Chiral salen Mn(III) immobilized onto sulfoalkyl-modified zinc poly(styrene-phenylvinylphosphonate)-phosphate as effective catalysts for epoxidation of unfunctionalized olefins

Abstract

The heterogeneous catalysts 3a–3c immobilized chiral salen Mn(III) onto sulfoalkyl-modified zinc poly(styrene-phenylvinylphosphonate)phosphate (ZnPSPPP) were prepared and used for the enantioselective epoxidation of unfunctionalized olefins. The catalysts were characterized with FT-IR, UV–vis, XRD, SEM, TEM. All the prepared heterogeneous catalysts exhibited much higher chiral induction than the homogeneous Jacobsen’s catalyst did and could be reused six times without significant loss of activity and enantioselectivity. Surprisedly, the conversions and enantiomeric excess (ee) values increased in the absence of axial base N-methylmorpholine N-oxide (NMO), which were different to what most literatures reported. Meanwhile, the role of axial ligand NMO in the asymmetric epoxidation of unfunctional olefin was also discussed here. Furthermore, this novel type of catalyst can also be validly used in large-scale reactions with superior catalytic disposition being maintained at the same level, which possessed the potentiality for application in industry.