Copper(II)-Mediated Aerobic Synthesis of Imidazo­[1,2‑<i>a</i>]pyridines via Cascade Amino­methylation/Cyclo­isomerization of Alkynes

A single copper­(II)-catalyzed three-component cascade amino­methyla­tion/cyclo­isomeriza­tion of propiolates to form imidazo­[1,2-<i>a</i>]­pyridines was explored. A straightforward method was developed for the practical synthesis of functionalized imidazo­[1,2-<i>a</i>]­pyridines from benzaldehydes, 2-amino­pyridines, and propiolate derivatives catalyzed by Cu­(OAc)₂ hydrate in the presence of air. The protocol is marked by excellent yields, functional group tolerance, and, above all, adaptability to synthesize imidazo­[1,2-<i>a</i>]­pyridine-based drug molecules such as Alpidem