Nucleoside derivatives as inhibitors of viral polymerases

1. A compound of structural formula (I):

or a pharmaceutically acceptable salt thereof; wherein

ring A is a 5- or 6-membered ring, optionally containing 1, 2 or 3 heteroatoms selected from N, O and S, and optionally containing one, two or three double bonds, and also optionally substituted by 1, 2 or 3 groups independently selected from CN, C 1-6 alkyl, C 2-6 alkenyl, C 2-6 alkynyl, C 1-6 alkoxy, halogen, C 1-6 haloalkyl, C 1-6 haloalkoxy, NR x R y , NR z C(O)NR x R y , NR x C(O)OR y , OC(O)NR x R y , C(O)R x , C(O)OR x , C(O)NR x R y , SR x , S(O)R x , SO 2 R x , SO 2 NR x R y , wherein R x , R y and R z are independently selected from hydrogen and C 1-6 alkyl; and further optionally fused to another 5- or 6-membered ring, which ring optionally contains 1, 2 or 3 heteroatoms selected from N, O and S, and which ring optionally contains 1, 2 or 3 double bonds, and which ring is optionally substituted by 1, 2 or 3 groups independently selected from C 1-6 alkyl, C 1-6 alkoxy and halogen;

Q 1 is hydrogen or amino;

W is CH or amino;

X is CH, C or N;

the dotted bond represents a single bond when X is CH or N, or the dotted bond represents a double bond when X is C;

Y is C═O or CH 2 ;

R 1 is hydrogen, methyl, hydroxymethyl, fluoromethyl or N 3 ;

R 2 and R 3 are independently hydrogen, fluorine, hydroxy, C 1-4 alkyl or C 1-4 alkoxy;

R 4 is hydrogen, PO 3 H 2 , P 2 O 6 H 3 , P 3 O 9 H 4 or a group R 6 wherein R 6 is C 1-16 alkylcarbonyl, C 2-18 alkenylcarbonyl, C 1-10 alkyloxycarbonyl, C 3-6 cycloalkylcarbonyl, C 3-6 cycloalkyloxycarbonyl or a monophosphate prodrug residue of the formula

wherein R 7 is hydrogen, C 1-6 alkyl optionally substituted with one substituent selected from the group consisting of fluoro, hydroxy, methoxy, amino, carboxy, carbamoyl, guanidino, mercapto, methylthio, 1H-imidazolyl, and 1H-indol-3-yl; or R 7 is phenyl, benzyl or phenethyl each optionally substituted with one to two substituents independently selected from the group consisting of halogen, hydroxy, and methoxy;

R 8 is hydrogen or methyl;

or R 7 and R 8 together with the carbon atom to which they attached form a 3- to 6-membered aliphatic spirocyclic ring system;

R 9 is aryl, arylalkyl, heteroaryl or

wherein R 11 is C 1-16 alkyl, C 2-20 alkenyl, (CH 2 ) 0-4 C 7-9 cycloalkyl, (CH 2 ) 0-4 C 3-9 cycloalkenyl or adamantly each optionally substituted with one to three substituents independently selected from halogen, hydroxy, carboxy, C 1-4 alkoxy, trifluoromethyl and (CH 2 ) 0-4 NR 15 R 16 wherein R 15 and R 16 are independently selected from hydrogen and C 1-6 alkyl; or R 15 and R 16 , together with the nitrogen atom to which they are attached form a 4- to 7-membered heterocyclic ring optionally containing 1 or 2 more heteroatoms selected from N, O and S, which ring is optionally substituted by C 1-6 alkyl;

R 10 is hydroxy or a group OR 16 wherein R 16 is CH 2 OC(O)R 17 or CH 2 CH 2 SR 17 where R 17 is C 1-6 alkylcarbonyl optionally substituted by a hydroxyl group or R 16 is (CH 2 ) 2-4 —O—(CH 2 ) 1-17 CH 3 , or an aromatic ring selected from phenyl, naphthyl, pyridinyl, pyrimidinyl, pyrazinyl, pyridazinyl, indolyl, quinolinyl, or isoquinolinyl, wherein the aromatic ring is optionally substituted with one to five substituents independently selected from the group consisting of halogen, C 1-4 alkyl, C 1-4 alkoxy, C 1-4 alkylthio, cyano, nitro, amino, carboxy, trifluoromethyl, trifluoromethoxy, C 1-4 alkylamino, di(C 1-4 alkyl)amino, C 1-4 alkylcarbonyl, C 1-4 alkylcarbonyloxy, and C 1-4 alkyloxycarbonyl; or R 10 and R 5 form a bond to make a cyclic phosphate group;

