-acyl H 0 8-Fluorohypoxanthine H O-amino acid CH3 0-acy ! 0 2, 8-Difluorohypoxanthine H O-amino acid CH3 O-acyl H O 2-Aminoadenine H O-amino acid CH3 O-acyl H Q 2-Amino-8-fluoroadenine H O-amino acid R6 R 7 R8 X Base Rl° R9 CH3 O-acyl H O 2-Amino-8-fluorohypoxanthine H O-amino acid CH3 O-acyl H O 2-Aminohypoxanthine H 0-amino acid CH3 O-acyl H O 2-N-acetylguanine H O-amino acid CH3 O-acyl H O 4-N-acetylcytosine H 0-amino acid CH3 O-ac 1 H O 6-N-acetyladenine H O-amino acid CH3 0-acyl H 0 2-N-acetyl-8-fluoroguanine H 0-amino acid CH3 O-acyl H O 4-N-acetyl-5-fluorocytosine H O-amino acid CH3 0-acyl H 0 6-N-acetyl--fluoroadenine H 0-amino acid CH3 O-acyl H O 6-N-acetyl-2, 8-difluoroadenine H O-amino acid CH3 O-acyl H O 6-N-acetyl-2-aminoadenine H O-amino acid CH3 0-acyl H 0 6-N-acetyl-2-amino-8-fluoroadenine H O-amino acid CH3 O-acyl H O 2-N-acet laminoadenine H O-amino acid CH3 0-acyl H 0 2-N-acetylamino-8-fluoroadenine H 0-amino acid CH3 O-acyl H O 2-N-acetylamino-8-fluorohypoxanthine H O-amino acid CH3 O-acyl H O 2-N-acetylaminohy oxanthine H O-amino acid CH3 0-acyl H 0 Thymine H 0-acyl CH3 O-acyl H O Uracil H O-acyl CH3 O-acyl H O Guanine H O-acyl CH3 O-acyl H O Cytosine H O-acyl CH3 O-acyl H O Adenine H O-acyl CH3 O-acyl H O Hypoxanthine H O-acyl CH3 O-acyl H O 5-Fluorouracil H O-acyl CH3 O-acyl H O 8-Fluoroguanine H 0-acyl CH3 O-acyl H O 5-Fluorocytosine H O-ac 1 CH3 O-acyl H O 8-Fluoroadenine H O-acyl CH3 O-acyl H O 2-Fluoroadenine H O-acyl CH3 O-acyl H O 2, 8-Difluoroadenine H O-acyl CH3 0-acyl H 0 2-Fluorohypoxanthine H 0-acyl CH3 O-acyl H O 8-Fluorohy oxanthine H O-ac 1 CH3 O-acyl H O 2, 8-Difluorohypoxanthine H O-acyl CH3 O-acyl H O 2-Aminoadenine H O-ac 1 CH3 O-acyl H O 2-Amino-8-fluoroadenine H O-ac 1 CH3 O-acyl H O 2-Amino-8-fluorohypoxanthine H O-acyl CH3 O-acyl H O 2-Aminohypoxanthine H O-acyl CH3 0-acyl H 0 2-N-acetylguanine H 0-acyl CH3 O-acyl H O 4-N-acetylcytosine H O-acyl CH3 O-acyl H O 6-N-acetyladenine H O-acyl CH3 O-acyl H O 2-N-acetyl-8-fluoroguanine H O-acY CH3 O-acyl H O 4-N-acetyl-5-fluorocytosine H O-acY CH3 O-acyl H O 6-N-acetyl-2-fluoroadenine H O-acyl CH3 O-acyl H O 6-N-acetyl-2, 8-difluoroadenine H O-acyl CH3 O-acyl H O 6-N-acetyl-2-aminoadenine H O-acyl CH3 O-acyl H O 6-N-acetyl-2-amino-8-fluoroadenine H O-acyl CH3 O-acyl H O 2-N-acetylaminoadenine H O-acyl CH3 O-acyl H O 2-N-acetylamino-8-fluoroadenine H O-acyI CH3 O-acyl H O 2-N-acetylamino-8-fluorohypoxanthine H O-acyl CH3 O-acyl H O 2-N-acetylaminohypoxanthine H O-acyl Rfi R7 T X Base Rl° R9 CH3 O-acyl H O Thymine H OH CH3 O-acyl H O Uracil H OH CH3 O-acyl H O Guanine H OH CH3 O-acyl H O Cytosine H OH CH3 O-acyl H O Adenine H OH CH3 0-acyl H 0 Hypoxanthine H OH CH3 O-acyl H O 5-Fluorouraci I H OH CH3 O-acyl H O 8-Fluoroguanine H OH CH3 O-ac 1 H O 5-Fluoroc osine H OH CH3 O-acyl H O 8-Fluoroadenine H OH CH3 O-aceI H O 2-Fluoroadenine H OH CH3 O-acyl H O 2, 8-Difluoroadenine H OH CH3 O-acyl H O 2-Fluorohypoxanthine H OH CH3 O-acyl H O 8-Fluorohy oxanthine H OH CH3 O-acyl H O 2, 8-Difluorohypoxanthine H OH CH3 O-ac 1 H O 2-Aminoadenine H OH CH3 O-acyl H O 2-Amino-8-fluoroadenine H OH CH3 O-acyl H O 2-Amino-8-fluorohypoxanthine H OH CH3 O-ac I H O 2-Aminoh oxanthine H OH CH3 O-acyl H O 2-N-acetylguanine H OH CH3 0-acyl H O 4-N-acetylcytosine H OH CH3 O-acyl H O 6-N-acetyladenine H OH CH3 O-acyl H O 2-N-acetyl-8-fluoroguanine H OH CH3 O-acyl H O 4-N-acetyl-5-fluorocytosine H OH CH3 O-acyl H O 6-N-acetyl-2-fluoroadenine H OH CH3 O-acyl H O 6-N-acetyl-2, 8-difluoroadenine H OH CH3 O-acyl H O 6-N-acetyl-2-aminoadenine H OH CH3 0-acyl H O 6-N-acetyl-2-amino-8-fluoroadenine H OH CH3 O-acyl H O 2-N-acetylaminoadenine H OH CH3 O-acyl H O 2-N-acetylamino-8-fluoroadenine H OH CH3 O-acyl H O 2-N-acetylamino-8-fluorohypoxanthine H OH CH3 O-acyl H O 2-N-acetylaminohypoxanthine H OH CH3 O-acyl H O Thymine OH H CH3 O-acyl H O Uracil OH H CH3 O-acyl H O Guanine OH H CH3 O-acyl H 0 Cytosine OH H CH3 O-acyl H O Adenine OH H CH3 O-acyl H O Hypoxanthine OH H CH3 O-acyl H O 5-Fluorouracil OH H CH3 O-acyl H O 8-Fluoroguanine OH H CH3 O-acyl H O 5-Fluorocytosine OH H CH3 O-acyl H O 8-Fluoroadenine OH H CH3 O-acyl H O 2-Fluoroadenine OH H CH3 O-acyl H O 2, 8-Difluoroadenine OH H CH3 O-acyl H O 2-Fluorohypoxanthine OH H CH3 O-acyl H_ O 8-Fluorohypoxanthine OH H CH3 O-acyl H O 2, 8-Difluorohypoxanthine OH H R6 R 7 R8 X Base CH3 O-acyl H O 2-Aminoadenine OH H CH3 O-ac 1 H O 2-Amino-8-fluoroadenine OH H CH3 O-acyl H O 2-Amino-8-fluorohypoxanthine OH H CH3 O-acyl H 0 2-Aminohypoxanthine OH H CH3 O-acyl H 0 2-N-acetylguanine OH H CH3 O-acyl H O 4-N-acet lc osine OH H CH3 O-acyl H O 6-N-acetyladenine OH H CH3 O-ac 1 H O 2-N-acet 1-8-fluoro uanine OH H CH3 O-acyl H O 4-N-acetyl-5-fluorocytosine OH H CH3 O-acyl H O 6-N-acetyl-2-fluoroadenine OH H CH3 O-acyl H O 6-N-acetyl-2, 8-difluoroadenine OH H CH3 O-acyl H O 6-N-acetyl-2-aminoadenine OH H CH3 O-acyl H O 6-N-acetyl-2-amino-8-fluoroadenine OH H CH3 O-acyl H O 2-N-acetylaminoadenine OH H CH3 O-acyl H O 2-N-acetylamino-8-fluoroadenine OH H CH3 O-acyl H O 2-N-acetylamino-8-fluorohypoxanthine OH H CH3 0-acy ! H0 2-N-acetytaminohypoxanthineOH H CH3 O-amino acid F O Thymine F H CH3 O-amino acid F O Uracil F H CH3 O-amino acid F O Guanine F H CH3 O-amino acid F O Cytosine F H CH3 O-amino acid F O Adenine F H CH3 O-amino acid F O Hypoxanthine F H CH3 O-amino acid F O 5-Fluorouracil F H CH3 O-amino acid F O 8-Fluoroguanine F H CH3 O-amino acid F O 5-Fluoroc osine F H CH3 O-amino acid F O 8-Fluoroadenine F H CH3 O-amino acid F O 2-Fluoroadenine F H CH3 O-amino acid F O 2, 8-Difluoroadenine F H CH3 O-amino acid F 0 2-Fluorohypoxanthine F H CH3 O-amino acid F O 8-Fluorohy oxanthine F H CH3 O-amino acid F O 2, 8-Difluorohypoxanthine F H CH3 O-amino acid F O 2-Aminoadenine F H CH3 O-amino acid F O 2-Amino-8-fluoroadenine F H CH3 O-amino acid F O 2-Amino-8-fluorohypoxanthine F H CH3 O-amino acid F O 2-Aminohypoxanthine F H CH3 O-amino acid F O 2-N-acet 1 uanine F H CH3 O-amino acid F O 4-N-acetylcytosine F H CH3 O-amino acid F O 6-N-acetyladenine F H CH3 O-amino acid F O 2-N-acetyl-8-fluoroguanine F H CH3 O-amino acid F O 4-N-acetyl-5-fluoroc osine F H CH3 O-amino acid F O 6-N-acetyl-2-fluoroadenine F H CH3 O-amino acid F O 6-N-acetyl-2, 8-difluoroadenine F H CH3 O-amino acid F 0 6-N-acetyl-2-aminoadenine F H CH3 0-amino acid F O 6-N-acetyl-2-amino-8-fluoroadenine F H CH3 O-amino acid F O 2-N-acetylaminoadenine F H CH3 O-amino acid F O 2-N-acetylamino-8-fluoroadenine F H R R R X Base R R CH3 O-amino acid F O 2-N-acetylamino-8-fluorohypoxanthine F H CH3 0-amino acid F 0 2-N-acetylaminohypoxanthine F H CH3 0-amino acid F 0 Thymine F 0-amino acid CH3 O-amino acid F O Uracil F O-amino acid CH3 0-amino acid F O Guanine F O-amino acid CH3 O-amino acid F O Cytosine F O-amino acid CH3 O-amino acid F O Adenine F O-amino acid CH3 O-amino acid F O Hypoxanthine F O-amino acid CH3 O-amino acid F O 5-Fluorouracil F O-a_mino acid CH3 O-amino acid F O 8-Fluoroguanine F O-amino acid CH3 O-amino acid F O 5-Fluorocytosine F O-amino acid CH3 O-amino acid F O 8-Fluoroadenine F O-amino acid CH3 O-amino acid F O 2-Fluoroadenine F O-amino acid CH3 O-amino acid F O 2, 8-Difluoroadenine F O-amino acid CH3 0-amino acid F 0 2-Fluorohypoxanthine F 0-amino acid CH3 O-amino acid F O 8-Fluorohypoxanthine F O-amino acid CH3 O-amino acid F O 2, 8-Difluorohypoxanthine F 0-amino acid CH3 O-amino acid F O 2-Aminoadenine F O-amino acid CH3 O-amino acid F O 2-Amino-8-fluoroadenine F O-amino acid CH3 O-amino acid F O 2-Amino-8-fluorohypoxanthine F O-amino acid CH3 O-amino acid F O 2-Aminohypoxanthine F O-amino acid CH3 O-amino acid F O 2-N-acetylguanine F O-amino acid CH3 O-amino acid F O 4-N-acetylcytosine F O-amino acid CH3 O-amino acid F O 6-N-acetyladenine F O-amino acid CH3 O-amino acid F O 2-N-acetyl-8-fluoroguanine _ F O-amino acid CH3 O-amino acid F O 4-N-acetyl-5-fluorocytosine F O-amino acid CH3 0-amino acid F 0 6-N-acetyl-2-fluoroadenine F 0-amino acid CH3 O-amino acid F O 6-N-acety1-2, 8-difluoroadenine F O-amino acid CH3 O-amino acid F O 6-N-acetyl-2-aminoadenine F O-amino acid CH3 O-aminoiacid F O 6-N-acetyl-2-amino-8-fluoroadenine F O-amino acid CH3 O-amino acid F O 2-N-acetylaminoadenine F O-amino acid CH3 O-amino acid F O 2-N-acetylamino-8-fluoroadenine F O-amino acid CH3 0-amino acid F 0 2-N-acetylamino-8-fluorohypoxanthine F 0-amino acid CH3 O-amino acid F O 2-N-acetylaminohypoxanthine F O-amino acid O-amino acid F O Thymine F O-acyl CH3 0-amino acid F O Uracil F O-acyl CH3 O-amino acid F O Guanine F O-acyl CH3 0-amino acid F O Cytosine F O-acyl CH3 0-amino acid F 0 Adenine F 0-acyl CH3 0-amino acid F O Hypoxanthine F O-acyl CH3 0-amino acid F O 5-Fluorouracil F O-acyl CH3 0-amino acid F O 8-Fluoroguanine F O-acyl CH3 O-amino acid F O 5-Fluorocytosine F O-acyl CH3 0-amino acid F O 8-Fluoroadenine F O-acyI CH3 0-amino acid F 0 2-Fluoroadenine F-acyl CH3 O-amino acid F O 2, 8-Difluoroadenine F 0-acyl CH3 O-amino acid F O 2-Fluorohypoxanthine F O-acyl R"R'R X Base R'° Ry CH3 O-amino acid F O 8-Fluorohypoxanthine F O-acyl CH3 O-amino acid F O 2, 8-Difluorohypoxanthine F O-acyl CH3 O-amino acid F O 2-Aminoadenine F O-acyI CH3 O-amino acid F O 2-Amino-8-fluoroadenine F O-acyl CH3 O-amino acid F O 2-Amino-8-fluorohypoxanthine F O-acyl CH3 0-amino acid F O 2-Aminohypoxanthine F O-acyl CH3 0-amino acid F O 2-N-acetylguanine F O-acyl CH3 0-amino acid F O 4-N-acetylcytosine _ _ F O-acyl CH3 0-amino acid F0 6-N-acetyladenineF0-acyl CH3 0-amino acid F O 2-N-acetyl-8-fluoroguanine F O-acyl CH3 0-amino acid F O 4-N-acetyl-5-fluorocYtosine F O-acY CH3 O-amino acid F O 6-N-acetyl-2-fluoroadenine F O-acyl CH3 O-amino acid F O 6-N-acetyl-2, 8-difluoroadenine F O-acyl CH3 0-amino acid F O 6-N-acetyl-2-aminoadenine F O-acYl CH3 0-amino acid F O 6-N-acetyl-2-amino-8-fluoroadenine F O-acyl CH3 O-amino acid F O 2-N-acetylaminoadenine F O-ac 1 CH3 O-amino acid F O 2-N-acetylamino-8-fluoroadenine F O-acyl CH3 O-amino acid F O 2-N-acetylamino-8-fluorohypoxanthine F O-acyl CH3 0-amino acid F O 2-N-acetylaminohypoxanthine F O-acyl CH3 O-amino acid F O Thymine F OH CH3 O-amino acid F O Uracil F OH CH3 O-amino acid F O Guanine F OH CH3 O-amino acid F O Cytosine F OH CH3 O-amino acid F O Adenine F OH CH3 O-amino acid F O Hypoxanthine F OH CH3 O-amino acid F O 5-Fluorouracil F OH CH3 O-amino acid F O 8-Fluoroguanine F OH CH3 O-amino acid F O 5-Fluorocytosine F OH CH3 0-amino acid F 0 8-Fluoroadenine F OH CH3 O-amino acid F O 2-Fluoroadenine F OH CH3 O-amino acid F O 2, 8-Difluoroadenine F OH CH3 O-amino acid F O 2-Fluorohypoxanthine F OH CH3 O-am ino acid F O 8-Fluorohypoxanthine F OH CH3 O-amino acid F O 2, 8-Difluorohypoxanthine F OH CH3 O-amino acid F O 2-Aminoadenine F OH CH3 O-amino acid F O 2-Amino-8-fluoroadenine F OH CH3 O-amino acid F O 2-Amino-8-fluorohypoxanthine F OH CH3 0-amino acid F 0 2-Aminohypoxanthine F OH CH3 O-amino acid F O 2-N-acetylguanine F OH CH3 O-amino acid F O 4-N-acetylc osine F OH CH3 0-amino acid F O 6-N-acetyladenine F OH CH3 0-amino acid F O 2-N-acetyl-8-fluoroguanine F OH CH3 0-amino acid F O 4-N-acetyl-5-fluorocytosine F OH CH3 0-amino acid F O 6-N-acetyl-2-fluoroadenine F OH CH3 O-amino acid F O 6-N-acetyl-2, 8-difluoroadenine F OH CH3 0-amino acid F 0 6-N-acetyl-2-aminoadenine F OH CH3 O-amino acid F O 6-N-acetyl-2-am ino-8-fluoroadenine F OH R R R X Base Rl° RY CH3 O-amino acid F O 2-N-acetylaminoadenine F OH CH3 O-amino acid F O 2-N-acetylamino-8-fluoroadenine F OH CH3 O-amino acid F O 2-N-acetylamino-8-fluorohypoxanthine F OH CH3 0-amino acid F O 2-N-acetylaminohypoxanthine F OH CH3 0-amino acid F 0 Thymine Br H CH3 O-amino acid F O Uracil Br H CH3 0-amino acid F 0 Guanine Br H CH3 O-amino acid F O Cytosine Br H CH3 O-amino acid F O Adenine Br H CH3 0-amino acid F 0 Hypoxanthine Br H CH3 O-amino acid F O 5-Fluorouracil Br H CH3 O-amino acid F O 8-Fluoroguanine Br H CH3 O-amino acid F O 5-Fluorocytosine Br H CH3 O-amino acid F O 8-Fluoroadenine Br H CH3 O-amino acid F O 2-Fluoroadenine Br H CH3 O-amino acid F O 2, 8-Difluoroadenine Br H CH3 O-amino acid F 0 2-Fluorohypoxanthine Br H CH3 O-amino acid F O 8-Fluorohy oxanthine Br H CH3 O-amino acid F O 2, 8-Difluorohypoxanthine Br H CH3 O-amino acid F O 2-Aminoadenine Br H CH3 0-amino acid F O 2-Amino-8-fluoroadenine Br H CH3 0-amino acid F O 2-Amino-8-fluorohypoxanthine Br H CH3 0-amino acid F O 2-Aminohypoxanthine Br H CH3 O-amino acid F O 2-N-acetylguanine Br H CH3 O-amino acid F O 4-N-acetylcytosine Br H CH3 0-amino acid F 0 6-N-acetyladenine Br H CH3 O-amino acid F O 2-N-acetyl-8-fluoroguanine Br H CH3 0-amino acid F O 4-N-acetyl-5-fluorocytosine Br H CH3 0-amino acid F O 6-N-acetyl-2-fluoroadenine Br H CH3 0-amino acid F O 6-N-acetyl-2, 8-difluoroadenine Br H CH3 O-amino acid F O 6-N-acetyl-2-aminoadenine Br H CH3 O-amino acid F O 6-N-acetyl-2-amino-8-fluoroadenine Br H CH3 0-amino acid F 0 2-N-acetylaminoadenine Br H CH3 O-amino acid F O 2-N-acetylamino-8-fluoroadenine Br H CH3 O-amino acid F O 2-N-acetylamino-8-fluorohypoxanthine Br H CH3 O-amino acid F O 2-N-acetylaminohypoxanthine Br H CH3 O-amino acid F O Thymine Br O-amino acid CH3 O-amino acid F O Uracil Br O-amino acid CH3 O-amino acid F O Guanine Br O-amino acid CH3 O-amino acid F O Cytosine Br O-amino acid CH3 O-amino acid F O Adenine Br O-amino acid CH3 O-amino acid F O Hypoxanthine Br O-amino acid CH3 O-amino acid F O 5-Fluorouracil Br O-amino acid CH3 O-amino acid F O 8-Fluoro uanine Br O-amino acid CH3 O-amino acid F O 5-Fluoroc osine Br O-amino acid CH3 O-amino acid F O 8-Fluoroadenine Br O-amino acid CH3 O-amino acid F O 2-Fiuoroadenine Br O-amino acid F R7 F X Base R R CH3 O-amino acid F O 2, 8-Difluoroadenine Br O-amino acid CH3 O-amino acid F Q 2-Fluorohypoxanthine Br O-amino acid CH3 O-amino acid F O 8-Fluorohypoxanthine Br O-amino acid CH3 O-amino acid F O 2, 8-Difluorohypoxanthine Br O-amino acid CH3 O-amino acid F O 2-Aminoadenine Br O-amino acid CH3 O-amino acid F O 2-Amino-8-fluoroadenine Br O-amino acid CH3 O-amino acid F O 2-Amino-8-fluorohypoxanthine Br O-amino acid CH3 O-amino acid F O 2-Aminohypoxanthine Br O-amino acid CH3 O-amino acid F O 2-N-acetylguanine Br O-amino acid CH3 O-amino acid F O z Br O-amino acid CH3 O-amino acid F O 6-N-acetyladenine Br O-amino acid CH3 O-amino acid F O 2-N-acetyl-8-fluoroguanine Br O-amino acid CH3 O-amino acid F O 4-N-acetyl-5-fluorocytosine Br O-amino acid CH3 O-amino acid F O 6-N-acetyl-2-fluoroadenine Br O-amino acid CH3 0-amino acid F O 6-N-acetyl-2, 8-difluoroadenine Br O-amino acid CH3 O-amino acid F O 6-N-acetyl-2-aminoadenine Br O-amino acid CH3 O-amino acid F O 6-N-acetyl-2-amino-8-fluoroadenine Br O-amino acid CH3 O-amino acid F O 2-N-acetylaminoadenine Br O-amino acid CH3 O-amino acid F O 2-N-acetylamino-8-fluoroadenine Br O-amino acid CH3 O-amino acid F O 2-N-acetylamino-8-fluorohypoxanthine Br O-amino acid CH3 0-amino acid F 0 2-N-acetylaminohypoxanthine Br 0-amino acid CH3 0-amino acid F 0 Thymine Br 0-acyl CH3 O-amino acid F O Uracil Br O-acyl CH3 O-amino acid F O Guanine Br O-acyl CH3 O-amino acid F O Cytosine Br O-acyl CH3 0-amino acid F 0 Adenine Br 0-acyl CH3 O-amino acid F O Hypoxanthine Br O-acyl CH3 O-amino acid F O 5-Fluorouracil Br O-acyl CH3 O-amino acid F O 8-Fluoroguanine Br O-acyl CH3 O-amino acid F O 5-Fluoroc osine Br O-acyl CH3 O-amino acid F O 8-Fluoroadenine Br O-acyl CH3 O-amino acid F O 2-Fluoroadenine Br O-acyl CH3 O-amino acid F O 2, 8-Difluoroadenine Br O-acyl CH3 0-amino acid F 0 2-Fluorohypoxanthine Br 0-acyl CH3 O-amino acid F O 8-FluorohyDoxanthine Br O-acvl CH3 O-amino acid F O 2, 8-Difluorohypoxanthine Br O-acyl CH3 O-amino acid F O 2-Aminoadenine Br O-acyl CH3 O-amino acid F O 2-Amino-8-fluoroadenine Br O-acyl CH3 O-amino acid F O 2-Amino-8-fluorohypoxanthine Br O-acyl CH3 O-amino acid F O 2-Aminohypoxanthine Br O-acyl CH3 0-amino acid F 0 2-N-acetylguanine Br 0-acyl CH3 O-amino acid F O 4-N-acetylcytosine Br O-acyl CH3 0-amino acid F O 6-N-acetyladenine Br O-acyl CH3 O-amino acid F O 2-N-acetyl-8-fluoroguanine Br O-acyl CH3 O-amino acid F O 4-N-acetyl-S-fluorocytosine Br O-acyI CH3 O-amino acid F O 6-N-acetyl-2-fluoroadenine Br O-acvl CH3 O-amino acid F O 6-N-acetyl-2, 8-difluoroadenine Br O-acyl R R R X Base R R CH3 0-amino acid F O 6-N-acetyl-2-aminoadenine Br O-acyI CH3 0-amino acid F O 6-N-acetyl-2-amino-8-fluoroadenine Br O-acyl CH3 O-amino acid F O 2-N-acetylaminoadenine Br O-acyl CH3 0-amino acid F O 2-N-acetylamino-8-fluoroadenine Br _-acyl CH3 0-amino acid F O 2-N-acetylamino-8-fluorohypoxanthine Br 0-acyl CH3 0-amino acid F 0 2-N-acetylaminohypoxanthine Br 0-acyl CH3 0-amino acid F O Thymine Br OH CH3 0-amino acid F O Uracil Br OH CH3 0-amino acid F O Guanine Br OH CH3 0-amino acid F O Cytosine Br OH CH3 0-amino acid F O Adenine Br OH CH3 0-amino acid F O Hypoxanthine Br OH CH3 0-amino acid F O S-Fluorouracil Br OH CH3 O-amino acid F O 8-Fluoroguanine Br OH CH3 0-amino acid F O 5-Fluorocytosine Br OH CH3 0-amino acid F O 8-Fluoroadenine Br OH CH3 0-amino acid F 0 2-Fluoroadenine Br OH CH3 0-amino acid F O 2, 8-Difluoroadenine Br OH CH3 0-amino acid F O 2-Fluorohypoxanthine Br OH CH3 0-amino acid F O 8-Fluorohypoxanthine Br OH CH3 O-amino acid F O 2, 8-Difluorohypoxanthine Br OH CH3 O-amino acid F O 2-Aminoadenine Br OH CH3 0-amino acid F O 2-Amino-8-fluoroadenine Br OH CH3 0-amino acid F O 2-Amino-8-fluorohypoxanthine Br OH CH3 0-amino acid F O 2-Aminoh oxanthine Br OH CH3 0-amino acid F 0 2-N-acetyl guanine Br OH CH3 0-amino acid F O 4-N-acetylcytosine Br OH CH3 O-amino acid F O 6-N-acetyladenine Br OH CH3 0-amino acid F O 2-N-acetyl-8-fluoroguanine Br OH CH3 O-amino acid F O 4-N-acet 1-5-fluorocytosine Br OH CH3 0-amino acid F O 6-N-acetyl-2-fluoroadenine Br OH CH3 O-amino acid F O 6-N-acetyl-2, 8-difluoroadenine Br OH CH3 0-amino acid F O 6-N-acetyl-2-aminoadenine Br OH CH3 O-amino acid F O 6-N-acetyl-2-amino-8-fluoroadenine Br OH CH3 0-amino acid F 0 2-N-acetylaminoadenine Br OH CH3 O-amino acid F 0 2-N-acetylamino-8-fluoroadenine Br OH CH3 0-amino acid F 0 2-N-acetylamino-8-fluorohypoxanthine Br OH CH3 0-amino acid F O 2-N-acetylaminohypoxanthine Br OH CH3 0-amino acid F O Thymine Cl H CH3 O-amino acid F O Uracil Cl H CH3 0-amino acid F O Guanine Cl H CH3 0-amino acid F O Cytosine Cl H CH3 0-amino acid F O Adenine Cl H CH3 0-amino acid F O Hypoxanthine Cl H CH3 0-amino acid F O 5-Fluorouracil Cl H CH3 0-amino acid F O 8-Fluoroguanine Cl H CH3 0-amino acid F O S-Fluorocytosine Cl H R R X Base Rl° R9 CH3 O-amino acid F O 8-Fluoroadenine Cl H CH3 O-amino acid F O 2-Fluoroadenine Cl H CH3 O-amino acid F O 2, 8-Difluoroadenine Cl H CH3 O-amino acid F O 2-Fluorohypoxanthine Cl H CH3 O-amino acid F O 8-Fluorohypoxanthine Cl H CH3 O-amino acid F O 2, 8-Difluorohypoxanthine Cl H CH3 O-amino acid F O 2-Aminoadenine Cl H CH3 O-amino acid F O 2-Amino-8-fluoroadenine Cl H CH3 O-amino acid F O 2-Amino-8-fluorohypoxanthine Cl H CH3 0-amino acid F 0 2-Aminoh oxanthine Cl H CH3 O-amino acid F O 2-N-acetylguanine Cl H CH3 O-amino acid F O 4-N-acetylcytosine CI H CH3 O-amino acid F O 6-N-acetyladenine Cl H CH3 O-amino acid F O 2-N-acetyl-8-fluoroguanine Cl H CH3 O-amino acid F O 4-N-acetyl-5-fluorocytosine Cl H CH3 O-amino acid F O 6-N-acetyl-2-fluoroadenine Cl H CH3 O-amino acid F 0 6-N-acetyl-2, 8-difluoroadenine Cl H CH3 O-amino acid F O 6-N-acetyl-2-aminoadenine Cl H CH3 0-amino acid F 0 6-N-acetyl-2-amino-8-fluoroadenine Cl H CH3 O-amino acid F O 2-N-acetylaminoadenine Cl CH3 O-amino acid F O 2-N-acetylamino-8-fluoroadenine Cl H CH3 O-amino acid F O 2-N-acetylamino-8-fluorohypoxanthine C I H CH3 O-amino acid F O 2-N-acetylaminohypoxanthine Cl H CH3 O-amino acid F O Thymine Cl O-amino acid CH3 O-amino acid F O Uracil Cl O-amino acid CH3 O-amino acid F O Guanine Cl O-amino acid CH3 O-amino acid F O Cytosine Cl O-amino acid CH3 O-amino acid F O Adenine Cl O-amino acid CH3 O-amino acid F O Hypoxanthine CI O-amino acid CH3 O-amino acid F O 5-Fluorouracil Cl O-amino acid CH3 O-amino acid F O 8-Fluoroguanine Cl O-amino acid CH3 O-amino acid F O 5-Fluoroc osine CI O-amino acid CH3 O-amino acid F O 8-Fluoroadenine Cl O-amino acid CH3 O-amino acid F O 2-Fluoroadenine Cl O-amino acid CH3 O-amino acid F O 2, 8-Difluoroadenine Cl O-amino acid CH3 O-amino acid F O 2-Fluorohypoxanthine Cl O-amino acid CH3 O-amino acid F O 8-Fluoroh oxanthine C1 O-amino acid CH3 O-amino acid F O 2, 8-Difluorohypoxanthine Cl O-amino acid CH3 O-amino acid F O 2-Aminoadenine Cl O-amino acid CH3 O-amino acid F O 2-Amino-8-fluoroadenine Cl O-amino acid CH3 O-amino acid F O 2-Amino-8-fluorohypoxanthine Cl O-amino acid CH3 O-amino acid F O 2-Aminohypoxanthine Cl O-amino acid CH3 O-amino acid F O 2-N-acetylguanine Cl O-amino acid CH3 O-amino acid F O 4-N-acetylcytosine CI O-amino acid CH3 O-amino acid F O 6-N-acetyladenine Cl O-amino acid CH3 O-amino acid F O 2-N-acetyl-8-fluoroguanine Cl O-amino acid CH3 O-amino acid F O 4-N-acet 1-5-fluorocytosine Cl O-amino acid T R7 T X Base R R CH3 O-amino acid F O 6-N-acetyl-2-fluoroadenine Cl O-amino acid CH3 O-amino acid F O 6-N-acetyl-2, 8-difluoroadenine Cl O-amino acid CH3 O-amino acid F O 6-N-acetyl-2-aminoadenine Cl O-amino acid CH3 O-amino acid F 0X 6-N-acetyl-2-amino-8-fluoroadenine Cl O-amino acid CH3 O-amino acid F 0 2-N-acetylaminoadenine Cl 0-amino acid CH3 0-amino acid F O 2-N-acetylamino-8-fluoroadenine Cl O-amino acid CH3 O-amino acid F 0 2-N-acetylamino-8-fluorohypoxanthine Cl 0-amino acid CH3 O-amino acid F O 2-N-acetylaminohypoxanthine Cl O-amino acid CH3 0-amino acid F O Thymine Cl O-acyl CH3 0-amino acid F O Uracil Cl O-acyl CH3 O-amino acid F O Guanine Cl O-acy1 CH3 0-amino acid F O Cytosine Cl O-acyl CH3 O-amino acid F O Adenine Cl O-acyl CH3 O-amino acid F O Hypoxanthine Cl O-acyl CH3 0-amino acid F O 5-Fluorouracil C1 O-acyl CH3 0-amino acid F O 8-Fluoroguanine Cl O-acyl CH3 O-amino acid F O S-Fluorocytosine Cl O-acyl CH3 0-amino acid F O 8-Fluoroadenine C1 O-acyl CH3 O-amino acid F O 2-Fluoroadenine Cl O-acyl CH3 0-amino acid F O 2, 8-Difluoroadenine Cl O-acyl CH3 O-amino acid F O 2-Fluorohypoxanthine Cl O-acyl CH3 0-amino acid F O 8-Fluorohypoxanthine Cl O-acyl CH3 O-amino acid F O 2, 8-Difluorohypoxanthine Cl O-acyl CH3 O-amino acid F O 2-Aminoadenine C1 O-ac 1 CH3 O-amino acid F O 2-Amino-8-fluoroadenine Cl O-acyl CH3 O-amino acid F O 2-Amino-8-fluorohypoxanthine Cl O-acyl CH3 O-amino acid F O 2-Aminohy oxanthine CI O-ac 1 CH3 0-amino acid F O 2-N-acet I uanine C1 O-acyl CH3 0-amino acid F O 4-N-acetylcytosine C1 O-ac I CH3 0-amino acid F O 6-N-acetyladenine Cl O-acyl CH3 0-amino acid F O 2-N-acetyl-8-fluoroguanine Cl O-acyl CH3 O-amino acid F O 4-N-acetyl-5-fluorocytosine CI O-ac 1 CH3 O-amino acid F O 6-N-acetyl-2-fluoroadenine Cl O-acyl CH3 0-amino acid F O 6-N-acetyl-2, 8-difluoroadenine Cl O-acyl CH3 O-amino acid F O 6-N-acetyl-2-aminoadenine Cl O-acy1 CH3 O-amino acid F O 6-N-acetyl-2-amino-8-fluoroadenine Cl O-acyl CH3 O-amino acid F O 2-N-acet laminoadenine Cl O-acyl CH3 0-amino acid F O 2-N-acetylamino-8-fluoroadenine Cl O-acyl CH3 0-amino acid F O 2-N-acetylamino-8-fluorohypoxanthine Cl O-acyl CH3 0-amino acid F O 2-N-acetylaminohypoxanthine Cl O-acyl CH3 0-amino acid F O Thymine Cl OH CH3 0-amino acid F O Uracil Cl OH CH3 0-amino acid F O Guanine Cl OH CH3 0-amino acid F O Cytosine Cl OH CH3 O-amino acid F 0 Adenine Cl OH CH3 0-amino acid F O Hypoxanthine Cl OH CH3 0-amino acid F O 5-Fluorouracil Cl OH R"R'R X Base R R9 CH3 O-amino acid F O 8-Fluoroguanine Cl OH CH3 O-amino acid F O S-Fluorocytosine Cl OH CH3 O-amino acid F O 8-Fluoroadenine Cl OH CH3 O-amino acid F O 2-Fluoroadenine Cl OH CH3 O-amino acid F O 2, 8-Difluoroadenine Cl OH CH3 O-amino acid F O 2-Fluorohypoxanthine Cl OH CH3 O-amino acid F O 8-Fluorohypoxanthine Cl OH CH3 O-amino acid F O 2, 8-Difluorohypoxanthine Cl OH CH3 O-amino acid F O 2-Aminoadenine Cl OH CH3 O-amino acid F O 2-Amino-8-fluoroadenine Cl OH CH3 0-amino acid F 0 2-Amino-8-fluorohypoxanthine Cl OH CH3 O-amino acid F O 2-Aminohypoxanthine Cl OH CH3 0-amino acid F O 2-N-acetylguanine Cl OH CH3 O-amino acid F O 4-N-acetylcytosine Cl OH CH3 O-amino acid F O 6-N-acetyladenine Cl OH CH3 O-amino acid F O 2-N-acetyl-8-fluoroguanine Cl OH CH3 O-amino acid F O 4-N-acetyl-S-fluorocytosine Cl OH CH3 O-amino acid F 0 6-N-acetyl-2-fluoroadenine Cl OH CH3 O-amino acid F O 6-N-acetyl-2, 8-difluoroadenine Cl OH CH3 O-amino acid F O 6-N-acetyl-2-aminoadenine Cl OH CH3 O-amino acid F O 6-N-acetyl-2-amino-8-fluoroadenine Cl OH CH3 O-amino acid F O 2-N-acetylaminoadenine C1 OH CH3 0-amino acid F O 2-N-acetylamino-8-fluoroadenine C I OH CH3 O-amino acid F O 2-N-acetylamino-8-fluorohypoxanthine Cl OH CH3 O-amino acid F O 2-N-acetylaminohypoxanthine C I OH CH3 0-amino acid F 10 1 Thymine H H CH3 O-amino acid F O Uracil H H CH3 0-amino acid F O Guanine H H CH3 O-amino acid F O Cytosine H H CH3 O-amino acid F O Adenine H H CH3 O-amino acid F O Hypoxanthine H H CH3 O-amino acid F O 5-Fluorouracil H H CH3 O-amino acid F O 8-Fluoroguanine H H CH3 O-amino acid F O 5-Fluorocytosine H H CH3 0-amino acid F O 8-Fluoroadenine H H CH3 O-amino acid F O 2-Fluoroadenine H H CH3 O-amino acid F O 2, 8-Difluoroadenine H H CH3 0-amino acid F 0 2-Fluorohypoxanthine H H CH3 0-amino acid F0 8-FluorohypoxanthineH H CH3 O-amino