An improved synthesis of 13-epi-androstanes and of 13-epi-oestranes

Abstract

Treatment of a 17-hydroxyimino-steroid with refluxing acetic anhydride and pyridine affords an equilibrium mixture of 13-epi-enimide and 13-epi-enamide. A free-radical mechanism is proposed. Acidic hydrolysis gives the 17-oxo-13-epi-steroid in high overall yield.