The present invention provides
ribonucleoside 2′,3′-cyclic acetals of
structural formula I which are precursors or prodrugs of inhibitors of
RNA-dependent
RNA viral
polymerase. These compounds are precursors of inhibitors of
RNA-dependent RNA
viral replication and are useful for the treatment of RNA-dependent RNA
viral infection. They are particularly useful as precursors or prodrugs of inhibitors of
hepatitis C
virus (HCV) NS5B
polymerase, as precursors or prodrugs of inhibitors of HCV replication, and / or for the treatment of
hepatitis C infection. The invention also describes pharmaceutical compositions containing such
ribonucleoside 2′,3′-cyclic acetals alone or in combination with other agents active against RNA-dependent RNA
viral infection, in particular HCV infection. Also disclosed are methods of inhibiting RNA-dependent
RNA polymerase, inhibiting RNA-dependent RNA
viral replication, and / or treating RNA-dependent RNA
viral infection with the
ribonucleoside 2′,3′-cyclic acetals of the present invention.