Steroids of unnatural configuration. Part X. A quantitative study of the epoxidation of lumisterol and its esters

Abstract

Oxidation of lumisterol with perbenzoic and peroxylauric acids, and of lumisteryl acetate and lumisteryl 3,5-di-nitrobenzoate with peroxylauric acid gives 5β,6β-epoxides in high yields. The second-order rate constants (l. mole^–1 sec.^–1) are respectively 12·6, 3·35, 2·58 × 10^–2, and 1·76 × 10^–2: bonding in the transition state is thought to accelerate the reactions of lumisterol. Ring-opening of the 3β-hydroxy-5β,6β-epoxide with benzoic acid to the 3β,5β-dihydroxy-6β-benzoate is much slower (k 5·72 × 10^–5).