Compounds of the formula I: including any possible stereoisomers thereof, wherein: R4 is a monophosphate, diphosphate or triphosphate ester; or R4 is R7 is optionally substituted phenyl, optionally substituted naphthyl, or optionally substituted indolyl; R8 and R8′ are hydrogen, C1-C6alkyl, benzyl, or phenyl; or R8 and R8′ form C3-C7cycloalkyl; R9 is C1-C10alkyl, C3-C7cycloalkyl, phenyl or phenyl-C1-C6alkyl, wherein the phenyl moiety in phenyl or phenyl-C1-C6alkyl is optionally substituted; or a pharmaceutically acceptable salt or solvate thereof; pharmaceutical formulations and the use of compounds I as HCV inhibitors.