N-Substituted Formamides as C1-Sources for the Synthesis of Benzimidazole and Benzothiazole Derivatives by Using Zinc Catalysts

An efficient and convenient one-pot protocol has been developed for the synthesis of a variety of benzimidazole, benzoxazole, and benzothiazole derivatives. This novel approach uses various o -phenylenediamines and N-substituted formamides (C 1 sources) in a zinc-catalyzed cyclization in the presence of poly(methylhydrosiloxane) to afford the corresponding derivatives as sole products in moderate to excellent yields.