Regioselective O-Alkylation of Sterically Hindered Steroidal Ethynyl Carbinols

A synthetic method is described for the direct regioselective O-alkylation of sterically hindered acetylenic carbinols in the presence of other alcoholic functional groups. The method is not sensitive to the configuration of the latter or to the stereochemistry of ring fusion; the preparation of 5β-...

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Bibliographic Details
Published in:Canadian journal of chemistry 1975-10, Vol.53 (19), p.2971-2974
Main Authors: Hajos, Z. G, Duncan, G. R
Format: Article
Language:English
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Summary:A synthetic method is described for the direct regioselective O-alkylation of sterically hindered acetylenic carbinols in the presence of other alcoholic functional groups. The method is not sensitive to the configuration of the latter or to the stereochemistry of ring fusion; the preparation of 5β- and 5α- 20α-ethynyl-20β-methoxy-pregnan-3β-ol 1 b and 2 b from the corresponding 20-ols is exemplary. In addition, a straightforward high yield four-step procedure is described for the preparation of the regio-isomer, 20α-ethynyl-3β-methoxy-5β-pregnan-20β-ol 1 c from 5β-pregnan-3β-ol-20-one 3 a via 3 b, 3 c and 3 d.
ISSN:0008-4042
1480-3291
DOI:10.1139/v75-418