Bile acids. LXVIII. Allylic and benzylic photo-chemical oxidation of steroids.
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 cholesterol acetate, 5-cholestene-3 beta, 27-diol diacetate, 24(R)-24-methyl-5-cholesten-2 beta-yl acetate, 24(R)-24-ethyl-5-cholesten-28-yl acetate and 24(R)-24-ethyl-(22E)-cholesta-5,22-dien-3 beta-yl acetate were oxidized to the allylic keto-derivative in good yields; estradiol-17 beta 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.
D000498:Allyl Compounds; D001593:Benzyl Compounds; D001647:Bile Acids and Salts / Q000138:chemical synthesis*; D007202:Indicators and Reagents; D007700:Kinetics; D010084:Oxidation-Reduction; D010777:Photochemistry; D013256:Steroids; D014466:Ultraviolet Rays
D000498:Allyl Compounds; D001593:Benzyl Compounds; D001647:Bile Acids and Salts; D007202:Indicators and Reagents; D013256:Steroids