Metal-free synthesis of imidazo[1,5-a]pyridines via elemental sulfur mediated sequential dual oxidative Csp3-H amination.

A simple and efficient approach has been developed for the synthesis of imidazo[1,5-a]pyridines using the elemental sulfur mediated sequential dual oxidative Csp3-H amination of 2-pyridyl acetates and amines under metal- and peroxide-free conditions. Broad substrate scope, operational simplicity and gram-scale ability make this chemistry very practical.