Preparation of 1,2-substituted benzimidazoles via a copper-catalyzed three component coupling reaction.

1,2-Substituted benzimidazoles were prepared by simply stirring a mixture of copper catalysts, N -substituted o -phenylenediamines, sulfonyl azides and terminal alkynes. Particularly, the intermediate N -sulfonylketenimine occurred with two nucleophilic addition and the sulfonyl group was eliminated via cyclization. In a way, sulfonyl azides and copper catalysts activated the terminal alkynes to synthesize benzimidazoles.