acid F O 2, 8-Difluorohypoxanthine H H CH3 O-amino acid F O 2-Aminoadenine H H CH3 O-amino acid F O 2-Amino-8-fluoroadenine H H CH3 0-amino acid F O 2-Amino-8-fluorohypoxanthine H H CH3 0-amino acid F O 2-Aminohypoxanthine H H CH3 0-amino acid F O 2-N-acetylguanine H H CH3 O-amino acid F O 4-N-acet lcytosine H H CH3 O-amino acid F 0 6-N-acetyladenine H H R6 R7 RS X Base Rlo IR9 CH3 O-amino acid F O 2-N-acetyl-8-fluoroguanine H H CH3 O-amino acid F O 4-N-acet I-5-fluorocytosine H H CH3 O-amino acid F O 6-N-acetyl-2-fluoroadenine H H CH3 O-amino acid F O 6-N-acetyl-2, 8-difluoroadenine H H CH3 O-amino acid F O 6-N-acetyl-2-aminoadenine H H CH3 O-amino acid F O 6-N-acetyl-2-amino-8-fluoroadenine H H CH3 0-amino acid F 0 2-N-acetylaminoadenine H H CH3 0-amino acid F 0 2-N-acetylamino-8-fluoroadenine H H CH3 O-amino acid F O 2-N-acetylamino-8-fluorohypoxanthine H H CH3 0-amino acid F 0 2-N-acetylaminohypoxanthine H H CH3 O-amino acid F O Thymine H O-amino acid CH3 O-amino acid F O Uracil H O-amino acid CH3 O-amino acid F O Guanine H O-amino acid CH3 O-amino acid F O Cytosine H O-amino acid CH3 O-amino acid F O Adenine H O-amino acid CH3 0-amino acid F O Hypoxanthine H O-amino acid CH3 0-amino acid F O 5-Fluorouracil H O-amino acid CH3 O-amino acid F O 8-Fluoroguanine H O-amino acid CH3 O-amino acid F O 5-Fluorocytosine H O-amino acid CH3 O-amino acid F O 8-Fluoroadenine H O-amino acid CH3 O-amino acid F O 2-Fluoroadenine H O-amino acid CH3 O-amino acid F O 2, 8-Difluoroadenine H O-amino acid CH3 O-amino acid F O 2-Fluorohypoxanthine H O-amino acid CH3 O-amino acid F O 8-Fluorohypoxanthine H O-amino acid CH3 O-amino acid F O 2, 8-Difluorohypoxanthine H 0-amino acid CH3 O-amino acid F O 2-Aminoadenine H O-amino acid CH3 O-amino acid F O 2-Amino-8-fluoroadenine H O-amino acid CH3 O-amino acid F O 2-Amino-8-fluorohypoxanthine H O-amino acid CH3 0-amino acid F 0 2-Aminohypoxanthine H 0-amino acid CH3 O-amino acid F O 2-N-acetylguanine H O-amino acid CH3 O-amino acid F O 4-N-acetylc osine H O-amino acid CH3 0-amino acid F 0 6-N-acetyladenine H 0-amino acid CH3 0-amino acid F O 2-N-acetyl-8-fluoroguanine H O-amino acid CH3 0-amino acid F O 4-N-acetyl-5-fluorocytosine H O-amino acid CH3 0-amino acid F O 6-N-acetyl-2-fluoroadenine H O-amino acid CH3 O-amino acid F O 6-N-acetyl-2, 8-difluoroadenine H O-amino acid CH3 0-amino acid F O 6-N-acetyl-2-aminoadenine H O-amino acid CH3 O-amino acid F O 6-N-acetyl-2-amino-8-fluoroadenine H O-amino acid CH3 O-amino acid F O 2-N-acetylaminoadenine H O-amino acid CH3 O-amino acid F O 2-N-acetylamino-8-fluoroadenine H O-amino acid CH3 O-amino acid F O 2-N-acetylamino-8-fluorohypoxanthine H O-amino acid CH3 O-amino acid F O 2-N-acetylaminohypoxanthine H O-amino acid CH3 O-amino acid F O Thymine H O-acyl CH3 O-amino acid F O Uracil H O-acyl CH3 0-amino acid F 0 Guanine H 0-acyl CH3 O-amino acid F O Cytosine H O-acyl CH3 O-amino acid F O Adenine H O-acyl R6 R'R° X Base R R CH3 O-amino acid F O Hypoxanthine H O-acyl CH3 O-amino acid F O 5-Fluorouracil H O-acyl CH3 0-amino acid F O 8-Fluoroguanine H O-ac 1 CH3 0-amino acid F O 5-Fluorocytosine H O-ac 1 CH3 O-amino acid F O 8-Fluoroadenine H O-ac 1 CH3 O-amino acid F O 2-Fluoroadenine H O-ac 1 CH3 0-amino acid F 0 2, 8-Difluoroadenine H 0-acyl CH3 O-amino acid F O 2-Fluorohypoxanthine H O-acyl CH3 O-amino acid F O 8-Fluoroh oxanthine H O-acyl CH3 O-amino acid F O 2, 8-Difluorohypoxanthine H O-acyl CH3 O-amino acid F O 2-Aminoadenine H O-acyl CH3 O-amino acid F O 2-Amino-8-fluoroadenine H O-acyl CH3 O-amino acid F O 2-Amino-8-fluorohypoxanthine H O-acyl CH3 0-amino acid F 0 2-Aminohypoxanthine H 0-acyl CH3 O-amino acid F O 2-N-acetylguanine H O-acyl CH3 O-amino acid F O 4-N-acetylcytosine H O-acyl CH3 O-amino acid F O 6-N-acetyladenine H O-acyl CH3 O-amino acid F O 2-N-acetyl-8-fluoroguanine H O-acyl CH3 O-amino acid F O 4-N-acetyl-5-fluoroc osine H O-acyl CH3 O-amino acid F O 6-N-acetyl-2-fluoroadenine H O-acyl CH3 O-amino acid F O 6-N-acetyl-2, 8-difluoroadenine H O-acyl CH3 O-amino acid F O 6-N-acet 1-2-aminoadenine H O-ac 1 CH3 O-amino acid F O 6-N-acetyl-2-amino-8-fluoroadenine H O-acyl CH3 O-amino acid F O 2-N-acetylaminoadenine H O-acyl CH3 0-amino acid F 0 2-N-acetylamino-8-fluoroadenine H 0-acyl CH3 O-amino acid F O 2-N-acetylamino-8-fluorohypoxanthine H O-acyl CH3 O-amino acid F O 2-N-acetylaminohypoxanthine H O-acyl CH3 O-amino acid F O Thymine H OH CH3 O-amino acid F O Uracil H OH CH3 O-amino acid F O Guanine H OH CH3 O-amino acid F O Cytosine H OH CH3 O-amino acid F O Adenine H OH CH3 0-amino acid F O Hypoxanthine H OH CH3 0-amino acid F 0 5-Fluorouracil H OH CH3 O-amino acid F O 8-Fluoro uanine H OH CH3 O-amino acid F O 5-Fluorocytosine H OH CH3 O-amino acid F O 8-Fluoroadenine H OH CH3 O-amino acid F O 2-Fluoroadenine H OH CH3 O-amino acid F O 2, 8-Difluoroadenine H OH CH3 O-amino acid F O 2-Fluorohypoxanthine. H OH CH3 0-amino acid F O 8-Fluoroh oxanthine H OH CH3 0-amino acid F O 2, 8-Difluorohypoxanthine H OH CH3 O-amino acid F O 2-Aminoadenine H OH CH3 O-amino acid F O 2-Amino-8-fluoroadenine H OH CH3 0-amino acid F 0 2-Amino-8-fluorohypoxanthine H OH CH3 O-amino acid F O 2-Aminohypoxanthine H OH CH3 O-amino acid F O 2-N-acetylguanine H OH R6 R 7 R8 X Base R R CH3 O-amino acid F O 4-N-acetylcytosine H OH CH3 O-amino acid F 0 6-N-acetyladenine H OH CH3 O-amino acid F O 2-N-acet I-8-fluoroguanine H OH CH3 O-amino acid F O 4-N-acetyl-5-fluorocytosine H OH CH3 O-amino acid F O 6-N-acetyl-2-fluoroadenine H OH CH3 O-amino acid F O 6-N-acetyl-2, 8-difluoroadenine H OH CH3 O-amino acid F O 6-N-acetyl-2-aminoadenine H OH CH3 O-amino acid F m 6-N-acetyl-2-amino-8-fluoroadenine H OH CH3 0-amino acid F O 2-N-acetylaminoadenine H OH CH3 O-amino acid F O 2-N-acetylamino-8-fluoroadenine H OH CH3 O-amino acid F O 2-N-acetylamino-8-fluorohypoxanthine H OH CH3 O-amino acid F O 2-N-acetylaminohypoxanthine H OH CH3 0-amino acid F 0 Thymine OH H CH3 O-amino acid F O Uracil OH H CH3 O-amino acid F O Guanine OH H CH3 O-amino acid F O Cytosine OH H CH3 O-amino acid F O Adenine OH H CH3 O-amino acid F 0 Hypoxanthine OH H CH3 O-amino acid F O 5-Fluorouracil OH H CH3 0-amino acid F 0 8-Fluoroguanine OH H CH3 0-amino acid F O 5-Fluoroc osine OH H CH3 O-amino acid F O 8-Fluoroadenine OH H CH3 O-amino acid F O 2-Fluoroadenine OH H CH3 O-amino acid F O 2, 8-Difluoroadenine OH H CH3 0-amino acid F 0 2-Fluorohypoxanthine OH H CH3 O-amino acid F O 8-Fluoroh oxanthine OH H CH3 O-amino acid F'O 2, 8-Difluorohypoxanthine OH H CH3 0-amino acid F 0 2-Aminoadenine OH H CH3 O-amino acid F O 2-Amino-8-fluoroadenine OH H CH3 0-amino acid F 0 2-Amino-8-fluorohypoxanthine OH H CH3 0-aminoacid F0 2-AminohypoxanthineOH H CH3 0-amino acid F 0 2-N-acetylguanine OH H CH3 O-amino acid F O 4-N-acetylc osine OH H CH3 O-amino acid F O 6-N-acetyladenine OH H CH3 O-amino acid F O 2-N-acetyl-8-fluoroguanine OH H CH3 O-amino acid F O 4-N-acetyl-5-fluorocytosine OH H CH3 O-amino acid F 0 6-N-acetyl-2-fluoroadenine OH H CH3 O-amino acid F O 6-N-acetyl-2, 8-difluoroadenine OH H CH3 O-amino acid F O 6-N-acetyl-2-aminoadenine OH H CH3 O-amino acid F O 6-N-acetyl-2-amino-8-fluoroadenine OH H CH3 O-amino acid F O 2-N-acetylaminoadenine OH H CH3 O-amino acid F O 2-N-acetylamino-8-fluoroadenine OH H CH3 O-amino acid F O 2-N-acetylamino-8-fluorohypoxanthine OH CH3 O-amino acid F 0 2-N-acetylaminohypoxanthine OH H CH3 O-amino acid Br O Thymine F H CH3 O-amino acid Br O Uracil F H CH3 O-amino acid Br 0 Guanine F H R 6 R 7 Rb X Base Rio R9 CH3 O-amino acid Br O Cytosine F H CH3 O-amino acid Br O Adenine F H CH3 0-amino acid Br O Hypoxanthine F H CH3 0-amino acid Br O 5-Fluorouracil F H CH3 O-amino acid Br O 8-Fluoroguanine F H CH3 0-amino acid Br O 5-Fluorocytosine F H CH3 O-amino acid Br O 8-Fluoroadenine F H CH3 O-amino acid Br O 2-Fluoroadenine F H CH3 O-amino acid Br O 2, 8-Difluoroadenine F H CH3 O-amino acid Br O 2-Fluorohypoxanthine F H CH3 O-amino acid Br O 8-Fluorohypoxanthine F H CH3 O-amino acid Br O 2, 8-Difluorohypoxanthine F H CH3 O-amino acid Br O 2-Aminoadenine F H CH3 O-amino acid Br O 2-Amino-8-fluoroadenine F H CH3 O-amino acid Br O 2-Amino-8-fluorohypoxanthine F H CH3 O-amino acid Br O 2-Aminohypoxanthine F H CH3 O-amino acid Br O 2-N-acetylguanine F H CH3 O-amino acid Br O 4-N-acetylcytosine F H CH3 O-amino acid Br O 6-N-acetyladenine F H CH3 O-amino acid Br O 2-N-acetyl-8-fluoroguanine F H CH3 O-amino acid Br O 4-N-acetyl-5-fluorocytosine F H CH3 O-amino acid Br O 6-N-acetyl-2-fluoroadenine F H CH3 O-amino acid Br O 6-N-acetyl-2, 8-difluoroadenine F H CH3 O-amino acid Br O 6-N-acetyl-2-aminoadenine F H CH3 O-amino acid Br O 6-N-acetyl-2-amino-8-fluoroadenine F H CH3 O-amino acid Br O 2-N-acetylaminoadenine F H CH3 O-amino acid Br O 2-N-acetylamino-8-fluoroadenine F H CH3 O-amino acid Br O 2-N-acetylamino-8-fluorohypoxanthine F H CH3 O-amino acid Br O 2-N-acetylaminohypoxanthine F H CH3 O-amino acid Br O Thymine F 0-amino acid CH3 O-amino acid Br O Uracil F O-amino acid CH3 O-amino acid Br O Guanine F O-amino acid CH3 O-amino acid Br O Cytosine F 0-amino acid CH3 O-amino acid Br O Adenine F O-amino acid CH3 O-amino acid Br O Hypoxanthine F O-amino acid CH3 O-amino acid Br O 5-Fluorouracil F 0-mino acid CH3 0-amino acid Br O 8-Fluoroguanine F O-amino acid CH3 0-amino acid Br O 5-Fluorocytosine F 0-amino acid CH3 0-amino acid Br O 8-Fluoroadenine F O-amino acid CH3 0-amino acid Br O 2-Fluoroadenine F O-amino acid CH3 O-amino acid Br O 2, 8-Difluoroadenine F O-amino acid CH3 O-amino acid Br O 2-Fluorohypoxanthine F O-amino acid CH3 O-amino acid Br O 8-Fluorohypoxanthine F O-amino acid CH3 O-amino acid Br O 2, 8-Difluorohypoxanthine F 0-amino acid CH3 O-amino acid Br O 2-Aminoadenine F O-amino acid CH3 O-amino acid Br O 2-Amino-8-fluoroadenine F O-amino acid CH3 O-amino acid Br O 2-Amino-8-fluorohypoxanthine F 0-amino acid F R7 T X Base Rlo R9 CH3 0-amino acid Br O 2-Aminohypoxanthine F 0-amino acid CH3 0-amino acid Br O 2-N-acetylguanine F O-amino acid CH3 O-amino acid Br O 4-N-acetylcytosine F O-amino acid CH3 O-amino acid Br 0 6-N-acetyladenine F O-amino acid CH3 O-amino acid Br O 2-N-acetyl-8-fluoroguanine F O-amino acid CH3 O-amino acid Br O 4-N-acetyl-5-fluorocytosine F 0-amino acid CH3 0-amino acid Br O 6-N-acetyl-2-fluoroadenine F O-amino acid CH3 O-amino acid Br O 6-N-acetyl-2, 8-difluoroadenine F O-amino acid CH3 O-amino acid Br O 6-N-acetyl-2-aminoadenine F O-amino acid CH3 O-amino acid Br O 6-N-acetyl-2-amino-8-fluoroadenine F O-amino acid CH3 O-amino acid Br O 2-N-acetylaminoadenine F O-amino acid CH3 O-amino acid Br O 2-N-acetylamino-8-fluoroadenine F O-amino acid CH3 O-amino acid Br O 2-N-acetylamino-8-fluorohypoxanthine F O-amino acid CH3 O-amino acid Br O 2-N-acetylaminohypoxanthine F O-amino acid CH3 O-amino acid Br O Thymine F O-acyl CH3 O-amino acid Br O Uracil F 0-acyl CH3 O-amino acid Br O Guanine F O-acyl CH3 O-amino acid Br O Cytosine F O-acyl CH3 O-amino acid Br O Adenine F 0-acyl CH3 O-amino acid Br O Hypoxanthine F O-acyl CH3 O-amino acid Br O 5-Fluorouracil F O-acyl CH3 O-amino acid Br O 8-Fluoroguanine F O-acyl CH3 O-amino acid Br O 5-Fluorocytosine F O-acyl CH3 0-amino acid Br O 8-Fluoroadenine F O-acyl CH3 O-amino acid Br O 2-Fluoroadenine F O-acyl CH3 O-amino acid Br O 2, 8-Difluoroadenine F 0-acyl CH3 O-amino acid Br O 2-Fluorohypoxanthine F O-acyl CH3 O-amino acid Br O 8-Fluorohypoxanthine F O-acyl CH3 0-amino acid Br O 2, 8-Difluorohypoxanthine F 0-acyl CH3 O-amino acid Br O 2-Aminoadenine F O-acyl CH3 O-amino acid Br O 2-Amino-8-fluoroadenine F 0-acyl CH3 O-amino acid Br O 2-Amino-8-fluorohypoxanthine F O-acyl CH3 O-amino acid Br O 2-Aminohypoxanthine F 0-acyl CH3 O-amino acid Br O 2-N-acetyIguanine F O-acyl CH3 O-amino acid Br O 4-N-acetylcytosine F O-acyl CH3 O-amino acid Br O 6-N-acetyladenine F O-acyl CH3 O-amino acid Br O 2-N-acetyl-8-fluoroguanine F O-acyl CH3 0-amino acid Br O 4-N-acetyl-5-fluorocytosine F O-acyl CH3 O-amino acid Br O 6-N-acetyl-2-fluoroadenine F O-acyl CH3 0-amino acid Br O 6-N-acetyl-2, 8-difluoroadenine F O-ac 1 CH3 O-amino acid Br O 6-N-acetyl-2-aminoadenine F O-acyl CH3 O-amino acid Br O 6-N-acetyl-2-amino-8-fluoroadenine F O-acyl CH3 0-amino acid Br O 2-N-acetylaminoadenine F 0-acyl CH3 O-amino acid Br O 2-N-acetylamino-8-fluoroadenine F O-acyl CH3 O-amino acid Br O 2-N-acetylamino-8-fluorohypoxanthine F O-acyl CH3 O-amino acid Br O 2-N-acetylaminohypoxanthine F O-acyl CH3 0-amino acid Br O Thymine F OH RÓ R7 T X Base--Rl° R9 CH3 O-amino acid Br O Uracil F OH CH3 O-amino acid Br O Guanine F OH CH3 O-amino acid Br O Cytosine F OH CH3 O-amino acid Br O Adenine F OH CH3 O-amino acid Br O Hypoxanthine F OH CH3 O-amino acid Br O 5-Fluorouracil F OH CH3 O-amino acid Br O 8-Fluoroguanine F OH CH3 0-amino acid Br O 5-Fluorocytosine F OH CH3 0-amino acid Br O 8-Fluoroadenine F OH CH3 0-amino acid Br O 2-Fluoroadenine F OH CH3 O-amino acid Br O 2, 8-Difluoroadenine F OH CH3 0-amino acid Br O 2-Fluorohypoxanthine F OH CH3 O-amino acid Br O 8-Fluorohypoxanthine F OH CH3 0-amino acid Br O 2, 8-Difluorohypoxanthine F OH CH3 0-amino acid Br O 2-Aminoadenine F OH CH3 0-amino acid Br O 2-Amino-8-fluoroadenine F OH CH3 0-amino acid Br O 2-Amino-8-fluorohypoxanthine F OH CH3 0-amino acid Br O 2-Aminohypoxanthine F OH CH3 O-amino acid Br O 2-N-acetylguanine F OH CH3 O-amino acid Br O 4-N-acetylcytosine F OH CH3 O-amino acid Br O 6-N-acetyladenine F OH CH3 0-amino acid Br O 2-N-acetyl-8-fluoroguanine F OH CH3 O-amino acid Br O 4-N-acetyl-5-fluorocytosine F OH CH3 0-amino acid Br O 6-N-acetyl-2-fluoroadenine F OH CH3 O-amino acid Br O 6-N-acetyl-2, 8-difluoroadenine F OH CH3 O-amino acid Br O 6-N-acety1-2-aminoadenine F OH CH3 O-amino acid Br O 6-N-acetyl-2-amino-8-fluoroadenine F OH CH3 O-amino acid Br O 2-N-acetylaminoadenine F OH CH3 0-amino acid Br O 2-N-acetylamino-8-fluoroadenine F OH CH3 O-amino acid Br O 2-N-acetylamino-8-fluorohypoxanthine F OH CH3 0-amino acid Br O 2-N-acetylaminohypoxanthine F OH CH3 O-amino acid Br O Thymine Br H CH3 O-amino acid Br O Uracil Br H CH3 O-amino acid Br O Guanine Br H CH3 O-amino acid Br O Cytosine Br H CH3 O-amino acid Br O Adenine Br H CH3 O-amino acid Br O Hypoxanthine Br H CH3 O-amino acid Br O 5-Fluorouracil Br H CH3 O-amino acid Br O 8-Fluoroguanine Br H CH3 0-amino acid Br O 5-Fluorocytosine Br H CH3 0-amino acid Br O 8-Fluoroadenine Br H CH3 0-amino acid Br O 2-Fluoroadenine Br H CH3 O-amino acid Br O 2, 8-Difluoroadenine Br H CH3 0-amino acid Br O 2-Fluorohypoxanthine Br H CH3 O-amino acid Br O 8-Fluorohypoxanthine Br H CH3 O-amino acid Br O 2, 8-Difluorohypoxanthine Br H CH3 0-amino acid Br O 2-Aminoadenine Br H R6 R7 R8 X Base Rl° R9 CH3 O-amino acid Br O 2-Amino-8-fluoroadenine Br H CH3 O-amino acid Br O 2-Amino-8-fluorohypoxanthine Br H CH3 O-amino acid Br O 2-Aminohypoxanthine Br H CH3 O-amino acid Br O 2-N-acetylguanine Br H CH3 O-amino acid Br O 4-N-acetylcytosine Br H CH3 O-amino acid Br O 6-N-denine Br H CH3 O-amino acid Br O 2-N-acetyl-8-fluoroguanine Br H CH3 O-amino acid Br O 4-N-acetyl-5-fluorocytosine Br H CH3 O-amino acid Br O 6-N-acetyl-2-fluoroadenine Br H CH3 O-amino acid Br O 6-N-acetyl-2, 8-difluoroadenine Br H CH3 O-amino acid Br O 6-N-acetyl-2-aminoadenine Br H CH3 0-amino acid Br O 6-N-acetyl-2-amino-8-fluoroadenine Br H CH3 O-amino acid Br O 2-N-acetylaminoadenine Br H CH3 O-amino acid Br O 2-N-acetylamino-8-fluoroadenine Br H CH3 O-amino acid Br O 2-N-acetylamino-8-fluorohypoxanthine Br H CH3 O-amino acid Br O 2-N-acetylaminohypoxanthine Br H CH3 O-amino acid Br O Thymine Br O-amino acid CH3 O-amino acid Br O Uracil Br O-amino acid CH3 0-amino acid Br O Guanine Br O-amino acid CH3 O-amino acid Br O Cytosine Br O-amino acid CH3 O-amino acid Br O Adenine Br O-amino acid CH3 O-amino acid Br O Hypoxanthine Br 0-amino acid CH3 O-amino acid Br O 5-Fluorouracil Br O-amino acid CH3 0-amino acid Br O 8-Fluoroguanine Br O-amino acid CH3 O-amino acid Br O 5-Fluorocytosine Br O-amino acid CH3 O-amino acid Br O 8-Fluoroadenine Br O-amino acid CH3 O-amino acid Br O 2-Fluoroadenine Br O-amino acid CH3 O-amino acid Br O 2, 8-Difluoroadenine Br O-amino acid CH3 O-amino acid Br O 2-Fluorohypoxanthine Br O-amino acid CH3 O-amino acid Br O 8-Fluorohypoxanthine Br O-amino acid CH3 0-amino acid Br O 2, 8-Difluoroh oxanthine Br O-amino acid CH3 O-amino acid Br O 2-Aminoadenine Br O-amino acid CH3 O-amino acid Br O 2-Amino-8-fluoroadenine Br O-amino acid CH3 O-amino acid Br O 2-Amino-8-fluorohypoxanthine Br 0-amino acid CH3 O-amino acid Br O 2-Aminohypoxanthine Br 0-amino acid CH3 O-amino acid Br O 2-N-acetylguanine Br O-amino acid CH3 O-amino acid Br O 4-N-acetylcytosine Br O-amino acid CH3 O-amino acid Br O 6-N-acetyladenine Br O-amino acid CH3 O-amino acid Br O 2-N-acetyl-8-fluoroguanine Br O-amino acid CH3 O-amino acid Br O 4-N-acetyl-5-fluorocytosine Br 0-amino acid CH3 O-amino acid Br O 6-N-acetyl-2-fluoroadenine Br O-amino acid CH3 0-amino acid Br O 6-N-acetyl-2, 8-difluoroadenine Br O-amino acid CH3 O-amino acid Br O 6-N-acetyl-2-aminoadenine Br O-amino acid CH3 O-amino acid Br O 6-N-acetyl-2-amino-8-fluoroadenine Br O-amino acid CH3 0-amino acid Br O 2-N-acetylaminoadenine Br O-amino acid CH3 0-amino acid Br O 2-N-acetylamino-8-fluoroadenine Br O-amino acid CH3 O-amino acid Br O 2-N-acetylamino-8-fluorohypoxanthine Br O-amino acid R 6 R 7 R8 X Base Rl° R9 CH3 O-amino acid Br O 2-N-acetylaminohypoxanthine Br O-amino acid CH3 O-amino acid Br O Thymine Br O-acyl CH3 O-amino acid Br O Uracil Br O-acyl CH3 O-amino acid Br O Guanine Br O-acyl CH3 O-amino acid Br O Cytosine Br O-acyl CH3 O-amino acid Br O Adenine Br O-acyl CH3 O-amino acid Br O Hypoxanthine Br O-acyl CH3 O-amino acid Br O 5-Fluorouracil Br O-acyl CH3 O-amino acid Br O 8-Fluoro uanine Br O-ac 1 CH3 O-amino acid Br O 5-Fluorocytosine Br O-acyl CH3 O-amino acid Br O 8-Fluoroadenine Br O-acyl CH3 O-amino acid Br O 2-Fluoroadenine Br O-acyl CH3 O-amino acid Br O 2, 8-Difluoroadenine Br O-acyI CH3 O-amino acid Br 0 2-Fluorohypoxanthine Br 0-acyl CH3 O-amino acid Br O 8-Fluorohypoxanthine Br O-acyl CH3 O-amino acid Br O 2, 8-Difluorohypoxanthine Br O-acyl CH3 O-amino acid Br O 2-Aminoadenine Br O-acyl CH3 O-amino acid Br O 2-Amino-8-fluoroadenine Br O-acyl CH3 O-amino acid Br O 2-Amino-8-fluorohypoxanthine Br O-acyl CH3 O-amino acid Br O 2-Aminohypoxanthine Br O-acyl CH3 O-amino acid Br O 2-N-acetylguanine Br O-acyl CH3 O-amino acid Br O 4-N-acetylcytosine Br O-acyl CH3 O-amino acid Br O 6-N-acetyladenine Br O-acyl CH3 O-amino acid Br O 2-N-acetyl-8-fluoroguanine Br O-acyl CH3 O-amino acid Br O 4-N-acetyl-5-fluorocytosine Br O-acyl CH3 O-amino acid Br O 6-N-acetyl-2-fluoroadenine Br O-acyl CH3 0-amino acid Br O 6-N-acetyl-2, 8-difluoroadenine Br O-acyl CH3 O-amino acid Br O 6-N-acetyl-2-aminoadenine Br O-acyl CH3 O-amino acid Br O 6-N-acetyl-2-amino-8-fluoroadenine Br O-acyl CH3 O-amino acid Br O 2-N-acetylaminoadenine Br O-acyl CH3 O-amino acid Br O 2-N-acetylamino-8-fluoroadenine Br O-ac 1 CH3 O-amino acid Br O 2-N-acetylamino-8-fluorohypoxanthine Br O-acyl CH3 O-amino acid Br O 2-N-acetylaminohypoxanthine Br O-acyl CH3 O-amino acid Br O Thymine Br OH CH3 O-amino acid Br O Uracil Br OH CH3 O-amino acid Br O Guanine Br OH CH3 O-amino acid Br O Cytosine Br OH CH3 O-amino acid Br O Adenine Br OH CH3 O-amino acid Br O Hypoxanthine Br OH CH3 O-amino acid Br O 5-Fluorouracil Br OH CH3 0-amino acid Br O 8-Fluoro uanine Br OH CH3 O-amino acid Br O 5-Fluorocytosine Br OH CH3 O-amino acid Br O 8-Fluoroadenine Br OH CH3 O-amino acid Br O 2-Fluoroadenine Br OH CH3 O-amino acid Br O 2, 8-Difluoroadenine Br OH CH3 O-amino acid Br O 2-Fluorohypoxanthine Br OH CH3 O-amino acid Br O 8-Fluorohypoxanthine Br OH F R7 F x Base R R CH3 0-amino acid Br O 2, 8-Difluorohypoxanthine Br OH CH3 O-amino acid Br O 2-Aminoadenine Br OH CH3 0-amino acid Br O 2-Amino-8-fluoroadenine Br OH CH3 O-amino acid Br O 2-Amino-8-fluorohypoxanthine Br OH CH3 O-amino acid Br O 2-Aminoh oxanthine Br OH CH3 O-amino acid Br O 2-N-acetylguanine Br OH CH3 O-amino acid Br O 4-N-acetylcytosine Br OH CH3 O-amino acid Br O 6-N-acetyladenine Br OH CH3 O-amino acid Br O 2-N-acetyl-8-fluoroguanine Br OH CH3 0-amino acid Br O 4-N-acetyl-5-fluorocytosine Br OH CH3 O-amino acid Br O 6-N-acetyl-2-fluoroadenine Br OH CH3 0-amino acid Br O 6-N-acetyl-2, 8-difluoroadenine Br OH CH3 O-amino acid Br O 6-N-acetyl-2-aminoadenine Br OH CH3 O-amino acid Br O 6-N-acetyl-2-amino-8-fluoroadenine Br OH CH3 O-amino acid Br O 2-N-acetylaminoadenine Br OH CH3 O-amino acid Br O 2-N-acetylamino-8-fluoroadenine Br OH CH3 O-amino acid Br O 2-N-acetylamino-8-fluorohypoxanthine Br OH CH3 0-amino acid Br O 2-N-acetylaminohypoxanthine Br OH CH3 O-amino acid Br O Thymine Cl H CH3 O-amino acid Br O Uracil Cl H CH3 O-amino acid Br O Guanine Cl H CH3 O-amino acid Br O Cytosine Cl H CH3 O-amino acid Br O Adenine Cl H CH3 O-amino acid Br O Hypoxanthine Cl H CH3 O-amino acid Br O 5-Fluorouracil Cl H CH3 O-amino acid Br O 8-Fluoroguanine Cl H CH3 O-amino acid Br O 5-Fluorocytosine Cl H CH3 O-amino acid Br O 8-Fluoroadenine Cl H CH3 O-amino acid Br O 2-Fluoroadenine Cl H CH3 O-amino acid Br O 2, 8-Difluoroadenine Cl H CH3 0-amino acid Br O 2-Fluorohypoxanthine Cl H CH3 O-amino acid Br O 8-Fluorohypoxanthine Cl H CH3 O-amino acid Br O 2, 8-Difluorohypoxanthine Cl H CH3 O-amino acid Br O 2-Aminoadenine Cl H CH3 O-amino acid Br O 2-Amino-8-fluoroadenine Cl H CH3 O-amino acid Br O 2-Amino-8-fluorohypoxanthine Cl H CH3 O-amino acid Br O 2-Aminohypoxanthine Cl H CH3 O-amino acid Br O 2-N-acetylguanine Cl H CH3 O-amino acid Br O 4-N-acetylcytosine Cl H CH3 O-amino acid Br O 6-N-acetyladenine Cl H CH3 O-amino acid Br O 2-N-acetyl-8-fluoroguanine Cl H CH3 O-amino acid Br O 4-N-acetyl-5-fluorocytosine Cl H CH3 O-amino acid Br O 6-N-acetyl-2-fluoroadenine Cl H CH3 O-amino acid Br O 6-N-acetyl-2, 8-difluoroadenine Cl H CH3 0-amino acid Br O 6-N-acetyl-2-aminoadenine Cl H CH3 O-amino acid Br O 6-N-acetyl-2-amino-8-fluoroadenine Cl H CH3 O-amino acid Br O 2-N-acetylaminoadenine Cl H R R R X Base R R CH3 O-amino acid Br O 2-N-acetylamino-8-fluoroadenine Cl H CH3 O-amino acid Br O 2-N-acetylamino-8-fluorohypoxanthine Cl H CH3 O-amino acid Br O 2-N-acetylaminohypoxanthine Cl H CH3 O-amino acid Br O Thymine Cl O-amino acid CH3 O-amino acid Br O Uracil Cl 0-amino acid CH3 O-amino acid Br O Guanine Cl 0-amino acid CH3 O-amino acid Br O Cytosine Cl O-amino acid CH3 O-amino acid Br O Adenine Cl 0-amino acid CH3 O-amino acid Br O Hypoxanthine Cl O-amino acid CH3 O-amino acid Br O 5-Fluorouracil Cl O-amino acid CH3 0-amino acid Br O 8-Fluoroguanine Cl O-amino acid CH3 O-amino acid Br O 5-Fluorocytosine Cl O-amino acid CH3 O-amino acid Br O 8-Fluoroadenine Cl O-amino acid CH3 0-amino acid Br O 2-Fluoroadenine Cl O-amino acid CH3 0-amino acid Br O 2, 8-Difluoroadenine Cl O-amino acid CH3 O-amino acid Br O 2-Fluorohypoxanthine Cl O-amino acid CH3 O-amino acid Br O 8-Fluorohy oxanthine Cl O-amino acid CH3 O-amino acid Br O 2, 8-Difluorohypoxanthine Cl O-amino acid CH3 O-amino acid Br O 2-Aminoadenine Cl O-amino acid CH3 O-amino acid Br O 2-Amino-8-fluoroadenine Cl O-am ino acid CH3 O-amino acid Br O 2-Amino-8-fluorohypoxanthine Cl O-amino acid CH3 O-amino acid Br O 2-Aminohy oxanthine C1 O-amino acid CH3 O-amino acid Br O 2-N-acetylguanine Cl O-amino acid CH3 O-amino acid Br O 4-N-acetylcytosine Cl O-amino acid CH3 O-amino acid Br O 6-N-acetyladenine Cl O-amino acid CH3 O-amino acid Br O 2-N-acetyl-8-fluoroguanine Cl O-amino acid CH3 O-amino acid Br O 4-N-acetyl-5-fluorocytosine Cl 0-amino acid CH3 O-amino acid Br O 6-N-acetyl-2-fluoroadenine Cl 0-amino acid CH3 O-amino acid Br O 6-N-acetyl-2, 8-difluoroadenine Cl O-amino acid CH3 O-amino acid Br O 6-N-acetyl-2-aminoadenine Cl O-amino acid CH3 O-amino acid Br O 6-N-acetyl-2-amino-8-fluoroadenine Cl 0-amino acid CH3 O-amino acid Br O 2-N-acetylaminoadenine Cl O-amino acid CH3 O-amino acid Br O 2-N-acet lamino-8-fluoroadenine CI O-amino acid CH3 O-amino acid Br O 2-N-acetylamino-8-fluorohypoxanthine CI O-amino acid CH3 O-amino acid Br O 2-N-acetylaminohypoxanthine Cl O-amino acid CH3 O-amino acid Br O Thymine Cl 0-acyl CH3 O-amino acid Br O Uracil Cl O-acyl CH3 O-amino acid Br O Guanine Cl O-acyl CH3 O-amino acid Br O Cytosine Cl O-acyl CH3 O-amino acid Br O Adenine Cl O-acyl CH3 O-amino acid Br O Hypoxanthine Cl acyl X CH3 O-amino acid Br O 5-Fluorouracil Cl 0-acyl CH3 O-amino acid Br O 8-Fluoroguanine Cl O-acyl CH3 O-amino acid Br O 5-Fluorocytosine Cl O-acyl CH3 0-amino acid Br O 8-Fluoroadenine Cl O-acyl CH3 O-amino acid Br O 2-Fluoroadenine Cl O-ac 1 CH3 O-amino acid Br O 2, 8-Difluoroadenine Cl O-acyl R6 R'R8 X Base R R' CH3 0-amino acid Br O 2-Fluorohypoxanthine Cl O-acyl CH3 O-amino acid Br O 8-Fluorohypoxanthine Cl O-acyl CH3 0-amino acid Br O 2, 8-Difluorohypoxanthine Cl O-acyl CH3 0-amino acid Br O 2-Aminoadenine CI O-acyl CH3 O-amino acid Br O 2-Amino-8-fluoroadenine Cl O-acyl CH3 O-amino acid Br O 2-Amino-8-fluorohypoxanthine Cl O-acyl CH3 O-amino acid Br O 2-Aminohypoxanthine Cl O-acyl CH3 0-amino acid Br O 2-N-acetylguanine Cl O-acyl CH3 O-amino acid Br O 4-N-acet lcytosine Cl O-ac 1 CH3 O-amino acid Br O 6-N-acetyladenine Cl O-acYI # CH3 O-amino acid Br O 2-N-acetyl-8-fluoroguanine Cl O-acyl CH3 