Iron-catalyzed [3 + 2 + 1] annulation of 2-aminobenzimidazoles/3-aminopyrazoles and aromatic alkynes using N,N-dimethylaminoethanol as a one carbon synthon for the synthesis of pyrimido[1,2-a]benzimidazoles and pyrimido[1,2-b]indazoles

A simple and efficient method for the synthesis of pyrimido[1,2- a ]benzimidazoles and pyrimido[1,2- b ]indazoles by a three-component [3 + 2 + 1] annulation catalyzed by FeCl 3 has been established.