CYCLIC NUCLEOTIDE ANALOGS

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application Nos. 61/536,445, filed September 19, 2011; and 61/426,471, filed December 22, 2010; both of which are incorporated herein by reference in their entirety; including any drawings.

BACKGROUND

Field

[0002] The present application relates to the fields of chemistry, biochemistry and medicine. More particularly, disclosed herein are cyclic nucleotide analogs, pharmaceutical compositions that include one or more cyclic nucleotide analogs and methods of synthesizing the same. Also disclosed herein are methods of treating diseases and/or conditions with cyclic nucleotide analogs alone or in combination therapy with other agents.

Description

[0003] Nucleoside analogs are a class of compounds that have been shown to exert antiviral and anticancer activity both in vitro and in vivo, and thus, have been the subject of widespread research for the treatment of viral infections and cancer. Nucleoside analogs are usually therapeutically inactive compounds that are converted by host or viral enzymes to their respective active anti-metabolites, which, in turn, may inhibit polymerases involved in viral or cell proliferation. The activation occurs by a variety of mechanisms, such as the addition of one or more phosphate groups and, or in combination with, other metabolic processes.

SUMMARY

[0004] Some embodiments disclosed herein relate to a compound of Formula (I) or a pharmaceutically acceptable salt thereof.

[0005] Some embodiments disclosed herein relate to methods of ameliorating and/or treating a neoplastic disease that can include administering to a subject suffering from the neoplastic disease a therapeutically effective amount of one or more compounds of Formula (I), or a pharmaceutically acceptable salt thereof, or a pharmaceutical composition that includes one or more compounds of Formula (I), or a pharmaceutically acceptable salt thereof. Other embodiments described herein relate to using one or more compounds of Formula (I), or a pharmaceutically acceptable salt thereof, in the manufacture of a medicament for ameliorating and/or treating a neoplastic disease. Still other embodiments described herein relate to one or more compounds of Formula (I), or a pharmaceutically acceptable salt thereof, or a pharmaceutical composition that includes one or more compounds of Formula (I), or a pharmaceutically acceptable salt thereof, that can be used for ameliorating and/or treating a neoplastic disease.

[0006] Some embodiments disclosed herein relate to methods of inhibiting the growth of a tumor that can include administering to a subject having a tumor a therapeutically effective amount of one or more compounds of Formula (I), or a pharmaceutically acceptable salt thereof, or a pharmaceutical composition that includes one or more compounds of Formula (I), or a pharmaceutically acceptable salt thereof. Other embodiments described herein relate to using one or more compounds of Formula (I), or a pharmaceutically acceptable salt thereof, in the manufacture of a medicament for inhibiting the growth of a tumor. Still other embodiments described herein relate to one or more compounds of Formula (I), or a pharmaceutically acceptable salt thereof, or a pharmaceutical composition that includes one or more compounds of Formula (I), or a pharmaceutically acceptable salt thereof, that can be used for inhibiting the growth of a tumor.

[0007] Some embodiments disclosed herein relate to methods of ameliorating and/or treating a viral infection that can include administering to a subject suffering from the viral infection a therapeutically effective amount of one or more compounds of Formula (I), or a pharmaceutically acceptable salt thereof, or a pharmaceutical composition that includes one or more compounds of Formula (I), or a pharmaceutically acceptable salt thereof. Other embodiments described herein relate to using one or more compounds of Formula (I), or a pharmaceutically acceptable salt thereof, in the manufacture of a medicament for ameliorating and/or treating a viral infection. Still other embodiments described herein relate to one or more compounds of Formula (I), or a pharmaceutically acceptable salt thereof, or a pharmaceutical composition that includes one or more compounds of Formula (I), or a pharmaceutically acceptable salt thereof, that can be used for ameliorating and/or treating a viral infection.

[0008] Some embodiments disclosed herein relate to methods of ameliorating and/or treating a viral infection that can include contacting a cell infected with the virus with an effective amount of one or more compounds described herein, or a pharmaceutically acceptable salt of one or more compounds described herein, or a pharmaceutical composition that includes one or more compounds described herein, or a pharmaceutically acceptable salt thereof. Other embodiments described herein relate to using one or more compounds described herein, or a pharmaceutically acceptable salt of one or more compounds described herein, in the manufacture of a medicament for ameliorating and/or treating a viral infection that can include contacting a cell infected with the virus with an effective amount of said compound(s). Still other embodiments described herein relate to one or more compounds described herein, or a pharmaceutically acceptable salt of one or more compounds described herein, or a pharmaceutical composition that includes one or more compounds described herein, or a pharmaceutically acceptable salt thereof, that can be used for ameliorating and/or treating a viral infection by contacting a cell infected with the virus with an effective amount of said compound(s).

[0009] Some embodiments disclosed herein relate to methods of inhibiting replication of a virus that can include contacting a cell infected with the virus with an effective amount of one or more compounds described herein, or a pharmaceutically acceptable salt of one or more compounds described herein, or a pharmaceutical composition that includes one or more compounds described herein, or a pharmaceutically acceptable salt thereof. Other embodiments described herein relate to using one or more compounds described herein, or a pharmaceutically acceptable salt of one or more compounds described herein, in the manufacture of a medicament for inhibiting replication of a virus that can include contacting a cell infected with the virus with an effective amount of said compound(s). Still other embodiments described herein relate to one or more compounds described herein, or a pharmaceutically acceptable salt of one or more compounds described herein, or a pharmaceutical composition that includes one or more compounds described herein, or a pharmaceutically acceptable salt thereof, that can be used for inhibiting replication of a virus by contacting a cell infected with the virus with an effective amount of said compound(s).

[0010] Some embodiments disclosed herein relate to methods of ameliorating and/or treating a parasitic disease that can include administering to a subject suffering from the parasitic disease a therapeutically effective amount of one or more compounds of Formula (I), or a pharmaceutically acceptable salt thereof, or a pharmaceutical composition that includes one or more compounds of Formula (I), or a pharmaceutically acceptable salt thereof. Other embodiments described herein relate to using one or more compounds of Formula (I), or a pharmaceutically acceptable salt thereof, in the manufacture of a medicament for ameliorating and/or treating a parasitic disease. Still other embodiments described herein relate to one or more compounds of Formula (I), or a pharmaceutically acceptable salt thereof, or a pharmaceutical composition that includes one or more compounds of Formula (I), or a pharmaceutically acceptable salt thereof, that can be used for ameliorating and/or treating a parasitic disease. [0011] Some embodiments disclosed herein relate to methods of ameliorating and/or treating a viral infection that can include administering to a subject suffering from the viral infection a therapeutically effective amount of a compound described herein or a pharmaceutically acceptable salt thereof (for example, one or more compounds of Formula (I), or a pharmaceutically acceptable salt thereof), or a pharmaceutical composition that includes a compound described herein, in combination with an agent selected from an interferon, ribavirin, a HCV protease inhibitor, a HCV polymerase inhibitor, a NS5A inhibitor, an other antiviral compound, a compound of Formula (AA), a mono-, di- and/or tri-phosphate thereof, a compound of Formula (CC), and a compound of Formula (DD), or a pharmaceutically acceptable salt or any of the foregoing. Some embodiments disclosed herein relate to methods of ameliorating and/or treating a viral infection that can include contacting a cell infected with the viral infection with a therapeutically effective amount of a compound described herein or a pharmaceutically acceptable salt thereof (for example, one or more compounds of Formula (I), or a pharmaceutically acceptable salt thereof), or a pharmaceutical composition that includes a compound described herein, in combination with an agent selected from an interferon, ribavirin, a HCV protease inhibitor, a HCV polymerase inhibitor, a NS5A inhibitor, an other antiviral compound, a compound of Formula (AA), a mono-, di- and/or tri-phosphate thereof, a compound of Formula (CC), and a compound of Formula (DD), or a pharmaceutically acceptable salt of any of the foregoing. Some embodiments disclosed herein relate to methods of inhibiting replication of a virus that can include administering to a subject a therapeutically effective amount of a compound described herein or a pharmaceutically acceptable salt thereof (for example, a compound of Formula (I), or a pharmaceutically acceptable salt thereof), or a pharmaceutical composition that includes a compound described herein, or a pharmaceutically acceptable salt thereof, in combination with an agent selected from an interferon, ribavirin, a HCV protease inhibitor, a HCV polymerase inhibitor, a NS5A inhibitor, an other antiviral compound, a compound of Formula (AA), a mono-, di- and/or tri-phosphate thereof, a compound of Formula (CC), and a compound of Formula (DD), or a pharmaceutically acceptable salt of any of the foregoing. In some embodiments, the agent can be a compound, or a pharmaceutically acceptable salt thereof, selected from Compound 1001-1014, 2001-2010, 3001-3008, 4001-4005, 5001-5002, 6000-6078, 7000-7077 or 9000, or a pharmaceutical composition that includes one or more of the aforementioned compounds, or pharmaceutically acceptable salt thereof. In some embodiments, the method can include administering a second agent selected from an interferon, ribavirin, a HCV protease inhibitor, a HCV polymerase inhibitor, a NS5A inhibitor, an other antiviral compound, a compound of Formula (AA), a mono-, di- and/or tri-phosphate thereof, a compound of Formula (CC), and a compound of Formula (DD), or a pharmaceutically acceptable salt of any of the foregoing. In some embodiments, the viral infection can be HCV.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figures 1A-1B show example HCV protease inhibitors.

[0013] Figure 2 shows example nucleoside HCV polymerase inhibitors.

[0014] Figure 3 shows example non-nucleoside HCV polymerase inhibitors.

[0015] Figure 4 shows example NS5A inhibitors.

[0016] Figure 5 shows example other antivirals.

[0017] Figures 6A-6M show example compounds of Formula (CC).

[0018] Figures 7A-70 show example compounds of Formula (AA), triphosphates thereof.

[0019] Figures 8A-8C show example compounds of Formula (I).

[0020] Figure 9 shows Formula (DD).

DETAILED DESCRIPTION

[0021] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as is commonly understood by one of ordinary skill in the art. All patents, applications, published applications and other publications referenced herein are incorporated by reference in their entirety unless stated otherwise. In the event that there are a plurality of definitions for a term herein, those in this section prevail unless stated otherwise.

[0022] As used herein, any "R" group(s) such as, without limitation, R, R ¹ , R ² , R ³ , p ⁴ _R 5 _R 6 _R 7 _R 8 _R 9 _R 10 _R l l _R 12 _R 13 _R 14 _R 15 _R 16 _R 17 _R 18 _R 19 _R 20 _R 21 _R 22 _R 1A _R 2A _R 3A l\ . K , I\ l\ , K . l\ , K , IV . r\ , l\ , IV , IV , IV , 1V , 1V , 1V , IV , 1V , 1V , 1V , 1V , 1V ,

R ^B , R ^4A , R ^5A , R ^6A R ^7A and R ^8A represent substituents that can be attached to the indicated atom. An R group may be substituted or unsubstituted. If two "R" groups are described as being "taken together" the R groups and the atoms they are attached to can form a cycloalkyl, cycloalkenyl, aryl, heteroaryl or heterocycle. For example, without limitation, if R ¹⁸ and R ¹⁹ of an -C(R ¹⁸ )(R ¹⁹ )- group are indicated to be "taken together," it means that they are covalently bonded to one another to form a ring:

R 18. -R 19

V

[0023] Whenever a group is described as being "optionally substituted" that group may be unsubstituted or substituted with one or more of the indicated substituents. Likewise, when a group is described as being "unsubstituted or substituted" if substituted, the substituent(s) may be selected from one or more the indicated substituents. If no substituents are indicated, it is meant that the indicated "optionally substituted" or "substituted" group may be substituted with one or more group(s) individually and independently selected from alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, cycloalkynyl, aryl, heteroaryl, heteroalicyclyl, aralkyl, heteroaralkyl, (heteroalicyclyl)alkyl, hydroxy, protected hydroxyl, alkoxy, aryloxy, acyl, mercapto, alkylthio, arylthio, cyano, halogen, thiocarbonyl, O-carbamyl, N-carbamyl, O-thiocarbamyl, N-thiocarbamyl, C-amido, N-amido, S-sulfonamido, N-sulfonamido, C-carboxy, protected C-carboxy, O-carboxy, isocyanato, thiocyanato, isothiocyanato, nitro, silyl, sulfenyl, sulfmyl, sulfonyl, haloalkyl, haloalkoxy, trihalomethanesulfonyl, trihalomethanesulfonamido, an amino, a mono-substituted amino and a di-substituted amino group, and protected derivatives thereof.

[0024] As used herein, "C _a to C _b " in which "a" and "b" are integers refer to the number of carbon atoms in an alkyl, alkenyl or alkynyl group, or the number of carbon atoms in the ring of a cycloalkyl, cycloalkenyl, cycloalkynyl, aryl, heteroaryl or heteroalicyclyl group. That is, the alkyl, alkenyl, alkynyl, ring of the cycloalkyl, ring of the cycloalkenyl, ring of the cycloalkynyl, ring of the aryl, ring of the heteroaryl or ring of the heteroalicyclyl can contain from "a" to "b", inclusive, carbon atoms. Thus, for example, a "Ci to C4 alkyl" group refers to all alkyl groups having from 1 to 4 carbons, that is, CH ₃ -, CH ₃ CH ₂ -, CH ₃ CH ₂ CH ₂ -, (CH ₃ ) ₂ CH-, CH ₃ CH ₂ CH ₂ CH2-, CH ₃ CH ₂ CH(CH ₃ )- and (CH ₃ ) ₃ C-. If no "a" and "b" are designated with regard to an alkyl, alkenyl, alkynyl, cycloalkyl cycloalkenyl, cycloalkynyl, aryl, heteroaryl or heteroalicyclyl group, the broadest range described in these definitions is to be assumed.

[0025] As used herein, "alkyl" refers to a straight or branched hydrocarbon chain that comprises a fully saturated (no double or triple bonds) hydrocarbon group. The alkyl group may have 1 to 20 carbon atoms (whenever it appears herein, a numerical range such as "1 to 20" refers to each integer in the given range; e.g., "1 to 20 carbon atoms" means that the alkyl group may consist of 1 carbon atom, 2 carbon atoms, 3 carbon atoms, etc., up to and including 20 carbon atoms, although the present definition also covers the occurrence of the term "alkyl" where no numerical range is designated). The alkyl group may also be a medium size alkyl having 1 to 10 carbon atoms. The alkyl group could also be a lower alkyl having 1 to 6 carbon atoms. The alkyl group of the compounds may be designated as "C1-C4 alkyl" or similar designations. By way of example only, "C1-C4 alkyl" indicates that there are one to four carbon atoms in the alkyl chain, i.e., the alkyl chain is selected from methyl, ethyl, propyl, iso-propyl, n-butyl, iso-butyl, sec-butyl, and t-butyl. Typical alkyl groups include, but are in no way limited to, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tertiary butyl, pentyl and hexyl. The alkyl group may be substituted or unsubstituted.

[0026] As used herein, "alkenyl" refers to an alkyl group that contains in the straight or branched hydrocarbon chain one or more double bonds. An alkenyl group may be unsubstituted or substituted.

[0027] As used herein, "alkynyl" refers to an alkyl group that contains in the straight or branched hydrocarbon chain one or more triple bonds. An alkynyl group may be unsubstituted or substituted.

[0028] As used herein, "cycloalkyl" refers to a completely saturated (no double or triple bonds) mono- or multi-cyclic hydrocarbon ring system. When composed of two or more rings, the rings may be joined together in a fused fashion. Cycloalkyl groups can contain 3 to 10 atoms in the ring(s) or 3 to 8 atoms in the ring(s). A cycloalkyl group may be unsubstituted or substituted. Typical cycloalkyl groups include, but are in no way limited to, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl and cyclooctyl.

[0029] As used herein, "cycloalkenyl" refers to a mono- or multi- cyclic hydrocarbon ring system that contains one or more double bonds in at least one ring; although, if there is more than one, the double bonds cannot form a fully delocalized pi-electron system throughout all the rings (otherwise the group would be "aryl," as defined herein). When composed of two or more rings, the rings may be connected together in a fused fashion. A cycloalkenyl group may be unsubstituted or substituted.

[0030] As used herein, "cycloalkynyl" refers to a mono- or multi- cyclic hydrocarbon ring system that contains one or more triple bonds in at least one ring. If there is more than one triple bond, the triple bonds cannot form a fully delocalized pi-electron system throughout all the rings. When composed of two or more rings, the rings may be joined together in a fused fashion. A cycloalkynyl group may be unsubstituted or substituted.

[0031] As used herein, "aryl" refers to a carbocyclic (all carbon) monocyclic or multicyclic aromatic ring system (including fused ring systems where two carbocyclic rings share a chemical bond) that has a fully delocalized pi-electron system throughout all the rings. The number of carbon atoms in an aryl group can vary. For example, the aryl group can be a C6-C14 aryl group, a C6-C10 aryl group, or a Ce aryl group. Examples of aryl groups include, but are not limited to, benzene, naphthalene and azulene. An aryl group may be substituted or unsubstituted.

[0032] As used herein, "heteroaryl" refers to a monocyclic or multicyclic aromatic ring system (a ring system with fully delocalized pi-electron system) that contain(s) one or more heteroatoms, that is, an element other than carbon, including but not limited to, nitrogen, oxygen and sulfur. The number of atoms in the ring(s) of a heteroaryl group can vary. For example, the heteroaryl group can contain 4 to 14 atoms in the ring(s), 5 to 10 atoms in the ring(s) or 5 to 6 atoms in the ring(s). Furthermore, the term "heteroaryl" includes fused ring systems where two rings, such as at least one aryl ring and at least one heteroaryl ring, or at least two heteroaryl rings, share at least one chemical bond. Examples of heteroaryl rings include, but are not limited to, furan, furazan, thiophene, benzothiophene, phthalazine, pyrrole, oxazole, benzoxazole, 1 ,2,3-oxadiazole, 1,2,4-oxadiazole, thiazole, 1,2,3-thiadiazole, 1,2,4-thiadiazole, benzothiazole, imidazole, benzimidazole, indole, indazole, pyrazole, benzopyrazole, isoxazole, benzoisoxazole, isothiazole, triazole, benzotriazole, thiadiazole, tetrazole, pyridine, pyridazine, pyrimidine, pyrazine, purine, pteridine, quinoline, isoquinoline, quinazoline, quinoxaline, cinnoline, and triazine. A heteroaryl group may be substituted or unsubstituted.

[0033] As used herein, "heterocyclyl" or "heteroalicyclyl" refers to three-, four-, five-, six-, seven-, eight-, nine-, ten-, up to 18-membered monocyclic, bicyclic, and tricyclic ring system wherein carbon atoms together with from 1 to 5 heteroatoms constitute said ring system. A heterocycle may optionally contain one or more unsaturated bonds situated in such a way, however, that a fully delocalized pi-electron system does not occur throughout all the rings. The heteroatom(s) is an element other than carbon including, but not limited to, oxygen, sulfur, and nitrogen. A heterocycle may further contain one or more carbonyl or thiocarbonyl functionalities, so as to make the definition include oxo-systems and thio-systems such as lactams, lactones, cyclic imides, cyclic thioimides and cyclic carbamates. When composed of two or more rings, the rings may be joined together in a fused fashion. Additionally, any nitrogens in a heteroalicyclic may be quaternized. Heterocyclyl or heteroalicyclic groups may be unsubstituted or substituted. Examples of such "heterocyclyl" or "heteroalicyclyl" groups include but are not limited to, 1 ,3-dioxin, 1 ,3-dioxane, 1,4-dioxane, 1 ,2-dioxolane, 1 ,3- dioxolane, 1 ,4-dioxolane, 1 ,3-oxathiane, 1 ,4-oxathiin, 1 ,3-oxathiolane, 1,3-dithiole, 1 ,3- dithiolane, 1 ,4-oxathiane, tetrahydro- 1 ,4-thiazine, 2H- 1 ,2-oxazine, maleimide, succinimide, barbituric acid, thiobarbituric acid, dioxopiperazine, hydantoin, dihydrouracil, trioxane, hexahydro- 1 ,3, 5 -triazine, imidazoline, imidazolidine, isoxazoline, isoxazolidine, oxazoline, oxazolidine, oxazolidinone, thiazoline, thiazolidine, morpholine, oxirane, piperidine N-Oxide, piperidine, piperazine, pyrrolidine, pyrrolidone, pyrrolidione, 4-piperidone, pyrazoline, pyrazolidine, 2-oxopyrrolidine, tetrahydropyran, 4H-pyran, tetrahydrothiopyran, thiamorpholine, thiamorpholine sulfoxide, thiamorpholine sulfone, and their benzo-fused analogs (e.g., benzimidazolidinone, tetrahydroquinoline, 3,4-methylenedioxyphenyl). [0034] As used herein, "aralkyl" and "aryl(alkyl)" refer to an aryl group connected, as a substituent, via a lower alkylene group. The lower alkylene and aryl group of an aralkyl may be substituted or unsubstituted. Examples include but are not limited to benzyl, 2- phenylalkyl, 3-phenylalkyl, and naphthylalkyl.

[0035] As used herein, "heteroaralkyl" and "heteroaryl(alkyl)" refer to a heteroaryl group connected, as a substituent, via a lower alkylene group. The lower alkylene and heteroaryl group of heteroaralkyl may be substituted or unsubstituted. Examples include but are not limited to 2-thienylalkyl, 3-thienylalkyl, furylalkyl, thienylalkyl, pyrrolylalkyl, pyridylalkyl, isoxazolylalkyl, and imidazolylalkyl, and their benzo-fused analogs.

[0036] A "(heteroalicyclyl)alkyl" and "(heterocyclyl)alkyl" refer to a heterocyclic or a heteroalicyclylic group connected, as a substituent, via a lower alkylene group. The lower alkylene and heterocyclyl of a (heteroalicyclyl)alkyl may be substituted or unsubstituted. Examples include but are not limited tetrahydro-2H-pyran-4-yl)methyl, (piperidin-4-yl)ethyl, (piperidin-4-yl)propyl, (tetrahydro-2H-thiopyran-4-yl)methyl, and (l ,3-thiazinan-4-yl)methyl.

[0037] "Lower alkylene groups" are straight-chained -CH ₂ - tethering groups, forming bonds to connect molecular fragments via their terminal carbon atoms. Examples include but are not limited to methylene (-CH ₂ -), ethylene (-CH2CH2-), propylene (- CH ₂ CH ₂ CH ₂ -), and butylene (-CH ₂ CH ₂ CH ₂ CH ₂ -). A lower alkylene group can be substituted by replacing one or more hydrogen of the lower alkylene group with a substituent(s) listed under the definition of "substituted."

[0038] As used herein, "alkoxy" refers to the formula -OR wherein R is an alkyl, an alkenyl, an alkynyl, a cycloalkyl, a cycloalkenyl or a cycloalkynyl is defined as above. A non- limiting list of alkoxys are methoxy, ethoxy, n-propoxy, 1-methylethoxy (isopropoxy), n- butoxy, iso-butoxy, sec-butoxy, tert-butoxy, and the like. An alkoxy may be substituted or unsubstituted.

[0039] As used herein, "acyl" refers to a hydrogen, alkyl, alkenyl, alkynyl, or aryl connected, as substituents, via a carbonyl group. Examples include formyl, acetyl, propanoyl, benzoyl, and acryl. An acyl may be substituted or unsubstituted.

[0040] As used herein, "hydroxyalkyl" refers to an alkyl group in which one or more of the hydrogen atoms are replaced by a hydroxy group. Exemplary hydroxyalkyl groups include but are not limited to, 2-hydroxyethyl, 3-hydroxypropyl, 2-hydroxypropyl, and 2,2- dihydroxy ethyl. A hydroxyalkyl may be substituted or unsubstituted.

[0041] As used herein, "haloalkyl" refers to an alkyl group in which one or more of the hydrogen atoms are replaced by a halogen (e.g., mono-haloalkyl, di-haloalkyl and tri- haloalkyl). Such groups include but are not limited to, chloromethyl, fluoromethyl, difluoromethyl, trifluoromethyl, l-chloro-2-fluoromethyl and 2-fluoroisobutyl. A haloalkyl may be substituted or unsubstituted.

[0042] As used herein, "haloalkoxy" refers to an alkoxy group in which one or more of the hydrogen atoms are replaced by a halogen (e.g., mono-haloalkoxy, di- haloalkoxy and tri- haloalkoxy). Such groups include but are not limited to, chloromethoxy, fluoromethoxy, difluoromethoxy, trifluoromethoxy, l-chloro-2-fluoromethoxy and 2-fluoroisobutoxy. A haloalkoxy may be substituted or unsubstituted.

[0043] As used herein, "aryloxy" and "arylthio" refers to RO- and RS-, in which R is an aryl, such as, but not limited to, phenyl. Both an aryloxy and arylthio may be substituted or unsubstituted.

[0044] A "sulfenyl" group refers to an "-SR" group in which R can be hydrogen, alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, cycloalkynyl, aryl, heteroaryl, heteroalicyclyl, aralkyl, or (heteroalicyclyl)alkyl. A sulfenyl may be substituted or unsubstituted.

[0045] A "sulfinyl" group refers to an "-S(=0)-R" group in which R can be the same as defined with respect to sulfenyl. A sulfinyl may be substituted or unsubstituted.

[0046] A "sulfonyl" group refers to an "SO ₂ R" group in which R can be the same as defined with respect to sulfenyl. A sulfonyl may be substituted or unsubstituted.

[0047] An "O-carboxy" group refers to a "RC(=0)0-" group in which R can be hydrogen, alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, cycloalkynyl, aryl, heteroaryl, heteroalicyclyl, aralkyl, or (heteroalicyclyl)alkyl, as defined herein. An O-carboxy may be substituted or unsubstituted.

[0048] The terms "ester" and "C-carboxy" refer to a "-C(=0)OR" group in which R can be the same as defined with respect to O-carboxy. An ester and C-carboxy may be substituted or unsubstituted.

[0049] A "thiocarbonyl" group refers to a "-C(=S)R" group in which R can be the same as defined with respect to O-carboxy. A thiocarbonyl may be substituted or unsubstituted.

[0050] A "trihalomethanesulfonyl" group refers to an "X ₃ CSO ₂ -" group wherein each X is a halogen.

[0051] A "trihalomethanesulfonamido" group refers to an "X ₃ CS(0) ₂ N(RA)-" group wherein each X is a halogen, and RA hydrogen, alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, cycloalkynyl, aryl, heteroaryl, heteroalicyclyl, aralkyl, or (heteroalicyclyl)alkyl.

[0052] The term "amino" as used herein refers to a -Nl¾ group.

[0053] As used herein, the term "hydroxy" refers to a -OH group. [0054] A "cyano" group refers to a "-CN" group.

[0055] The term "azido" as used herein refers to a -N ₃ group.

[0056] The term "allenyl" as used herein refers to a R2C=C=CR- group in which each R can be independently hydrogen, alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, cycloalkynyl, aryl, heteroaryl, heterocyclyl, aralkyl, or (heterocyclyl)alkyl.

[0057] An "isocyanato" group refers to a "-NCO" group.

[0058] A "thiocyanato" group refers to a "-CNS" group.

[0059] An "isothiocyanato" group refers to an " -NCS" group.

[0060] A "mercapto" group refers to an "-SH" group.

[0061] A "carbonyl" group refers to a C=0 group.

[0062] An "S-sulfonamido" group refers to a "-S0 ₂ N(RARB)" group in which R _A and RB can be independently hydrogen, alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, cycloalkynyl, aryl, heteroaryl, heteroalicyclyl, aralkyl, or (heteroalicyclyl)alkyl. An S-sulfonamido may be substituted or unsubstituted.

[0063] An "N-sulfonamido" group refers to a "RSC>2N(RA)-" group in which R and RA can be independently hydrogen, alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, cycloalkynyl, aryl, heteroaryl, heteroalicyclyl, aralkyl, or (heteroalicyclyl)alkyl. An N-sulfonamido may be substituted or unsubstituted.

[0064] An "O-carbamyl" group refers to a "-OC(=0)N(R _A R _B )" group in which R _A and R _B can be independently hydrogen, alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, cycloalkynyl, aryl, heteroaryl, heteroalicyclyl, aralkyl, or (heteroalicyclyl)alkyl. An O-carbamyl may be substituted or unsubstituted.

[0065] An "N-carbamyl" group refers to an "ROC(=0)N(R _A ) -" group in which R and R _A can be independently hydrogen, alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, cycloalkynyl, aryl, heteroaryl, heteroalicyclyl, aralkyl, or (heteroalicyclyl)alkyl. An N-carbamyl may be substituted or unsubstituted.

[0066] An "O-thiocarbamyl" group refers to a "-OC(=S)-N(R _A R _B )" group in which RA and RB can be independently hydrogen, alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, cycloalkynyl, aryl, heteroaryl, heteroalicyclyl, aralkyl, or (heteroalicyclyl)alkyl. An O-thiocarbamyl may be substituted or unsubstituted.

[0067] An "N-thiocarbamyl" group refers to an "ROC(=S)N(R _A )-" group in which R and RA can be independently hydrogen, alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, cycloalkynyl, aryl, heteroaryl, heteroalicyclyl, aralkyl, or (heteroalicyclyl)alkyl. An N-thiocarbamyl may be substituted or unsubstituted. [0068] A "C-amido" group refers to a "-C(=0)N(R _A RB)" group in which R _A and R _B can be independently hydrogen, alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, cycloalkynyl, aryl, heteroaryl, heteroalicyclyl, aralkyl, or (heteroalicyclyl)alkyl. A C-amido may be substituted or unsubstituted.

[0069] An "N-amido" group refers to a "RC(=0)N(R _A )-" group in which R and R _A can be independently hydrogen, alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, cycloalkynyl, aryl, heteroaryl, heteroalicyclyl, aralkyl, or (heteroalicyclyl)alkyl. An N-amido may be substituted or unsubstituted.

[0070] The term "halogen atom" or "halogen" as used herein, means any one of the radio-stable atoms of column 7 of the Periodic Table of the Elements, such as, fluorine, chlorine, bromine and iodine.

[0071] Where the numbers of substituents is not specified (e.g., haloalkyl), there may be one or more substituents present. For example "haloalkyl" may include one or more of the same or different halogens. As another example, "C1-C3 alkoxyphenyl" may include one or more of the same or different alkoxy groups containing one, two or three atoms.

[0072] As used herein, the abbreviations for any protective groups, amino acids and other compounds, are, unless indicated otherwise, in accord with their common usage, recognized abbreviations, or the IUPAC-IUB Commission on Biochemical Nomenclature (See, Biochem. 1 1 :942-944 (1972)).

[0073] The term "nucleoside" is used herein in its ordinary sense as understood by those skilled in the art, and refers to a compound composed of an optionally substituted pentose moiety or modified pentose moiety attached to a heterocyclic base or tautomer thereof via a N- glycosidic bond, such as attached via the 9-position of a purine-base or the 1 -position of a pyrimidine-base. Examples include, but are not limited to, a ribonucleoside comprising a ribose moiety and a deoxyribonucleoside comprising a deoxyribose moiety. A modified pentose moiety is a pentose moiety in which an oxygen atom has been replaced with a carbon and/or a carbon has been replaced with a sulfur or an oxygen atom. A "nucleoside" is a monomer that can have a substituted base and/or sugar moiety. Additionally, a nucleoside can be incorporated into larger DNA and/or RNA polymers and oligomers. In some instances, the nucleoside can be a nucleoside analog drug.

