Collect. Czech. Chem. Commun. 1983, 48, 2423-2435

Preparation and absolute configuration at C(22) of 21,26,27-trinor-5α-cholestane-22,25-diol derivatives

Vladimír Pouzar, Soňa Vašíčková, Pavel Drašar, Ivan Černý and Miroslav Havel

Institute of Organic Chemistry and Biochemistry, Czechoslovak Academy of Sciences, 166 10 Prague 6


Reaction of 5α-pregnan-21-al (V), obtained from ester of the corresponding acid III via the alcohol IV, with lithium salt of 1-methoxymethoxy-2-propyne afforded both the isomeric 25-methoxymethoxy-21,26,27-trinor-5α-cholest-23-yn-22-ols (VI and VIII) which were converted into two 21,26,27-trinor-5α-cholestane-22,25-diols (XI, XV). Absolute configuration of the alcohols X and XIV was assigned by chemical correlation with derivatives XXVI and XXVII of known absolute configuration at C(20). The correlation was based on reduction of thiocarbonates derived from the diols XXII and XXIV for which also Cotton effects of their complexes with nickel acetylacetonate were studied. Both diols were prepared from 5α-pregnan-20-one (XVIII) via 5α-pregn-20-yne (XIX) and the 21,26,27-trinor-5α-cholest-20-ene derivative XXI.