A versatile and straightforward approach to the 21-oxidation of β-substituted and α,β-unsaturated 20-oxosteroids

Abstract 21-Hydroxylation and acetoxylation of 20-oxosteroids, either α,β-unsaturated or β-substituted, were successfully achieved through oxidation of the corresponding silyl enol ethers with m -CPBA followed by smooth hydrolytic cleavage of the 21-alkylsilyloxy derivatives. These conditions, which have not been previously used to synthesize such compounds, allow a high degree of regio and chemoselectivity and are specially useful for the chemical synthesis of 16α,21-dihydroxy-20-oxosteroids.