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

We 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. Regioselective Intramolecular Synthesis of Furo[3,2-c]chromen and Imidazo[1,2-a]pyridine derivatives.image