Compounds of formula I: wherein: R 2 is hydrogen or C 1 -C 4 alkyl； R 3 and R 4 are hydrogen, -C(=O)R 5 , or -C(=O)CHR 6 -NH 2 ； or R 3 is hydrogen and R 4 is a monophosphate-, diphosphate-, or triphosphate ester； or R 3 is hydrogen, -C(=O)CHR 5 , or -C(=O)CHR 6 -NH 2 and R 4 is each R 5 is hydrogen, C 1 -C 6 alkyl, or C 3 -C 7 cycloalkyl； R 6 is hydrogen or C 1 -C 6 alkyl； R 7 is optionally substituted phenyl； naphthyl； or indolyl； R 8 and R 8' are hydrogen, C 1 -C 6 alkyl, benzyl； or R 8 and R 8' combined form C 3 -C 7 cycloalkyl； R 9 is C 1 -C 6 alkyl, benzyl, or optionally substituted phenyl； provided that R 2 , R 3 and R 4 are not all hydrogen； or a pharmaceutically acceptable salt or solvate thereof； pharmaceutical formulations with the compounds I； the use of compounds I, including the compounds of formula I wherein R 2 , R 3 and R 4 are all hydrogen, as HCV inhibitors.
