Copper-catalyzed domino addition/double cyclization: an approach to polycyclic benzimidazole derivatives.

An efficient and versatile method for the assembly of novel polycyclic benzimidazole derivatives has been developed by Cu-catalyzed domino addition/double cyclization reactions. A wide variety of polycyclic benzimidazole derivatives, which might be used as synthetic medicines and functional materials, were successfully assembled from bis-(o-haloaryl)carbodiimides. Unexpected N-methylated benzo[4,5]imidazo[1,2-a]indoles can also be selectively assembled. Multibonds and polycyclic moieties were conveniently formed in one pot during these domino processes.