R 12 is C 6-16 alkyl, C 2-20 alkenyl, (CH 2 ) 0-2 C 7-9 cycloalkyl, (CH 2 ) 0-2 C 3-9 cycloalkenyl, OC 1-6 alkyl or adamantyl; and

R 13 and R 14 are independently selected from hydrogen and C 1-6 alkyl;

or R 13 and R 14 together with the carbon atom to which they attached form a 3- to 6-membered aliphatic spirocyclic ring system;

R 5 is hydrogen or methyl, C 1-16 alkylcarbonyl, C 2-18 alkenylcarbonyl, C 1-10 alkyloxycarbonyl, C 3-6 cycloalkylcarbonyl, C 3-6 cycloalkyloxycarbonyl or an amino acyl residue of structural formula:

wherein R 18 is hydrogen, C 1-5 alkyl or phenylC 0-2 alkyl; and R 19 is hydrogen, C 1-4 alkyl, C 1-4 alkylsulfonyl or phenylC 0-2 alkylsulfonyl, or a group COR 20 wherein R 20 is C 1-4 alkyl optionally substituted by phenyl, C 1-4 alkoxy optionally substituted by phenyl, or C 1-4 alkylamino optionally substituted by C 1-4 alkyl optionally substituted by phenyl.

2. A compound of structural formula (Ia):

or a pharmaceutically acceptable salt thereof; wherein:

ring A is a 5- or 6-membered ring, optionally containing 1, 2 or 3 heteroatoms selected from N, O and S, and optionally containing one, two or three double bonds, and also optionally substituted by 1, 2 or 3 groups independently selected from CN, C 1-6 alkyl, C 2-6 alkenyl, C 2-6 alkynyl, C 1-6 alkoxy, halogen, C 1-6 haloalkyl, C 1-6 haloalkoxy, NR x R y , NR z C(O)NR x R y , NR x C(O)OR y , OC(O)NR x R y , C(O)R x , C(O)OR x , C(O)NR x R y , SR x , S(O)R x , SO 2 R x , SO 2 NR x R y , wherein R x , R y and R z are independently selected from hydrogen and C 1-6 alkyl; and further optionally fused to another 5- or 6-membered ring, which ring optionally contains 1, 2 or 3 heteroatoms selected from N, O and S, and which ring optionally contains 1, 2 or 3 double bonds, and which ring is optionally substituted by 1, 2 or 3 groups independently selected from C 1-6 alkyl, C 1-6 alkoxy and halogen;

X is CH, C or N;

the dotted bond represents a single bond when X is CH or N, or the dotted bond represents a double bond when X is C;

Y is C═O or CH 2 ;

R 1 is hydrogen, methyl, hydroxymethyl, fluoromethyl or N 3 ;

R 2 and R 3 are independently hydrogen, fluorine, hydroxy, C 1-4 alkyl or C 1-4 alkoxy;

R 4a is hydrogen, C(O)C 1-10 alkyl, PO 3 H 2 , P 2 O 6 H 3 , P 3 O 9 H 4 or P(O)R a R b ; wherein

R a and R b are each independently hydroxy, OAr, OCH 2 CH 2 SC(═O)C 1-4 alkyl, OCH 2 CH 2 SC(═O)C 1-4 hydroxyalkyl, OCH 2 O(C═O)OC 1-4 alkyl, NHCR c R d CO 2 R e , NR c R d ,OCH(C 1-4 alkyl)O(C═O)C 1-4 alkyl,

Ar is phenyl, naphythyl, pyridinyl, pyrimidinyl, pyrazinyl, pyridazinyl, indolyl, quinolinyl or isoquinolinyl, wherein Ar is optionally substituted with one to five substituents independently selected from the group consisting of halogen, C 1-4 alkyl, C 1-4 alkoxy, C 1-4 alkylthio, cyano, nitro, amino, carboxy, trifluoromethyl, trifluoromethoxy, C 1-4 alkylamino, di(C 1-4 alkyl)amino, C 1-4 alkylacarbonyl, C 1-4 alkylcarbonyloxy and C 1-4 alkyloxycarbonyl;

R c is hydrogen, C 1-6 alkyl, phenyl or benzyl, wherein alkyl is optionally substituted with one substituent selected from fluorine, hydroxy, methoxy, amino, carboxy, carbamoyl, guanidino, mercapto, methylthio, 1H-imidazolyl, and 1H-indol-3-yl, and wherein phenyl and benzyl are optionally substituted with one or two substituents independently selected from halogen, hydroxy or methoxy;

R d is hydrogen or methyl;

or R c and R d together with the carbon atom to which they are attached fern form a 3- to 6-membered aliphatic spirocyclic ring system;

R e is hydrogen, C 1-16 alkyl, C 2-20 alkenyl, (CH 2 ) 0-2 C 3-6 cycloalkyl, phenyl, benzyl or adamantyl; wherein alkyl, alkenyl, cycloalkyl and adamantyl are optionally substituted with one to three substituents independently selected from halogen, hydroxy, carboxy, C 1-4 alkoxy; and wherein phenyl and benzyl are optionally substituted with one to three substituents independently selected from halogen, hydroxy, cyano, C 1-4 alkoxy, trifluoromethyl and trifluoromethoxy.

