On reaction of sterol hydroperoxides with superoxide

Reduction of sterol hydroperoxides 3 beta-hydroxy-5 alpha-cholest-6-ene-5-hydroperoxide and cholesterol 7 alpha-hydroperoxide by KO2 (or other strong base in air) solubilized by crown ether in dimethylsulfoxide gave only corresponding alcohols, but in the presence of cholesterol (or other sterols) gave 3 beta-hydroxycholest-5-en-7-one together with the corresponding alcohols. Both hydroperoxides likewise gave the corresponding alcohol and ketone products with KO2 in benzene and in oxidations by ceric ammonium nitrate in a biphasic system. The 7-ketone product is recognized as deriving from termination reactions of sterol peroxyl and/or oxyl radicals.