BACKGROUND OF THE INVENTION [0002] Nucleoside triphosphate compounds may be polymerized to provide ribonucleic acid (RNA) and deoxyribonucleic acid (DNA). Apart from the traditional role in normal cells these nucleic acids form the genetic materials of a variety of pathogenic viruses such as HIV, herpes, measles, mumps and many others.

[0003] Simoncsits, A. and Tomasz, J., Tetrahedron Letters 1976,44, 3995- 3998, reported the synthesis of a 5'-triphosphate derivative by selective replacement of one of the two amide groups of 5'-phosphorodiamidates. J. Ludwig, Acta Biochim. et Biophys. Acad. Sci. IIung, 1981,16, 131-133, suggests a method of making 5'- triphosphates by treatment in situ with excess tri-n-butylammonium pyrophosphate in DMF under anhydrous conditions followed by neutral hydrolysis.

[0004] Many nucleoside triphosphates are not particularly robust because of the difficulty in making quantitative judgments about their rates of decomposition.

They also tend to be difficult to synthesize with many methods utilizing combinations of charged ionic reagents with more lypophilic substrates, such as pyrophosphates and protected nucleosides, respectively. According to Burgess, K. & Cook, D., Chemin.

Rev. 2000,100 2047-2059, many current methods are unable to provide high-yielding routes to synthesizing nucleoside triphosphates that are capable of allowing a diverse set of nucleoside triphosphates to be made via a combinatorial or high throughput par- allel synthesis. Ludwig J. and Eckstein F., J. Org. Chez., 1989,54, 631-635, disclose a method of making nucleoside 5'-triphosphates and a-thio analogues that requires the protection of the ribose 2'and 3'hydroxyl groups and produces hard to remove by products. R. K. Gaur, B. S. Sproat, G. Krupp, Tetrahedron Letters 1992,33, 3301- 3304, disclose a method of making a 5'-triphosphate that requires the attachment of a functionalized solid support that serves as an anchor and protecting group throughout all of the chemical manipulations. This synthesis method also results in modest yield of a-thiotriphosphates that may be the result of an incomplete sulphurisation step.

[0005] The oc-P substitutions in nucleoside triphosphate analogues are useful in elucidation of the enzymic functions and mechanisms. Nucleoside 5'-(oFP-(N- <BR> <BR> alkyl) -nucleoside triphosphates are modified nucleotides in which one of the oc- phosphate oxygens is replaced by a primary amine. Exchange of one of the a- phosphate oxygens for sulfur, borane or methyl has also proven to be useful in inves- tigations of the stereochemical course of enzymic reactions. (See Eckstein, F. Ann.

Rev. Biochem. 1985,54, 367-402; Kaizhang, H., et al. J. Org. Chenu. 1998,63, 5769- 5773; Victorova, L. S., Nucleic Acids Research 1992,20, 783-789). oc-Modified nu- cleoside triphosphate analogs are disclosed in International Application Number PCT/USOO/22802, published March 1,2001.

[0006] K. Mori. et al., Nucleic Acids Research 1978,5, 2945-2957, attempted to test phosphorochalcogenoate derivatives in which selenium replaces one of the phosphate oxygens by substituting one of the non-bridging oxygen atoms with seb- nium using potassium selenocyanoate as the selenium donor. Stawinski, J. , and M.

Thelin, J. Org Chem. 1994,59, 130-136, disclosed a method of synthesizing dinu- cleoside phosphoroselenoates through use of a selenium transferring reagent to con- vert nucleoside H-phosphoroate & H-phosphonothioate diester into their correspond- ing phosphoroselenoates and phosphorothioselenoates. Brownlee, G., et al. Nucleic Acid Research 1995,23, 2641-2647, developed a solid phase method of synthesizing 5'-diphosphorylated oligoribonucleotides in preparing capped oligonucleotides. Ny- ilas, A., Tetrahedron Letters 1997,38, 2517-1518, disclosed a one pot synthesis ofy- amidite by opening cyclic trimetaphosphate with different amines. Krzyzanowska, R. <BR> <BR> <P>K. , et al., Tetrahedron 1998,54, 5119-5128, adapted the Ludwig and Eckstein, supra, method to create a one pot procedure for synthesizing 2'-deoxyribonucleoside 5'- (a- P-Borano) triphosphates.

[0007] In cellular processes, nucleotide triphosphate compounds can be used as intermediates in the biosynthesis of nucleosides, proteins and hormones. As a pharmacologic target, nucleotide triphosphates are difficult because of the hydrolytic lability of the triphosphate and related intermediates and also due to the short half life related to these compounds. In short they are widely useful per se.

[0008] A wider variety of modified nucleoside triphosphate compounds is needed including those that mimic natural analogs that have desired downstream pharmacologic effects not elicited by modified compounds. Other properties desir- able in such modified nucleoside triphosphate compounds include increased hydro- lytic stability in cellular systems and low toxicity.

[0009] Accordingly, it is the object of this invention to provide new solid phase methods of preparing dithio triphosphates from cyclic triphosphates.

[0010] It is also an object of this invention to provide new solid phase meth- ods of preparing a-borano-a-thio triphosphates, a-borano triphosphates, oc-seleno triphosphates, a-amino triphosphates and a-substituted amino triphosphates.

[0011] It is yet another object of this invention to provide new 2'-Sugar substituent groups for nucleic acids.

BRIEF DESCRIPTION OF THE DRAWINGS [0012] The numerous objects and advantages of the present invention may be better understood by those skilled in the art by reference to the accompanying detailed description and the following drawings, in which: SUMMARY OF THE INVENTION [0013] Applicants have discovered methods that are useful in, for example, the preparation of a-modified nucleoside triphosphates. According to one embodiment, there are methods providing nucleoside triphosphate compounds of formula I: wherein: Y, is Se and Y2 is OH or SH; or Y, is O and YZ is NHRI or BH3 ; or Y, is S and Y2 is NHR,, SH or BH3 ; and Y3 is OH; NHRl ; alkyl or alkoxy; R, is hydrogen, substituted or unsubstituted Cl-Cl2 alkyl, substituted or unsub- stituted C2-Cl2 alkenyl, substituted or unsubstituted CfCl2 alkynyl, substituted or un- substituted C5 to C7 cyclic alkyl, substituted or unsubstituted Cs-C20 alkyaryl, substi- tuted or unsubstituted heterocyclyl, or a nitrogen protecting group, wherein said sub- stituent is substituted or unsubstituted CfC20 aryl, 0-alkyl, 0-alkylalkoxy, O- alkylaminoalkyl, 0-alkyl imidazole, S-alkyl, NH-alkyl, N-dialkyl, aryl, heterocycle, substituted heterocycle, 0-aryl, S-aryl, NH-aryl, 0-aralkyl, S-aralkyl, or NH-aralkyl ; one of X, and X2 is H, hydroxyl, a protected hydroxyl, or a sugar substituent group and the other of X2 and Xl is-O-J-SM ; Bx is an optionally protected heterocyclic base moiety; one of X, and X2 is H, hydroxyl, a protected hydroxyl, or a sugar substituent group and the other of X, and X2 is hydroxyl, a protected hydroxyl or-0-J-SM ; J is a bifunctional linking moiety; and SM is a support medium; comprising the steps of : a) providing a nucleosidyl-5'-cyclotriphosphite having the formula II: wherein: one of X2 and Xi is H, hydroxyl, a protected hydroxyl, or a sugar sub- stituent group and the other of X2 and Xl is-O-J-SM ; b) reacting said nucleosidyl-5'-cyclotriphosphite with an oxidizing reagent for a time and under conditions effective to give an oxidized compound hav- ing the formula III: wherein: Z is Se, S, BH3, or N-HR, ; e) treating said oxidized compound with a ring opening reagent effective to give compound I.

