Disclosed are proline derivative compounds of Formula I, salts thereof, and methods for their preparation. Specific examples of compounds of Formula I include: (2S)-2-[[(1,1-dimethylethoxy)carbonyl] amino]-4-(chloroacetyl)aminobutanoyl-(4R)-4-[(7-methoxy-2-phenyl-4-quinolinyl)oxy]-L-prolyl-1-amino-2-ethenyl-N(phenylsulfonyl)-(1R,2S)-cyclopropanecarboxamide, (2S)-2-[[(1,1-dimethylethoxy)carbonyl]amino]-4-(2-propenoyl)methylaminobutanoyl-(4R)-4-[(7-methoxy-2-phenyl-4-quinolinyl)oxy]-L-prolyl-1-amino-2-ethenyl-N(phenylsulfonyl)-(1R,2S)-cyclopropanecarboxamide, and (1aR,3aS,SR,9S,16aS,Z)-11-acryloyl-9-(tert-butoxycarbonylamino)-la-(cyclopropylsulfonylcarbamoyl)-3,8-dioxo-1,1 a,2,3,3a,4,5,6,8,9,10,11,12,13,14,16a-hexadecahydrocyclopropa[n]pyrrolo[2,1-c][1,4,8]triazacyclopentadecin-5-yl-4-fluoroisoindoline-2-carboxylate. Compounds of Formula I are inhibitors of hepatitis C (HCV) protease. The compounds can inhibit the HCV protease, or a mutant thereof, activity irreversibly by covalently modifying a cysteine residue conserved at an equivalent position to Cys159 of HCV protease subtype 1b.
