Regioselectivity of the reaction of 3-keto steroids with potassium superoxide

Abstract

The regioselectivity in the oxidation of different types of 3-keto steroids with potassium superoxide in the presence of 18-crown-6 has been investigated. In all cases, the reaction products are directly related to the enolization process of the substrates. The oxidation of a 2-enolate results in oxidative cleavage of ring A with loss of carbon monoxide to give the lactols (2) and (10) and the aldehyde (8). However, the oxidation of 4-enolates occurs with oxidative cleavage of ring A to give the ketones (7) and (12), the latter with loss of carbon monoxide.