Pinto RMA, Salvador JAR, Le Roux C, Carvalho RA, Silva MR, Beja AM, Paixão JA. Bismuth(III) salt-catalyzed Westphalen and "backbone" rearrangements of 5 beta,6 beta-epoxysteroids synthesis and structural elucidation of new olefinic 19-nor and 18,19-dinorsteroids.
Steroids 2008;
73:549-61. [PMID:
18295811 DOI:
10.1016/j.steroids.2008.01.006]
[Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/08/2007] [Revised: 12/21/2007] [Accepted: 01/09/2008] [Indexed: 11/28/2022]
Abstract
A new process using the "ecofriendly" bismuth(III) salts as catalysts for the Westphalen and "backbone" rearrangements of 5 beta,6 beta-epoxysteroids is reported. This method is particularly sensitive to changes on solvent, temperature, stereochemistry of starting epoxysteroid, and its substituent at C17. Depending on the reaction conditions, either Westphalen-type or "backbone" rearranged products were obtained, all being 3 beta-acetoxy-6 beta-hydroxy-substituted. Several new olefinic 19-nor and 18,19-dinorsteroids were obtained and their structural elucidation was fully accomplished using 2D NMR and X-ray crystallography techniques.
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