[0014] In another embodiment, compounds of formula I are provided wherein: Yl is Se and Y2 is OH or SH; or Y, is O and YZ is NHRI or BH ; or Y1 is S and Y2is NHRI, SH or BH3 ; and Y3 is OH; NHR, ; alkyl or alkoxy; R, is hydrogen, substituted or unsubstituted Cl-Cl2 alkyl, substituted or unsub- stituted C2-Cl2 alkenyl, substituted or unsubstituted CZ C, Z alkynyl, substituted or un- substituted Cs to C7 cyclic alkyl, substituted or unsubstituted Cs-C20 alkyaryl, substi- tuted or unsubstituted heterocyclyl, or a nitrogen protecting group, wherein said sub- stituent is substituted or unsubstituted Cs-C20 aryl, 0-alkyl, O-alkylalkoxy, O- alkylaminoalkyl, 0-alkyl imidazole, S-alkyl, NH-alkyl, N-dialkyl, aryl, heterocycle, substituted heterocycle, 0-aryl, S-aryl, NH-aryl, 0-aralkyl, S-aralkyl, or NH-aralkyl ; Bx is an optionally protected heterocyclic base moiety; one of X, and X2 is H, hydroxyl, a protected hydroxyl, or a sugar substituent group and the other of Xi and X2 is hydroxyl, a protected hydroxyl or-O-J-SM ; J is a bifunctional linking moiety; and SM is a support medium; with the proviso that when Y2 is BH3 or NH2 then Y3 is other than OH.

[0015] Alternate embodiments of this invention exist wherein the oxidizing agent is mixture of I2 and NH3 in a suitable solvent or I2 and NH2R, in a suitable sol- vent. The solvent can also be 1,4-dioxane, THF, (MeO) 3PO, acetonitrile, DMF or formamide. In other embodiments which some may find favorable, R, is methyl, pro- pyl, butyl, methoxypropyl, methoxyethyl, methylthioethyl, methylthiopropyl, cyclopentyl, benzyl, 2,4-methoxybenzyl, phenylbenzyl, crown ether or 7- deazaguanine.

[0016] Many embodiments have an oxidizing agent that is a solution of 3H- 1, 2-benzothiaselenol-3-one dissolved in a suitable solvent. The solvent of some em- bodiments is a mixture of acetonitrile and triethylamine. That mixture may comprise from about 1% to about 30% triethyl amine in acetonitrile by volume. General em- bodiments can have oxidizing agents that are solutions of S in a mixture of suitable solvents. The mixture can comprise carbon disulfide, pyridine, and tryiethlyamine.

Another embodiment can have a borane-N, N-diisopropylethyl complex as oxidizing agent. The nucleosidyl-5'-cyclotriphosphite can be reacted with said oxidizing agent for up to about 3 hours in some embodiments or up to about 2 hours in others. In yet other embodiments, the reaction can take place for up to about 40 minutes.

[0017] In other general embodiments, the ring opening reagent is H20, NHR, or Li2S.

[0018] The invention also encompasses those versions further comprising treating the nucleoside triphosphate compound with a cleaving reagent to cleave the compound from the support medium. Other versions can exist wherein the treatment with the cleaving reagent removes protecting groups present on the heterocyclic base moiety. In yet another version there can be treatment of the compound with a depro- tecting reagent to remove protecting groups on the heterocyclic base moiety.

[0019] There can be compounds in many embodiments wherein Y, is Se and Y2 is OH; wherein Y, is O and Y, is NHR, wherein said Rl is other than H; wherein Y, is O and Y2 is NHRI ; wherein Yl is O and Y2 is BH3 or wherein Y ; is S and Y2 is SH.

[0020] Other embodiments of this invention provide compounds having the formula II: wherein: Bx is an optionally protected heterocyclic base moiety; one of Xl and X2 is H, hydroxyl, a protected hydroxyl, or a sugar sub- stituent group and the other of Xl and X2 is-O-J-SM ; J is a bifunctional linking moiety; and SM is a support medium.

[0021] There are other embodiment of compounds having the formula III: wherein: Z is Se, S, BH3, or NHR, ; Bx is an optionally protected heterocyclic base moiety; one of X, and X2 is H, hydroxyl, a protected hydroxyl, or a sugar sub- stituent group and the other of Xl and X2 is-O-J-SM ; J is a bifunctional linking moiety; and SM is a support medium.

[0022] According to one embodiment of the present invention, there are meth- ods provided for preparing a-modified nucleoside triphosphates using support bound cyclic triphosphite nucleosides. The support bound cyclic triphosphite nucleoside is oxidized with an amino, seleno, borano or thio agent followed by treatment with a le- agent effective to open the cyclic functionality and give the support bound a-modified triphosphate nucleoside. Oxidizing a support bound cyclic triphosphite nucleoside which is further treated with a reagent effective to give the corresponding support bound nucleoside triphosphate which is cleaved and purified to give the free nucleo- side triphosphate.

[0023] In another embodiment of the present invention, a-modified triphos- phate nucleosides are provided. Further modified a-modified triphosphate nucleo- sides are provided comprising modifications on the nucleoside and/or the y-position of the triphosphate. a-Modified triphosphate nucleosides of the present invention in- clude those having the formula: Y, is Se and Y2 is OH or SH; or Yl is O and Y2is NHR, or BH3 ; or Yl is S and Y2 is NHRl, SH or BH3 ; Y3 is OH; NHR, ; alkyl or alkoxy; Ri is hydrogen, substituted or unsubstituted Cl-Cl2 alkyl, substituted or unsub- stituted C2-Cl2 alkenyl, substituted or unsubstituted CZ C, 2 alkynyl, substituted or un- substituted Cs to C7 cyclic alkyl, substituted or unsubstitutedC5-C2o alkyaryl, substi- tuted or unsubstituted heterocyclyl, or a nitrogen protecting group, wherein said sub- stituent is substituted or unsubstituted CfC20 aryl, 0-alkyl, O-alkylalkoxy, 0- alkylaminoalkyl, 0-alkyl imidazole, S-alkyl, NH-alkyl, N-dialkyl, aryl, heterocycle, substituted heterocycle, 0-aryl, S-aryl, NH-aryl, 0-aralkyl, S-aralkyl, or N-aralkyl ; Bx is an optionally protected heterocyclic base moiety ; one of X, and X2 is H, hydroxyl, a protected hydroxyl, or a sugar substituent group and the other of X, and X2 is hydroxyl, a protected hydroxyl or-O-J-SM ; J is a bifunctional linking moiety; and SM is a support medium; with the proviso that when Y2 is BH3 or NH2 then Y3 is other than OH.

[0024] Some of the a-modified nucleoside triphosphates provided by this in- vention have one of the a-phosphate oxygens exchanged for sulfur, borane, selenium, amine or alkyl. Many embodiments can be used as model compounds for research on enzyme functions and mechanisms of action. Such research and mechanisms may include stereochemical course of a variety of NTP based enzymic reaction and metal ion dependance for diastereomeric forms of a-P substituted anologues of nucleoside 5'-triphosphates. Others can be also used in construction of potential therapeutic agents and pro-drugs, working as reversible and irreversible inhibitors, transition state analogues, suicide substrates and also spectroscopic probes. In some general em- bodiments, the modified triphosphates can be used in direct sequencing by incorpora- tion of 2'-deoxynucleoside 5'-O- (a-P-boranothio) triphosphates into PCR products followed by chemical degradation in order to reveal their positions.