[0074] As used herein, the term "heterocyclic base" refers to an optionally substituted nitrogen-containing heterocyclyl that can be attached to an optionally substituted pentose moiety or modified pentose moiety. In some embodiments, the heterocyclic base can be selected from an optionally substituted purine-base, an optionally substituted pyrimidine-base and an optionally substituted triazole-base (for example, a 1 ,2,4-triazole). The term "purine- base" is used herein in its ordinary sense as understood by those skilled in the art, and includes its tautomers. Similarly, the term "pyrimidine-base" is used herein in its ordinary sense as understood by those skilled in the art, and includes its tautomers. A non-limiting list of optionally substituted purine-bases includes purine, adenine, guanine, hypoxanthine, xanthine, alloxanthine, 7-alkylguanine (e.g., 7-methylguanine), theobromine, caffeine, uric acid and isoguanine. Examples of pyrimidine-bases include, but are not limited to, cytosine, thymine, uracil, 5,6-dihydrouracil and 5-alkylcytosine (e.g., 5-methylcytosine). An example of an optionally substituted triazole-base is l ,2,4-triazole-3-carboxamide. Other non-limiting examples of heterocyclic bases include diaminopurine, 8-oxo-N ⁶ -alkyladenine (e.g., 8-oxo-N ⁶ - methyladenine), 7-deazaxanthine, 7-deazaguanine, 7-deazaadenine, N ⁴ ,N ⁴ -ethanocytosin, N ⁶ ,N ⁶ - ethano-2,6-diaminopurine, 5-halouracil (e.g., 5-fluorouracil and 5-bromouracil), pseudoisocytosine, isocytosine, isoguanine, and other heterocyclic bases described in U.S. Patent Nos. 5,432,272 and 7,125,855, which are incorporated herein by reference for the limited purpose of disclosing additional heterocyclic bases. In some embodiments, a heterocyclic base can be optionally substituted with an amine or an enol protecting group(s).

[0075] The term "-N-linked amino acid" refers to an amino acid that is attached to the indicated moiety via a main-chain amino or mono-substituted amino group. When the amino acid is attached in an -N-linked amino acid, one of the hydrogens that is part of the main-chain amino or mono-substituted amino group is not present and the amino acid is attached via the nitrogen. As used herein, the term "amino acid" refers to any amino acid (both standard and non-standard amino acids), including, but not limited to, a-amino acids, β-amino acids, γ-amino acids and δ-amino acids. Examples of suitable amino acids include, but are not limited to, alanine, asparagine, aspartate, cysteine, glutamate, glutamine, glycine, proline, serine, tyrosine, arginine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine. Additional examples of suitable amino acids include, but are not limited to, ornithine, hypusine, 2-aminoisobutyric acid, dehydroalanine, gamma-aminobutyric acid, citrulline, beta-alanine, alpha-ethyl-glycine, alpha-propyl-glycine and norleucine. N-linked amino acids can be substituted or unsubstituted.

[0076] The term "-N-linked amino acid ester derivative" refers to an amino acid in which a main-chain carboxylic acid group has been converted to an ester group. In some embodiments, the ester group has a formula selected from alkyl-0-C(=0)-, cycloalkyl-0-C(=0)- , aryl-0-C(=0)- and aryl(alkyl)-0-C(=0)-. A non-limiting list of ester groups include substituted and unsubstituted versions of the following: methyl-0-C(=0)-, ethyl-0-C(=0)-, n- propyl-0-C(=0)-, isopropyl-0-C(=0)-, n-butyl-0-C(=0)-, isobutyl-0-C(=0)-, tert-butyl-O- C(=0)-, neopentyl-0-C(=0)-, cyclopropyl-0-C(=0)-, cyclobutyl-0-C(=0)-, cyclopentyl-O- C(=0)-, cyclohexyl-0-C(=0)-, phenyl-0-C(=0)-, benzyl-0-C(=0)-, and naphthyl-0-C(=0)-. N-linked amino acid ester derivatives can be substituted or unsubstituted.

[0077] The terms "protecting group" and "protecting groups" as used herein refer to any atom or group of atoms that is added to a molecule in order to prevent existing groups in the molecule from undergoing unwanted chemical reactions. Examples of protecting group moieties are described in T. W. Greene and P. G. M. Wuts, Protective Groups in Organic Synthesis, 3. Ed. John Wiley & Sons, 1999, and in J.F.W. McOmie, Protective Groups in Organic Chemistry Plenum Press, 1973, both of which are hereby incorporated by reference for the limited purpose of disclosing suitable protecting groups. The protecting group moiety may be chosen in such a way, that they are stable to certain reaction conditions and readily removed at a convenient stage using methodology known from the art. A non-limiting list of protecting groups include benzyl; substituted benzyl; alkylcarbonyls and alkoxycarbonyls (e.g., t-butoxycarbonyl (BOC), acetyl, or isobutyryl); arylalkylcarbonyls and arylalkoxycarbonyls (e.g., benzyloxycarbonyl); substituted methyl ether (e.g., methoxymethyl ether); substituted ethyl ether; a substituted benzyl ether; tetrahydropyranyl ether; silyls (e.g., trimethylsilyl, triethylsilyl, triisopropylsilyl, t- butyldimethylsilyl, tri-z ^' so-propylsilyloxymethyl, [2-(trimethylsilyl)ethoxy]methyl or t- butyldiphenylsilyl); esters (e.g., benzoate ester); carbonates (e.g., methoxymethylcarbonate); sulfonates (e.g., tosylate or mesylate); acyclic ketal (e.g., dimethyl acetal); cyclic ketals (e.g., 1,3-dioxane, 1 ,3-dioxolanes, and those described herein); acyclic acetal; cyclic acetal (e.g., those described herein); acyclic hemiacetal; cyclic hemiacetal; cyclic dithioketals (e.g., 1 ,3-dithiane or 1,3-dithiolane); orthoesters (e.g., those described herein) and triarylmethyl groups (e.g., trityl; monomethoxytrityl (MMTr); 4,4'-dimethoxytrityl (DMTr); 4,4',4"-trimethoxytrityl (TMTr); and those described herein).

[0078] "Leaving group" as used herein refers to any atom or moiety that is capable of being displaced by another atom or moiety in a chemical reaction. More specifically, in some embodiments, "leaving group" refers to the atom or moiety that is displaced in a nucleophilic substitution reaction. In some embodiments, "leaving groups" are any atoms or moieties that are conjugate bases of strong acids. Examples of suitable leaving groups include, but are not limited to, tosylates and halogens. Non-limiting characteristics and examples of leaving groups can be found, for example in Organic Chemistry, 2d ed., Francis Carey (1992), pages 328-331 ; Introduction to Organic Chemistry, 2d ed., Andrew Streitwieser and Clayton Heathcock (1981), pages 169-171 ; and Organic Chemistry, 5 ^th ed., John McMurry (2000), pages 398 and 408; all of which are incorporated herein by reference for the limited purpose of disclosing characteristics and examples of leaving groups.

[0079] The term "pharmaceutically acceptable salt" refers to a salt of a compound that does not cause significant irritation to an organism to which it is administered and does not abrogate the biological activity and properties of the compound. In some embodiments, the salt is an acid addition salt of the compound. Pharmaceutical salts can be obtained by reacting a compound with inorganic acids such as a hydrohalic acid (e.g., hydrochloric acid or hydrobromic acid), sulfuric acid, nitric acid and phosphoric acid. Pharmaceutical salts can also be obtained by reacting a compound with an organic acid such as aliphatic or aromatic carboxylic or sulfonic acids, for example formic, acetic, succinic, lactic, malic, tartaric, citric, ascorbic, nicotinic, methanesulfonic, ethanesulfonic, p-toluensulfonic, salicylic or naphthalenesulfonic acid. Pharmaceutical salts can also be obtained by reacting a compound with a base to form a salt such as an ammonium salt, an alkali metal salt, such as a sodium or a potassium salt, an alkaline earth metal salt, such as a calcium or a magnesium salt, a salt of organic bases such as dicyclohexylamine, N-methyl-D-glucamine, tris(hydroxymethyl)methylamine, C 1-C7 alkylamine, cyclohexylamine, triethanolamine, ethylenediamine, and salts with amino acids such as arginine and lysine.

[0080] Terms and phrases used in this application, and variations thereof, especially in the appended claims, unless otherwise expressly stated, should be construed as open ended as opposed to limiting. As examples of the foregoing, the term 'including' should be read to mean 'including, without limitation,' 'including but not limited to,' or the like; the term 'comprising' as used herein is synonymous with 'including,' 'containing,' or 'characterized by,' and is inclusive or open-ended and does not exclude additional, unrecited elements or method steps; the term 'having' should be interpreted as 'having at least;' the term 'includes' should be interpreted as 'includes but is not limited to;' the term 'example' is used to provide exemplary instances of the item in discussion, not an exhaustive or limiting list thereof; and use of terms like 'preferably,' 'preferred,' 'desired,' or 'desirable,' and words of similar meaning should not be understood as implying that certain features are critical, essential, or even important to the structure or function of the invention, but instead as merely intended to highlight alternative or additional features that may or may not be utilized in a particular embodiment. In addition, the term "comprising" is to be interpreted synonymously with the phrases "having at least" or "including at least". When used in the context of a process, the term "comprising" means that the process includes at least the recited steps, but may include additional steps. When used in the context of a compound, composition or device, the term "comprising" means that the compound, composition or device includes at least the recited features or components, but may also include additional features or components. Likewise, a group of items linked with the conjunction 'and' should not be read as requiring that each and every one of those items be present in the grouping, but rather should be read as 'and/or' unless expressly stated otherwise. Similarly, a group of items linked with the conjunction Or' should not be read as requiring mutual exclusivity among that group, but rather should be read as 'and/or' unless expressly stated otherwise.

[0081] With respect to the use of substantially any plural and/or singular terms herein, those having skill in the art can translate from the plural to the singular and/or from the singular to the plural as is appropriate to the context and/or application. The various singular/plural permutations may be expressly set forth herein for sake of clarity. The indefinite article "a" or "an" does not exclude a plurality. A single processor or other unit may fulfill the functions of several items recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. Any reference signs in the claims should not be construed as limiting the scope.

[0082] It is understood that, in any compound described herein having one or more chiral centers, if an absolute stereochemistry is not expressly indicated, then each center may independently be of R-configuration or S-configuration or a mixture thereof. Thus, the compounds provided herein may be enantiomerically pure, enantiomerically enriched, racemic mixture, diastereomerically pure, diastereomerically enriched, or a stereoisomeric mixture. In addition it is understood that, in any compound described herein having one or more double bond(s) generating geometrical isomers that can be defined as E or Z, each double bond may independently be E or Z a mixture thereof.

[0083] Likewise, it is understood that, in any compound described, all tautomeric forms are also intended to be included. For example all tautomers of phosphate groups are intended to be included. Furthermore, all tautomers of heterocyclic bases known in the art are intended to be included, including tautomers of natural and non-natural purine-bases and pyrimidine-bases .

[0084] It is to be understood that where compounds disclosed herein have unfilled valencies, then the valencies are to be filled with hydrogens or isotopes thereof, e.g., hydrogen-1 (protium) and hydrogen-2 (deuterium).

[0085] It is understood that the compounds described herein can be labeled isotopically. Substitution with isotopes such as deuterium may afford certain therapeutic advantages resulting from greater metabolic stability, such as, for example, increased in vivo half-life or reduced dosage requirements. Each chemical element as represented in a compound structure may include any isotope of said element. For example, in a compound structure a hydrogen atom may be explicitly disclosed or understood to be present in the compound. At any position of the compound that a hydrogen atom may be present, the hydrogen atom can be any isotope of hydrogen, including but not limited to hydrogen- 1 (protium) and hydrogen-2 (deuterium). Thus, reference herein to a compound encompasses all potential isotopic forms unless the context clearly dictates otherwise.

[0086] It is understood that the methods and combinations described herein include crystalline forms (also known as polymorphs, which include the different crystal packing arrangements of the same elemental composition of a compound), amorphous phases, salts, solvates, and hydrates. In some embodiments, the compounds described herein exist in solvated forms with pharmaceutically acceptable solvents such as water, ethanol, or the like. In other embodiments, the compounds described herein exist in unsolvated form. Solvates contain either stoichiometric or non-stoichiometric amounts of a solvent, and may be formed during the process of crystallization with pharmaceutically acceptable solvents such as water, ethanol, or the like. Hydrates are formed when the solvent is water, or alcoholates are formed when the solvent is alcohol. In addition, the compounds provided herein can exist in unsolvated as well as solvated forms. In general, the solvated forms are considered equivalent to the unsolvated forms for the purposes of the compounds and methods provided herein.

[0087] Where a range of values is provided, it is understood that the upper and lower limit, and each intervening value between the upper and lower limit of the range is encompassed within the embodiments.

[0088] Some embodiments disclosed herein relate to a compound of Formula (I) or a pharmaceutically acceptable salt thereof:

wherein: B ¹ can be an optionally substituted heterocyclic base or an optionally substituted heterocyclic base with a protected amino group; X ¹ can be O (oxygen) or S (sulfur); R ¹ can be selected from -Z ^x -R ⁹ , an optionally substituted N-linked amino acid and an optionally substituted N-linked amino acid ester derivative; Z ¹ can be selected from O (oxygen), S (sulfur) and N(R ¹⁰ ); R ² and R ³ can be independently selected from hydrogen, an optionally substituted Ci-6 alkyl, an optionally substituted C2-6 alkenyl, an optionally substituted C2-6 alkynyl, an optionally substituted Ci_6 haloalkyl and an optionally substituted aryl(Ci_6 alkyl); or R ² and R ³ can be taken together to form a group selected from an optionally substituted C3-6 cycloalkyl, an optionally substituted C ₃ _6 cycloalkenyl, an optionally substituted C _6 aryl and an optionally substituted C ₃ -6 heteroaryl; R ⁴ can be selected from hydrogen, halogen, azido, cyano, an optionally substituted Ci_6 alkyl, an optionally substituted C ₂ -6 alkenyl, an optionally substituted C2-6 alkynyl and an optionally substituted allenyl; R ⁵ can be hydrogen or an optionally substituted Ci_6 alkyl; R ⁶ can be selected from hydrogen, halogen, azido, amino, cyano, an optionally substituted Ci_6 alkyl, -OR ¹¹ and -OC(=0)R ¹² ; R ⁷ can be selected from hydrogen, halogen, azido, cyano, an optionally substituted Ci_6 alkyl, -OR ¹³ and -OC(=0)R ¹⁴ ; R ⁸ can be selected from hydrogen, halogen, azido, cyano, an optionally substituted Ci_6 alkyl, -OR ¹⁵ and - OC(=0)R ¹⁵ ; R ⁹ can be selected from an optionally substituted alkyl, an optionally substituted alkenyl, an optionally substituted alkynyl, an optionally substituted cycloalkyl, an optionally substituted cycloalkenyl, an optionally substituted aryl, an optionally substituted heteroaryl, an optionally substituted heterocyclyl, an optionally substituted aryl(Ci_6 alkyl), an optionally substituted heteroaryl(Ci_6 alkyl), an optionally substituted heterocyclyl(Ci_6 alkyl), and Formula (II); R ¹⁰ can be selected from hydrogen, an optionally substituted alkyl, an optionally substituted alkenyl, an optionally substituted alkynyl, an optionally substituted cycloalkyl, an optionally substituted cycloalkenyl, an optionally substituted aryl, an optionally substituted heteroaryl, an optionally substituted heterocyclyl, an optionally substituted aryl(Ci_6 alkyl), an optionally substituted heteroaryl(Ci_6 alkyl) and an optionally substituted heterocyclyl(Ci_6 alkyl); R ¹¹ , R ¹³ and R ¹⁵ can be independently hydrogen or an optionally substituted Ci_6 alkyl; R ¹² , R ¹⁴ and R ¹⁶ can be independently an optionally substituted Ci_e alkyl or an optionally substituted C ₃ -6 cycloalkyl; and Formula (II) can be:

wherein: R and R can be independently selected from a hydrogen, an optionally substituted Ci-24 alkyl and an optionally substituted aryl; R ²² can be selected from a hydrogen, an optionally substituted Ci_24 alkyl, an optionally substituted aryl, an optionally substituted -O-Ci-24 alkyl and an optionally substituted -O-aryl; and Y can be O (oxygen) or S (sulfur).

[0089] In some embodiments, a compound of Formula (I) cannot have a structure selected from:

-19-

and R ¹⁰ is hydrogen, then R ⁹ cannot be an optionally substituted phenyl. In some embodiments, when X ¹ is S (sulfur), Z ¹ is N(R ¹⁰ ) and R ¹⁰ is hydrogen, then R ⁹ cannot be an unsubstituted aryl, for example an unsubstituted phenyl. In other embodiments, when X ¹ is S (sulfur), R ¹ is -Z'-R ⁹ and Z ¹ is N(R ¹⁰ ), then R ⁹ and R ¹⁰ cannot both be methyl or ethyl. In some embodiments, when X ¹ is S (sulfur), R ¹ is -Z^R ⁹ and Z ¹ is N(R ¹⁰ ), then R ⁹ and R ¹⁰ cannot both be an unsubstituted Ci-4 alkyl. In some embodiments, when X ¹ is S (sulfur), R ¹ is -Z -R ⁹ and Z ¹ is N(R ¹⁰ ), then R ⁹ and R ¹⁰ cannot both be an optionally substituted C _1-4 alkyl. In some embodiments, when X ¹ is S (sulfur), R ¹ is -Z^R ⁹ and Z ¹ is N(R ¹⁰ ), then R ⁹ and R ¹⁰ cannot both be an unsubstituted alkyl. In some embodiments, when X ¹ is S (sulfur), R ¹ is -Z^R ⁹ and Z ¹ is N(R ¹⁰ ), then R ⁹ and R ¹⁰ cannot both be an optionally substituted alkyl.

[0091] In some embodiments, when X ¹ is S (sulfur), R ¹ is -Z ^x -R ⁹ and Z ¹ is O (oxygen), then R ⁹ cannot be methyl. In some embodiments, when X ¹ is S (sulfur), R ¹ is -Z'-R ⁹ and Z ¹ is O (oxygen), then R ⁹ cannot be an unsubstituted alkyl, for example an unsubstituted Ci_ 4 alkyl. In some embodiments, when X ¹ is S (sulfur), R ¹ is -Z ^x -R ⁹ and Z ¹ is O (oxygen), then R ⁹ cannot be an optionally substituted alkyl, for example an optionally substituted Ci_ ₄ alkyl. In other embodiments, when X ¹ is S (sulfur), R ¹ is -Z^R ⁹ and Z ¹ is O (oxygen), then R ⁹ cannot be -CH ₂ -OC(=0)-(Ci_4 alkyl), such as -CH ₂ -OC(=0)CH ₃ or -CH ₂ -OC(=0)C(CH ₃ ). In some embodiments, when X ¹ is S (sulfur), R ¹ is -Z ^J -R ⁹ and Z ¹ is O (oxygen), then R ⁹ cannot be - alkyl), such as -CH ₂ -OC(=0)-0-isopropyl. In still other embodiments, when X ¹ is S (sulfur), R ¹ is -Z ^x -R ⁹ and Z ¹ is O (oxygen), then R ⁹ cannot be -CH ₂ CH=CH ₂ . In some embodiments, when X ¹ is S (sulfur), R ¹ is -Z^R ⁹ and Z ¹ is O (oxygen), then R ⁹ cannot be an unsubstituted C _1-4 alkenyl. In some embodiments, when X ¹ is S (sulfur), R ¹ is -Z^R ⁹ and Z ¹ is O (oxygen), then R ⁹ cannot be an unsubstituted alkenyl. In other embodiments, when X ¹ is S (sulfur), R ¹ is -Z^R ⁹ and Z ¹ is O (oxygen), then R ⁹ cannot be 2-chlorophenyl. In some embodiments, when X ¹ is S (sulfur), R ¹ is -Z ^x -R ⁹ and Z ¹ is O (oxygen), then R ⁹ cannot be an optionally substituted aryl, such as an unsubstituted or substituted phenyl.

[0092] In some embodiments, when X ¹ is O (oxygen), R ¹ is -Z ^x -R ⁹ , Z ¹ is N(R ¹⁰ ) and R ¹⁰ is hydrogen, then R ⁹ cannot be an optionally substituted phenyl. In some embodiments, when X ¹ is O (oxygen), R ¹ is -Z ^x -R ⁹ , Z ¹ is N(R ¹⁰ ) and R ¹⁰ is hydrogen, then R ⁹ cannot be an optionally substituted aryl, such as an unsubstituted or substituted phenyl. In other embodiments, when X ¹ is O (oxygen), R ¹ is -Z^R ⁹ , Z ¹ is N(R ¹⁰ ) and R ¹⁰ is hydrogen, then R ⁹ cannot be an optionally substituted benzyl. In some embodiments, when X ¹ is O (oxygen), R ¹ is -Z ^x -R ⁹ , Z ¹ is N(R ¹⁰ ) and R ¹⁰ is hydrogen, then R ⁹ cannot be an unsubstituted aryl(Ci_6 alkyl). In still other embodiments, when X ¹ is O (oxygen), R ¹ is -Z ^L -R ⁹ , Z ¹ is N(R ¹⁰ ) and R ¹⁰ is hydrogen, then R ⁹ cannot be a substituted aryl(Ci_e alkyl). In yet still other embodiments, when X ¹ is O (oxygen), R ¹ is -Z ^x -R ⁹ and Z ¹ is N(R ¹⁰ ), then R ⁹ and R ¹⁰ cannot be an unsubstituted Ci_ ₄ alkyl. Examples of C _1-4 alkyls are described herein. In some embodiments, when X ¹ is O (oxygen), R ¹ is -Z ^x -R ⁹ and Z ¹ is N(R ¹⁰ ), then R ⁹ and R ¹⁰ cannot both be an optionally substituted alkyl, such as an optionally substituted C _1-4 alkyl.

[0093] In some embodiments, when X ¹ is O (oxygen), R ¹ is -Z^R ⁹ and Z ¹ is O (oxygen), then R ⁹ cannot be methyl. In some embodiments, when X ¹ is O (oxygen), R ¹ is -Z ¹ - R ⁹ and Z ¹ is O (oxygen), then R ⁹ cannot be an unsubstituted Ci_4 alkyl. In some embodiments, when X ¹ is O (oxygen), R ¹ is -Z ^L -R ⁹ and Z ¹ is O (oxygen), then R ⁹ cannot be an optionally substituted alkyl, such as an optionally substituted C _1-4 alkyl. In other embodiments, when X ¹ is O (oxygen), R ¹ is -Z -R ⁹ and Z ¹ is O (oxygen), then R ⁹ cannot be -CH ₂ -OC(=0)-(Ci_ ₄ alkyl), such as -CH ₂ -OC(=0)CH ₃ , or -CH ₂ -OC(=0)C(CH ₃ ). In some embodiments, when X ¹ is O (oxygen), R ¹ is -Z ^x -R ⁹ and Z ¹ is O (oxygen), then R ⁹ cannot be -CH ₂ -OC(=0)-0-(Ci_ ₆ alkyl), such as -CH ₂ -OC(=0)-0-isopropyl. In still other embodiments, when X ¹ is O (oxygen), R ¹ is - Z^R ⁹ and Z ¹ is O (oxygen), then R ⁹ cannot be an optionally substituted phenyl. In some embodiments, when X ¹ is O (oxygen), R ¹ is -Z ^x -R ⁹ and Z ¹ is O (oxygen), then R ⁹ cannot be an unsubstituted aryl. In yet still other embodiments, when X ¹ is O (oxygen), R ¹ is -Z ^x -R ⁹ and Z ¹ is O (oxygen), then R ⁹ cannot be an optionally substituted aryl(Ci_6 alkyl), for example, an optionally substituted benzyl.

[0094] In some embodiments, when X ¹ is O (oxygen), R ¹ is -Z ^x -R ⁹ and Z ¹ is S (sulfur), then R ⁹ cannot be methyl. In some embodiments, when X ¹ is O (oxygen), R ¹ is -Z ^J -R ⁹ and Z ¹ is S (sulfur), then R ⁹ cannot be an unsubstituted Ci_ ₄ alkyl. Examples of C _1-4 alkyl groups are described herein. In some embodiments, when X ¹ is O (oxygen), R ¹ is -Z ^x -R ⁹ and Z ¹ is S (sulfur), then R ⁹ cannot be an optionally substituted alkyl. In other embodiments, when X ¹ is O (oxygen), R ¹ is -Z ^x -R ⁹ and Z ¹ is S (sulfur), then R ⁹ cannot be -CH ₂ -C(=0)-C(=0)-CH ₂ -halo, such as -CH ₂ -C(=0)-C(=0)-CH ₂ Br, -CH ₂ -C(=0)-C(=0)-CH ₂ C1, -CH ₂ -C(=0)-C(=0)- CH ₂ F, or -CH ₂ -C(=0)-C(=0)-CH ₂ I. In other embodiments, when X ¹ is O (oxygen), R ¹ is -Z ¹ - R ⁹ and Z ¹ is S (sulfur), then R ⁹ cannot be -CH ₂ -OC(=0)-t-butyl, -CH ₂ -OC(=0)-methyl, - alkyl). In still other embodiments, when X ¹ is O (oxygen), R ¹ is -Z'-R ⁹ and Z ¹ is S (sulfur), then R ⁹ cannot be 4-nitro-benzyl or 4-isobutyryloxy-benzyl. In some embodiments, when X ¹ is O (oxygen), R ¹ is -Z ^L -R ⁹ and Z ¹ is S (sulfur), then R ⁹ cannot be an optionally substituted aryl(Ci_6 alkyl).

[0095] The compound of Formula (I) can have various phosphorous containing groups. For example, the cyclic phosphorous containing group can be a cyclic phosphate, a cyclic phosphorothioate, a cyclic phosphoramidate or a cyclic thiophosphoramidate. In some embodiments, X ¹ can be O (oxygen). In some embodiments, X ¹ can be O (oxygen), and R ¹ can be -Z ^x -R ⁹ . In some embodiments, X can be O (oxygen), R can be -Z'-R ⁹ , and Z ¹ can be O (oxygen). In other embodiments, X ¹ can be O (oxygen), R ¹ can be -Z ^x -R ⁹ , and Z ¹ can be S (sulfur). In other embodiments, X ¹ can be O (oxygen), R ¹ can be -Z -R ⁹ , and Z ¹ can be N(R ¹⁰ ).

[0096] In some embodiments, X ¹ can be S (sulfur). In some embodiments, X ¹ can be S (sulfur), and R can be -Z -R ⁹ . In some embodiments, X can be S (sulfur), R can be -Z - R ⁹ , and Z ¹ can be O (oxygen). In other embodiments, X ¹ can be S (sulfur), R ¹ can be -Z ^x -R ⁹ , and Z ¹ can be S (sulfur). In other embodiments, X ¹ can be S (sulfur), R ¹ can be -Z'-R ⁹ , and Z ¹ can be N(R ¹⁰ ).

[0097] The substituents attached to the 5 '-position of a compound of Formula (I) can vary. In some embodiments, R ² and R ³ can be the same. In other embodiments, R ² and R ³ can be different. In some embodiments, at least one of R ² and R ³ can be hydrogen. In other embodiments, both R ² and R ³ can be hydrogen. In some embodiments, at least one of R ² and R ³ can be selected from of an optionally substituted Ci_6 alkyl, an optionally substituted C ₂ -6 alkenyl, an optionally substituted C2-6 alkynyl, an optionally substituted Ci_e haloalkyl and an optionally substituted aryl(Ci_6 alkyl), or R ² and R ³ can be taken together to form a group selected from an optionally substituted C ₃ _ ₆ cycloalkyl, an optionally substituted C ₃ _ ₆ cycloalkenyl, an optionally substituted C3_6 aryl and an optionally substituted C3-6 heteroaryl. In some embodiments, at least one of R ² and R ³ cannot be hydrogen. In some embodiments, at least one of R ² and R ³ can be an optionally substituted Ci_6-alkyl; and the other of R ² and R ³ can be hydrogen. Examples of suitable optionally substituted Ci_6 alkyls include optionally substituted variants of the following: methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, pentyl (branched and straight-chained), and hexyl (branched and straight-chained). In some embodiments, at least one of R ² and R ³ can be methyl, and the other of R ² and R ³ can be hydrogen. In other embodiments, at least one of R ² and R ³ can be an optionally substituted Ci_6- haloalkyl, and the other of R ² and R ³ can be hydrogen. One example of a suitable optionally substituted Ci_ ₆ -haloalkyl is CF ₃ . In some embodiments, when X ¹ is O (oxygen), and R ¹ is -O- R ⁹ or -N(R ¹⁰ )-R ⁹ , then at least one of R ² and R ³ can be selected from an optionally substituted Ci_6 alkyl, an optionally substituted C ₂ -6 alkenyl, an optionally substituted C ₂ _6 alkynyl, an optionally substituted Ci_6 haloalkyl and an optionally substituted aryl(Ci_e alkyl), or R ² and R ³ can be taken together to form a group selected from an optionally substituted C ₃ _6 cycloalkyl, an optionally substituted C ₃ _6 cycloalkenyl, an optionally substituted C ₃ _6 aryl and an optionally substituted C _ ₆ heteroaryl. In some embodiments, when X ¹ is O (oxygen), and R ¹ is -O-R ⁹ or - N(R ¹⁰ )-R ⁹ , then at least one of R ² and R ³ cannot be hydrogen. In some embodiments, R ³ , R ⁴ , R ⁵ and R ⁸ can each be hydrogen; and R ² can be an optionally substituted Ci_ ₆ alkyl. Suitable Ci_ ₆ alkyl groups are described herein. When the substituents attached to the 5 '-carbon make the 5 '- carbon chiral, in some embodiments, the 5 '-carbon can be a (R)-stereocenter. In other embodiments, the 5 '-carbon can be an (S)-stereocenter.

[0098] Various amino acids derivatives can be used, including those described herein. In some embodiments, R ¹ can be an optionally substituted N-linked a-amino acid. Suitable amino acids include, but are not limited to, alanine, asparagine, aspartate, cysteine, glutamate, glutamine, glycine, proline, serine, tyrosine, arginine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine. Additional suitable amino acids include, but are not limited to, alpha-ethyl-glycine, alpha-propyl-glycine and beta-alanine. In other embodiments, R ¹ can be an optionally substituted N-linked a-amino acid ester derivative. Various amino acid ester derivatives can be used, including those described herein. For example, R ¹ can be an ester derivative of any of the following amino acids: alanine, asparagine, aspartate, cysteine, glutamate, glutamine, glycine, proline, serine, tyrosine, arginine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine. Additional examples of N-linked amino acid ester derivatives include, but are not limited to, an ester derivative of any of the following amino acids: alpha-ethyl-glycine, alpha- propyl-glycine and beta-alanine.

[0099] In some embodiments, R ¹ can be an ester derivative of alanine. In some embodiments, R ¹ can be selected from alanine methyl ester, alanine ethyl ester, alanine isopropyl ester, alanine cyclohexyl ester, alanine neopentyl ester, valine isopropyl ester and leucine isopropyl ester. In some embodiments, the optionally substituted N-linked amino acid or the optionally substituted N-linked amino acid ester derivative can be in the L-configuration. In other embodiments, the optionally substituted N-linked amino acid or the optionally substituted N-linked amino acid ester derivative can be in the D-configuration.

[0100] In some embodiments, R can have the structure wherein

R can be selected from hydrogen, an optionally substituted C^-alkyl, an optionally substituted C -6 cycloalkyl, an optionally substituted aryl, an optionally substituted aryl(Ci_6 alkyl) and an optionally substituted Ci_6 haloalkyl; R ¹⁸ can be selected from hydrogen, an optionally substituted Ci_6 alkyl, an optionally substituted Ci_6 haloalkyl, an optionally substituted C ₃ -6 cycloalkyl, an optionally substituted C aryl, an optionally substituted C ₁₀ aryl and an optionally substituted aryl(Ci_6 alkyl); and R ¹⁹ can be hydrogen or an optionally substituted Ci_4-alkyl; or R ¹⁸ and R ¹⁹ can be taken together to form an optionally substituted C ₃ _6 cycloalkyl.

