- Bile acids. LXVIII. Allylic and benzylic photo-chemical oxidation of steroids
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To provide 7-oxocholesterol derivatives in yields superior to those obtained by chemical oxidation, the preparation of steroidal allylic or benzylic ketones was studied. Air-induced oxidation was investigated with a highly selective low energy UV lamp in the presence of mercuric bromide. With this procedure cholesteryl acetate, 5-cholestene-3β,27-diol diacetate, 24(R)-24-methyl-5-cholesten-3β-yl acetate, 24(R)-24-methyl-5-cholesten-3β-yl acetate, 24(R)-24-ethyl-5-cholesten-3β-yl acetate and 24(R)-24-ethyl-(22E)-cholestra-5,22-dien-3β-yl acetae were oxidized to the allylic keto-derivative in good yeilds; estradiol-17β diacetate was similarly converted to the 6-oxo-product in improved yield. This method can be very useful in the synthesis of 7-oxocholesteryl acetate and its analogs and 6-oxo-estratrienes.
- Tal,Elliott
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- 5β,6β-Epoxidation of 3β-Cholesteryl Acetate and its Analogues
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The treatment of acetylated Δ5-steroids with chromyl diacetate at low temperature afforded the 5β,6β-epoxy derivatives with stereoselectivity greater than 90 per cent. - keywords: Cholesterol, Sitosterol, Campesterol, Stigmasterol, Pregnenolone, Stereoselective Epoxidation
- Galagovsky, L. R.,Burton, G.,Gros, E. G.
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p. 806 - 810
(2007/10/02)
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