One‐pot sequential regioselective intramolecular synthesis of furo[3,2‐c]chromen and imidazo[1,2‐a]pyridine via catalyst‐free and basic conditions

Abstract

AbstractWe developed a sequential intramolecular ring‐closure‐opening‐closure pathway using a catalyst‐free and organo‐base catalyzed system for the synthesis of fused regioselective tricyclic furo[3,2‐c]chromen and bicyclic imidazo[1,2‐a]pyridine via a one‐pot three‐component reaction. The protocol involved a Knoevenagel and Michael adduct via intramolecular cyclization with 4‐hydroxycoumarin, aromatic glyoxal, and 2‐aminopyridine under heating and ambient conditions with very good yields. The merits of this methodology were studied, and new practical ways were developed to access furo[3,2‐c]chromen and imidazo[1,2‐a]pyridine moieties.