[0101] When R can be an optionally substituted Ci_6-alkyl. Examples of suitable optionally substituted Ci_6-alkyls include optionally substituted variants of the following: methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert- butyl, pentyl (branched and straight-chained), and hexyl (branched and straight-chained). When R ¹⁸ is substituted, R ¹⁸ can be substituted with one or more substituents selected from N-amido, mercapto, alkylthio, an optionally substituted aryl, hydroxy, an optionally substituted heteroaryl, O-carboxy, and amino. In some embodiments, R ¹⁸ can be an unsubstituted Ci_6-alkyl, such as those described herein. In some embodiments, R ¹⁸ can be methyl.

[0102] As to R ¹⁷ , in some embodiments, R ¹⁷ can be an optionally substituted Ci_6 alkyl. Examples of optionally substituted Ci_6-alkyls include optionally substituted variants of the following: methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, pentyl (branched and straight-chained), and hexyl (branched and straight-chained). In some embodiments, R ¹⁷ can be methyl or isopropyl. In some embodiments, R ¹⁷ can be ethyl or neopentyl. In other embodiments, R ¹⁷ can be an optionally substituted C ₃ _6 cycloalkyl. Examples of optionally substituted C3-6 cycloalkyl include optionally substituted variants of the following: cyclopropyl, cyclobutyl, cyclopentyl, and cyclohexyl. In some embodiments, R ¹⁷ can be an optionally substituted cyclohexyl. In still other embodiments, R ¹⁷ can be an optionally substituted aryl, such as phenyl and naphthyl. In yet still other embodiments, R ¹⁷ can be an optionally substituted aryl(Ci_6 alkyl). In some embodiments, R ¹⁷ can be an optionally substituted benzyl. In some embodiments, R ¹⁷ can be an optionally substituted Ci_6 haloalkyl, for example, CF ₃ .

[0103] In some embodiments, R ¹⁹ can be hydrogen. In other embodiments, R ¹⁹ can be an optionally substituted Ci_4-alkyl, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl and tert-butyl. In some embodiments, R ¹⁹ can be methyl. In some embodiments, R ¹⁸ can be hydrogen. In some embodiments, R ¹⁸ and R ¹⁹ can be taken together to form an optionally substituted C3_6 cycloalkyl. Examples of optionally substituted C ₃ -6 cycloalkyl include optionally substituted variants of the following: cyclopropyl, cyclobutyl, cyclopentyl, and cyclohexyl. Depending on the groups that are selected for R ¹⁸ and R ¹⁹ , the carbon to which R ¹⁸ and R ¹⁹ are attached may be a chiral center. In some embodiments, the carbon to which R ¹⁸ and R ¹⁹ are attached may be a (R)-chiral center. In other embodiments, the carbon to which R ¹⁸ and 1 ⁹ are attached may be a (S)-chiral center.

[0105] In some embodiments, R ⁴ can be halogen, azido, cyano, an optionally substituted C _1-6 alkyl, an optionally substituted C ₂ -6 alkenyl, an optionally substituted C2-6 alkynyl or an optionally substituted allenyl. In some embodiments, R ⁴ can be hydrogen. In other embodiments, R ⁴ can be azido. In other embodiments, R ⁴ can be cyano. In still other embodiments, R ⁴ can be an optionally substituted allenyl. In yet still other embodiments, R ⁴ can be a halogen. In some embodiments, R ⁴ can be fluoro. In other embodiments, R ⁴ can be optionally substituted Ci_ ₆ alkyl, such as those described herein. In still other embodiments, R ⁴ can be optionally substituted C2-6 alkenyl. In yet still other embodiments, R ⁴ can be optionally substituted C2-6 alkynyl.

[0106] Various substituents can be attached to the 3'-carbon. In some embodiments, R ⁵ can be hydrogen. In other embodiments, R ⁵ can be an optionally substituted Ci_6 alkyl. Examples of optionally substituted Ci_6-alkyls include optionally substituted variants of the following: methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, pentyl (branched and straight-chained), and hexyl (branched and straight-chained).

[0107] The substituents attached to the 2'-carbon can vary. In some embodiments, R ⁶ can be hydrogen. In some embodiments, R can be halogen, azido, amino, cyano, an optionally substituted Ci_6 alkyl, -OR ¹¹ or -OC(=0)R ¹² . In some embodiments, R ⁶ can be halogen. In other embodiments, R ⁶ can be azido. In still other embodiments, R ⁶ can be amino. In yet still other embodiments, R ⁶ can be cyano. In some embodiments, R ⁶ can be an optionally substituted Ci_6 alkyl. Examples of optionally substituted Ci_6 alkyl groups include, but are not limited to, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl and tert-butyl. In other embodiments, R ⁶ can be -OR ¹¹ . In some embodiments, when R ¹¹ is hydrogen, R ⁶ can be a hydroxy group. In other embodiments, when R ¹¹ is an optionally substituted Ci_6 alkyl, R ⁶ can be an optionally substituted Ci_6 alkoxy. Suitable optionally substituted Ci_6 alkoxy groups are described herein. In some embodiments, R can be -OC(=0)R ¹² , wherein R ¹² can be an optionally substituted Ci_6 alkyl, such as optionally substituted variants of the following: methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, pentyl (branched and straight- chained), and hexyl (branched and straight-chained). In other embodiments, R ⁶ can be - 0C(O)R ¹² , wherein R ¹² can be an optionally substituted C3_6 cycloalkyl.

[0108] In some embodiments, R ⁷ can be hydrogen. In some embodiments, R ⁷ can be halogen, azido, cyano, an optionally substituted Ci_ ₆ alkyl, -OR ¹³ or -OC(=0)R ¹⁴ . In some embodiments, R ⁷ can be halogen. In other embodiments, R ⁷ can be azido. In still other embodiments, R ⁷ can be cyano. In other embodiments, R ⁷ can be an optionally substituted Ci_6 alkyl. Examples of optionally substituted Ci_6 alkyl groups include, but are not limited to, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl and tert-butyl. In still other embodiments,

R 1 can be -OR 13. When R13 is hydrogen, R 7 can be hydroxy. Alternatively, when R 13 is an optionally substituted Ci_6 alkyl, R ⁷ can be an optionally substituted Ci_6 alkoxy. Suitable alkoxy groups include methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, tert- butoxy, pentoxy (branched and straight-chained), and hexoxy (branched and straight-chained). In some embodiments, R can be -OC(=0)R ¹⁴ in which R ¹⁴ is an optionally substituted Ci_6 alkyl or an optionally substituted C -6 cycloalkyl. Examples of suitable Ci_6 alkyl groups are described herein.

[0109] In some embodiments, at least one of R ⁶ and R ⁷ can be a halogen. In some embodiments, R ⁶ and R ⁷ can both be a halogen. In other embodiments, R ⁶ can be a halogen and R ⁷ can be an optionally substituted alkyl, such as those described herein. In still other embodiments, R ⁶ can be a hydroxy and R ⁷ can be an optionally substituted Ci_6 alkyl, such as those described herein.

[0110] In some embodiments, R ⁸ can be hydrogen. In some embodiments, R ⁸ can be halogen, azido, cyano, an optionally substituted Ci_6 alkyl, -OR ¹⁵ or -OC(=0)R ¹⁶ . In some embodiments, R ⁸ can be halogen. In other embodiments, R ⁸ can be azido. In still other embodiments, R ⁸ can be cyano. In other embodiments, R ⁸ can be an optionally substituted Ci_6 alkyl. Examples of optionally substituted Ci_6 alkyl groups include, but are not limited to, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl and tert-butyl. In still other embodiments,

8 can b 15 15 8 ternatively, when 15

R e -OR . When R is hydrogen, R can be hydroxy. Al R is an optionally substituted Ci_6 alkyl, R ⁸ can be an optionally substituted Ci_6 alkoxy. Suitable alkoxy groups include methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, tert- butoxy, pentoxy (branched and straight-chained), and hexoxy (branched and straight-chained). In some embodiments, R can be -OC(=0)R ¹⁶ in which R ¹⁶ is an optionally substituted Ci_6 alkyl or an optionally substituted C ₃ -6 cycloalkyl. Examples of suitable Ci_6 alkyl groups are described herein.

[0111] Those skilled in the art understand that when a hydrogen atom is removed or is absent from an oxygen atom, the oxygen atom can have a negative charge. For example, when R ⁵ is a hydroxy group and the hydrogen is removed or absent, the oxygen atom to which to hydrogen atom was associated with can be O ^" . Likewise, when R ⁷ or R ⁸ is a hydroxy group and the hydrogen is removed or is absent, the oxygen atom to which to hydrogen atom was associated with can be O ^" . In some embodiments, R ² , R ³ , R ⁴ , R ⁵ and R ⁸ can each be hydrogen.

[0112] When R ¹ is Z ^x -R ⁹ , the R ⁹ group can vary. In some embodiments, R ⁹ can be selected from an optionally substituted alkyl, an optionally substituted alkenyl, an optionally substituted alkynyl, an optionally substituted cycloalkyl, an optionally substituted cycloalkenyl, an optionally substituted aryl, an optionally substituted heteroaryl, an optionally substituted heterocyclyl, an optionally substituted aryl(Ci_6 alkyl), an optionally substituted heteroaryl(Ci_6 alkyl), an optionally substituted heterocyclyl(Ci_6 alkyl) and Formula (II). In other embodiments, R ⁹ can be selected from an optionally substituted alkynyl, an optionally substituted cycloalkyl, an optionally substituted cycloalkenyl, an optionally substituted heteroaryl, an optionally substituted heterocyclyl, an optionally substituted heteroaryl(Ci_6 alkyl) and an optionally substituted heterocyclyl(Ci_6 alkyl). In some embodiments, R ⁹ can be an optionally substituted alkyl. In some embodiments, R ⁹ can be an optionally substituted Ci_6 alkyl. Examples of optionally substituted Ci_<5 alkyl groups include, but are not limited to, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl and tert-butyl. In some embodiments, R ⁹ can be an optionally substituted aryl. In some embodiments, R ⁹ can be an optionally substituted phenyl. In some embodiments, R ⁹ can be an optionally substituted aryl(Ci_6 alkyl). In some embodiments, R ⁹ can be benzyl. In some embodiments, R ⁹ can be an optionally substituted cycloalkyl. In some embodiments, R ⁹ can be cyclobutyl, cyclopentyl, or cyclohexyl. In some embodiments, R ⁹ can be -CE -cyclopropyl. In some embodiments, R ¹⁰ can be hydrogen or an optionally substituted alkyl (for example, an optionally substituted Ci_6 alkyl).

[0113] In some embodiments, R ⁹ can be Formula (II). In some embodiments, R ²⁰ and 21 both can be hydrogen. In some embodiments, R 20 and R 21 can each be an optionally substituted Ci_24 alkyl or an optionally substituted aryl. In some embodiments, at least one of R ²⁰ and R ²¹ can an optionally substituted Ci_24 alkyl or an optionally substituted aryl, and the other of R 20 ^u and R 2 ^Z 1 ¹ can be hydrogen. In some embodiments, R 22 can be hydrogen. In some embodiments, R ²² can be an optionally substituted Q_ ₂ 4 alkyl. In some embodiments, R ²² can be an optionally substituted aryl. In some embodiments, R ²² can be an optionally substituted -O- Ci_24 alkyl. In some embodiments, R ²² can be an optionally substituted -0-Ci_g alkyl. Examples of optionally substituted Ci_6 alkyl groups include, but are not limited to, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, pentyl (branched and straight-chained), and hexyl (branched and straight-chained). In some embodiments, R ²² can be an optionally substituted -O-aryl. In some embodiments, Y ¹ can be O (oxygen). In some embodiments, Y ¹ can be S (sulfur). In some embodiments, R ⁹ can be Formula (II), R ²⁰ and R ²¹ both can be hydrogen, R ²² can be an optionally substituted Ci_ ₂ 4 alkyl, and Y ¹ can be O (oxygen). In other embodiments, R can be Formula (II), R and R both can be hydrogen, R can be an optionally substituted Ci_ ₂ 4 alkyl, and Y ¹ can be S (sulfur). In some embodiments, R ²⁰ and R ²¹ both can be hydrogen, R ²² can be tert-butyl, and Y ¹ can be O (oxygen). In other embodiments,

R 20 and R 21 both can be hydrogen, R 22 can be tert-butyl, and Y 1 can be S (sulfur). In some embodiments, R ⁹ can be pivaloyloxymethyl. In some embodiments, R ⁹ can be isopropyloxycarbonyloxymethyl.

[0114] In some embodiments, R ⁵ and R ⁸ can each be hydrogen; and R ⁴ can be azido. In other embodiments, R ⁴ , R ⁵ , R ⁷ and R ⁸ can each be hydrogen; and R ⁶ can be -OH. In still other embodiments, R ⁴ , R ⁵ and R ⁸ can each be hydrogen; and R ⁶ can be halogen. In yet still other embodiments, R ⁴ , R ⁵ and R ⁸ can each be hydrogen; and R ⁷ can be an optionally substituted Ci-6 alkyl. In some embodiments, R ⁴ , R ⁵ and R ⁸ can each be hydrogen; R ⁶ can be a halogen; and R ⁷ can be an optionally substituted Ci_6 alkyl. In other embodiments, R ⁴ , R ⁵ and R ⁸ can each be hydrogen; and R ⁷ can be methyl. In still other embodiments, R ⁴ , R ⁵ and R ⁸ can each be hydrogen; and R ⁷ can be halogen. In some embodiments, R ⁴ , R ⁵ and R ⁸ can each be hydrogen; R ⁶ can be a halogen; and R ⁷ can be a halogen. In yet still other embodiments, R ⁴ , R ⁵ and R ⁸ can each be hydrogen; R ⁶ can be -OR ¹¹ ; R ¹¹ can be hydrogen; and R ⁷ can be an optionally substituted Ci_6 alkyl. In some embodiments, R ⁴ , R ⁵ and R ⁸ can each be hydrogen; R ⁶ can be - OH; and R ⁷ can be methyl. In other embodiments, R ⁴ , R ⁵ and R ⁸ can each be hydrogen; R ⁶ can be -OR ¹¹ ; R ¹¹ can be hydrogen; and R ⁷ can be halogen. In some of the embodiments of this paragraph, R ² and R ³ can both be hydrogen. In some of the embodiments of this paragraph, at least one of R ² and R ³ can be an optionally substituted Ci_6 alkyl; and the other of R ² and R ³ can be hydrogen.

[0115] Various optionally substituted heterocyclic bases can be attached to the pentose ring. In some embodiments, one or more of the amine and/or amino groups may be protected with a suitable protecting group. For example, an amino group may be protected by transforming the amine and/or amino group to an amide or a carbamate. In some embodiments, B ¹ can be an optionally substituted heterocyclic base or an optionally substituted heterocyclic base with one or more protected amino groups can have one of the following structures:

wherein: R can be selected from hydrogen, halogen and NHR , wherein R can be selected from hydrogen, -C(=0)R ^K2 and -C(=0)OR ^L2 ; R ^B2 can be halogen or NHR ^W2 , wherein R ^W2 is selected from hydrogen, an optionally substituted Ci_6 alkyl, an optionally substituted C2-6 alkenyl, an optionally substituted C ₃ _ ₈ cycloalkyl, -C(=0)R ^M2 and -C(=0)OR ^N2 ; R ^C2 can be hydrogen or NHR ⁰² , wherein R ⁰² can be selected from hydrogen, -C(=0)R ^P2 and -C(=0)OR ^Q2 ;

_R D2 can be selected from hydrogen, halogen, an optionally substituted Ci_6 alkyl, an optionally substituted C2-6 alkenyl and an optionally substituted C2-6 alkynyl; R can be selected from hydrogen, an optionally substituted C _1-6 alkyl, an optionally substituted C3-8 cycloalkyl, -

R2 S2 F2

C(=0)R and -C(=0)OR ; R can be selected from hydrogen, halogen, an optionally substituted Ci_e alkyl, an optionally substituted C2-6 alkenyl and an optionally substituted C2-6 alkynyl; Y ² can be N (nitrogen) or CR ¹² , wherein R ¹² can be selected from hydrogen, halogen, an optionally substituted Ci_6-alkyl, an optionally substituted C2-6-alkenyl and an optionally substituted C ₂ -6-alkynyl; R ^G2 can be an optionally substituted Ci_6 alkyl; R ^H2 can be hydrogen or

T2 wherein T2 I J2

NHR , R ¹ can be independently selected from hydrogen, -C(=0)R and - C(=0)OR ^V2 , and R , R ^L2 , R ^M2 , R ^N2 , R ^P2 , R ^Q2 R ^R2 , R ^S2 , R ^U2 and R ^V2 can be independently selected from Ci_6 alkyl, C2-6 alkenyl, C2-6 alkynyl, C3-6 cycloalkyl, C3-6 cycloalkenyl, C3-6 cycloalkynyl, C6-10 aryl, heteroaryl, heterocyclyl, aryl(Ci_6 alkyl), heteroaryl(Ci_6 alkyl) and heterocyclyl(Ci_6 alkyl). In some embodiments, the structures shown above can be modified by replacing one or more hydrogens with substituents selected from the list of substituents provided for the definition of "substituted."

[0116] In some embodiments, B ¹ can be selected from adenine, guanine, thymine, cytosine and uracil. In some embodiments, B ¹ can be an optionally substituted

In still other embodiments, B ¹ can be

In yet still other embodiments, B ¹ can be an optionally substituted

In some embodiments R ^F2 can be hydrogen. In some embodiments, B ¹ can

some embodiments, B ¹ can be an optionally substituted bodiments, B ¹ can be

In other embodiments, B ¹ can be In yet still other

embodiments, B ¹ can be In some embodiments, B ¹ can be an optionally

For example, B can wherein R G2 can be an optionally substituted Ci_4 alkyl; and R ^H2 can be NH ₂ . In some embodiments, R ^uz can be methyl or ethyl.

[0117] In some embodiments, when X ¹ is S (sulfur), R ¹ is -Z -R ⁹ and Z ¹ is N(R ¹⁰ ), then B ¹ can be an optionally substituted cytosine or an optionally substituted uracil. In some embodiments, when X ¹ is O (oxygen), R ¹ is -Z^R ⁹ and Z ¹ is S (sulfur), then B ¹ can be an optionally substituted cytosine.

[0118] In some embodiments, if B ¹ is an optionally substituted guanine, then R ¹ can be an optionally substituted N-linked amino acid or an optionally substituted N-linked amino acid ester derivative. In other embodiments, if B ¹ is an optionally substituted guanine and R ¹ is -Z -R ⁹ , then R ⁹ can be a substituted alkyl, such as a substituted Ci_6 alkyl. In still other embodiments, if B is an optionally substituted guanine and R ¹ is -Z ^x -R ⁹ , then R ⁹ can be a substituted alkenyl. In yet still other embodiments, if B ¹ is an optionally substituted guanine and R ¹ is -Z -R ⁹ , then R ⁹ can be an unsubstituted aryl. In some embodiments, if B is an optionally substituted guanine and R ¹ is -Z ^x -R ⁹ , then R ⁹ can be Formula (II). In some embodiments, if B is an optionally substituted guanine and R ¹ is -Z -R ⁹ , then R ⁹ can be Formula (II), wherein R and R ²¹ both can be hydrogen, R ²² can be an optionally substituted Ci_24 alkyl, and Y ¹ can be O (oxygen) or S (sulfur). In some embodiments, if B ¹ is an optionally substituted guanine and R ¹ is -Z^R ⁹ , then R ⁹ can be pivaloyloxymethyl. In some embodiments, if B ¹ is an optionally substituted guanine and R ¹ is -Z ^x -R ⁹ , then R ⁹ can be isopropyloxycarbonyloxymethyl. In some of the embodiments of this paragraph, the optionally substituted guanine can be a protected guanine. In some of the embodiments of this paragraph, X ¹ is S (sulfur). In some of the embodiments of this paragraph, X ¹ is O (oxygen).

[0119] In some embodiments, if B ¹ is an optionally substituted uracil, then R ¹ can be an optionally substituted N-linked amino acid or an optionally substituted N-linked amino acid ester derivative. In other embodiments, if B ¹ is an optionally substituted uracil and R ¹ is -Z ¹ - R ⁹ , then R ⁹ can be a substituted alkyl. In still embodiments, if B is an optionally substituted uracil and R ¹ is -Z -R ⁹ , then R ⁹ can be an unsubstituted aryl. In some embodiments, if B is an optionally substituted uracil and R ¹ is -Z ^x -R ⁹ , then R ⁹ can be Formula (II). In some embodiments, if B ¹ is an optionally substituted uracil and R ¹ is -Z ^x -R ⁹ , then R ⁹ can be Formula

(II), wherein R 20 and R 21 both can be hydrogen, R 22 can be an optionally substituted Ci_ ₂₄ alkyl, and Y ¹ can be O (oxygen) or S (sulfur). In some embodiments, if B ¹ is an optionally substituted uracil and R ¹ is -Z -R ⁹ , then R ⁹ can be pivaloyloxymethyl. In some embodiments, if B is an optionally substituted uracil and R ¹ is -Z ^x -R ⁹ , then R ⁹ can be isopropyloxycarbonyloxymethyl. In some of the embodiments of this paragraph, the optionally substituted uracil can be a protected uracil. In some of the embodiments of this paragraph, X ¹ is S (sulfur). In some of the embodiments of this paragraph, X ¹ is O (oxygen).

[0120] In some embodiments, if B ¹ is an optionally substituted thymine, then R ¹ can be an optionally substituted N-linked amino acid or an optionally substituted N-linked amino acid ester derivative. In other embodiments, if B ¹ is an optionally substituted thymine and R ¹ is -Z -R ⁹ , then R ⁹ can be a substituted alkyl. In still other embodiments, if B is an optionally substituted thymine and R ¹ is -Z ^x -R ⁹ , then R ⁹ can be a substituted alkenyl. In yet still other embodiments, if B ¹ is an optionally substituted thymine and R ¹ is Z ¹ R ⁹ , then R ⁹ can be a substituted aryl. In some embodiments, if B ¹ is an optionally substituted thymine and R ¹ is -Z ¹ - R ⁹ , then R ⁹ can be Formula (II). In some embodiments, if B is an optionally substituted thymine and R ¹ is -Z'-R ⁹ , then R ⁹ can be Formula (II), wherein R ²⁰ and R ²¹ both can be hydrogen, R ²² can be an optionally substituted C _1-24 alkyl, and Y ¹ can be O (oxygen) or S (sulfur). In some embodiments, if B ¹ is an optionally substituted thymine and R ¹ is -Z ^x -R ⁹ , then R ⁹ can be pivaloyloxymethyl. In some embodiments, if B is an optionally substituted thymine and R ¹ is -Z^R ⁹ , then R ⁹ can be isopropyloxycarbonyloxymethyl. In some of the embodiments of this paragraph, the optionally substituted thymine can be a protected thymine. In some of the embodiments of this paragraph, X ¹ is S (sulfur). In some of the embodiments of this paragraph, X ¹ is O (oxygen).

[0121] In some embodiments, if B ¹ is an optionally substituted adenine, then R ¹ can be an optionally substituted N-linked amino acid or an optionally substituted N-linked amino acid ester derivative. In other embodiments, if B ¹ is an optionally substituted adenine and R ¹ is -Z -R ⁹ , then R ⁹ can be a substituted alkyl. In still other embodiments, if B is an optionally substituted adenine and R ¹ is -Z^R ⁹ , then R ⁹ can be a substituted alkenyl. In some embodiments, if B ¹ is an optionally substituted adenine and R ¹ is -Z^R ⁹ , then R ⁹ can be Formula (II). In some embodiments, if B ¹ is an optionally substituted adenine and R ¹ is -Z ^x -R ⁹ , then 9 wherein 20 21 22

R can be Formula (II), R and R both can be hydrogen, R can be an optionally substituted Ci_24 alkyl, and Y ¹ can be O (oxygen) or S (sulfur). In some embodiments, if B ¹ is an optionally substituted adenine and R ¹ is -Z ^L -R ⁹ , then R ⁹ can be pivaloyloxymethyl. In some embodiments, if B ¹ is an optionally substituted adenine and R ¹ is -Z^R ⁹ , then R ⁹ can be isopropyloxycarbonyloxymethyl. In some of the embodiments of this paragraph, the optionally substituted adenine can be a protected adenine. In some of the embodiments of this paragraph, X ¹ is S (sulfur). In some of the embodiments of this paragraph, X ¹ is O (oxygen).

[0122] In some embodiments, if B ¹ is an optionally substituted cytosine, then R ¹ can be an optionally substituted N-linked amino acid or an optionally substituted N-linked amino acid ester derivative. In other embodiments, if B ¹ is an optionally substituted cytosine and R ¹ is -Z -R ⁹ , then R ⁹ can be a substituted alkyl. In still other embodiments, if B is an optionally substituted cytosine and R ¹ is -Z'-R ⁹ , then R ⁹ can be a substituted alkenyl. In yet still other embodiments, if B ¹ is an optionally substituted cytosine and R ¹ is -Z ^x -R ⁹ , then R ⁹ can be a substituted aryl. In some embodiments, if B ¹ is an optionally substituted cytosine and R ¹ is -Z ¹ - R ⁹ , then R ⁹ can be Formula (II). In some embodiments, if B is an optionally substituted cytosine and R ¹ is -Z ^J -R ⁹ , then R ⁹ can be Formula (II), wherein R ²⁰ and R ²¹ both can be hydrogen, R ²² can be an optionally substituted C _1-24 alkyl, and Y ¹ can be O (oxygen) or S (sulfur). In some embodiments, if B ¹ is an optionally substituted cytosine and R ¹ is -Z ^x -R ⁹ , then R ⁹ can be pivaloyloxymethyl. In some embodiments, if B is an optionally substituted cytosine and R ¹ is -Z ^x -R ⁹ , then R ⁹ can be isopropyloxycarbonyloxymethyl. In some of the embodiments of this paragraph, the optionally substituted cytosine can be a protected cytosine. In some of the embodiments of this paragraph, X ¹ is S (sulfur). In some of the embodiments of this paragraph, X ¹ is O (oxygen). [0123] In some embodiments, R ⁴ cannot be hydrogen. In some embodiments, R ⁵ cannot be hydrogen. In some embodiments, R ⁶ cannot be hydrogen. In some embodiments, R ⁶ cannot be a hydroxy group. In other embodiments, when R is -OC(=0)R , then R cannot be -CH-(CH ₃ ) ₂ . In still other embodiments, when R ⁶ is -OC(=0)R ¹² , then R ¹² cannot be an optionally substituted alkyl, for example, a substituted C _1-4 alkyl or an unsubstituted Ci_ ₄ alkyl. In some embodiments, R ⁷ cannot be hydrogen. In some embodiments, R ⁸ cannot be hydrogen. In some embodiments, R ⁹ cannot be an optionally substituted alkyl, such as a substituted or unsubstituted C _1-4 alkyl. In other embodiments, R ⁹ cannot be an optionally substituted alkenyl, for example -CH ₂ CH=CH ₂ . In still other embodiments, R ⁹ cannot be an optionally substituted aryl, such as an optionally substituted phenyl. In yet still other embodiments, R ⁹ cannot be an optionally substituted aryl(Ci_ ₆ alkyl), such as an optionally substituted benzyl. In some embodiments, R ⁹ cannot be -CH ₂ -OC(=0)CH ₃ , -CH ₂ -OC(=0)-t-butyl,

alkyl), -CH ₂ -OC(=0)-0-isopropyl, or -CH ₂ -OC(=0)-0-(Ci_ ₆ alkyl). In some embodiments,

B cannot be an optionally In

some embodiments, B ¹ can not be an optionally substituted . In some

embodiments, B cannot be an optionally substituted such as

some embodiments, B ¹ cannot be an optionally substituted . In some embodiments, B ¹ cannot be a dimethylformamide protected guanine or a 2-(nitrophenyl)ethyl protected guanine. In other embodiments, B ¹ cannot be an acyl protected guanine. In still other embodiments, B ¹ cannot be a 2-(nitrophenyl)ethyl protected uracil. In some embodiments, B ¹ cannot be a 2-(nitrophenyl)sulfonylethyl protected uracil. In yet still other embodiments, B ¹ cannot be a benzoyl protected adenine. In some embodiments, B ¹ cannot be an anisoyl protected cytosine. In some embodiments, if B ¹ is an optionally substituted guanine and R ¹ is -Z ^x -R ⁹ , then R ⁹ cannot be methyl, -CH ₂ CH=CH ₂ , 2- chlorophenyl or -CH ₂ -C(=0)-C(=0)-CH ₂ -halo, such as -CH ₂ -C(=0)-C(=0)-CH ₂ Br, -CH ₂ - C(O)-C(=0)-CH ₂ Cl, -CH ₂ -C(O)-C(=0)-CH ₂ F, or -CH ₂ -C(=0)-C(=0)-CH ₂ I. In some embodiments, if B ¹ is an optionally substituted uracil and R ¹ is -Z^R ⁹ , then R ⁹ cannot be methyl or 2-chlorophenyl. In some embodiments, if B ¹ is an optionally substituted thymine and R ¹ is -Z'-R ⁹ , then R ⁹ cannot be methyl or -CH ₂ CH=CH ₂ . In other embodiments, if B ¹ is an optionally substituted thymine and R ¹ is Z ¹ R ⁹ , then R ⁹ cannot be an optionally substituted phenyl. In yet still other embodiments, if B ¹ is an optionally substituted adenine and R ¹ is -Z ¹ - R ⁹ , then R ⁹ cannot be methyl or ethyl. In some embodiments, if B ¹ is an optionally substituted adenine and R ¹ is -Z'-R ⁹ , then R ⁹ cannot be -CH ₂ CH=CH ₂ . In other embodiments, if B ¹ is an optionally substituted adenine and R ¹ is -Z ^l -R ⁹ , then R ⁹ cannot be phenyl. In some embodiments, if B ¹ is an optionally substituted adenine and R ¹ is -Z ^x -R ⁹ , then R ⁹ cannot be 2- chlorophenyl, 4-nitro-benzyl or 4-isobutyryloxy-benzyl. In other embodiments, if B ¹ is an optionally substituted adenine and R ¹ is -Z'-R ⁹ , then R ⁹ cannot be -CH ₂ -C(=0)-C(=0)-CH ₂ - halo, such as -CH ₂ -C(=0)-C(=0)-CH ₂ Br, -CH ₂ -C(=0)-C(=0)-CH ₂ C1, -CH ₂ -C(=0)-C(=0)- CH ₂ F, or -CH ₂ -C(=0)-C(=0)-CH ₂ I. In other embodiments, if B ¹ is an optionally substituted adenine and R ¹ is -Z -R ⁹ , then R ⁹ cannot be -CH ₂ -OC(=0)CH ₃ , -CH ₂ -OC(=0)C(CH ₃ ) ₃ , - CH ₂ -OC(=0)(Ci_6 alkyl), -CH ₂ -OC(=0)-0-isopropyl, or -CH ₂ -OC(=0)-0-(Ci_ ₆ alkyl).

[0124] Depending upon the substituents attached to the phosphorus atom, the phosphorus atom can be a chiral center. In some embodiments, the phosphorus can be a (R)- stereocenter. In other embodiments, the phosphorus can be a (S)-stereocenter.