[0025] In one embodiment of the present invention amino functional groups are covalently attached to the a-position of modified triphosphate nucleosides. In an- other embodiment the amino functional group is covalently attached to the y-position of the a-modified triphosphate nucleoside. An amino functional group according to the present invention includes compounds having the formula-NHR,. Where R, in- cludes hydrogen, substituted or unsubstituted Cl-Cl2 alkyl, substituted or unsubsi- tuted C2-Cl2 alkenyl, substituted or unsubstituted CfCl2 alkynyl, substituted or unsub- stituted C5 to C7 cyclic alkyl, substituted or unsubstituted C5-C20 alkyaryl, substituted or unsubstituted heterocyclyl, or a nitrogen protecting group, wherein said substituent is substituted or unsubstituted CfC20 aryl, 0-alkyl, O-alkylalkoxy, O-alkylamino- alkyl, 0-alkyl imidazole, S-alkyl, NH-alkyl, N-dialkyl, aryl, heterocycle, substituted heterocycle, 0-aryl, S-aryl, NH-aryl, 0-aralkyl, S-aralkyl, or NH-aralkyl.

[0026] ° Some of the alkylamino functional groups attached to the a-phosphate have been shown to block the ionized phosphate. This aspect allows the invention to have control, and modification of liphophilic and steric properties of synthesized tri- phosphate analogues.

[0027] A heterocyclic base moiety (often referred to in the art simply as a "base"or a"nucleobase") amenable to the present invention includes both naturally and non-naturally occurring nucleobases. The heterocyclic base moiety further may be protected wherein one or more functionalities of the base bears a protecting group.

As used herein,"unmodified"or"natural"nucleobases include the purine bases ados- nine and guanine, and the pyrimidine bases thymine, cytosine and uracil. Modified nucleobases include other synthetic and natural nucleobases such as 5-methylcytosine (5-me-C), 5-hydroxymethyl cytosine, xanthine, hypoxanthine, 2-aminoadenine, 6- methyl and other alkyl derivatives of adenine and guanine, 2-propyl and other alkyl derivatives of adenine and guanine, 2-thiouracil, 2-thiothymine and 2-thiocytosine, 5- halouracil and cytosine, 5-propynyl uracil and cytosine, 6-aza uracil, cytosine and thymine, 5-uracil (pseudouracil), 4-thiouracil, 8-halo, 8-amino, 8-thiol, 8-thioalkyT, 8- hydroxyl and other 8-substituted adenines and guanines, 5-halo particularly 5-bromo, 5-trifluoromethyl and other 5-substituted uracils and cytosines, 7-methylguanine and 7-methyladenine, 8-azaguanine and 8-azaadenine, 7-deazaguanine and 7-deazaadenine and 3-deazaguanine and 3-deazaadenine. Further nucleobases include those disclosed in United States Patent No. 3,687, 808, those disclosed in the Concise Encyclopedia Of Polymer Science And Engineering, pages 858-859, Kroschwitz, J. I., ed. John Wiley & Sons, 1990, those disclosed by Englisch et al., Angewandte Cheffaie, Iyaternational Edition, 1991,30, 613, and those disclosed by Sanghvi, Y. S. , Chapter 15, Antisense<BR> Research and Applications, pages 289-302, Crooke, S. T. and Lebleu, B. , ed. , CRC Press, 1993.

[0028] Certain heterocyclic base moieties are particularly useful for increasing the binding affinity of the oligomeric compounds that incorporate them to compb- mentary targets. These include 5-substituted pyrimidines, 6-azapyrimidines and N2, N-6 and 0-6 substituted purines, including 2-aminopropyladenine, 5-propynyluracil and 5-propynylcytosine. 5-methylcytosine substitutions have been shown to increase nucleic acid duplex stability by 0.6-1. 2°C (Id., pages 276-278) and are presently pre- ferred base substitutions, even more particularly when combined with selected 2'- sugar modifications such as 2'-methoxyethyl groups.

[0029] Representative United States patents that teach the preparation of het- erocyclic base moieties (modified nucleobases) include, but are not limited to, U. S.

Patents 3,687, 808 ; 4,845, 205; 5,130, 302; 5, 134, 066 ; 5,175, 273; 5,367, 066; 5,432, 272; 5,457, 187; 5,459, 255; 5,484, 908 ; 5,502, 177; 5, 525, 711 ; 5,552, 540; 5,587, 469; 5,594, 121,5, 596,091 ; 5, 614, 617 ; and 5,681, 941, certain of which are commonly owned, and each of which is herein incorporated by reference, and commonly owned United States patent application 08/762, 587, filed on December 10,1996, also herein incorporated by reference.

[0030] A representative list of sugar substituent groups amenable to the pre- sent invention include C,-Czo alkyl, C2-C2o alkenyl, Ci CZO alkynyl, C5-C20 aryl, O- alkyl, 0-alkenyl, O-alkynyl, O-alkylamino, O-alkylalkoxy, 0-alkylaminoalkyl, O- alkyl imidazole, S-alkenyl, S-alkynyl, NH-alkyl, NH-alkenyl, NH-alkynyl, N-dialkyl, 0-aryl, S-aryl, NH-aryl, 0-aralkyl, S-aralkyl, NH-aralkyl, N-phthalimido, halogen (particularly fluoro), keto, carboxyl, nitro, nitroso, nitrile, trifluoromethyl, trifluoro- methoxy, imidazole, azido, hydrazino, hydroxylamino, isocyanato, sulfoxide, sulfone, sulfide, disulfide, silyl, heterocycle, carbocycle, polyamine, polyamide, polyalkylene glycol, and polyethers of the formula (O-alkyl)""where m is 1 to about 10. Preferred among these polyethers are linear and cyclic polyethylene glycols (PEGs), and (PEG)- containing groups, such as crown ethers and those which are disclosed by Ouchiet al.

(D Design and Discovery 1992, 9, 93), Ravasio et al. (J. Org. Chefsa. 1991, 56, 4329) and Delgardo et. au. (Critical Reviews in Therapeutic Drug Carrier Systems 1992, 9, 249), each of which is herein incorporated by reference in its entirety. Fur- ther sugar modifications are disclosed in Cook, P. D., Anti-Cancer Drug Design, 1991, 6, 585-607. Fluoro, 0-alkyl, 0-alkylamino, 0-alkyl imidazole, 0-alkylaminoalkyl, and alkyl amino substitution is described in United States Patent Application serial number 08/398,901, filed March 6,1995, entitled Oligomeric Compounds having Pyrimidine Nucleotide (s) with 2'and 5'Substitutions, hereby incorporated by refer- ence in its entirety.

10031] Additional sugar substituent groups amenable to the present invention include-SR and-NR2 groups, wherein each R is, independently, hydrogen, a protect- ing group or substituted or unsubstituted alkyl, alkenyl, or alkynyl. 2'-SR nucleosides are disclosed in United States Patent No. 5,670, 633, issued September 23,1997, hereby incorporated by reference in its entirety. The incorporation of 2'-SR monomer synthons are disclosed by Hamm et al., J. Org Chen7., 1997, 62, 3415-3420. 2'-NR2 nucleosides are disclosed by Goettingen, M, J Org. Cltein., 1996, 61, 73-6281; and Polushin et al., Setrahedron Lett., 1996, 37, 3227-3230.

