Solvent-free chemoselective synthesis of some novel substituted 2-arylbenzimidazoles using amino acid-based prolinium nitrate ionic liquid as catalyst

A simple and eco‐friendly protocol for the synthesis of substituted 2‐arylbenzimidazoles is described. In this process, 2‐arylbenzimidazoles were prepared in the presence of a newly introduced ionic liquid prolinium nitrate [Pro]NO3 as catalyst, under solvent‐free condition. This process was performed under mild condition without using any oxidant with good to excellent yields and remarkable chemoselectivity in the absence of any byproduct. The ionic liquid can be recovered easily and reused. J. Heterocyclic Chem., 46, 74 (2009).