Rapid, metal-free and aqueous synthesis of imidazo[1,2-]pyridine under ambient conditions

A novel, rapid and efficient route to imidazo[1,2- a ]pyridines under ambient, aqueous and metal-free conditions is reported. The NaOH-promoted cycloisomerisations of N -propargylpyridiniums give quantitative yield in a few minutes (10 g scale). A comparison of common green metrics to current routes showed clear improvements, with at least a one order of magnitude increase in space-time-yield. A route to access the privileged imidazo[1,2- a ]pyridine scaffold in one step, 110 minutes using only aqueous NaOH, is reported.