Regioselective O-Alkylation of Sterically Hindered Steroidal Ethynyl Carbinols

Autor:	G. R. Duncan, Z. G. Hajos
Rok vydání:	1975
Předmět:	Steric effects Chemistry Yield (chemistry) Organic Chemistry Regioselectivity Organic chemistry General Chemistry Alkylation Ring (chemistry) Catalysis
Zdroj:	Canadian Journal of Chemistry. 53:2971-2974
ISSN:	1480-3291 0008-4042
DOI:	10.1139/v75-418
Popis:	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 1b and 2b 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 1c from 5β-pregnan-3β-ol-20-one 3a via 3b, 3c and 3d.
Databáze:	OpenAIRE
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