The First Kilogram Synthesis of Beclabuvir, an HCV NS5B Polymerase Inhibitor

The process development and kilogram-scale synthesis of beclabuvir (BMS-791325, 1) is described. The convergent synthesis features the use of asymmetric catalysis to generate a chiral cyclopropane fragment and coupling with an indole fragment via an alkylation. Subsequent palladium-catalyzed intramolecular direct arylation efficiently builds the central seven-membered ring. The target was prepared in 12 linear steps with five isolations in an overall yield of 8%.