[0125] In some embodiments, a compound of Formula (I) can be a single diastereomer. In other embodiments, a compound of Formula (I) can be a mixture of diastereomers. In some embodiments, a compound of Formula (I) can be a 1 : 1 mixture of two diastereomers. In some embodiments, a compound of Formula (I) can be diasteriometrically enriched (for example, one diastereomer can be present at a concentration of > 55%, > 75%, > 80%, > 90%, > 95%, > 98%, or > 99% as compared to the total concentration of the other diastereomers).

[0126] Some embodiments of R ¹ of a compound of Formula (I), or a pharmaceutically acceptable salt thereof, are provided in Table 1. Tables 2-3 provide the structures of the variables aaOl-aal 1 and es01-esl4, respectively. For example, the first entry in

"aa01,es01," which corresponds to a compound of Formula (I), wherein R ¹ is

Table 1

Table 2

aa04

aa07 aalO

Table 3

[0127] Examples of compounds of Formula (I) include, but are not limited to the following:

Synthesis

[0128] Compounds of Formula (I), and those described herein may be prepared in various ways. General synthetic routes to the compound of Formula (I), and some examples of starting materials used to synthesize the compounds of Formula (I) are shown in Schemes 1 and 2, and described herein. The routes shown and described herein are illustrative only and are not intended, nor are they to be construed, to limit the scope of the claims in any manner whatsoever. Those skilled in the art will be able to recognize modifications of the disclosed syntheses and to devise alternate routes based on the disclosures herein; all such modifications and alternate routes are within the scope of the claims. Scheme 1 :

(A) (I)

[0129] One method for forming a compound of Formula (I) is shown in Scheme 1. In Scheme 1 , R ^1A , R ^2A , R ^A , R ^4A , R ^5A , R ^6A , R ^7A , R ^8A , X ^1A and B ^1A can be the same as R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , X ¹ and B ¹ as described herein for Formula (I); and each LG can be a leaving group, such as a halogen or a sulfonate ester. As shown in Scheme 1, a nucleoside with a hydroxy group attached to the 3 '-carbon and a hydroxy group attached to 5 '-carbon can be reacted with a compound having the formula, R ^1A P(=X ^1A )(LG) ₂ , in the presence of a base, to produce a compound of Formula (I). Suitable bases are known to those skilled in the art. For example, the base can be an amine base, such as an alkylamine (including mono-, di- and tri- alkylamines (e.g., triethylamine)), optionally substituted pyridines (e.g., collidine) and optionally substituted imidazoles (e.g., N-methylimidazole)).

Scheme 2:

[0130] Another method for forming a compound of Formula (I) is shown in Scheme 2. In Scheme 2, R ^1A , R ^2A , R ^3A , R ^4A , R ^5A , R ^6A , R ^7A , R ^8A , X ^1A and B ^1A can be the same as R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , X ¹ and B ¹ as described herein for Formula (I); and each LG can be a leaving group, such as a halogen or a sulfonate ester. As illustrated in Scheme 2, a compound having a hydroxy group attached to the 3 '-carbon and a hydroxy group attached to the 5 '-carbon can be reacted with a compound having the formula, R ^1A P(LG)2, in the presence of a base, to produce a phosphite compound. Suitable bases are known to those skilled in the art and described herein. The phosphorus can then be oxidized to phosphorus(V) using a suitable oxidizing agent, to produce a compound of Formula (I) where X ¹ is O (oxygen). Alternatively, the phosphite compound can be reacted with a sulfurization reagent to produce a compound of Formula (I) where X ¹ is S (sulfur). Suitable oxidizing and sulfurization agents are known to those skilled in the art. For example, the oxidation can be carried out using iodine as the oxidizing agent and water as the oxygen donor. Suitable sulfurization agents include, but are not limited to, elemental sulfur, Lawesson's reagent, cyclooctasulfur, 3H-l ,2-Benzodithiole-3- one- 1 , 1 -dioxide (Beaucage's reagent), 3-((N,N-dimethylaminomethylidene)amino)-3H- 1 ,2,4- dithiazole-5-thione (DDTT) and bis(3-triethoxysilyl)propyl-tetrasulfide (TEST).

[0131] Any -NH, NH ₂ and/or keto groups present on B ^1A , for example, when B ^1A is an optionally substituted heterocyclic base, can be protected with one or more suitable protecting groups. Examples of suitable protecting groups include triarylmethyl groups, (2- nitrophenyl)ethyl groups, acyl groups, and dialkylformamidine groups. To reduce the formation of side products, one or more the groups attached to the pentose ring can be protected with one or more suitable protecting groups. As an example, if R ^4A , R ^5A , R ^6A , R ^7A and/or R ^8A is/are hydroxy group(s), the hydroxy group(s) can be protected with suitable protecting groups, such as triarylmethyl and/or silyl groups. Examples of triarylmethyl groups include but are not limited to, trityl, monomethoxytrityl (MMTr), 4,4'-dimethoxytrityl (DMTr), 4,4',4"- trimethoxytrityl (TMTr), 4,4',4"-tris- (benzoyloxy) trityl (TBTr), 4,4',4"-tris (4,5- dichlorophthalimido) trityl (CPTr), 4,4',4"-tris (levulinyloxy) trityl (TLTr), p-anisyl-1- naphthylphenylmethyl, di-o-anisyl- 1 -naphthylmethyl, p-tolyldipheylmethyl, 3- (imidazolylmethyl)-4,4'-dimethoxytrityl, 9-phenylxanthen-9-yl (Pixyl), 9-(p-methoxyphenyl) xanthen-9-yl (Mox), 4-decyloxytrityl, 4- hexadecyloxytrityl, 4,4'-dioctadecyltrityl, 9-(4- octadecyloxyphenyl) xanthen-9-yl, 1 , l'-bis-(4-methoxyphenyl)- -pyrenylmethyl, 4,4',4"-tris- (tert-butylphenyl) methyl (TTTr) and 4,4'-di-3, 5-hexadienoxytrityl. Examples of silyl groups include, but are not limited to, trimethylsilyl (TMS), feri-butyldimethylsilyl (TBDMS), triisopropylsilyl (TIPS), tert-butyldiphenylsilyl (TBDPS), tri-zso-propylsilyloxymethyl and [2- (trimethylsilyl)ethoxy]methyl. Alternatively, at least two of R ^4A , R ^5A , R ^6A , R ^7A and R ^8A can be protected by a single achiral or chiral protecting group, for example, by forming an orthoester, a cyclic acetal or a cyclic ketal. Suitable orthoesters include methoxymethylene acetal, ethoxymethylene acetal, 2-oxacyclopentylidene orthoester, dimethoxymethylene orthoester, 1- methoxyethylidene orthoester, 1 -ethoxyethylidene orthoester, methylidene orthoester, phthalide orthoester 1,2-dimethoxyethylidene orthoester, and alpha-methoxybenzylidene orthoester; suitable cyclic acetals include methylene acetal, ethylidene acetal, t-butylmethylidene acetal, 3- (benzyloxy)propyl acetal, benzylidene acetal, 3,4-dimethoxybenzylidene acetal and p- acetoxybenzylidene acetal; and suitable cyclic ketals include 1 -t-butylethylidene ketal, 1- phenylethylidene ketal, isopropylidene ketal, cyclopentylidene ketal, cyclohexylidene ketal, cycloheptylidene ketal and 1 -(4-methoxyphenyl)ethylidene ketal.

[0132] The chirality of the 5'-carbon of compounds of Formulae (A) and/or (I) can be inverted using methods known to the skilled in the art. For example, the oxygen attached to the 5 '-carbon can be oxidized, for example to an aldehyde for a compound of Formula (A) or ketone for a compound of Formula (I), using a suitable oxidizing agent. The aldehyde and/or ketone can then be reduced using a suitable reducing agent. Examples of suitable reducing agents include, but are not limited to, NaH, LiH, NaBH ₄ , LiAlH ₄ and CaH ₂ . Suitable oxidizing and reducing agents are known to those skilled in the art. Examples of suitable oxidizing agents and conditions are described herein.

[0133] In some embodiments, R ⁶ , R ⁷ and/or R ⁸ can be -OC(=0)R ⁿ , -OC(=0)R ¹³ , and -OC(=0)R ¹⁵ , respectively. The -OC(=0)R ⁿ , -OC(=0)R ¹³ , and -OC(=0)R ¹⁵ groups can be formed at the 1 ' and 2 '-positions using various methods known to those skilled in the art. As an example, a compound of Formula (I), wherein R ⁶ and R ⁸ are both hydroxy groups, can be treated with an alkyl anhydride (e.g., acetic anhydride and propionic anhydride) or an alkyl acid chloride (e.g., acetochloride). If desired, a catalyst can be used to facilitate the reaction. An example of suitable catalyst is 4-dimethylaminopyridine (DMAP). Alternatively, the - OC(=0)R ⁿ and -OC(=0)R ¹⁵ groups can be formed at the and 2'-positions by reacting an alkyl acid (e.g., acetic acid and propionic acid) in the presences of a carbodiimide or a coupling reagent. Examples of carbodiimides include, but are not limited to, Ν,Ν'- dicyclohexylcarbodiimide (DCC), Ν,Ν'-diisopropylcarbodiimide (DIC) and l-ethyl-3-(3- dimethylaminopropyl) carbodiimide (EDC).

[0134] As described herein, B ^1A can include a carbamate and/or an amide. Those skilled in the art know methods for forming a carbamate and/or an amide on B ^1A . In some embodiments, the carbamate can be formed using 1 , 1 '-carbonyldiimidazole and an alcohol.

[0135] During the synthesis of any of the compounds described herein, if desired, any hydroxy groups attached to the pentose ring, and any -NH, NH2 and/or keto groups present on the B ^1A can be protected with one or more suitable protecting groups. Suitable protecting groups are described herein. Those skilled in the art will appreciate that groups attached to the pentose ring and any -NH, NH ₂ and/or keto groups present on the B ^1A can be protected with various protecting groups, and any protecting groups present can be exchanged for other protecting groups. The selection and exchange of the protecting groups is within the skill of those of ordinary skill in the art. Any protecting group(s) can also be removed by methods known in the art, for example, with an acid (e.g., a mineral or an organic acid), a base or a fluoride source.

[0136] In some embodiments, neutralizing the charge on the phosphate group may facilitate the penetration of the cell membrane by a compound of Formula (I), or a pharmaceutically acceptable salt thereof, by making the compound more lipophilic compared to a nucleotide having a comparable structure with one or more charges present on the phosphate. Once absorbed and taken inside the cell, the groups attached to the phosphate can be easily removed by esterases, proteases or other enzymes. In some embodiments, the groups attached to the phosphate can be removed by simple hydrolysis. Inside the cell, the monophosphate or mono-thiophosphate thus released may then be metabolized by cellular enzymes to the diphosphate or the active triphosphate, or the a-thiodiphosphate or the active a- thiotriphosphate, respectively. Furthermore, in some embodiments, varying the substituents on a cyclic nucleotide analog compound described herein, such as compound of Formula (I), can help maintain the efficacy of such compounds by reducing undesirable effects, such as isomerization.

[0137] In some embodiments, a compound of Formula (I), or a pharmaceutically acceptable salt thereof, can act as a chain terminator of HCV replication. For example, incorporation of a compound of Formula (I) containing a moiety at the 2 '-carbon position can terminate further elongation of the RNA chain of HCV. For example, a compound of Formula (I) can contain a 2 '-carbon modification wherein R ⁷ is a non-hydrogen group selected from halogen or an optionally substituted Ci_6 alkyl.

[0138] In some embodiments, a compound of Formula (I), or a pharmaceutically acceptable salt thereof, can have increased metabolic and/or plasma stability. In some embodiments, a compound of Formula (I), or a pharmaceutically acceptable salt thereof, can be more resistant to hydrolysis and/or more resistant to enzymatic transformations. In some embodiments, a compound of Formula (I), or a pharmaceutically acceptable salt thereof, can have improved properties. A non- limiting list of example properties include, but are not limited to, increased biological half life, increased bioavailability, increase potency, a sustained in vivo response, increased dosing intervals, decreased dosing amounts, decreased cytotoxicity, reduction in required amounts for treating disease conditions, reduction in viral load, reduction in time to seroconversion (i.e., the virus becomes undetectable in patient serum), increased sustained viral response, a reduction of morbidity or mortality in clinical outcomes, increased subject compliance, decreased liver conditions (such as liver fibrosis, liver cirrohis and/or liver cancer), and compatibility with other medications. In some embodiments, a compound of Formula (I), or a pharmaceutically acceptable salt thereof, can have more potent antiviral activity (for example, a lower IC50 in an HCV replicon assay) as compared to the current standard of care.

[0139] Additionally, in some embodiments, the presence of a phosphorothioate, phosphoramidate or phosphorothioamidate in a compound of Formula (I) can increase the stability of the compound by inhibiting its degradation. Also, in some embodiments, the presence of a phosphorothioate, phosphoramidate or phosphorothioamidate can make the compound more resistant to cleavage in vivo and provide sustained, extended efficacy. In some embodiments, a phosphorothioate, phosphoramidate or phosphorothioamidate can facilitate the penetration of the cell membrane by a compound of Formula (I) by making the compound more lipophilic.

Pharmaceutical Compositions

[0140] Some embodiments described herein relates to a pharmaceutical composition, that can include a therapeutically effective amount of one or more compounds described herein (e.g., a compound of Formula (I), or a pharmaceutically acceptable salt thereof) and a pharmaceutically acceptable carrier, diluent, excipient or combination thereof. In some embodiments, the pharmaceutical composition can include a single diastereomer of a compound of Formula (I), or a pharmaceutically acceptable salt thereof, (for example, a single diastereomer is present in the pharmaceutical composition at a concentration of greater than 99% compared to the total concentration of the other diastereomers). In other embodiments, the pharmaceutical composition can include a mixture of diastereomers of a compound of Formula (I), or a pharmaceutically acceptable salt thereof. For example, the pharmaceutical composition can include a concentration of one diastereomer of > 50%, > 60%, > 70%, > 80%, > 90%, > 95%, or > 98%o, as compared to the total concentration of the other diastereomers. In some embodiments, the pharmaceutical composition includes a 1 : 1 mixture of two diastereomers of a compound of Formula (I), or a pharmaceutically acceptable salt thereof.

[0141] The term "pharmaceutical composition" refers to a mixture of one or more compounds disclosed herein with other chemical components, such as diluents or carriers. The pharmaceutical composition facilitates administration of the compound to an organism. Pharmaceutical compositions can also be obtained by reacting compounds with inorganic or organic acids such as hydrochloric acid, hydrobromic acid, sulfuric acid, nitric acid, phosphoric acid, methanesulfonic acid, ethanesulfonic acid, p-toluenesulfonic acid, and salicylic acid. Pharmaceutical compositions will generally be tailored to the specific intended route of administration.

[0142] The term "physiologically acceptable" defines a carrier, diluent or excipient that does not abrogate the biological activity and properties of the compound.

[0143] As used herein, a "carrier" refers to a compound that facilitates the incorporation of a compound into cells or tissues. For example, without limitation, dimethyl sulfoxide (DMSO) is a commonly utilized carrier that facilitates the uptake of many organic compounds into cells or tissues of a subject.

[0144] As used herein, a "diluent" refers to an ingredient in a pharmaceutical composition that lacks pharmacological activity but may be pharmaceutically necessary or desirable. For example, a diluent may be used to increase the bulk of a potent drug whose mass is too small for manufacture and/or administration. It may also be a liquid for the dissolution of a drug to be administered by injection, ingestion or inhalation. A common form of diluent in the art is a buffered aqueous solution such as, without limitation, phosphate buffered saline that mimics the composition of human blood.

[0145] As used herein, an "excipient" refers to an inert substance that is added to a pharmaceutical composition to provide, without limitation, bulk, consistency, stability, binding ability, lubrication, disintegrating ability etc., to the composition. A "diluent" is a type of excipient.

[0146] The pharmaceutical compositions described herein can be administered to a human patient per se, or in pharmaceutical compositions where they are mixed with other active ingredients, as in combination therapy, or carriers, diluents, excipients or combinations thereof. Proper formulation is dependent upon the route of administration chosen. Techniques for formulation and administration of the compounds described herein are known to those skilled in the art.

[0147] The pharmaceutical compositions disclosed herein may be manufactured in a manner that is itself known, e.g. , by means of conventional mixing, dissolving, granulating, dragee-making, levigating, emulsifying, encapsulating, entrapping or tableting processes. Additionally, the active ingredients are contained in an amount effective to achieve its intended purpose. Many of the compounds used in the pharmaceutical combinations disclosed herein may be provided as salts with pharmaceutically compatible counterions.

[0148] Multiple techniques of administering a compound exist in the art including, but not limited to, oral, rectal, topical, aerosol, injection and parenteral delivery, including intramuscular, subcutaneous, intravenous, intramedullary injections, intrathecal, direct intraventricular, intraperitoneal, intranasal and intraocular injections.

[0149] One may also administer the compound in a local rather than systemic manner, for example, via injection of the compound directly into the infected area, often in a depot or sustained release formulation. Furthermore, one may administer the compound in a targeted drug delivery system, for example, in a liposome coated with a tissue-specific antibody. The liposomes will be targeted to and taken up selectively by the organ.

[0150] The compositions may, if desired, be presented in a pack or dispenser device which may contain one or more unit dosage forms containing the active ingredient. The pack may for example comprise metal or plastic foil, such as a blister pack. The pack or dispenser device may be accompanied by instructions for administration. The pack or dispenser may also be accompanied with a notice associated with the container in form prescribed by a governmental agency regulating the manufacture, use, or sale of pharmaceuticals, which notice is reflective of approval by the agency of the form of the drug for human or veterinary administration. Such notice, for example, may be the labeling approved by the U.S. Food and Drug Administration for prescription drugs, or the approved product insert. Compositions that can include a compound described herein formulated in a compatible pharmaceutical carrier may also be prepared, placed in an appropriate container, and labeled for treatment of an indicated condition.

Methods of Use

[0151] Some embodiments disclosed herein relate to a method of treating and/or ameliorating a disease or condition that can include administering to a subject a therapeutically effective amount of one or more compounds described herein, such as a compound of Formula (I), or a pharmaceutically acceptable salt thereof, or a pharmaceutical composition that includes a compound described herein, or a pharmaceutically acceptable salt thereof.

[0152] Some embodiments disclosed herein relate to a method of ameliorating or treating a neoplastic disease that can include administering to a subject suffering from a neoplastic disease a therapeutically effective amount of one or more compounds described herein (e.g., a compound of Formula (I), or a pharmaceutically acceptable salt thereof), or a pharmaceutical composition that includes a compound described herein, or a pharmaceutically acceptable salt thereof. In some embodiments, the neoplastic disease can be cancer. In some embodiments, the neoplastic disease can be a tumor such as a solid tumor. In some embodiments, the neoplastic disease can be leukemia. Exemplary leukemias include, but are not limited to, acute lymphoblastic leukemia (ALL), acute myeloid leukemia (AML) and juvenile myelomonocytic leukemia (JMML).

[0153] Some embodiments disclosed herein relate to a method of inhibiting the growth of a tumor that can include administering to a subject having a tumor a therapeutically effective amount of one or more compounds described herein (for example, a compound of Formula (I)), or a pharmaceutical composition that includes one or more compounds described herein, or a pharmaceutically acceptable salt thereof.

[0154] Other embodiments disclosed herein relates to a method of ameliorating or treating a viral infection that can include administering to a subject suffering from a viral infection a therapeutically effective amount of one or more compounds described herein (for example, a compound of Formula (I)), or a pharmaceutical composition that includes one or more compounds described herein, or a pharmaceutically acceptable salt thereof. In some embodiments, the viral infection can be caused by a virus selected from an adenovirus, an Alphaviridae, an Arbovirus, an Astrovirus, a Bunyaviridae, a Coronaviridae, a Filoviridae, a Flaviviridae, a Hepadnaviridae, a Herpesviridae, an Alphaherpesvirinae, a Betaherpesvirinae, a Gammaherpesvirinae, a Norwalk Virus, an Astroviridae, a Caliciviridae, an Orthomyxoviridae, a Paramyxoviridae, a Paramyxoviruses, a Rubulavirus, a Morbillivirus, a Papovaviridae, a Parvoviridae, a Picornaviridae, an Aphthoviridae, a Cardioviridae, an Enteroviridae, a Coxsackie virus, a Polio Virus, a Pvhinoviridae, a Phycodnaviridae, a Poxviridae, a Reoviridae, a Rotavirus, a Retroviridae, an A-Type Retrovirus, an Immunodeficiency Virus, a Leukemia Viruses, an Avian Sarcoma Viruses, a Rhabdoviruses, a Rubiviridae, a Togaviridae an Arenaviridae and/or a Bornaviridae. In some embodiments, the viral infection can be a hepatitis C viral (HCV) infection. In other embodiments, the viral infection can be influenza. In still other embodiments, the viral infection can be HIV.

[0155] Some embodiments disclosed herein relate to methods of ameliorating and/or treating a viral infection that can include contacting a cell infected with the virus with an effective amount of one or more compounds described herein, or a pharmaceutically acceptable salt of a compound described herein, or a pharmaceutical composition that includes one or more compounds described herein, or a pharmaceutically acceptable salt thereof. Other embodiments described herein relate to using one or more compounds described herein, or a pharmaceutically acceptable salt of a compound described herein, in the manufacture of a medicament for ameliorating and/or treating a viral infection that can include contacting a cell infected with the virus with an effective amount of said compound(s). Still other embodiments described herein relate to one or more compounds described herein, or a pharmaceutically acceptable salt of a compound described herein, that can be used for ameliorating and/or treating a viral infection by contacting a cell infected with the virus with an effective amount of said compound(s). In some embodiments, the compound can be a compound of Formula (I), or a pharmaceutical acceptable salt thereof. In other embodiments, the compound can be a mono-, di- and/or tri-phosphate of a compound of Formula (I), or a pharmaceutically acceptable salt of the foregoing. In some embodiments, the virus can be a HCV virus.

[0156] Some embodiments disclosed herein relate to methods of inhibiting replication of a virus that can include contacting a cell infected with the virus with an effective amount of one or more compounds described herein, or a pharmaceutically acceptable salt of a compound described herein, or a pharmaceutical composition that includes one or more compounds described herein, or a pharmaceutically acceptable salt thereof. Other embodiments described herein relate to using one or more compounds described herein, or a pharmaceutically acceptable salt of a compound described herein, in the manufacture of a medicament for inhibiting replication of a virus that can include contacting a cell infected with the virus with an effective amount of said compound(s). Still other embodiments described herein relate to a compound described herein, or a pharmaceutically acceptable salt of a compound described herein, that can be used for inhibiting replication of a virus by contacting a cell infected with the virus with an effective amount of said compound(s). In some embodiments, the compound can be a compound of Formula (I), or a pharmaceutical acceptable salt thereof. In other embodiments, the compound can be a mono-, di- and/or tri-phosphate of a compound of Formula (I), or a pharmaceutically acceptable salt of the foregoing. In some embodiments, the virus can be a HCV virus.

[0157] HCV is an enveloped positive strand RNA virus in the Flaviviridae family. There are various nonstructural proteins of HCV, such as NS2, NS3, NS4, NS4A, NS4B, NS5A, and NS5B. NS5B is believed to be an RNA-dependent RNA polymerase involved in the replication of HCV RNA.

[0158] Some embodiments described herein relate to a method of inhibiting NS5B polymerase activity that can include contacting a cell (for example, a cell infected with HCV) with an effective amount of a compound of Formula (I), or a pharmaceutical acceptable salt thereof. Some embodiments described herein relate to a method of inhibiting NS5B polymerase activity that can include administering a cell (for example, a cell infected with HCV) with an effective amount of a compound of Formula (I), or a pharmaceutical acceptable salt thereof. In some embodiments, a compound of Formula (I), or a pharmaceutically acceptable salt thereof, can inhibit a RNA dependent RNA polymerase. In some embodiments, a compound of Formula (I), or a pharmaceutically acceptable salt thereof, can inhibit a HCV polymerase (for example, NS5B polymerase).

[0159] Some embodiments described herein relate to a method of treating HCV infection in a subject suffering from a HCV infection that can include administering to the subject an effective amount of a compound of Formula (I), or a pharmaceutical acceptable salt thereof, or a pharmaceutical composition that includes an effective amount of a compound of Formula (I), or a pharmaceutical acceptable salt thereof. Some embodiments described herein relate to a method of treating a condition selected from liver fibrosis, liver cirrohis, and liver cancer in a subject suffering from one or more of the aforementioned liver conditions that can include administering to the subject an effective amount of a compound or a pharmaceutical composition described herein (for example, a compound of Formula (I), or a pharmaceutical acceptable salt thereof). One cause of liver fibrosis, liver cirrohis, and/or liver cancer can be a HCV infection. Some embodiments described herein relate to a method of increasing liver function in a subject having a HCV infection that can include administering to the subject an effective amount of a compound or a pharmaceutical composition described herein (for example, a compound of Formula (I), or a pharmaceutical acceptable salt thereof). Also contemplated is a method for reducing or eliminating further virus-caused liver damage in a subject having an HCV infection by administering to the subject an effective amount of a compound or a pharmaceutical composition described herein (for example, a compound of Formula (I), or a pharmaceutical acceptable salt thereof). In some embodiments, this method can include slowing or halting the progression of liver disease. In other embodiments, the course of the disease can be reversed, and stasis or improvement in liver function is contemplated.

[0160] There are a variety of genotypes of HCV, and a variety of subtypes within each genotype. For example, at present it is known that there are eleven (numbered 1 through 11) main genotypes of HCV, although others have classified the genotypes as 6 main genotypes. Each of these genotypes is further subdivided into subtypes (la-lc; 2a-2c; 3a-3b; 4a-4e; 5a; 6a; 7a- 7b; 8a-8b; 9a; 10a; and 1 1a). In some embodiments, an effective amount of a compound of Formula (I), or a pharmaceutical acceptable salt thereof, or a pharmaceutical composition that includes an effective amount of a compound of Formula (I), or a pharmaceutical acceptable salt thereof, can be effective to treat at least one genotype of HCV. In some embodiments, a compound described herein (for example, a compound of Formula (I), or a pharmaceutical acceptable salt thereof) can be effective to treat all 11 genotypes of HCV. In some embodiments, a compound described herein (for example, a compound of Formula (I), or a pharmaceutical acceptable salt thereof) can be effective to treat 3 or more, 5 or more, 7 or more, or 9 or more genotypes of HCV. In some embodiments, a compound of Formula (I), or a pharmaceutical acceptable salt thereof can be more effective against a larger number of HCV genotypes than the standard of care. In some embodiments, a compound of Formula (I), or a pharmaceutical acceptable salt thereof, can be more effective against a particular HCV genotype than the standard of care (such as genotype 1, 2, 3, 4, 5 and/or 6).

[0161] Various indicators for determining the effectiveness of a method for treating a HCV infection are known to those skilled in the art. Examples of suitable indicators include, but are not limited to, a reduction in viral load, a reduction in viral replication, a reduction in time to seroconversion (virus undetectable in patient serum), an increase in the rate of sustained viral response to therapy, a reduction of morbidity or mortality in clinical outcomes, a reduction in the rate of liver function decrease; stasis in liver function; improvement in liver function; reduction in one or more markers of liver dysfunction, including alanine transaminase, aspartate transaminase, total bilirubin, conjugated bilirubin, gamma glutamyl transpeptidase, and/or other indicator of disease response. Similarly, successful therapy with an effective amount of a compound or a pharmaceutical composition described herein (for example, a compound of Formula (I), or a pharmaceutical acceptable salt thereof) can reduce the incidence of liver cancer in HCV infected subjects.

[0162] In some embodiments, an effective amount of a compound of Formula (I), or a pharmaceutically acceptable salt thereof, is an amount that is effective to reduce viral titers to undetectable levels, for example, to about 1000 to about 5000, to about 500 to about 1000, or to about 100 to about 500 genome copies/mL serum. In some embodiments, an effective amount of a compound of Formula (I), or a pharmaceutically acceptable salt thereof, is an amount that is effective to reduce viral load compared to the viral load before administration of the compound of Formula (I), or a pharmaceutically acceptable salt thereof. For example, wherein the viral load is measured before administration of the compound of Formula (I), or a pharmaceutically acceptable salt thereof, and again after completion of the treatment regime with the compound of Formula (I), or a pharmaceutically acceptable salt thereof (for example, 1 month after completion). In some embodiments, an effective amount of a compound of Formula (I), or a pharmaceutically acceptable salt thereof, can be an amount that is effective to reduce viral load to lower than about 100 genome copies/mL serum. In some embodiments, an effective amount of a compound of Formula (I), or a pharmaceutically acceptable salt thereof, is an amount that is effective to achieve a reduction in viral titer in the serum of the subject in the range of about 1.5- log to about a 2.5 -log reduction, about a 3 -log to about a 4-log reduction, or a greater than about 5 -log reduction compared to the viral load before administration of the compound of Formula (I), or a pharmaceutically acceptable salt thereof. For example, the viral load can be measured before administration of the compound of Formula (I), or a pharmaceutically acceptable salt thereof, and again after completion of the treatment regime with the compound of Formula (I), or a pharmaceutically acceptable salt thereof (for example, 1 month after completion).

[0163] In some embodiments, a compound of Formula (I), or a pharmaceutically acceptable salt thereof, can result in at least a 1, 2, 3, 4, 5, 10, 15, 20, 25, 50, 75, 100-fold or more reduction in the replication of HCV relative to pre-treatment levels in a subject, as determined after completion of the treatment regime (for example 1 month after completion). In some embodiments, a compound of Formula (I), or a pharmaceutically acceptable salt thereof, can result in a reduction of the replication of HCV relative to pre-treatment levels in the range of about 2 to about 5 fold, about 10 to about 20 fold, about 15 to about 40 fold, or about 50 to about 100 fold. In some embodiments, a compound of Formula (I), or a pharmaceutically acceptable salt thereof, can result in a reduction of HCV replication in the range of 1 to 1.5 log, 1.5 log to 2 log, 2 log to 2.5 log, 2.5 to 3 log, 3 log to 3.5 log or 3.5 to 4 log more reduction of HCV replication compared to the reduction of HCV reduction achieved by pegylated interferon in combination with ribavirin, administered according to the standard of care, or may achieve the same reduction as that standard of care therapy in a shorter period of time, for example, in one month, two months, or three months, as compared to the reduction achieved after six months of standard of care therapy with ribavirin and pegylated interferon.

[0164] In some embodiments, an effective amount of a compound of Formula (I), or a pharmaceutically acceptable salt thereof, is an amount that is effective to achieve a sustained viral response, for example, non-detectable or substantially non-detectable HCV RNA (e.g., less than about 500, less than about 400, less than about 200, or less than about 100 genome copies per milliliter serum) is found in the subject's serum for a period of at least about one month, at least about two months, at least about three months, at least about four months, at least about five months, or at least about six months following cessation of therapy.

[0165] In some embodiments, a therapeutically effective amount of a compound of Formula (I), or a pharmaceutically acceptable salt thereof, can reduce a level of a marker of liver fibrosis by at least about 10%, at least about 20%, at least about 25%, at least about 30%, at least about 35%, at least about 40%, at least about 45%, at least about 50%, at least about 55%, at least about 60%>, at least about 65%, at least about 70%, at least about 75%, or at least about 80%), or more, compared to the level of the marker in an untreated subject, or to a placebo- treated subject. Methods of measuring serum markers are known to those skilled in the art and include immunological-based methods, e.g., enzyme-linked immunosorbent assays (ELISA), radioimmunoassays, and the like, using antibody specific for a given serum marker. A non- limiting list of example markers includes measuring the levels of serum alanine aminotransferase (ALT), asparatate aminotransferacse (AST), alkaline phosphatase (ALP), gamma-glutamyl transpeptidase (GGT) and total bilirubin (TBIL) using known methods. In general, an ALT level of less than about 45 IU/L (international units/liter), an AST in the range of 10-34 IU/L, ALP in the range of 44-147 IU/L, GGT in the range of 0- 1 IU/L, TBIL in the range of 0.3-1.9 mg/dL is considered normal. In some embodiments, an effective amount of a compound of Formula (I), or a pharmaceutically acceptable salt thereof, can be an amount effective to reduce ALT, AST, ALP, GGT and/or TBIL levels to with what is considered a normal level.

