Nucleosides With Non-Natural Bases as Anti-Viral Agents

1 . A method for treating a pestivirus, flavivirus or hepacivirus infection in a host comprising administering to said host an effective amount of a nucleoside compound of Formula (i)

or a pharmaceutically acceptable salt or prodrug thereof, wherein:

W is O;

Q 1 is C—R where R is H or halogen;

Q 3 is C—R where R is H or halogen, preferably F;

Q 4 and Q 6 each independently is N, C—H, or N—H;

Q 5 is C—R where R is NR 4 R 5 , NHR 4 , or NH 2

Q 9 and Q 10 each independently is C;

Z is Formula (IV),

wherein X is O, S or N—H;

R 1 , R 2 , and R 3 each independently is H, optionally substituted phosphate or phosphonate, acyl, alkyl, or amino acid;

R 8 and R 11 each independently is H, hydroxyl, alkyl, alkenyl, alkynyl, chloro, bromo, fluoro, iodo, or O(alkyl); and

R 6 and R 10 each independently is H, alkyl or halo substituted alkyl, Cl, F, Br, or I;

R 12 is H; and

Each R 4 and R 5 independently is H, acyl, or alkyl.

2 . The method of claim 1 wherein:

Q 1 is C—R where R is H;

Q 3 is C—R where R is halogen;

Q 4 and Q 6 each independently is N;

Z is Formula (IV), wherein X is O; R 1 , R 2 , R 3 , R 8 , R 10 and R 11 each independently is H; and R 6 is lower alkyl.

3 . A method for the treatment of a host infected with a flavivirus, pestivirus or hepacivirus infection comprising administering to said host an effective treatment amount of a compound of Formula (xviii)

or a pharmaceutically acceptable salt or prodrug thereof, wherein:

Q 1 , Q 4 and Q 6 each independently is C—R or N;

Q 3 and Q 5 each independently is C—R or N;

Q 9 and Q 10 each independently is C;

Z is Formula (III),

wherein X is O, S or N—R where R is H;

R 1 is H, optionally substituted phosphate or phosphonate, acyl, alkyl, or amino acid;

R 6 and R 10 is H, alkyl or halo substituted alkyl, chloro, bromo, fluoro, or iodo;

R 8 and R 11 each independently is H, OH, alkyl, alkenyl, alkynyl, chloro, bromo, fluoro, iodo, or O(alkyl);

R 12 is H; and

R is each independently H, halo, alkyl, alkenyl, alkynyl, alkoxy, alkoxyalkyl, hydroxyalkyl, cycloalkyl, nitro, cyano, OH, ether, NH 2 , amide, SH, thioalkyl, CF 3 , CH 2 OH, CH 2 F, CH 2 Cl, CH 2 CF 3 , C(═O)OH, C(═O)Oalkyl or aryl, C(═O)-alkyl, C(═O)-aryl, C(═O)-alkoxyalkyl, C(═O)NH 2 , C(═O)NHalkyl, C(═O)N(alkyl) 2 , or N 3 .

4 . The method of claim 3 , wherein:

Q 1 , Q 4 and Q 6 each independently is C—R;

Q 3 and Q 5 each independently is N;

X is O;

R 1 is H;

R 8 and R 11 each independently is H or lower alkyl;

R 6 is lower alkyl; and

R 10 is H or alkyl.

5 . A method for the treatment of a host infected with a flavivirus, pestivirus or hepacivirus infection comprising administering to the host an effective treatment amount of a compound of Formula (B)

or a pharmaceutically acceptable salt or ester thereof, optionally in a pharmaceutically acceptable carrier.

6 . A method for the treatment of a host infected with a flavivirus, pestivirus or hepacivirus infection comprising administering to the host an effective treatment amount of a compound of Formula (C)

or a pharmaceutically acceptable salt or ester thereof, optionally in a pharmaceutically acceptable carrier.

7 . A method for the treatment of a host infected with a flavivirus, pestivirus or hepacivirus infection comprising administering to the host an effective treatment amount of a compound of Formula (E)

or a pharmaceutically acceptable salt or ester thereof, optionally in a pharmaceutically acceptable carrier.

8 . A method for the treatment of a host infected with a flavivirus, pestivirus or hepacivirus infection comprising administering to the host an effective treatment amount of a compound of Formula (M)

or a pharmaceutically acceptable salt or ester thereof, optionally in a pharmaceutically acceptable carrier.

9 . A method for the treatment of a host infected with a flavivirus, pestivirus or hepacivirus infection comprising administering to the host an effective treatment amount of a compound of Formula (N)

or a pharmaceutically acceptable salt or ester thereof, optionally in a pharmaceutically acceptable carrier.

10 . A method for the treatment of a host infected with a flavivirus, pestivirus or hepacivirus infection comprising administering to the host an effective treatment amount of a compound of Formula (O)

or a pharmaceutically acceptable salt or ester thereof, optionally in a pharmaceutically acceptable carrier.

11 . A method for the treatment of a host infected with a flavivirus, pestivirus or hepacivirus infection comprising administering to the host an effective treatment amount of a compound of Formula (Q)

or a pharmaceutically acceptable salt or ester thereof, optionally in a pharmaceutically acceptable carrier.

12 . A compound of Formula (B)

or a pharmaceutically acceptable salt or ester thereof.

13 . A compound of Formula (C)

or a pharmaceutically acceptable salt or ester thereof.

14 . A compound of Formula (E)

or a pharmaceutically acceptable salt or ester thereof.

15 . A compound of Formula (M)

or a pharmaceutically acceptable salt or ester thereof.

16 . A compound of Formula (N)

or a pharmaceutically acceptable salt or ester thereof.

17 . A compound of Formula (O)

or a pharmaceutically acceptable salt or ester thereof.

18 . A compound of Formula (Q)

or a pharmaceutically acceptable salt or ester thereof.

19 . A pharmaceutical composition comprising a compound of any one of claims 12 - 18 , or a pharmaceutically acceptable salt or ester thereof, and a pharmaceutically acceptable carrier.

20 . Use of a compound of any one of claims 12 - 18 or a pharmaceutically acceptable salt or ester thereof, optionally in a pharmaceutically acceptable carrier, in a method for the treatment of a host infected with a flavivirus, pestivirus or hepacivirus infection.

21 . Use of a compound of any one of claims 12 - 18 or a pharmaceutically acceptable salt or ester thereof, optionally in a pharmaceutically acceptable carrier, in the manufacture of a medicament for the treatment of a host infected with a flavivirus, pestivirus or hepacivirus infection.