O-amino acid Br O 4-N-acetyl-5-fluorocytosine Cl O-acyl CH3 O-amino acid Br O 6-N-acetyl-2-fluoroadenine Cl O-acyl CH3 0-amino acid Br O 6-N-acetyl-2, 8-difluoroadenine Cl O-acyl CH3 O-amino acid Br O 6-N-acetyl-2-aminoadenine Cl O-acyl CH3 O-amino acid Br O 6-N-acetyl-2-amino-8-fluoroadenine Cl O-acy1 f CH3 0-amino acid Br O 2-N-acetylaminoadenine Cl 0-acyl CH3 O-amino acid Br O 2-N-acetylam ino-8-fluoroadenine Cl O-acyl CH3 O-amino acid Br O 2-N-acet lamino-8-fluorohy oxanthine Cl O-ac 1 f. f CH3 O-amino acid Br O 2-N-acetylaminohypoxanthine Cl O-acyl CH3 O-amino acid Br O Thymine Cl OH CH3 O-amino acid Br O Uracil Cl OH CH3 O-amino acid Br O Guanine Cl OH CH3 O-amino acid Br O Cytosine Cl OH CH3 O-amino acid Br O Adenine Cl OH CH3 O-amino acid Br O Hypoxanthine Cl OH CH3 O-amino acid Br O 5-Fluorouracil Cl OH CH3 O-amino acid Br O 8-Fluoroguanine Cl OH CH3 O-amino acid Br O 5-Fluorocytosine Cl OH CH3 O-amino acid Br O 8-Fluoroadenine Cl OH CH3 O-amino acid Br O 2-Fluoroadenine Cl OH CH3 O-amino acid Br O 2, 8-Difluoroadenine Cl OH CH3 O-amino acid Br O 2-Fluorohypoxanthine Cl OH CH3 O-amino acid Br O 8-Fluorohy oxanthine CI OH CH3 O-amino acid Br O 2, 8-Difluorohypoxanthine Cl OH CH3 O-amino acid Br O 2-Aminoadenine Cl OH CH3 0-amino acid Br O 2-Amino-8-fluoroadenine Cl OH CH3 0-amino acid Br O 2-Amino-8-fluorohypoxanthine Cl OH CH3 0-amino acid Br O 2-Aminohypoxanthine Cl OH CH3 O-amino acid Br O 2-N-acetylguanine Cl OH CH3 O-amino acid Br O 4-N-acetylcytosine Cl OH CH3 O-amino acid Br O 6-N-acetyladenine Cl OH CH3 O-amino acid Br O 2-N-acetyl-8-fluoroguanine Cl OH CH3 O-amino acid Br O 4-N-acetyl-5-fluorocytosine Cl OH CH3 0-amino acid Br O 6-N-acetyl-2-fluoroadenine Cl OH CH3 O-amino acid Br O 6-N-acetyl-2, 8-difluoroadenine Cl OH CH3 O-amino acid Br O 6-N-acetyl-2-aminoadenine Cl OH R6 R'w X Base Rl° R9 CH3 O-amino acid Br O 6-N-acetyl-2-amino-8-fluoroadenine Cl OH CH3 O-amino acid Br O 2-N-acetylaminoadenine Cl OH CH3 O-amino acid Br O 2-N-acetylamino-8-fluoroadenine Cl OH CH3 O-amino acid Br O 2-N-acetylamino-8-fluorohypoxanthine Cl OH CH3 O-amino acid Br O 2-N-acetylaminohypoxanthine Cl OH CH3 O-amino acid Br O Thymine H H CH3 O-amino acid Br O Uracil H H CH3 O-amino acid Br O Guanine H H CH3 0-amino acid Br O Cytosine H H CH3 0-amino acid Br O Adenine H H CH3 O-amino acid Br O Hypoxanthine H H CH3 O-amino acid Br O 5-Fluorouracil H H CH3 O-amino acid Br O 8-Fluoroguanine H H CH3 O-amino acid Br O 5-Fluorocytosine H H CH3 O-amino acid Br O 8-Fluoroadenine H H CH3 0-amino acid Br O 2-Fluoroadenine H H CH3 O-amino acid Br O 2, 8-Difluoroadenine H H CH3 O-amino acid Br O 2-Fluorohypoxanthine H H CH3 O-amino acid Br O 8-Fluorohypoxanthine H H CH3 O-amino acid Br O 2, 8-Difluorohypoxanthine H H CH3 O-amino acid Br O 2-Aminoadenine H H CH3 O-amino acid Br O 2-Amino-8-fluoroadenine H H CH3 O-amino acid Br O 2-Amino-8-fluorohypoxanthine H H CH3 O-amino acid Br O 2-Aminohypoxanthine H H CH3 O-amino acid Br O 2-N-acetylguanine H H CH3 O-amino acid Br O 4-N-acetylcytosine H H CH3 O-amino acid Br O 6-N-acetyladenine H H CH3 O-amino acid Br O 2-N-acetyl-8-fluoroguanine H H CH3 O-amino acid Br O 4-N-acetyl-5-fluorocytosine H H CH3 O-amino acid Br O 6-N-acetyl-2-fluoroadenine H H CH3 O-amino acid Br O 6-N-acetyl-2, 8-difluoroadenine H H CH3 O-amino acid Br O 6-N-acetyl-2-aminoadenine H H CH3 O-amino acid Br O 6-N-acetyl-2-amino-8-fluoroadenine H H CH3 O-amino acid Br O 2-N-acetylaminoadenine H H CH3 O-amino acid Br O 2-N-acetylamino-8-fluoroadenine H H CH3 O-amino acid Br O 2-N-acetylamino-8-fluorohypoxanthine H H CH3 O-amino acid Br O 2-N-acetylaminohypoxanthine H H CH3 O-amino acid Br O Thymine H O-amino acid CH3 O-amino acid Br O Uracil H O-amino acid CH3 O-amino acid Br O Guanine H O-amino acid CH3 O-amino acid Br O Cytosine H O-amino acid CH3 O-amino acid Br O Adenine H O-amino acid CH3 O-amino acid Br O Hypoxanthine H O-amino acid CH3 O-amino acid Br O 5-Fluorouracil H O-amino acid CH3 O-amino acid Br O 8-Fluoroguanine H O-amino acid CH3 O-amino acid Br O 5-Fluorocytosine H O-amino acid CH3 O-amino acid Br O 8-Fluoroadenine H O-amino acid R'W X Base z R CH3 O-amino acid Br O 2-Fluoroadenine H O-amino acid CH3 O-amino acid Br O 2, 8-Difluoroadenine H O-amino acid CH3 O-amino acid Br O 2-Fluorohypoxanthine H O-amino acid CH3 O-amino acid Br O 8-Fluorohypoxanthine H O-amino acid CH3 O-amino acid Br O 2, 8-Difluorohypoxanthine H 0-amino acid CH3 O-amino acid Br O 2-Aminoadenine H O-amino acid CH3 0-amino acid Br O 2-Amino-8-fluoroadenine H O-amino acid CH3 O-amino acid Br O 2-Amino-8-fluorohypoxanthine H O-amino acid CH3 0-amino acid Br O 2-Aminohypoxanthine H 0-amino acid CH3 0-amino acid Br O 2-N-acetylguanine H O-amino acid CH3 O-amino acid Br O 4-N-acetylcytosine H 0-amino acid CH3 0-amino acid Br O 6-N-acetyladenine H O-amino acid CH3 0-amino acid Br O 2-N-acetyl-8-fluoroguanine H O-amino acid CH3 0-amino acid Br O 4-N-acetyl-5-fluorocytosine H O-amino acid CH3 0-amino acid Br O 6-N-acetyl-2-fluoroadenine H O-amino acid CH3 0-amino acid Br O 6-N-acetyl-2, 8-difluoroadenine H O-amino acid CH3 O-amino acid Br O 6-N-acetyl-2-aminoadenine H O-amino acid CH3 0-amino acid Br O 6-N-acetyl-2-amino-8-fluoroadenine H O-amino acid CH3 0-amino acid Br O 2-N-acetylaminoadenine H O-amino acid CH3 O-amino acid Br O 2-N-acetylamino-8-fluoroadenine H O-amino acid CH3 0-amino acid Br O 2-N-acetylamino-8-fluorohypoxanthine H O-amino acid CH3 0-amino acid Br O 2-N-acetylaminohypoxanthine H O-amino acid CH3 0-amino acid Br O Thymine H O-acyl CH3 0-amino acid Br O Uracil H O-acyl CH3 0-amino acid Br O Guanine H 0-acyl CH3 0-amino acid Br O Cytosine H 0-acyl CH3 O-amino acid Br O Adenine H 0-acyl CH3 0-amino acid Br O Hypoxanthine H 0-acyl CH3 O-amino acid Br O 5-Fluorouracil 0-acyl CH3 0-amino acid Br 0 8-Fluoroguanine H 0-acyl CH3 0-amino acid Br O 5-Fluorocytosine H 0-acyl CH3 0-amino acid Br O 8-Fluoroadenine H O-acyl CH3 O-amino acid Br O 2-Fluoroadenine H 0-acyl CH3 O-amino acid Br O 2, 8-Difluoroadenine H 0-acyl CH3 O-amino acid Br O 2-Fluorohypoxanthine H 0-acyl CH3 O-amino acid Br O 8-Fluorohypoxanthine H O-acyl CH3 0-amino acid Br O 2, 8-Difluorohypoxanthine H 0-acyl CH3 0-amino acid Br O 2-Aminoadenine H 0-acyl CH3 0-amino acid Br O 2-Amino-8-fluoroadenine H O-acyl CH3 0-amino acid Br O 2-Amino-8-fluorohypoxanthine H O-acyl CH3 0-amino acid Br O 2-Aminohypoxanthine H O-acyl CH3 0-amino acid Br O 2-N-acetylguanine H O-acyl CH3 O-amino acid Br O 4-N-acetylcytosine H O-acyl CH3 O-amino acid Br O 6-N-acetyladenine H O-acyl f CH3 O-amino acid Br O 2-N-acetyl-8-fluoroguanine H 0-acyl CH3 0-amino acid Br O 4-N-acetyl-5-fluorocytosine H 0-acyl CH3 O-amino acid Br O 6-N-acet I-2-fluoroadenine H O-ac 1 R R'R X Base R R CH3 O-amino acid Br O 6-N-acetyl-2, 8-difluoroadenine H 0-acyl CH3 O-amino acid Br O 6-N-acetyl-2-aminoadenine H O-acyl CH3 O-amino acid Br O 6-N-acetyl-2-amino-8-fluoroadenine H O-acyl CH3 O-amino acid Br O 2-N-acetylaminoadenine H O-acyl CH3 0-amino acid Br O 2-N-acetylamino-8-fluoroadenine H 0-acyl CH3 0-amino acid Br 0 2-N-acetylamino-8-fluorohypoxanthine H 0-acyl CH3 O-amino acid Br O 2-N-acetylaminohypoxanthine H O-acyl CH3 O-amino acid Br O Thymine H OH CH3 O-amino acid Br O Uracil H OH CH3 O-amino acid Br O Guanine H OH CH3 O-amino acid Br O Cytosine H OH CH3 O-amino acid Br O Adenine H OH CH3 O-amino acid Br O Hypoxanthine H OH CH3 O-amino acid Br O 5-Fluorouracil H OH CH3 O-amino acid Br O 8-Fluoroguanine H OH CH3 0-amino acid Br O 5-Fluorocytosine H OH CH3 O-amino acid Br O 8-Fluoroadenine H OH CH3 0-amino acid Br O 2-Fluoroadenine H OH CH3 O-amino acid Br O 2, 8-Difluoroadenine H OH CH3 O-amino acid Br O 2-Fluorohypoxanthine H OH CH3 0-amino acid Br O 8-Fluorohy oxanthine H OH CH3 O-amino acid Br O 2, 8-Difluorohypoxanthine H OH CH3 O-amino acid Br O 2-Aminoadenine H OH CH3 O-amino acid Br O 2-Amino-8-fluoroadenine H OH CH3 O-amino acid Br O 2-Amino-8-fluorohypoxanthine H OH CH3 0-amino acid Br O 2-Aminohypoxanthine H OH CH3 O-amino acid Br O 2-N-acetylguanine H OH CH3 O-amino acid Br O 4-N-acetylcytosine H OH CH3 O-amino acid Br O 6-N-acetyladenine H OH CH3 O-amino acid Br O 2-N-acetyl-8-fluoroguanine H OH CH3 0-amino acid Br O 4-N-acetyl-5-fluorocytosine H OH CH3 O-amino acid Br O 6-N-acetyl-2-fluoroadenine H OH CH3 O-amino acid Br O 6-N-acetyl-2, 8-difluoroadenine H OH CH3 0-amino acid Br O 6-N-acetyl-2-aminoadenine H OH CH3 O-amino acid Br O 6-N-acetyl-2-amino-8-fluoroadenine H OH CH3 O-amino acid Br O 2-N-acetylaminoadenine H OH CH3 O-amino acid Br O 2-N-acetylamino-8-fluoroadenine H OH CH3 O-amino acid Br O 2-N-acetylamino-8-fluorohypoxanthine H OH CH3 0-amino acid Br O 2-N-acetylaminohypoxanthine H OH CH3 O-amino acid Br O Thymine OH H CH3 O-amino acid Br O Uracil OH CH3 0-amino acid Br O Guanine OH H CH3 O-amino acid Br O Cytosine OH H CH3 O-amino acid Br O Adenine OH H CH3 O-amino acid Br O Hypoxanthine OH H CH3 O-amino acid Br O 5-Fluorouracil OH H CH3 0-amino acid Br O 8-Fluoroguanine OH H F R7 F X Base l Rl° R9 CH3 O-amino acid Br O 5-Fluorocytosine OH H CH3 O-amino acid Br O 8-Fluoroadenine OH H CH3 0-amino acid Br O 2-Fluoroadenine OH H CH3 O-amino acid Br O 2, 8-Difluoroadenine OH H CH3 O-amino acid Br O 2-Fluorohypoxanthine OH H CH3 O-amino acid Br O 8-Fluorohypoxanthine OH H CH3 O-amino acid Br O 2, 8-Difluorohypoxanthine OH H CH3 O-amino acid Br O 2-Aminoadenine OH H CH3 O-amino acid Br O 2-Amino-8-fluoroadenine OH H CH3 O-amino acid Br O 2-Amino-8-fluorohypoxanthine OH H CH3 O-amino acid Br O 2-Aminohypoxanthine OH H CH3 O-amino acid Br O 2-N-acetylguanine OH H CH3 0-amino acid Br O 4-N-acetylc osine OH H CH3 O-amino acid Br O 6-N-acetyladenine OH H CH3 O-amino acid Br O 2-N-acetyl-8-fluoroguanine OH H CH3 O-amino acid Br O 4-N-acetyl-5-fluorocytosine OH H CH3 O-amino acid Br O 6-N-acetyl-2-fluoroadenine OH H CH3 O-amino acid Br O 6-N-acetyl-2, 8-difluoroadenine OH H CH3 O-amino acid Br O 6-N-acetyl-2-aminoadenine OH H CH3 O-amino acid Br O 6-N-acetyl-2-amino-8-fluoroadenine OH H CH3 0-amino acid Br O 2-N-acetylaminoadenine OH H CH3 O-amino acid Br O 2-N-acetylamino-8-fluoroadenine OH H CH3 O-amino acid Br O 2-N-acetylamino-8-fluorohypoxanthine OH H CH3 O-amino acid Br O 2-N-acetylaminohypoxanthine OH H CH3 O-amino acid Cl O Thymine F H CH3 O-amino acid Cl O Uracil F H CH3 O-amino acid Cl O Guanine F H CH3 0-amino acid Cl 0 Cytosine F H CH3 0-amino acid Cl O Adenine F H CH3 0-amino acid Cl O Hypoxanthine F H #s CH3 O-amino acid Cl O 5-Fluorouracil F H CH3 O-amino acid Cl O 8-Fluoroguanine F H CH3 O-amino acid Cl O 5-Fluorocytosine F H CH3 O-amino acid Cl O 8-Fluoroadenine F H CH3 O-amino acid Cl O 2-Fluoroadenine F H CH3 O-amino acid Cl O 2, 8-Difluoroadenine F H CH3 0-amino acid Cl 0 2-Fluorohypoxanthine F H CH3 0-amino acid Cl O 8-Fluorohypoxanthine F H CH3 O-amino acid Cl O 2, 8-Difluorohypoxanthine F H CH3 O-amino acid Cl O 2-Aminoadenine F H CH3 O-amino acid Cl O 2-Amino-8-fluoroadenine F H CH3 O-amino acid Cl O 2-Amino-8-fluorohypoxanthine F H CH3 0-amino acid Cl O 2-Aminohypoxanthine F H CH3 O-amino acid Cl O 2-N-acetylguanine F H CH3 O-amino acid Cl O-N-acetylcYtosine F H CH3 O-amino acid Cl 0 6-N-acetyladenine F H CH3 O-amino acid Cl O 2-N-acetyl-8-fluoroguanine F H R R R X Base R R CH3 O-amino acid Cl O 4-N-acetyl-5-fluorocytosine F H CH3 O-amino acid Cl O 6-N-acetyl-2-fluoroadenine F H CH3 0-amino acid Cl O 6-N-acetyl-2, 8-difluoroadenine F H CH3 O-amino acid Cl O 6-N-acetyl-2-aminoadenine F H CH3 0-amino acid Cl O 6-N-acetyl-2-amino-8-fluoroadenine F H CH3 O-amino acid Cl O 2-N-acet laminoadenine F H CH3 0-amino acid Cl 0 2-N-acetylamino-8-fluoroadenine F H CH3 O-amino acid Cl O 2-N-acetylamino-8-fluorohypoxanthine F H CH3 O-amino acid Cl O 2-N-acetylaminohypoxanthine F H CH3 0-amino acid Cl O Thymine F O-amino acid CH3 O-amino acid Cl O Uracil F O-amino acid CH3 O-amino acid Cl O Guanine F O-amino acid CH3 O-amino acid Cl O Cytosine F O-amino acid CH3 O-amino acid Cl O Adenine F O-amino acid CH3 O-amino acid Cl O Hypoxanthine F 0-amino acid CH3 0-amino acid Cl O 5-Fluorouracil F O-amino acid CH3 O-amino acid Cl O 8-Fluoroguanine F O-amino acid CH3 O-amino acid Cl O 5-Fluorocytosine F O-amino acid CH3 O-amino acid Cl O 8-Fluoroadenine F O-amino acid CH3 O-amino acid Cl O 2-Fluoroadenine F O-amino acid CH3 0-amino acid Cl 0 2, 8-Difluoroadenine F O-amino acid CH3 O-amino acid Cl O 2-Fluorohypoxanthine F O-amino acid CH3 0-amino acid Cl O 8-Fluorohypoxanthine F O-amino acid CH3 0-amino acid C1 O 2, 8-Difluorohy oxanthine F O-amino acid CH3 O-amino acid Cl O 2-Aminoadenine F O-amino acid CH3 O-amino acid Cl O 2-Amino-8-fluoroadenine F O-amino acid CH3 O-amino acid Cl O 2-Amino-8-fluorohypoxanthine F O-amino acid CH3 O-amino acid Cl O 2-Aminohypoxanthine F O-amino acid CH3 O-amino acid Cl O 2-N-acetylguanine F 0-amino acid CH3 O-amino acid Cl O 4-N-acetylcytosine F O-amino acid CH3 O-amino acid Cl 0 6-N-acetyladenine F 0-amino acid CH3 O-amino acid Cl 0 2-N-acetyl-8-fluoroguanine F 0-amino acid CH3 O-amino acid Cl O 4-N-acetyl-5-fluorocytosine F O-amino acid CH3 O-amino acid Cl O 6-N-acet 1-2-fluoroadenine F O-amino acid CH3 O-amino acid Cl O 6-N-acetyl-2, 8-difluoroadenine F O-amino acid CH3 O-amino acid Cl O 6-N-acetyl-2-aminoadenine F O-amino acid CH3 O-amino acid Cl O 6-N-acetyl-2-amino-8-fluoroadenine F O-amino acid CH3 O-amino acid Cl O 2-N-acetylaminoadenine F O-amino acid CH3 O-amino acid Cl O 2-N-acetylamino-8-fluoroadenine F O-amino acid CH3 O-amino acid Cl O 2-N-acetylamino-8-fluorohypoxanthine F O-amino acid CH3 0-amino acid Cl O 2-N-acetylaminohy oxanthine F O-amino acid CH3 O-amino acid Cl O Thymine F O-acyl CH3 0-amino acid Cl O Uracil F O-acyl CH3 O-amino acid Cl O Guanine F O-acy1 CH3 O-amino acid Cl O Cytosine F O-acyl CH3 O-amino acid Cl O Adenine F O-acyl CH3 O-amino acid Cl O Hypoxanthine F O-acyl R7 w X Base Rl° R9 CH3 O-amino acid Cl O 5-Fluorouracil F O-acyl CH3 O-amino acid Cl O 8-Fluoroguanine F O-acyl CH3 0-amino acid Cl O 5-Fluorocytosine F O-acyl CH3 O-amino acid Cl O 8-Fluoroadenine F O-acyl CH3 0-amino acid Cl O 2-Fluoroadenine F O-acy1 CH3 0-amino acid Cl O 2, 8-Difluoroadenine F O-acyl CH3 0-amino acid Cl O 2-Fluoroh oxanthine F O-ac 1 CH3 0-amino acid Cl O 8-Fluorohypoxanthine F O-acyl CH3 0-amino acid Cl O 2, 8-Difluorohypoxanthine _ F O-acyl CH3 0-amino acid Cl O 2-Aminoadenine F O-acyl CH3 0-amino acid Cl O 2-Amino-8-fluoroadenine F O-ac 1 CH3 O-amino acid Cl O 2-Amino-8-fluorohypoxanthine F O-acyl CH3 0-amino acid Cl O 2-Aminohypoxanthine F O-acyl CH3 0-amino acid Cl O 2-N-acetylguanine F O-acy1 CH3 0-amino acid Cl O 4-N-acetylcytosine F 0-acyl CH3 0-amino acid Cl O 6-N-acetyladenine F O-acyl CH3 O-amino acid Cl O 2-N-acetyl-8-fluoroguanine F O-acyl CH3 O-amino acid Cl O 4-N-acetyl-5-fluorocytosine F O-acyl CH3 O-amino acid Cl O 6-N-acetyl-2-fluoroadenine F O-acyl CH3 O-amino acid Cl O 6-N-acetyl-2, 8-difluoroadenine F O-acyl CH3 0-amino acid CI O 6-N-acetyl-2-aminoadenine F O-acyl CH3 O-amino acid Cl O 6-N-acetyl-2-amino-8-fluoroadenine F O-acyl CH3 O-amino acid Cl O 2-N-acetylaminoadenine F O-acyl CH3 0-amino acid Cl O 2-N-acetylamino-8-fluoroadenine F O-acyl CH3 O-amino acid Cl O 2-N-acetylamino-8-fluorohypoxanthine F O-ac CH3 0-amino acid Cl O 2-N-acetylaminohypoxanthine F O-ac CH3 O-amino acid Cl O Thymine F OH CH3 O-amino acid Cl O Uracil F OH CH3 O-amino acid Cl O Guanine F OH CH3 O-amino acid Cl O Cytosine F OH CH3 O-amino acid Cl O Adenine F OH CH3 O-amino acid Cl O Hypoxanthine F OH CH3 O-amino acid Cl O 5-Fluorouracil F OH CH3 O-amino acid Cl O 8-Fluoroguanine F OH CH3 0-amino acid Cl O 5-Fluorocytosine F OH CH3 O-amino acid Cl O 8-Fluoroadenine F OH CH3 O-amino acid Cl O 2-Fluoroadenine F OH CH3 O-amino acid Cl O 2, 8-Difluoroadenine F OH CH3 O-amino acid Cl O 2-Fluorohypoxanthine F OH CH3 0-amino acid Cl O 8-Fluorohypoxanthine F OH CH3 O-amino acid Cl O 2, 8-Difluorohypoxanthine F OH CH3 O-amino acid Cl O 2-Aminoadenine F OH CH3 O-amino acid Cl O 2-Amino-8-fluoroadenine F OH CH3 O-amino acid Cl O 2-Amino-8-fluorohypoxanthine F OH CH3 0-amino acid Cl O 2-Aminoh oxanthine F OH CH3 0-amino acid Cl O 2-N-acetyiguanine F OH CH3 0-aminoacid Ct 0 4-N-acetyIcytosineOH R6 R7 R8 X Base Rl° R9 CH3 0-amino acid Cl 0 6-N-acetyladenine F OH CH3 O-amino acid Cl O 2-N-acetyl-8-fluoroguanine F OH CH3 O-amino acid Cl O 4-N-acetyl-5-fluorocytosine F OH CH3 O-amino acid Cl O 6-N-acetyl-2-fluoroadenine F OH CH3 O-amino acid Cl O 6-N-acetyl-2, 8-difluoroadenine F OH CH3 O-amino acid Cl O 6-N-acetyl-2-aminoadenine F OH CH3 O-amino acid Cl O 6-N-acetyl-2-amino-8-fluoroadenine F OH CH3 O-amino acid Cl 0 2-N-acetylaminoadenine F OH CH3 O-amino acid Cl O 2-N-acetylamino-8-fluoroadenine F OH CH3 O-amino acid Cl O 2-N-acetylamino-8-fluorohypoxanthine F OH J f s CH3 O-amino acid Cl O 2-N-acetylaminohypoxanthine F OH CH3 O-amino acid Cl O Thymine Br H CH3 O-amino acid Cl 0 Uracil Br H CH3 O-amino acid Cl O Guanine Br H CH3 O-amino acid Cl O Cytosine Br H CH3 O-amino acid Cl O Adenine Br H CH3 O-amino acid Cl O Hypoxanthine Br H CH3 0-amino acid Cl O 5-Fluorouracil Br H CH3 0-amino acid Cl O 8-Fluoroguanine Br H CH3 O-amino acid Cl O 5-Fluorocytosine Br H CH3 O-amino acid Cl O 8-Fluoroadenine Br H CH3 O-amino acid Cl O 2-Fluoroadenine Br H CH3 O-amino acid Cl O 2, 8-Difluoroadenine Br H CH3 O-amino acid CI O 2-Fluorohy oxanthine Br H CH3 O-amino acid Cl O 8-Fluorohypoxanthine Br H CH3 0-amino acid Cl 0 2, 8-Difluorohypoxanthine Br H CH3 0-amino acid Cl O 2-Aminoadenine Br H CH3 O-amino acid Cl O 2-Amino-8-fluoroadenine Br H CH3 O-amino acid Cl O 2-Amino-8-fluorohypoxanthine Br H CH3 O-amino acid C1 O 2-Aminohy oxanthine Br H CH3 O-amino acid Cl O 2-N-acetylguanine Br H CH3 0-amino acid Cl 0 4-N-acetylcytosine Br H CH3 O-amino acid CI O 6-N-acet ladenine Br H CH3 O-amino acid Cl O 2-N-acetyl-8-fluoroguanine Br H CH3 O-amino acid Cl O 4-N-acetyl-5-fluorocytosine Br H CH3 0-amino acid Cl O 6-N-acetyl-2-fluoroadenine Br H CH3 O-amino acid Cl O 6-N-acet 1-2, 8-difluoroadenine Br H CH3 0-amino acid Cl O 6-N-acetyl-2-aminoadenine Br H CH3 O-amino acid Cl 0 6-N-acetyl-2-amino-8-fluoroadenine Br H CH3 O-amino acid C1 O 2-N-acet laminoadenine Br H CH3 O-amino acid Cl O 2-N-acetylamino-8-fluoroadenine Br H CH3 O-amino acid Cl O 2-N-acetylamino-8-fluorohypoxanthine Br H CH3 O-amino acid Cl O 2-N-acetylaminohypoxanthine Br H CH3 O-amino acid Cl O Thymine Br O-amino acid CH3 O-amino acid Cl O Uracil Br O-amino acid CH3 O-amino acid Cl O Guanine Br O-amino acid CH3 O-amino acid Cl O Cytosine Br O-amino acid R R R X Base R R CH3 O-amino acid Cl O Adenine Br O-amino acid CH3 O-amino acid Cl O Hypoxanthine Br O-amino acid CH3 O-amino acid Cl O 5-Fluorouracil Br O-amino acid CH3 O-amino acid Cl O 8-Fluoroguanine Br O-amino acid CH3 O-amino acid Cl O 5-Fluorocytosine Br O-amino acid CH3 0-amino acid Cl O 8-Fluoroadenine Br O-amino acid CH3 O-amino acid Cl O 2-Fluoroadenine Br O-amino acid CH3 O-amino acid Cl O 2, 8-Difluoroadenine Br O-amino acid CH3 0-amino acid Cl O 2-Fluorohypoxanthine Br O-amino acid CH3 O-amino acid Cl O 8-Fluorohypoxanthine Br O-amino acid CH3 O-amino acid Cl O 2, 8-Difluorohypoxanthine Br 0-amino acid CH3 O-amino acid Cl O 2-Aminoadenine Br O-amino acid CH3 O-amino acid Cl O 2-Amino-8-fluoroadenine Br O-amino acid CH3 O-amino acid Cl O 2-Amino-8-fluorohypoxanthine Br O-amino acid CH3 O-amino acid Cl O 2-Aminohypoxanthine Br O-amino acid CH3 O-amino acid Cl O 2-N-acetylguanine Br O-amino acid CH3 O-amino acid Cl O 4-N-acetylcytosine Br O-amino acid CH3 0-amino acid Cl 0 6-N-acetyladenine Br 0-amino acid CH3 O-amino acid Cl O 2-N-acetyl-8-fluoroguanine Br O-amino acid CH3 O-amino acid Cl O 4-N-acetyl-5-fluorocytosine Br O-amino acid CH3 O-amino acid Cl O 6-N-acetyl-2-fluoroadenine Br O-amino acid CH3 O-amino acid Cl O 6-N-acetyl-2, 8-difluoroadenine Br O-amino acid CH3 O-amino acid Cl O 6-N-acetyl-2-aminoadenine Br O-amino acid CH3 O-amino acid Cl O 6-N-acetyl-2-amino-8-fluoroadenine Br 0-amino acid CH3 O-amino acid C1 O 2-N-acet laminoadenine Br O-amino acid CH3 O-amino acid Cl O 2-N-acetylamino-8-fluoroadenine Br O-amino acid CH3 O-amino acid Cl O 2-N-acetylamino-8-fluorohypoxanthine Br O-amino acid CH3 0-amino acid Cl O 2-N-acetylaminohypoxanthine Br O-amino acid CH3 O-amino acid Cl O Thymine Br O-acyl CH3 O-amino acid Cl O Uracil Br O-acyl CH3 O-amino acid Cl O Guanine Br O-acyl CH3 O-amino acid Cl O Cytosine Br O-acyl CH3 0-amino acid Cl 0 Adenine Br 0-acyl CH3 O-amino acid Cl O Hypoxanthine Br O-acyl CH3 O-amino acid Cl O 5-Fluorouracil Br O-acyl CH3 O-amino acid Cl O 8-Fluoroguanine Br O-acyl CH3 O-amino acid Cl O 5-Fluorocytosine Br O-acyl CH3 O-amino acid Cl O 8-Fluoroadenine Br O-acyl CH3 O-amino acid Cl O 2-Fluoroadenine Br O-ac 1 CH3 0-amino acid Cl 0 2, 8-Difluoroadenine Br O-acyl CH3 O-amino acid CI O 2-Fluoroh oxanthine Br O-acyl CH3 O-amino acid Cl O 8-Fluorohypoxanthine Br O-acyl CH3 O-amino acid Cl O 2, 8-Difluorohypoxanthine Br O-acyl CH3 0-amino acid Cl O 2-Aminoadenine Br O-acyl CH3 O-amino acid Cl O 2-Amino-8-fluoroadenine Br O-acyl CH3 O-amino acid Cl O 2-Amino-8-fluorohypoxanthine Br O-acyl CH3 O-amino acid Cl O 2-Aminohypoxanthine Br O-acyl R6 R R X Base R R CH3 0-amino acid Cl 0 2-N-acetylguanine Br 0-acyl CH3 O-amino acid Cl O 4-N-acetylcytosine ç CH3 0-amino acid Cl 0 6-N-acetyladenine Br 0-acyl CH3 O-amino acid Cl O 2-N-acetyl-8-fluoroguanine Br O-acyI CH3 O-amino acid Cl O 4-N-acetyl-5-fluorocYtosine Br O-acyI CH3 O-amino acid Cl O 6-N-acetyl-2-fluoroadenine Br O-acyl CH3 0-amino acid Cl O 6-N-acetyl-2, 8-difluoroadenine Br O-acyl CH3 O-amino acid Cl O 6-N-acetyl-2-aminoadenine Br O-ac I CH3 O-amino acid Cl O 6-N-acetyl-2-amino-8-fluoroadenine Br O-acyl CH3 0-amino acid Cl O 2-N-acetylaminoadenine Br O-acyl CH3 O-amino acid Cl O 2-N-acetylamino-8-fluoroadenine Br 0-acyl CH3 O-amino acid Cl O 2-N-acetylamino-8-fluorohypoxanthine Br O-acyl CH3 O-amino acid Cl O 2-N-acetylaminohypoxanthine Br O-acyl CH3 0-amino acid Cl 0 Thymine Br OH CH3 O-amino acid Cl O Uracil Br OH CH3 0-amino acid Cl 0 Guanine Br OH CH3 O-amino acid Cl O Cytosine Br OH CH3 O-amino acid Cl O Adenine Br OH CH3 O-amino acid Cl O Hypoxanthine Br OH CH3 O-amino acid Cl O 5-Fluorouracil Br OH CH3 0-amino acid Cl 0 8-Fluoroguanine Br OH CH3 O-amino acid Cl O 5-Fluorocytosine Br OH CH3 O-amino acid Cl O 8-Fluoroadenine Br OH CH3 O-amino acid Cl O 2-Fluoroadenine Br OH CH3 O-amino acid Cl O 2, 8-Difluoroadenine Br OH CH3 O-amino acid Cl O 2-Fluorohypoxanthine Br OH CH3 O-amino acid Cl O 8-Fluorohypoxanthine Br OH CH3 O-amino acid Cl O 2, 8-Difluorohypoxanthine Br OH CH3 0-amino acid Cl O 2-Aminoadenine Br OH CH3 O-amino acid Cl O 2-Amino-8-fluoroadenine Br OH CH3 O-amino acid Cl O 2-Amino-8-fluorohypoxanthine Br OH CH3 O-amino acid Cl O 2-Aminohypoxanthine Br OH CH3 O-amino acid Cl O 2-N-acetylguanine Br OH CH3 O-amino acid Cl O 4-N-acetylcytosine Br OH CH3 O-amino acid Cl O 6-N-acetyladenine Br OH CH3 O-amino acid Cl O 2-N-acetyl-8-fluoroguanine Br OH CH3 O-amino acid Cl O 4-N-acetyl-5-fluorocytosine Br OH CH3 0-amino acid Cl O 6-N-acetyl-2-fluoroadenine Br OH CH3 O-amino acid Cl O 6-N-acetyl-2, 8-difluoroadenine Br OH CH3 O-amino acid Cl O 6-N-acetyl-2-aminoadenine Br OH CH3 O-amino acid Cl O 6-N-acetyl-2-amino-8-fluoroadenine Br OH CH3 O-amino acid Cl O 2-N-acetylaminoadenine Br OH CH3 O-amino acid Cl O 2-N-acetylamino-8-fluoroadenine Br OH CH3 O-amino acid Cl O 2-N-acetylamino-8-fluorohypoxanthine Br OH CH3 O-amino acid Cl O 2-N-acetylaminohypoxanthine Br OH CH3 O-amino acid Cl O Thymine Cl _ CH3 0-amino acid Cl 0 Uracil Cl H R6 R'R8 X Base Rl° R9 CH3 0-amino acid Cl 0 Guanine Cl H CH3 O-amino acid Cl O Cytosine Cl H CH3 O-amino acid Cl O Adenine Cl H CH3 0-amino acid Cl O Hypoxanthine Cl H CH3 O-amino acid Cl O 5-Fluorouracil Cl H CH3 O-amino acid Cl O 8-Fluoroguanine Cl H CH3 O-amino acid Cl O 5-Fluorocytosine Cl H CH3 O-amino acid Cl O 8-Fluoroadenine Cl H CH3 O-amino acid Cl O 2-Fluoroadenine Cl H CH3 0-amino acid Cl 0 2, 8-Difluoroadenine Cl H CH3 O-amino acid Cl O 2-Fluorohypoxanthine Cl H CH3 O-amino acid Cl O 8-Fluorohypoxanthine Cl H CH3 O-amino acid Cl O 2, 8-Difluorohypoxanthine Cl H CH3 O-amino acid Cl O 2-Aminoadenine Cl H CH3 O-amino acid Cl O 2-Amino-8-fluoroadenine Cl H CH3 O-amino acid Cl O 2-Amino-8-fluorohypoxanthine Cl H CH3 O-amino acid Cl O 2-Aminohypoxanthine Cl H CH3 O-amino acid Cl O 2-N-acetylguanine Cl H CH3 O-amino acid Cl O 4-N-acetylcytosine Cl H CH3 0-amino acid Cl 0 6-N-acetyladenine Cl H CH3 O-amino acid Cl O 2-N-acetyl-8-fluoroguanine Cl H CH3 O-amino acid Cl O 4-N-acetyl-5-fluorocytosine Cl H CH3 O-amino acid Cl O 6-N-acetyl-2-fluoroadenine Cl H CH3 O-amino acid Cl O 6-N-acetyl-2, 8-difluoroadenine Cl H CH3 O-amino acid Cl O 6-N-acetyl-2-aminoadenine Cl H CH3 O-amino acid Cl O 6-N-acetyl-2-amino-8-fluoroadenine Cl H CH3 O-amino acid Cl O 2-N-acetylaminoadenine Cl H CH3 O-amino acid Cl O 2-N-acetylamino-8-fluoroadenine Cl H CH3 O-amino acid Cl O 2-N-acetylamino-8-fluorohypoxanthine Cl H CH3 O-amino acid Cl O 2-N-acetylaminohypoxanthine Cl H CH3 O-amino acid Cl O Thymine Cl O-amino acid CH3 O-amino acid CI O Uracil Cl 0-amino acid CH3 O-amino acid Cl O Guanine Cl O-amino acid CH3 O-amino acid Cl O Cytosine Cl O-amino acid CH3 O-amino acid Cl O Adenine Cl