Collect. Czech. Chem. Commun. 1981, 46, 2758-2765

Synthesis and absolute configuration at C(20) of 21,26,27-trinor-5α-cholestan-25→20-olide derivatives

Vladimír Pouzar and Miroslav Havel

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


Reaction of the aldehyde I with 4-(methoxymethoxy)butylmagnesium chloride yielded compounds II and VII which were converted into diols III and VIII, respectively. By oxidation of the diols III and VIII were obtained saturated lactones XVI and XX, respectively, which were converted into unsaturated lactones XIX and XXIII, respectively. On the basis of chemical correlation with methyl ethers XIV and XV of a known configuration at C(20), the compounds II-VI, XII, XVI-XIX were assigned the 20R-configuration whereas 20S configuration was established for the compounds VII-XI, XIII and XX-XXIII.