Recent synthetic methodologies for imidazo[1,5-<i>a</i>]pyridines and related heterocycles

Imidazo[1,5-<i>a</i>]pyridine is a significant structural component of a large number of agrochemicals and pharmaceuticals. The synthesis of imidazo[1,5-<i>a</i>]pyridine has been a subject of intense research for numerous decades. A large number of transformations are now available to conveniently access imidazo[1,5-<i>a</i>]pyridine from readily available starting materials. This review details the recent development in imidazo[1,5-<i>a</i>]pyridine construction involving cyclocondensation, cycloaddition, oxidative cyclization, and transannulation reactions.