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A highly beta-stereoselective catalytic epoxidation of Delta(5)-unsaturated steroids with a novel ruthenium(II) complex under aerobic conditions

Kesavan, Venkitasamy and Chandrasekaran, Srinivasan (1998) A highly beta-stereoselective catalytic epoxidation of Delta(5)-unsaturated steroids with a novel ruthenium(II) complex under aerobic conditions. In: The Journal of Organic Chemistry, 63 (20). pp. 6999-7001.

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Official URL: http://pubs.acs.org/doi/abs/10.1021/jo980829k

Abstract

Catalytic beta-stereoselective epoxidation of Delta(5)-unsaturated steroid derivatives has been effected by a novel ruthenium(II) bioxazoline complex under aerobic conditions. The reactions are regio- and stereoselective. The reaction conditions provide the corresponding 5 beta,6 beta-epoxides with high degree of stereoselectivity (88-96%) in very good yields, while oxidation of steroid derivatives with peracids leads to 5 alpha,6 alpha-epoxides as the major products. The overall conformation of the steroid nucleus is nearly planar in the cholesteryl ester, while it is bent at the junction between the rings A and B in the 5 beta,6 beta-epoxide. This change from pseudo trans- to cis-stereochemistry of the A-B ring junction provides more room for the catalyst to approach from the beta-face of the steroidal skeleton.

Item Type: Journal Article
Additional Information: Copyright of this article belongs to American Chemical Society.
Department/Centre: Division of Chemical Sciences > Organic Chemistry
Date Deposited: 12 Aug 2009 08:02
Last Modified: 19 Sep 2010 04:59
URI: http://eprints.iisc.ernet.in/id/eprint/17903

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