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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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
Publication:	The Journal of Organic Chemistry
Publisher:	American Chemical Society
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.ac.in/id/eprint/17903

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