Expanded perlite: an inexpensive natural efficient heterogeneous catalyst for the green and highly accelerated solvent-free synthesis of 5-substituted-1H-tetrazoles using [bmim]N3 and nitriles

A versatile, green and highly accelerated protocol for preparing 5-substituted-1H-tetrazoles is reported. In this method, 5-substituted-1H-tetrazoles are synthesized from nitriles and [bmim]N-3, in the presence of the expanded perlite as an inexpensive natural efficient heterogeneous catalyst, under solvent-free condition. A wide variety of aryl nitriles underwent [3 + 2] cycloaddition to afford the desired tetrazoles in good to excellent yields, rapidly. This method has the advantages of high yields, short reaction times, simple methodology, and easy work-up. The catalyst can be recovered by simple filtration and reused delivering good yields.