O-amino acid CH3 O-amino acid Cl O Hypoxanthine Cl O-amino acid CH3 O-amino acid Cl O 5-Fluorouracil Cl O-amino acid CH3 O-amino acid Cl O 8-Fluoroguanine Cl O-amino acid CH3 O-amino acid Cl O 5-Fluorocytosine Cl O-amino acid CH3 O-amino acid Cl O 8-Fluoroadenine Cl O-amino acid CH3 O-amino acid Cl O 2-Fluoroadenine Cl O-amino acid CH3 O-amino acid Cl O 2, 8-Difluoroadenine Cl O-amino acid CH3 0-amino acid Cl O 2-Fluorohypoxanthine Cl O-amiçacid CH3 O-amino acid Cl O 8-Fluorohypoxanthine Cl O-amino acid CH3 O-amino acid Cl O 2, 8-Difluorohypoxanthine Cl O-amino acid CH3 O-amino acid Cl O 2-Aminoadenine Cl O-amino acid CH3 O-amino acid Cl 0 2-Amino-8-fluoroadenine Cl 0-amino acid R"R'R X Base R Rv CH3 O-amino acid Cl O 2-Amino-8-fluorohypoxanthine Cl O-amino acid CH3 O-amino acid Cl O 2-Aminohypoxanthine Cl O-amino acid CH3 O-amino acid Cl O 2-N-acetylguanine Cl O-amino acid CH3 O-amino acid Cl O 4-N-acetylcytosine Cl O-amino acid CH3 O-amino acid Cl O 6-N-acetyladenine Cl O-amino acid CH3 O-amino acid Cl O 2-N-acetyl-8-fluoroguanine Cl O-amino acid CH3 O-amino acid Cl O 4-N-acetyl-5-fluorocytosine Cl O-amino acid CH3 O-amino acid Cl O 6-N-acetyl-2-fluoroadenine Cl O-amino acid CH3 O-amino acid Cl O 6-N-acetyl-2, 8-difluoroadenine Cl O-amino acid CH3 O-amino acid Cl O 6-N-acetyl-2-aminoadenine Cl O-amino acid CH3 O-amino acid Cl O 6-N-acetyl-2-amino-8-fluoroadenine Cl O-amino acid CH3 O-amino acid Cl O 2-N-acetylaminoadenine Cl O-amino acid CH3 O-amino acid Cl O 2-N-acetylamino-8-fluoroadenine Cl O-amino acid CH3 O-amino acid Cl O 2-N-acetylamino-8-fluorohypoxanthine Cl O-amino acid CH3 O-amino acid Cl O 2-N-acetylaminohypoxanthine Cl O-amino acid CH3 O-amino acid Cl O Thymine Cl 0-acyl CH3 O-amino acid Cl O Uracil Cl O-acyl CH3 O-amino acid Cl O Guanine Cl O-acyl CH3 0-amino acid Cl O Cytosine Cl O-acyl CH3 O-amino acid Cl O Adenine Cl O-acyl CH3 O-amino acid Cl O Hypoxanthine Cl O-acyl CH3 O-amino acid Cl O 5-Fluorouracil Cl O-acyl CH3 O-amino acid Cl O 8-Fluoroguanine Cl O-acyl CH3 0-amino acid Cl O 5-Fluorocytosine Cl O-acyl CH3 O-amino acid Cl O 8-Fluoroadenine Cl O-acyl CH3 O-amino acid Cl O 2-Fluoroadenine Cl O-acyl CH3 O-amino acid Cl O 2, 8-Difluoroadenine Cl O-acyl CH3 O-amino acid Cl O 2-FluorohyDoxanthine Cl O-acyl CH3 O-amino acid Cl O 8-Fluorohypoxanthine Cl O-acyl CH3 O-amino acid Cl O 2, 8-Difluorohypoxanthine Cl O-acyl CH3 0-amino acid Cl 0 2-Aminoadenine Cl 0-acyl CH3 O-amino acid Cl O 2-Amino-8-fluoroadenine Cl O-acyl CH3 O-amino acid Cl O 2-Amino-8-fluorohypoxanthine Cl O-acyl CH3 O-am ino acid Cl O 2-AminohyDoxanthine Cl O-acyl CH3 O-amino acid Cl O 2-N-acetylguanine Cl O-acyl CH3 O-amino acid Cl O 4-N-acetylcytosine Cl O-acyl CH3 0-amino acid Cl O 6-N-acetyladenine Cl O-acyl CH3 O-amino acid Cl O 2-N-acetyl-8-fluoroguanine Cl O-acyl CH3 O-amino acid Cl O 4-N-acetyl-5-fluorocytosine Cl O-acyl CH3 O-amino acid Cl O 6-N-acetyl-2-fluoroadenine Cl O-acyl CH3 O-amino acid Cl O 6-N-acetyl-2, 8-difluoroadenine Cl O-acyl CH3 O-amino acid Cl O 6-N-acetyl-2-aminoadenine Cl O-acyl CH3 O-amino acid Cl O 6-N-acetyl-2-amino-8-fluoroadenine Cl O-acyl CH3 O-amino acid Cl O 2-N-acetylaminoadenine Cl O-acyl CH3 O-am ino acid Cl O 2-N-acetylam ino-8-fluoroadenine Cl O-ac CH3 O-amino acid Cl O 2-N-acetylamino-8-fluorohyDoxanthine Cl O-acyI CH3 O-amino acid Cl O 2-N-acetylaminohypoxanthine Cl O-acyl R R R X Base l Rl° R9 CH3 O-amino acid Cl O Thymine l OH CH3 O-amino acid Cl 0 Uracil Cl OH CH3 O-amino acid Cl O Guanine Cl OH CH3 O-amino acid Cl O Cytosine Cl OH CH3 O-amino acid Cl O Adenine Cl OH CH3 0-amino acid Cl O Hypoxanthine Cl OH CH3 O-amino acid Cl O 5-Fluorouracil Cl OH CH3 O-amino acid Cl O 8-Fluoroguanine Cl OH CH3 O-amino acid Cl O 5-Fluorocytosine Cl OH CH3 O-amino acid Cl O 8-Fluoroadenine Cl OH CH3 O-amino acid Cl O 2-Fluoroadenine Cl OH CH3 O-amino acid Cl 0 2, 8-Difluoroadenine Cl OH CH3 O-amino acid Cl O 2-Fluorohypoxanthine Cl OH CH3 O-amino acid Cl O 8-Fluorohypoxanthine Cl OH CH3 0-amino acid CI O 2, 8-Difluorohypoxanthine Cl OH CH3 O-amino acid Cl O 2-Aminoadenine Cl OH CH3 O-amino acid Cl O 2-Amino-8-fluoroadenine Cl OH CH3 O-amino acid C1 O 2-Amino-8-fluorohy oxanthine C1 OH CH3 O-amino acid Cl O 2-Aminohypoxanthine Cl OH CH3 O-amino acid Cl O 2-N-acetylguanine Cl OH CH3 O-amino acid Cl O 4-N-acetylcytosine Cl OH CH3 O-amino acid Cl O 6-N-acetyladenine Cl OH CH3 0-amino acid Cl O 2-N-acetyl-8-fluoroguanine Cl OH CH3 O-amino acid Cl O 4-N-acetyl-5-fluorocytosine Cl OH CH3 O-amino acid Cl O 6-N-acetyl-2-fluoroadenine Cl OH CH3 O-amino acid Cl O 6-N-acetyl-2, 8-difluoroadenine Cl OH CH3 O-amino acid Cl O 6-N-acetyl-2-aminoadenine Cl OH CH3 O-amino acid Cl O 6-N-acetyl-2-amino-8-fluoroadenine Cl OH CH3 O-amino acid Cl O 2-N-acetylaminoadenine Cl OH CH3 O-amino acid Cl O 2-N-acetylamino-8-fluoroadenine Cl OH CH3 0-amino acid Cl O 2-N-acetylamino-8-fluorohypoxanthine Cl OH CH3 O-amino acid Cl O 2-N-acetylaminohypoxanthine Cl OH CH3 0-amino acid Cl 0 Thymine H H CH3 O-amino acid Cl O Uracil H H CH3 O-amino acid Cl O Guanine H H CH3 0-amino acid Cl O Cytosine H H CH3 O-amino acid Cl O Adenine H H CH3 0-amino acid Cl 0 Hypoxanthine H H CH3 O-amino acid Cl O 5-Fluorouracil H H CH3 0-amino acid Cl O 8-Fluoroguanine H H CH3 0-amino acid Cl O 5-Fluorocytosine H H CH3 O-amino acid Cl O 8-Fluoroadenine H H CH3 O-amino acid Cl O 2-Fluoroadenine H H CH3 0-amino acid Cl 0 2, 8-Difluoroadenine H H CH3 O-amino acid Cl O 2-Fluorohypoxanthine H H CH3 O-amino acid Cl O 8-Fluorohypoxanthine H H CH3 0-amino acid Cl 0 2, 8-Difluorohypoxanthine H H R6 R7 R8 X Base-F R9 CH3 O-amino acid Cl 0 2-Aminoadenine H H CH3 0-amino acid Cl 0 2-Amino-8-fluoroadenine H H CH3 O-amino acid Cl O 2-Amino-8-fluorohypoxanthine H H CH3 O-amino acid Cl O 2-Aminohypoxanthine H H CH3 O-amino acid Cl O 2-N-acetylguanine H H CH3 O-amino acid Cl O 4-N-acetylcytosine H H CH3 O-amino acid Cl O 6-N-acetyladenine H H CH3 O-amino acid Cl O 2-N-acetyl-8-fluoroguanine H H CH3 O-amino acid Cl O 4-N-acetyl-5-fluorocytosine H H CH3 O-amino acid Cl O 6-N-acetyl-2-fluoroadenine H H CH3 O-amino acid Cl O 6-N-acetyl-2, 8-difluoroadenine H H CH3 O-amino acid Cl O 6-N-acetyl-2-aminoadenine H H CH3 O-amino acid Cl O 6-N-acetyl-2-amino-8-fluoroadenine H H CH3 O-amino acid Cl O 2-N-acetylaminoadenine H H CH3 O-amino acid Cl O 2-N-acetylamino-8-fluoroadenine H H CH3 0-amino acid Cl O 2-N-acetylamino-8-fluorohypoxanthine H H CH3 0-amino acid Cl O 2-N-acetylaminohypoxanthine H H CH3 O-amino acid C1 O Thymine H O-amino acid CH3 O-amino acid ci O Uracil H O-amino acid CH3 0-amino acid Cl O Guanine H 0-amino acid CH3 O-amino acid Cl O Cytosine H O-amino acid CH3 0-amino acid Cl 0 Adenine H 0-amino acid CH3 O-amino acid Cl O Hypoxanthine H O-amino acid CH3 O-amino acid Cl O 5-Fluorouracil H 0-amino acid CH3 O-amino acid Cl O 8-Fluoroguanine H O-amino acid CH3 O-amino acid Cl O 5-Fluorocytosine H O-amino acid CH3 O-amino acid Cl O 8-Fluoroadenine H O-amino acid CH3 O-amino acid Cl O 2-Fluoroadenine H O-amino acid CH3 0-amino acid Cl 0 2, 8-Difluoroadenine H O-amino acid CH3 O-amino acid Cl 0 2-Fluorohypoxanthine H 0-amino acid CH3 O-amino acid Cl O 8-Fluorohypoxanthine H O-amino acid CH3 O-amino acid Cl O 2, 8-Difluorohypoxanthine H O-amino acid CH3 O-amino acid Cl O 2-Aminoadenine H O-amino acid CH3 O-amino acid Cl O 2-Amino-8-fluoroadenine H O-amino acid CH3 O-amino acid Cl O 2-Amino-8-fluorohypoxanthine H O-amino acid CH3 O-amino acid Cl O 2-AminohypoxanthineH 0-amino acid CH3 O-amino acid Cl O 2-N-acetylguanine H O-amino acid CH3 O-amino acid Cl O 4-N-acetylcytosine H O-amino acid CH3 0-amino acid C) 0 6-N-acetyladenine H 0-amino acid CH3 O-amino acid Cl O 2-N-acetyl-8-fluoroguanine H O-amino acid CH3 O-amino acid Cl O 4-N-acetyl-5-fluorocytosine H O-amino acid CH3 O-amino acid Cl O 6-N-acetyl-2-fluoroadenine H O-amino acid CH3 O-amino acid Cl O 6-N-acetyl-2, 8-difluoroadenine H O-amino acid CH3 O-amino acid Cl O 6-N-acetyl-2-aminoadenine H O-amino acid CH3 O-amino acid Cl O od z n H O-amino acid CH3 0-amino acid CI O 2-N-acetylaminoadenine H O-amino acid CH3 O-amino acid Cl O 2-N-acetylam ino-8-fluoroadenine H O-am ino acid R6 R R X Base R R CH3 O-amino acid Cl O 2-N-acetylamino-8-fluorohypoxanthine H O-amino acid CH3 O-amino acid Cl O 2-N-acetylaminohypoxanthine H O-amino acid CH3 O-amino acid Cl O Thymine H O-acyl CH3 O-amino acid Cl O Uracil H O-acyl CH3 O-amino acid Cl O Guanine H O-acy1 y CH3 O-amino acid Cl O Ctosine H O-acyl CH3 O-amino acid Cl O Adenine H O-acyl CH3 O-amino acid Cl O Hypoxanthine H O-acyl CH3 O-amino acid Cl O 5-Fluorouracil H O-acyl CH3 O-amino acid Cl O 8-Fluoroguanine H O-acyl CH3 O-amino acid Cl O 5-Fluorocytosine H O-acyl CH3 O-amino acid Cl O 8-Fluoroadenine H O-acyl CH3 O-amino acid Cl O 2-Fluoroadenine H O-acyl CH3 O-amino acid Cl 0 2, 8-Difluoroadenine H O-acyl CH3 O-amino acid Cl O 2-Fluorohypoxanthine H 0-acyl CH3 O-amino acid Cl O 8-Fluorohypoxanthine H O-acyl CH3 O-amino acid Cl 0 2, 8-Difluorohypoxanthine H O-acyl CH3 O-amino acid Cl O 2-Aminoadenine H O-acyl CH3 O-amino acid Cl O 2-Amino-8-fluoroadenine H O-acyl CH3 O-amino acid Cl 0 2-Amino-8-fluorohypoxanthine H 0-acyl CH3 O-amino acid Cl 0 2-Aminohypoxanthine H 0-acyl CH3 O-amino acid Cl 0 2-N-acetylguanine H 0-acyl v CH3 O-amino acid Cl O 4-N-acetylcytosine H O-acyl CH3 O-amino acid Cl O 6-N-acetyladenine H O-acyl CH3 O-amino acid Cl O 2-N-acetyl-8-fluoroguanine H O-acyl CH3 O-amino acid Cl O 4-N-acetyl-5-fluorocytosine H O-acyl CH3 O-amino acid Cl O 6-N-acetyl-2-fluoroadenine H O-acyl CH3 O-amino acid Cl O 6-N-acetyl-2, 8-difluoroadenine H O-acyl CH3 O-amino acid Cl O 6-N-acet 1-2-aminoadenine H O-ac 1 CH3 0-amino acid Cl O 6-N-acetyl-2-amino-8-fluoroadenine H O-acyl CH3 O-amino acid Cl O 2-N-acetylaminoadenine H O-acyl CH3 O-amino acid Cl O 2-N-acetylamino-8-fluoroadenine H O-acyl CH3 0-amino acid Cl O 2-N-acetylamino-8-fluorohypoxanthine H O-acyl CH3 O-amino acid Cl O 2-N-acetylaminohypoxanthine H O-acyl CH3 O-amino acid Cl O Thymine H OH CH3 O-amino acid C1 O Uracil H OH CH3 O-amino acid Cl O Guanine H OH CH3 O-amino acid Cl O C osine H OH CH3 O-amino acid Cl O Adenine H OH CH3 O-amino acid Cl O Hypoxanthine H OH CH3 O-amino acid Cl O 5-Fluorouracil H OH CH3 O-amino acid Cl O 8-Fluoroguanine H OH CH3 O-amino acid Cl O 5-Fluorocytosine H OH CH3 O-amino acid Cl O 8-Fluoroadenine H OH CH3 0-amino acid Cl O 2-Fluoroadenine H OH CH3 O-amino acid Cl O 2, 8-Difluoroadenine H OH CH3 O-amino acid Cl O 2-Fluorohypoxanthine H OH R6 R7 R8 X Base R R CH3 O-amino acid Cl O 8-Fluorohypoxanthine H OH CH3 O-amino acid Cl O 2, 8-Difluorohypoxanthine H OH CH3 O-amino acid Cl O 2-Aminoadenine H OH CH3 0-amino acid Cl 0 2-Amino-8-fluoroadenine H OH CH3 0-amino acid Cl 0 2-Amino-8-fluorohypoxanthine H OH CH3 0-amino acid Cl 0 2-Aminohypoxanthine H OH CH3 O-amino acid Cl O 2-N-acetylguanine H OH CH3 O-amino acid Cl O 4-N-acetyIcytosine H OH CH3 O-amino acid Cl O 6-N-acetyladenine H OH CH3 O-amino acid Cl O 2-N-acetyl-8-fluoroguanine H OH CH3 O-amino acid Cl O 4-N-acetyl-5-fluorocytosine H OH CH3 0-amino acid Cl 0 6-N-acetyl-2-fluoroadenine H OH CH3 O-amino acid Cl O 6-N-acetyl-2, 8-difluoroadenine H OH CH3 O-amino acid Cl O 6-N-acetyl-2-aminoadenine H OH CH3 O-amino acid Cl O 6-N-acetyl-2-amino-8-fluoroadenine H OH CH3 O-amino acid Cl O 2-N-acetylaminoadenine H OH CH3 O-amino acid Cl O 2-N-acetylamino-8-fluoroadenine H OH CH3 O-amino acid Cl O 2-N-acetylamino-8-fluorohypoxanthine H OH CH3 O-amino acid Cl O 2-N-acetylaminohypoxanthine H OH CH3 0-amino acid Cl 0 Thymine OH H CH3 O-amino acid Cl O Uracil OH H CH3 0-amino acid Cl 0 Guanine OH H CH3 O-amino acid Cl O Cytosine OH H CH3 0-amino acid Cl 0 Adenine OH H CH3 0-amino acid Cl 0 Hypoxanthine OH H CH3 O-amino acid Cl O 5-Fluorouracil OH H CH3 O-amino acid Cl O 8-Fluoroguanine OH H CH3 O-amino acid Cl O 5-Fluorocytosine OH H CH3 O-amino acid Cl O 8-Fluoroadenine OH H CH3 O-amino acid Cl O 2-Fluoroadenine OH H CH3 O-amino acid Cl O 2, 8-Difluoroadenine OH H CH3 O-amino acid Cl O 2-Fluorohypoxanthine OH H CH3 0-amino acid Cl 0 8-Fluorohypoxanthine OH H CH3 O-amino acid Cl O 2, 8-Difluorohypoxanthine OH H CH3 O-amino acid Ci O 2-Aminoadenine OH H CH3 O-amino acid Cl O 2-Amino-8-fluoroadenine OH H CH3 O-amino acid Cl O 2-Amino-8-fluorohypoxanthine OH H CH3 O-amino acid Cl O 2-Aminohypoxanthine OH H CH3 O-amino acid Cl O 2-N-acetylguanine OH H CH3 O-amino acid Cl O 4-N-acetylcytosine OH H CH3 O-amino acid Cl O 6-N-acetyladenine OH H CH3 O-amino acid Cl O 2-N-acetyl-8-fluoroguanine OH H CH3 O-amino acid Cl O 4-N-acetyl-5-fluorocytosine OH H CH3 0-amino acid Cl 0 6-N-acetyl-2-fluoroadenine OH H CH3 O-amino acid Cl O 6-N-acetyl-2, 8-difluoroadenine OH H CH3 O-amino acid Cl O 6-N-acet 1-2-aminoadenine OH H CH3 0-amino acid Cl O 6-N-acetyl-2-amino-8-fluoroadenine OH H R6 R'RS X Base Rl° R9 CH3 O-amino acid Cl O 2-N-acetylaminoadenine OH H CH3 O-amino acid Cl O 2-N-acetylamino-8-fluoroadenine OH H CH3 0-amino acid Cl O 2-N-acetylamino-8-fluorohypoxanthine OH H CH3 O-amino acid Cl O 2-N-acetylaminohypoxanthine OH H CH3 O-amino acid H O Thymine F H CH3 O-amino acid H O Uracil F H CH3 O-amino acid H O Guanine F H CH3 O-amino acid H O Cytosine F H CH3 O-amino acid H 0 Adenine F H CH3 O-amino acid H O Hypoxanthine F H CH3 O-amino acid H O 5-Fluorouracil F H CH3 O-amino acid H O 8-Fluoroguanine F H CH3 O-amino acid H O 5-Fluorocytosine F H CH3 O-amino acid H O 8-Fluoroadenine F H CH3 O-amino acid H O 2-Fluoroadenine F H CH3 O-amino acid H O 2, 8-Difluoroadenine F H CH3 O-amino acid H O 2-Fluorohypoxanthine F H CH3 O-amino acid H O 8-Fluorohy oxanthine F H CH3 O-amino acid H O 2, 8-Difluorohypoxanthine F H CH3 O-amino acid H O 2-Aminoadenine F H CH3 O-amino acid H O 2-Amino-8-fluoroadenine F H CH3 O-amino acid H O 2-Amino-8-fluorohypoxanthine F H CH3 0-amino acid H O 2-Aminohypoxanthine F H CH3 O-amino acid H O 2-N-acetylguanine F H CH3 O-amino acid H O 4-N-acetylcytosine F H CH3 O-amino acid H O 6-N-acetyladenine F H CH3 O-amino acid H O 2-N-acetyl-8-fluoroguanine F H CH3 O-amino acid H O 4-N-acet 1-5-fluoroc osine F H CH3 O-amino acid H O 6-N-acetyl-2-fluoroadenine F H CH3 O-amino acid H O 6-N-acetyl-2, 8-difluoroadenine F H CH3 O-amino acid H 0 6-N-acetyl--aminoadenine F H CH3 O-amino acid H 0 6-N-acetyl-2-amino-8-fluoroadenine F H CH3 O-amino acid H O 2-N-acetylaminoadenine F H CH3 O-amino acid H O 2-N-acetylamino-8-fluoroadenine F H CH3 O-amino acid H O 2-N-acetylamino-8-fluorohypoxanthine F H CH3 O-amino acid H O 2-N-acetylaminohypoxanthine F H CH3 O-amino acid H O Thymine F 0-amino acid CH3 0-amino acid H O Uracil F O-amino acid CH3 O-amino acid H O Guanine F O-amino acid CH3 O-amino acid H O Cytosine F O-amino acid CH3 O-amino acid H O Adenine F O-amino acid CH3 O-amino acid H O Hypoxanthine F O-amino acid CH3 O-amino acid H O 5-Fluorouracil F O-amino acid CH3 O-amino acid H O 8-Fluoroguanine F O-amino acid CH3 O-amino acid H O 5-Fluorocytosine F O-amino acid CH3 O-amino acid H O 8-Fluoroadenine F O-amino acid CH3 O-amino acid H O 2-Fluoroadenine F O-amino acid F R'R8 X Base-F R9 CH3 O-amino acid H O 2, 8-Difluoroadenine F O-amino acid CH3 0-amino acid H O 2-Fluorohypoxanthine F 0-amino acid CH3 0-amino acid H O 8-Fluorohypoxanthine F O-amino acid CH3 O-amino acid H 0 2, 8-Difluorohypoxanthine F O-amino acid CH3 O-amino acid H O 2-Aminoadenine F O-amino acid CH3 O-amino acid H O 2-Amino-8-fluoroadenine F O-amino acid CH3 O-amino acid H O 2-Amino-8-fluorohypoxanthine F O-amino acid CH3 O-amino acid H O 2-Aminohypoxanthine F 0-amino acid CH3 O-amino acid H O 2-N-acetylguanine F 0-amino acid CH3 O-amino acid H O 4-N-acetylcytosine F 0-amino acid CH3 O-amino acid H O 6-N-acetyladenine F O-amino acid CH3 0-amino acid H 0 2-N-acetyl-8-fluoroguanine F 0-amino acid CH3 O-amino acid H O 4-N-acetyl-5-fluorocytosine F O-amino acid CH3 O-amino acid H O 6-N-acetyl-2-fluoroadenine F O-amino acid CH3 O-amino acid H O 6-N-acetyl-2, 8-difluoroadenine F O-amino acid CH3 O-amino acid H O 6-N-acetyl-2-aminoadenine F O-amino acid CH3 O-amino acid H 0 6-N-acetyl-2-amino-8-fluoroadenine F O-amino acid CH3 0-amino acid H O 2-N-acetylaminoadenine F O-amino acid CH3 0-amino acid H O 2-N-acetylamino-8-fluoroadenine F O-amino acid CH3 0-amino acid H O 2-N-acetylamino-8-fluorohypoxanthine F O-amino acid CH3 0-amino acid H O 2-N-acetylaminohypoxanthine F 0-amino acid CH3 O-amino acid H O Thymine F O-acyl CH3 O-amino acid H O Uracil F O-acyl CH3 O-amino acid H 0 Guanine F 0-acyl CH3 O-amino acid H O Cytosine _ F O-acyl CH3 O-amino acid H O Adenine F O-acyl CH3 O-amino acid H O Hypoxanthine F O-acyl CH3 O-amino acid H O 5-Fluorouracil F O-acyl CH3 0-amino acid H O 8-Fluoroguanine F 0-acyl CH3 O-amino acid H O 5-Fluorocytosine F O-acyl CH3 O-amino acid H O 8-Fluoroadenine F O-acyl CH3 0-amino acid H O 2-Fluoroadenine F O-acyI CH3 0-amino acid H O 2, 8-Difluoroadenine F O-acyl CH3 O-amino acid H O 2-Fluorohypoxanthine F O-acyl CH3 O-amino acid H O 8-Fluorohypoxanthine F 0-acyl CH3 O-amino acid H O 2, 8-Difluorohypoxanthine F O-acyl CH3 0-amino acid H O 2-Aminoadenine F O-acyl CH3 O-amino acid H O 2-Amino-8-fluoroadenine F O-acyl CH3 0-amino acid H 0 2-Amino-8-fluorohypoxanthine F 0-acyl CH3 O-amino acid H O 2-Aminohypoxanthine F 0-acyl CH3 0-amino acid H O 2-N-acetyl guanine F 0-acyl CH3 O-amino acid H O 4-N-acetylcytosine F O-acyl CH3 O-amino acid H O 6-N-acetyladenine F 0-acyl CH3 O-amino acid H O 2-N-acetyl-8-fluoroguanine F O-acyl CH3 O-amino acid H O 4-N-acetyl-5-fluorocytosine F O-acyI CH3 O-amino acid H O 6-N-acetyl-2-fluoroadenine F O-acyl CH3 O-amino acid H 0 6-N-acetyl-2, 8-difluoroadenine F O-acyl R"R R° X Base R R CH3 O-amino acid H 0 6-N-acetyl-2-aminoadenine 0-acyl CH3 O-amino acid H O 6-N-acetyl-2-amino-8-fluoroadenine F O-acyl CH3 O-amino acid H O 2-N-acetylaminoadenine F O-acyl CH3 O-amino acid H O 2-N-acetylamino-8-fluoroadenine F O-acyl CH3 O-amino acid H O 2-N-acetylamino-8-fluorohypoxanthine F O-acyl CH3 O-amino acid H O 2-N-acetylaminohypoxanthine F O-acyl CH3 O-amino acid H 0 Thymine F OH CH3 O-amino acid H O Uracil F OH CH3 O-amino acid H O Guanine F OH CH3 O-amino acid H 0 Cytosine F OH CH3 O-amino acid H O Adenine F OH CH3 0-amino acid H O Hypoxanthine F OH CH3 O-amino acid H O 5-Fluorouracil F OH CH3 0-amino acid H O 8-Fluoroguanine F OH CH3 O-amino acid H O 5-Fluorocytosine F OH CH3 O-amino acid H O 8-Fluoroadenine F OH CH3 O-amino acid H O 2-Fluoroadenine F OH CH3 0-amino acid H O 2, 8-Difluoroadenine F OH CH3 0-amino acid H O 2-Fluorohypoxanthine F OH CH3 O-amino acid H 8-F) uorohypoxanthineJFOH CH3 O-amino acid H O 2, 8-Difluorohypoxanthine F OH CH3 0-amino acid H 0 2-Aminoadenine F OH CH3 O-amino acid H O 2-Amino-8-fluoroadenine F OH CH3 0-amino acid H O 2-Amino-8-fluorohypoxanthine F OH CH3 O-amino acid H O 2-Aminohypoxanthine F OH CH3 O-amino acid H 0 2-N-acetyl guanine F OH CH3 0-amino acid H O 4-N-acetylcytosine F OH CH3 0-amino acid H Q 6-N-acetyladenine F OH CH3 0-amino acid H O 2-N-acetyl-8-fluoroguanine F OH CH3 0-amino acid H O 4-N-acetyl-5-fluorocytosine F OH CH3 0-amino acid H Q 6-N-acetyl-2-fluoroadenine F OH CH3 O-amino acid H Q 6-N-acetyl-2, 8-difluoroadenine F OH CH3 0-amino acid H O 6-N-acetyl-2-aminoadenine F OH CH3 O-amino acid H O 6-N-acetyl-2-amino-8-fluoroadenine F OH CH3 O-amino acid H O 2-N-acetylaminoadenine F OH CH3 0-amino acid H O 2-N-acetylamino-8-fluoroadenine F OH CH3 0-amino acid H O 2-N-acetylamino-8-fluorohypoxanthine F OH CH3 O-amino acid H O 2-N-acetylaminohypoxanthine F OH CH3 O-amino acid H O Thymine Br H CH3 O-amino acid H O Uracil Br H CH3 O-amino acid H O Guanine Br H CH3 O-amino acid H O Cytosine Br H CH3 0-amino acid H O Adenine Br H CH3 O-amino acid H O Hypoxanthine Br H CH3 O-amino acid H O 5-Fluorouracil Br H CH3 0-amino acid_ H 0 8-Fluoroguanine Br H CH3 0-amino acid H Q 5-Fluorocytosine Br H R'R'R8 X Base R9 CH3 O-amino acid H O 8-Fluoroadenine Br H CH3 0-amino acid H O 2-Fluoroadenine Br H CH3 0-amino acid H 0 2, 8-Difluoroadenine Br H CH3 0-amino acid H O 2-Fluorohypoxanthine Br H CH3 0-amino acid H O 8-Fluoroh oxanthine Br H CH3 0-amino acid H O 2, 8-Difluorohypoxanthine Br H CH3 0-amino acid H O 2-Aminoadenine Br H CH3 0-amino acid H O 2-Amino-8-fluoroadenine Br H CH3 0-amino acid H O 2-Amino-8-fluorohypoxanthine Br H CH3 0-amino acid H O 2-Aminohypoxanthine Br H CH3 O-amino acid H O 2-N-acetylguanine Br H CH3 0-amino acid H O 4-N-acetylcytosine Br. _ CH3 O-amino acid H O 6-N-acetyladenine Br H CH3 0-amino acid H 0 2-N-acetyl-8-fluoroguanine Br H CH3 0-amino acid H O 4-N-acetyl-5-fluorocytosine Br H CH3 0-amino acid H O 6-N-acetyl-2-fluoroadenine Br H CH3 O-amino acid H O 6-N-acetyl-2, 8-difluoroadenine Br H CH3 O-amino acid H O 6-N-acetyl-2-aminoadenine Br H CH3 O-amino acid H O 6-N-acetyl-2-amino-8-fluoroadenine Br H CH3 O-amino acid H O 2-N-acetylaminoadenine Br H CH3 O-amino acid H O 2-N-acetylamino-8-fluoroadenine Br H CH3 O-amino acid H O 2-N-acetylamino-8-fluorohypoxanthine Br. _ CH3 0-amino acid H O 2-N-acetylaminohypoxanthine Br H CH3 0-amino acid H O Thymine Br O-amino acid CH3 O-amino acid H O Uracil Br 0-amino acid CH3 0-amino acid H O Guanine Br O-amino acid CH3 0-amino acid H O Cytosine Br O-amino acid CH3 O-amino acid H O Adenine Br O-amino acid CH3 0-amino acid H 0 Hypoxanthine Br 0-mino acid CH3 0-amino acid H O 5-Fluorouracil Br O-amino acid CH3 0-amino acid H 0 8-Fluoroguanine Br O-amino acid CH3 0-amino acid H 0 5-Fluorocytosine Br 0-amino acid CH3 0-amino acid H O 8-Fluoroadenine Br O-amino acid CH3 0-amino acid H 0 2-Fluoroadenine Br O-amino acid CH3 0-amino acid H 0 2, 8-Difluoroadenine Br O-amino acid CH3 0-amino acid H O 2-Fluorohypoxanthine Br O-amino acid CH3 0-amino acid H O 8-Fluorohypoxanthine Br 0-amino acid CH3 0-amino acid H O 2, 8-Difluorohypoxanthine Br O-amino acid CH3 0-amino acid H O 2-Aminoadenine Br O-amino acid CH3 O-amino acid H O 2-Amino-8-fluoroadenine Br O-amino acid CH3 0-amino acid H O 2-Amino-8-fluorohypoxanthine Br O-amino acid CH3 0-amino acid H O 2-Aminohypoxanthine Br O-amino acid CH3 0-amino acid H O 2-N-acetyl guanine Br 0-amino acid CH3 0-amino acid H O 4-N-acetylcytosine Br O-amino acid CH3 0-amino acid H 0 6-N-acetyladenine Br O-amino acid CH3 0-amino acid H O 2-N-acetyl-8-fluoroguanine Br O-amino acid CH3 0-amino acid H 0 4-N-acetyl-5-fluorocytosine Br O-amino acid r R7 W X Base R R CH3 O-amino acid H O 6-N-acetyl-2-fluoroadenine Br O-amino acid CH3 O-amino acid H Q 6-N-acetyl-2, 8-difluoroadenine | Br | O-amino acid CH3 0-amino acid H 0 6-N-acetyl-2-aminoadenine Br 0-amino acid CH3 O-amino acid H O 6-N-acety1-2-amino-8-fluoroadenine _ Br O-amino acid CH3 O-amino acid H O 2-N-acetylaminoadenine Br O-amino acid CH3 O-amino acid H O 2-N-acetylamino-8-fluoroadenine Br O-amino acid CH3 O-amino acid H O 2-N-acet lamino-8-fluorohy oxanthine Br O-amino acid CH3 O-amino acid H O 2-N-acetylaminohypoxanthine Br 0-amino acid CH3 O-amino acid H O Thymine Br O-acyI CH3 O-amino acid H O Uracil Br O-acyl CH3 0-amino acid H O Guanine Br O-acyl CH3 O-amino acid H 0 Cytosine Br 0-acyl CH3 O-amino acid H O Adenine Br O-acyl CH3 O-amino acid H O Hypoxanthine Br O-acyl CH3 O-amino acid H O 5-Fluorouraci I Br 0-a XI CH3 0-amino acid H O 8-Fluoroguanine Br O-acyl CH3 O-amino acid H 0 5-Fluorocytosine Br O-acyl CH3 O-amino acid H O 8-Fluoroadenine Br O-acyl CH3 0-amino acid H O 2-Fluoroadenine Br O-acyl CH3 0-amino acid H O 2, 8-Difluoroadenine Br O-acyl CH3 0-amino acid H O 2-Fluorohypoxanthine Br 0-acyl CH3 0-amino acid H 0 8-Fluorohypoxanthine Br O-acyl CH3 O-amino acid H O 2, 8-Difluorohypoxanthine Br O-acyl CH3 0-amino acid H O 2-Aminoadenine Br O-acyl CH3 0-amino acid H 0 2-Amino-8-fluoroadenine Br O-acyl CH3 O-amino acid H O 2-Amino-8-fluorohypoxanthine Br O-acyl CH3 O-amino acid H 0 2-Aminohy oxanthine Br O-ac 1 CH3 O-amino acid H 0 2-N-acetylguanine Br 0-acyl CH3 0-amino acid H Q 4-N-acetylcytosine Br O-acyl CH3 0-amino acid H O 6-N-acetyladenine Br O-acyl CH3 O-amino acid H O 2-N-acetyl-8-fluoroguanine Br O-acyl CH3 0-amino acid H O 4-N-acetyl-5-fluorocytosine Br O-acyl CH3 O-amino acid H O 6-N-acetyl-2-fluoroadenine Br O-acyl CH3 0-amino acid H O 6-N-acetyl-2, 8-difluoroadenine Br O-acyl CH3 0-amino acid H O 6-N-acetyl-2-aminoadenine Br O-acyl CH3 0-amino acid H O 6-N-acetyl-2-amino-8-fluoroadenine Br O-acyl CH3 0-amino acid H O 2-N-acetylaminoadenine Br O-acyl CH3 O-amino acid H O 2-N-acetylamino-8-fluoroadenine Br O-acyl CH3 0-amino acid H O 2-N-acetylamino-8-fluorohypoxanthine Br O-acyl CH3 O-amino acid H O 2-N-acetylaminohypoxanthine Br O-acyl CH3 0-amino acid H O Thymine Br OH CH3 0-amino acid H O Uracil Br OH CH3 0-amino acid H O Guanine Br OH CH3 0-amino acid H O Cytosine Br OH CH3 0-amino acid H O Adenine Br OH CH3 0-amino acid H O Hypoxanthine Br OH CH3 O-amino acid H O 5-Fluorouracil Br OH R6 R'R8 X Base Rl° R9 CH3 0-amino acid H O 8-Fluoroguanine Br OH CH3 0-amino acid H O 5-Fluorocytosine Br OH CH3 0-amino acid H O 8-Fluoroadenine Br OH CH3 0-amino acid H O 2-Fluoroadenine Br OH CH3 0-amino acid H O 2, 8-Difluoroadenine Br OH CH3 0-amino acid H O 2-Fluorohypoxanthine Br OH CH3 O-amino acid H O 8-Fluorohypoxanthine Br OH CH3 0-amino acid H O 2, 8-Difluorohypoxanthine Br OH CH3 0-amino acid H O 2-Aminoadenine Br OH CH3 O-amino acid H O 2-Amino-8-fluoroadenine Br OH CH3 