Er(OTf)3‐Catalyzed Multicomponent Synthesis of 3,4‐Dihydro‐2H‐pyran via Hetero‐Diels‐Alder Reaction under Ambient Temperature

Abstract

AbstractA one‐pot synthesis of 3,4‐dihydro‐2H‐pyran derivatives has been achieved using substituted styrenes, aqueous formaldehyde and various β‐keto esters. This multicomponent protocol employs erbium (III) triflate as a catalyst affording 3,4‐dihydro‐2H‐pyran derivatives in good to excellent yields (72‐98%). Furthermore, synthesis of the bicyclic fused ring system such as 2‐aryl‐2,3,4,6,7,8‐hexahydro‐5H‐pyrano[2, 3‐d]pyridazin‐5‐one 6 was achieved from the corresponding 3,4‐dihydro‐2H‐pyran 4.