Selective synthesis of some imidazopyridine-fused chromones

A fused heterocyclic scaffold combining the imidazo[1,2-a]pyridine with a substituted chromone was synthesized in a one-pot procedure. The reaction proceeds by intramolecular cyclization of 1-(2-imino-2H-chromen-3-yl)pyridinium chloride in ethanol and in the presence of DABCO. A detailed study of the experimental conditions allowed a clear understanding of the reaction pathway.