Synthesis of 5α-Cholestan-6-one Derivatives with Some Substituents at the C-1, C-2, or C-3 Position(Organic,Chemical)
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In order to investigate the regioselectivity of Baeyer-Villiger oxidation, thirty 5α-cholestan-6-one derivatives with various substituents (methyl, hydrogen, acetoxymethyl, methoxy, acetyloxy, benzoyloxy, trifluoroacetyloxy, p-toluenesulfonyloxy) at the C-1, C-2, or C-3 position were synthesized from cholesterol. The 6-oxo functional group of 5α-cholestan-6-one derivatives was introduced via hydroboration. The 3β-derivatives were readily obtained by using the native 3β-hydroxyl group of cholesterol. The 3α-isomers were obtained by inversion of the configuration of the 3β-tosylate 24 with tetra-n-butylammonium acetate in refluxing 2-butanone. The 2β-isomers were derived from the 2-ene 43 by bromohydrination, LiAlH_4 reduction, and esterification. The 2β-to 2α-hydroxyl group inversion was achieved by Birch reduction of the 2-oxo steroid 51. The 1α-derivatives were derived from the known 6β-acetoxy-la-hydroxy-5α-cholest-2-ene (57).
- Chem. Pharm. Bull.
Chem. Pharm. Bull. 35, 986-995, 1987
The Pharmaceutical Society of Japan