[0166] Subjects who are clinically diagnosed with HCV infection include "naive" subjects (e.g., subjects not previously treated for HCV, particularly those who have not previously received IFN-alpha-based and/or ribavirin-based therapy) and individuals who have failed prior treatment for HCV ("treatment failure" subjects). Treatment failure subjects include "non-responders" (i.e., subjects in whom the HCV titer was not significantly or sufficiently reduced by a previous treatment for HCV (< 0.5 log IU/mL), for example, a previous IFN-alpha monotherapy, a previous IFN-alpha and ribavirin combination therapy, or a previous pegylated IFN-alpha and ribavirin combination therapy); and "relapsers" (i.e., subjects who were previously treated for HCV, for example, who received a previous IFN-alpha monotherapy, a previous IFN-alpha and ribavirin combination therapy, or a previous pegylated IFN-alpha and ribavirin combination therapy, whose HCV titer decreased, and subsequently increased).

[0167] In some embodiments, a compound of Formula (I), or a pharmaceutically acceptable salt thereof, can be administered to a treatment failure subject suffering from HCV. In some embodiments, a compound of Formula (I), or a pharmaceutically acceptable salt thereof, can be administered to a non-responder subject suffering from HCV. In some embodiments, a compound of Formula (I), or a pharmaceutically acceptable salt thereof, can be administered to a relapsed subject suffering from HCV.

[0168] After a period of time, infectious agents can develop resistance to one or more therapeutic agents. The term "resistance" as used herein refers to a viral strain displaying a delayed, lessened and/or null response to a therapeutic agent(s). For example, after treatment with an antiviral agent, the viral load of a subject infected with a resistant virus may be reduced to a lesser degree compared to the amount in viral load reduction exhibited by a subject infected with a non-resistant strain. In some embodiments, a compound of Formula (I), or a pharmaceutically acceptable salt thereof, can be administered to a subject infected with an HCV strain that is resistant to one or more different anti-HCV agents. In some embodiments, development of resistant HCV strains is delayed when a subject is treated with a compound of Formula (I), or a pharmaceutically acceptable salt thereof, compared to the development of HCV strains resistant to other HCV drugs.

[0169] In some embodiments, an effective amount of a compound of Formula (I), or a pharmaceutically acceptable salt thereof, can be administered to a subject for whom other anti- HCV medications are contraindicated. For example, administration of pegylated interferon alpha in combination with ribavirin is contraindicated in subjects with hemoglobinopathies (e.g., thalassemia major, sickle-cell anemia) and other subjects at risk from the hematologic side effects of current therapy. In some embodiments, a compound of Formula (I), or a pharmaceutically acceptable salt thereof, can be provided to a subject that is hypersensitive to interferon and/or ribavirin.

[0170] Some subjects being treated for HCV experience a viral load rebound. The term "viral load rebound" as used herein refers to a sustained >0.5 log IU/mL increase of viral load above nadir before the end of treatment, where nadir is a >0.5 log IU/mL decrease from baseline. In some embodiments, a compound of Formula (I), or a pharmaceutically acceptable salt thereof, can be administered to a subject experiencing viral load rebound, or can prevent such viral load rebound when used to treat the subject.

[0171] The standard of care for treating HCV has been associated with several side effects (adverse events). In some embodiments, a compound of Formula (I), or a pharmaceutically acceptable salt thereof, can decrease the number and/or severity of a side effect that can be observed in HCV patients being treated with ribavirin and pegylated interferon according to the standard of care. Examples of side effects include, but are not limited to fever, malaise, tachycardia, chills, headache, arthralgias, myalgias, fatigue, apathy, loss of apetite, nausea, vomiting, cognitive changes, asthenia, drowsiness, lack of initiative, irritability, confusion, depression, severe depression, suicidal ideation, anemia, low white blood cell counts, and thinning of hair. In some embodiments, a compound of Formula (I), or a pharmaceutically acceptable salt thereof, can be provided to a subject that discontinued a HCV therapy because of one or more adverse effects or side effects associated with one or more other HCV agents.

[0172] Table 4 provides some embodiments of the percentage improvement obtained using a compound of Formula (I), or a pharmaceutically acceptable salt thereof, as compared to the standard of care. Examples include the following: in some embodiments, a compound of Formula (I), or a pharmaceutically acceptable salt thereof, results in a percentage of non- responders that is 10% less than the percentage of non-responders receiving the standard of care; in some embodiments, a compound of Formula (I), or a pharmaceutically acceptable salt thereof, results in a number of side effects that is in the range of about 10% to about 30% less than compared to the number of side effects experienced by a subject receiving the standard of care; and in some embodiments, a compound of Formula (I), or a pharmaceutically acceptable salt thereof, results in a severity of a side effect (such as one of those described herein) that is 25% less than compared to the severity of the same side effect experienced by a subject receiving the standard of care. Methods of quantifying the severity of a side effect are known to those skilled in the art.

Table 4

[0173] Yet still other embodiments disclosed herein relate to a method of ameliorating or treating a parasitic disease that can include administering to a subject suffering from a parasitic disease a therapeutically effective amount of one or more compounds described herein (for example, a compound of Formula (I)), or a pharmaceutical composition that includes one or more compounds described herein. In some embodiments, the parasite disease can be Chagas' disease.

[0174] As used herein, a "subject" refers to an animal that is the object of treatment, observation or experiment. "Animal" includes cold- and warm-blooded vertebrates and invertebrates such as fish, shellfish, reptiles and, in particular, mammals. "Mammal" includes, without limitation, mice, rats, rabbits, guinea pigs, dogs, cats, sheep, goats, cows, horses, primates, such as monkeys, chimpanzees, and apes, and, in particular, humans. In some embodiments, the subject is human.

[0175] As used herein, the terms "treating," "treatment," "therapeutic," or "therapy" do not necessarily mean total cure or abolition of the disease or condition. Any alleviation of any undesired signs or symptoms of a disease or condition, to any extent can be considered treatment and/or therapy. Furthermore, treatment may include acts that may worsen the patient's overall feeling of well-being or appearance.

[0176] The terms "therapeutically effective amount" and "effective amount" are used to indicate an amount of an active compound, or pharmaceutical agent, that elicits the biological or medicinal response indicated. For example, a therapeutically effective amount of compound can be the amount needed to prevent, alleviate or ameliorate symptoms of disease or prolong the survival of the subject being treated. This response may occur in a tissue, system, animal or human and includes alleviation of the signs or symptoms of the disease being treated. Determination of a therapeutically effective amount is well within the capability of those skilled in the art, in view of the disclosure provided herein. The therapeutically effective amount of the compounds disclosed herein required as a dose will depend on the route of administration, the type of animal, including human, being treated, and the physical characteristics of the specific animal under consideration. The dose can be tailored to achieve a desired effect, but will depend on such factors as weight, diet, concurrent medication and other factors which those skilled in the medical arts will recognize.

[0177] As will be readily apparent to one skilled in the art, the useful in vivo dosage to be administered and the particular mode of administration will vary depending upon the age, weight, the severity of the affliction, and mammalian species treated, the particular compounds employed, and the specific use for which these compounds are employed. The determination of effective dosage levels, that is the dosage levels necessary to achieve the desired result, can be accomplished by one skilled in the art using routine methods, for example, human clinical trials and in vitro studies.

[0178] The dosage may range broadly, depending upon the desired effects and the therapeutic indication. Alternatively dosages may be based and calculated upon the surface area of the patient, as understood by those of skill in the art. Although the exact dosage will be determined on a drug-by-drug basis, in most cases, some generalizations regarding the dosage can be made. The daily dosage regimen for an adult human patient may be, for example, an oral dose of between 0.01 mg and 3000 mg of each active ingredient, preferably between 1 mg and 700 mg, e.g. 5 to 200 mg. The dosage may be a single one or a series of two or more given in the course of one or more days, as is needed by the subject. In some embodiments, the compounds will be administered for a period of continuous therapy, for example for a week or more, or for months or years. In some embodiments, a compound of Formula (I), or a pharmaceutically acceptable salt thereof, can be administered less frequently compared to the frequency of administration of an agent within the standard of care. In some embodiments, a compound of Formula (I), or a pharmaceutically acceptable salt thereof, can be administered one time per day. For example, a compound of Formula (I), or a pharmaceutically acceptable salt thereof, can be administered one time per day to a subject suffering from a HCV infection. In some embodiments, the total time of the treatment regime with a compound of Formula (I), or a pharmaceutically acceptable salt thereof, can less compared to the total time of the treatment regime with the standard of care.

[0179] In instances where human dosages for compounds have been established for at least some condition, those same dosages may be used, or dosages that are between about 0.1% and 500%, more preferably between about 25% and 250% of the established human dosage. Where no human dosage is established, as will be the case for newly-discovered pharmaceutical compositions, a suitable human dosage can be inferred from ED5 ₀ or ID5 ₀ values, or other appropriate values derived from in vitro or in vivo studies, as qualified by toxicity studies and efficacy studies in animals.

[0180] In cases of administration of a pharmaceutically acceptable salt, dosages may be calculated as the free base. As will be understood by those of skill in the art, in certain situations it may be necessary to administer the compounds disclosed herein in amounts that exceed, or even far exceed, the above-stated, preferred dosage range in order to effectively and aggressively treat particularly aggressive diseases or infections.

[0181] Dosage amount and interval may be adjusted individually to provide plasma levels of the active moiety which are sufficient to maintain the modulating effects, or minimal effective concentration (MEC). The MEC will vary for each compound but can be estimated from in vitro data. Dosages necessary to achieve the MEC will depend on individual characteristics and route of administration. However, HPLC assays or bioassays can be used to determine plasma concentrations. Dosage intervals can also be determined using MEC value. Compositions should be administered using a regimen which maintains plasma levels above the MEC for 10-90% of the time, preferably between 30-90% and most preferably between 50-90%). In cases of local administration or selective uptake, the effective local concentration of the drug may not be related to plasma concentration.

[0182] It should be noted that the attending physician would know how to and when to terminate, interrupt, or adjust administration due to toxicity or organ dysfunctions. Conversely, the attending physician would also know to adjust treatment to higher levels if the clinical response were not adequate (precluding toxicity). The magnitude of an administrated dose in the management of the disorder of interest will vary with the severity of the condition to be treated and to the route of administration. The severity of the condition may, for example, be evaluated, in part, by standard prognostic evaluation methods. Further, the dose and perhaps dose frequency, will also vary according to the age, body weight, and response of the individual patient. A program comparable to that discussed above may be used in veterinary medicine.

[0183] Compounds disclosed herein can be evaluated for efficacy and toxicity using known methods. For example, the toxicology of a particular compound, or of a subset of the compounds, sharing certain chemical moieties, may be established by determining in vitro toxicity towards a cell line, such as a mammalian, and preferably human, cell line. The results of such studies are often predictive of toxicity in animals, such as mammals, or more specifically, humans. Alternatively, the toxicity of particular compounds in an animal model, such as mice, rats, rabbits, or monkeys, may be determined using known methods. The efficacy of a particular compound may be established using several recognized methods, such as in vitro methods, animal models, or human clinical trials. When selecting a model to determine efficacy, the skilled artisan can be guided by the state of the art to choose an appropriate model, dose, route of administration and/or regime.

Combination Therapies

[0184] In some embodiments, the compounds disclosed herein, such as a compound of Formula (I), or a pharmaceutically acceptable salt thereof, or a pharmaceutical composition that includes a compound described herein, or a pharmaceutically acceptable salt thereof, can be used in combination with one or more additional agent(s). Examples of additional agents that can be used in combination with a compound of Formula (I), or a pharmaceutically acceptable salt thereof, or a pharmaceutical composition that includes a compound of Formula (I), or a pharmaceutically acceptable salt thereof, include, but are not limited to, agents currently used in a conventional standard of care for treating HCV, HCV protease inhibitors, HCV polymerase inhibitors, NS5A inhibitors, other antiviral compounds, compounds of Formula (AA) (including mono-, di, and/or tri-phosphates of Formula (AA), pharmaceutically acceptable salts and pharmaceutical compositions that can include a compound of Formula (AA), mono-, di- and/or tri- phosphates thereof, or a pharmaceutically acceptable salt of the foregoing), compounds of Formula (CC) (including pharmaceutically acceptable salts and pharmaceutical compositions that can include a compound of Formula (CC), or a pharmaceutically acceptable salt thereof), compounds of Formula (DD) (including pharmaceutically acceptable salts and pharmaceutical compositions that can include a compound of Formula (DD), or a pharmaceutically acceptable salt thereof), and/or combinations thereof. In some embodiments, a compound of Formula (I), or a pharmaceutically acceptable salt thereof, or a pharmaceutical composition that includes a compound of Formula (I), or a pharmaceutically acceptable salt thereof, can be used with one, two, three or more additional agents described herein. A non-limiting list of examples of combinations of a compound of Formula (I), or a pharmaceutically acceptable salt thereof, or a pharmaceutical composition that includes a compound of Formula (I), or a pharmaceutically acceptable salt thereof, is provided in Tables A, B, C and D.

[0185] In some embodiments, a compound of Formula (I), or a pharmaceutically acceptable salt thereof, or a pharmaceutical composition that includes a compound of Formula (I), or a pharmaceutically acceptable salt thereof, can be used in combination with an agent(s) currently used in a conventional standard of care therapy. For example, for the treatment of HCV, a compound disclosed herein can be used in combination with Pegylated interferon-alpha- 2a (brand name PEGASYS®) and ribavirin, or Pegylated interferon-alpha-2b (brand name PEG- INT ON®) and ribavirin. As another example, a compound disclosed herein can be used in combination with oseltamivir (TAMIFLU®) or zanamivin (RELENZA®) for treating an influenza infection.

[0186] In some embodiments, a compound of Formula (I), or a pharmaceutically acceptable salt thereof, or a pharmaceutical composition that includes a compound of Formula (I), or a pharmaceutically acceptable salt thereof, can be substituted for an agent currently used in a conventional standard of care therapy. For example, for the treatment of HCV, a compound of Formula (I), or a pharmaceutically acceptable salt thereof, or a pharmaceutical composition that includes a compound of Formula (I), or a pharmaceutically acceptable salt thereof, can be used in place of ribavirin.

[0187] In some embodiments, a compound of Formula (I), or a pharmaceutically acceptable salt thereof, or a pharmaceutical composition that includes a compound of Formula (I), or a pharmaceutically acceptable salt thereof, can be used in combination with an interferon, such as a pegylated interferon. Examples of suitable interferons include, but are not limited to, Pegylated interferon-alpha-2a (brand name PEGASYS®), Pegylated interferon-alpha-2b (brand name PEG-INTRON®), interferon alfacon-1 (brand name INFERGEN®), pegylated interferon lambda and/or a combination thereof.

[0188] In some embodiments, a compound of Formula (I), or a pharmaceutically acceptable salt thereof, or a pharmaceutical composition that includes a compound of Formula (I), or a pharmaceutically acceptable salt thereof, can be used in combination with a HCV protease inhibitor. A non-limiting list of example HCV protease inhibitors include the following: VX-950 (TELAPRE VIR®) , MK-5172, ABT-450, BILN-2061 , BI-201335, BMS- 650032, SCH 503034 (BOCEPREVIR®), GS-9256, GS-9451, IDX-320, ACH-1625, ACH- 2684, TMC-435, ITMN-191 (DANOPREVIR®) and/or a combination thereof. A non-limiting list of example HCV protease inhibitors includes the compounds numbered 1001-1014 in Figures 1A-1B.

[0189] In some embodiments, a compound of Formula (I), or a pharmaceutically acceptable salt thereof, or a pharmaceutical composition that includes a compound of Formula (I), or a pharmaceutically acceptable salt thereof, can be used in combination with a HCV polymerase inhibitor. In some embodiments, the HCV polymerase inhibitor can be a nucleoside inhibitor. In other embodiments, the HCV polymerase inhibitor can be a non-nucleoside inhibitor. Examples of suitable nucleoside inhibitors include, but are not limited to, RG7128, PSI-7851 , PSI-7977, INX-189, PSI-352938, PSI-661, 4'-azidouridine (including known prodrugs of 4'-azidouridine), GS-6620, IDX-184 and TMC649128, and/or combinations thereof. A non- limiting list of example nucleoside inhibitors includes compounds numbered 2001-2010 in Figure 2. Examples of suitable non-nucleoside inhibitors include, but are not limited to, ABT-333, ANA-598, VX-222, HCV-796, BI-207127, GS-9190, PF-00868554 (FILIBUVIR®), VX-497 and/or combinations thereof. A non-limiting list of example non-nucleoside inhibitors includes the compounds numbered 3001-3008 in Figure 3.

[0190] In some embodiments, a compound of Formula (I), or a pharmaceutically acceptable salt thereof, or a pharmaceutical composition that includes a compound of Formula (I), or a pharmaceutically acceptable salt thereof, can be used in combination with a NS5A inhibitor. A non-limiting list of example NS A inhibitors include BMS-790052, PPI-461 , ACH-2928, GS-5885, BMS-824393 and/or combinations thereof. A non-limiting list of example NS A inhibitors includes the compounds numbered 4001-4005 in Figure 4.

[0191] In some embodiments, a compound of Formula (I), or a pharmaceutically acceptable salt thereof, or a pharmaceutical composition that includes a compound of Formula (I), or a pharmaceutically acceptable salt thereof, can be used in combination with other antiviral compounds. Examples of other antiviral compounds include, but are not limited to, Debio-025, MIR- 122 and/or combinations thereof. A non-limiting list of example other antiviral compounds includes the compounds numbered 5001-5002 in Figure 5.

[0192] In some embodiments, a compound of Formula (I), or a pharmaceutically acceptable salt thereof, or a pharmaceutical composition that includes a compound of Formula (I), or a pharmaceutically acceptable salt thereof, can be used in combination with a compound of Formula (AA), mono-, di- and/or tri-phosphate thereof, or a pharmaceutically acceptable salt of the foregoing, or a pharmaceutical composition that includes a compound of Formula (AA), mono-, di- and/or tri-phosphate thereof, or a pharmaceutically acceptable salt of the foregoing (see, U.S. Application No. 13/236,450, filed September 19, 2011 , and U.S. Provisional Application Nos. 61/385,425, filed September 22, 2010, and 61/426,467, filed December 22, 2010, the contents of which are incorporated by reference in their entireties):

Formula (AA) wherein B^ ¹ can be an optionally substituted heterocyclic base or an optionally substituted heterocyclic base with a protected amino group; R^ ¹ can be an optionally substituted N-linked amino acid or an optionally substituted N-linked amino acid ester derivative; R^ can be selected from an optionally substituted aryl, an optionally substituted heteroaryl and an optionally substituted heterocyclyl; R ^{AA a} and R ^AA3h can be independently selected from hydrogen, an optionally substituted Ci_6 alkyl, an optionally substituted C ₂ _6 alkenyl, an optionally substituted C ₂ -6 alkynyl, an optionally substituted Ci_6 haloalkyl and aryl(Ci_6 alkyl), provided that at least one of R ^AA3a and R^ ³ * ⁵ is not hydrogen; or R^ ³ * and R^ ³¹⁵ can be taken together to form a group selected from an optionally substituted C ₃ _6 cycloalkyl, an optionally substituted C3-6 cycloalkenyl, an optionally substituted C ₃ -6 aryl, and an optionally substituted C3-6 heteroaryl; R^ ⁴ can be hydrogen; R^ ⁵ can be selected from hydrogen, -OR^ ⁴⁹ and - OC(=0)R ^AA1 °; R^ ⁵ can be selected from hydrogen, halogen, -OR^ ¹¹ and -OC(=0)R ^AA12 ; or R^ ⁵ and R^ ⁶ can be both oxygen atoms and linked together by a carbonyl group; R^ ⁷ can be selected from hydrogen, halogen, an optionally substituted Ci_6 alkyl, -OR^ ¹ and -

O )CC((==(0)R ^AA14 ; R^ ⁸ can be hydrogen or an optionally substituted Ci_ ₆ alkyl; R^ ⁹ , R^ ¹¹ and

R^ ¹ can be independently selected from hydrogen and an optionally substituted Ci_6 alkyl; and ΑΑΐο^ pAAi2 _an( j p AAi4 _can ^ _g ^(jgp endeiitly selected from an optionally substituted C _i _6 alkyl and an optionally substituted C ₃ -6 cycloalkyl. A non-limiting list of examples of compounds of Formula (AA), and phosphates thereof, includes the compounds numbered 7000-7077 in Figures 7A-70. In some embodiments, Formula (AA) cannot be compound 7044, 7045, 7046, 7047, 7048, 7049, 7050, 7072, 7073, 7074, 7075, 7076 or 7077.

[0193] In some embodiments, a compound of Formula (I), or a pharmaceutically acceptable salt thereof, or a pharmaceutical composition that includes a compound of Formula (I), or a pharmaceutically acceptable salt thereof, can be used in combination with a compound of Formula (CC), or a pharmaceutically acceptable salt thereof, or a pharmaceutical composition that includes a compound of Formula (CC), or a pharmaceutically acceptable salt thereof (see, U.S. Application No. 13/236,435, filed September 19, 2011, and U.S. Provisional Application Nos. 61/385,363, filed September 22, 2010, and 61/426,461, filed December 22, 2010, the contents of which are incorporated by reference in their entireties):

Formula (CC) wherein B^ ¹ can be an optionally substituted heterocyclic base or an optionally substituted heterocyclic base with a protected amino group; R ^CC1 can be selected from O ^" , OH, an optionally substituted N-linked amino acid and an optionally substituted N-linked amino acid ester derivative; R ^CC2 can be selected from an optionally substituted aryl, an optionally substituted

heteroaryl, an optionally substituted heterocyclyl and , wherein

R , R and R can be independently absent or hydrogen, and n can be 0 or 1 ; ded that when R ^CC1 is O ^" or OH, then R ^CC2 is R CC3a provi and R ^CC3b can be independently selected from hydrogen, deuterium, an optionally substituted Ci_6 alkyl, an optionally substituted C ₂ -6 alkenyl, an optionally substituted C ₂ -6 alkynyl, an optionally substituted Ci_6 haloalkyl and aryl(Ci_6 alkyl); or can be taken together to form an optionally substituted C3.6 cycloalkyl; R ^CC4 can be selected from hydrogen, azido, an optionally substituted Ci_6 alkyl, an optionally substituted C2-6 alkenyl and an optionally substituted C ₂ -6 alkynyl; R can be selected from hydrogen, halogen, azido, cyano, an optionally substituted Ci_ ₆ alkyl, -OR ^CC10 and -OC(=0)R ^CC11 ; R ^CC6 can be selected from hydrogen, halogen, azido, cyano, an optionally substituted Ci_6 alkyl, -OR and - OC(=0)R ; R can be selected from hydrogen, halogen, azido, cyano, an optionally substituted Ci_ ₆ alkyl, -OR ^CC14 and -OC(=0)R ^CC15 ; or R ^CC6 and R ^CC7 can be both oxygen atoms

008

and linked together by a carbonyl group; R can be selected from hydrogen, halogen, azido, cyano, an optionally substituted Ci_ ₆ alkyl, -OR ^CC16 and -OC(=0)R ^CC17 ; R ^CC9 can be selected

CC18. n CCIO _D CC12 from hydrogen, azido, cyano, an optionally substituted Ci_6 alkyl and -OR ¹ R" R"

CC14 , CC18

R' R ^CC16 and R ^UU18 can be independently selected from hydrogen and an optionally substituted Ci_ ₆ alkyl; and R ^CC11 , R ^CC13 , R ^CC15 and R ^CC17 can be independently selected from an optionally substituted Ci_6 alkyl and an optionally substituted C ₃ _e cycloalkyl. In some embodiments, when R ^{CC a} , R ^CC3b , R ^CC4 , R ^CC5 , R ^CC7 , R ^CC8 and R ^CC9 are all hydrogen, then R ^CC6 is

not azido. In some embodiments, R cannot be when R ^CC3a is hydrogen, R ^{CC b} is hydrogen, R ^CC4 is H, R ^CC5 is OH or H, R ^UUD is hydrogen, OH, or - OC(=0)CH ₃ , R ^CC7 is hydrogen, OH, OCH ₃ or OC(=0)CH ₃ , R ^CC8 is hydrogen, OH or OCH ₃ , R^ is H and B is an optionally substituted adenine, an optionally substituted guanine, an optionally substituted uracil or an optionally substituted hypoxanthine. In some embodiments,

R cannot be A non-limiting list of examples of compounds of Formula (CC) includes the compounds numbered 6000-6078 in Figures 6A-6M.

[0194] In some embodiments, a compound of Formula (I), or a pharmaceutically acceptable salt thereof, or a pharmaceutical composition that includes a compound of Formula (I), or a pharmaceutically acceptable salt thereof, can be used in combination with a compound of Formula (DD), or a pharmaceutically acceptable salt thereof, or a pharmaceutical composition that includes a compound of Formula (DD), or a pharmaceutically acceptable salt thereof (see, e.g., U.S. Publication No. 2010-0249068, filed March 19, 2010, the contents of which are incorporated by reference in its entirety): Formula (DD)

wherein each can be independently a double or single bond; A ^DD1 can be selected from C

(carbon), O (oxygen) and S (sulfur); B ^DD1 can be an optionally substituted heterocyclic base or a derivative thereof; D ^DD1 can be selected from C=CH ₂ , CH ₂ , O (oxygen), S (sulfur), CHF, and CF ₂ ; R ^DD1 can be hydrogen, an optionally substituted alkyl, an optionally substituted cycloalkyl, an optionally substituted aralkyl, dialkylaminoalkylene, alkyl— C(=0)—, aryl— C(=0)— , alkoxyalkyl— C(=0)— , aryloxyalkyl— C(=0)— , alkylsulfonyl, arylsulfonyl, aralkylsulfonyl, an -O-linked amino acid, diphosphate, triphosphate or derivatives thereof; R ^DD2 and R ^DD3 can be each independently selected from hydrogen, an optionally substituted Ci_e alkyl, an optionally substituted C ₂ _6 alkenyl, an optionally substituted C ₂ -6 alkynyl and an optionally substituted Ci_6 haloalkyl, provided that at least one of R ^DD2 and R ^DD3 cannot be hydrogen; or R ^DD2 and R ^DD3 are taken together to form a group selected from among C3_6 cycloalkyl, C3-6 cycloalkenyl, C ₃ -6 aryl, and a C _6 heteroaryl; R ^DD4 and R ^DD9 can be independently selected from hydrogen, halogen, -NH ₂ , -NHR ^DDal , _NR DD*i _R D ^DBL , -SR ^DDal , -CN, -NC, -N ₃ , -N0 ₂ , - N(R ^DDcl )-NR ^DDal R ^DDbl , -N(R ^DDcl )-OR ^DDal , -S-SR ^DDal , -C(=0)R ^DDal , -C(=0)OR ^DDal , - C(=0)NR ^DDal R ^DDbl , -0-(C=0)R ^DDal , -0-C(=0)OR ^DDal , -0-C(=0)NR ^DDal R ^DDbl , -N(R ^DDc1 )- C(=0)NR ^DDal R ^DDbl , -S(=0)R ^DDal , S(=0) ₂ R ^DDal , -0-S(=0) ₂ NR ^DDal R ^DDbl , -N(R ^DDc1 )- S(=0) ₂ NR ^DDal R ^DDbl , an optionally substituted Ci_ ₆ alkyl, an optionally substituted C ₂ _ ₆ alkenyl, an optionally substituted C ₂ _6 alkynyl, an optionally substituted aralkyl and an -O-linked amino acid; R ^DD5 , R ^DD6 and R ^DD7 can be independently absent or selected from hydrogen, halogen, - NH ₂ , -NHR ^DDal , _NR DDai _R DDM -OR ^DDal , -SR ^DDal , -CN, -NC, -N ₃ , -N0 ₂ , -N(R ^DDcl )-NR ^DDal R ^DDbl , -N(R ^DDcl )-OR ^DDal , -S-SR ^DDal , -C(=0)R ^DDal , -C(=0)OR ^DDal , -C(=0)NR ^DDal R ^DDbl , -O- (CO)R ^DDal , -0-C(=0)OR ^DDal , -0-C(=0)NR ^DDal R ^DDbl , -N(R ^DDcl )-C(=0)NR ^DDal R ^DDbl , - S(=0)R ^DDal , S(=0) ₂ R ^DDal , -0-S(=0) ₂ NR ^DDal R ^DDbl , -N(R ^DDcl )-S(=0) ₂ NR ^DDal R ^DDbl , an optionally substituted Ci_6 alkyl, an optionally substituted C2-6 alkenyl, an optionally substituted C ₂ _6 alkynyl, an optionally substituted aralkyl and an -O-linked amino acid; or R ^DD6 and R ^DD7 taken together form— O— C(=0)— O— ; R ^DD8 can be absent or selected from hydrogen, halogen, - NH ₂ , -NHR ^DDal , -OR ^DDal , -SR ^DDal , -CN, -NC, -N ₃ , -N0 ₂ , -N(R ^DDcl )-NR ^DDal R ^DDbl , -N(R ^DDcl )-OR ^DDal , -S-SR ^DDal , -C(=0)R ^DDal , -C(=0)OR ^DDal , -C(=0)NR ^DDal R ^DDbl , -O- C(=0)OR ^DDal , -0-C(=0)NR ^DDal R ^DDbl , -N(R ^DDcl )-C(=0)NR ^DDal R ^DDbl , -S(=0)R ^DDal , S(=0) ₂ R ^DDal , -0-S(=0) ₂ NR ^DDaI R ^DDbl , -N(R ^DDcl )-S(=0) ₂ NR ^DDal R ^DDbl , an optionally substituted Ci-6 alkyl, an optionally substituted C ₂ -6 alkenyl, an optionally substituted C ₂ _6 alkynyl, an optionally substituted haloalkyl, an optionally substituted hydroxyalkyl and an -O-linked amino acid, or when the bond to R ^DD7 indicated by is a double bond, then R ^DD7 is a C ₂ -6 alkylidene and R ^DD8 is absent; R ^DDal , R ^{DDB L} and R ^DDcl can be each independently selected from hydrogen, an optionally substituted alkyl, an optionally substituted alkenyl, an optionally substituted alkynyl, an optionally substituted aryl, an optionally substituted heteroaryl, an optionally substituted aralkyl and an optionally substituted heteroaryl(Ci_6 alkyl); R ^DD1 ° can be selected from 0 ^~ , -OH, an optionally substituted aryloxy or aryl-O-,

alkyl-C(=0)-0-CH ₂ -0-, alkyl-C(=0)-S-CH ₂ CH ₂ -0- and an -

N-linked ed from 0 ^~ , -OH, an optionally substituted aryloxy or

aryl-O-, alkyl-C(=0)-0-CH ₂ -0-, alkyl-C(=0)-S-CH ₂ CH ₂ -0- and an -N-linked amino acid; each R ^{DD 12} and each R ^DD _ca n be independently -C≡N or an optionally substituted substituent selected from Ci_8 organylcarbonyl, C _1-8 alkoxycarbonyl and Ci_8 organylaminocarbonyl; each R ^DD14 _C an be hydrogen or an optionally substituted Ci_6-alkyl; each m ^DD can be independently 1 or 2, and if both R ^DD10 _an d R DDI I each R ^DD12 , each R ^DD13 , each R ^{DD 14} and each m ^DD can be the same or different. In some embodiments, R ^DD8 can be halogen, -OR ^DDal , an optionally substituted Ci_<5 alkyl, an optionally substituted C ₂ _6 alkenyl, an optionally substituted C ₂ _6 alkynyl and an optionally substituted Ci_6 haloalkyl.

