Asymmetric epoxidation of unfunctionalized olefins catalyzed by chiral salen-Mn (III) immobilized on alkoxyl-modified ZnPS-PVPA

摘要

Novel layered heterogeneous chiral salen Mn (III) catalysts anchored onto ZnPS-PVPA by means of click chemistry are synthesized and employed in asymmetric epoxidations of unfunctionalized olefins. The catalysts manifest superior catalytic performances (conv%, up to >99; ee%, up to >99) according to the epoxidations of alpha-methylstyrene, styrene, indene and 1-octene. But for 6-cyano- 2,2-dimethylchromene and 6-nitro-2,2-dimethylchromene, configuration of epoxides are reversed. Moreover, the catalysts could still indicate comparable properties (yield, 82%; ee, 86%) after recycling for nine times and excellent functions in large-scale reactions, which paves the way for the application in industry.