3. A compound according to either claim 1 or claim 2 in which A is a 5- or 6-membered ring, optionally containing one heteroatom selected from N, O and S, and optionally containing two or three double bonds.

4. A compound according to claim 1 in which X is C and the dotted bond represents a double bond or X is N and the dotted bond represents a single bond.

5. A compound according to claim 1 in which R 1 is hydrogen.

6. A compound according to claim 1 in which R 2 is hydroxyl.

7. A compound according to claim 1 in which R 3 is methyl.

8. A compound according to claim 1 in which R 4 or R 4a is hydrogen, C(O)C 1-10 alkyl, PO 3 H 2 , P 2 O 6 H 3 or P 3 O 9 H 4 .

9. A compound according to claim 1 of structural formula (II):

or a pharmaceutically acceptable salt thereof;

wherein R 4b is hydrogen, C(O)C 1-10 alkyl, PO 3 H 2 , P 2 O 6 H 3 , P 3 O 9 H 4 or P(O)R a R b ; where R a and R b are each independently hydroxy, OCH 2 CH 2 SC(═O)C 1-4 alkyl, OCH 2 O(C═O)OC 1-4 alkyl, OPh, NHCHMeCO 2 Et, OCH(C 1-4 alkyl)O(C═O)C 1-4 alkyl,

and ring A is a 5- or 6-membered ring, optionally containing 1 or 2 heteroatoms selected from N, O and S, and containing one, two or three double bonds.

10. A compound according to claim 9 of structural formula (III):

or a pharmaceutically acceptable salt thereof.

11. A compound according to claim 1 , wherein the compound is selected from:

2-(2-C-methyl-beta-D-ribofuranosyl)-2,6-dihydro-7H-2,3,5,6-tetraazadibenzo[C,D,H]azulen-7-one,

2-(2-C-methyl-beta-D-ribofuranosyl)-6,7-dihydro-2H-2,3,5,6-tetraazadibenzo[cd,h]azulene,

2-(2-C-methyl-beta-D-ribofuranosyl)-2,6-dihydro-7H-8-thia-2,3,5,6-tetraazabenzo[CD]cyclopenta[H]azulen-7-one,

2-(2-C-methyl-beta-D-ribofuranosyl)-6,7-dihydro-2H-8-thia-2,3,5,6-tetraazabenzo[CD]cyclopenta[H]azulene,

2-[5-O-(hydroxy{[hydroxy(phosphonooxy)phosphoryl]oxy}phosphoryl)-2-C-methyl-beta-D-ribofuranosyl]-2,6-dihydro-7H-2,3,5,6-tetraazadibenzo[cd,h]azulen-7-one,

2-[5-O-(hydroxy{[hydroxy(phosphonooxy)phosphoryl]oxy}phosphoryl)-2-C-methyl-beta-D-ribofuranosyl]-6,7-dihydro-2H-2,3,5,6-tetraazadibenzo[cd,h]azulene,

2-[5-O-(hydroxy{[hydroxy(phosphonooxy)phosphoryl]oxy}phosphoryl)-2-C-methyl-beta-D-ribofuranosyl]-6,7-dihydro-2H-8-thia-2,3,5,6-tetraazabenzo[c d]cyclopenta[h]azulene,

2-[5-O-(hydroxy{[hydroxy(phosphonooxy)phosphoryl]oxy}phosphoryl)-2-C-methyl-beta-D-ribofuranosyl]-2,6-dihydro-7H-8-thia-2,3,5,6-tetraazabenzo[c d]cyclopenta[h]azulen-7-one,

and pharmaceutically acceptable salts thereof.

12. A method for inhibiting RNA-dependent RNA viral polymerase, a method for inhibiting RNA-dependent RNA viral replication, and/or a method for treating RNA-dependent RNA viral infection in a mammal in need thereof comprising administering to the mammal a therapeutically effective amount of a compound according to claim 1 .

13. A pharmaceutical composition comprising a compound according to claim 1 in association with a pharmaceutically acceptable carrier.

14. A compound according to claim 1 in combination with one or more agents useful for treating HCV infection.