ChemInform Abstract: Synthesis and Oxidation of Pregna‐3,5‐dien‐20‐ols and ‐20‐one and Selective Reduction of Pregna‐3,5‐dien‐20‐one.

Abstract

280ChemInform Abstract NaBH4 reduction of progesterone (I) affords the (20S)-and (20R)-alcohols (II) and (III). Oxidation of this mixture with an equimolar amount of Jones reagent yields the pregna-3,5-dien-20-one (IV) as the sole isolable product, whereas a large excess of the oxidizing reagent produces a mixture of the derivatives (IV)-(VII). The selective reduction of the ketone (IV) using various reducing agents is also investigated. In general, these reactions afford mixtures of the epimeric alcohols (II) and (III), the latter being the major component. L-Selectride yields (II) and (III) in an approximately 1:1 ratio.