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

Vediyappan Ramesh; Sivakumar Shanmugam; Natarajan Savitha Devi

Index: 10.1002/slct.201800270

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Abstract

A 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.