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

✍ Scribed by Xiaochuan Zou; Xiangkai Fu; Yuedong Li; Xiaobo Tu; Shaodong Fu; Yunfei Luo; Xiaoju Wu

• Publisher: John Wiley and Sons
• Year: 2010
• Tongue: English
• Weight: 318 KB
• Volume: 352
• Category: Article
• ISSN: 1615-4150
• DOI: 10.1002/adsc.200900424

✦ Synopsis

Abstract

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 α‐methylstyrene (73.7% vs. 54.0%) and indene (99.9% vs. 65.0%) than the homogeneous Jacobsen’s catalyst. Moreover, the as‐synthesized 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 α‐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.