[0195] Some embodiments described herein relate to a method of ameliorating or treating a viral infection that can include contacting a cell infected with the viral infection with a therapeutically effective amount of a compound of Formula (I), or a pharmaceutically acceptable salt thereof, in combination with one or more agents selected from an interferon, ribavirin, a HCV protease inhibitor, a HCV polymerase inhibitor, a NS5A inhibitor, an antiviral compound, a compound of Formula (AA), a mono-, di, and/or tri-phosphate thereof, a compound of Formula (CC) and a compound of Formula (DD), or a pharmaceutically acceptable salt of any of the aforementioned compounds.

[0196] Some embodiments described herein relate to a method of ameliorating or treating a viral infection that can include administering to a subject suffering from the viral infection a therapeutically effective amount of a compound of Formula (I), or a pharmaceutically acceptable salt thereof, in combination with one or more agents selected from an interferon, ribavirin, a HCV protease inhibitor, a HCV polymerase inhibitor, a NS5A inhibitor, an antiviral compound, a compound of Formula (AA), a mono-, di, and/or triphosphate thereof, a compound of Formula (CC) and a compound of Formula (DD), or a pharmaceutically acceptable salt of any of the aforementioned compounds.

[0197] Some embodiments described herein relate to a method of inhibiting viral replication of a virus that can include contacting a cell infected with the virus an effective amount of a compound of Formula (I), or a pharmaceutically acceptable salt thereof, in combination with one or more agents selected from an interferon, ribavirin, a HCV protease inhibitor, a HCV polymerase inhibitor, a NS5A inhibitor, an antiviral compound, a compound of Formula (AA), a mono-, di, and/or tri-phosphate thereof, a compound of Formula (CC) and a compound of Formula (DD), or a pharmaceutically acceptable salt of any of the aforementioned compounds.

[0198] Some embodiments described herein relate to a method of ameliorating or treating a viral infection that can include contacting a cell infected with the viral infection with a therapeutically effective amount of a compound of Formula (I), or a pharmaceutically acceptable salt thereof, in combination with one or more agents selected from an interferon, ribavirin, a HCV protease inhibitor, a HCV polymerase inhibitor, a NS5A inhibitor, an antiviral compound, a compound of Formula (AA), a compound of Formula (CC) and a compound of Formula (DD), or a pharmaceutically acceptable salt of any of the aforementioned compounds.

[0199] Some embodiments described herein relate to a method of ameliorating or treating a viral infection that can include administering to a subject suffering from the viral infection a therapeutically effective amount of a compound of Formula (I), or a pharmaceutically acceptable salt thereof, in combination with one or more agents selected from an interferon, ribavirin, a HCV protease inhibitor, a HCV polymerase inhibitor, a NS5A inhibitor, an antiviral compound, a compound of Formula (AA), a compound of Formula (CC) and a compound of Formula (DD), or a pharmaceutically acceptable salt of any of the aforementioned compounds.

[0200] Some embodiments described herein relate to a method of inhibiting viral replication of a virus that can include contacting a cell infected with the virus an effective amount of a compound of Formula (I), or a pharmaceutically acceptable salt thereof, in combination with one or more agents selected from an interferon, ribavirin, a HCV protease inhibitor, a HCV polymerase inhibitor, a NS5A inhibitor, an antiviral compound, a compound of Formula (AA), a compound of Formula (CC) and a compound of Formula (DD), or a pharmaceutically acceptable salt of any of the aforementioned compounds.

[0201] In some embodiments, a compound of Formula (I), or a pharmaceutically acceptable salt thereof, can be administered with one or more additional agent(s) together in a single pharmaceutical composition. In some embodiments, a compound of Formula (I), or a pharmaceutically acceptable salt the thereof, can be administered with one or more additional agent(s) as two or more separate pharmaceutical compositions. For example, a compound of Formula (I), or a pharmaceutically acceptable salt thereof, can be administered in one pharmaceutical composition, and at least one of the additional agents can be administered in a second pharmaceutical composition. If there are at least two additional agents, one or more of the additional agents can be in a first pharmaceutical composition that includes a compound of Formula (I), or a pharmaceutically acceptable salt thereof, and at least one of the other additional agent(s) can be in a second pharmaceutical composition.

[0202] The dosing amount(s) and dosing schedule(s) when using a compound of Formula (I), or a pharmaceutically acceptable salt thereof, or a pharmaceutical composition that includes a compound of Formula (I), or a pharmaceutically acceptable salt thereof, and one or more additional agents are within the knowledge of those skilled in the art. For example, when performing a conventional standard of care therapy using art-recognized dosing amounts and dosing schedules, a compound of Formula (I), or a pharmaceutically acceptable salt thereof, or a pharmaceutical composition that includes a compound of Formula (I), or a pharmaceutically acceptable salt thereof, can be administered in addition to that therapy, or in place of one of the agents of a combination therapy, using effective amounts and dosing protocols as described herein.

[0203] The order of administration of a compound of Formula (I), or a pharmaceutically acceptable salt thereof, with one or more additional agent(s) can vary. In some embodiments, a compound of Formula (I), or a pharmaceutically acceptable salt thereof, can be administered prior to all additional agents. In other embodiments, a compound of Formula (I), or a pharmaceutically acceptable salt thereof, can be administered prior to at least one additional agent. In still other embodiments, a compound of Formula (I), or a pharmaceutically acceptable salt thereof, can be administered concomitantly with one or more additional agent(s). In yet still other embodiments, a compound of Formula (I), or a pharmaceutically acceptable salt thereof, can be administered subsequent to the administration of at least one additional agent. In some embodiments, a compound of Formula (I), or a pharmaceutically acceptable salt thereof, can be administered subsequent to the administration of all additional agents.

[0204] In some embodiments, the combination of a compound of Formula (I), or a pharmaceutically acceptable salt thereof, in combination with one or more additional agent(s) in Figures 1-7 and 9 (including pharmaceutically acceptable salts and prodrugs thereof) can result in an additive effect. In some embodiments, the combination of a compound of Formula (I), or a pharmaceutically acceptable salt thereof, in combination with one or more additional agent(s) in Figures 1 -7 and 9 (including pharmaceutically acceptable salts and prodrugs thereof) can result in a synergistic effect. In some embodiments, the combination of a compound of Formula (I), or a pharmaceutically acceptable salt thereof, in combination with one or more additional agent(s) in Figures 1-7 and 9 (including pharmaceutically acceptable salts and prodrugs thereof) can result in a strongly synergistic effect. In some embodiments, the combination of a compound of Formula (I), or a pharmaceutically acceptable salt thereof, in combination with one or more additional agent(s) in Figures 1-7 and 9 (including pharmaceutically acceptable salts and prodrugs thereof) is not antagonistic.

[0205] As used herein, the term "antagonistic" means that the activity of the combination of compounds is less compared to the sum of the activities of the compounds in combination when the activity of each compound is determined individually (i.e. as a single compound). As used herein, the term "synergistic effect" means that the activity of the combination of compounds is greater than the sum of the individual activities of the compounds in the combination when the activity of each compound is determined individually. As used herein, the term "additive effect" means that the activity of the combination of compounds is about equal to the sum of the individual activities of the compound in the combination when the activity of each compound is determined individually.

[0206] A potential advantage of utilizing a compound of Formula (I), or a pharmaceutically acceptable salt thereof, in combination with one or more additional agent(s) in Figures 1-7 and 9 (including pharmaceutically acceptable salts and prodrugs thereof) may be a reduction in the required amount(s) of one or more compounds of Figures 1-7 and 9 (including pharmaceutically acceptable salts and prodrugs thereof) that is effective in treating a disease condition disclosed herein (for example, HCV), as compared to the amount required to achieve same therapeutic result when one or more compounds of Figures 1-7 and 9 (including pharmaceutically acceptable salts and prodrugs thereof) are administered without a compound of Formula (I), or a pharmaceutically acceptable salt thereof. For example, the amount of a compound in Figures 1-7 and 9 (including a pharmaceutically acceptable salt and prodrug thereof), can be less compared to the amount of the compound in Figures 1-7 and 9 (including a pharmaceutically acceptable salt and prodrug thereof), needed to achieve the same viral load reduction when administered as a monotherapy. Another potential advantage of utilizing a compound of Formula (I), or a pharmaceutically acceptable salt thereof, in combination with one or more additional agent(s) in Figures 1-7 and 9 (including pharmaceutically acceptable salts and prodrugs thereof) is that the use of two or more compounds having different mechanism of actions can create a higher barrier to the development of resistant viral strains compared to the barrier when a compound is administered as monotherapy.

[0207] Additional advantages of utilizing a compound of Formula (I), or a pharmaceutically acceptable salt thereof, in combination with one or more additional agent(s) in Figures 1-7 and 9 (including pharmaceutically acceptable salts and prodrugs thereof) may include little to no cross resistance between a compound of Formula (I), or a pharmaceutically acceptable salt thereof, and one or more additional agent(s) in Figures 1-7 and 9 (including pharmaceutically acceptable salts and prodrugs thereof) thereof; different routes for elimination of a compound of Formula (I), or a pharmaceutically acceptable salt thereof, and one or more additional agent(s) in Figures 1-7 and 9 (including pharmaceutically acceptable salts and prodrugs thereof); little to no overlapping toxicities between a compound of Formula (I), or a pharmaceutically acceptable salt thereof, and one or more additional agent(s) in Figures 1 -7 and 9 (including pharmaceutically acceptable salts and prodrugs thereof); little to no significant effects on cytochrome P450; and/or little to no pharmacokinetic interactions between a compound of Formula (I), or a pharmaceutically acceptable salt thereof, and one or more additional agent(s) in Figures 1-7 and 9 (including pharmaceutically acceptable salts and prodrugs thereof).

[0208] A non-limiting list of example combination of compounds of Formula (I), or a pharmaceutically acceptable salt thereof, or a pharmaceutical composition that includes a compound described herein, with one or more additional agent(s) are provided in Tables A, B, C and D. Each numbered X and Y compound in Tables A, B, C and D has a corresponding name and/or structure provided in Figures 1 to 9. The numbered compounds in Tables A, B, C and D includes pharmaceutically acceptable salts of the compounds and pharmaceutical compositions containing the compounds or a pharmaceutically acceptable salt thereof. For example, 1001 includes the compound corresponding to 1001, pharmaceutically acceptable salts thereof, and pharmaceutical compositions that include compound 1001 and/or a pharmaceutically acceptable salt thereof. The combinations exemplified in Tables A, B, C and D are designated by the formula X:Y, which represents a combination of a compound X with a compound Y. For example, the combination designated as 1001 :8001 in Table A represents a combination of compound 1001 with compound 8001, including pharmaceutically acceptable salts of compound 1001 and/or 8001, and pharmaceutical compositions including compound 1001 and 8001 (including pharmaceutical compositions that include pharmaceutically acceptable salts of compound 1001 and/or compound 8001). Thus, the combination designated as 1001 :8001 in Table A represents the combination of Telaprevir (compound 1001, as shown in Figure 1A) and

(compound 8001, as shown in Figure 8A), including pharmaceutically acceptable salts of compound 1001 and/or 8001, and pharmaceutical compositions including compound 1001 and 8001 (including pharmaceutical compositions that include pharmaceutically acceptable salts of compound 1001 and/or compound 8001). Each of the combinations provided in Tables A, B, C and D can be used with one, two, three or more additional agents described herein. In some embodimentsdescribed herein, the combination of agents can be used to treat, amerliorate and/or inhibit a virus and/or a viral infection, wherein the virus can be HCV and the viral infection can be an HCV viral infection.

Table A: Example combinations of a compound X with a compound Y.

X Y X Y X Y X Y X Y X Y

1001 8000 1001 8001 1001 8002 1001 8003 1001 8004 1001 8005

1002 8000 1002 8001 1002 8002 1002 8003 1002 8004 1002 8005

1003 8000 1003 8001 1003 8002 1003 8003 1003 8004 1003 8005

1004 8000 1004 8001 1004 8002 1004 8003 1004 8004 1004 8005

1005 8000 1005 8001 1005 8002 1005 8003 1005 8004 1005 8005

1006 8000 1006 8001 1006 8002 1006 8003 1006 8004 1006 8005

1007 8000 1007 8001 1007 8002 1007 8003 1007 8004 1007 8005

1008 8000 1008 8001 1008 8002 1008 8003 1008 8004 1008 8005

1009 8000 1009 8001 1009 8002 1009 8003 1009 8004 1009 8005

1010 8000 1010 8001 1010 8002 1010 8003 1010 8004 1010 8005

1011 8000 1011 8001 1011 8002 1011 8003 1011 8004 1011 8005

1012 8000 1012 8001 1012 8002 1012 8003 1012 8004 1012 8005

1013 8000 1013 8001 1013 8002 1013 8003 1013 8004 1013 8005

1014 8000 1014 8001 1014 8002 1014 8003 1014 8004 1014 8005

2001 8000 2001 8001 2001 8002 2001 8003 2001 8004 2001 8005

2002 8000 2002 8001 2002 8002 2002 8003 2002 8004 2002 8005

2003 8000 2003 8001 2003 8002 2003 8003 2003 8004 2003 8005

2004 8000 2004 8001 2004 8002 2004 8003 2004 8004 2004 8005

2005 8000 2005 8001 2005 8002 2005 8003 2005 8004 2005 8005

2006 8000 2006 8001 2006 8002 2006 8003 2006 8004 2006 8005

2007 8000 2007 8001 2007 8002 2007 8003 2007 8004 2007 8005

2008 8000 2008 8001 2008 8002 2008 8003 2008 8004 2008 8005

2009 8000 2009 8001 2009 8002 2009 8003 2009 8004 2009 8005

2010 8000 2010 8001 2010 8002 2010 8003 2010 8004 2010 8005

3001 8000 3001 8001 3001 8002 3001 8003 3001 8004 3001 8005

3002 8000 3002 8001 3002 8002 3002 8003 3002 8004 3002 8005

3003 8000 3003 8001 3003 8002 3003 8003 3003 8004 3003 8005

3004 8000 3004 8001 3004 8002 3004 8003 3004 8004 3004 8005

3005 8000 3005 8001 3005 8002 3005 8003 3005 8004 3005 8005

3006 8000 3006 8001 3006 8002 3006 8003 3006 8004 3006 8005

3007 8000 3007 8001 3007 8002 3007 8003 3007 8004 3007 8005

3008 8000 3008 8001 3008 8002 3008 8003 3008 8004 3008 8005

4001 8000 4001 8001 4001 8002 4001 8003 4001 8004 4001 8005

4002 8000 4002 8001 4002 8002 4002 8003 4002 8004 4002 8005

4003 8000 4003 8001 4003 8002 4003 8003 4003 8004 4003 8005

4004 8000 4004 8001 4004 8002 4004 8003 4004 8004 4004 8005

4005 8000 4005 8001 4005 8002 4005 8003 4005 8004 4005 8005

5001 8000 5001 8001 5001 8002 5001 8003 5001 8004 5001 8005

5002 8000 5002 8001 5002 8002 5002 8003 5002 8004 5002 8005 X Y X Y X Υ X Υ X Υ X Υ

1001 8006 1001 8007 1001 8008 1001 8009 1001 8010 1001 8011

1002 8006 1002 8007 1002 8008 1002 8009 1002 8010 1002 8011

1003 8006 1003 8007 1003 8008 1003 8009 1003 8010 1003 8011

1004 8006 1004 8007 1004 8008 1004 8009 1004 8010 1004 8011

1005 8006 1005 8007 1005 8008 1005 8009 1005 8010 1005 8011

1006 8006 1006 8007 1006 8008 1006 8009 1006 8010 1006 8011

1007 8006 1007 8007 1007 8008 1007 8009 1007 8010 1007 8011

1008 8006 1008 8007 1008 8008 1008 8009 1008 8010 1008 8011

1009 8006 1009 8007 1009 8008 1009 8009 1009 8010 1009 8011

1010 8006 1010 8007 1010 8008 1010 8009 1010 8010 1010 8011

1011 8006 1011 8007 1011 8008 1011 8009 1011 8010 1011 8011

1012 8006 1012 8007 1012 8008 1012 8009 1012 8010 1012 8011

1013 8006 1013 8007 1013 8008 1013 8009 1013 8010 1013 8011

1014 8006 1014 8007 1014 8008 1014 8009 1014 8010 1014 8011

2001 8006 2001 8007 2001 8008 2001 8009 2001 8010 2001 8011

2002 8006 2002 8007 2002 8008 2002 8009 2002 8010 2002 8011

2003 8006 2003 8007 2003 8008 2003 8009 2003 8010 2003 8011

2004 8006 2004 8007 2004 8008 2004 8009 2004 8010 2004 8011

2005 8006 2005 8007 2005 8008 2005 8009 2005 8010 2005 8011

2006 8006 2006 8007 2006 8008 2006 8009 2006 8010 2006 8011

2007 8006 2007 8007 2007 8008 2007 8009 2007 8010 2007 8011

2008 8006 2008 8007 2008 8008 2008 8009 2008 8010 2008 8011

2009 8006 2009 8007 2009 8008 2009 8009 2009 8010 2009 8011

2010 8006 2010 8007 2010 8008 2010 8009 2010 8010 2010 8011

3001 8006 3001 8007 3001 8008 3001 8009 3001 8010 3001 8011

3002 8006 3002 8007 3002 8008 3002 8009 3002 8010 3002 8011

3003 8006 3003 8007 3003 8008 3003 8009 3003 8010 3003 8011

3004 8006 3004 8007 3004 8008 3004 8009 3004 8010 3004 8011

3005 8006 3005 8007 3005 8008 3005 8009 3005 8010 3005 8011

3006 8006 3006 8007 3006 8008 3006 8009 3006 8010 3006 8011

3007 8006 3007 8007 3007 8008 3007 8009 3007 8010 3007 8011

3008 8006 3008 8007 3008 8008 3008 8009 3008 8010 3008 8011

4001 8006 4001 8007 4001 8008 4001 8009 4001 8010 4001 8011

4002 8006 4002 8007 4002 8008 4002 8009 4002 8010 4002 8011

4003 8006 4003 8007 4003 8008 4003 8009 4003 8010 4003 8011

4004 8006 4004 8007 4004 8008 4004 8009 4004 8010 4004 8011

4005 8006 4005 8007 4005 8008 4005 8009 4005 8010 4005 8011

5001 8006 5001 8007 5001 8008 5001 8009 5001 8010 5001 8011

5002 8006 5002 8007 5002 8008 5002 8009 5002 8010 5002 8011 X Y X Y X Υ X Υ X Υ X : Υ

1001 8012 1001 8013 1001 8014 1001 8015 1001 8016

1002 8012 1002 8013 1002 8014 1002 8015 1002 8016

1003 8012 1003 8013 1003 8014 1003 8015 1003 8016

1004 8012 1004 8013 1004 8014 1004 8015 1004 8016

1005 8012 1005 8013 1005 8014 1005 8015 1005 8016

1006 8012 1006 8013 1006 8014 1006 8015 1006 8016

1007 8012 1007 8013 1007 8014 1007 8015 1007 8016

1008 8012 1008 8013 1008 8014 1008 8015 1008 8016

1009 8012 1009 8013 1009 8014 1009 8015 1009 8016

1010 8012 1010 8013 1010 8014 1010 8015 1010 8016

1011 8012 1011 8013 1011 8014 1011 8015 1011 8016

1012 8012 1012 8013 1012 8014 1012 8015 1012 8016

1013 8012 1013 8013 1013 8014 1013 8015 1013 8016

1014 8012 1014 8013 1014 8014 1014 8015 1014 8016

2001 8012 2001 8013 2001 8014 2001 8015 2001 8016

2002 8012 2002 8013 2002 8014 2002 8015 2002 8016

2003 8012 2003 8013 2003 8014 2003 8015 2003 8016

2004 8012 2004 8013 2004 8014 2004 8015 2004 8016

2005 8012 2005 8013 2005 8014 2005 8015 2005 8016

2006 8012 2006 8013 2006 8014 2006 8015 2006 8016 —

2007 8012 2007 8013 2007 8014 2007 8015 2007 8016

2008 8012 2008 8013 2008 8014 2008 8015 2008 8016

2009 8012 2009 8013 2009 8014 2009 8015 2009 8016

2010 8012 2010 8013 2010 8014 2010 8015 2010 8016

3001 8012 3001 8013 3001 8014 3001 8015 3001 8016

3002 8012 3002 8013 3002 8014 3002 8015 3002 8016

3003 8012 3003 8013 3003 8014 3003 8015 3003 8016

3004 8012 3004 8013 3004 8014 3004 8015 3004 8016

3005 8012 3005 8013 3005 8014 3005 8015 3005 8016

3006 8012 3006 8013 3006 8014 3006 8015 3006 8016

3007 8012 3007 8013 3007 8014 3007 8015 3007 8016

3008 8012 3008 8013 3008 8014 3008 8015 3008 8016

4001 8012 4001 8013 4001 8014 4001 8015 4001 8016

4002 8012 4002 8013 4002 8014 4002 8015 4002 8016

4003 8012 4003 8013 4003 8014 4003 8015 4003 8016

4004 8012 4004 8013 4004 8014 4004 8015 4004 8016

4005 8012 4005 8013 4005 8014 4005 8015 4005 8016

5001 8012 5001 8013 5001 8014 5001 8015 5001 8016

5002 8012 5002 8013 5002 8014 5002 8015 5002 8016 Table B: Example combinations of a compound X with a compound Y.

