Palladium-catalyzed oxidative cyclization of 3-phenoxyacrylates: An approach to construct substituted benzofurans from phenols

摘要

In this paper, a novel and applicable synthesis of benzofurans from commercially available phenols and propiolate through the direct oxidative cyclization has been developed. In the presence of Pd(OAc)_2/PPh _3 and CF_3CO_2Ag, (E)-type 3-phenoxyacrylates underwent reaction smoothly to generate the corresponding benzofurans in good yields in benzene at 110 °C under the air pressure. In addition, this transformation of phenols into benzofurans can also be carried out in one pot. The process was simple and efficient. A tentative mechanism of palladium-catalyzed oxidative cyclization of 3-phenoxyacrylates was proposed.