[0032] Further sugar substituent groups have one of formula IV or V: wherein: Zo is O, S or NH; J is a single bond, O or C (=O) ; E is Cl-Cto alkyl, N (R,) (R2), N (R,) (Rs), N=C (RI) (R2), N=C (RI) (R5) or has one of for- mula VI or VII; wherein each R6, R7, Rg, Rg and R, o is, independently, hydrogen, C (O) R", substituted or unsubstituted C,-C, o alkyl, substituted or unsubstituted C2-Clo alkenyl, substituted or unsubstituted CZ Clo alkynyl, alkylsulfonyl, arylsulfonyl, a chemical functional group or a conjugate group, wherein the sugar substituent groups are selected from hydroxyl, amino, alkoxy, carboxy, benzyl, phenyl, nitro, thiol, thioalkoxy, halogen, alkyl, aryl, alkenyl and alkynyl; or optionally, R7 and R8, together form a phthalimido moiety with the nitrogen atom to which they are attached; or optionally, Rg and RIO, together form a phthalimido moiety with the nitro- gen atom to which they are attached; each Rll is, independently, substituted or unsubstituted C Clo alkyl, trifluoro- methyl, cyanoethyloxy, methoxy, ethoxy, t-butoxy, allyloxy, 9-fluorenylmethoxy, 2- <BR> <BR> (trimethylsilyl) -ethoxy, 2,2, 2-trichloroethoxy, benzyloxy, butyryl, iso-butyryl, phenyl or aryl; Rs is T-L, T is a bond or a linking moiety ; L is a chemical functional group, a conjugate group or a solid support material ; each Rl and R. is, independently, H, a nitrogen protecting group, substituted or unsubstituted Cl-Cl0 alkyl, substituted or unsubstituted C2-Cl0 alkenyl, substituted or unsubstituted C-Cl0 alkynyl, wherein said substitution is OR3 SR3, Nu3*, N (R3) (R4), guanidino or acyl where said acyl is an acid amide or an ester; or Rl and R2, together, are a nitrogen protecting group or are joined in a ring structure that optionally includes an additional heteroatom selected from N and O ; or Rl, T and L, together, are a chemical functional group; each R3 and R4 is, independently, H, Cl-Clo alkyl, a nitrogen protecting group, or R3 and R4, together, are a nitrogen protecting group; or R3 and R4 are joined in a ring structure that optionally includes an additional heteroatom selected from N and O ; Z4 is OX, SX, or N (X) 2, each X is, independently, H, Cl-C8 alkyl, Cl-C8 haloalkyl, C (=NH) N (H) R. 5, C (=O) N (H) R5 or OC (=O) N (H) R5 ; R5isHorCI-C8alkyl ; Zl, Z2 and Z3 comprise a ring system having from about 4 to about 7 carbon atoms or having from about 3 to about 6 carbon atoms and 1 or 2 hetero atoms wherein said hetero atoms are selected from oxygen, nitrogen and sulfur and wherein said ring system is aliphatic, unsaturated aliphatic, aromatic, or saturated or unsatu- rated heterocyclic; Z5 is alkyl or haloalkyl having 1 to about 10 carbon atoms, alkenyl having 2 to about 10 carbon atoms, alkynyl having 2 to about 10 carbon atoms, aryl having 6 to about 14 carbon atoms, N (R,) (R2) OR,, halo, SRl or CN; each ql is, independently, an integer from 1 to 10; each q2 is, independently, 0 or 1 ; q3 is 0 or an integer from 1 to 10; q4 is an integer from 1 to 10; q5 is from 0,1 or 2; and provided that when q3 is 0, q4 is greater than 1.

[0033] Representative sugar substituent groups of Formula IV are disclosed in United States Patent Application Serial No. 09/130,973, filed August 7,1998, entitled "Capped 2'-Oxyethoxy Oligonucleotides,"hereby incorporated by reference in its en- tirety.

[0034] Representative cyclic sugar substituent groups of Formula V are dis- closed in United States Patent Application Serial No. 09/123,108, filed July 27, 1998, entitled"RNA Targeted 2'-Modified Oligonucleotides that are Conformationally Pre- organized, "hereby incorporated by reference in its entirety.

[0035] Particularly preferred sugar substituent groups include O[(CH2)nO]mCH3, O(CH2)nOCH3, O(CH2)nNH2, O(CH2)nCH3, O(CH2)nONH2, O (CH2) nON [(CH2) nCH3) 32 (where n and m are from 1 to about 10), Cl to Clo lower al- kyl, substituted lower alkyl, alkaryl, aralkyl, 0-alkaryl or 0-aralkyl, SH, SCH3, OCN, Cl, Br, CN, CF3, OCF3, SOCH3, SO2CH3 ONO2 NO2 N3 NH2 heterocycloalkyl, het- erocycloalkaryl, aminoalkylamino, polyalkylamino and substituted silyl. Another particularly preferred modification includes 2'-methoxyethoxy (2'-O-CH2CH2OCH3 or 2'-MOE, Martin et al., Helv. Claim. Acta, 1995, 78, 486). A further preferred sugar substituent group is 2'-dimethylaminooxyethoxy, i. e. , a O (CH2) 2ON (CH3) group, also known as 2'-DMAOE. Representative aminooxy sugar substituent groups are de- scribed in co-owned United States Patent Application serial number 09/344,260, filed June 25,1999, entitled"Aminooxy-Functionalized Oligomers" ; and United States Patent Application serial number 09/370,541, filed August 9,1999, also identified by attorney docket number ISIS-3993, entitled Aminooxy-Functionalized Oligomers and Methods for Making Same; hereby incorporated by reference in their entirety.

[0036] Other preferred modifications include 2'-methoxy (2'-O-CH3), 2'- aminopropoxy (2'-OCH2CH2CH2NH2) and 2'-fluoro (2'-F). The configuration of the sugar substituent group is also variable such as at the 2'-position. In addition to the ribose configuration, the arabinose configuration is also amenable to the present in- vention. Arabinose modifications are known to those skilled in the art and include more recent procedures described in for example, Damha et. al. , J. A. C. S., 1998, 120, 12976-12977; Biocozzjugate Chem., 1999, 10, 299-305; Nucleic Acids Res. (2000), 28 (18), 3625-3635; Biochemistry (2000), 39 (24), 7050-7062.

[0037] Similar modifications may also be made at other positions on nucleo- sides and oligomers, particularly the 3'position of the sugar on the 3'terminal nucleo- side or at a 3'-position of a nucleoside that has a linkage from the 2'position such as a 2'-5'linked oligomer and at the 5'-position at a 5'-terminus. Oligomers may also have sugar mimetics such as cyclobutyl moieties in place of the pentofuranosyl sugar. Rep- resentative United States patents that teach the preparation of such modified sugars structures include, but are not limited to, U. S. Patents 4,981, 957; 5,118, 800; 5,319, 080; 5,359, 044; 5,393, 878; 5,446, 137; 5,466, 786; 5,514, 785; 5,519, 134; 5,567, 811; 5,576, 427; 5,591, 722; 5,597, 909; 5,610, 300; 5,627, 0531 5,639, 873 ; 5,646, 265; 5,658, 873 ; 5,670, 633; and 5,700, 920, certain of which are commonly owned, and each of which is herein incorporated by reference, and commonly owned United States patent 5,859, 221, also herein incorporated by reference.