X Y X Y X Y X Y X Y X Y

8000 7000 8000 7041 8001 7000 8001 7041 8002 7000 8002 7041

8000 7001 8000 7042 8001 7001 8001 7042 8002 7001 8002 7042

8000 7002 8000 7043 8001 7002 8001 7043 8002 7002 8002 7043

8000 7003 8000 7044 8001 7003 8001 7044 8002 7003 8002 7044

8000 7004 8000 7045 8001 7004 8001 7045 8002 7004 8002 7045

8000 7005 8000 7046 8001 7005 8001 7046 8002 7005 8002 7046

8000 7006 8000 7047 8001 7006 8001 7047 8002 7006 8002 7047

8000 7007 8000 7048 8001 7007 8001 7048 8002 7007 8002 7048

8000 7008 8000 7049 8001 7008 8001 7049 8002 7008 8002 7049

8000 7009 8000 7050 8001 7009 8001 7050 8002 7009 8002 7050

8000 7010 8000 7051 8001 7010 8001 7051 8002 7010 8002 7051

8000 7011 8000 7052 8001 7011 8001 7052 8002 7011 8002 7052

8000 7012 8000 7053 8001 7012 8001 7053 8002 7012 8002 7053

8000 7013 8000 7054 8001 7013 8001 7054 8002 7013 8002 7054

8000 7014 8000 7055 8001 7014 8001 7055 8002 7014 8002 7055

8000 7015 8000 7056 8001 7015 8001 7056 8002 7015 8002 7056

8000 7016 8000 7057 8001 7016 8001 7057 8002 7016 8002 7057

8000 7017 8000 7058 8001 7017 8001 7058 8002 7017 8002 7058

8000 7018 8000 7059 8001 7018 8001 7059 8002 7018 8002 7059

8000 7019 8000 7060 8001 7019 8001 7060 8002 7019 8002 7060

8000 7020 8000 7061 8001 7020 8001 7061 8002 7020 8002 7061

8000 7021 8000 7062 8001 7021 8001 7062 8002 7021 8002 7062

8000 7022 8000 7063 8001 7022 8001 7063 8002 7022 8002 7063

8000 7023 8000 7064 8001 7023 8001 7064 8002 7023 8002 7064

8000 7024 8000 7065 8001 7024 8001 7065 8002 7024 8002 7065

8000 7025 8000 7066 8001 7025 8001 7066 8002 7025 8002 7066

8000 7026 8000 7067 8001 7026 8001 7067 8002 7026 8002 7067

8000 7027 8000 7068 8001 7027 8001 7068 8002 7027 8002 7068

8000 7028 8000 7069 8001 7028 8001 7069 8002 7028 8002 7069

8000 7029 8000 7070 8001 7029 8001 7070 8002 7029 8002 7070

8000 7030 8000 7071 8001 7030 8001 7071 8002 7030 8002 7071

8000 7031 8000 7072 8001 7031 8001 7072 8002 7031 8002 7072

8000 7032 8000 7073 8001 7032 8001 7073 8002 7032 8002 7073

8000 7033 8000 7074 8001 7033 8001 7074 8002 7033 8002 7074

8000 7034 8000 7075 8001 7034 8001 7075 8002 7034 8002 7075

8000 7035 8000 7076 8001 7035 8001 7076 8002 7035 8002 7076

8000 7036 8000 7077 8001 7036 8001 7077 8002 7036 8002 7077

8000 7037 8001 7037 8002 7037

8000 7038 8001 7038 8002 7038

8000 7039 8001 7039 8002 7039

8000 7040 8001 7040 8002 7040 X Y X Y X Υ X Υ X Υ X Υ

8003 7000 8003 7042 8004 7000 8004 7042 8005 7000 8005 7042

8003 7001 8003 7043 8004 7001 8004 7043 8005 7001 8005 7043

8003 7002 8003 7044 8004 7002 8004 7044 8005 7002 8005 7044

8003 7003 8003 7045 8004 7003 8004 7045 8005 7003 8005 7045

8003 7004 8003 7046 8004 7004 8004 7046 8005 7004 8005 7046

8003 7005 8003 7047 8004 7005 8004 7047 8005 7005 8005 7047

8003 7006 8003 7048 8004 7006 8004 7048 8005 7006 8005 7048

8003 7007 8003 7049 8004 7007 8004 7049 8005 7007 8005 7049

8003 7008 8003 7050 8004 7008 8004 7050 8005 7008 8005 7050

8003 7009 8003 7051 8004 7009 8004 7051 8005 7009 8005 7051

8003 7010 8003 7052 8004 7010 8004 7052 8005 7010 8005 7052

8003 7011 8003 7053 8004 7011 8004 7053 8005 7011 8005 7053

8003 7012 8003 7054 8004 7012 8004 7054 8005 7012 8005 7054

8003 7013 8003 7055 8004 7013 8004 7055 8005 7013 8005 7055

8003 7014 8003 7056 8004 7014 8004 7056 8005 7014 8005 7056

8003 7015 8003 7057 8004 7015 8004 7057 8005 7015 8005 7057

8003 7016 8003 7058 8004 7016 8004 7058 8005 7016 8005 7058

8003 7017 8003 7059 8004 7017 8004 7059 8005 7017 8005 7059

8003 7018 8003 7060 8004 7018 8004 7060 8005 7018 8005 7060

8003 7019 8003 7061 8004 7019 8004 7061 8005 7019 8005 7061

8003 7020 8003 7062 8004 7020 8004 7062 8005 7020 8005 7062

8003 7021 8003 7063 8004 7021 8004 7063 8005 7021 8005 7063

8003 7022 8003 7064 8004 7022 8004 7064 8005 7022 8005 7064

8003 7023 8003 7065 8004 7023 8004 7065 8005 7023 8005 7065

8003 7024 8003 7066 8004 7024 8004 7066 8005 7024 8005 7066

8003 7025 8003 7067 8004 7025 8004 7067 8005 7025 8005 7067

8003 7026 8003 7068 8004 7026 8004 7068 8005 7026 8005 7068

8003 7027 8003 7069 8004 7027 8004 7069 8005 7027 8005 7069

8003 7028 8003 7070 8004 7028 8004 7070 8005 7028 8005 7070

8003 7029 8003 7071 8004 7029 8004 7071 8005 7029 8005 7071

8003 7030 8003 7072 8004 7030 8004 7072 8005 7030 8005 7072

8003 7031 8003 7073 8004 7031 8004 7073 8005 7031 8005 7073

8003 7032 8003 7074 8004 7032 8004 7074 8005 7032 8005 7074

8003 7033 8003 7075 8004 7033 8004 7075 8005 7033 8005 7075

8003 7034 8003 7076 8004 7034 8004 7076 8005 7034 8005 7076

8003 7035 8003 7077 8004 7035 8004 7077 8005 7035 8005 7077

8003 7036 8004 7036 8005 7036

8003 7037 8004 7037 8005 7037

8003 7038 8004 7038 8005 7038

8003 7039 8004 7039 8005 7039

8003 7040 8004 7040 8005 7040

8003 7041 8004 7041 8005 7041 X Y X Y X Υ X Υ X Υ X Υ

8006 7000 8006 7042 8007 7000 8007 7042 8008 7000 8008 7042

8006 7001 8006 7043 8007 7001 8007 7043 8008 7001 8008 7043

8006 7002 8006 7044 8007 7002 8007 7044 8008 7002 8008 7044

8006 7003 8006 7045 8007 7003 8007 7045 8008 7003 8008 7045

8006 7004 8006 7046 8007 7004 8007 7046 8008 7004 8008 7046

8006 7005 8006 7047 8007 7005 8007 7047 8008 7005 8008 7047

8006 7006 8006 7048 8007 7006 8007 7048 8008 7006 8008 7048

8006 7007 8006 7049 8007 7007 8007 7049 8008 7007 8008 7049

8006 7008 8006 7050 8007 7008 8007 7050 8008 7008 8008 7050

8006 7009 8006 7051 8007 7009 8007 7051 8008 7009 8008 7051

8006 7010 8006 7052 8007 7010 8007 7052 8008 7010 8008 7052

8006 7011 8006 7053 8007 7011 8007 7053 8008 7011 8008 7053

8006 7012 8006 7054 8007 7012 8007 7054 8008 7012 8008 7054

8006 7013 8006 7055 8007 7013 8007 7055 8008 7013 8008 7055

8006 7014 8006 7056 8007 7014 8007 7056 8008 7014 8008 7056

8006 7015 8006 7057 8007 7015 8007 7057 8008 7015 8008 7057

8006 7016 8006 7058 8007 7016 8007 7058 8008 7016 8008 7058

8006 7017 8006 7059 8007 7017 8007 7059 8008 7017 8008 7059

8006 7018 8006 7060 8007 7018 8007 7060 8008 7018 8008 7060

8006 7019 8006 7061 8007 7019 8007 7061 8008 7019 8008 7061

8006 7020 8006 7062 8007 7020 8007 7062 8008 7020 8008 7062

8006 7021 8006 7063 8007 7021 8007 7063 8008 7021 8008 7063

8006 7022 8006 7064 8007 7022 8007 7064 8008 7022 8008 7064

8006 7023 8006 7065 8007 7023 8007 7065 8008 7023 8008 7065

8006 7024 8006 7066 8007 7024 8007 7066 8008 7024 8008 7066

8006 7025 8006 7067 8007 7025 8007 7067 8008 7025 8008 7067

8006 7026 8006 7068 8007 7026 8007 7068 8008 7026 8008 7068

8006 7027 8006 7069 8007 7027 8007 7069 8008 7027 8008 7069

8006 7028 8006 7070 8007 7028 8007 7070 8008 7028 8008 7070

8006 7029 8006 7071 8007 7029 8007 7071 8008 7029 8008 7071

8006 7030 8006 7072 8007 7030 8007 7072 8008 7030 8008 7072

8006 7031 8006 7073 8007 7031 8007 7073 8008 7031 8008 7073

8006 7032 8006 7074 8007 7032 8007 7074 8008 7032 8008 7074

8006 7033 8006 7075 8007 7033 8007 7075 8008 7033 8008 7075

8006 7034 8006 7076 8007 7034 8007 7076 8008 7034 8008 7076

8006 7035 8006 7077 8007 7035 8007 7077 8008 7035 8008 7077

8006 7036 8007 7036 8008 7036

8006 7037 8007 7037 8008 7037

8006 7038 8007 7038 8008 7038

8006 7039 8007 7039 8008 7039

8006 7040 8007 7040 8008 7040

8006 7041 8007 7041 8008 7041 X Y X Y X Υ X Υ X Υ X Υ

8009 7000 8009 7042 8010 7000 8010 7042 8011 7000 8011 7042

8009 7001 8009 7043 8010 7001 8010 7043 8011 7001 8011 7043

8009 7002 8009 7044 8010 7002 8010 7044 8011 7002 8011 7044

8009 7003 8009 7045 8010 7003 8010 7045 8011 7003 8011 7045

8009 7004 8009 7046 8010 7004 8010 7046 8011 7004 8011 7046

8009 7005 8009 7047 8010 7005 8010 7047 8011 7005 8011 7047

8009 7006 8009 7048 8010 7006 8010 7048 8011 7006 8011 7048

8009 7007 8009 7049 8010 7007 8010 7049 8011 7007 8011 7049

8009 7008 8009 7050 8010 7008 8010 7050 8011 7008 8011 7050

8009 7009 8009 7051 8010 7009 8010 7051 8011 7009 8011 7051

8009 7010 8009 7052 8010 7010 8010 7052 8011 7010 8011 7052

8009 7011 8009 7053 8010 7011 8010 7053 8011 7011 8011 7053

8009 7012 8009 7054 8010 7012 8010 7054 8011 7012 8011 7054

8009 7013 8009 7055 8010 7013 8010 7055 8011 7013 8011 7055

8009 7014 8009 7056 8010 7014 8010 7056 8011 7014 8011 7056

8009 7015 8009 7057 8010 7015 8010 7057 8011 7015 8011 7057

8009 7016 8009 7058 8010 7016 8010 7058 8011 7016 8011 7058

8009 7017 8009 7059 8010 7017 8010 7059 8011 7017 8011 7059

8009 7018 8009 7060 8010 7018 8010 7060 8011 7018 8011 7060

8009 7019 8009 7061 8010 7019 8010 7061 8011 7019 8011 7061

8009 7020 8009 7062 8010 7020 8010 7062 8011 7020 8011 7062

8009 7021 8009 7063 8010 7021 8010 7063 8011 7021 8011 7063

8009 7022 8009 7064 8010 7022 8010 7064 8011 7022 8011 7064

8009 7023 8009 7065 8010 7023 8010 7065 8011 7023 8011 7065

8009 7024 8009 7066 8010 7024 8010 7066 8011 7024 8011 7066

8009 7025 8009 7067 8010 7025 8010 7067 8011 7025 8011 7067

8009 7026 8009 7068 8010 7026 8010 7068 8011 7026 8011 7068

8009 7027 8009 7069 8010 7027 8010 7069 8011 7027 8011 7069

8009 7028 8009 7070 8010 7028 8010 7070 8011 7028 8011 7070

8009 7029 8009 7071 8010 7029 8010 7071 8011 7029 8011 7071

8009 7030 8009 7072 8010 7030 8010 7072 8011 7030 8011 7072

8009 7031 8009 7073 8010 7031 8010 7073 8011 7031 8011 7073

8009 7032 8009 7074 8010 7032 8010 7074 8011 7032 8011 7074

8009 7033 8009 7075 8010 7033 8010 7075 8011 7033 8011 7075

8009 7034 8009 7076 8010 7034 8010 7076 8011 7034 8011 7076

8009 7035 8009 7077 8010 7035 8010 7077 8011 7035 8011 7077

8009 7036 8010 7036 8011 7036

8009 7037 8010 7037 8011 7037

8009 7038 8010 7038 8011 7038

8009 7039 8010 7039 8011 7039

8009 7040 8010 7040 8011 7040

8009 7041 8010 7041 8011 7041 X Y X Y X Υ X Υ X Υ X Υ

8012 7000 8012 7042 8013 7000 8013 7042 8014 7000 8014 7042

8012 7001 8012 7043 8013 7001 8013 7043 8014 7001 8014 7043

8012 7002 8012 7044 8013 7002 8013 7044 8014 7002 8014 7044

8012 7003 8012 7045 8013 7003 8013 7045 8014 7003 8014 7045

8012 7004 8012 7046 8013 7004 8013 7046 8014 7004 8014 7046

8012 7005 8012 7047 8013 7005 8013 7047 8014 7005 8014 7047

8012 7006 8012 7048 8013 7006 8013 7048 8014 7006 8014 7048

8012 7007 8012 7049 8013 7007 8013 7049 8014 7007 8014 7049

8012 7008 8012 7050 8013 7008 8013 7050 8014 7008 8014 7050

8012 7009 8012 7051 8013 7009 8013 7051 8014 7009 8014 7051

8012 7010 8012 7052 8013 7010 8013 7052 8014 7010 8014 7052

8012 7011 8012 7053 8013 7011 8013 7053 8014 7011 8014 7053

8012 7012 8012 7054 8013 7012 8013 7054 8014 7012 8014 7054

8012 7013 8012 7055 8013 7013 8013 7055 8014 7013 8014 7055

8012 7014 8012 7056 8013 7014 8013 7056 8014 7014 8014 7056

8012 7015 8012 7057 8013 7015 8013 7057 8014 7015 8014 7057

8012 7016 8012 7058 8013 7016 8013 7058 8014 7016 8014 7058

8012 7017 8012 7059 8013 7017 8013 7059 8014 7017 8014 7059

8012 7018 8012 7060 8013 7018 8013 7060 8014 7018 8014 7060

8012 7019 8012 7061 8013 7019 8013 7061 8014 7019 8014 7061

8012 7020 8012 7062 8013 7020 8013 7062 8014 7020 8014 7062

8012 7021 8012 7063 8013 7021 8013 7063 8014 7021 8014 7063

8012 7022 8012 7064 8013 7022 8013 7064 8014 7022 8014 7064

8012 7023 8012 7065 8013 7023 8013 7065 8014 7023 8014 7065

8012 7024 8012 7066 8013 7024 8013 7066 8014 7024 8014 7066

8012 7025 8012 7067 8013 7025 8013 7067 8014 7025 8014 7067

8012 7026 8012 7068 8013 7026 8013 7068 8014 7026 8014 7068

8012 7027 8012 7069 8013 7027 8013 7069 8014 7027 8014 7069

8012 7028 8012 7070 8013 7028 8013 7070 8014 7028 8014 7070

8012 7029 8012 7071 8013 7029 8013 7071 8014 7029 8014 7071

8012 7030 8012 7072 8013 7030 8013 7072 8014 7030 8014 7072

8012 7031 8012 7073 8013 7031 8013 7073 8014 7031 8014 7073

8012 7032 8012 7074 8013 7032 8013 7074 8014 7032 8014 7074

8012 7033 8012 7075 8013 7033 8013 7075 8014 7033 8014 7075

8012 7034 8012 7076 8013 7034 8013 7076 8014 7034 8014 7076

8012 7035 8012 7077 8013 7035 8013 7077 8014 7035 8014 7077

8012 7036 8013 7036 8014 7036

8012 7037 8013 7037 8014 7037

8012 7038 8013 7038 8014 7038

8012 7039 8013 7039 8014 7039

8012 7040 8013 7040 8014 7040

8012 7041 8013 7041 8014 7041 X Y X Y X Υ X Υ X : Υ X : Υ

8015 7000 8015 7042 8016 7000 8016 7042

8015 7001 8015 7043 8016 7001 8016 7043

8015 7002 8015 7044 8016 7002 8016 7044

8015 7003 8015 7045 8016 7003 8016 7045

8015 7004 8015 7046 8016 7004 8016 7046

8015 7005 8015 7047 8016 7005 8016 7047

8015 7006 8015 7048 8016 7006 8016 7048

8015 7007 8015 7049 8016 7007 8016 7049

8015 7008 8015 7050 8016 7008 8016 7050

8015 7009 8015 7051 8016 7009 8016 7051

8015 7010 8015 7052 8016 7010 8016 7052

8015 7011 8015 7053 8016 7011 8016 7053

8015 7012 8015 7054 8016 7012 8016 7054

8015 7013 8015 7055 8016 7013 8016 7055

8015 7014 8015 7056 8016 7014 8016 7056

8015 7015 8015 7057 8016 7015 8016 7057

8015 7016 8015 7058 8016 7016 8016 7058

8015 7017 8015 7059 8016 7017 8016 7059

8015 7018 8015 7060 8016 7018 8016 7060

8015 7019 8015 7061 8016 7019 8016 7061

8015 7020 8015 7062 8016 7020 8016 7062

8015 7021 8015 7063 8016 7021 8016 7063

8015 7022 8015 7064 8016 7022 8016 7064

8015 7023 8015 7065 8016 7023 8016 7065

8015 7024 8015 7066 8016 7024 8016 7066

8015 7025 8015 7067 8016 7025 8016 7067

8015 7026 8015 7068 8016 7026 8016 7068

8015 7027 8015 7069 8016 7027 8016 7069

8015 7028 8015 7070 8016 7028 8016 7070

8015 7029 8015 7071 8016 7029 8016 7071

8015 7030 8015 7072 8016 7030 8016 7072

8015 7031 8015 7073 8016 7031 8016 7073

8015 7032 8015 7074 8016 7032 8016 7074

8015 7033 8015 7075 8016 7033 8016 7075

8015 7034 8015 7076 8016 7034 8016 7076

8015 7035 8015 7077 8016 7035 8016 7077

8015 7036 8016 7036

8015 7037 8016 7037

8015 7038 8016 7038

8015 7039 8016 7039

8015 7040 8016 7040

8015 7041 8016 7041 Table C: Example combinations of a compound X with a compound Y.

X Y X Y X Y X Y X Y X Y

6000 8000 6043 8000 6000 8001 6043 8001 6000 8002 6043 8002

6001 8000 6044 8000 6001 8001 6044 8001 6001 8002 6044 8002

6002 8000 6045 8000 6002 8001 6045 8001 6002 8002 6045 8002

6003 8000 6046 8000 6003 8001 6046 8001 6003 8002 6046 8002

6004 8000 6047 8000 6004 8001 6047 8001 6004 8002 6047 8002

6005 8000 6048 8000 6005 8001 6048 8001 6005 8002 6048 8002

6006 8000 6049 8000 6006 8001 6049 8001 6006 8002 6049 8002

6007 8000 6050 8000 6007 8001 6050 8001 6007 8002 6050 8002

6008 8000 6051 8000 6008 8001 6051 8001 6008 8002 6051 8002

6009 8000 6052 8000 6009 8001 6052 8001 6009 8002 6052 8002

6010 8000 6053 8000 6010 8001 6053 8001 6010 8002 6053 8002

6011 8000 6054 8000 6011 8001 6054 8001 6011 8002 6054 8002

6012 8000 6055 8000 6012 8001 6055 8001 6012 8002 6055 8002

6013 8000 6056 8000 6013 8001 6056 8001 6013 8002 6056 8002

6014 8000 6057 8000 6014 8001 6057 8001 6014 8002 6057 8002

6015 8000 6058 8000 6015 8001 6058 8001 6015 8002 6058 8002

6016 8000 6059 8000 6016 8001 6059 8001 6016 8002 6059 8002

6017 8000 6060 8000 6017 8001 6060 8001 6017 8002 6060 8002

6018 8000 6061 8000 6018 8001 6061 8001 6018 8002 6061 8002

6019 8000 6062 8000 6019 8001 6062 8001 6019 8002 6062 8002

6020 8000 6063 8000 6020 8001 6063 8001 6020 8002 6063 8002

6021 8000 6064 8000 6021 8001 6064 8001 6021 8002 6064 8002

6022 8000 6065 8000 6022 8001 6065 8001 6022 8002 6065 8002

6023 8000 6066 8000 6023 8001 6066 8001 6023 8002 6066 8002

6024 8000 6067 8000 6024 8001 6067 8001 6024 8002 6067 8002

6025 8000 6068 8000 6025 8001 6068 8001 6025 8002 6068 8002

6026 8000 6069 8000 6026 8001 6069 8001 6026 8002 6069 8002

6027 8000 6070 8000 6027 8001 6070 8001 6027 8002 6070 8002

6028 8000 6071 8000 6028 8001 6071 8001 6028 8002 6071 8002

6029 8000 6072 8000 6029 8001 6072 8001 6029 8002 6072 8002

6030 8000 6073 8000 6030 8001 6073 8001 6030 8002 6073 8002

6031 8000 6074 8000 6031 8001 6074 8001 6031 8002 6074 8002

6032 8000 6075 8000 6032 8001 6075 8001 6032 8002 6075 8002

6033 8000 6076 8000 6033 8001 6076 8001 6033 8002 6076 8002

6034 8000 6077 8000 6034 8001 6077 8001 6034 8002 6077 8002

6035 8000 6078 8000 6035 8001 6078 8001 6035 8002 6078 8002

6036 8000 6036 8001 6036 8002

6037 8000 6037 8001 6037 8002

6038 8000 6038 8001 6038 8002

6039 8000 6039 8001 6039 8002

6040 8000 6040 8001 6040 8002

6041 8000 6041 8001 6041 8002

6042 8000 6042 8001 6042 8002 X Y X Y X Υ X Υ X Υ X Υ

6000 8003 6043 8003 6000 8004 6043 8004 6000 8005 6043 8005

6001 8003 6044 8003 6001 8004 6044 8004 6001 8005 6044 8005

6002 8003 6045 8003 6002 8004 6045 8004 6002 8005 6045 8005

6003 8003 6046 8003 6003 8004 6046 8004 6003 8005 6046 8005

6004 8003 6047 8003 6004 8004 6047 8004 6004 8005 6047 8005

6005 8003 6048 8003 6005 8004 6048 8004 6005 8005 6048 8005

6006 8003 6049 8003 6006 8004 6049 8004 6006 8005 6049 8005

6007 8003 6050 8003 6007 8004 6050 8004 6007 8005 6050 8005

6008 8003 6051 8003 6008 8004 6051 8004 6008 8005 6051 8005

6009 8003 6052 8003 6009 8004 6052 8004 6009 8005 6052 8005

6010 8003 6053 8003 6010 8004 6053 8004 6010 8005 6053 8005

6011 8003 6054 8003 6011 8004 6054 8004 6011 8005 6054 8005

6012 8003 6055 8003 6012 8004 6055 8004 6012 8005 6055 8005

6013 8003 6056 8003 6013 8004 6056 8004 6013 8005 6056 8005

6014 8003 6057 8003 6014 8004 6057 8004 6014 8005 6057 8005

6015 8003 6058 8003 6015 8004 6058 8004 6015 8005 6058 8005

6016 8003 6059 8003 6016 8004 6059 8004 6016 8005 6059 8005

6017 8003 6060 8003 6017 8004 6060 8004 6017 8005 6060 8005

6018 8003 6061 8003 6018 8004 6061 8004 6018 8005 6061 8005

6019 8003 6062 8003 6019 8004 6062 8004 6019 8005 6062 8005

6020 8003 6063 8003 6020 8004 6063 8004 6020 8005 6063 8005

6021 8003 6064 8003 6021 8004 6064 8004 6021 8005 6064 8005

6022 8003 6065 8003 6022 8004 6065 8004 6022 8005 6065 8005

6023 8003 6066 8003 6023 8004 6066 8004 6023 8005 6066 8005

6024 8003 6067 8003 6024 8004 6067 8004 6024 8005 6067 8005

6025 8003 6068 8003 6025 8004 6068 8004 6025 8005 6068 8005

6026 8003 6069 8003 6026 8004 6069 8004 6026 8005 6069 8005

6027 8003 6070 8003 6027 8004 6070 8004 6027 8005 6070 8005

6028 8003 6071 8003 6028 8004 6071 8004 6028 8005 6071 8005

6029 8003 6072 8003 6029 8004 6072 8004 6029 8005 6072 8005

6030 8003 6073 8003 6030 8004 6073 8004 6030 8005 6073 8005

6031 8003 6074 8003 6031 8004 6074 8004 6031 8005 6074 8005

6032 8003 6075 8003 6032 8004 6075 8004 6032 8005 6075 8005

6033 8003 6076 8003 6033 8004 6076 8004 6033 8005 6076 8005

6034 8003 6077 8003 6034 8004 6077 8004 6034 8005 6077 8005

6035 8003 6078 8003 6035 8004 6078 8004 6035 8005 6078 8005

6036 8003 6036 8004 6036 8005

6037 8003 6037 8004 6037 8005

6038 8003 6038 8004 6038 8005

6039 8003 6039 8004 6039 8005

6040 8003 6040 8004 6040 8005

6041 8003 6041 8004 6041 8005

6042 8003 6042 8004 6042 8005 X Y X Y X Υ X Υ X Υ X Υ

6000 8006 6043 8006 6000 8007 6043 8007 6000 8008 6043 8008

6001 8006 6044 8006 6001 8007 6044 8007 6001 8008 6044 8008

6002 8006 6045 8006 6002 8007 6045 8007 6002 8008 6045 8008

6003 8006 6046 8006 6003 8007 6046 8007 6003 8008 6046 8008

6004 8006 6047 8006 6004 8007 6047 8007 6004 8008 6047 8008

6005 8006 6048 8006 6005 8007 6048 8007 6005 8008 6048 8008

6006 8006 6049 8006 6006 8007 6049 8007 6006 8008 6049 8008

6007 8006 6050 8006 6007 8007 6050 8007 6007 8008 6050 8008

6008 8006 6051 8006 6008 8007 6051 8007 6008 8008 6051 8008

6009 8006 6052 8006 6009 8007 6052 8007 6009 8008 6052 8008

6010 8006 6053 8006 6010 8007 6053 8007 6010 8008 6053 8008

6011 8006 6054 8006 6011 8007 6054 8007 6011 8008 6054 8008

6012 8006 6055 8006 6012 8007 6055 8007 6012 8008 6055 8008

6013 8006 6056 8006 6013 8007 6056 8007 6013 8008 6056 8008

6014 8006 6057 8006 6014 8007 6057 8007 6014 8008 6057 8008

6015 8006 6058 8006 6015 8007 6058 8007 6015 8008 6058 8008

6016 8006 6059 8006 6016 8007 6059 8007 6016 8008 6059 8008

6017 8006 6060 8006 6017 8007 6060 8007 6017 8008 6060 8008

6018 8006 6061 8006 6018 8007 6061 8007 6018 8008 6061 8008

6019 8006 6062 8006 6019 8007 6062 8007 6019 8008 6062 8008

6020 8006 6063 8006 6020 8007 6063 8007 6020 8008 6063 8008

6021 8006 6064 8006 6021 8007 6064 8007 6021 8008 6064 8008

6022 8006 6065 8006 6022 8007 6065 8007 6022 8008 6065 8008

6023 8006 6066 8006 6023 8007 6066 8007 6023 8008 6066 8008

6024 8006 6067 8006 6024 8007 6067 8007 6024 8008 6067 8008

6025 8006 6068 8006 6025 8007 6068 8007 6025 8008 6068 8008

6026 8006 6069 8006 6026 8007 6069 8007 6026 8008 6069 8008

6027 8006 6070 8006 6027 8007 6070 8007 6027 8008 6070 8008

6028 8006 6071 8006 6028 8007 6071 8007 6028 8008 6071 8008

6029 8006 6072 8006 6029 8007 6072 8007 6029 8008 6072 8008

6030 8006 6073 8006 6030 8007 6073 8007 6030 8008 6073 8008

6031 8006 6074 8006 6031 8007 6074 8007 6031 8008 6074 8008

6032 8006 6075 8006 6032 8007 6075 8007 6032 8008 6075 8008

6033 8006 6076 8006 6033 8007 6076 8007 6033 8008 6076 8008

6034 8006 6077 8006 6034 8007 6077 8007 6034 8008 6077 8008

6035 8006 6078 8006 6035 8007 6078 8007 6035 8008 6078 8008

6036 8006 6036 8007 6036 8008

6037 8006 6037 8007 6037 8008

6038 8006 6038 8007 6038 8008

6039 8006 6039 8007 6039 8008

6040 8006 6040 8007 6040 8008

6041 8006 6041 8007 6041 8008

6042 8006 6042 8007 6042 8008 Table D: Example combinations of a compound X with a compound Y.

X Y X Y X Y X Y X Y X Y

6000 8009 6043 8009 6000 8010 6043 8010 6000 8011 6043 8011

6001 8009 6044 8009 6001 8010 6044 8010 6001 8011 6044 8011

6002 8009 6045 8009 6002 8010 6045 8010 6002 8011 6045 8011

6003 8009 6046 8009 6003 8010 6046 8010 6003 8011 6046 8011

6004 8009 6047 8009 6004 8010 6047 8010 6004 8011 6047 8011

6005 8009 6048 8009 6005 8010 6048 8010 6005 8011 6048 8011

6006 8009 6049 8009 6006 8010 6049 8010 6006 8011 6049 8011

6007 8009 6050 8009 6007 8010 6050 8010 6007 8011 6050 8011

6008 8009 6051 8009 6008 8010 6051 8010 6008 8011 6051 8011

6009 8009 6052 8009 6009 8010 6052 8010 6009 8011 6052 8011

6010 8009 6053 8009 6010 8010 6053 8010 6010 8011 6053 8011

6011 8009 6054 8009 6011 8010 6054 8010 6011 8011 6054 8011

6012 8009 6055 8009 6012 8010 6055 8010 6012 8011 6055 8011

6013 8009 6056 8009 6013 8010 6056 8010 6013 8011 6056 8011

6014 8009 6057 8009 6014 8010 6057 8010 6014 8011 6057 8011

6015 8009 6058 8009 6015 8010 6058 8010 6015 8011 6058 8011

6016 8009 6059 8009 6016 8010 6059 8010 6016 8011 6059 8011

6017 8009 6060 8009 6017 8010 6060 8010 6017 8011 6060 8011

6018 8009 6061 8009 6018 8010 6061 8010 6018 8011 6061 8011

6019 8009 6062 8009 6019 8010 6062 8010 6019 8011 6062 8011

6020 8009 6063 8009 6020 8010 6063 8010 6020 8011 6063 8011

6021 8009 6064 8009 6021 8010 6064 8010 6021 8011 6064 8011

6022 8009 6065 8009 6022 8010 6065 8010 6022 8011 6065 8011

6023 8009 6066 8009 6023 8010 6066 8010 6023 8011 6066 8011

6024 8009 6067 8009 6024 8010 6067 8010 6024 8011 6067 8011

6025 8009 6068 8009 6025 8010 6068 8010 6025 8011 6068 8011

6026 8009 6069 8009 6026 8010 6069 8010 6026 8011 6069 8011

6027 8009 6070 8009 6027 8010 6070 8010 6027 8011 6070 8011

6028 8009 6071 8009 6028 8010 6071 8010 6028 8011 6071 8011

6029 8009 6072 8009 6029 8010 6072 8010 6029 8011 6072 8011

6030 8009 6073 8009 6030 8010 6073 8010 6030 8011 6073 8011

6031 8009 6074 8009 6031 8010 6074 8010 6031 8011 6074 8011

6032 8009 6075 8009 6032 8010 6075 8010 6032 8011 6075 8011

6033 8009 6076 8009 6033 8010 6076 8010 6033 8011 6076 8011

6034 8009 6077 8009 6034 8010 6077 8010 6034 8011 6077 8011

6035 8009 6078 8009 6035 8010 6078 8010 6035 8011 6078 8011

6036 8009 6036 8010 6036 8011

6037 8009 6037 8010 6037 8011

6038 8009 6038 8010 6038 8011

6039 8009 6039 8010 6039 8011

6040 8009 6040 8010 6040 8011

6041 8009 6041 8010 6041 8011

6042 8009 6042 8010 6042 8011 X Y X Y X Υ X Υ X Υ X Υ

6000 8012 6043 8012 6000 8013 6043 8013 6000 8014 6043 8014

6001 8012 6044 8012 6001 8013 6044 8013 6001 8014 6044 8014

6002 8012 6045 8012 6002 8013 6045 8013 6002 8014 6045 8014

6003 8012 6046 8012 6003 8013 6046 8013 6003 8014 6046 8014

6004 8012 6047 8012 6004 8013 6047 8013 6004 8014 6047 8014

6005 8012 6048 8012 6005 8013 6048 8013 6005 8014 6048 8014

6006 8012 6049 8012 6006 8013 6049 8013 6006 8014 6049 8014

6007 8012 6050 8012 6007 8013 6050 8013 6007 8014 6050 8014

6008 8012 6051 8012 6008 8013 6051 8013 6008 8014 6051 8014

6009 8012 6052 8012 6009 8013 6052 8013 6009 8014 6052 8014

6010 8012 6053 8012 6010 8013 6053 8013 6010 8014 6053 8014

6011 8012 6054 8012 6011 8013 6054 8013 6011 8014 6054 8014

6012 8012 6055 8012 6012 8013 6055 8013 6012 8014 6055 8014

6013 8012 6056 8012 6013 8013 6056 8013 6013 8014 6056 8014

6014 8012 6057 8012 6014 8013 6057 8013 6014 8014 6057 8014

6015 8012 6058 8012 6015 8013 6058 8013 6015 8014 6058 8014

6016 8012 6059 8012 6016 8013 6059 8013 6016 8014 6059 8014

6017 8012 6060 8012 6017 8013 6060 8013 6017 8014 6060 8014

6018 8012 6061 8012 6018 8013 6061 8013 6018 8014 6061 8014

6019 8012 6062 8012 6019 8013 6062 8013 6019 8014 6062 8014

6020 8012 6063 8012 6020 8013 6063 8013 6020 8014 6063 8014

6021 8012 6064 8012 6021 8013 6064 8013 6021 8014 6064 8014

6022 8012 6065 8012 6022 8013 6065 8013 6022 8014 6065 8014

6023 8012 6066 8012 6023 8013 6066 8013 6023 8014 6066 8014

6024 8012 6067 8012 6024 8013 6067 8013 6024 8014 6067 8014

6025 8012 6068 8012 6025 8013 6068 8013 6025 8014 6068 8014

6026 8012 6069 8012 6026 8013 6069 8013 6026 8014 6069 8014

6027 8012 6070 8012 6027 8013 6070 8013 6027 8014 6070 8014

6028 8012 6071 8012 6028 8013 6071 8013 6028 8014 6071 8014

6029 8012 6072 8012 6029 8013 6072 8013 6029 8014 6072 8014

6030 8012 6073 8012 6030 8013 6073 8013 6030 8014 6073 8014

6031 8012 6074 8012 6031 8013 6074 8013 6031 8014 6074 8014

6032 8012 6075 8012 6032 8013 6075 8013 6032 8014 6075 8014

6033 8012 6076 8012 6033 8013 6076 8013 6033 8014 6076 8014

6034 8012 6077 8012 6034 8013 6077 8013 6034 8014 6077 8014

6035 8012 6078 8012 6035 8013 6078 8013 6035 8014 6078 8014

6036 8012 6036 8013 6036 8014

6037 8012 6037 8013 6037 8014

6038 8012 6038 8013 6038 8014

6039 8012 6039 8013 6039 8014

6040 8012 6040 8013 6040 8014

6041 8012 6041 8013 6041 8014

6042 8012 6042 8013 6042 8014 X Y X Y X Υ X Υ X : Υ X : Υ

6000 8015 6043 8015 6000 8016 6043 8016

6001 8015 6044 8015 6001 8016 6044 8016

6002 8015 6045 8015 6002 8016 6045 8016

6003 8015 6046 8015 6003 8016 6046 8016

6004 8015 6047 8015 6004 8016 6047 8016

6005 8015 6048 8015 6005 8016 6048 8016

6006 8015 6049 8015 6006 8016 6049 8016

6007 8015 6050 8015 6007 8016 6050 8016

6008 8015 6051 8015 6008 8016 6051 8016

6009 8015 6052 8015 6009 8016 6052 8016

6010 8015 6053 8015 6010 8016 6053 8016

6011 8015 6054 8015 6011 8016 6054 8016

6012 8015 6055 8015 6012 8016 6055 8016

6013 8015 6056 8015 6013 8016 6056 8016

6014 8015 6057 8015 6014 8016 6057 8016

6015 8015 6058 8015 6015 8016 6058 8016

6016 8015 6059 8015 6016 8016 6059 8016

6017 8015 6060 8015 6017 8016 6060 8016

6018 8015 6061 8015 6018 8016 6061 8016

6019 8015 6062 8015 6019 8016 6062 8016

6020 8015 6063 8015 6020 8016 6063 8016

6021 8015 6064 8015 6021 8016 6064 8016

6022 8015 6065 8015 6022 8016 6065 8016

6023 8015 6066 8015 6023 8016 6066 8016

6024 8015 6067 8015 6024 8016 6067 8016

6025 8015 6068 8015 6025 8016 6068 8016

6026 8015 6069 8015 6026 8016 6069 8016

6027 8015 6070 8015 6027 8016 6070 8016

6028 8015 6071 8015 6028 8016 6071 8016

6029 8015 6072 8015 6029 8016 6072 8016

6030 8015 6073 8015 6030 8016 6073 8016

6031 8015 6074 8015 6031 8016 6074 8016

6032 8015 6075 8015 6032 8016 6075 8016

6033 8015 6076 8015 6033 8016 6076 8016

6034 8015 6077 8015 6034 8016 6077 8016

6035 8015 6078 8015 6035 8016 6078 8016

6036 8015 6036 8016

6037 8015 6037 8016

6038 8015 6038 8016

6039 8015 6039 8016

6040 8015 6040 8016

6041 8015 6041 8016

6042 8015 6042 8016

EXAMPLES

[0209] Additional embodiments are disclosed in further detail in the following examples, which are not in any way intended to limit the scope of the claims. Example 1

(Rp/Sp) 2'-C-methyl-6-0-methyl-guanosine-3',5 ^, -cyclic-0-methyl phosphorothioate (la)

(RP/SP)

Bis[3-(triethoxysilyl)- propyl]tetrasulfide

1a (Rp/Sp)

[0210] Step 1 : Compound of Pl-2 - To a flask containing Pl-1 (20.0 g, 147.3 mmol) was added absolute MeOH (3.78 g, 118 mmol) dropwise over 2 hours at -40°C. The mixture was warmed to room temperature gradually and stirred for another hour. The reaction mixture was distilled to give Pl-2 (9.5 g, 61%). ^X H NMR (CDC1 ₃ , 400 MHz) δ 3.90 (d, J= 10.4 Hz, 3H). ³¹ P NMR (CDC1 ₃ , 162 MHz) δ 180.81.

[0211] Step 2: Compound of Pl-3 - To a solution of Pl-2 (9.5 g, 72.0 mmol) in anhydrous ether (200 mL) was added diisopropylamine (43.5 g, 430.8 mmol) dropwise at 0°C. The mixture was stirred at room temperature overnight. The precipitate was filtered and the filtrate was concentrated to give a residue, which was distilled to give Pl-3 (6.5 g, 34%) as a colorless oil. 1H NMR (CDCI ₃ , 400 MHz) δ 3.42-3.48 (m, 4H), 3.31 (d, J= 14.0 Hz, 3H), 1.02- 1.11 (m, 27H). ³¹ P NMR (CDCI ₃ , 162 MHz) δ 130.99.

