Highly Enantioselective Epoxidation of Unfunctionalized Olefins Catalyzed by Chiral Jacobsen's Catalyst Immobilized on Phenoxy-Modified Zirconium Poly(syrene-phenylvinylphosphonate)phosphate

Chiral Jacobsen's catalyst was axially Immobilized onto phenoxy-modified zirconium poly(styrene-phenylvinylphosphonate)phosphate (ZPS-PVPA). The immobilized catalysts show comparable ee values for asymmetric epoxidation of styrene and much higher ee values for alpha-methylstyrene (73.7% vs. 54.0%) and indene (99.9% vs. 65.0%) than the homogeneous Jacobsen's catalyst. Moreover, the assynthesized catalysts are relatively stable and can be recycled at least five times without significant loss of activity and enantioselectivity. A point worth emphasizing is that the heterogeneous catalysts afforded remarkable increases of conversion and ee values in the absence of expensive O-coordinating axial bases for the asymmetric epoxidation of olefins, especially for the epoxidation of alpha-methylstyrene (conversion: from 24.3% to 99.9%, ee: from 29.4% to 73.7%), which may overcome the last obstacle for the potential industry application of chiral Jacobsen's catalyst.