Issue 2, 2016

Asymmetric epoxidation of unfunctionalized olefins accelerated by thermoresponsive self-assemblies in aqueous systems

Abstract

A novel thermoresponsive surfactant-type chiral salen MnIII catalyst was developed by axially grafting “smart” poly(N-isopropylacrylamide) (PNIPAAm) onto the metal center of a neat chiral salen MnIII complex. Characterization data suggests thermoresponsive micellization behavior of the obtained catalyst in water. The chiral metallomicellar catalyst acted as a nanoreactor to carry out asymmetric epoxidation of unfunctionalized olefins in water and dramatically accelerated reaction rates. Outstanding catalytic efficiency was observed in the nanoreactor system. In particular, quantitative conversion (99%) of styrene with high enantioselectivity (39%) was achieved over 0.8 mol% of the catalyst within 3 min, giving an unprecedented TOF value (2.48 × 103 h−1) which is significantly higher than that obtained over previously reported homogeneous or heterogeneous systems. Moreover, the catalyst could be easily recovered by thermocontrolled separation and reused with high activity for five cycles.

Graphical abstract: Asymmetric epoxidation of unfunctionalized olefins accelerated by thermoresponsive self-assemblies in aqueous systems

Article information

Article type
Paper
Submitted
25 Jun 2015
Accepted
06 Aug 2015
First published
18 Aug 2015

Catal. Sci. Technol., 2016,6, 488-496

Author version available

Asymmetric epoxidation of unfunctionalized olefins accelerated by thermoresponsive self-assemblies in aqueous systems

Y. Zhang, R. Tan, G. Zhao, X. Luo and D. Yin, Catal. Sci. Technol., 2016, 6, 488 DOI: 10.1039/C5CY00953G

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