[0212] Step 3: Compound la - A 1.0 M solution of 4,5-dicyanoimidazole (DCl) in CH ₃ CN (0.38 mL, 0.38 mmol) was added dropwise into a solution of 2'-C-methyl-6-0-methyl- guanosine (Pl-4) (0.2 g, 0.64 mmol) in CH ₃ CN (10 mL) in N ₂ atmosphere, and stirred at room temperature. After 40 minutes, the reaction mixture was cooled to 0-5 °C using an ice/water bath. A freshly prepared solution of methyl Ν,Ν,Ν',Ν'- tetraisopropylphosphorodiamidite in dichloromethane (DCM) (221 μΐ in 0.7 mL DCM, 0.77 mmol) was added. The reaction mixture was allowed to warm to room temperature and was stirred for 2 hours. Additional DCl (50 mg, 0.42 mmol) was added, and the reaction was stirred for 1 h to give a phosphite intermediate. Bis[3-(triethoxysilyl)propyl]tetrasulfide (0.415 mL, 0.77 mmol) was added dropwise to the reaction mixture and the resultant light yellow suspension was stirred for 2 h at room temperature. The reaction mixture was cooled using an ice/water bath, and then diluted with ethyl acetate (EA) (150 mL), washed with saturated NaHC03 followed by brine, then dried over anhydrous Na ₂ S0 ₄ and concentrated in-vacuo to give a crude product residue which was purified by silica gel (DCM/MeOH; 95:5) to give 37.1 mg as white solid. Further purification by silica gel (DCM/isopropyl alcohol; 94:6) gave 16.9 mg of impure product, which was purified by RP-HPLC (H ₂ 0/ CH ₃ CN; 0 to 50 %, 30 min) to afford compound la (8.6 mg) as a white foam after lyophilization. ^X H NMR (400 MHz, (CD ₃ ) ₂ CO, two isomers): δ 1.13 (s, 3H), 3.86 (2s, 3H), 3.71, 3.76 (2d, J = 13.6 Hz, 3H), 4.36-4.5 (m, 1H), 4.63-4.71 (m, 3H), 5.09, 5.18 (2s, 1H), 5.85-5.87 (br s, 2H), 6.00 (s, 1H), 7.91, 7.95 (2s, 1H); ³¹ P NMR ((CD ₃ ) ₂ CO, two isomers): δ 65.07 (s), 68.4 (s); MS m/z 404.3 (M+H) ⁺ .

EXAMPLE 2

Preparation of 4'-azido-2'-deoxy-2'-fluorouridine 3%5'-cvclic thiophosphoric acid methyl ester (2a)

[0213] To an ice-cold suspension of 4'-azido-2'-deoxy-2'-fluorouridine (150 mg, 0.52 mmol) in dry pyridine (4 mL) was added tetrazole (0.37 M in MeCN, 4 mL, 1.48 mmol), followed by addition of methyl NNN'.N'-tetraisopropylphosphordiamidite (204 mg, 0.78 mmol) dropwise over 5 min. The resultant mixture was stirred at the ambient temperature for 16 hours before bis(3-triethoxysilyl)propyl-tetrasulfide (TEST) (0.42 mL, 0.8 mmol) was added. The resulting light yellow suspension was stirred for 3 hours at room temperature. The reaction mixture was cooled down (ice/water bath), and was diluted with EA (100 mL), washed with saturated NaHC0 ₃ and followed by brine, dried over anhydrous Na ₂ S0 ₄ and concentrated in- vacuo to give a crude product residue. The crude product was purified by flash chromatography on silica gel and then further purified on HPLC to give compound 2a (21.2 mg, 11%) as a white solid. ^X H NMR (CD ₃ OD, 400 MHz) 7.69 (d, J= 8.0 Hz, 1H), 6.06 (d, J= 22.0 Hz, 1H), 5.71 (d, J= 8.0 Hz, 1H), 5.67-5.52 (dd, J= 55.6 Hz, 5.6 Hz, 1H), 5.35-5.26 (dt, J= 25.6 Hz, 4.0 Hz, 1H), 4.66 (m, 2H), 3.85 (d, J = 13.6 Hz, 3H). ³¹ P NMR (CD ₃ OD, 162 MHz) £ 62.66. ESI- LCMS: m/z=402 [M+Na . EXAMPLE 3

Preparation of 4'-azido-2'-(ieoxy-2'-fluorouridine 3',5'-cvclic thiophosphoric acid isopropyl ester (3 a)

[0214] Compound 3a (white solid, 15.5 mg, 7.4%) was prepared using the procedure for preparing compound 2a using 4'-azido-2'-deoxy-2',2'-difluorouridine (150 mg, 0.49 mmol) in place of 4'-azido-2'-deoxy-2'-fluorouridine, and isopropyl Ν,Ν,Ν',Ν'- tetraisopropylphosphordiamidite (213 mg, 0.74 mmol). ^L H NMR (CD ₃ OD, 400 MHz) <57.73 (d, J= 6.8 Hz, 1H), 6.35 (br, 1H), 5.77 (d, J= 8.0 Hz, 1H), 5.35 (br, 1H), 4.92 (m, 1H), 4.78 (m, 2H), 1.40 (t, 6H). ³¹ P NMR (CD ₃ OD, 162 MHz) 58.53. ESI-LCMS: m/z 426 [M+H] ⁺ .

EXAMPLE 4

Preparation of 4'-azido-2'-deoxy-2'-fluorouridine 3',5'-cvclic thiophosphoric acid isopropyl ester (4a)

[0215] To an ice-cold suspension of 4'-azido-2'-deoxy-2'-fluorouridine (100 mg, 0.35 mmol) in dry pyridine (3 mL) was added tetrazole (0.37 M in MeCN, 3 mL, 1.11 mmol), followed by addition of isopropyl NNN'.N'-tetraisopropylphosphordiamidite (151 mg, 0.52 mmol) dropwise after 5 min. The resultant mixture was stirred at the ambient temperature for 16 hours before TEST (0.42 mL, 0.8 mmol) was added. The resulting light yellow suspension was stirred for 3 hours at room temperature. The reaction mixture was cooled down (ice/water bath), diluted with EA (100 mL), washed with saturated aqueous NaHCC and followed by brine, dried over anhydrous Na ₂ SC>4 and concentrated in-vacuo to give a crude product residue. The crude product was purified on silica gel (DCM/MeOH; 95:5) and then further purified on HPLC to give compound 4a (30.5 mg, 21.6%) as a white solid. ² H NMR (CD ₃ OD, 400 MHz) £7.70 (d, J= 8.0 Hz, 1H), 6.15 (d, J= 22A Hz, 1H), 5.71 (d, J= 8.0 Hz, 1H), 5.62 (dd, J = 5.2 Hz, J ₂ = 55.6 Hz, 1H), 5.38-5.47 (m, 1H), 4.80-4.85 (m, 1H), 4.59-4.71 (m, 2H), 1.39-1.41 (m, 6H); ³¹ P NMR (CD ₃ OD, 162 MHz) 59.36; ESI-LCMS: m/z=430 [M+Na] ⁺ .

EXAMPLE 5

Preparation of 4'-azido-2'-deoxy-2'-fluorocvtidine 3',5'-cvclic thiophosphoric acid isopropyl ester (5a)

[0216] Compound 5a (white solid, 7.2 mg, 8.5%) was prepared using the procedure for preparing compound 4a using 4 '-azido-2' -deoxy-2 '-fluorocytidine (60 mg, 0.21 mmol) in place of 4 '-azido-2 '-deoxy-2 '-fluorouridine, and isopropyl Ν,Ν,Ν',Ν'- tetraisopropylphosphordiamidite (92 mg, 0.32 mmol). ^X H NMR (CD ₃ OD, 400 MHz) £7.69 (d, J = 7.6 Hz, 1H), 5.87-5.93 (m, 2H), 5.58-5.67 (m, 1H), 5.50-5.54 (m, 1H), 4.81-4.84 (m, 1H), 4.62-4.69 (m, 2H), 1.41 (t, J= 6.0 Hz, 6H); ³¹ P NMR (CD ₃ OD, 162 MHz) £59.58; ESI-LCMS: m/z 407 [M+H] ⁺ .

EXAMPLE 6

Preparation of 6-(6-Amino-purin-9-yl)-2-isopropoxy-4-methyl-2-oxo-tetrahvdr o-215- furo[3,2-dl [l,3,21dioxaphosphinin-7-ol (6a)

[0217] Step 1 : Compound P6-1 - To a flask containing Pl-1 (20.0 g, 147.3 mmol) was added anhydrous i-PrOH (7.1 g, 1 18 mmol) dropwise over 2 hours at -40°C. The mixture was warmed to room temperature gradually and stirred for another 1 hour. The reaction mixture was distilled under reduced pressure to give pure P6-1 (1 1.5 g, 61%). ^X H NMR (CDC1 ₃ , 400 MHz) 54.98-5.11 (m, 1H), 1.42 (d, J= 3.2 Hz, 6H). ³¹ P NMR (CDCI3, 162 MHz) 5174.48.

[0218] Step 2: Compound P6-2 - To a solution of P6-1 (1 1.5 g, 71.8 mmol) in anhydrous ether (200 mL) was added diisopropylamine (43.5 g, 430.8 mmol) dropwise at 0°C. The mixture was stirred at room temperature overnight. The precipitate was filtered and the filtrate was concentrated to give a residue which was distilled to give P6-2 (8.8 g, 42%) as a colorless oil. ^X H NMR (CDC1 ₃ , 400 MHz) 53.75-3.79 (m, 1H), 3.44-3.58 (m, 4H), 1.14-1.20 (m, 30H).1.42 (d, J= 3.2 Hz, 6H). ¹ P NMR (CDCI3, 162 MHz) δ 1 14.84.

[0219] Step 3 : 2-(l -Hydroxy-ethyl)-5-(6- {[(4-methoxy-phenyl)-diphenyl-methyl ^" |- amino|-purin-9-yl)-tetrahydro-furan-3,4-diol (P6-4) - To a solution of P6-3 (4.5 g, 16 mmol) in dry pyridine (100 mL) was added TMSC1 (12.2 g, 113 mmol) at 0 °C. The mixture was stirred at room temperature overnight, and then MMTrCl (10.0 g, 32.5 mmol) was added. The mixture was stirred at 40-50°C overnight. NH ₄ OH (300 mL) was added, and the mixture was stirred at 30~40°C overnight. The mixture was extracted with ethyl acetate and the organic layer was washed with H2O and brine, dried by anhydrous Na ₂ S04 and filtered. The filtrate was evaporated, and the residue was purified by silica gel column chromatography (DCM: MeOH = 100: 1 to 30: 1) to give P6-4 (5.8 g, 65%) as a brown solid.

[0220] Step 4: 4-(tert-Butyl-dimethyl-silanyloxy)-2-(l-hvdroxy-ethyl)-5-(6- ir(4- methoxy-phenyl)-diphenyl-methyll-amino|-purin-9-yl)-tetrahvd ro-furan-3-ol (P6-5) - To a solution of P6-4 (2.0 g, 3.62 mmol) in dry pyridine (40 mL) was added AgNC (1.23 g, 7.24 mmol) and TBSC1 (0.709 g, 4.71 mmol ) at 0°C. The mixture was stirred at room temperature overnight and then was quenched with water. The solvent was removed under reduced pressure, and the residue was purified by silica gel column chromatography (DCM: MeOH = 300: 1 to 40: 1) to give P6-5 (0.5 g, 20.6%) as a white solid. H NMR (CDCI ₃ , 400 MHz) £8.01 (s, 1H), 7.75 (s, 1H), 7.22-7.34 (m, 12H), 7.03 (s, 1H), 6.79 (d, J = 8.8 Hz, 1H), 6.25 (d, J= 12.0 Hz, 1H), 5.74 (d, J= 7.6 Hz, 1H), 5.29 (s, 1H), 5.05 (dd, J, = 7.2 Hz, J ₂ = 4.8 Hz, 1H), 5.25 (d, J= 4.8 Hz, 1H), 4.18 (s, 1H), 3.89 (dd, J; = 11.6 Hz, J ₂ = 6.4 Hz, 1H), 3.78 (s, 3H), 2.82 (bs, 1H), 1.23 (d, J= 6.4 Hz, 3H), 0.91 (s, 1H), 0.79 (s, 9H), 0.08 (s, 2H), -0.19 (s, 3H), -0.42 (s, 3H).

[0221] Step 5 : (9-[7-ftert-Butyl-dimethyl-silanyloxy)-2-isopropoxy-4-methyl -2- oxo-tetrahvdro-215-furor3,2-diri,3,21dioxaphosphinin-6-yl1-9 H-purin-6-yl}-r(4-methoxy- phenvD-diphenyl-methyll -amine (P6-6) - To a solution of P6-5 (310 mg, 0.464 mmol) in dry pyridine (4 mL) was added a solution of tetrazole in MeCN (0.45 M, 4 mL) and P6-2 (197 mg, 0.679 mmol) at 0°C. After stirring at room temperature overnight, a solution of I ₂ (200 mg, 0.788 mmol) in pyridine (0.6 mL) and H ₂ 0 (0.2 mL) was added at 0°C. The mixture was stirred at room temperature for 30 min. The reaction was quenched with saturated aqueous Na ₂ S ₂ 0 ₃ . The solvent was removed, and the residue was purified via silica gel column chromatography (DCM: MeOH = 500: 1 to 50: 1) to give compound P6-6 (190 mg, 53%).

[0222] Step 6: Compound 6a - P6-6 (90 mg, 0.116 mmol) was dissolved in 70% formic acid (5 mL) and stirred at room temperature overnight. Tetrabutylammonium fluoride (TBAF) (200 mg, 0.766 mmol) was added, and the mixture was stirred at room temperature for another 30 min. The solvent was removed, and the residue was purified by HPLC (0.1% HCOOH in water and MeCN) to afford compound 6a (9.23 mg, 20.1%) as a white solid. ^! H NMR (MeOD, 400 MHz) <58.21 (s, 1H), 8.18 (s, 1H), 6.01 (s, 1H), 5.80-5.84 (m, 1H), 5.00-5.09 (m, 1H), 4.83-4.85 (m, 1H), 4.79-4.71 (m, 1H), 4.50-4.54 (m, 1H), 1.42-1.50 (m, 9H). ³¹ P NMR (MeOD, 162 MHz) £-6.07. LCMS m/z 385.8 (MH ⁺ ). EXAMPLE 7

Preparation of 2-Isopropoxy-6-(6- { [(4-methoxy-phenyl)-diphenyl-methyll -aminol-purin-9- yl)-4-methyl-2-thioxo-tetrahvdro-215-furo[3,2-dl[l,3,21dioxa phosphinin-7-ol (7a)

[0223] Step 1 : (9-[7-(tert-Butyl-dimethyl-silanyloxy)-2-isopropoxy

thioxo-tetrahydro-215-furo[3,2-d1[1 ,21dioxaphosphm^

phenvD-diphenyl-methyll -amine (P7- 1) - To a solution of P6-5 (584 mg, 0.876 mmol) in dry pyridine (7.5 mL) was added a solution of 0.45M tetrazole in MeCN (7.5 mL) and Pl-3 (381 mg, 1.312 mmol) at 0°C. The mixture was stirred at room temperature overnight and then Bis[3- (triethoxysilyl)propyl]tetrasulfide (TEST) (0.707 mL, 1.312 mmol) at 0°C. The mixture was stirred for another hour. The reaction mixture was concentrated and diluted with ethyl acetate, washed with saturated NaHCC and brine, and dried over anhydrous Na ₂ SC>4. The organic layer was concentrated, and the residue was purified via silica gel column chromatography (DCM: MeOH = 500:1 to 50:1) to give compound P7-1 (105 mg, 15%).

[0224] Step 2: Compound 7a - Compound P7-1 (80 mg, 0.102 mmol) was dissolved in 70% formic acid (10 mL) and stirred overnight. The solvent was evaporated, and the residue was dissolved in THF (2 mL). TBAF (162 mg, 0.62 mmol) was added, and the mixture was stirred for 30 min. The solvent was removed, and the residue was purified by preparative HPLC (0.1% HCOOH in water and MeCN) to afford compound 7a (15.81 mg, 36.6%) as a white solid. 'H NMR (MeOD, 400 MHz) 8.25 (s, 1H), 8.22 (s, 1H), 6.00 (s, 1H), 5.54-5.57 (m, 1H), 5.01- 5.06 (m ,1H), 4.69-4.85 (m, 3H), 1.36-1.45 (m, 9H). ³¹ P NMR (MeOD, 162 MHz) δ 62.28, 62.03. LCMS m/z 402.0 (MH ⁺ ). EXAMPLE 8

Preparation of 2-Methoxy-6-(6-{[(4-methoxy-phenyl)-diphenyl-methyll-amino}- purin-9- yl)-4-niethyl-2-oxo-tetrahvdro-215-furo[3,2-dl [1,3,21 dioxaphosphinin-7-ol (8a)

8a

[0225] Step 1 : {9-r7-ftert-Butyl-dimethyl-silan^

tetrahydro-215-mro[3,2-dl[1 ,2]dioxaphosphinin-6-yll-9H-purin-6-yl)-[(4-methoxy-^ diphenyl-methyll-amine (P8-1) - To a solution of P6-5 (500 mg, 0.750 mmol) in dry pyridine (7 mL) was added a solution of 0.45M tetrazole in MeCN (7 mL) and Pl-3 (324 mg, 1.236 mmol) at 0°C. After stirring at room temperature overnight, a solution of (300 mg, 1.182 mmol) in pyridine (0.9 mL) and H ₂ 0 (0.3 mL) was added at 0°C. The mixture was stirred at room temperature for 30 min and quenched with saturated aqueous Na2S2C>3. The solvent was removed, and the residue was purified via silica gel column chromatography (DCM: MeOH = 500: 1 to 50:1) to give P8-1 (216 mg, 38.8%).

[0226] Step 2: Compound 8a - To a solution of P8-1 (216 mg, 0.291 mmol) in DCM

(3.2 mL) was added TsOH H ₂ 0 (307 mg, 1.615 mmol). The mixture was warmed to room temperature and stirred overnight. The reaction was quenched with saturated aqueous Na ₂ CC>3. The organic layer was evaporated, and the residue was purified by preparative HPLC (0.1% HCOOH in water and MeCN) to afford compound 8a (10.33 mg, 9.6%) as a white solid. ^! H NMR (MeOD, 400 MHz) <58.24 (s, 1H), 8.23 (s, 1H), 6.04 (s, 1H), 5.66-5.73 (m, 1H), 5.04-5.12 (m, 1H), 4.81-4.84 (m, 1H), 4.52-4.67 (m, 1H), 3.88 (2d, J= 11.6 Hz, 3H), 1.43-1.47 (m, 3H). ³¹ P NMR (MeOD, 162 MHz) δ 3.59-3.91. LCMS m/z 357.9 (MH ⁺ ). EXAMPLE 9

Preparation of 2-Methoxy-6-(6-{[(4-methoxy-phenyl)-diphenyl-methyll-amino}- purin-9- yl)-4-methyl-2-thioxo-tetrahvdro-215-furo[3,2-dl[l,3,21dioxa phosphinin-7-ol (9a)

[0227] Step 1 : {9-r7-(tert-Butyl-dimethyl-silanyloxy)-2-methox

thioxo-tetrahvdro-215-furo[3,2-d1[1 ,21dioxaphosphm^

phenvD-diphenyl-methyll -amine (P9- 1) - To a solution of P6-5 (190 mg, 0.285 mmol) in dry pyridine (2.5 mL) was added a solution of 0.45M tetrazole in MeCN (2.5 mL) and Pl-3 (118 mg, 0.450 mmol) at 0°C. After stirring at room temperature overnight, Bis[3- (triethoxysilyl)propyl]tetrasulfide (TEST) was added (0.194 mL, 0.36 mmol) at 0°C. The mixture was stirred for 1 hour, and the reaction mixture was concentrated, diluted with ethyl acetate, washed with saturated NaHCC>3 and brine, and dried over anhydrous Na ₂ SC>4. The organic layer was concentrated, and the residue was purified via a silica gel column chromatography (DCM: MeOH=500: l to 50: 1) to give P9-1 (375 mg, crude).

[0228] Step 2: Compound 9a - Compound P9-1 (375 mg, crude) was dissolved in 70% formic acid (10 mL) and stirred overnight. The solvent was evaporated, and the residue was dissolved in THF (10 mL). TBAF (191 mg, 0.73 mmol) was added, and the mixture was stirred for 30 min. The solvent was removed, and the residue was purified by preparative HPLC (0.1% HCOOH in water and MeCN) to afford compound 9a (10.2 mg, 5.5% total yield over steps 1 and 2) as a white solid. 1H NMR (MeOD, 400 MHz) <58.25 (s, 1H), 8.22 (s, 1H), 6.01 (s, 1H), 5.54-5.65 (m, 1H), 5.03-5.08 (m, 1H), 4.51-4.81 (m, 2H), 3.83 (2d, J= 14.0 Hz, 3H), 1.40-1.48 (m, 3H). ³¹ P NMR (MeOD, 162 MHz) 65.09. LCMS m/z 374.0 (MH ⁺ ). EXAMPLE 10

Preparation of l-f7-Hvdroxy-2-methoxy-7-methyl-2-thioxo-tetrahvdro-215-furo [3,2- dl [l,3,21dioxaphosphinin-6-yl)-lH-pyrimidine-2,4-dione (10a)

P10-1 10a

[0229] To a solution of PlO-1 (320 mg, 1.24 mmol) in dry pyridine (9.0 mL) was added a solution of 0.45 M tetrazole in MeCN (9 mL) and Pl-2 (390 mg, 1.49 mmol) at 0°C. The reaction mixture was stirred at room temperature overnight, and bis[3- (triethoxysilyl)propyl]tetrasulfide (803 mg, 1.49 mmol) was then added at 0°C. The mixture was stirred for another hour. The reaction mixture was concentrated and diluted with ethyl acetate, washed with saturated NaHC ⁽ ¾ and brine, and dried over anhydrous Na ₂ SC>4. The organic layer was concentrated, and the residue was purified by HPLC (MeCN and 0.1% HCOOH in water) to give compound 10a as a white solid (35 mg, 7.7%). ^l H NMR (MeOD, 400 MHz) δ 7.63-7.65 (d J = 8.0 Hz, 1H), 6.07 (s, 1H), 5.75-5.79 (m, 1H), 4.60-4.70 (m, 1H), 4.21- 4.46 (m, 1H), 4.10-4.12 (m, 1H), 3.81-3.90 (m, 3H), 1.26 (m, 3H). ³¹ P NMR (MeOD, 162 MHz) 64.3, 67.1. ESI-LCMS m/z 350.9 [M + H] ⁺ .

EXAMPLE 11

Preparation of l-(7-Hvdroxy-2-isopropoxy-7-methyl-2-thioxo-tetrahydro-215-f uro [3,2- dl [l,3,21dioxaphosphinin-6-yl)-lH-pyrimidine-2,4-dione (11a)

[0230] To a solution of PlO-l (155 mg, 0.60 mmol) in dry pyridine (4.0 mL) was added a solution of 0.45 M tetrazole in MeCN (3.33 mL) and P6-1 (190 mg, 0.72 mmol) at 0°C. The reaction mixture was stirred at room temperature overnight, and bis[3- (triethoxysilyl)propyl]tetrasulfide (388 mg, 0.72 mmol) was then added at 0°C. The mixture was stirred for another hour. The reaction mixture was concentrated and diluted with ethyl acetate, washed with saturated NaHC(¾ and brine, and dried over anhydrous a ₂ S04. The organic layer was concentrated, and the residue was purified by HPLC (MeCN and 0.1% HCOOH in water) to give compound 11a as a white solid (21 mg, 9.1%). ^l H NMR (MeOD, 400 MHz) 7.61-7.66 (m, 1H), 6.08 (s, 1H), 5.78-5.80 (m, 1H), 4.82-4.97 (m, 1H), 4.61-4.66 (m, 1H), 4.29-4.43 (m ,1H), 4.09-4.23 (m, 1H), 1.37-1.42 (m, 6H), 1.25 (s, 3H). ³¹ P NMR (MeOD, 162 MHz) £65.2, 61.3. ESI-LCMS m/z 379.0 [M + H] ⁺ .

EXAMPLE 12

Preparation of 2 ^' -C,0 ⁶ -Dimethylguanosine 3 ^' ,5 ^' -cyclic O-pivaloyloxymethyl

phosphorothioate ( 12a)

[0231] Step 1 : Iodomethyl pivalate - Chloromethyl pivalate (1.0 mL, 6.90 mmol) was added to a mixture of Nal (2.08 g, 13.80 mmol) and dry MeCN (10 mL). The reaction mixture was stirred at room temperature overnight in the dark. The mixture was evaporated to dryness. The resulting residue was dissolved in dichloromethane and washed with 5% aqueous NaHSC>3 and brine. The organic layer was dried over Na ₂ SC> ₄ and evaporated to dryness. The resulting iodomethyl pivalate was used without further purification in the next step.

[0232] Step 2: Compound 12a - N ² -(4-Methoxytrityl)-2 ^' -C,0 ⁶ -dimethylguanosine 3 ^' ,5 ^' -cyclic phosphorothioate was dissolved in dry MeCN (3 mL) and iodomethyl pivalate (56 mg g, 0.23 mmol) was added. The reaction mixture was stirred for 2.5 hours at room temperature. Saturated aqueous NaHCCb was added, and the crude product was extracted with dichloromethane. The organic layer was dried over Na ₂ S0 ₄ and evaporated to dryness. The residue was dissolved in 80% aqueous acetic acid (2.0 mL), and the reaction mixture was stirred at room temperature for 20 hours. The reaction mixture was evaporated to dryness, and the resulting residue was coevaporated twice with water. The crude product was purified by silica gel chromatography eluting with dichlroromethane containing 10% MeOH. Compound 12a was obtained as white solid in 14% yield (15.0 mg). *H NMR (500 MHz, CD ₃ OD) δ: 7.95 (s, 1H, H8); 5.93 (s, 1H, HI ^' ), 5.58-5.54 (m, 2H, SCH ₂ ), 4.80-4.69 (m, 3H, H3 ^' , H4 ^' , H5 ^" ); 4.45 (m, 1H, H5 ^' ); 4.06 (s, 3H, OMe); 1.20 (s, 3H, C(Me) ₃ ); 1.10 (s, 1H, 2 ^' -Me). ¹ C NMR (126 MHz, CD ₃ OD) δ: 177.48 (C=0), 161.50 (C6), 160.22 (C2), 152.66 (C4), 139.14 (C8), 129.34 (C5), 95.15 (CI ^' ), 81.87 (C3 ^' ), 76.76 and 76.70 (C2 ^' ), 71.00, 70.93, 70.80 and 70.81 (C4 ^' and C5 ^' ), 60.23 and 60.20 (SCH ₂ ), 52.87 (OMe), 38.52 (spiro C of Piv), 25.85 (C(Me) ₃ ), 18.18 (2 ^' -Me). ³¹ P NMR (202 MHz, CD ₃ OD) δ: 23.13. HR-ESI-MS: [M+H] ⁺ observed 504.1323, calculated 504.1312.

EXAMPLE 13

HCV Replicon Assay

Cells

[0233] Huh-7 cells containing the self-replicating, subgenomic HCV replicon with a stable luciferase (LUC) reporter were cultured in Dulbecco's modified Eagle's medium (DMEM) containing 2mM L-glutamine and supplemented with 10% heat-inactivated fetal bovine serum (FBS), 1% penicillin-streptomyocin, 1% nonessential amino acids, and 0.5 mg/mL G418.

Determination of anti-HCV activity

[0234] Determination of 50% inhibitory concentration (EC5 ₀ ) of compounds in HCV replicon cells were performed by the following procedure. On the first day, 5,000 HCV replicon cells were plated per well in a 96-well plate. On the following day, test compounds were solubilized in 100% DMSO to lOOx the desired final testing concentration. Each compound was then serially diluted (1 :3) up to 9 different concentrations. Compounds in 100% DMSO are reduced to 10% DMSO by diluting 1 : 10 in cell culture media. The compounds were diluted to 10% DMSO with cell culture media, which were used to dose the HCV replicon cells in 96-well format. The final DMSO concentration was 1%. The HCV replicon cells were incubated at 37°C for 72 hours. At 72 hours, cells were processed when the cells are still subconfluent. Compounds that reduce the LUC signal are determined by Bright-Glo Luciferase Assay (Promega, Madison, WI). % Inhibition was determined for each compound concentration in relation to the control cells (untreated HCV replicon) to calculate the EC50.

[0235] Compounds of Formula (I) are active in the replicon assay. The antiviral activity of exemplary compounds is shown in Table 5, where 'A' indicates an EC50 < 1 μΜ, 'B' indicates an EC ₅₀ > 1 μΜ and < 10 μΜ, and 'C indicates an EC ₅₀ > 10 μΜ and < 100 μΜ. Table 5

EXAMPLE 14

Combination of Compounds

Combination Testing

[0236] Two or more test compounds are tested in combination with each other using an HCV genotype lb HCV replicon harbored in Huh7 cells with a stable luciferase (LUC) reporter. Cells are cultured under standard conditions in Dulbecco's modified Eagle's medium (DMEM; Mediatech Inc, Herndon, VA) containing 10% heat-inactivated fetal bovine serum (FBS; Mediatech Inc, Herndon, VA) 2mM L-glutamine, and nonessential amino acids (JRH Biosciences). HCV re licon cells are plated in a 96-well plate at a density of 10 ⁴ cells per well in DMEM with 10% FBS. On the following day, the culture medium is replaced with DMEM containing either no compound as a control, the test compounds serially diluted in the presence of 2% FBS and 0.5% DMSO, or a combination of one or more test compounds serially diluted in the presence of 2% FBS and 0.5% DMSO. The cells are incubated with no compound as a control, with the test compounds, or the combination of compounds for 72 h. The direct effects of the combination of the test compounds are examined using a luciferase (LUC) based reporter as determined by the Bright-Glo Luciferase Assay (Promega, Madison, WI). Dose-response curves are determined for individual compounds and fixed ratio combinations of two or more test compounds.

[0237] The effects of test compound combinations are evaluated by two separate methods. In the Loewe additivity model, the experimental replicon data is analyzed by using CalcuSyn (Biosoft, Ferguson, MO), a computer program based on the method of Chou and Talalay. The program uses the experimental data to calculate a combination index (CI) value for each experimental combination tested. A CI value of <1 indicates a synergistic effect, a CI value of 1 indicates an additive effect, and a CI value of >1 indicates an antagonistic effect.

[0238] The second method that is utilized for evaluating combination effects uses a program called MacSynergy II. MacSynergy II software was kindly provided by Dr. M. Prichard (University of Michigan). The Prichard Model allows for a three-dimensional examination of drug interactions and a calculation of the synergy volume (units: μΜ ² %) generated from running the replicon assay using a checkerboard combination of two or more inhibitors. The volumes of synergy (positive volumes) or antagonism (negative volumes) represent the relative quantity of synergism or antagonism per change in the concentrations of the two drugs. Synergy and antagonism volumes are defined based on the Bliss independence model. In this model, synergy volumes of less than -25 indicate antagonistic interactions, volumes in the -25 - 25 range indicate additive behavior, volumes in the 25 - 100 range indicate synergistic behavior and volumes >100 indicate strong synergistic behavior. Determination of in vitro additive, synergistic and strongly synergistic behavior for combinations of compounds can be of utility in predicting therapeutic benefits for administering the combinations of compounds in vivo to infected patients.

[0239] Furthermore, although the foregoing has been described in some detail by way of illustrations and examples for purposes of clarity and understanding, it will be understood by those of skill in the art that numerous and various modifications can be made without departing from the spirit of the present disclosure. Therefore, it should be clearly understood that the forms disclosed herein are illustrative only and are not intended to limit the scope of the present disclosure, but rather to also cover all modification and alternatives coming with the true scope and spirit of the invention.