Constraining asymmetric organometallic catalysts within mesoporous supports ZnPS–BrPPAS boosts their enantioselectivity

Abstract

Novel layered heterogeneous chiral salen Mn(III) catalysts are synthesized with organic–inorganic hybrid material ZnPS–BrPPAS as the support and employed in the asymmetric epoxidations of unfunctionalized olefins. Characterizations indicate that the different linkers could contribute to the morphology varying from schistose structure to spheric particle. The catalysts manifest superior catalytic dispositions (yield, up to >99%; ee, up to >99%) in the epoxidations of olefins such as α-methylstyrene and indene. Moreover, the catalysts could be recovered and reused up to nine times with retention of catalytic dispositions. In addition, the reversal configurations of epoxides are observed with respect to 6-cyano-2,2-dimethylchromene and 6-nitro-2,2-dimethylchromene.