Improved chromium-catalyzed allylic oxidation of Δ5-steroids with t-butyl hydroperoxide

Various chromiumVI-catalyzed conditions have been tested to improve the oxidation of Δ5-steroids with t-BuOOH to their corresponding 5-en-7-ones. The use of PDC or the association of CrO3 with an amine as the catalyst and CH2Cl2 or PhCF3 as the solvent led usually to the best yields. A minor reaction pathway was the epoxidation of the double bond.

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