A Protocol to 2-Aminobenzimidazoles via Copper-Catalyzed Cascade Addition and Cyclization of <i>o</i>-Haloanilines and Carbodiimides

An efficient strategy for the synthesis of a variety of 2-animobenzimidazole derivatives has been developed. The reaction proceeded from o-haloanilines and carbodiimides via copper(I)-catalyzed domino reaction in the presence of tert-butoxide to afford the corresponding 2-animobenzimidazole derivatives in good to excellent yields. o-Haloanilines could be o-iodoaniline, o-bromoaniline, and o-chloroaniline derivatives. Carbodiimides could be symmetrical and unsymmetrical substrates with aryl or alkyl substituents. The reaction exhibited a good regioselectivity when unsymmetrical carbodiimides were employed.