Copper-Catalyzed Construction of Benzo[4,5]imidazo[2,1-]isoquinolines Using Calcium Carbide as a Solid Alkyne Source.

A method for the synthesis of benzo[4,5]imidazo[2,1-]isoquinolines through Sonogashira cross-coupling/nucleophilic addition tandem reactions using calcium carbide as a solid alkyne source, 2-(2-bromophenyl)benzimidazoles as starting materials, and copper as a catalyst is described. The target products can also be synthesized through one-pot three-component reactions of -phenylenediamines, -bromobenzaldehydes, and calcium carbide. Both reaction routes can also be scaled up to gram scale.