O-amino acid H Q 2-Amino-8-fluorohypoxanthine Br OH CH3 0-amino acid H O 2-Aminohypoxanthine Br OH CH3 O-amino acid H 0 2-N-acetylguanine Br OH CH3 O-amino acid H O 4-N-acetylcytosine Br OH CH3 O-amino acid H 0 6-N-acetyladenine Br OH CH3 O-amino acid H O 2-N-acetyl-8-fluoroguanine Br OH CH3 O-amino acid H 0 4-N-acetyl-5-fluorocytosine Br OH CH3 O-amino acid H O 6-N-acetyl-2-fluoroadenine Br OH CH3 O-amino acid H O 6-N-acetyl-2, 8-difluoroadenine Br OH CH3 O-amino acid H O 6-N-acetyl-2-aminoadenine Br OH CH3 O-amino acid H O 6-N-acetyl-2-amino-8-fluoroadenine Br OH CH3 O-amino acid H 0 2-N-acetylaminoadenine Br OH CH3 0-amino acid H O 2-N-acetylamino-8-fluoroadenine Br OH CH3 O-amino acid H O 2-N-acetylamino-8-fluorohypoxanthine Br OH CH3 O-amino acid H O 2-N-acetylaminohypoxanthine Br OH CH3 O-amino acid H O Thymine Cl H CH3 O-amino acid H 0 Uracil Cl H CH3 0-amino acid H O Guanine Cl H CH3 O-amino acid H O Cytosine Cl H CH3 O-amino acid H O Adenine Cl H CH3 0-amino acid H O Hypoxanthine Cl H CH3 O-amino acid H O 5-Fluorouracil Cl H CH3 O-amino acid H O 8-Fluoroguanine Cl H CH3 O-amino acid H O 5-Fluorocytosine C1 H CH3 0-amino acid H O 8-Fluoroadenine Cl H CH3 O-amino acid H O 2-Fluoroadenine Cl H CH3 0-amino acid H O 2, 8-Difluoroadenine Cl H CH3 0-amino acid H O 2-Fluorohypoxanthine Cl H CH3 0-amino acid H O 8-Fluorohy oxanthine CI H CH3 O-amino acid H O 2, 8-Difluorohy oxanthine Cl H CH3 O-amino acid H O 2-Aminoadenine Cl H CH3 0-amino acid H O 2-Amino-8-fluoroadenine Cl H CH3 0-amino acid H O 2-Amino-8-fluorohypoxanthine Cl H CH3 O-amino acid H O 2-Aminohypoxanthine Cl H CH3 O-amino acid H 0 2-N-acetylguanine Cl H CH3 O-amino acid H O 4-N-acetylc osine CI H CH3 O-amino acid H O 6-N-acetyladenine Cl H R"R R X Base R R CH3 pO-amino acid H 02-N-acetyl-8-fluoroguanine Cl H CH3 O-amino acid H O 4-N-acetyl-5-fluorocytosine Cl H CH3 O-amino acid H O 6-N-acetyl-2-fluoroadenine Cl H CH3 O-amino acid H O 6-N-acetyl-2, 8-difluoroadenine Cl H CH3 O-amino acid H O 6-N-acetyl-2-aminoadenine Ci H CH3 O-amino acid H O 6-N-acetyl-2-amino-8-fluoroadenine Cl H CH3 O-amino acid H O 2-N-acetylaminoadenine Cl H CH3 O-amino acid H O 2-N-acetylamino-8-fluoroadenine Cl H CH3 O-amino acid H O 2-N-acetylamino-8-fluorohypoxanthine Cl H CH3 O-amino acid H O 2-N-acetylaminohypoxanthine Cl H CH3 O-amino acid H O Thymine Cl O-amino acid CH3 O-amino acid H O Uracil Cl O-amino acid CH3 O-amino acid H O Guanine Cl O-amino acid CH3 O-amino acid H O Cytosine Cl O-amino acid CH3 O-amino acid H O Adenine _ Cl O-amino acid CH3 O-amino acid H O Hypoxanthine Cl O-amino acid CH3 O-amino acid H O 5-Fluorouracil Cl O-amino acid CH3 O-amino acid H O 8-Fluoroguanine Cl_ O-amino acid CH3 O-amino acid H O 5-Fluorocytosine _ Cl O-amino acid CH3 O-amino acid H O 8-Fluoroadenine Cl O-amino acid CH3 O-amino acid H O 2-Fluoroadenine Cl O-amino acid CH3 O-amino acid H O 2, 8-Difluoroadenine Cl O-amino acid CH3 O-amino acid H O 2-Fluorohypoxanthine Cl O-amino acid CH3 O-amino acid H O 8-Fluorohypoxanthine Cl 0-amino acid CH3 O-amino acid H O 2, 8-Difluorohypoxanthine Cl O-amino acid CH3 O-amino acid H O 2-Aminoadenine Cl O-amino acid CH3 O-amino acid H O 2-Amino-8-fluoroadenine Cl O-amino acid CH3 O-amino acid H O 2-Amino-8-fluorohypoxanthine Cl O-amino acid CH3 O-amino acid H O 2-Aminohypoxanthine Cl O-amino acid CH3 O-amino acid H O 2-N-acetylguanine CI O-amino acid CH3 O-amino acid H O 4-N-acetylcytosine Cl O-amino acid CH3 O-amino acid H O 6-N-acetyladenine Cl O-amino acid CH3 O-amino acid H O 2-N-acetyl-8-fluoroguanine Cl O-amino acid CH3 O-amino acid H O 4-N-acetyl-5-fluorocytosine Cl O-amino acid CH3 O-amino acid H O 6-N-acetyl-2-fluoroadenine Cl O-amino acid CH3 O-amino acid H O 6-N-acetyl-2, 8-difluoroadenine Cl O-amino acid CH3 O-amino acid H Q 6-N-acetyl-2-aminoadenine Cl O-amino acid CH3 O-amino acid H 06-N-acetyl-2-amino-8-fluoroadenine Cl 0-amino acid CH3 O-amino acid H O 2-N-acetylaminoadenine Cl O-amino acid CH3 O-amino acid H O 2-N-acetylamino-8-fluoroadenine Cl O-amino acid CH3 O-amino acid H O 2-N-acetylamino-8-fluorohypoxanthine Cl O-amino acid CH3 O-amino acid H O 2-N-acetylaminohypoxanthine Cl O-amino acid CH3 O-amino acid H O Thymine Cl O-acyl CH3 O-amino acid H O Uracil Cl O-acyl CH3 O-amino acid H O Guanine Cl O-acyl CH3 O-amino acid H 0Cytosine Cl 0-acyl CH3 O-amino acid H O Adenine Cl O-acyi R R'R X Base R CH3 O-amino acid H O Hypoxanthine _ Cl O-acyl CH3 O-amino acid H O 5-Fluorouracil Cl O-acyl CH3 0-amino acid H O 8-Fluoroguanine Cl O-acyl CH3 0-amino acid H O 5-Fluorocytosine Cl O-acyl CH3 0-amino acid H O 8-Fluoroadenine Cl O-acyl CH3 O-amino acid H O 2-Fluoroadenine Cl 0-acyl CH3 O-amino acid H O 2, 8-Difluoroadenine Cl O-acyl CH3 0-amino acid H O 2-Fluorohypoxanthine Cl O-acyl CH3 0-amino acid H O 8-Fluorohypoxanthine Cl O-acyl CH3 0-amino acid H O 2, 8-Difluorohypoxanthine Cl O-acyl CH3 O-amino acid H O 2-Aminoadenine Cl O-acyl CH3 0-amino acid H O 2-Amino-8-fluoroadenine Cl O-acyl CH3 O-amino acid H O 2-Amino-8-fluorohypoxanthine Cl O-acyl CH3 O-amino acid H O 2-Aminohypoxanthine Cl O-acyl CH3 0-amino acid H O 2-N-acetylguanine Cl O-acyl CH3 O-amino acid H O 4-N-acetylcytosine Cl O-acyl CH3 O-amino acid H O 6-N-acetyladenine Cl O-acyl CH3 O-amino acid H O 2-N-acetyl-8-fluoroguanine Cl O-acyl CH3 0-amino acid H O 4-N-acetyl-5-fluorocytosine C I O-acyl CH3 0-amino acid H O 6-N-acetyl-2-fluoroadenine Cl O-aceI CH3 0-amino acid H O 6-N-acetyl-2, 8-difluoroadenine Cl O-acyl CH3 O-amino acid H 0 6-N-acetyl-2-aminoadenine Cl 0-acyl CH3 O-amino acid H O 6-N-acetyl-2-amino-8-fluoroadenine Cl O-acyl CH3 0-amino acid H 0 2-N-acetylaminoadenine Cl 0-acyl CH3 O-amino acid H O 2-N-acetylamino-8-fluoroadenine Cl O-ac CH3 O-amino acid H O 2-N-acetylamino-8-fluorohypoxanthine Cl O-acyl CH3 O-amino acid H O 2-N-acetylaminohypoxanthine Cl O-acyl CH3 O-amino acid H O Thymine Cl OH CH3 0-amino acid H O Uracil Cl OH CH3 O-amino acid H O Guanine CI OH CH3 O-amino acid H 0 Cytosine Cl OH CH3 O-amino acid H O Adenine C1 OH CH3 0-amino acid H O Hypoxanthine Cl OH CH3 O-amino acid H O 5-Fluorouracil Cl OH CH3 0-amino acid H O 8-Fluoroguanine Cl OH CH3 O-amino acid H O 5-Fluorocytosine Cl OH CH3 0-amino acid H O 8-Fluoroadenine Cl OH CH3 0-amino acid H O 2-Fluoroadenine Cl OH CH3 0-amino acid H O 2, 8-Difluoroadenine Cl OH CH3 0-amino acid H 0 2-Fluorohypoxanthine Cl OH CH3 O-amino acid H O 8-Fluorohypoxanthine Cl OH CH3 O-amino acid H O 2, 8-Difluorohypoxanthine Cl OH CH3 O-amino acid H O 2-Aminoadenine Cl OH CH3 0-amino acid H O 2-Amino-8-fluoroadenine Cl OH CH3 0-amino acid H O 2-Amino-8-fluorohypoxanthine Cl OH CH3 O-amino acid H O 2-Aminohypoxanthine C1 OH CH3 O-amino acid H O 2-N-acetylguanine Cl OH F R'T X Base R R CH3 0-amino acid H 0 4-N-acetylcytosine Cl OH CH3 O-amino acid H O 6-N-acetyladenine Cl OH CH3 0-amino acid H 0 2-N-acetyl--fluoroguanine Cl OH CH3 O-amino acid H O 4-N-acetyl-5-fluorocytosine C1 OH CH3 O-amino acid H O 6-N-acetyl-2-fluoroadenine Cl OH CH3 O-amino acid H O 6-N-acetyl-2, 8-difluoroadenine Cl OH CH3 O-amino acid H O 6-N-acetyl-2-aminoadenine Cl OH CH3 O-amino acid H O 6-N-acetyl-2-amino-8-fluoroadenine Cl OH CH3 0-amino acid H O 2-N-acetylaminoadenine Cl OH CH3 0-amino acid H O 2-N-acetylamino-8-fluoroadenine Cl OH CH3 O-amino acid H O 2-N-acetylamino-8-fluorohypoxanthine Cl OH CH3 0-amino acid H O 2-N-acetylaminohypoxanthine Cl OH CH3 O-amino acid H O Thymine H H CH3 O-amino acid H O Uracil H H CH3 0-amino acid H O Guanine H H CH3 O-amino acid H O Cytosine H H CH3 O-amino acid H O Adenine H H CH3 0-amino acid H O Hypoxanthine H H CH3 O-amino acid H O 5-Fluorouracil H H CH3 O-amino acid H O 8-Fluoroguanine H H CH3 O-amino acid H O 5-Fluorocytosine H H CH3 O-amino acid H O 8-Fluoroadenine H H CH3 O-amino acid H O 2-Fluoroadenine H H CH3 O-amino acid H O 2, 8-Difluoroadenine H H CH3 O-amino acid H O 2-Fluorohypoxanthine H H CH3 O-amino acid H O 8-Fluorohypoxanthine H H CH3 O-amino acid H O 2, 8-Difluorohypoxanthine H H CH3 0-amino acid H O 2-Aminoadenine H H CH3 O-amino acid H O 2-Amino-8-fluoroadenine H H CH3 0-amino acid H O 2-Amino-8-fluorohypoxanthine H H CH3 0-amino acid H O 2-Aminohy oxanthine H H CH3 O-amino acid H O 2-N-acetyl guanine H H CH3 O-amino acid H O 4-N-acetylcytosine H H CH3 O-amino acid H O 6-N-acetyladenine H H CH3 O-amino acid H O 2-N-acetyl-8-fluoroguanine H H CH3 0-amino acid H O 4-N-acetyl-5-fluorocytosine H H CH3 0-amino acid H O 6-N-acetyl-2-fluoroadenine H H CH3 0-amino acid H O 6-N-acetyl-2, 8-difluoroadenine H H CH3 0-amino acid H O 6-N-acetyl-2-aminoadenine H H CH3 0-amino acid H O 6-N-acet l-2-amino-8-fluoroadenine H H CH3 0-amino acid H O 2-N-acetylaminoadenine H H CH3 0-amino acid H O 2-N-acetylamino-8-fluoroadenine H H CH3 O-amino acid H O 2-N-acetylamino-8-fluorohypoxanthine H H CH3 O-amino acid H 0 2-N-acetylaminohypoxanthine H H CH3 O-amino acid H O Thymine H 0-amino acid CH3 O-amino acid H O Uracil H O-amino acid CH3 0-amino acid H O Guanine H O-amino acid R° R R X Base R R CH3 0-amino acid H 0 Cytosine H 0-amino acid CH3 0-amino acid H 0 Adenine H 0-amino acid CH3 O-amino acid H O H oxanthine H 0-amino acid CH3 0-amino acid H O 5-Fluorouracil H 0-amino acid CH3 0-amino acid H 0 8-Fluoroguanine H 0-amino acid CH3 0-amino acid H 0 5-Fluorocytosine H 0-amino acid CH3 0-amino acid H O 8-Fluoroadenine H 0-amino acid CH3 O-amino acid H O 2-Fluoroadenine H 0-amino acid CH3 0-amino acid H 0 2, 8-Difluoroadenine H 0-amino acid CH3 0-amino acid H 0 2-Fluorohypoxanthine H 0-amino acid CH3 0-amino acid H O 8-Fluorohypoxanthine H O-amino acid CH3 0-amino acid H 0 2, 8-Difluorohypoxanthine H O-amino acid CH3 0-amino acid H0 2-AminoadenineH0-amino acid CH3 0-amino acid H O 2-Amino-8-fluoroadenine H 0-amino acid CH3 0-amino acid H O 2-Amino-8-fluorohypoxanthine H O-amino acid CH3 0-amino acid H 0 2-Aminohypoxanthine H 0-amino acid CH3 0-amino acid H 0 2-N-acetylguanine H 0-amino acid CH3 0-amino acid H 0 4-N-acetylcytosine H 0-amino acid CH3 0-amino acid H O 6-N-acetyladenine H 0-amino acid CH3 0-amino acid H O 2-N-acetyl-8-fluoroguanine H 0-amino acid CH3 0-amino acid H O 4-N-acetyl-5-fluorocytosine H 0-amino acid CH3 0-amino acid H O 6-N-acetyl-2-fluoroadenine H O-amino acid CH3 0-amino acid H 0 6-N-acetyl-2, 8-difluoroadenine H 0-amino acid CH3 0-amino acid H O 6-N-acetyl-2-aminoadenine H 0-amino acid CH3 0-amino acid H 0 6-N-acetyl-2-amino-8-fluoroadenine H 0-amino acid CH3 0-amino acid H 0 2-N-acetylaminoadenine H 0-amino acid CH3 0-amino acid H O 2-N-acetylamino-8-fluoroadenine H 0-amino acid CH3 0-amino acid H O 2-N-acetylamino-8-fluorohypoxanthine H O-amino acid CH3 0-amino acid H O 2-N-acetyIaminohypoxanthine H 0-amino acid CH3 0-amino acid H O Thymine H O-acyl CH3 0-amino acid H O Uracil H 0-acy1 CH3 0-amino acid H O Guanine H O-acyl CH3 0-amino acid H 10 1 Cytosine H 0-acyl CH3 0-amino acid H O Adenine H 0-acyl CH3 0-amino acid H O H oxanthine H 0-acyl CH3 0-amino acid H O 5-Fluorouracil H 0-acyl CH3 0-amino acid H O 8-Fluoroguanine H 0-acyl CH3 0-amino acid H O 5-Fluorocytosine H 0-acyl CH3 0-amino acid H O 8-Fluoroadenine H O-acy1 CH3 0-amino acid H 0 2-Fluoroadenine H 0-acyl CH3 0-amino acid H 0 2, 8-Difluoroadenine H 0-acyl CH3 0-amino acid H O 2-Fluorohypoxanthine H 0-acyl CH3 0-amino acid H O 8-Fluorohypoxanthine H O-acyl CH3 O-amino acid H O 2, 8-Difluorohypoxanthine H O-acyl CH3 0-amino acid H O 2-Aminoadenine H O-acy1 CH3 0-amino acid H O 2-Amino-8-fluoroadenine H 0-acy1 CH3 0-amino acid H O 2-Amino-8-fluorohypoxanthine H 0-acy1 R R'R X Base R R CH3 O-amino acid H 02-Aminohypoxanthine H 0-acyl CH3 O-amino acid H O 2-N-acetylguanine H O-acyl CH3 O-amino acid H O 4-N-acetylcytosine H O-acyl CH3 O-amino acid H 06-N-acetyladenine H 0-acyl CH3 O-amino acid H O 2-N-acetyl-8-fluoroguanine H O-acyl CH3 0-amino acid H O 4-N-acetyl-5-fluorocytosine H O-acyl CH3 0-amino acid H O 6-N-acetyl-2-fluoroadenine H O-acyl CH3 O-amino acid H O 6-N-acetyl-2, 8-difluoroadenine H O-acyl CH3 O-amino acid H O 6-N-acetyl-2-aminoadenine H O-acyl CH3 O-amino acid H O 6-N-acetyl-2-amino-8-fluoroadenine H O-acyl CH3 O-amino acid H O 2-N-acetylaminoadenine H O-acyl CH3 O-amino acid H O 2-N-acetylamino-8-fluoroadenine H O-acyl CH3 O-amino acid H O 2-N-acetylamino-8-fluorohypoxanthine H O-acyl CH3 0-amino acid H O 2-N-acetylaminohypoxanthine H O-acyl CH3 O-amino acid H O Thymine H OH CH3 O-amino acid H O Uracil H OH CH3 O-amino acid H O Guanine H OH CH3 O-amino acid H O Cytosine H OH CH3 O-amino acid H O Adenine H OH CH3 O-amino acid H O Hypoxanthine _ _ H OH CH3 O-amino acid H O S-Fluorouracil _ H OH CH3 O-amino acid H _ 08-Fluoroguanine H OH CH3 O-amino acid H O 5-Fluorocytosine H OH CH3 O-amino acid H O 8-Fluoroadenine _ H OH CH3 O-amino acid H O 2-Fluoroadenine H OH CH3 O-amino acid H O 2, 8-Difluoroadenine H OH CH3 O-amino acid H 02-Fluorohypoxanthine H OH CH3 O-amino acid H O 8-Fluorohypoxanthine H OH __ CH3 O-amino acid H 02, 8-Difluorohypoxanthine H OH CH3 O-amino acid H O 2-Aminoadenine H OH CH3 O-amino acid H O 2-Amino-8-fluoroadenine H OH CH3 O-amino acid H O 2-Amino-8-fluorohypoxanthine H OH CH3 O-amino acid H 02-Aminohypoxanthine H OH CH3 O-amino acid H O 2-N-acetylguanine H CH3 O-amino acid H O 4-N-acetylcytosine _ H OH CH3 O-amino acid H 06-N-acetyladenine H OH CH3 O-amino acid H 02-N-acetyl-8-fluoroguanine H OH CH3 O-amino acid H O 4-N-acetyl-5-fluorocytosine H OH CH3 O-amino acid H O 6-N-acetyl-2-fluoroadenine H OH CH3 O-amino acid H O 6-N-acetyl-2, 8-difluoroadenine H OH CH3 O-amino acid H O 6-N-acetyl-2-aminoadenine H OH CH3 O-amino acid H O 6-N-acetyl-2-amino-8-fluoroadenine H OH CH3 O-amino acid H O 2-N-acetylaminoadenine H OH CH3 O-amino acid H O 2-N-acetylamino-8-fluoroadenine H OH CH3 O-amino acid H O 2-N-acetylamino-8-fluorohypoxanthine H OH CH3 O-amino acid H 02-N-acetylaminohypoxanthine H OH CH3 O-amino acid H 0. Thymine OH H R6 R7 T X Base R10 R9 CH3 O-amino acid H O Uracil OH H CH3 O-amino acid H O Guanine OH H CH3 0-amino acid H O Cytosine OH H CH3 0-amino acid H O Adenine OH H CH3 O-amino acid H O Hypoxanthine OH H CH3 O-amino acid H O 5-Fluorouracil OH H CH3 O-amino acid H O 8-Fluoroguanine OH H CH3 0-amino acid H O 5-Fluorocytosine OH H CH3 O-amino acid H O 8-Fluoroadenine OH H CH3 O-amino acid H O 2-Fluoroadenine OH H CH3 O-amino acid H O 2, 8-Difluoroadenine OH H CH3 O-amino acid H O 2-Fluorohypoxanthine OH H CH3 O-amino acid H O 8-Fluorohy oxanthine OH H CH3 O-amino acid H O 2, 8-Difluorohypoxanthine OH H CH3 O-amino acid H O 2-Aminoadenine OH H CH3 O-amino acid H O 2-Amino-8-fluoroadenine OH H CH3 0-amino acid H O 2-Amino-8-fluorohypoxanthine OH H CH3 O-amino acid H O 2-Aminohypoxanthine OH H CH3 O-amino acid H O 2-N-acetylguanine OH H CH3 0-amino acid H O 4-N-acetylcytosine OH H CH3 O-amino acid H O 6-N-acetyladenine OH H CH3 O-amino acid H O 2-N-acetyl-8-fluoroguanine OH H CH3 O-amino acid H O 4-N-acetyl-5-fluorocytosine OH H CH3 O-amino acid H O 6-N-acetyl-2-fluoroadenine OH H CH3 O-amino acid H O 6-N-acetyl-2, 8-difluoroadenine OH H CH3 O-amino acid H O 6-N-acetyl-2-aminoadenine OH H CH3 O-amino acid H O 6-N-acetyl-2-amino-8-fluoroadenine OH H CH3 O-amino acid H O 2-N-acetylaminoadenine OH H CH3 O-amino acid H O 2-N-acetylamino-8-fluoroadenine OH H CH3 O-amino acid H O 2-N-acetylamino-8-fluorohypoxanthine OH H CH3 O-amino acid H O 2-N-acetylaminohypoxanthine OH H CH3 OH F O Thymine F O-amino acid CH3 OH F O Uracil F O-amino acid CH3 OH F O Guanine F O-amino acid CH3 OH F O Cytosine F O-amino acid CH3 OH F O Adenine F O-amino acid CH3 OH F O Hypoxanthine F O-amino acid CH3 OH F O 5-Fluorouracil F O-amino acid CH3 OH F O 8-Fluoroguanine F O-amino acid CH3 OH F O 5-Fluorocytosine F O-amino acid CH3 OH F O 8-Fluoroadenine F O-amino acid CH3 OH F O 2-Fluoroadenine F O-amino acid CH3 OH F O 2, 8-Difluoroadenine F O-amino acid CH3 OH F O 2-Fluoroh oxanthine F O-amino acid CH3 OH F O 8-Fluoroh oxanthine F O-amino acid CH3 OH F O 2, 8-Difluorohypoxanthine F O-amino acid CH3 OH F O 2-Aminoadenine F O-amino acid R6 R7 R8 X Base Rl° R9 CH3 OH F O 2-Amino-8-fluoroadenine F O-amino acid CH3 OH F O 2-Amino-8-fluorohypoxanthine F O-amino acid CH3 OH F O 2-Aminohy oxanthine F O-amino acid CH3 OH F O 2-N-acetyl uanine F O-amino acid CH3 OH F O 4-N-acetylcytosine F O-amino acid CH3 OH F 0 6-N-acetyladenine F 0-amino acid CH3 OH F O 2-N-acetyl-8-fluoroguanine F O-amino acid CH3 OH F O 4-N-acetyl-5-fluorocytosine F O-amino acid CH3 OH F O 6-N-acetyl-2-fluoroadenine F O-amino acid CH3 OH F O 6-N-acetyl-2, 8-difluoroadenine F O-amino acid CH3 OH F O 6-N-acetyl-2-aminoadenine F O-amino acid CH3 OH F O 6-N-acetyl-2-amino-8-fluoroadenine F O-amino acid CH3 OH F O 2-N-acetylaminoadenine F O-amino acid CH3 OH F O 2-N-acetylamino-8-fluoroadenine F O-amino acid CH3 OH F O 2-N-acetylamino-8-fluorohypoxanthine F O-amino acid CH3 OH F O 2-N-acetylaminohypoxanthine F 0-amino acid CH3 OH F O Thymine F O-acyl CH3 OH F O Uracil F O-acyl CH3 OH F 0 Guanine F 0-acyl CH3 OH F O Cytosine F O-acyl CH3 OH F 0 Adenine F 0-acyl CH3 OH F O Hypoxanthine F O-acyl CH3 OH F O 5-Fluorouracil F O-acyl CH3 OH F O 8-Fluoroguanine F O-ac 1 CH3 OH F O 5-Fluorocytosine F O-acyl CH3 OH F O 8-Fluoroadenine F O-acyl CH3 OH F O 2-Fluoroadenine F O-acyl CH3 OH F O 2, 8-Difluoroadenine F O-ac 1 CH3 OH F O 2-Fluorohypoxanthine F 0-acyl CH3 OH F O 8-Fluorohypoxanthine F O-acyl CH3 OH F O 2, 8-Difluorohypoxanthine F 0-acyl CH3 OH F 0 2-Aminoadenine F 0-acyl CH3 OH F O 2-Amino-8-fluoroadenine F O-acyl CH3 OH F O 2-Amino-8-fluorohypoxanthine F O-acyl CH3 OH F O 2-Aminohypoxanthine F O-acyl CH3 OH F O 2-N-acetylguanine F O-acyl CH3 OH F O 4-N-acetylcytosine F O-acyl CH3 OH F O 6-N-acetyladenine F O-ac 1 CH3 OH F O 2-N-acetyl-8-fluoroguanine F O-acyl CH3 OH F O 4-N-acetyl-5-fluorocytosine F O-acyl CH3 OH F O 6-N-acetyl-2-fluoroadenine F O-acyl CH3 OH F O 6-N-acetyl-2, 8-difluoroadenine F O-acyl CH3 OH F O 6-N-acetyl-2-aminoadenine F O-acyl CH3 OH F 0 6-N-acetyl-2-amino-8-fluoroadenine F 0-acyl CH3 OH F O 2-N-acet laminoadenine F O-ac 1 CH3 OH F O 2-N-acetylamino-8-fluoroadenine F O-acyl CH3 OH F O 2-N-acetylamino-8-fluorohypoxanthine F O-acyl R6 R7 T X Base Rlo R9 CH3 OH F O 2-N-acetylaminohypoxanthine F O-acyl CH3 OH F O Thymine Br O-amino acid CH3 OH F O Uracil Br O-amino acid CH3 OH F O Guanine Br O-amino acid CH3 OH F O Cytosine Br O-amino acid CH3 OH F O Adenine Br O-amino acid CH3 OH F 0 Hypoxanthine Br 0-amino acid CH3 OH F O 5-Fluorouracil Br O-amino acid CH3 OH F O 8-Fluoro uanine Br O-amino acid CH3 OH F O 5-Fluorocytosine Br O-amino acid CH3 OH F O 8-Fluoroadenine Br O-amino acid CH3 OH F O 2-Fluoroadenine Br O-amino acid CH3 OH F O 2, 8-Difluoroadenine Br O-amino acid CH3 OH F O 2-Fluorohypoxanthine Br O-amino acid CH3 OH F O 8-Fluorohypoxanthine Br O-amino acid CH3 OH F O 2, 8-Difluorohypoxanthine Br O-amino acid CH3 OH F O 2-Aminoadenine Br O-amino acid CH3 OH F O 2-Amino-8-fluoroadenine Br O-amino acid CH3 OH F O 2-Amino-8-fluorohypoxanthine Br O-amino acid CH3 OH F O 2-Aminohypoxanthine Br O-amino acid CH3 OH F O 2-N-acetylguanine Br O-amino acid CH3 OH F O 4-N-acetylcytosine Br O-amino acid CH3 OH F O 6-N-acetyladenine Br O-amino acid CH3 OH F 0 2-N-acetyl-8-fluoroguanine Br 0-amino acid CH3 OH F O 4-N-acetyl-5-fluorocytosine Br O-amino acid CH3 OH F O 6-N-acetyl-2-fluoroadenine Br O-amino acid CH3 OH F O 6-N-acetyl-2, 8-difluoroadenine Br O-amino acid CH3 OH F 0 6-N-acetyl-2-aminoadenine Br 0-amino acid CH3 OH F O 6-N-acetyl-2-amino-8-fluoroadenine Br O-amino acid CH3 OH F O 2-N-acetylaminoadenine Br O-amino acid CH3 OH F O 2-N-acet lamino-8-fluoroadenine Br O-amino acid CH3 OH F O 2-N-acetylamino-8-fluorohypoxanthine Br O-amino acid CH3 OH F 0 2-N-acetylaminohypoxanthine Br 0-amino acid CH3 OH F 0 Thymine Br 0-acyl CH3 OH F O Uracil Br 0-acyl CH3 OH F O Guanine Br O-acyl CH3 OH F O Cytosine Br O-acyl CH3 OH F O Adenine Br O-acyl CH3 OH F 0 Hypoxanthine Br 0-acyl CH3 OH F O 5-Fluorouracil Br O-acyl 3 OH F O 8-Fluoroguanine Br O-acyl CH3 OH F O 5-Fluorocytosine Br O-acyl CH3 OH F O 8-Fluoroadenine Br O-ac 1 CH3 OH F O 2-Fluoroadenine Br O-acyl CH3 OH F O 2, 8-Difluoroadenine Br O-ac 1 CH3 OH F O 2-Fluorohypoxanthine Br O-acyl CH3 OH F O 8-Fluorohypoxanthine Br O-acyl R R R X Base Rlo R9 CH3 OH F O 2, 8-Difluorohypoxanthine Br O-acyl CH3 OH F O 2-Aminoadenine Br O-acyl CH3 OH F 0 2-Amino-8-fluoroadenine Br 0-acyl CH3 OH F 0 2-Amino-8-fluorohypoxanthine Br 0-acyl CH3 OH F 0 2-Aminohypoxanthine Br 0-acyl CH3 OH F O 2-N-acet I uanine Br O-acyl CH3 OH F O 4-N-acetylc osine Br O-ac 1 CH3 OH F O 6-N-acetyladenine Br O-acyI CH3 OH F O 2-N-acet 1-8-fluoroguanine Br O-ac 1 CH3 OH F O 4-N-acetyl-5-fluorocytosine Br O-acyl CH3 OH F 0 6-N-acetyl-2-fluoroadenine Br 0-acyl CH3 OH F O 6-N-acetyl-2, 8-difluoroadenine Br O-acyl CH3 OH F O 6-N-acetyl-2-aminoadenine Br O-acyl CH3 OH F O 6-N-acetyl-2-amino-8-fluoroadenine Br 0-acyl CH3 OH F O 2-N-acetylaminoadenine Br O-acyl CH3 OH F O 2-N-acetylamino-8-fluoroadenine Br O-acyl CH3 OH F O 2-N-acetylamino-8-fluorohypoxanthine Br O-acyl CH3 OH F O 2-N-acetylaminohypoxanthine Br O-acyl CH3 OH F O Thymine Cl O-amino acid CH3 OH F O Uracil Cl O-amino acid CH3 OH F O Guanine Cl O-amino acid CH3 OH F O Cytosine Cl O-amino acid CH3 OH F O Adenine Cl O-amino acid CH3 OH F O Hypoxanthine Cl O-amino acid CH3 OH F O 5-Fluorouracil Cl O-amino acid CH3 OH F O 8-Fluoro uanine C1 O-amino acid CH3 OH F O 5-Fluorocytosine Cl O-amino acid CH3 OH F O 8-Fluoroadenine Cl O-amino acid CH3 OH F O 2-Fluoroadenine Cl O-amino acid CH3 OH F O 2, 8-Difluoroadenine Cl O-amino acid CH3 OH F O 2-Fluorohypoxanthine Cl O-amino acid CH3 OH F 0 8-Fluorohypoxanthine Cl 0-amino acid CH3 OH F O 2, 8-Difluorohypoxanthine CI O-amino acid CH3 OH F O 2-Aminoadenine Cl O-amino acid CH3 OH F 0 2-Amino-8-fluoroadenine Cl 0-amino acid CH3 OH F 0 2-Amino-8-fluorohypoxanthine Cl 0-amino acid CH3 OH F O 2-Aminohypoxanthine Cl O-amino acid CH3 OH F 0 2-N-acetyl guanine Cl 0-amino acid CH3 OH F O 4-N-acetylcytosine Cl O-amino acid CH3 OH F O 6-N-acetyladenine Cl O-amino acid CH3 OH F O 2-N-acetyl-8-fluoroguanine Cl O-amino acid CH3 OH F O 4-N-acetyl-S-fluorocytosine Cl O-amino acid CH3 OH F O 6-N-acet 1-2-fluoroadenine CI O-amino acid CH3 OH F O 6-N-acetyl-2, 8-difluoroadenine CI O-amino acid CH3 OH F O 6-N-acetyl-2-aminoadenine Cl O-amino acid CH3 OH F O 6-N-acetyl-2-amino-8-fluoroadenine Cl O-amino acid CH3 F 0-N-acetylaminoadenine R R7 T X Base w R9 CH3 OH F O 2-N-acetylamino-8-fluoroadenine Cl O-amino acid CH3 OH F O 2-N-acetylamino-8-fluorohypoxanthine Cl O-amino acid CH3 OH F O 2-N-acetylaminohypoxanthine C1 O-amino acid CH3 OH F O Thymine Cl O-acyl CH3 OH F 0 Uracil Cl 0-acyl CH3 OH F 0 Guanine Cl 0-acyl CH3 OH F O Cytosine Cl O-acyl CH3 OH F O Adenine Cl O-acyl CH3 OH F O Hypoxanthine Cl O-acyl CH3 OH F O 5-Fluorouracil C1 O-ac 1 CH3 OH F O 8-Fluoroguanine Cl O-acyl CH3 OH F O 5-Fluorocytosine Cl O-acyl CH3 OH F O 8-Fluoroadenine Cl O-acyl CH3 OH F O 2-Fluoroadenine Cl O-acyl CH3 OH F O 2, 8-Difluoroadenine Cl O-acyl CH3 OH F 0 2-Fluorohypoxanthine Cl 0-acyl CH3 OH F O 8-Fluorohypoxanthine Cl O-acyl CH3 OH F O 2, 8-Difluorohypoxanthine Cl O-acyl CH3 OH F O 2-Aminoadenine Cl O-acyl CH3 OH F O 2-Amino-8-fluoroadenine Cl 0-acyl CH3 OH F O 2-Amino-8-fluorohypoxanthine Cl O-acyl CH3 OH F O 2-Aminohypoxanthine Cl O-acyl CH3 OH F O 2-N-acetylguanine Cl O-acyl CH3 OH F O 4-N-acetylcytosine CI O-acyl CH3 OH F O 6-N-acetyladenine Cl O-acyl CH3 OH F 0 2-N-acetyl-8-fluoroguanine Cl 0-acyl CH3 OH F O 4-N-acetyl-5-fluorocytosine C1 O-acyl CH3 OH F O 6-N-acetyl-2-fluoroadenine CI O-acy1 CH3 OH F O 6-N-acetyl-2, 8-difluoroadenine Cl O-acy1 CH3 OH F O 6-N-acetyl-2-aminoadenine Cl O-acyl CH3 OH F O 6-N-acetyl-2-amino-8-fluoroadenine Cl O-acy1 CH3 OH F O 2-N-acetylaminoadenine Cl O-acyl CH3 OH F O 2-N-acetylamino-8-fluoroadenine Cl O-acyl CH3 OH F O 2-N-acetylamino-8-fluorohypoxanthine Cl O-acy1 CH3 OH F O 2-N-acetylaminohy oxanthine C1 O-acyl CH3 OH F O Thymine H O-amino acid CH3 OH F O Uracil H O-amino acid CH3 OH F O Guanine H O-amino acid CH3 OH F O Cytosine H O-amino acid CH3 OH F O Adenine H O-amino acid CH3 OH F 0 Hypoxanthine H 0-amino acid CH3 OH F O 5-Fluorouracil H O-amino acid CH3 OH F O 8-Fluoroguanine H O-amino acid CH3 OH F O 5-Fluoroc osine H O-amino acid CH3 OH F O 8-Fluoroadenine H O-amino acid CH3 OH F O 2-Fluoroadenine H O-amino acid CH3 OH F O 2, 8-Difluoroadenine H O-amino acid T R7 T X Base w R9 CH3 OH F O 2-Fluorohypoxanthine H 0-amino acid CH3 OH F O 8-Fluorohypoxanthine H O-amino acid CH3 OH F O 2, 8-Difluorohypoxanthine H 0-amino acid CH3 OH F O 2-Aminoadenine H O-amino acid CH3 OH F O 2-Amino-8-fluoroadenine H O-amino acid CH3 OH F 0 2-Amino-8-fluorohypoxanthine H 0-amino acid CH3 OH F O 2-Aminohypoxanthine H O-amino acid CH3 OH F O 2-N-acetylguanine H O-amino acid CH3 OH F O 4-N-acet lc osine H O-amino acid CH3 OH F 0 6-N-acetyladenine H 0-amino acid CH3 OH F 0 2-N-acetyl-8-fluoroguanine H 0-amino acid CH3 OH F O 4-N-acetyl-5-fluorocytosine H O-amino acid CH3 OH F O 6-N-acetyl-2-fluoroadenine H O-amino acid CH3 OH F O 6-N-acetyl-2, 8-difluoroadenine H O-amino acid CH3 OH F O 6-N-acetyl-2-aminoadenine H O-amino acid CH3 OH F O 6-N-acetyl-2-amino-8-fluoroadenine H 0-amino acid CH3 OH F O 2-N-acetylaminoadenine H O-amino acid CH3 OH F O 