A Direct, Regioselective Palladium-Catalyzed Synthesis of N-Substituted Benzimidazoles and Imidazopyridines

Unsymmetric, N-substituted benzimidazoles and imidazopyridines can be prepared directly from 2-halonitroarenes and amides through Pd(TFA)(2)/(R)-BINAP-catalyzed cross-coupling and subsequent reductive aminocyclization. This sequence can be conducted by a one-pot procedure. The method is versatile and allows the straightforward, regioselective preparation of these important nitrogen heterocycles.