[0038] Representative guanidino sugar substituent groups that are shown in formula VI and VII are disclosed in co-owned United States Patent Application 09/349,040, entitled"Functionalized Oligomers", filed July 7,1999, hereby incorpo- rated by reference in its entirety.

[0039] Representative acetamido sugar substituent groups are disclosed in United States Patent Application 09/378, 568, entitled"2'-O-Acetamido Modified Monomers and Oligomers", filed August 19,1999, also identified by attorney docket number ISIS-4071, hereby incorporated by reference in its entirety.

[0040] Representative dimethylaminoethyloxyethyl sugar substituent groups are disclosed in International Patent Application PCT/US99/17895, entitled"2'-0- Dimethylaminoethyloxyethyl-Modified Oligonucleotides", filed August 6,1999, also identified by attorney docket number ISIS-4045, hereby incorporated by reference in its entirety.

[0041] As used herein, a"bifunctional linkingmoiety"refers to a hydrocarbyl chain which connects the monomers and oligomers of the invention to a support rm- dium. A preferred linking moiety is a succinyl group. Other linking moieties include, but are not limited to, substituted or unsubstituted C,-C, 0 alkyl, substituted or unsub- stituted C2-C, 0 alkenyl or substituted or unsubstitutedC2-C,, alkynyl, wherein the sub- stituent groups are selected from hydroxyl, amino, alkoxy, carboxy, benzyl, phenyl, nitro, thiol, thioalkoxy, halogen, alkyl, aryl, alkenyl and alkynyl. Other linking mob- ties are known in the art and are equally amenable to the present invention.

[0042] In one embodiment of the present invention modified triphosphate nu- cleotides are prepared with the nucleoside portion linked to a support media. Pre- ferred attachments are via the 2'or 3'-position of the sugar portion of the nucleoside but other points of attachment such as via the heterocyclic base moiety are know in the art and are amenable to the present invention.

[0043] Preferred support media is insoluble and allows all of the reactants to be easily removed by washing with an appropriate solvent. However, soluble or vari- able soluble support media is also known in the art. Such support permits variable solubility of the nucleoside bound synthon in different solvents thereby allowing vari- able solubility. Traditional solid supports are insoluble and are routinely placed in a reaction vessel while reagents and solvents react and or wash the growing chain until cleavage frees the final oligomer. More recent approaches have introduced soluble supports including soluble polymer supports to allow precipitating and dissolving of the synthon at desired points in the synthesis (Gravert et al., Chem. Rev., 1997, 97, 489-510).

[0044] Representative support media that are amenable to the methods of the present invention include without limitation : controlled pore glass (CPG); oxalyl- controlled pore glass (see, e. g., Alul, et al., Nucleic Acids Research 1991, 19, 1527); TENTAGEL Support, (see, e. g., Wright, et al., Tetrahedron Letters 1993, 34, 3373); or POROS, a copolymer of polystyrene/divinylbenzene available from Perceptive Biosystems. The use of a soluble support media, poly (ethylene glycol), with mmlecu- lar weights between 5 and 20 kDa, for large-scale synthesis of oligonucleotides is de- scribed in, Bonora et al., Organic Process Research & Devdopment, 2000, 4, 225- 231.

[0045] Many hydroxyl protecting groups known in the art are amenable to use in the present invention. Examples of certain preferred hydroxyl protecting groups include, but are not limited to, t-butyl, t-butoxymethyl, methoxymethyl, tetrahydro- pyranyl, 1-ethoxyethyl, 1- (2-chloroethoxy) ethyl, 2-trimethylsilylethyl, p- chlorophenyl, 2,4-dinitrophenyl, benzyl, 2, 6-dichlorobenzyl, diphenylmethyl, p, p=- dinitrobenzhydryl, p-nitrobenzyl, triphenylmethyl, trimethylsilyl, triethylsilyl, t- butyldimethylsilyl, t-butyldiphenylsilyl, triphenylsilyl, benzoylformate, acetate, chloroacetate, trichloroacetate, trifluoroacetate, pivaloate, benzoate, p- phenylbenzoate, 9-fluorenylmethyl carbonate, mesylate and tosylate.

[0046] A further list of hydroxyl protecting groups amenable to the present invention may be represented by the group having the formula :-C (R,) (R2) (R3) wherein each of R,, R2 and R3 is an unsubstituted or mono-substituted aryl or het- eroaryl group selected from phenyl, naphthyl, anthracyl, and five or six membered heterocylic rings with a single heteroatom selected from N, O and S, or two N het- eroatoms, including quinolyl, furyl, and thienyl; where the substituent is selected from <BR> <BR> halo (i. e. , F, Cl, Br, and I), nitro, Cl-C4-alkyl or alkoxy, and aryl, aralkyl and cycloal- kyl containing up to 10 carbon atoms; and wherein R2 and R3 may each also be C fC4 alkyl or aralkyl or cycloalkyl containing up to 10 carbon atoms.

[0047] In one embodiment of the present invention there is a processes for preparing nucleoside triphosphate compounds of formula I: wherein: Y, is Se and Y, is OH or SH; or Y, is O and Y, is NHR, or BH3 ; or Y, is S and Y2 is NHR"SH or BH3 ; Y3 is OH; NHRI ; alkyl or alkoxy; RI is hydrogen, substituted or unsubstituted Cl-Cl2 alkyl, substituted or unsub- stituted C2-CI2 alkenyl, substituted or unsubstituted CfCI2 alkynyl, substituted or un- substituted CS to C7 cyclic alkyl, substituted or unsubstituted C5-C20 alkyaryl, substi- tuted or unsubstituted heterocyclyl, or a nitrogen protecting group, wherein said sub- stituent is substituted or unsubstituted CfC20 aryl, 0-alkyl, O-alkylalkoxy, 0- alkylaminoalkyl, 0-alkyl imidazole, S-alkyl, NH-alkyl, N-dialkyl, aryl, heterocycle, substituted heterocycle, O-aryl, S-aryl, NH-aryl, 0-aralkyl, S-aralkyl, or N-aralkyl ; one of X, and X2 is H, hydroxyl, a protected hydroxyl, or a sugar substituent group and the other of X, and X2 is-O-J-SM ; Bx is an optionally protected heterocyclic base moiety; one of X, and X2 is H, hydroxyl, a protected hydroxyl, or a sugar substituent group and the other of XI and X2 is hydroxyl, a protected hydroxyl or-O-J-SM ; J is a bifunctional linking moiety; and SM is a support medium; comprising the steps of : a) providing a nucleosidyl-5'-cyclotriphosphite having the formula II: wherein: one of XZ and X, is H, hydroxyl, a protected hydroxyl, or a sugar sub- stituent group and the other of X2 and Xl is-O-SSM ; b) reacting said nucleosidyl-5'-cyclotriphosphite with an oxidizing reagent for a time and under conditions effective to give an oxidized compound hav- ing the formula III: wherein: Z is Se, S, BH3, or NHR, ; and e) treating said oxidized compound with a ring opening reagent to give compound I.

[0048] Another embodiment includes a process wherein the oxidizing agent is a mixture of I2 and NH3 in a suitable solvent. In other embodiments, the oxidizing agent is a mixture of I2 and NH2RI in a suitable solvent. In general embodiments, the oxidizing agent is a solution of sulfur in a mixture of suitable solvents. In more gel- eral embodiments the oxidizing agent is a borane-N, N-diisopropylethyl complex.

[0049] Suitable solvents useful in connection with this invention can be 1,4- dioxane, THF, (Me0) 3PO, acetonitrile, DMF, and formamide. In many forms, the solvent is 1,4-dioxane, whereas other embodiments have THF as the suitable solvent.