2-N-acetylamino-8-fluoroadenine H O-amino acid CH3 OH F O 2-N-acetylamino-8-fluorohypoxanthine H O-amino acid CH3 OH F 0 2-N-acetylaminohypoxanthine H 0-amino acid CH3 OH F O Thymine H O-acyl CH3 OH F O Uracil H O-acyl CH3 OH F O Guanine H O-acyl CH3 OH F O Cytosine H O-acyl CH3 OH F O Adenine H O-acyl CH3 OH F O Hypoxanthine H O-acyl CH3 OH F O 5-Fluorouracil H O-acyl CH3 OH F O 8-Fluoroguanine H O-acyl CH3 OH F O 5-Fluorocytosine H O-acyl CH3 OH F O 8-Fluoroadenine H O-acyl CH3 OH F O 2-Fluoroadenine H O-acyl CH3 OH F O 2, 8-Difluoroadenine H O-acyl CH3 OH F O 2-Fluorohypoxanthine H O-acyl CH3 OH F O 8-Fluoroh oxanthine H O-ac 1 CH3 OH F O 2, 8-Difluorohypoxanthine H 0-acyl CH3 OH F O 2-Aminoadenine H O-acyl CH3 OH F O 2-Amino-8-fluoroadenine H O-acyl CH3 OH F O 2-Amino-8-fluorohypoxanthine H O-acyl CH3 OH F 0 2-Aminohypoxanthine H 0-acyl CH3 OH F O 2-N-acetylguanine H O-acyl CH3 OH F O 4-N-acet lcytosine H O-acyl CH3 OH F O 6-N-acetyladenine H O-acyl CH3 OH F O 2-N-acetyl-8-fluoroguanine H O-acyl CH3 OH F O 4-N-acetyl-5-fluorocytosine H O-acyl CH3 OH F O 6-N-acetyl-2-fluoroadenine H O-acyl CH3 OH F O 6-N-acet 1-2, 8-difluoroadenine H O-acyl CH3 OH F 0 6-N-acetyl-2-aminoadenine H 0-acyl R6 R7 R8 X Base F R9 CH3 OH F 0 6-N-acetyl-2-amino-8-fluoroadenine H 0-acyl CH3 OH F O 2-N-acetylaminoadenine H O-acyl CH3 OH F O 2-N-acetylamino-8-fluoroadenine H O-acyl CH3 OH F O 2-N-acetylamino-8-fluorohypoxanthine H O-acyl CH3 OH F O 2-N-acetylaminohypoxanthine H O-acyl CH3 OH Br O Thymine F O-amino acid CH3 OH Br O Uracil F O-amino acid CH3 OH Br O Guanine F O-amino acid CH3 OH Br O Cytosine F O-amino acid CH3 OH Br O Adenine F O-amino acid CH3 OH Br O Hypoxanthine F O-amino acid CH3 OH Br O 5-Fluorouracil F O-amino acid CH3 OH Br O 8-Fluoroguanine F O-amino acid CH3 OH Br O 5-Fluorocytosine F O-amino acid CH3 OH Br O 8-Fluoroadenine F O-amino acid CH3 OH Br O 2-Fluoroadenine F O-amino acid CH3 OH Br O 2, 8-Difluoroadenine F O-amino acid CH3 OH Br O 2-Fluoroh oxanthine F O-amino acid CH3 OH Br O 8-Fluorohypoxanthine F O-amino acid CH3 OH Br O 2, 8-Difluorohypoxanthine F O-amino acid CH3 OH Br O 2-Aminoadenine F O-amino acid CH3 OH Br O 2-Amino-8-fluoroadenine F O-amino acid CH3 OH Br O 2-Amino-8-fluorohypoxanthine F O-amino acid CH3 OH Br O 2-Aminohypoxanthine F O-amino acid CH3 OH Br O 2-N-acetylguanine F O-amino acid CH3 OH Br O 4-N-acetylcytosine F O-amino acid CH3 OH Br O 6-N-acet ladenine F O-amino acid CH3 OH Br O 2-N-acetyl-8-fluoroguanine F O-amino acid CH3 OH Br O 4-N-acetyl-5-fluorocytosine F O-amino acid CH3 OH Br O 6-N-acetyl-2-fluoroadenine F O-amino acid CH3 OH Br O 6-N-acetyl-2, 8-difluoroadenine F O-amino acid CH3 OH Br O 6-N-acet 1-2-aminoadenine F O-amino acid CH3 OH Br O 6-N-acetyl-2-amino-8-fluoroadenine F O-amino acid CH3 OH Br O 2-N-acetylaminoadenine F O-amino acid CH3 OH Br O 2-N-acetylamino-8-fluoroadenine F O-amino acid CH3 OH Br O 2-N-acetylamino-8-fluorohypoxanthine F O-amino acid CH3 OH Br O 2-N-acetylaminohypoxanthine F O-amino acid CH3 OH Br O Thymine F O-acyl CH3 OH Br O Uracil F O-acyl CH3 OH Br O Guanine F O-acyl CH3 OH Br O Cytosine F O-acyl CH3 OH Br O Adenine F O-acyl CH3 OH Br 0 Hypoxanthine F 0-acyl CH3 OH Br O 5-Fluorouracil F O-acyl CH3 OH Br O 8-Fluoroguanine F O-acyl CH3 OH Br O 5-Fluorocytosine F O-acyl CH3 OH Br O 8-Fluoroadenine F O-acyl R R'R X Base R R CH3 OH Br O 2-Fluoroadenine F O-acyl CH3 OH Br O 2, 8-Difluoroadenine F O-acyl CH3 OH Br O 2-Fluorohypoxanthine F O-acyl CH3 OH Br O 8-Fluorohypoxanthine F O-acyl CH3 OH Br O 2, 8-Difluorohypoxanthine F O-acyl CH3 OH Br 0 2-Aminoadenine F 0-acyl CH3 OH Br 0 2-Amino-8-fluoroadenine F 0-acyl CH3 OH Br O 2-Amino-8-fluorohy oxanthine F O-ac 1 CH3 OH Br 0 2-Aminohypoxanthine F 0-acyl CH3 OH Br O 2-N-acetylguanine F O-acyl CH3 OH Br O 4-N-acetylcytosine F O-acyl CH3 OH Br O 6-N-acetyladenine F O-acyl CH3 OH Br O 2-N-acetyl-8-fluoroguanine F O-acyl CH3 OH Br O 4-N-acetyl-5-fluorocytosine F O-acyl CH3 OH Br 0 6-N-acetyl-2-fluoroadenine F 0-acyl CH3 OH Br O 6-N-acetyl-2, 8-difluoroadenine F O-acyl CH3 OH Br O 6-N-acetyl-2-aminoadenine F O-acyl CH3 OH Br O 6-N-acetyl-2-amino-8-fluoroadenine F O-acyl CH3 OH Br O 2-N-acetylaminoadenine F O-acyl CH3 OH Br O 2-N-acetylamino-8-fluoroadenine F O-acyl CH3 OH Br O 2-N-acetylamino-8-fluorohypoxanthine F O-acyl CH3 OH Br O 2-N-acetylaminohypoxanthine F O-acyl CH3 OH Br O Thymine Br O-amino acid CH3 OH Br O Uracil Br O-amino acid CH3 OH Br O Guanine Br O-amino acid CH3 OH Br O Cytosine Br O-amino acid CH3 OH Br O Adenine Br O-amino acid CH3 OH Br O Hypoxanthine Br O-amino acid CH3 OH Br O 5-Fluorouracil Br O-amino acid CH3 OH Br O 8-Fluoroguanine Br O-amino acid CH3 OH Br O 5-Fluorocytosine Br O-amino acid CH3 OH Br O 8-Fluoroadenine Br O-amino acid CH3 OH Br O 2-Fluoroadenine Br O-amino acid CH3 OH Br O 2, 8-Difluoroadenine Br O-amino acid CH3 OH Br O 2-Fluorohypoxanthine Br O-amino acid CH3 OH Br O 8-Fluorohypoxanthine Br O-amino acid CH3 OH Br O 2, 8-Difluorohypoxanthine Br O-amino acid CH3 OH Br O 2-Aminoadenine Br O-amino acid CH3 OH Br O 2-Amino-8-fluoroadenine Br O-amino acid CH3 OH Br 0 2-Amino-8-fluorohypoxanthine Br 0-amino acid CH3 OH Br O 2-Aminohypoxanthine Br O-amino acid CH3 OH Br 0 2-N-acetylguanine Br 0-amino acid CH3 OH Br O 4-N-acetylcytosine Br O-amino acid CH3 OH Br O 6-N-acetyladenine Br O-amino acid CH3 OH Br O 2-N-acetyl-8-fluoroguanine Br O-amino acid CH3 OH Br O 4-N-acetyl-5-fluorocytosine Br O-amino acid CH3 OH Br O 6-N-acetyl-2-fluoroadenine Br O-amino acid R R R X Base R R CH3 OH Br 0 6-N-acetyl-2, 8-difluoroadenine Br O-amino acid CH3 OH Br A 6-N-acetyl-2-aminoadenine Br O-amino acid CH3 OH Br 0 6-N-acetyl-2-amino-8-fluoroadenine Br 0-amino acid CH3 OH Br 0 2-N-acetylaminoadenine Br 0-amino acid CH3 OH Br O 2-N-acetylamino-8-fluoroadenine Br O-amino acid CH3 OH Br O 2-N-acetylamino-8-fluorohypoxanthine Br O-amino acid CH3 OH Br 0 2-N-acetylaminohypoxanthine Br O-amino acid CH3 OH Br 0 Thymine Br 0-acyl CH3 OH Br O Uracil Br O-acyl CH3 OH Br O Guanine Br O-acyl CH3 OH Br 0 Cytosine Br 0-acyl CH3 OH Br 0 Adenine Br 0-acyl CH3 OH Br 0 Hypoxanthine Br 0-acyl CH3 OH Br 0 5-Fluorouracil Br O-acyl CH3 OH Br 0 8-Fluoroguanine Br 0-acyl CH3 OH Br 0 5-Fluorocytosine Br 0-acyl CH3 OH Br 0 8-Fluoroadenine Br 0-acyl CH3 OH Br O 2-Fluoroadenine Br O-acyl CH3 OH Br 0 2, 8-Difluoroadenine Br 0-acyl CH3 OH Br 0 2-Fluorohypoxanthine Br O-acyl CH3 OH Br 0 8-Fluorohypoxanthine Br O-acyl CH3 OH Br 0 2, 8-Difluorohypoxanthine Br O-acyl CH3 OH Br O 2-Aminoadenine Br O-acyl CH3 OH Br 0 2-Amino-8-fluoroadenine Br O-acyl CH3 OH Br 0 2-Amino-8-fluorohypoxanthine Br 0-acyl CH3 OH Br 0 2-Aminohypoxanthine Br O-acyl CH3 OH Br S 2-N-acetylguanine Br O-acyl CH3 OH Br O 4-N-acetylcytosine Br O-acyl CH3 OH Br S 6-N-acetyladenine Br O-acyl CH3 OH Br 0 2-N-acetyl-8-fluoroguanine Br O-acyl CH3 OH Br O 4-N-acet 1-5-fluoroc osine Br O-ac 1 CH3 OH Br O 6-N-acet 1-2-fluoroadenine Br O-acyl CH3 OH Br 0 6-N-acetyl-2, 8-difluoroadenine Br O-acyl CH3 OH Br O 6-N-acetyl-2-aminoadenine Br 0-acyl CH3 OH Br Q 6-N-acetyl-2-am ino-8-fluoroadenine Br O-acyl CH3 OH Br Q 2-N-acetylaminoadenine Br O-acyl CH3 OH Br O 2-N-acetylamino-8-fluoroadenine Br O-acyl CH3 OH Br 0 2-N-acetylamino-8-fluorohypoxanthine Br O-acyl CH3 OH Br 0 2-N-acetylaminohypoxanthine Br O-acyl CH3 OH Br 0 Thymine Cl 0-amino acid CH3 OH Br 0 Uracil Cl 0-amino acid CH3 OH Br O Guanine Cl O-amino acid CH3 OH Br O Cytosine Cl O-amino acid CH3 OH Br O Adenine Cl O-amino acid CH3 OH Br O Hypoxanthine Cl O-amino acid CH3 OH Br 0 5-Fluorouracil Cl 0-amino acid CH3 OH Br O 8-Fluoroguanine Cl O-amino acid R R R X Base R R' CH3 OH Br O 5-Fluorocytosine Cl O-amino acid CH3 OH Br O 8-Fluoroadenine Cl O-amino acid CH3 OH Br O 2-Fluoroadenine Cl O-amino acid CH3 OH Br O 2, 8-Difluoroadenine Cl O-amino acid CH3 OH Br O 2-Fluorohypoxanthine C1 O-amino acid CH3 OH Br O 8-Fluorohypoxanthine Cl O-amino acid CH3 OH Br O 2, 8-Difluorohypoxanthine Cl O-amino acid CH3 OH Br O 2-Aminoadenine Cl O-amino acid CH3 OH Br O 2-Amino-8-fluoroadenine Cl O-amino acid CH3 OH Br O 2-Amino-8-fluorohypoxanthine Cl O-amino acid CH3 OH Br O 2-Aminoh oxanthine C1 O-amino acid CH3 OH Br 0 2-N-acetyl guanine Cl 0-amino acid CH3 OH Br O 4-N-acetylcytosine Cl O-amino acid CH3 OH Br O 6-N-acetyladenine Cl O-amino acid CH3 OH Br O 2-N-acetyl-8-fluoroguanine Cl O-amino acid CH3 OH Br O 4-N-acetyl-5-fluorocytosine Cl O-amino acid CH3 OH Br O 6-N-acetyl-2-fluoroadenine Cl O-amino acid CH3 OH Br O 6-N-acetyl-2, 8-difluoroadenine Cl O-amino acid CH3 OH Br O 6-N-acetyl-2-am inoadenine Cl O-amino acid CH3 OH Br 0 6-N-acetyl-2-amino-8-fluoroadenine Cl 0-amino acid CH3 OH Br O 2-N-acetylaminoadenine Cl O-amino acid CH3 OH Br O 2-N-acetylamino-8-fluoroadenine Cl O-amino acid CH3 OH Br O 2-N-acetylamino-8-fluorohypoxanthine Cl O-amino acid CH3 OH Br 0 2-N-acetylaminohypoxanthine Cl O-amino acid CH3 OH Br 0 Thymine Cl O-acyl CH3 OH Br O Uracil Cl O-acyl CH3 OH Br 0 Guanine Cl 0-acyl CH3 OH Br O Cytosine Cl O-acyl CH3 OH Br 0 Adenine Cl 0-acyl CH3 OH Br 0 Hypoxanthine Cl 0-acyl CH3 OH Br O 5-Fluorouracil Cl O-acy1 CH3 OH Br O 8-Fluoroguanine Cl O-acyl CH3 OH Br 0 5-Fluorocytosine Cl O-acyl CH3 OH Br O 8-Fluoroadenine Cl O-acyl CH3 OH Br O 2-Fluoroadenine Cl O-acyl CH3 OH Br O 2, 8-Difluoroadenine Cl O-acyl CH3 OH Br O 2-Fluorohypoxanthine Cl O-acyl CH3 OH Br O 8-Fluorohypoxanthine Cl O-acyl CH3 OH Br O 2, 8-Difluorohy oxanthine CI O-acyl CH3 OH Br O 2-Aminoadenine CI O-ac 1 CH3 OH Br O 2-Amino-8-fluoroadenine Cl O-acyl CH3 OH Br O 2-Amino-8-fluorohypoxanthine Cl O-acyl CH3 OH Br O 2-Aminohy oxanthine C1 O-acyl CH3 OH Br O 2-N-acetyl uanine Cl O-acyl CH3 OH Br 0 4-N-acetylcytosine CI O-acyl CH3 OH Br O 6-N-acet ladenine C1 O-ac 1 CH3 OH Br 0 2-N-acetyl-8-fluoroguanine Cl O-acyl R R 8 X Base R R CH3 OH Br O 4-N-acet 1-5-fluorocytosine Cl O-acyl CH3 OH Br O 6-N-acetyl-2-fluoroadenine Cl O-acyl CH3 OH Br O 6-N-acetyl-2, 8-difluoroadenine Cl O-acyl CH3 OH Br O 6-N-acetyl-2-aminoadenine Cl O-acyl CH3 OH Br 0 6-N-acetyl-2-amino-8-fluoroadenine Cl 0-acyl CH3 OH Br 0 2-N-acetylaminoadenine Cl O-acyl CH3 OH Br O 2-N-acetylamino-8-fluoroadenine C1 O-ac 1 CH3 OH Br 0 2-N-acetylamino-8-fluorohypoxanthine Cl O-acyl CH3 OH Br 0 2-N-acetylaminohypoxanthine Cl O-acyl CH3 OH Br 0 Thymine H 0-amino acid CH3 OH Br A Uracil H O-amino acid CH3 OH Br 0 Guanine H 0-amino acid CH3 OH Br 0 Cytosine H O-amino acid CH3 OH Br 0 Adenine H 0-amino acid CH3 OH Br 0 Hypoxanthine H O-amino acid CH3 OH Br 0 5-Fluorouracil H 0-amino acid CH3 OHBr 0 8-F ! uoroguanineH0-amino acid CH3 OH Br O 5-Fluorocytosine H O-amino acid CH3 OH Br O 8-Fluoroadenine H O-amino acid CH3 OH Br O 2-Fluoroadenine H O-amino acid CH3 OH Br O 2, 8-Difluoroadenine H O-amino acid CH3 OH Br 0 2-Fluorohypoxanthine H 0-amino acid CH3 OH Br 0 8-Fluorohypoxanthine H 0-amino acid CH3 OH Br O 2, 8-Difluorohypoxanthine H O-amino acid CH3 OH Br O 2-Aminoadenine H O-amino acid CH3 OH Br O 2-Amino-8-fluoroadenine H O-amino acid CH3 OH Br O 2-Amino-8-fluorohypoxanthine H O-amino acid CH3 OH Br 0 2-Aminohypoxanthine H 0-amino acid CH3 OH Br 0 2-N-acetylguanine H 0-amino acid CH3 OH Br Q 4-N-acetylcytosine H O-amino acid CH3 OH Br O 6-N-acetyladenine H O-amino acid CH3 OH Br 0 2-N-acetyl-8-fluoroguanine H O-amino acid CH3 OH Br 0 4-N-acetyl-5-fluorocytosine H O-amino acid CH3 OH Br O 6-N-acetyl-2-fluoroadenine H O-amino acid CH3 OH Br O 6-N-acetyl-2, 8-difluoroadenine H O-amino acid CH3 OH Br O 6-N-acetyl-2-aminoadenine H O-amino acid CH3 OH Br O 6-N-acet 1-2-amino-8-fluoroadenine H O-amino acid CH3 OH Br O 2-N-acetylaminoadenine H O-amino acid CH3 OH Br O 2-N-acetylamino-8-fluoroadenine H O-amino acid CH3 OH Br 0 2-N-acetylamino-8-fluorohypoxanthine H 0-amino acid CH3 OH Br 0 2-N-acetylaminohypoxanthine H 0-amino acid CH3 OH Br O Thymine H O-acyl CH3 OH Br 0 Uracil H O-acyl CH3 OH Br 0 Guanine H 0-acyl CH3 OH Br 0 Cytosine H-acyl CH3 OH Br O Adenine H O-acyl CH3 OH Br O Hypoxanthine H O-acyl R R R X Base Rlo R9 CH3 OH Br O 5-Fluorouracil H O-acyl CH3 OH Br O 8-Fluoroguanine H O-acyl CH3 OH Br O 5-Fluorocytosine H O-acyl CH3 OH Br O 8-Fluoroadenine H O-acyl CH3 OH Br O 2-Fluoroadenine H O-acyl CH3 OH Br O 2, 8-Difluoroadenine H 0-acyl CH3 OH Br O 2-Fluorohypoxanthine H O-acyl CH3 OH Br O 8-Fluorohypoxanthine H O-acyl CH3 OH Br O 2, 8-Difluorohypoxanthine H O-acyl CH3 OH Br O 2-Aminoadenine H O-acyl CH3 OH Br O 2-Amino-8-fluoroadenine H O-acyl CH3 OH Br 0 2-Amino-8-fluorohypoxanthine H 0-acyl CH3 OH Br 0 2-Aminohypoxanthine H 0-acyl CH3 OH Br O 2-N-acetylguanine H O-acyl CH3 OH Br O 4-N-acetylcytosine H O-acyl CH3 OH Br O 6-N-acetyladenine H O-acyl CH3 OH Br O 2-N-acetyl-8-fluoroguanine H O-acyl CH3 OH Br 0 4-N-acetyl-5-fluorocytosine H 0-acyl CH3 OH Br O 6-N-acetyl-2-fluoroadenine H O-acyl CH3 OH Br O 6-N-acetyl-2, 8-difluoroadenine H O-acyl CH3 OH Br O 6-N-acetyl-2-aminoadenine H O-acyl CH3 OH Br 0 6-N-acetyl-2-amino-8-fluoroadenine H 0-acyl CH3 OH Br O 2-N-acetylaminoadenine H O-acyl CH3 OH Br O 2-N-acetylamino-8-fluoroadenine H O-acyl CH3 OH Br O 2-N-acetylamino-8-fluorohypoxanthine H 0-acyl CH3 OH Br 0 2-N-acetylaminohypoxanthine H 0-acyl CH3 OH Cl O Thymine F 0-amino acid CH3 OH Cl O Uracil F O-amino acid CH3 OH Cl O Guanine F O-amino acid CH3 OH Cl O Cytosine F O-amino acid CH3 OH Cl O Adenine F O-amino acid CH3 OH Cl O Hypoxanthine F O-amino acid CH3 OH Cl O 5-Fluorouracil F O-amino acid CH3 OH Cl O 8-Fluoroguanine F O-amino acid CH3 OH Cl O 5-Fluorocytosine F O-amino acid CH3 OH Cl O 8-Fluoroadenine F O-amino acid CH3 OH Cl O 2-Fluoroadenine F O-amino acid CH3 OH Cl O 2, 8-Difluoroadenine F O-amino acid CH3 OH Cl O 2-Fluorohypoxanthine F O-amino acid CH3 OH CI O 8-Fluorohypoxanthine F O-amino acid CH3 OH Cl O 2, 8-Difluorohypoxanthine F O-amino acid CH3 OH Cl O 2-Aminoadenine F O-amino acid CH3 OH Cl 0 2-Amino-8-fluoroadenine F 0-amino acid CH3 OH Cl O 2-Amino-8-fluorohypoxanthine F O-amino acid CH3 OH Cl O 2-Aminohypoxanthine F 0-amino acid CH3 OH Cl O 2-N-acetylguanine F O-amino acid CH3 OH Cl O 4-N-acetylcytosine F O-amino acid T R7 T X Base Rl° R9 CH3 OH Cl O 6-N-acetyladenine F O-amino acid CH3 OH Cl O 2-N-acetyl-8-fluoroguanine F O-amino acid CH3 OH Cl O 4-N-acety1-5-fluorocytosine F O-amino acid CH3 OH CI O 6-N-acetyl-2-fluoroadenine F O-amino acid CH3 OH Cl O 6-N-acetyl-2, 8-difluoroadenine F O-amino acid CH3 OH Cl O 6-N-acetyl-2-aminoadenine F 0-amino acid CH3 OH Cl O 6-N-acetyl-2-amino-8-fluoroadenine F O-amino acid CH3 OH Cl O 2-N-acetylaminoadenine F O-amino acid CH3 OH Cl O 2-N-acety ino-8-fluoroadenine F O-amino acid CH3 OH Cl O 2-N-acetylamino-8-fluorohypoxanthine F O-amino acid CH3 OH CI O 2-N-acetylaminohypoxanthine F O-amino acid CH3 OH Cl O Thymine F O-acyl CH3 OH Cl O Uracil F O-acyl CH3 OH Cl O Guanine F O-acyl CH3 OH Cl O Cytosine F O-acyl CH3 OH Cl O Adenine F O-acyl CH3 OH Cl O Hypoxanthine F O-acyl CH3 OH Cl O 5-Fluorouracil F O-acyl CH3 OH Cl O 8-Fluoroguanine F O-acyl CH3 OH Cl O 5-Fluorocytosine F O-acyl CH3 OH Cl O 8-Fluoroadenine F O-acyl CH3 OH Cl O 2-Fluoroadenine F O-acyl CH3 OH Cl O 2, 8-Difluoroadenine F O-acyl CH3 OH Cl 0 2-Fluorohypoxanthine F 0-acyl CH3 OH Cl O 8-Fluorohypoxanthine F 0-acyl CH3 OH Cl O 2, 8-Difluorohypoxanthine F 0-acyl CH3 OH C I O 2-Am inoaden ine F O-acyl CH3 OH Cl O 2-Am ino-8-fluoroadenine F O-acyl CH3 OH Cl 0 2-Amino-8-fluorohypoxanthine F 0-acyl CH3 OH Cl O 2-Aminohypoxanthine F O-acyl CH3 OH Cl O 2-N-acetylguanine F 0-acyl CH3 OH Cl O 4-N-acetylcytosine F 0-acyl CH3 OH Cl O 6-N-acetyladenine F O-acyl CH3 OH Cl O 2-N-acetyl-8-fluoroguanine F O-acyl CH3 OH Cl O 4-N-acetyl-5-fluorocytosine F O-acyl CH3 OH Cl O 6-N-acetyl-2-fluoroadenine F O-acyl CH3 OH Cl O 6-N-acetyl-2, 8-difluoroadenine F O-acyl CH3 OH Cl O 6-N-acetyl-2-aminoadenine F 0-acyl CH3 OH Cl O 6-N-acetyl-2-amino-8-fluoroadenine F O-acyl CH3 OH Cl O 2-N-acetylaminoadenine F O-acyl CH3 OH 0 Cl O 2-N-acetylam ino-8-fluoroadenine F O-acyl CH3 OH Cl O 2-N-acetylamino-8-fluorohypoxanthine F O-acyl CH3 OH Cl O 2-N-acetylaminohypoxanthine F O-acyl CH3 OH Cl O Thymine Br 0-amino acid CH3 OH Cl O Uracil Br 0-amino acid 3 OH CI O Guanine Br 0-amino acid CH3 OH Cl O Cytosine Br O-amino acid R6 R 7 R 8 X Base Rlo R9 CH3 OH Cl O Adenine Br O-amino acid CH3 OH Cl 0 Hypoxanthine Br 0-amino acid CH3 OH Cl O 5-Fluorouracil Br O-amino acid CH3 OH Cl O 8-Fluoroguanine Br O-amino acid CH3 OH _ Cl O 5-Fluorocytosine Br O-amino acid CH3 OH Cl O 8-Fluoroadenine Br O-amino acid CH3 OH Cl O 2-Fluoroadenine Br O-amino acid CH3 OH Cl O 2, 8-Difluoroadenine Br O-amino acid CH3 OH Cl O 2-Fluorohypoxanthine Br O-amino acid CH3 OH Cl O 8-Fluorohypoxanthine Br O-amino acid CH3 OH Cl O 2, 8-Difluorohypoxanthine Br O-amino acid CH3 OH Cl O 2-Aminoadenine Br O-amino acid B CH3 OH Cl O 2-Amino-8-fluoroadenine Br O-amino acid CH3 OH Cl O 2-Amino-8-fluorohypoxanthine Br O-amino acid CH3 OH Cl O 2-Aminohy oxanthine Br O-amino acid CH3 OH Cl O 2-N-acetylguanine Br O-amino acid CH3 OH Cl O 4-N-acetylcytosine Br O-amino acid CH3 OH Cl O 6-N-acetyladenine Br O-amino acid CH3 OH Cl O 2-N-acetyl-8-fluoroguanine Br O-amino acid CH3 OH Cl 0 4-N-acetyl-5-fluorocytosine Br 0-amino acid CH3 OH Cl 0 6-N-acetyl-2-fluoroadenine Br 0-amino acid CH3 OH Cl O 6-N-acetyl-2, 8-difluoroadenine Br O-amino acid CH3 OH Cl O 6-N-acetyl-2-aminoadenine Br O-amino acid CH3 OH Cl O 6-N-acetyl-2-amino-8-fluoroadenine Br O-amino acid CH3 OH Cl O 2-N-acetylaminoadenine Br O-amino acid CH3 OH Cl O 2-N-acetylamino-8-fluoroadenine Br O-amino acid CH3 OH Cl O 2-N-acetylamino-8-fluorohypoxanthine Br O-amino acid CH3 OH Cl O 2-N-acetylaminohypoxanthine Br O-amino acid CH3 OH Cl O Thymine Br O-acyl CH3 OH Cl O Uracil Br O-acyl CH3 OH Cl O Guanine Br O-acyl CH3 OH Cl O Cytosine Br O-acyl CH3 OH Cl O Adenine Br O-acyl CH3 OH Cl O Hypoxanthine Br 0-acyl CH3 OH Cl O 5-Fluorouracil Br O-acyl CH3 OH Cl O 8-Fluoroguanine Br O-acyl CH3 OH CI O 5-Fluorocytosine Br O-acyl CH3 OH Cl O 8-Fluoroadenine Br O-acyl CH3 OH Cl O 2-Fluoroadenine Br O-acyl CH3 OH ci 0 2, 8-Difluoroadenine Br 0-acyl CH3 OH CI O 2-Fluoroh oxanthine Br O-acyl CH3 OH Cl O 8-Fluorohypoxanthine Br O-acyl CH3 OH Cl O 2, 8-Difluorohypoxanthine Br O-acyl CH3 OH Cl O 2-Aminoadenine Br O-acyl CH3 OH Cl O 2-Amino-8-fluoroadenine Br O-acyl CH3 OH Cl O 2-Amino-8-fluoroh oxanthine Br O-ac 1 CH3 OH C1 O 2-Aminoh oxanthine Br O-acyl Re R7 R8 X Base Rl° R9 CH3 OH Cl O 2-N-acetylguanine Br O-acyl CH3 OH Cl O 4-N-acetylcytosine Br O-acyl CH3 OH Cl O 6-N-acetyladenine Br O-acyl CH3 OH Cl O 2-N-acetyl-8-fluoroguanine Br O-acyl CH3 OH Cl O 4-N-acetyl-5-fluorocytosine Br O-acyl CH3 OH Cl O b-N-acet I-2-fluoroadenine Br O-ac 1 CH3 OH Cl O 6-N-acetyl-2, 8-difluoroadenine Br O-acyl CH3 OH C1 O 6-N-acet 1-2-aminoadenine Br O-ac 1 CH3 OH Cl O 6-N-acetyl-2-amino-8-fluoroadenine Br 0-acyl CH3 OH Cl O 2-N-acetylaminoadenine Br O-acyl CH3 OH CI O 2-N-acetylamino-8-fluoroadenine Br O-acyl CH3 OH Cl O 2-N-acetylamino-8-fluorohypoxanthine Br O-acyl CH3 OH Cl O 2-N-acetylaminohypoxanthine Br O-acyl CH3 OH Cl O Thymine Cl O-amino acid CH3 OH Cl O Uracil Cl O-amino acid CH3 OH C1 O Guanine Cl O-amino acid CH3 OH Cl O Cytosine Cl O-amino acid CH3 OH Cl O Adenine Cl O-amino acid CH3 OH Cl O Hypoxanthine Cl O-amino acid CH3 OH Cl O 5-Fluorouracil Cl O-am ino acid CH3 OH Cl O 8-Fluoroguanine Cl O-amino acid CH3 OH Cl O 5-Fluorocytosine Cl O-amino acid CH3 OH Cl O 8-Fluoroadenine Cl O-amino acid CH3 OH Cl O 2-Fluoroadenine Cl O-amino acid CH3 OH Cl 0 2, 8-Difluoroadenine Cl O-amino acid CH3 OH Cl O 2-Fluorohy oxanthine Cl O-amino acid CH3 OH Cl O 8-Fluoroh oxanthine C1 O-amino acid CH3 OH C1 O 2, 8-Difluorohy oxanthine CI O-amino acid CH3 OH Cl O 2-Aminoadenine Cl O-amino acid CH3 OH Cl O 2-Amino-8-fluoroadenine Cl O-amino acid CH3 OH Cl O 2-Amino-8-fluorohypoxanthine Cl O-amino acid CH3 OH Cl O 2-Aminohypoxanthine Cl O-amino acid CH3 OH Cl O 2-N-acetylguanine Cl O-amino acid CH3 OH Cl O 4-N-acetylcytosine Cl O-amino acid CH3 OH Cl O 6-N-acetyladenine Cl O-amino acid CH3 OH Cl O 2-N-acetyl-8-fluoroguanine Cl O-amino acid CH3 OH Cl O 4-N-acetyl-5-fluorocytosine Cl O-amino acid CH3 OH Cl O 6-N-acetyl-2-fluoroadenine Cl O-amino acid CH3 OH Cl O 6-N-acetyl-2, 8-difluoroadenine Cl O-amino acid CH3 OH Cl 0 6-N-acetyl-2-aminoadenine Cl O-amino acid CH3 OH Cl O 6-N-acetyl-2-amino-8-fluoroadenine Cl O-amino acid CH3 OH Cl Q 2-N-acetylaminoadenine Cl O-amino acid CH3 OH Cl O 2-N-acetylamino-8-fluoroadenine Cl O-amino acid CH3 OH Cl O 2-N-acetylamino-8-fluorohypoxanthine Cl O-amino acid CH3 OH Cl O 2-N-acetylaminohypoxanthine Cl O-amino acid CH3 OH Cl O Th ine CI O-ac 1 CH3 OH Cl O Uracil Cl O-acyl R6 R7 W X Base R10 R9 CH3 OH Cl O Guanine Cl O-acyl CH3 OH Cl O Cytosine Cl 0-acyl CH3 OH Cl O Adenine Cl O-acyl CH3 OH Cl O Hypoxanthine Cl O-acyl CH3 OH Cl O S-Fluorouracil Cl O-acYI CH3 OH Cl O 8-Fluoroguanine Cl O-acyl CH3 OH Cl O 5-Fluorocytosine Cl 0-acyl CH3 OH Cl O 8-Fluoroadenine Cl O-acyl CH3 OH Cl O 2-Fluoroadenine Cl O-acyl CH3 OH Cl 0 2, 8-Difluoroadenine Cl O-acyl CH3 OH Cl O 2-Fluorohypoxanthine Cl O-acyl CH3 OH Cl O 8-Fluorohypoxanthine Cl O-acyl CH3 OH Cl O 2, 8-Difluorohypoxanthine Cl 0-acyl CH3 OH Cl O 2-Aminoadenine Cl O-acyl CH3 OH Cl O 2-Amino-8-fluoroadenine Cl O-acyl CH3 OH Cl O 2-Amino-8-fluorohypoxanthine Cl O-acyl CH3 OH Cl O 2-Aminohypoxanthine Cl 0-acyl CH3 OH Cl O 2-N-acetylguanine Cl O-acyl CH3 OH Cl O 4-N-acetylcytosine Cl O-acy1 CH3 OH Cl O 6-N-acetyladenine Cl O-acyl CH3 OH Cl O 2-N-acetyl-8-fluoroguanine Cl O-acyl CH3 OH Cl O 4-N-acetyl-5-fluorocytosine Cl O-acyl CH3 OH Cl O 6-N-acetyl-2-fluoroadenine Cl O-acyl CH3 OH CI O 6-N-acetyl-2, 8-difluoroadenine Cl O-acyl CH3 OH Cl O 6-N-acetyl-2-aminoadenine Cl O-acyl CH3 OH Cl O 6-N-acetyl-2-amino-8-fluoroadenine Cl O-acyI CH3 OH Cl O 2-N-acetylaminoadenine Cl O-acyl CH3 OH C1 O 2-N-acetylamino-8-fluoroadenine Cl O-acyl CH3 OH Cl O 2-N-acetylamino-8-fluorohypoxanthine Cl O-acyl CH3 OH Cl O 2-N-acetylaminoh oxanthine Cl O-acyl CH3 OH Cl O Thymine H O-amino acid CH3 OH Cl O Uracil H O-amino acid CH3 OH Cl O Guanine H O-amino acid CH3 OH Cl O Cytosine H O-amino acid CH3 OH Cl O Adenine H O-amino acid CH3 OH Cl O Hypoxanthine H O-amino acid CH3 OH Cl O 5-Fluorouracil H O-amino acid CH3 OH Cl O 8-Fluoroguanine H O-amino acid CH3 OH Cl O 5-Fluorocytosine H O-amino acid CH3 OH ci O 8-Fluoroadenine H O-amino acid CH3 OH Cl O 2-Fluoroadenine H O-amino acid CH3 OH Cl O 2, 8-Difluoroadenine H O-amino acid CH3 OH Cl O 2-Fluorohypoxanthine H O-amino acid CH3 OH Cl O 8-Fluorohypoxanthine H 0-amino acid CH3 OH Cl O 2, 8-Difluorohypoxanthine H 0-amino acid CH3 OH Cl O 2-Aminoadenine H O-amino acid CH3 OH Cl O 2-Amino-8-fluoroadenine H O-amino acid R6 R'R# X Base R R CH3 OH Cl O 2-Amino-8-fluorohypoxanthine H O-amino acid CH3 OH Cl O 2-Aminohypoxanthine H 0-amino acid CH3 OH Cl O 2-N-acetyl guanine H 0-amino acid CH3 OH Cl O 4-N-acetylcytosine H O-amino acid CH3 OH Cl O 6-N-acetyladenine H O-amino acid CH3 OH Cl O 2-N-acet 1-8-fluoroguanine H O-amino acid CH3 OH Cl O 4-N-acetyl-5-fluorocytosine H 0-amino acid CH3 OH Cl O 6-N-acetyl-2-fluoroadenine H 0-amino acid CH3 OH Cl O 6-N-acetyl-2, 8-difluoroadenine H O-amino acid CH3 OH Cl O 6-N-acetyl-2-aminoadenine H O-amino acid CH3 OH Cl O 6-N-acetyl-2-amino-8-fluoroadenine H O-amino acid CH3 OH Cl O 2-N-acetylaminoadenine H O-amino acid CH3 OH C I O 2-N-acetylam ino-8-fluoroadenine H O-amino acid CH3 OH Cl O 2-N-acetylamino-8-fluorohypoxanthine H 0-amino acid CH3 OH Cl O 2-N-acetylaminohypoxanthine H O-amino acid CH3 OH Cl O Thymine H O-acyl CH3 OH Cl O Uracil H O-acyl CH3 OH Cl O Guanine H O-acyl CH3 OH Cl O Cytosine H O-acyl CH3 OH Cl O Adenine H O-acyl CH3 OH Cl O Hypoxanthine H 0-acyl CH3 OH Cl O 5-Fluorouracil H O-acyl CH3 OH Cl O 8-Fluoroguanine H O-acyl CH3 OH Cl O 5-Fluorocytosine H O-acyl CH3 OH Cl O 8-Fluoroadenine H O-acyl CH3 OH Cl O 2-Fluoroadenine H O-acyl CH3 OH Cl O 2, 8-Difluoroadenine H O-acyl CH3 OH Cl O 2-Fluorohy oxanthine H O-ac 1 CH3 OH Cl O 8-Fluorohypoxanthine H O-acyl CH3 OH Cl O 2, 8-Difluorohypoxanthine H O-acyl CH3 OH Cl O 2-Aminoadenine H 0-acyl CH3 OH Cl O 2-Amino-8-fluoroadenine H O-ac 1 CH3 OH Cl O 2-Amino-8-fluorohypoxanthine H O-acyi CH3 OH Cl O 2-Aminohy oxanthine H O-acyl CH3 OH C1 O 2-N-acetylguanine H O-acyl CH3 OH CI O 4-N-acetylcytosine H O-acyl CH3 OH Cl O 6-N-acetyladenine H O-acyl CH3 OH Cl O 2-N-acetyl-8-fluoroguanine H O-acyl CH3 OH Cl O 4-N-acetyl-5-fluorocytosine H O-acyl CH3 OH Cl O 6-N-acetyl-2-fluoroadenine H O-acyl CH3 OH Cl O 6-N-acetyl-2, 8-difluoroadenine H O-acyl CH3 OH Cl O 6-N-acetyl-2-aminoadenine H O-acyl CH3 OH Cl O 6-N-acetyl-2-amino-8-fluoroadenine H O-acyl CH3 OH Cl O 2-N-acetylaminoadenine H O-acyl CH3 OH Cl O 2-N-acetylamino-8-fluoroadenine H O-ac 1 CH3 OH CI O 2-N-acetylamino-8-fluorohypoxanthine H O-acyl CH3 OH Cl O 2-N-acetylaminohypoxanthine H O-acyl R6 R7 T X Base R R9 CH3 OH H O Thymine F O-amino acid CH3 OH H O Uracil F O-amino acid CH3 OH H O Guanine F O-amino acid CH3 OH H O Cytosine F O-amino acid CH3 OH H O Adenine F O-amino acid CH3 OH H O Hypoxanthine F O-amino acid CH3 OH H O 5-Fluorouracil F O-amino acid CH3 OH H O 8-Fluoroguanine F O-amino acid CH3 OH H O 5-Fluorocytosine F 0-amino acid CH3 OH H O 8-Fluoroadenine F O-amino acid CH3 OH H O 2-Fluoroadenine F O-amino acid CH3 OH H O 