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Stereoselective Introduction of Steroid Side Chains at C (17) and C (20)

✍ Scribed by Andrew D. Batcho; Donald E. Berger; Stephen G. Davoust; Peter M. Wovkulich; Milan R. Uskoković

Publisher
John Wiley and Sons
Year
1981
Tongue
German
Weight
340 KB
Volume
64
Category
Article
ISSN
0018-019X

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✦ Synopsis

Abstract

A simple and efficient new method for the highly stereoselective (at C (17) and C (20)) introduction of steroid side chains which are suitably functionalized for further elaboration is presented. The ene reaction of (17 Z)‐ethylidene steroids, which are readily obtained from 17‐keto steroids via a Wittig reaction, with various enophiles such as formaldehyde and acrylate esters leads to useful intermediates which contain the natural steroid configuration at C (20). Catalytic hydrogenation of the Δ^16^‐double bond occurs from the α‐face to stereospecifically generate the correct configuration at C (17). An additional chiral center at C (23) is also introduced stereoselectively by the use of methyl 2‐chloroacrylate as the enophile.

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