Discovery of novel potent and selective dipeptide hepatitis C virus NS3/4A serine protease inhibitors

Starting from the previously reported HCV NS3/4A protease inhibitor BILN 2061 (1), we have used a fast-follower approach to identify a novel series of HCV NS3/4A protease inhibitors in which (i) the P3 amino moiety and its capping group have been truncated, (ii) a sulfonamide is introduced in the P1 cyclopropyl amino acid, (iii) the position 8 of the quinoline is substituted with a methyl or halo group, and (iv) the ring size of the macrocycle has been reduced to 14 atoms. SAR analysis performed with a limited set of compounds led to the identification of N-{17-[8-chloro-2-(4-isopropylthiazol-2-yl)-7-methoxyquinolin-4-yloxy]-2,14-dioxo-3,15-diazatricyclo [13.3.0.0 [Bartenschlager, R.; Lohmann, V. J. Gen. Virol. 2000, 81, 1631; Vincent Soriano, Antonio Madejon, Eugenia Vispo, Pablo Labarga, Javier Garcia-Samaniego, Luz Martin-Carbonero, Julie Sheldon, Marcelle Bottecchia, Paula Tuma, Pablo Barreiro Expert Opin. Emerg. Drugs, 2008, 13, 1–19]]octadec-7-ene-4-carbonyl}(1-methylcyclopropyl)(1-methylcyclopropyl)sulfonamide 19l an extremely potent (Ki = 0.20 nM, EC50 = 3.7 nM), selective, and orally bioavailable dipeptide NS3/4A protease inhibitor, which has features attractive for further preclinical development.