Regioselective synthesis of 9,10-dihydro-6H-chromeno[4,3-d]imidazo-[1,2-a]pyridin-6-one derivatives

Abstract

A method for regioselective synthesis of 9,10-dihydro-6H-chromeno[4,3-d]imidazo[1,2-a]pyridin-6-one derivatives has been developed. The reaction was readily performed by reacting inexpensive materials, 4-chloro-3-formylcoumarin and HKAs, in EtOH catalyzed by Et₃N. This protocol has many advantages including convenient operation, short reaction times, green solvent, and simple purification by washing the crude products with 95% EtOH, defined as GAP (Group-Assistant-Purification) chemistry. The library of 9,10-dihydro-6H-chromeno[4,3-d]imidazo[1,2-a]pyridin-6-one derivatives has been constructed with excellent yields.