Quantitative and Stereospecific Dihydroxylations of Δ5-Steroids: A Green Synthesis of Plant Growth Hormone Intermediates

Dihydroxylated Delta(5)-steroids are key intermediates in preparing steroids bearing a 5 alpha-hydroxy-6-oxo moiety, which are plant growth hormones. Quantitative and stereospecific dihydroxylations of Delta(5)-steroids have been realized, using H2O2 catalyzed by KI and H2SO4 at 80 degrees C in aqueous dioxane. The workup consisted only of concentrating the solvents and filtering the products; no chromatography was needed. The reaction conditions tolerate various functional groups on the Delta(5)-steroids. A mechanism for this reaction is proposed and the reason that the reaction is quantitative and stereospecific is explained.