Peroxide oxidation of Δ4-3-ketosteroids

Treatment of Δ4-3-ketosteroids with tert-buly hydroperoxide in the presence of lithium hydroxide leads to the formation of the corresponding 4β,5β epoxides stereospecifically and in good yield. The stereospecificity of this reaction is explicable in terms of the accepted mechanism for the hydrogen peroxide epoxidation of Δ4-3-ketosteroids.The use of aqueous sodium peroxide as oxidant leads to the production of the corresponding Δ4-3,6-diones. A mechanism for this reaction is proposed in which the key step is autoxidation of the corresponding deconjugated Δ5-3-ketone, produced from the starting material insitu by the action of the reagents. Lithium peroxide does not oxidize androst-4-ene-3,17-dione at C-6, but produces the 4,5 epoxides in low yield together with an A-nor-3,5-secoacid.