2, 8-Difluoroadenine F O-amino acid CH3 OH H O 2-Fluorohypoxanthine F 0-amino acid CH3 OH H O 8-Fluorohy oxanthine F O-amino acid CH3 OH H O 2, 8-Difluorohypoxanthine F 0-amino acid CH3 OH H O 2-Aminoadenine F O-amino acid CH3 OH H O 2-Amino-8-fluoroadenine F O-amino acid CH3 OH H O 2-Amino-8-fluoroh oxanthine F O-amino acid CH3 OH H O 2-Aminohypoxanthine F O-amino acid CH3 OH H O 2-N-acetyIguanine F O-amino acid CH3 OH H O 4-N-acetylcytosine F O-amino acid CH3 OH H O 6-N-acetyladenine F O-amino acid CH3 OH H O 2-N-acetyl-8-fluoroguanine F O-amino acid CH3 OH H O 4-N-acetyl-5-fluorocytosine F O-amino acid CH3 OH H O 6-N-acetyl-2-fluoroadenine F O-amino acid CH3 OH H O 6-N-acetyl-2, 8-difluoroadenine F O-amino acid CH3 OH H 0 6-N-acetyl-2-aminoadenine F 0-amino acid CH3 OH H O 6-N-acetyl-2-amino-8-fluoroadenine F O-amino acid CH3 OH H O 2-N-acetylaminoadenine F O-amino acid CH3 OH H 0 2-N-acetylamino-8-fluoroadenine F 0-amino acid CH3 OH H O 2-N-acetylamino-8-fluorohypoxanthine F O-amino acid CH3 OH H O 2-N-acetylaminohypoxanthine F O-amino acid CH3 OH H O Thymine F O-acyl CH3 OH H 0 Uracil F 0-acyl CH3 OH H 0 Guanine F 0-acyl 3 OH H O Cytosine F O-acyl CH3 OH H O Adenine F O-acyl CH3 OH H O Hypoxanthine F O-acyl CH3 OH H O 5-Fluorouracil F O-ac 1 CH3 OH H O 8-Fluoroguanine F 0-acyl CH3 OH H O 5-Fluorocytosine F O-acyl CH3 OH H O 8-Fluoroadenine F O-acyl CH3 OH H O 2-Fluoroadenine F O-acyl CH3 OH H O 2, 8-Difluoroadenine F O-acyl CH3 OH H 0 2-Fluorohypoxanthine F 0-acyl CH3 OH H O 8-Fluorohypoxanthine F O-acyl CH3 OH H O 2, 8-Difluorohypoxanthine F O-acyl R6 R7 1 X Base R R CH3 OH H O 2-Aminoadenine F O-acyl CH3 OH H O 2-Amino-8-fluoroadenine F O-acyl CH3 OH H O 2-Amino-8-fluorohypoxanthine F O-acyl CH3 OH H O 2-Aminohypoxanthine F O-acyI CH3 OH H 0 2-N-acetylguanine F 0-acyl CH3 OH H O 4-N-acet lc osine F O-ac 1 CH3 OH H O 6-N-acetyladenine F O-acyl CH3 OH H O 2-N-acetyl-8-fluoroguanine F O-ac I Y CH3 OH H O 4-N-acetyl-5-fluorocytosine F O-acyl CH3 OH H O 6-N-acetyl-2-fluoroadenine F O-acyl CH3 OH H 0 6-N-acetyl-2, 8-difluoroadenine F 0-acyl CH3 OH H O 6-N-acetyl-2-aminoadenine F O-acyl CH3 OH H O 6-N-acetyl-2-amino-8-fluoroadenine F O-acyl CH3 OH H O 2-N-acetylaminoadenine F O-ac 1 CH3 OH H O 2-N-acetylamino-8-fluoroadenine F O-acyl CH3 OH H O 2-N-acetylamino-8-fluorohypoxanthine F O-acyl CH3 OH H O 2-N-acetylaminohypoxanthine F O-acyl CH3 OH H O Thymine Br O-amino acid CH3 OH H O Uracil Br O-amino acid CH3 OH H O Guanine Br O-amino acid CH3 OH H O Cytosine Br O-amino acid CH3 OH H O Adenine Br O-amino acid CH3 OH H O Hypoxanthine Br O-amino acid CH3 OH H O 5-Fluorouracil Br O-amino acid CH3 OH H O 8-Fluoroguanine Br O-amino acid CH3 OH H O 5-Fluorocytosine Br 0-amino acid CH3 OH H O 8-Fluoroadenine Br O-amino acid CH3 OH H O 2-Fluoroadenine Br O-amino acid CH3 OH H O 2, 8-Difluoroadenine Br O-amino acid CH3 OH H O 2-Fluorohypoxanthine Br O-amino acid CH3 OH H O 8-Fluorohypoxanthine Br O-amino acid CH3 OH H O 2, 8-Difluorohypoxanthine Br O-amino acid CH3 OH H O 2-Aminoadenine Br O-amino acid CH3 OH H O 2-Amino-8-fluoroadenine Br O-amino acid CH3 OH H 0 2-Amino-8-fluorohypoxanthine Br 0-amino acid CH3 OH H O 2-Aminohypoxanthine Br O-amino acid CH3 OH H O 2-N-acetylguanine Br O-amino acid CH3 OH H O 4-N-acet lc osine Br O-amino acid CH3 OH H O 6-N-acet ladenine Br O-amino acid CH3 OH H O 2-N-acetyl-8-fluoroguanine Br O-amino acid CH3 OH H O 4-N-acetyl-5-fluorocytosine Br O-amino acid CH3 OH H 0 6-N-acetyl-2-fluoroadenine Br 0-amino acid CH3 OH H O 6-N-acetyl-2, 8-difluoroadenine Br O-amino acid CH3 OH H 0 6-N-acetyl-2-aminoadenine Br 0-amino acid CH3 OH H O 6-N-acetyl-2-amino-8-fluoroadenine Br O-amino acid CH3 OH H O 2-N-acetylaminoadenine Br O-amino acid CH3 OH H O 2-N-acetylamino-8-fluoroadenine Br O-amino acid R6 R R X Base R R CH3 OH H O 2-N-acetylamino-8-fluorohypoxanthine Br O-amino acid CH3 OH H 0 2-N-acetylaminohypoxanthine Br 0-amino acid CH3 OH H O Thymine Br O-acyl CH3 OH H O Uracil Br O-acyl CH3 OH H 0 Guanine Br 0-acyl CH3 OH H 0 Cytosine Br 0-acyl CH3 OH H O Adenine Br O-acyl CH3 OH H 0 Hypoxanthine Br 0-acyl CH3 OH H O 5-Fluorouraci (Br O-ac 1 CH3 OH H O 8-Fluoroguanine Br O-acyl CH3 OH H O 5-Fluorocytosine Br O-acyl CH3 OH H O 8-Fluoroadenine Br O-ac 1 CH3 OH H O 2-Fluoroadenine Br O-acyl CH3 OH H O 2, 8-Difluoroadenine Br O-acyl CH3 OH H O 2-Fluorohypoxanthine Br O-acyl CH3 OH H O 8-Fluorohypoxanthine Br O-acyl CH3 OH H O 2, 8-Difluorohypoxanthine Br O-acyl CH3 OH H O 2-Aminoadenine Br O-acyl CH3 OH H O 2-Amino-8-fluoroadenine Br O-acyl CH3 OH H O 2-Amino-8-fluorohypoxanthine Br O-acyl CH3 OH H O 2-Aminohypoxanthine Br O-acyl CH3 OH H O 2-N-acetylguanine Br O-acyl CH3 OH H O 4-N-acetylcytosine Br O-acyl CH3 OH H O 6-N-acetyladenine Br O-acyl CH3 OH H O 2-N-acetyl-8-fluoroguanine Br O-acyl CH3 OH H O 4-N-acet 1-S-fluorocytosine Br O-ac 1 CH3 OH H O 6-N-acet 1-2-fluoroadenine Br O-acyl CH3 OH H 0 6-N-acetyl-2, 8-difluoroadenine Br 0-acyl CH3 OH H O 6-N-acetyl-2-aminoadenine Br O-acyl CH3 OH H O 6-N-acetyl-2-amino-8-fluoroadenine Br O-acyl CH3 OH H 0 2-N-acetylaminoadenine Br 0-acyl CH3 OH H 0 2-N-acetylamino-8-fluoroadenine Br 0-acyl CH3 OH H O 2-N-acetylamino-8-fluorohypoxanthine Br O-acyl CH3 OH H O 2-N-acetylaminohypoxanthine Br O-acyl CH3 OH H O Thymine Cl O-amino acid CH3 OH H O Uracil Cl O-amino acid CH3 OH H O Guanine Cl O-amino acid CH3 OH H O Cytosine Cl O-amino acid CH3 OH H O Adenine Cl O-amino acid CH3 OH H 0 Hypoxanthine Cl 0-amino acid CH3 OH H O 5-Fluorouracil Cl O-amino acid CH3 OH H 0 8-Fluoroguanine Cl 0-amino acid CH3 OH H O 5-Fluorocytosine Cl O-amino acid CH3 OH H O 8-Fluoroadenine Cl O-amino acid CH3 OH H 2-Fluoroadenine Cl 0-amino acid CH3 OH H O 2, 8-Difluoroadenine Cl O-amino acid CH3 OH H 0 2-Fluorohypoxanthine Cl 0-amino acid R6 R7 RS X Base R R CH3 OH H O 8-Fluorohypoxanthine Cl O-amino acid CH3 OH H O 2, 8-Difluorohypoxanthine Cl O-amino acid CH3 OH H O 2-Aminoadenine Cl O-amino acid CH3 OH H O 2-Amino-8-fluoroadenine Cl O-amino acid CH3 OH H O 2-Amino-8-fluorohypoxanthine C1 O-amino acid CH3 OH H O 2-Aminohypoxanthine Cl O-amino acid CH3 OH H O 2-N-acetylguanine Cl O-amino acid CH3 OH H O 4-N-acet Ic osine C1 O-amino acid CH3 OH H O 6-N-acetyladenine Cl O-amino acid CH3 OH H O 2-N-acetyl-8-fluoroguanine Cl O-amino acid CH3 OH H O 4-N-acetyl-5-fluoroc osine C1 O-amino acid CH3 OH H O 6-N-acetyl-2-fluoroadenine Cl O-amino acid CH3 OH H O 6-N-acetyl-2, 8-difluoroadenine Cl O-amino acid CH3 OH H 0 6-N-acetyl-2-aminoadenine Cl 0-amino acid CH3 OH H O 6-N-acetyl-2-amino-8-fluoroadenine Cl O-amino acid CH3 OH H O 2-N-acetylaminoadenine Cl O-amino acid CH3 OH H O 2-N-acetylamino-8-fluoroadenine Cl O-amino acid CH3 OH H O 2-N-acetylamino-8-fluorohypoxanthine Cl O-amino acid CH3 OH H O 2-N-acetylaminohypoxanthine Cl O-amino acid CH3 OH H O Thymine Cl O-acyl CH3 OH H O Uracil Cl O-acyl CH3 OH H O Guanine Cl O-acyl CH3 OH H 0 Cytosine Cl 0-acyl CH3 OH H 0 Adenine Cl 0-acyl CH3 OH H O Hypoxanthine Cl O-acyl CH3 OH H O 5-Fluorouracil Cl O-ac 1 CH3 OH H O 8-Fluoro uanine C1 O-acyl CH3 OH H O 5-Fluoroc osine Cl O-ac 1 CH3 OH H O 8-Fluoroadenine C1 O-ac 1 CH3 OH H O 2-Fluoroadenine Cl O-acyl CH3 OH H O 2, 8-Difluoroadenine C1 O-ac 1 CH3 OH H O 2-Fluorohypoxanthine Cl O-acyI CH3 OH H O 8-Fluorohy oxanthine CI O-ac 1 CH3 OH H O 2, 8-Difluorohy oxanthine CI O-acyl CH3 OH H O 2-Aminoadenine Cl O-acyl CH3 OH H O 2-Amino-8-fluoroadenine Cl O-acyl CH3 OH H O 2-Amino-8-fluorohypoxanthine Cl O-acyl CH3 OH H 0 2-Aminohypoxanthine Cl 0-acyl CH3 OH H O 2-N-acetylguanine Cl O-acyl CH3 OH H O 4-N-acetylcytosine Cl O-acyl CH3 OH H O 6-N-acetyladenine Cl O-acyl CH3 OH H O 2-N-acetyl-8-fluoroguanine Cl O-acyl CH3 OH H O 4-N-acetyl-5-fluorocytosine Cl O-acyl CH3 OH H O 6-N-acetyl-2-fluoroadenine CI O-ac 1 CH3 OH H O 6-N-acetyl-2, 8-difluoroadenine Cl O-acyl CH3 OH H O 6-N-acetyl-2-aminoadenine Cl O-acyl CH3 OH H O 6-N-acetyl-2-amino-8-fluoroadenine Cl O-acyl R7 T X Base Rlo R9 CH3 OH H O 2-N-acetylaminoadenine Cl O-acyl CH3 OH H O 2-N-acetylamino-8-fluoroadenine Cl O-acyl CH3 OH H 0 2-N-acetylamino-8-fluorohypoxanthine Cl 0-acyl CH3 OH H 0 2-N-acetylaminohypoxanthine Cl 0-acyl CH3 OH H O Thymine H O-amino acid CH3 OH H O Uracil H O-amino acid CH3 OH H O Guanine H O-amino acid CH3 OH H O Cytosine H O-amino acid CH3 OH H O Adenine H O-amino acid CH3 OH H O Hypoxanthine H O-amino acid CH3 OH H O 5-Fluorouracil H O-amino acid CH3 OH H O 8-Fluoroguanine H 0-amino acid CH3 OH H O 5-Fluorocytosine H O-amino acid CH3 OH H O 8-Fluoroadenine H O-amino acid CH3 OH H O 2-Fluoroadenine H O-amino acid CH3 OH H O 2, 8-Difluoroadenine H O-amino acid CH3 OH H O 2-Fluorohypoxanthine H O-amino acid CH3 OH H O 8-Fluorohypoxanthine H O-amino acid CH3 OH H O 2, 8-Difluorohypoxanthine H 0-amino acid CH3 OH H O 2-Aminoadenine H O-amino acid CH3 OH H 0 2-Amino-8-fluoroadenine H 0-amino acid CH3 OH H O 2-Amino-8-fluorohypoxanthine H O-amino acid CH3 OH H 0 2-Aminohypoxanthine H 0-amino acid CH3 OH H O 2-N-acetylguanine H O-amino acid CH3 OH H O 4-N-acet lcytosine H O-amino acid CH3 OH H O 6-N-acetyladenine H O-amino acid CH3 OH H O 2-N-acetyl-8-fluoroguanine H O-amino acid CH3 OH H O 4-N-acetyl-5-fluorocytosine H O-amino acid CH3 OH H O 6-N-acetyl-2-fluoroadenine H O-amino acid CH3 OH H O 6-N-acetyl-2, 8-difluoroadenine H O-amino acid CH3 OH H O 6-N-acetyl-2-aminoadenine H O-amino acid CH3 OH H O 6-N-acetyl-2-amino-8-fluoroadenine H O-amino acid CH3 OH H O 2-N-acetylaminoadenine H O-amino acid CH3 OH H O 2-N-acetylamino-8-fluoroadenine H O-amino acid CH3 OH H O 2-N-acetylamino-8-fluorohypoxanthine H O-amino acid CH3 OH H 0 2-N-acetylaminohypoxanthine H 0-amino acid CH3 OH H O Thymine H O-acyl CH3 OH H O Uracil H O-acyl CH3 OH H O Guanine H O-acyl CH3 OH H O Cytosine H O-acyl CH3 OH H 0 Adenine H 0-acyl CH3 OH H O Hypoxanthine H O-acyl CH3 OH H O 5-Fluorouracil H O-acyl CH3 OH H O 8-Fluoroguanine H O-acyl CH3 OH H O 5-Fluoroc osine H O-ac 1 3 OH H O 8-Fluoroadenine H O-ac 1 CH3 OH H O 2-Fluoroadenine H O-acyl R6 R R X Base R R9 CH3 OH H O 2, 8-Difluoroadenine H O-acyl CH3 OH H O 2-Fluorohypoxanthine H 0-acyl CH3 OH H O 8-Fluorohypoxanthine H O-acyl CH3 OH H O 2, 8-Difluorohypoxanthine H O-acyl CH3 OH H 0 2-Aminoadenine H 0-acyl CH3 OH H 0 2-Amino-8-fluoroadenine H 0-acyl CH3 OH H O 2-Amino-8-fluorohypoxanthine H O-acyl CH3 OH H 0 2-Aminohypoxanthine H 0-acyl CH3 OH H O 2-N-acet 1 uanine H O-ac 1 CH3 OH H O 4-N-acetylcytosine H O-acyl CH3 OH H 0 6-N-acetyladenine H 0-acyl CH3 OH H O 2-N-acetyl-8-fluoroguanine H O-acyl CH3 OH H O 4-N-acet 1-5-fluorocytosine H O-acyl CH3 OH H O 6-N-acetyl-2-fluoroadenine H O-acyl CH3 OH H 0 6-N-acetyl-2, 8-difluoroadenine H 0-acyl CH3 OH H 0 6-N-acetyl-2-aminoadenine H 0-acyl CH3 OH H 0 6-N-acetyl-2-amino-8-fluoroadenine H 0-acyl CH3 OH H 0 2-N-acetylaminoadenine H 0-acyl CH3 OH H O 2-N-acetylamino-8-fluoroadenine H O-acyl CH3 OH H O 2-N-acetylamino-8-fluorohypoxanthine H O-acyl CH3 OH H O 2-N-acetylaminohy oxanthine H O-acyl CH3 H F O Thymine F O-amino acid CH3 H F O Uracil F O-amino acid CH3 H F O Guanine F O-amino acid CH3 H F O Cytosine F O-amino acid CH3 H F O Adenine F O-amino acid CH3 H F O Hypoxanthine F O-amino acid CH3 H F O 5-Fluorouracil F O-amino acid CH3 H F O 8-Fluoroguanine F O-amino acid CH3 H F O 5-Fluorocytosine F O-amino acid CH3 H F O 8-Fluoroadenine F O-amino acid CH3 H F O 2-Fluoroadenine F O-amino acid CH3 H F O 2, 8-Difluoroadenine F O-amino acid CH3 H F O 2-Fluorohypoxanthine F O-amino acid CH3 H F O 8-Fluorohy oxanthine F O-amino acid CH3 H F O 2, 8-Difluorohypoxanthine F O-amino acid CH3 H F O 2-Aminoadenine F O-amino acid CH3 F O 2-Amino-8-fluoroadenine F O-amino acid CH3 H F O 2-Amino-8-fluorohypoxanthine F O-amino acid CH3 H F O 2-Aminohypoxanthine F O-amino acid CH3 H F O 2-N-acetylguanine F O-amino acid CH3 H F O 4-N-acetylcytosine F O-amino acid CH3 H F O 6-N-acetyladenine F O-amino acid CH3 H F O 2-N-acetyl-8-fluoroguanine F O-amino acid CH3 H F O 4-N-acetyl-5-fluoroc osine F O-amino acid CH3 H F O 6-N-acetyl-2-fluoroadenine F O-amino acid CH3 F O 6-N-acetyl-2, 8-difluoroadenine F O-amino acid R R R X Base R R CH3 H F O 6-N-acetyl-2-aminoadenine F O-amino acid CH3 H F O 6-N-acetyl-2-amino-8-fluoroadenine F O-amino acid CH3 H F O 2-N-acetylaminoadenine F O-amino acid CH3 H F 0 2-N-acetylamino-8-fluoroadenine F 0-amino acid CH3 H F O 2-N-acetylamino-8-fluorohypoxanthine F O-amino acid CH3 H F O 2-N-acetylaminohypoxanthine F 0-amino acid CH3 H F O Thymine F O-acyl CH3 H F O Uracil F O-acyl CH3 H F 0 Guanine F 0-acyl CH3 H F O Cytosine F O-acyl CH3 H F O Adenine F O-acyl CH3 H F O Hypoxanthine F O-acyl CH3 H F O 5-Fluorouracil F O-ac 1 # CH3 H F O 8-Fluoroguanine F O-acyl CH3 H F O 5-Fluorocytosine F O-acyl CH3 H F O 8-Fluoroadenine F O-acyl CH3 H F O 2-Fluoroadenine F O-acyl CH3 H F O 2, 8-Difluoroadenine F O-acyl CH3 H F O 2-Fluorohypoxanthine F O-acyl CH3 H F O 8-Fluorohypoxanthine F O-acyl CH3 H F O 2, 8-Difluorohypoxanthine F O-acyl CH3 H F 0 2-Aminoadenine F 0-acyl CH3 H F O 2-Amino-8-fluoroadenine F O-acyl CH3 H F O 2-Amino-8-fluorohy oxanthine F O-acyl CH3 H F O 2-Aminohy oxanthine F O-ac 1 CH3 H F O 2-N-acetylguanine F O-acyl CH3 H F O 4-N-acetylcytosine F O-acyl CH3 H F O 6-N-acetyladenine F O-acyl CH3 H F O 2-N-acetyl-8-fluoroguanine F O-acyl CH3 H F O 4-N-acetyl-5-fluorocytosine F O-acyl CH3 H F O 6-N-acetyl-2-fluoroadenine F O-acyl CH3 H F O 6-N-acetyl-2, 8-difluoroadenine F O-acyl CH3 H F 0 6-N-acetyl-2-aminoadenine F 0-acyl CH3 H F O 6-N-acetyl-2-amino-8-fluoroadenine F O-acyl CH3 H F 0 2-N-acetylaminoadenine F 0-acyl CH3 H F O 2-N-acetylamino-8-fluoroadenine F O-acyl CH3 H F 0 2-N-acetylamino-8-fluorohypoxanthine F 0-acyl CH3 H F O 2-N-acet laminohy oxanthine F O-acyl CH3 H F O Thymine Br O-amino acid CH3 H F O Uracil Br O-amino acid CH3 H F O Guanine Br O-amino acid CH3 H F 0 Cytosine Br 0-amino acid CH3 H F O Adenine Br O-amino acid CH3 H F 0 Hypoxanthine Br 0-amino acid CH3 H F O 5-Fluorouracil Br O-amino acid CH3 H F O 8-Fluoro uanine Br O-amino acid CH3 H F O 5-Fluorocytosine Br O-amino acid R7 T X Base R R CH3 H F O 8-Fluoroadenine Br O-amino acid CH3 H F O 2-Fluoroadenine Br O-amino acid CH3 H F O 2, 8-Difluoroadenine Br O-amino acid CH3 H F O 2-Fluorohy oxanthine Br O-amino acid CH3 H F O 8-Fluoroh oxanthine Br O-amino acid CH3 H F O 2, 8-Difluorohypoxanthine Br 0-amino acid CH3 H F O 2-Aminoadenine Br O-amino acid CH3 H F O 2-Amino-8-fluoroadenine Br O-amino acid CH3 H F 0 2-Amino-8-fluorohypoxanthine Br 0-amino acid CH3 H F 0 2-Aminohypoxanthine Br 0-amino acid CH3 H F O 2-N-acetylguanine Br O-amino acid CH3 H F O 4-N-acet lc osine Br O-amino acid CH3 H F O 6-N-acetyladenine Br O-amino acid CH3 H F O 2-N-acetyl-8-fluoroguanine Br O-amino acid CH3 H F O 4-N-acetyl-5-fluorocytosine Br O-amino acid CH3 H F O 6-N-acetyl-2-fluoroadenine Br O-amino acid CH3 H F O 6-N-acetyl-2, 8-difluoroadenine Br O-amino acid CH3 H F 0 6-N-acetyl-2-aminoadenine Br 0-amino acid CH3 H F O 6-N-acetyl-2-amino-8-fluoroadenine Br O-amino acid CH3 H F 0 2-N-acetylaminoadenine Br 0-amino acid CH3 H F O 2-N-acetylamino-8-fluoroadenine Br O-amino acid CH3 H F O 2-N-acetylamino-8-fluorohypoxanthine Br O-amino acid CH3 H F O 2-N-acetylaminohypoxanthine Br O-amino acid CH3 H F O Thymine Br O-acyl CH3 H F O Uracil Br O-acyl CH3 H F O Guanine Br O-acyl CH3 H F O C osine Br O-acyl CH3 H F O Adenine Br O-acyl CH3 H F O Hypoxanthine Br O-acyl CH3 H F O 5-Fluorouracil Br 0-acyl CH3 H F O 8-Fluoroguanine Br O-aeyl CH3 H F O 5-Fluorocytosine Br O-acyl CH3 H F O 8-Fluoroadenine Br O-ac 1 CH3 H F O 2-Fluoroadenine Br O-ac 1 CH3 H F O 2, 8-Difluoroadenine Br O-acyl CH3 H F O 2-Fluorohypoxanthine Br O-acyl CH3 H F O 8-Fluoroh oxanthine Br O-acyl CH3 H F O 2, 8-Difluorohy oxanthine Br O-ac 1 CH3 H F 0 2-Aminoadenine Br 0-acyl CH3 H F 0 2-Amino-8-fluoroadenine Br 0-acyl CH3 H F O 2-Amino-8-fluorohypoxanthine Br O-acyl CH3 H F O 2-Aminohypoxanthine Br O-acyl CH3 H F O 2-N-acetylguanine Br O-acyl CH3 H F O 4-N-acetylcytosine Br O-ac 1 CH3 H F 0 6-N-acetyladenine r 0-a CH3 H F _O 2-N-acetyl-8-fluoroguanine Br O-acyl CH3 H F O 4-N-acetyl-5-fluorocytosine Br O-acyl R R R X Base R R CH3 H F O 6-N-acetyl-2-fluoroadenine Br O-acyl CH3 H F 0 6-N-acetyl-2, 8-difluoroadenine Br 0-acyl CH3 H F O 6-N-acetyl-2-aminoadenine Br O-acyl CH3 H F O 6-N-acetyl-2-amino-8-fluoroadenine Br 0-acyl CH3 H F O 2-N-acetylaminoadenine Br O-acyl CH3 H F O 2-N-acetylamino-8-fluoroadenine Br O-acyl CH3 H F O 2-N-acetylamino-8-fluorohypoxanthine Br 0-acyl CH3 H F 0 2-N-acetylaminohypoxanthine Br 0-acyl CH3 H F O Thymine Cl O-amino acid CH3 H F 0 Uracil Cl 0-amino acid CH3 H F O Guanine Cl O-amino acid CH3 H F O Cytosine Cl O-amino acid CH3 H F 0 Adenine Cl 0-amino acid CH3 H F O Hypoxanthine Cl O-amino acid CH3 H F O 5-Fluorouracil Cl 0-amino acid CH3 H F O 8-Fluoroguanine Cl O-amino acid CH3 H F O 5-Fluorocytosine Cl O-amino acid CH3 H F O 8-Fluoroadenine Cl O-amino acid CH3 H F O 2-Fluoroadenine Cl O-amino acid CH3 H F O 2, 8-Difluoroadenine Cl O-amino acid CH3 H F O 2-Fluorohypoxanthine Cl O-amino acid CH3 H F O 8-Fluorohypoxanthine Cl O-amino acid CH3 H F O 2, 8-Difluorohypoxanthine Cl O-amino acid CH3 H F O 2-Aminoadenine Cl O-amino acid CH3 H F O 2-Amino-8-fluoroadenine Cl O-amino acid CH3 H F O 2-Amino-8-fluorohy oxanthine Cl O-amino acid CH3 H F O 2-Aminohypoxanthine Cl O-amino acid CH3 H F O 2-N-acetylguanine Ci O-amino acid CH3 H F O 4-N-acetylcytosine Cl O-amino acid CH3 H F O 6-N-acetyladenine Cl O-amino acid CH3 H F O 2-N-acetyl-8-fluoroguanine Cl O-amino acid CH3 H F O 4-N-acetyl-5-fluoroc osine C1 O-amino acid CH3 H F O 6-N-acetyl-2-fluoroadenine Cl O-amino acid CH3 H F O 6-N-acetyl-2, 8-difluoroadenine Cl O-amino acid CH3 H F O 6-N-acetyl-2-aminoadenine Cl O-amino acid CH3 H F O 6-N-acetyl-2-amino-8-fluoroadenine Cl O-amino acid CH3 H F O 2-N-acet laminoadenine C1 O-amino acid CH3 H F 0 2-N-acetylamino-8-fluoroadenine Cl 0-amino acid CH3 H F O 2-N-acetylamino-8-fluorohypoxanthine Cl O-amino acid CH3 H F O 2-N-acetylaminohypoxanthine C1 O-amino acid CH3 H F 0 Thymine Cl 0-acyl CH3 H F O Uracil Cl O-acyl CH3 H F O Guanine Cl O-acyl CH3 H F O Cytosine Cl O-acyl CH3 H F O Adenine Cl O-acyl CH3 H F O Hypoxanthine Cl O-ac 1 CH3 H F O 5-Fluorouraci I Cl O-acyl R T X Base w R9 CH3 H F O 8-Fluoroguanine Cl O-acyl CH3 H F O 5-Fluoroc osine Cl O-acyl CH3 H F O 8-Fluoroadenine CI O-acyl CH3 H F O 2-Fluoroadenine Cl O-ac 1 CH3 H F O 2, 8-Difluoroadenine Cl O-acyl CH3 H F O 2-Fluoroh oxanthine Cl O-acyl CH3 H F O 8-Fluoroh oxanthine Cl O-acyl CH3 H F O 2, 8-Difluorohy oxanthine Cl O-ac 1 CH3 H F O 2-Aminoadenine Cl O-ac 1 CH3 H F O 2-Amino-8-fluoroadenine Cl O-acyl CH3 H F O 2-Amino-8-fluorohypoxanthine Cl O-acyl CH3 H F O 2-Aminohypoxanthine Cl O-acyl CH3 H F O 2-N-acetylguanine CI O-acyl CH3 H F O 4-N-acetylc osine Cl O-ac 1 CH3 H F O 6-N-acetyladenine Cl O-acyl CH3 H F O 2-N-acetyl-8-fluoroguanine Cl O-acyl CH3 H F O 4-N-acetyl-5-fluorocytosine Cl O-acyl CH3 H F O 6-N-acetyl-2-fluoroadenine Cl O-acyl CH3 H F 0 6-N-acetyl-2, 8-difluoroadenine Cl 0-acyl CH3 H F O 6-N-acetyl-2-aminoadenine Cl O-acyl CH3 H F O 6-N-acetyl-2-amino-8-fluoroadenine Cl O-acyl CH3 H F O 2-N-acetylaminoadenine Cl O-acyl CH3 H F 0 2-N-acetylamino-8-fluoroadenine Cl 0-acyl CH3 H F O 2-N-acetylamino-8-fluorohypoxanthine Cl O-acyl CH3 H F O 2-N-acetylaminohypoxanthine Cl O-acyl CH3 H F O Thymine H O-amino acid CH3 H F O Uracil H O-amino acid CH3 H F 0 Guanine H 0-amino acid CH3 H F O Cytosine H O-amino acid CH3 H F. O Adenine H O-amino acid CH3 H F O Hypoxanthine H O-amino acid CH3 H F O 5-Fluorouraeil H O-amino acid CH3 H F O 8-Fluoroguanine H O-amino aeid CH3 H F O 5-Fluorocytosine H O-amino acid CH3 H F O 8-Fluoroadenine H O-amino aeid CH3 H F O 2-Fluoroadenine H O-amino acid CH3 H F O 2, 8-Difluoroadenine H O-amino acid CH3 H F O 2-Fluorohypoxanthine H O-amino acid CH3 H F O 8-Fluorohy oxanthine H O-amino acid CH3 H F O 2, 8-Difluorohypoxanthine H O-amino acid CH3 H F O 2-Aminoadenine H O-amino acid CH3 H F O 2-Amino-8-fluoroadenine H O-amino acid CH3 H F O 2-Amino-8-fluoroh oxanthine H O-amino acid CH3 H F O 2-Aminohypoxanthine H O-amino acid CH3 H F 0 2-N-acetylguanine H 0-amino acid CH3 H F 0 4-N-acetylcytosine H 0-amino acid CH3 H F O 6-N-acetyladenine H O-amino acid R7 R R X Base R ° R CH3 H F 0 2-N-acetyl-8-fluoroguanine 0-amino acid CH3 H F 0 4-N-acetyl-5-fluorocytosine H 0-amino acid CH3 H F O 6-N-acetyl-2-fluoroadenine H O-amino acid CH3 H F O 6-N-acetyl-2, 8-difluoroadenine H O-amino acid CH3 H F 0 6-N-acetyl-2-aminoadenine H 0-amino acid CH3 H F 0 6-N-acetyl-2-amino-8-fluoroadenine H 0-amino acid CH3 H F O 2-N-acetylaminoadenine H O-amino acid CH3 H F O 2-N-acetylamino-8-fluoroadenine H O-amino acid CH3 H F O 2-N-acetylamino-8-fluorohypoxanthine H O-amino acid CH3 H F 0 2-N-acetylaminohypoxanthine H 0-amino acid CH3 H F 0 Thymine H 0-acyl CH3 H F O Uracil H O-acyl CH3 H F O Guanine H O-acyl CH3 H F 0 Cytosine H 0-acyl CH3 H F O Adenine H O-acyl CH3 H F 0 Hypoxanthine H 0-acyl CH3 H F O S-Fluorouracil H O-acyl CH3 H F O 8-Fluoroguanine H O-acyl CH3 H F O 5-Fluorocytosine H O-ac 1 CH3 H F 0 8-Fluoroadenine H O-acyl CH3 H F O 2-Fluoroadenine H O-acyl CH3 H F O 2, 8-Difluoroadenine H O-acyl CH3 H F O 2-Fluorohypoxanthine H 0-acyl CH3 H F O 8-Fluorohy oxanthine H O-ac 1 CH3 H F O 2, 8-Difluorohy oxanthine H O-ac 1 CH3 H F 0 2-Aminoadenine H 0-acyl CH3 H F O 2-Amino-8-fluoroadenine H O-acyl CH3 H F O 2-Amino-8-fluorohypoxanthine H O-acyl CH3 H F 0 2-Aminohypoxanthine H 0-acyl CH3 H F O 2-N-acetylguanine H O-acyl CH3 H F O 4-N-acetylcytosine H O-acyl CH3 H F O 6-N-acetyladenine H O-ac 1 CH3 H F O 2-N-acetyl-8-fluoroguanine H O-acyl CH3 H F O 4-N-acetyl-S-fluorocytosine H O-acyl CH3 H F 0 6-N-acetyl-2-fluoroadenine H 0-acyl CH3 H F O 6-N-acetyl-2, 8-difluoroadenine H O-acyl CH3 H F O 6-N-acet 1-2-aminoadenine H O-acyl CH3 H F O 6-N-acetyl-2-amino-8-fluoroadenine H O-acyl CH3 H F 0 2-N-acetylaminoadenine H 0-acyl CH3 H F O 2-N-acetylamino-8-fluoroadenine H O-acyl CH3 H F O 2-N-acetylamino-8-fluorohypoxanthine H O-acyl CH3 H F O 2-N-acetylaminohypoxanthine H O-acyl CH3 H Br O Thymine F O-amino acid CH3 H Br O Uracil F O-amino acid CH3 H Br O = F O-amino acid CH3 H Br O Cytosine F O-amino acid CH3 H Br O Adenine F O-amino acid R7 R8 X Base w R9 CH3 H Br O Hypoxanthine F O-amino acid CH3 H Br O 5-Fluorouracil F O-amino acid CH3 H Br O 8-Fluoroguanine F O-amino acid CH3 H Br O 5-Fluorocytosine F O-amino acid CH3 H Br O 8-Fluoroadenine F O-amino acid CH3 H Br O 2-Fluoroadenine F O-amino acid CH3 H Br O 2, 8-Difluoroadenine F O-amino acid CH3 H Br O 2-Fluorohy oxanthine F O-amino acid CH3 H Br O 8-Fluorohypoxanthine F O-amino acid CH3 H Br O 2, 8-Difluorohypoxanthine F O-amino acid CH3 H Br O 2-Aminoadenine F O-amino acid CH3 H Br O 2-Amino-8-fluoroadenine F O-amino acid CH3 H Br O 2-Amino-8-fluorohypoxanthine F O-amino acid CH3 H Br 0 2-Aminohypoxanthine F 0-amino acid CH3 H Br O 2-N-acetylguanine F O-amino acid CH3 H Br 0 4-N-acetylcytosine F 0-amino acid CH3 H Br O 6-N-acetyladenine F O-amino acid CH3 H Br O 2-N-acetyl-8-fluoroguanine F O-amino acid CH3 H Br O 4-N-acetyl-5-fluorocytosine F O-amino acid CH3 H Br O 6-N-acetyl-2-fluoroadenine F O-amino acid CH3 H Br O 6-N-acetyl-2, 8-difluoroadenine F O-amino acid CH3 H Br O 6-N-acetyl-2-aminoadenine F O-amino acid CH3 H Br O 6-N-acetyl-2-amino-8-fluoroadenine F O-amino acid CH3 H Br O 2-N-acetylaminoadenine F O-amino acid CH3 H Br O 2-N-acetylamino-8-fluoroadenine F O-amino acid CH3 H Br O 2-N-acetylamino-8-fluorohypoxanthine F O-amino acid CH3 H Br 0 2-N-acetylaminohypoxanthine F 0-amino acid CH3 H Br 0 Thymine F 0-acyl CH3 H Br O Uracil F O-acyl CH3 H Br O Guanine F O-acyl CH3 H Br O Cytosine F O-acyl CH3 H Br O Adenine F O-acyl CH3 H Br 0 Hypoxanthine F 0-acyl CH3 H Br O 5-Fluorouracil F O-acyl CH3 H Br O 8-Fluoroguanine F O-acyl CH3 H Br O 5-Fluorocytosine F O-acyl CH3 H Br O 8-Fluoroadenine F O-acyl CH3 H Br O 2-Fluoroadenine F O-acyl CH3 H Br O 2, 8-Difluoroadenine F O-ac 1 CH3 H Br O 2-Fluorohypoxanthine F O-acyl CH3 H Br O 8-Fluorohypoxanthine F O-acyl CH3 H Br O 2, 8-Difluorohypoxanthine F O-acyl CH3 H Br O 2-Aminoadenine F O-acyl CH3 H Br 0 2-Amino-8-fluoroadenine F 0-acyl CH3 H Br 0 2-Amino-8-fluorohypoxanthine F 0-acyl CH3 H Br 0 2-Aminohypoxanthine F 0-acyl CH3 H Br O 2-N-acetyl guanine F O-acyl R R'R X Base R R CH3 H Br O 4-N-acetylcytosine F O-acyl CH3 H Br O 6-N-acetyladenine F O-acyl CH3 H Br O 2-N-acetyl-8-fluoroguanine F O-acyl CH3 H Br O 4-N-acetyl-5-fluorocytosine F O-acyl CH3 H Br 0 6-N-acetyl-2-fluoroadenine F 0-acyl CH3 H Br O 6-N-acetyl-2, 8-difluoroadenine F O-acyl CH3 H Br O 6-N-acetyl-2-aminoadenine F O-acyl CH3 H Br O 6-N-acetyl-2-amino-8-fluoroadenine F O-acyl CH3 H Br 0 2-N-acetylaminoadenine F 0-acyl CH3 H Br 0 2-N-acetylamino-8-fluoroadenine F 0-acyl CH3 H Br O 2-N-acetylamino-8-fluorohypoxanthine F O-acyl CH3 H Br O 2-N-acetylaminohypoxanthine F O-acyl CH3 H Br 0 Thymine Br 0-amino acid CH3 H Br O Uracil Br O-amino acid CH3 H Br O Guanine Br O-amino acid CH3 H Br 0 Cytosine Br 0-amino acid CH3 H Br O Adenine Br O-amino acid CH3 H Br 0 Hypoxanthine Br 0-amino acid CH3 H Br O 5-Fluorouracil Br O-amino acid CH3 H Br O 8-Fluoroguanine Br O-amino acid CH3 H Br O 5-Fluorocytosine Br O-amino