the present invention relates to peptidomimetic compounds which inhibit serine protease activity , particularly the activity of hepatitis c virus ns3 - ns4a protease . as such , they act by interfering with the life cycle of the hepatitis c virus and are also useful as antiviral agents . the compounds of this invention have a bridged bicyclic moiety at the p2 position . the invention further relates to compositions comprising these compounds either for ex vivo use or for administration to a patient suffering from hcv infection . the invention also relates to methods of treating an hcv infection in a patient by administering a composition comprising a compound of this invention .