A simple, highly regioselective and efficient reaction of indole with epoxides under solvent-free conditions

Abstract

Lithium perchlorate has been found to be an inexpensive and efficient catalyst for the ring opening of epoxides by indole and N-methylindole, which provides an environmentally friendly method for the synthesis of substituted indoles. A complete regioselectivity in favor of nucleophilic attack at the benzylic carbon atom of aromatic epoxides, such as styrene oxide, is observed. However, aliphatic unsymmetrical alkene oxides undergo selective nucleophilic attack at the sterically less-hindered carbon atom. This catalyst offers several advantages, such as short reaction time, high yields, lower catalytic loading, simple experimental procedure, and easy isolation of the products, under solvent-free conditions.