Mixtures of carbon disulfide, pyridine, and tryiethylamine can also be used in some embodiments.

[0050] This invention can be conducted wherein said oxidizing agent is a solu- tion of 3H-1, 2-benzothiaselenol-3-one dissolved in a suitable solvent. Other em- bodiments have solvents that comprise acetonitrile. The solvent used can also be a mixture of acetonitrile and triethylamine. Such mixture comprises from about 1% to about 30% triethyl amine in acetonitrile by volume. The oxidation step can be con- ducted for up to about 3 hours or up to about 2 hours. In other embodiments, the step can be conducted for up to about 40 minutes.

[0051] Oxidized cyclic intermediates of the present invention may be opened up in a number of ways. In some embodiments, the cyclic intermediates may be opened using a solution of Li2S and 18-crown-6ether in dimethyl-formamide. In other embodiments, the ring may be opened by hydrolysis or action of different amines. In general embodiments, the cyclic intermediates can be hydrolized with water.

[0052] The processes of the present invention can be augmented to include treating the nucleoside triphosphate compound with a cleaving reagent to cleave said compound from the support medium. In some embodiments the treatment with said cleaving reagent removes protecting groups present on the heterocyclic base moiety.

Protecting groups can also be removed by treating the compound with a deprotecting reagent in other embodiments.

[0053] Certain embodiments of the invention may exist in wherein Y, is Se and Y2 is OH, Y, is O and YZ is NHR, wherein said R, is other than H, Y, is O and Y2 is NHRI, Y, is O and Y2 is BH3 and Yl is S and Y2 is SH.

[0054] Many forms of the inventions exist as a nucleosidy5'- cyclotriphosphite compound having the formula II: wherein: Bx is an optionally protected heterocyclic base moiety; one of XI and X2 is H, hydroxyl, a protected hydroxyl, or a sugar sub- stituent group and the other of X, and X2 is-O-J-SM ; J is a bifunctional linking moiety; and SM is a support medium.

[0055] Other forms of the invention are compounds having the formula III: wherein: Z is Se, S, BH3, or NHRI ; Bx is an optionally protected heterocyclic base moiety; one of Xl and Y., is H, hydroxyl, a protected hydroxyl, or a sugar sub- stituent group and the other of Xl and X2 is-O-J-SM ; J is a bifunctional linking moiety; and SM is a support medium.

Experimental [0056] The phosphitylating reagent 2-chloro-4H-1, 3,2-benzodioxaphosphorin- 4-one was purchased from Aldrich and used as 1M solution in dioxane (always pre- pared fresh prior to use). The solvents dioxane, pyridine, acetontirile, N, N-dimethyl- formamide and tetrahydrofuran were purchased from Aldrich as anhydrous and used without further purification unless otherwise stated. Solvents were stored over m- lecular sieves 4A. Tri-n-butylamine, n-butylamine, n-propylamine and methylamine (2 M solutions in THF) were dried and stored over 4Amolecular sieves.

[0057] The bis (tri-n-butylammonium) pyrophosphate was obtained from Fluka and stored as a 0. 5M solution in DMF over 4A molecular sieves.

[0058] TLC was performed on HPTLC Fertigplatten Si 5000F (Merck Dann- stad) and detected by visualization under short wave UV light or by heating the plate at 110 °C after spraying with 5% solution of sulfuric acid in ethanol.

[0059] 3'P NMR spectra were recorded on a Varian spectrometer operating at 400 MHz with broad band decoupling. Spectra of intermediates synthesized in solu- tion were recorded after addition of anhydrous deuterated chloroform (CDC13). Re- versed phase HPLC was achieved with a Gilson (Middleton, WI) quaternary pump system, consisting of 4 pumps, with dual wavelength detector. Components of the HPLC system were controlled by a Gilson's Uniport software package. A Phenone- <BR> <BR> nex (Torrance, CA) Luna (C-18 (2) ), 250 X 21.2 mm, 5-um particle size, column and a linear gradient from 1% to 25 % of methanol in 60 minutes at constant pH 7, concen- tration TEAA (50 mM) was used to purify the synthesized nucleoside triphosphates.

The flow rate was 10 mL/min.

[0060] The mass spectra of the purified triphosphates was determined using on-line HPLC mass spectrometry on a Hewlett-Packard (Palo Alto, CA) MSD 1100.

[0061] RP HPLC was performed on a Phenomenex Luna (C-18 (2) ), 150 x 2 mm, plus 30 x 2 mm guard column, cm particle size. A 0 to 50% linear gradient of acetonitrile in 20 mM TEAA (pH 7) was performed in series with mass spectra detec- tion in the negative ionization mode. Nitrogen gas and a pneumatic nebulizer were used to generate the electrospray. The mass range of 150-900 was sampled. Molecu- lar masses were determined using the HP Chemstation analysis package.

EXAMPLES Example 1 Attachment of nucleosides to solid support [0062] Nucleosides were protected if necessary and attached to support media using standard procedures. A fully protected nucleoside is selected having a free hy- droxyl group at the 2'or 3'-position. A typical selection is a 5'-DMT-nucleoside hav- ing any exocyclic amino groups protected as the N-acyl group. The free hydroxyl group is attached to an amino functionalized solid support (e. g. CPG or polystyrene using a succinate linking group). A general procedure is illustrated in by Sproat et al., Oligonucleotides and Analogues, Ed. , IRL Press, Oxford. 1991; pp. 49-86 ; Eckstein, F. Ed.

Example 2 General procedure for the synthesis of solid support bound cyclic triphosphite (4) Scheme 1 [0063] Solid support derivatized with a selected nucleoside (as per Example 1, 100 ßmoles) was placed in a small glass column fitted with a septum and equipped with a glass sinter and tap at the bottom (volume about 16 mL). The support was treated with a 3% solution of trichloroacetic acid in dichloromethane (2 x 10 mL) for 2 minutes to remove the 5'-protecting group. The solid support was washed with di- chloromethane (10 mL), dry acetonitrile (10 mL), a dry mixture of pyridine and diox- ane (10 mL, 1: 3, v/v). A fresh 1M solution of 2-chloro-4H-1. 3.2- benzodioxaphosphorin-4-one in dry dioxane (4 mL) was then added to the support suspended in dry pyridine/dioxane (8 mL, 1: 3, v/v). The reactor was gently agitated for 20 minutes, the phosphitylating solution removed under an atmosphere of argon and the support washed with a dry mixture of pyridine and dioxane (10 mL, 1: 3, v/v) followed by acetonitrile (10 mL) and N, N-dimethylformamide (10 mL). A mixture of 0.4M bis (tributylammonium) pyrophosphate in dry DMF (6 mL) and tri-n-butylamine (2 mL) was added to the reactor with agitation for 40 minutes. The support was washed with dry N, N-dimethylformamide (10 mL), dry acetonitrile (10 mL) and dry tetrahydrofuran (10 mL) to give the support bound cyclic triphosphate nucleoside (4, Scheme 1). Example 3 General procedure for the synthesis or a-amino triphosphate nucleosides Scheme 2 [0064] The cyclic triphosphite (4, Example 2) was oxidized using iodine and a primary amine such as an alkylamine. The selected primary amine (4 mL) was sus- pended in a solution of iodine in tetrahydrofuran (224 mg in 5 mL). The solid support was treated with the oxidation mixture containing the primary amine and agitated for 40 minutes at 25°C. Excess oxidation mixture was removed by extensive washing with dry tetrahydrofuran (10 mL) and dry acetonitrile (10 mL). Oxidized intermediate (5) was hydrolized with water (5 mL at 25°C for 90 minutes). The a-amino modified nucleoside triphosphate was cleaved and deprotected by treating the solid support with 25% aqueous ammonia in a sealed glass vial (15 hours at 25C and 2 hours at 55°C).

