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

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