Patent ID: 7365057

Claim:
A method for the treatment of a Flaviviridae virus infection in a host infected with a Flaviviridae virus comprising administering to the host an effective treatment amount of a compound of formula or a pharmaceutically acceptable salt thereof wherein: R 1 is hydrogen, mono, di or triphosphate; acyl; an amino acid ester; a carbohydrate; a peptide; or a pharmaceutically acceptable leaving group which when administered in vivo provides a compound wherein R 1 is independently H or phosphate; Base is selected from the group consisting of: wherein W 1 is N, CH, CCN, CX 3 , CBr, CCl, or CF; X is O; each X 3 is independently straight chained, branched or cyclic optionally substituted alkyl, CH 3 , NH 2 or fluoro; R 8 , R 10 and R 11 are H; R 9 is OH or OR 2 R 12 is C(Y 3 ) 3 ; R 13 is OR 2 or fluoro; each Y 3 is independently H or F; each R 2 is independently hydrogen, acyl, an amino acid ester, a carbohydrate, a peptide, or a pharmaceutically acceptable leaving group which when administered in vivo provides a compound wherein R 2 is H; and each R 4 and R 5 is independently hydrogen, acyl, alkyl, lower alkyl, alkenyl, alkynyl or cycloalkyl.