[0065] The cooled ammonia solution of crude a-amino modified nucleoside triphosphate was evaporated to dryness. The residue was dissolved in a 0.2M solution of triethylammonium bicarbonate buffer (pH=7) and purified by reverse phase and ion exchange HPLC to give the a-amino triphosphate nucleoside (6).

Analytic data for selected a-amino modified nucleoside triphosphates 2'-O-Methyl guanosine 5'- (a-P- (N-methyl) triphosphate [0066]"C NMR (D20) : (isomer I Sp) 8 = 159.13 (C-6); 154.21 (C-2); 151.92 (C-4); 138.25 (C-8) ; 116.26 (C-5); 85.4 (C-1') ; 84. 46 (C-4'); 82.54 (C-2'); 69.2 (C- 3') ; 65.51 (C-5'); and 58.3 (OCH3).

[0067]'3C NMR(D2O): (isomer II Rp) 8 = 159.09 (C-6); 154.23 (C-2); 151.91 (C-4) ; 138. 05 (C-8); 116.21 (C-5); 85.5 (C-1') ; 84.46 (C-4'); 82.6 (C-2') ; 69. 18 (C- 3'); 65.82 (C-5'); and 58.3 (OCH3).

[0068]"P NMR (D20):# = + 33.71 (d,1P,α-P, isomer I (Sp) ), + 33.58 (d, 1P,<BR> a-P, isomer II (Rp) ), -10. 94 (d, lP, ^y, P), -24.69 (dd, 1P, ß-P) [0069] Molecular weights for Rp and Sp stereoisomers were determined by LC-HPLC mass spectrometry (Hewlett-Packard MSD 1100) using a Luna (C-18 (2)) column, 150 x 2 mm, 3-pm particle size and 0-50% gradient of MeCN in 20 mM TEAA (pH 7). The mass spectra detection was perfomed in the negative ionization mode. Molecular masses were determined using the HP Chemstation analysis package and were equal: 599.9 (isomer I) and 599.9 (isomer II). Calculated MW=600. 17.

2'-0-Methyl guanine 5'- (a-P- (N-butyl) triphosphate [0070] 13C NMR (D2O): 8 = 166.74 (C-6); 151.9 (C-2); 137. 62 (C-5); 111.94 (C-4); 85.63 (C-1') + 85.05 (C-2'); 70.94 (C-3') ; 65.49 (C-5'); 59.15 (OMe); 38.85 (C- 2'); 41.66 (C-NH) ; 33.26 (C2-NH) ; 19.67 (C3-NH) ; 13.37 (C4-NH) ; and 12.5 (C5- CH3).

[0071] 31P NMR (D20) : 8 =-0.39 (d, 1P, a-P),-11. 41 (d, 1P, y, P), and- 22.64 (dd, 1P, P-P).

2'-Deoxythymidine 5'- (a-P- (amino) triphosphate [0072]"C NMR (DO) : 8 = 166.9 (C-6); 152.1 (C-2); 137.74 (C-5); 112.12 (C-4); 85.82 + 85.73 (C-1'+ C-2'); 71.3 (C-3') ; 65.7 (C-5'); 59.15 (OMe); 38. 85 (C- 2'); and 12.5 (C,-CH,).

[0073] 3'P NMR (D20) : # = 0.11 (d, 1P, a-P),-10. 84 (d, IP, y, P), and-22.6 (dd, 1P,-P).

[0074] The following a-amino triphosphate nucleosides having Formula 6 were prepared following the procedure illustrated above: Yl Bx Xi - CH3 G'B°, CBZ or T H or-OMe<BR> -CH2CH2CH3 GiBU, CBZ or T H or-OMe<BR> -CH2CH2CH2CH3 GiBU, CBZ or T H or-OMe<BR> -H GiBU, CBZ or T H or-OMe<BR> Yl = OH, Y3 = OH, and Xz = OH.

Example 4 General procedure for the synthesis or a-seleno triphosphate nucleosides [0075] Solid support bound cyclic triphosphite nucleoside (4, Scheme 1) was prepared as illustrated in Example 2 above. The oxidation of the cyclic triphosphite nucleoside was carried out using a 0.2 M solution of 3H, 1, 2-benzothiaselenol-3-one in acetonitrile (8 mL) for 3 hours, followed by washing with acetonitrile (3 x 15 mL).

The oxidized material was hydrolyzed with a mixture of water and acetonitrile (9/1, v/v, 8 mL) for 90 minutes, followed by washing with acetonitrile, methanol and di- chloromethane (15 mL of each). The longer hydrolysis time proved to be necessary as the a-seleno compound was less reactive compared with the a-Sulfur analogue (a-S- analogue was hydrolyzed completely in 30 minutes). The solid support was dried us- ing a stream of dry nitrogen and removed from the reactor. The product was cleaved from the solid support using concentrated ammonia in a closed glass vial (for 12 hours at 25°C and 3 hours at 55°C). The a-Se-nucleoside triphosphate was obtained as es- sentially equal amounds of Rp and Sp stereoisomers. These stereoisomers were se- rated using ion-exchange and reverse-phase HPLC. The ion-exchange HPLC purifi- cation was preformed using MonoQ column (Pharmacia), 100 X 30 mm, and the fol- lowing gradient: 0-0.72M NaCl at constant Tris (20 mM, pH 7), flow rate 6.5 mL/min. Rt for the stereoisomers was 17.7 minutes. The RP-HPLC separations were performed using a Luna (C-18 (2) ) column, 250 X 21.2 mm (Phenomenex, CA), 5-Rm particle size column using linear gradient of MeOH (1%-25 %) in 60 minutes, at con- stant TEAA (pH 7,50 mM), flow rate 10 mL/minutes. Theretention times were 45.6 and 50 minutes for the Sp and Rp isomers respectively.

[0076l 13C NMR (DO) : (isomer I Sp) 8 = 159.13 (C-6); 154.21 (C-2) ; 151. 92 (C-4); 138.25 (C-8); 116.26 (C-5); 85.4 (C-1') ; 84.46 (C-4'); 82.54 (C-2'); 69.2 (C- 3'); 65.51 (C-5'); 58.3 (OCH3) ; (isomer 11) 8= 159.09 (C-6); 154.23 (C-2); 151.91 (C- 4); 138. 05 (C-8); 116.21 (C-5); 85.5 (C-1') ; 84. 46 (C-4'); 82. 6 (C-2') ; 69.18 (C-3'); 65.82 (C-5'); and 58.3 (OCH3). <BR> <BR> <P>[0077] 31p NMR (Dz0) : 8 = + 33.71 (d, 1P, a-P, isomer I (Sp) ), + 33.58 (d, 1P,<BR> a-P, isomer II (Rp) ), -10. 94 (d, IP, y, P), and-24.69 (dd, 1P, ß-P).

[0078] Molecular weight (MW) for Rp and Sp stereoisomers were determined using LC-HPLC mass spectrometry (Hewlett-Packard MSD 1100) using Luna (C- <BR> <BR> 18 (2) ) column, 150 x 2 mm, 3-jam particle size and 0-50% gradient of MeCN in 20 mM TEAA (pH 7). The mass spectra detection was perfomed in the negative ioniza- tion mode. Molecular masses were determined using the HP Chemstation analysis package and were equal: 599.9 (isomer I) and 599.9 (isomer II). Calculated MW=600.17.

