Design of New Chiral Phase-Transfer Catalysts with Dual Functions for Highly Enantioselective Epoxidation of α,β-Unsaturated Ketones

Takashi Ooi, Daisuke Ohara, Masazumi Tamura, and Keiji Maruoka*
Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo, Kyoto 606-8502, Japan
J. Am. Chem. Soc., 2004, 126 (22), pp 6844–6845
DOI: 10.1021/ja048600b
Publication Date (Web): May 18, 2004
Copyright © 2004 American Chemical Society
*

In papers with more than one author, the asterisk indicates the name of the author to whom inquiries about the paper should be addressed.

, maruoka@kuchem.kyoto-u.ac.jp

Abstract

Abstract Image

A new chiral ammonium bromide, 1-Br, possessing diarylmethanol functionality as a substrate recognition site has been designed as a promising, dual-functioning catalyst for the highly enantioselective epoxidation of α,β-unsaturated ketones under mild phase-transfer conditions. For instance, vigorous stirring of a mixture of chalcone, 1-Br (3 mol %), and 13% NaOCl in toluene at 0 °C for 24 h gave rise to epoxy chalcone quantitatively with 96% ee. A variety of α,β-unsaturated ketones can also be epoxidized with rigorous stereochemical control, clearly demonstrating the effectiveness and utility of the present system. Further, a successful single-crystal X-ray diffraction analysis of 1-PF6 uncovered its distinctive three-dimensional molecular architecture and provided useful information for postulating the transition state.

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History

  • Published In Issue June 09, 2004
  • Received March 11, 2004

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