Silver-catalyzed intramolecular hydroamination of alkynes in aqueous media: Efficient and regioselective synthesis for fused benzimidazoles

A simple, convenient and green synthetic approach to diverse fused tricyclic benzimidazoles has been developed by Ag(I) complex catalyzed intramolecular hydroamination under the classic method or by microwave irradiation in water. This strategy presents an operationally simple and environmentally friendly transformation, in which various substituted benzimidazoles facilitated efficient cyclization.