Example 5 General procedure for the synthesis or oc-borano triphosphate nucleosides [0079] Solid support bound cyclic triphosphite nucleoside (4, Scheme 1) was prepared as illustrated in Example 2 above. The oxidation of the cyclic triphosphit nucleoside was carried out using borane-N, N-diisopropylethylamine complex. The reaction mixture was agitated for 180 minutes at 25°C and the oxidation reagent was removed by repeated washing with dry acetonitrile (20 mL) and DMF (10 mL). The oxidized intermediate was hydrolized with water (5 mL at 25°C for 90 minutes). The a-borano modified nucleoside triphosphate was cleaved and deprotected by treating the solid support with 25% aqueous ammonia in a sealed glass vial (15 hours at 25°C and 2 hours at 55°C). The cooled ammonia solution of crude a-amino modified nu- cleoside triphosphate was evaporated to dryness. The residue was dissolved in a 0.2M solution of triethylammonium bicarbonate buffer (pH=7) and purified by reverse phase and ion exchange HPLC to give the a-amino triphosphate nucleoside (6).

Example 6 General procedure for the synthesis or a-borano-a-thio-triphosphate nucleosides [0080] Solid support bound cyclic triphosphite nucleoside (4, Scheme 1) was prepared as illustrated in Example 2 above. The cyclic triphosphite nucleoside was oxidized with borane-N, N-diisopropylethylamine complex. The reaction mixture was agitated for 180 minutes at 25°C and excess oxidation reagent was removed by exten- sive washing with dry acetonitrile (20 mL) and DMF (10 mL). The resulting cyclic triphosphate was treated with a solution of Li2S in dimethyl-formamide in the pres- ence of crown ether (18-crown-6) (8 mL at 25°C for 120 minutes) to give the solid support bound triphosphate. The solid support was treated with 25% aqueous ammo- nia in a sealed glass vial (15 hours at 25°C and 2 hrs at 55aC). The resulting ammonia solution of a-borano-a-thiotriphosphate nucleoside was evaporated to dryness. The residue was dissolved in a 0.2M solution of triethylammonium bicarbonate buffer (pH=7) and purified by reverse phase and ion exchange HPLC.

Example 7 General procedure for the synthesis or a-dithiotriphosphate nucleosides [0081] Solid support bound cyclic triphosphite nucleoside (4, Scheme 1) was prepared as illustrated in Example 2 above. The cyclic triphosphite nucleoside was oxidized with a 5% solution of elemental sulfur in carbon disulfide, pyridine and tri- etylamine (95/95/5, v/v/v) with agitation for 120 minutes at 25°C. The solid support was repeatedly washed with dry acetonitrile (20 mL). The resulting cyclic triphos- phate nucleoside was treated with a 0. 2M solution of LiS and 18-crown-6 ether in dimethyl-formamide (8 mL at 25°C for 120 minutes). The solid support was treated with 25% aqueous ammonia in a sealed glass vial (15 hours at 25°C and 2 hrs at 55°C). The resulting ammonia solution of a-dithiotriphosphate nucleoside was evapo- rated to dryness. The residue was dissolved in a 0.2M solution of triethylanmonium bicarbonate buffer (pH=7) and purified by reverse phase and ion exchange HPLC.

Example 8 General procedure for the synthesis or a-seleno-a-thio triphosphate nucleosides [0082] Solid support bound cyclic triphosphite nucleoside (4, Scheme 1) is prepared as illustrated in Example 2 above. The cyclic triphosphite nucleoside was oxidized with a 0.2M solution of 3H-1, 2benzothiaselenol-3-one in acetonitrile and triethylamine (95/5, v/v). The reaction mixture is agitated for 120 minutes at 25°C.

The support is washed repeatedly with dry acetonitrile (20 mL). The oxidized cyclic intermediate is treated with a 0.2M solution of Li, in dimethylformamide (8 mL) in the presence of a crown ether (18-crown-6,500 mg) at 25°C for 120 minutes). The support is treated with 25% aqueous ammonia in a sealed glass vial (15 hours at 25°C and 2 hrs at 55°C). The resulting ammonia solution ofa-seleno-a-thio triphosphate nucleoside is evaporated to dryness. The residue is dissolved in a 0.2M solution of triethylammonium bicarbonate buffer (pH=7) and purified by reverse phase and ion exchange HPLC.

Example 9 General procedure for the synthesis or a-amino-a-thio triphosphate nucleosides [0083] Solid support bound cyclic triphosphite nucleoside (4, Scheme 1) is prepared as illustrated in Example 2 above. The cyclic triphosphite nucleotide is oxi- dized with iodine in the presence of the corresponding amine in an organic solvent.

Ammonia is used to attach an amino group and a primary amine having a single sub- stituent defined by R, in example 3 above is used to attach a substituted amino group at the oc-position. Reaction is performed by addition of ammonia (0. 5M in dioxane) or a desired primary amine (XX mmoles) (4 mL) to the solid support suspended in iodine solution in an organic solvent such as tetrahydrofuran (224 mg in 5 mL). Next the reaction mixture is agitated for 40 minutes at 25°C. The solid support is repeat- edly washed with dry tetrahydrofuran (10 mL) and dry acetonitrile (10 mL). The solid support is treated with a 0.2M solution of Li2S in dimethylformamide (8 mL) in the presence of a crown ether (18-crown-6,500 mg) at 25°C for 120 minutes. The support is treated with 25% aqueous ammonia in a sealed glass vial (15 hours at 25°C and 2 hrs at 55°C). The resulting ammonia solution of a-alkylamino-a-thio triphos- phate nucleoside is evaporated to dryness. The residue is dissolved in a 0.2M solution of triethylammonium bicarbonate buffer (pH=7) and purified by reverse phase and ion exchange HPLC.

Example 10 General procedure for the synthesis or a-substituted-y-amino triphosphate nu- cleosides Preparation of a-borano-y- (N-propyl) amino triphosphate nucleoside [0084] The oxidized cyclic intermediate of Example x is treated with ammonia or a primary amine (-NHRI) to give the corresponding y-substituted-oc-modified sup- port bound triphosphate nucleoside.

Solid support bound cyclic triphosphite nucleoside (4, Scheme 1) is prepared as illus- trated in Example 2 above. The oxidation of the cyclic triphosphite nucleoside is car- ried out using borane-N, N-diisopropylethylamine complex. The reaction mixture is agitated for 180 minutes at 25°C and the oxidation reagent is removed by repeated washing with dry acetonitrile (20 mL) and DMF (10 mL). The oxidized intermediate is procedure for treatment of the oxidized cyclic triphosphate with an amine to prepare the y-amino derivative.

[0085] The oc-borano modified nucleoside triphosphate is cleaved and depro- tected by treating the solid support with 25% aqueous ammonia in a sealed glass vial (15 hours at 25°C and 2 hours at 55°C). The cooled ammonia solution of crude a- amino modified nucleoside triphosphate is evaporated to dryness. The residue is dis- solved in a 0.2M solution of triethylammonium bicarbonate buffer (pH=7) and puri- fied by reverse phase and ion exchange HPLC to give the a-amino triphosphate nu- cleoside (6).

[0086] As will be recognized additional objects, advantages, and novel fea- tures of this invention will become apparent to those skilled in the art upon examim-. tion of the following examples thereof, which are not intended to be limiting.