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Please login to access the full content or check if you have access via Variation 8: By Treatment with Oxygen and Triethyl Phosphite

DOI: 10.1055/sos-SD-026-00761

Suffert, J.Science of Synthesis, (200526940.

Steroidal ketones having a tertiary α-hydrogen atom react at 25°C with oxygen in the presence of a strong base and triethyl phosphite to afford the corresponding α-ketols. The method is especially useful for the introduction of a 17α-hydroxy group into 20-oxo steroids, as in the conversion of the ketone 225 into 3β-acetoxy-17β-hydroxy-16β-methyl-5α-pregnan-20-one (226) (Scheme 102).[‌192‌] A combination of dimethylformamide and tert-butyl alcohol is the solvent of choice as it results in the shortest reaction times, but di­meth­ylformamide can be replaced by tetrahydrofuran.

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