acid CH3 H Br O 8-Fluoroadenine Br O-amino acid CH3 H Br O 2-Fluoroadenine Br O-amino acid CH3 H Br O 2, 8-Difluoroadenine Br O-amino acid CH3 H Br 0 2-Fluorohypoxanthine Br 0-amino acid CH3 H Br O 8-Fluorohypoxanthine Br O-amino acid CH3 H Br O 2, 8-Difluorohypoxanthine Br O-amino acid CH3 H Br O 2-Aminoadenine Br O-amino acid CH3 H Br O 2-Amino-8-fluoroadenine Br O-amino acid CH3 H Br O 2-Amino-8-fluorohypoxanthine Br O-amino acid CH3 H Br 0 2-Aminohypoxanthine Br 0-amino acid CH3 H Br O 2-N-acetylguanine Br O-amino acid CH3 H Br O 4-N-acetylcytosine Br O-amino acid CH3 H Br O 6-N-acetyladenine Br O-amino acid CH3 H Br O 2-N-acetyl-8-fluoroguanine Br O-amino acid CH3 H Br O 4-N-acetyl-5-fluorocytosine Br O-amino acid CH3 H Br O 6-N-acetyl-2-fluoroadenine Bf O-amino acid CH3 H Br O 6-N-acetyl-2, 8-difluoroadenine Br O-amino acid CH3 H Br O 6-N-acetyl-2-aminoadenine Br O-amino acid CH3 H Br O 6-N-acetyl-2-amino-8-fluoroadenine Br O-amino acid CH3 H Br O 2-N-acetylaminoadenine Br O-amino acid CH3 H Br O 2-N-acetylamino-8-fluoroadenine Br O-amino acid CH3 H Br O 2-N-acetylamino-8-fluorohypoxanthine Br O-amino acid CH3 H Br 0 2-N-acetylaminohypoxanthine Br 0-amino acid CH3 H Br O Thymine Br O-acyl CH3 H Br O Uracil Br O-acyl CH3 H Br O Guanine Br O-acyl R6 R7 T X Base Rl° R9 CH3 H Br O Cytosine Br O-acyl CH3 H Br O Adenine Br O-acyl CH3 H Br 0 Hypoxanthine Br 0-acyl CH3 H Br O 5-Fluorouracil Br O-acyl CH3 H Br O 8-Fluoroguanine Br O-acyl CH3 H Br O 5-Fluorocytosine Br O-ac 1 CH3 H Br O 8-Fluoroadenine Br O-acyl CH3 H Br O 2-Fluoroadenine Br O-acyl CH3 H Br O 2, 8-Difluoroadenine Br O-acyl CH3 H Br O 2-Fluorohy oxanthine Br O-acyl CH3 H Br O 8-Fluorohy oxanthine Br O-acyl CH3 H Br O 2, 8-Difluorohypoxanthine Br O-acyl CH3 H Br 0 2-Aminoadenine Br 0-acyl CH3 H Br O 2-Amino-8-fluoroadenine Br O-acyl CH3 H Br O 2-Amino-8-fluorohypoxanthine Br O-acyl CH3 H Br O 2-Aminohy oxanthine Br O-acyl CH3 H Br O 2-N-acetylguanine Br O-acyl CH3 H Br O 4-N-acetylcytosine Br O-acyl CH3 H Br O 6-N-acetyladenine Br O-acyl CH3 H Br O 2-N-acet 1-8-fluoroguanine Br O-ac 1 CH3 H Br O 4-N-acetyl-5-fluorocytosine Br O-acyl CH3 H Br O 6-N-acetyl-2-fluoroadenine Br O-acyl CH3 H Br O 6-N-acetyl-2, 8-difluoroadenine Br O-acyl CH3 H Br O 6-N-acetyl-2-aminoadenine Br O-acyl CH3 H Br O 6-N-acetyl-2-amino-8-fluoroadenine Br 0-acy) CH3 H Br O 2-N-acetylaminoadenine Br O-acyl CH3 H Br O 2-N-acetylamino-8-fluoroadenine Br O-acyl CH3 H Br O 2-N-acetylamino-8-fluorohypoxanthine Br O-acyl CH3 H Br O 2-N-acetylaminohypoxanthine Br O-acyl CH3 H Br O Thymine Cl O-amino acid CH3 H Br O Uracil Cl O-amino acid CH3 H Br O Guanine Cl O-amino acid CH3 H Br O Cytosine Cl O-amino acid CH3 H Br O Adenine Cl O-amino acid CH3 H Br O Hypoxanthine Cl O-amino acid CH3 H Br O 5-Fluorouracil Cl O-amino acid CH3 H Br O 8-Fluoroguanine Cl O-amino acid CH3 H Br O S-Fluorocytosine Cl O-amino acid CH3 H Br O 8-Fluoroadenine Cl O-amino acid CH3 H Br O 2-Fluoroadenine Cl O-amino acid CH3 H Br O 2, 8-Difluoroadenine Cl O-amino acid CH3 H Br O 2-Fluorohypoxanthine Cl O-amino acid CH3 H Br O 8-Fluorohypoxanthine Cl O-amino acid CH3 H Br O 2, 8-Difluorohypoxanthine Cl O-amino acid CH3 H Br O 2-Aminoadenine Cl O-amino acid CH3 H Br O 2-Amino-8-fluoroadenine Cl O-amino acid CH3 H Br O 2-Amino-8-fluorohypoxanthine Cl O-amino acid R R R X Base R R CH3 H Br O 2-Aminohypoxanthine Cl O-amino acid CH3 H Br 0 2-N-acetylguanine Cl 0-amino acid CH3 H Br O 4-N-acetylcytosine Cl O-amino acid CH3 H Br O 6-N-acetyladenine Cl O-amino acid CH3 H Br O 2-N-acety1-8-fluoroguanine Cl O-amino acid CH3 H Br O 4-N-acetyl-5-fluorocytosine Cl O-amino acid CH3 H Br O 6-N-acetyl-2-fluoroadenine Cl O-amino acid CH3 H Br O 6-N-acetyl-2, 8-difluoroadenine Cl O-amino acid CH3 H Br O 6-N-acetyl-2-aminoadenine Cl O-amino acid CE3 H Br O 6-N-acetyl-2-amino-8-fluoroadenine Cl O-amino acid CH3 H Br O 2-N-acetylaminoadenine Cl O-amino acid CH3 H Br O 2-N-acetylamino-8-fluoroadenine Cl O-amino acid CH3 H Br O 2-N-acetylam ino-8-fluorohypoxanthine Cl O-amino acid CH3 H Br O 2-N-acetylaminohypoxanthine Cl O-amino acid CH3 H Br 0 Thymine Cl 0-acyl CH3 H Br O Uracil Cl O-acyl CH3 H Br O Guanine Cl O-acyl CH3 H Br O Cytosine Cl O-acyl CH3 H Br O Adenine Cl O-acyl CH3 H Br O Hypoxanthine Cl O-acyl CH3 H Br O 5-Fluorouracil Cl O-acyl CH3 H Br O 8-Fluoroguanine Cl O-acyl CH3 H Br O 5-Fluorocytosine Cl O-acyl CH3 H Br 0 8-Fluoroadenine Cl 0-acyl CH3 H Br O 2-Fluoroadenine Cl O-aceI CH3 H Br O 2, 8-Difluoroadenine Cl O-acyl CH3 H Br O 2-Fluorohypoxanthine Cl O-acyl CH3 H Br O 8-Fluorohypoxanthine Cl O-acyl CH3 H _ Br O 2, 8-Difluorohypoxanthine Cl O-acyl CH3 H Br O 2-Aminoadenine Cl O-acyl CH3 H Br O 2-Amino-8-fluoroadenine Cl O-ac 1 CH3 H Br O 2-Amino-8-fluorohy oxanthine Cl O-ac 1 CH3 H Br O 2-Aminohypoxanthine Cl O-acyl CH3 H Br O 2-N-acetylguanine Cl O-acyl CH3 H Br O 4-N-acetylcytosine Cl O-acyl CH3 H Br O 6-N-acetyladenine Cl O-acyl CH3 H Br O 2-N-acetyl-8-fluoroguanine Cl O-acyl CH3 H Br O 4-N-acetyl-5-fluorocytosine Cl O-acyl CH3 H Br O 6-N-acetyI-2-fluoroadenine Cl O-acyl CH3 H Br O 6-N-acetyl-2, 8-difluoroadenine Cl O-acyl CH3 H Br O 6-N-acetyl-2-aminoadenine Cl O-acyl CH3 H Br O 6-N-acetyl-2-amino-8-fluoroadenine Cl O-acyl CH3 H Br O 2-N-acetylaminoadenine Cl O-acyl CH3 H Br O 2-N-acetylamino-8-fluoroadenine Cl O-acyl CH3 H Br O 2-N-acetylamino-8-fluorohypoxanthine Cl O-acyl CH3 H Br O 2-N-acetyla_minohypoxanthine Cl O-acyl CH3 H Br O Thymine H O-amino acid R6 I R7 F X Base R R CH3 H Br O Uracil H O-amino acid CH3 H Br O Guanine H O-amino acid CH3 H Br O Cytosine H O-amino acid CH3 H Br O Adenine H O-amino acid CH3 H Br 0 Hypoxanthine H 0-amino acid CH3 H Br O 5-Fluorouracil H 0-amino acid CH3 H Br 0 8-Fluoroguanine H 0-amino acid CH3 H Br O 5-Fluorocytosine H O-amino acid CH3 H Br O 8-Fluoroadenine H O-amino acid CH3 H Br O 2-Fluoroadenine H O-amino acid CH3 H Br O 2, 8-Difluoroadenine H O-amino acid CH3 H Br O 2-Fluorohypoxanthine H O-amino acid CH3 H Br 0 8-Fluorohypoxanthine H 0-amino acid CH3 H Br O 2, 8-Difluorohy oxanthine H O-amino acid CH3 H Br O 2-Aminoadenine H O-amino acid CH3 H Br O 2-Amino-8-fluoroadenine H O-amino acid CH3 H Br O 2-Amino-8-fluorohypoxanthine H O-amino acid CH3 H Br 0 2-Aminohypoxanthine H 0-amino acid CH3 H Br O 2-N-acetylguanine H O-amino acid CH3 H Br O 4-N-acetylcytosine H O-amino acid CH3 H Br O 6-N-acetyladenine H O-amino acid CH3 H Br O 2-N-acetyl-8-fluoroguanine H O-amino acid CH3 H Br O 4-N-acetyl-5-fluorocytosine H O-amino acid CH3 H Br O 6-N-acetyl-2-fluoroadenine H O-amino acid CH3 H Br O 6-N-acet 1-2, 8-difluoroadenine H O-amino acid CH3 H Br 0 6-N-acetyl-2-aminoadenine H 0-amino acid CH3 H Br O 6-N-acetyl-2-amino-8-fluoroadenine H 0-amino acid CH3 H Br O 2-N-acetylaminoadenine H O-amino acid CH3 H Br O 2-N-acetylamino-8-fluoroadenine H O-amino acid CH3 H Br 0 2-N-acetylamino-8-fluorohypoxanthine H 0-amino acid CH3 H Br O 2-N-acet laminoh oxanthine H O-amino acid CH3 H Br 0 Thymine H 0-acyl CH3 H Br O Uracil H O-acyl CH3 H Br O Guanine H O-acyl CH3 H Br O Cytosine H O-acyl CH3 H Br O Adenine H O-acyl CH3 H Br 0 Hypoxanthine H 0-acyl CH3 H Br O 5-Fluorouracil H O-acyl CH3 H Br O 8-Fluoroguanine H O-acyl CH3 H Br O 5-Fluorocytosine H O-acyl v H3 H Br O 8-Fluoroadenine H O-acyl CH3 H Br O 2-Fluoroadenine H O-acyl CH3 H Br O 2, 8-Difluoroadenine H O-acyl CH3 H Br O 2-Fluorohy oxanthine H O-acyl CH3 H Br O 8-Fluorohypoxanthine H O-acY CH3 H Br O 2, 8-Difluorohypoxanthine H 0-acyl CH3 H Br O 2-Aminoadenine H O-acyl R R R X Base R R CH3 H Br O 2-Amino-8-fluoroadenine H O-acyl CH3 H Br O 2-Amino-8-fluorohypoxanthine H O-acyl CH3 H Br 0 2-Aminohypoxanthine H 0-acyl CH3 H Br 0 2-N-acetyl guanine H 0-acyl CH3 H Br O 4-N-acetylcytosine H O-acyl CH3 H Br 0 6-N-acetyladenine H 0-acyl CH3 H Br O 2-N-acet 1-8-fluoroguanine H O-acyl CH3 H Br O 4-N-acetyl-5-fluorocytosine H O-acyl CH3 H Br O 6-N-acetyl-2-fluoroadenine H O-acyl CH3 H Br 0 6-N-acetyl-2, 8-difluoroadenine H 0-acyl CH3 H Br O 6-N-acetyl-2-aminoadenine H O-acyl CH3 H Br O 6-N-acetyl-2-amino-8-fluoroadenine H O-acyl CH3 H Br O 2-N-acetylaminoadenine H O-acyl CH3 H Br O 2-N-acetylamino-8-fluoroadenine H O-acyl CH3 H Br O 2-N-acetylamino-8-fluorohypoxanthine H O-acyl CH3 H Br O 2-N-acetylaminohypoxanthine H O-acyl CH3 H Cl O Thymine F O-amino acid CH3 H Cl O Uracil F O-amino acid CH3 H Cl O Guanine F O-amino acid CH3 H Cl O Cytosine F O-amino acid CH3 H Cl O Adenine F O-amino acid CH3 H Cl O Hypoxanthine F O-amino acid CH3 H Cl O 5-Fluorouracil F O-amino acid CH3 H Cl O 8-Fluoroguanine F O-amino acid CH3 H Cl O 5-Fluorocytosine F O-amino acid CH3 H Cl O 8-Fluoroadenine F O-amino acid CH3 H Cl O 2-Fluoroadenine F O-amino acid CH3 H Cl O 2, 8-Difluoroadenine F O-amino acid CH3 H Cl O 2-Fluorohypoxanthine F O-amino acid CH3 H CI O 8-Fluorohypoxanthine F O-amino acid CH3 H Cl O 2, 8-Difluorohypoxanthine F O-amino acid CH3 H Cl O 2-Aminoadenine F O-amino acid CH3 H Cl 0 2-Amino-8-fluoroadenine F 0-amino acid CH3 H Cl O 2-Amino-8-fluorohypoxanthine F O-amino acid CH3 H Cl O 2-Aminohypoxanthine F O-amino acid CH3 H Cl 0 2-N-acetylguanine F 0-amino acid CH3 H Cl O 4-N-acetylcytosine F O-amino acid CH3 H CI O 6-N-acetyladenine F O-amino acid CH3 H Cl O 2-N-acetyl-8-fluoroguanine F O-amino acid CH3 H Cl O 4-N-acetyl-5-fluorocytosine F O-amino acid CH3 H Cl O 6-N-acetyl-2-fluoroadenine F O-amino acid CH3 H Cl O 6-N-acetyl-2, 8-difluoroadenine F O-amino acid CH3 H Cl 0 6-N-acetyl-2-aminoadenine F 0-amino acid CH3 H Cl O 6-N-acetyl-2-amino-8-fluoroadenine F O-amino acid CH3 H Cl O 2-N-acetylaminoadenine F O-amino acid 3 H Cl O 2-N-acetylamino-8-fluoroadenine F O-amino acid CH3 H Cl O 2-N-acetylamino-8-fluorohypoxanthine F O-amino acid R6 R 7 R8 X Base Rl° R9 CH3 H Cl 0 2-N-acetylaminohypoxanthine F 0-amino acid CH3 H Cl O Thymine F O-acyl CH3 H Cl O Uracil F O-acyl CH3 H Cl O Guanine F O-acyl CH3 H Cl O Cytosine F O-acyl CH3 H Cl O Adenine F O-acyl CH3 H C1 O H oxanthine F O-ac 1 CH3 H Cl O 5-Fluorouracil F O-acyl CH3 H CI O 8-Fluoroguanine F O-acyl CH3 H Cl O 5-Fluorocytosine F O-acyl CH3 H Cl 0 8-Fluoroadenine F 0-acyl CH3 H Cl O 2-Fluoroadenine F O-acyl CH3 H Cl O 2, 8-Difluoroadenine F O-acyl CH3 H Cl O 2-Fluorohypoxanthine F O-acyl CH3 H Cl O 8-Fluorohypoxanthine F O-acyl CH3 H CI O 2, 8-Difluorohypoxanthine F 0-acyl CH3 H Cl O 2-Aminoadenine F O-acyl CH3 H Cl O 2-Amino-8-fluoroadenine F O-acyl CH3 H Cl O 2-Amino-8-fluorohypoxanthine F O-acyl CH3 H Cl O 2-Aminohy oxanthine F O-acyl CH3 H Cl O 2-N-acetylguanine F O-acyl CH3 H Cl O 4-N-acetylcytosine F O-ac 1 CH3 H Cl O 6-N-acetyladenine F O-acyl CH3 H Cl 0 2-N-acetyl-8-fluoroguanine F 0-acyl CH3 H Cl O 4-N-acetyl-5-fluorocytosine F O-acyl CH3 H Cl O 6-N-acetyl-2-fluoroadenine F O-acyl CH3 H Cl O 6-N-acetyl-2, 8-difluoroadenine F O-acyl CH3 H Cl O 6-N-acetyl-2-aminoadenine F O-acyl CH3 H Cl O 6-N-acetyl-2-amino-8-fluoroadenine F O-acyl CH3 H Cl O 2-N-acetylaminoadenine F 0-acyl CH3 H Cl O 2-N-acetylamino-8-fluoroadenine F O-acyl CH3 H Cl O 2-N-acetylamino-8-fluorohypoxanthine F O-acyl CH3 H Cl O 2-N-acetylaminohypoxanthine F O-acyl CH3 H Cl O Thymine Br O-amino acid CH3 H Cl O Uracil Br O-amino acid CH3 H Cl O Guanine Br O-amino acid CH3 H Cl 0 Cytosine Br 0-amino acid CH3 H Cl O Adenine Br O-amino acid CH3 H ci O Hypoxanthine Br O-amino acid CH3 H Cl O 5-Fluorouracil Br O-amino acid CH3 H Cl O 8-Fluoro uanine Br 0-amino acid CH3 H Cl O 5-Fluorocytosine Br O-amino acid CH3 H Cl O 8-Fluoroadenine Br O-amino acid CH3 H Cl O 2-Fluoroadenine Br O-amino acid CH3 H CI O 2, 8-Difluoroadenine Br O-amino acid CH3 H Cl O 2-Fluoroh oxanthine Br O-amino acid CH3 H Cl O 8-Fluorohypoxanthine Br O-amino acid R6 R 7 R8 X Base CH3 H CI O 2, 8-Difluorohypoxanthine Br O-amino acid CH3 H Cl O 2-Aminoadenine Br O-amino acid CH3 H Cl O 2-Amino-8-fluoroadenine Br O-amino acid CH3 H Cl O 2-Amino-8-fluorohypoxanthine Br O-amino acid CH3 H Cl O 2-Aminohypoxanthine Br O-amino acid CH3 H Cl O 2-N-acetylguanine Br O-amino acid CH3 H Cl O 4-N-acetylcytosine Br O-amino acid CH3 H Cl O 6-N-acetyladenine Br O-amino acid CH3 H Cl O 2-N-acetyl-8-fluoroguanine Br O-amino acid CH3 H Cl O 4-N-acetyl-5-fluorocytosine Br O-amino acid CH3 H CI O 6-N-acetyl-2-fluoroadenine Br O-amino acid CH3 H Cl O 6-N-acetyl-2, 8-difluoroadenine Br O-amino acid CH3 H Cl O 6-N-acetyl-2-aminoadenine Br O-amino acid CH3 H Cl O 6-N-acetyl-2-amino-8-fluoroadenine Br O-amino acid CH3 H Cl O 2-N-acetylaminoadenine Br O-amino acid CH3 H Cl O 2-N-acetylamino-8-fluoroadenine Br O-amino acid CH3 H Cl O 2-N-acetylamino-8-fluorohypoxanthine Br O-amino acid CH3 H C1 O 2-N-acetylaminohy oxanthine Br O-amino acid CH3 H C1 O Thymine Br O-acyl CH3 H Cl O Uracil Br O-acyl CH3 H Cl O Guanine Br O-acyl CH3 H Cl O Cytosine Br O-acyl CH3 Cl O Adenine Br O-acyl CH3 H Cl O Hypoxanthine Br 0-acyl CH3 Cl O 5-Fluorouracil Br O-acyl CH3 H Cl O 8-Fluoroguanine Br O-acyl CH3 H CI O 5-Fluorocytosine Br O-ac I CH3 H Cl O 8-Fluoroadenine Br O-acyl CH3 H Cl O 2-Fluoroadenine Br O-acyl CH3 H Cl O 2, 8-Difluoroadenine Br O-acyl CH3 H Cl O 2-Fluorohypoxanthine Br O-acYI CH3 H C I O 8-Fluorohypoxanth ine Br O-acyl CH3 H Cl O 2, 8-Difluorohypoxanthine Br O-ac I CH3 H Cl O 2-Aminoadenine Br O-acyl CH3 H Cl O 2-Amino-8-fluoroadenine Br O-acyl CH3 H Cl O 2-Amino-8-fluorohypoxanthine Br O-acyl CH3 H Cl O 2-Aminohypoxanthine Br O-acyl CH3 H Cl O 2-N-acetylguanine Br O-acyl CH3 H Cl 0 4-N-acetylcytosine Br O-acyl CH3 H CI 0 6-N-acetyladenine Br 0-acyl CH3 H Cl O 2-N-acetyl-8-fluoroguanine Br O-acyl CH3 H CI 0 4-N-acetyl-5-fluorocytosine Br O-acyl CH3 H Cl O 6-N-acetyl-2-fluoroadenine Br O-acyl CH3 H Cl O 6-N-acetyl-2, 8-difluoroadenine Br 0-acyl CH3 H Cl O 6-N-acetyl-2-aminoadenine Br O-acyl CH3 H Cl O 6-N-acetyl-2-am ino-8-fluoroadenine Br O-acyl CH3 H Cl O 2-N-acetylaminoadenine Br O-acyl R R R X Base | Rl° 89 CH3 H Cl O 2-N-acetylamino-8-fluoroadenine Br O-acyl CH3 H Cl O 2-N-acetylamino-8-fluorohypoxanthine Br O-acyl CH3 H Cl O 2-N-acetylaminohypoxanthine Br O-acyl CH3 H Cl O Thymine Cl O-amino acid CH3 H Cl O Uracil Cl O-amino acid CH3 H Cl O Guanine Cl O-amino acid CH3 H Cl O Cytosine Cl O-amino acid CH3 H Cl O Adenine Cl O-amino acid CH3 H Cl O Hypoxanthine Cl O-amino acid CH3 H CI O 5-Fluorouracil Cl O-amino acid CH3 H Cl O 8-Fluoroguanine Cl O-amino acid CH3 H Cl O 5-Fluorocytosine Cl O-amino acid CH3 H Cl O 8-Fluoroadenine Cl O-amino acid CH3 H Cl O 2-Fluoroadenine Cl O-amino acid CH3 H Cl O 2, 8-Difluoroadenine Cl O-amino acid CH3 H Cl O 2-Fluorohypoxanthine Cl O-amino acid CH3 H Cl O 8-Fluorohypoxanthine Cl O-amino acid CH3 H Cl O 2, 8-Difluorohypoxanthine Cl O-amino acid CH3 H CI O 2-Aminoadenine Cl O-amino acid CH3 H Cl O 2-Amino-8-fluoroadenine Cl O-amino acid CH3 H Cl O 2-Amino-8-fluorohypoxanthine Cl O-am ino acid CH3 H Cl O 2-Aminohypoxanthine Cl 0-amino acid CH3 H Cl 0 2-N-acetylguanine Cl 0-amino acid CH3 H Cl O 4-N-acetylcytosine Cl O-amino acid CH3 H Cl O 6-N-acetyladenine Cl O-amino acid CH3 H Cl O 2-N-acet 1-8-fluoroguanine CI O-amino acid CH3 H Cl O 4-N-acetyl-5-fluorocytosine Cl O-amino acid CH3 H C1 O 6-N-acetyl-2-fluoroadenine Cl O-amino acid CH3 H Cl O 6-N-acetyl-2, 8-difluoroadenine Cl O-amino acid CH3 H Cl 0 6-N-acetyl-2-aminoadenine Cl 0-amino acid CH3 H Cl O 6-N-acetyl-2-amino-8-fluoroadenine Cl O-amino acid CH3 H Cl O 2-N-acetylaminoadenine Cl O-amino acid CH3 Cl O 2-N-acetylamino-8-fluoroadenine Cl O-amino acid CH3 H Cl O 2-N-acetylamino-8-fluorohypoxanthine Cl O-amino acid CH3 H Cl O 2-N-acetylaminohypoxanthine Cl O-amino acid CH3 Cl O Thymine Cl O-acyl CH3 H Cl O Uracil Cl O-acyl CH3 H _ Cl O Guanine Cl O-acyl CH3 H Cl O Cytosine Cl O-acyl CH3 HC) 0 AdenineJCj0-acyl CH3 H Cl O Hypoxanthine Cl O-acyl CH3 H CI O 5-Fluorouracil Cl O-acyl CH3 H Cl O 8-Fluoroguanine Cl O-acyl CH3 H Cl O 5-Fluorocytosine Cl O-acyl CH3 H Cl O 8-Fluoroadenine Cl O-acyl CH3 H Cl O 2-Fluoroadenine Cl O-acyl CH3 Hot 0 2, 8-Difluoroadenine Cl O-acyl R6 R7 R8 X Base Rl° R9 CH3 H Cl O 2-Fluorohypoxanthine Cl O-acyl CH3 H Cl 0 8-Fluorohypoxanthine Cl 0-acyl CH3 Hot 0 2, 8-Difluorohypoxanthine Cl 0-acyl CH3 H Cl O 2-Aminoadenine Cl O-acyl CH3 H Cl O 2-Amino-8-fluoroadenine Cl O-acyl CH3 H Cl O 2-Amino-8-fluorohypoxanthine Cl O-acyl CH3 H Cl O 2-Aminohypoxanthine Cl O-acyl CH3 H Cl O 2-N-acetylguanine Cl O-acyl CH3 H Cl O 4-N-acetylcytosine Cl O-acyl CH3 H CI O 6-N-acetyladenine Cl O-acyl CH3 H Cl O 2-N-acetyl-8-fluoroguanine Cl O-acyl CH3 H Cl O 4-N-acetyl-5-fluorocytosine Cl 0-acyl CH3 H Cl O 6-N-acetyl-2-fluoroadenine Cl O-acyl CH3 H Cl O 6-N-acetyl-2, 8-difluoroadenine Cl 0-acyl CH3 H Cl O 6-N-acetyl-2-aminoadenine Cl O-acyl CH3 H Cl O 6-N-acetyl-2-amino-8-fluoroadenine Cl O-acyl CH3 H Cl O 2-N-acetylaminoadenine Cl O-acyl CH3 H Cl O 2-N-acetylamino-8-fluoroadenine Cl O-acyl CH3 H Cl O 2-N-acetylamino-8-fluorohypoxanthine Cl O-acyl CH3 H Cl O 2-N-acetylaminohypoxanthine Cl O-acyl CH3 H Cl O Thymine H O-amino acid CH3 H Cl O Uracil H O-amino acid CH3 H Cl O Guanine H O-amino acid CH3 H Cl O Cytosine H O-amino acid CH3 H Cl O Adenine H O-amino acid CH3 H Cl O Hypoxanthine H O-amino acid CH3 H Cl O 5-Fluorouracil H O-amino acid CH3 Cl O 8-Fluoroguanine H O-amino acid CH3 H Cl O 5-Fluorocytosine H O-amino acid CH3 H Cl O 8-Fluoroadenine H O-amino acid CH3 H Cl O 2-Fluoroadenine H O-amino acid CH3 H Cl O 2, 8-Difluoroadenine H O-amino acid CH3 H Cl O 2-Fluorohypoxanthine H O-amino acid CH3 H Cl O 8-Fluorohypoxanthine H 0-mino acid CH3 H CI O 2, 8-Difluorohypoxanthine H O-amino acid CH3 H Cl O 2-Aminoadenine H O-amino acid CH3 H Cl O 2-Amino-8-fluoroadenine H O-amino acid CH3 H Cl O 2-Amino-8-fluorohy oxanthine H O-amino acid CH3 H Cl O 2-Aminohypoxanthine H O-amino acid CH3 H Cl O 2-N-acetyl guanine 0-amino acid CH3 H Cl O 4-N-acetylcytosine H O-amino acid CH3 H Cl O 6-N-acetyladenine H O-amino acid CH3 H Cl 0 2-N-acetyl-8-fluoroguanine H 0-amino acid CH3 H Cl O 4-N-acetyl-5-fluoroc osine H O-amino acid CH3 H Cl O 6-N-acetyl-2-fluoroadenine H O-amino acid CH3 H Cl O 6-N-acetyl-2, 8-difluoroadenine H O-amino acid CH3 H Cl O 6-N-acetyl-2-aminoadenine H O-amino acid R R R X Base f R9 CH3 H Cl O 6-N-acetyl-2-amino-8-fluoroadenine H O-amino acid CH3 H Cl O 2-N-acetylaminoadenine H O-amino acid CH3 H Cl O 2-N-acetylamino-8-fluoroadenine H O-amino acid CH3 H Cl O 2-N-acetylamino-8-fluorohypoxanthine H O-amino acid CH3 H Cl O 2-N-acetylaminohypoxanthine H 0-amino acid CH3 H Cl O Thymine H O-acyl CH3 H Cl O Uracil H 0-acyl CH3 H Cl O Guanine H O-acyl CH3 H Cl O Cytosine H O-ac 1 CH3 H Cl O Adenine H O-ac 1 CH3 H Cl O Hypoxanthine H 0-acyl CH3 H Cl O 5-Fluorouracil H O-acyl CH3 H Cl O 8-Fluoroguanine H O-acyl CH3 H Cl O 5-Fluorocytosine H O-acyl CH3 H CI O 8-Fluoroadenine H O-acyl CH3 H Cl O 2-Fluoroadenine H O-acyl CH3 H Cl O 2, 8-Difluoroadenine H O-acyl CH3 H Cl O 2-Fluorohypoxanthine H 0-acyl CH3 H Cl O 8-Fluorohypoxanthine H O-acyl CH3 H Cl O 2, 8-Difluorohypoxanthine H O-acyl CH3 H Cl O 2-Aminoadenine H O-acyl CH3 H Cl O 2-Amino-8-fluoroadenine H O-acyl CH3 H Cl O 2-Amino-8-fluorohypoxanthine H 0-acyl CH3 H CI O 2-Aminohypoxanthine H O-acyl CH3 H Cl O 2-N-acetyl guanine H 0-acyl CH3 H Cl O 4-N-acetylcytosine H O-acyl CH3 H Cl O 6-N-acetyladenine H O-acyl CH3 H Cl O 2-N-acet 1-8-fluoro uanine H O-ac 1 CH3 H Cl O 4-N-acetyl-5-fluorocytosine H O-acyl CH3 H Cl O 6-N-acetyl-2-fluoroadenine H O-ac 1 CH3 H Cl O 6-N-acetyl-2, 8-difluoroadenine H O-acyl CH3 H Cl O 6-N-acetyl-2-aminoadenine H O-acyl CH3 H Cl O 6-N-acetyl-2-amino-8-fluoroadenine H O-acyl CH3 H Cl O 2-N-acetylaminoadenine H O-acyl CH3 H Cl O 2-N-acetylamino-8-fluoroadenine H O-acyl CH3 H Cl O 2-N-acetylamino-8-fluorohypoxanthine H O-acyl CH3 H Cl O 2-N-acetylaminohypoxanthine H O-acyl CH3 H H O Thymine F O-amino acid CH3 H H O Uracil F O-amino acid CH3 H H O Guanine F O-amino acid CH3 H H O Cytosine F O-amino acid CH3 H H O Adenine F O-amino acid CH3 H H O Hypoxanthine F O-amino acid CH3 H H O 5-Fluorouracil F O-amino acid CH3 H H 0 8-Fluoroguanine F 0-amino acid CH3 H H O 5-Fluorocytosine F O-amino acid H H H O 8-Fluoroadenine F O-amino acid R R R X Base R ray CH3 H H O 2-Fluoroadenine F O-amino acid CH3 H H 0 2, 8-DifluoroadenineF0-amino acid CH3 H H 0 2-Fluorohypoxanthine F O-amino acid CHs HJH0 8-FluorohypoxanthineJP0-amino acid CH3 H H 0 2, 8-Difluorohypoxanthine F O-amino acid CH3 H H 0 2-Aminoadenine F 0-amino acid CH3 H H 0 2-Amino-8-fluoroadenine F O-amino acid CH3 H H 0 2-Amino-8-fluorohypoxanthine F O-amino acid CH3 H H O 2-Aminohypoxanthine F O-amino acid CH3 H H 0 2-N-acetyl guanine F 0-amino acid CH3 H H 0 4-N-acetylcytosine F 0-amino acid CH3 H H O 6-N-ace ladenine F O-amino acid CH3 H H 0 2-N-acetyl-8-fluoroguanine F O-amino acid CH3 H H O 4-N-acetyl-5-fluorocytosine F O-amino acid CH3 H H O 6-N-acetyI-2-fluoroadenine F O-amino acid CH3 H H O 6-N-acetyl-2, 8-difluoroadenine F O-amino acid CH3 H H 0 6-N-acetyl-2-aminoadenine F O-amino acid CH3 H H 0 6-N-acetyl-2-amino-8-fluoroadenine F O-amino acid CH3 H H 0 2-N-acetylaminoadenine F O-amino acid CH3 H H 0 2-N-acetylamino-8-fluoroadenine F O-amino acid CH3 H H 0 2-N-acetylamino-8-fluorohypoxanthine F 0-amino acid CH3 H H 0 2-N-acetylaminohypoxanthine F O-amino acid CH3 H H O Thymine F O-acyl CH3 H H O Uracil F 0-acyl CH3 H H 0 Guanine F 0-acyl CH3 H H O C osine F O-acy1 CH3 H H O Adenine F O-acy1 CH3 H H O Hypoxanthine F O-acy1 CH3 HJH0 5-FtuorouracitF0-acyt CH3 H H 0 8-Fluoroguanine F 0-acyl CH3 HJH0 5-F ! uorocytosineF0-acyt CH3 H H 0 8-Fluoroadenine F 0-acyi CH3 H H 0 2-Fluoroadenine F 0-acyl CH3 H H O 2, 8-Difluoroadenine F O-acy1 CH3 H H 0 2-Fluorohypoxanthine F 0-acyl CH3 H H 10 8-Fluorohypoxanthine F 0-acyl CH3 H H 0 2, 8-Difluorohypoxanthine F O-acyl CH3 H H O 2-Aminoadenine F O-acy1 CH3 H H O 2-Amino-8-fluoroadenine F O-acy1 CH3 H H O 2-Amino-8-fluorohypoxanthine F O-acyl CH3 H H O 2-Aminohypoxanthine F O-acyl CH3 H H 0 2-N-acetylguanine F 0-cyl CH3 H H O 4-N-acetylcytosine F O-acyl CH3 H H 0 6-N-acetyladenine F 0-acyl CH3 H H O 2-N-acetyl-8-fluoroguanine F O-acy1 CH3 H H O 4-N-acety1-5-fluorocytosine F O-acy1 CH3 H H O 6-N-acetyl-2-fluoroadenine F O-acyl R R'R X Base R R CH3 H H 0 6-N-acetyl-2, 8-difluoroadenine F O-acyl CH3 H H 0 6-N-acetyl-2-aminoadenine F 0-acyl CH3 H H 0 6-N-acetyl-2-amino-8-fluoroadenine F 0-acyl CH3 H H 0 2-N-acetylaminoadenine F 0-acyl CH3 H H O 2-N-acet lamino-8-fluoroadenine F O-acyl CH3 H H 0 2-N-acetylamino-8-fluorohypoxanthine F 0-acyl CH3 H H 0 2-N-acetylaminohypoxanthine F 0-acyl CH3 H H O Thymine Br O-amino acid CH3 H H O Uracil Br O-amino acid CH3 H H O Guanine Br O-amino acid CH3 H H O Cytosine Br O-amino acid CH3 H H O Adenine Br O-amino acid CH3 H H 0 Hypoxanthine Br 0-amino acid CH3 H H O 5-Fluorouracil Br 0-amino acid CH3 H H O 8-Fluoroguanine Br O-amino acid CH3 H H O 5-Fluorocytosine Br O-amino acid CH3 H H O 8-Fluoroadenine Br O-amino acid CH3 H H O 2-Fluoroadenine Br O-amino acid CH3 H H O 2, 8-Difluoroadenine Br O-amino acid CH3 H H O 2-Fluorohypoxanthine Br O-amino acid CH3 H H O 8-Fluorohypoxanthine Br O-amino acid CH3 H H O 2, 8-Difluoroh oxanthine Br O-amino acid CH3 H H O 2-Aminoadenine Br O-amino acid CH3 H H O 2-Amino-8-fluoroadenine Br O-amino acid CH3 H H O 2-Amino-8-fluorohypoxanthine Br O-amino acid CH3 H H 0 2-Aminohypoxanthine Br 0-amino acid CH3 H H O 2-N-acetylguanine Br O-amino acid CH3 H H O 4-N-acetyIcytosine Br O-amino acid CH3 H H O 6-N-acetyladenine Br O-amino acid CH3 H H O 2-N-acetyl-8-fluoroguanine Br O-amino acid CH3 H H O 4-N-acetyl-5-fluorocytosine Br O-amino acid CH3 H H O 6-N-acetyl-2-fluoroadenine Br O-amino acid CH3 H H O 6-N-acetyl-2, 8-difluoroadenine Br O-amino acid CH3 H H O 6-N-acetyl-2-aminoadenine Br O-amino acid CH3 H H O 6-N-acetyl-2-amino-8-fluoroadenine Br O-amino acid CH3 H H O 2-N-acetylaminoadenine Br O-amino acid CH3 H H O 2-N-acetylamino-8-fluoroadenine Br O-amino acid CH3 H H O 2-N-acetylamino-8-fluorohypoxanthine Br 0-amino acid CH3 H H O 2-N-acetylaminohypoxanthine Br O-amino acid CH3 H H O Thymine Br O-acyl CH3 H H O Uracil Br O-acyl CH3 H H O Guanine Br O-acyl CH3 H H O Cytosine Br O-acyl CH3 H H O Adenine Br O-acyl CH3 H H O Hypoxanthine Br O-acyl CH3 H H O 5-Fluorouracil Br O-ac 1 CH3 H H O 8-Fluoro uanine Br O-acyl R R7 T X Base F R9 CH3 H H O 5-Fluoroc osine Br O-ac 1 CH3 H H O 8-Fluoroadenine Br O-acyl CH3 H H O 2-Fluoroadenine Br O-acyl CH3 H H O 2, 8-Difluoroadenine Br O-acyl CH3 H H O 2-Fluorohypoxanthine Br O-acyl CH3 H H O 8-Fluoroh oxanthine Br O-ac 1 CH3 H H O 2, 8-Difluorohypoxanthine Br O-acyl CH3 H H O 2-Aminoadenine Br O-ac 1 CH3 H H O 2-Amino-8-fluoroadenine Br O-ac I CH3 H H O 2-Amino-8-fluorohypoxanthine Br O-acyl CH3 H H 0 2-Aminohypoxanthine Br 0-acyl CH3 H H 0 2-N-acetylguanine Br 0-acyl CH3 H H O 4-N-acet lc osine Br O-ac 1 CH3 H H O 6-N-acetyladenine Br O-acyl CH3 H H 0 2-N-acetyl-8-fluoroguanine Br 0-acyl CH3 H H O 4-N-acetyl-5-fluorocytosine Br O-acyl CH3 H H O 6-N-acetyl-2-fluoroadenine Br O-acyl CH3 H H O 6-N-acetyl-2, 8-difluoroadenine Br O-acyl CH3 H H O 6-N-acetyl-2-aminoadenine Br O-acyl CH3 H H O 6-N-acet 1-2-amino-8-fluoroadenine Br O-acyl CH3 H H O 2-N-acetylaminoadenine Br O-acyl CH3 H H O 2-N-acetylamino-8-fluoroadenine Br O-acyl CH3 H H O 2-N-acetylamino-8-fluorohypoxanthine Br O-acyl CH3 H H O 2-N-acetylaminohy oxanthine Br O-acyl CH3 H H O Thymine Cl O-amino acid