On the reaction of cholesteryl acetate with tert-butyl hydroperoxide in the presence of tris(acetylacetonato)iron(III).

A model reaction was investigated for the biological oxyfunctionalization of steroid. The benzene solution of cholesteryl acetate (I), tert-butyl hydroperoxide, and tris (acetylacetonato) iron (III) in a molar ratio of 1.2 : 9.2 : 0.13 was refluxed under argon atmosphere and time-course of the reaction was followed for 24 hours. The products identified were 3β-acetoxycholest-5-en-7-one (II), 3β-acetoxycholest-5-en-7-ols (III ; trace), 3β-acetoxy-5, 6-epoxycholestanes (IV), and the alkyl peroxides (Va, Vb, and Vc). These peroxides showed maximum concentration in the early period of the reaction and most of the substrate (I) was consumed by this time. The structures of Va and Vb were elucidated to be 3β-acetoxycholest-5-ene-7α-tert-butylperoxide and its 7β-epimer, respectively. The product Vc was assumed to be 3β-acetoxycholest-6-ene-5ξ-tert-butylperoxide. The ketone (II) was a major product when the peroxides (Va and Vb) came into contact with the oxidation system mentioned above ; the yields from Va and Vb were 56 and 94%, respectively. Thus it was concluded that the major final product (II) may be formed through the intermediary peroxides (V) in the titled reaction.