Science of Synthesis

Suffert, J., Science of Synthesis, (2005) 26, 940.

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.

‌Meeeee 888‌ Meeeeeeeeee ee 8β-Meeeeee-88β-eeeeeee-88β-eeeeee-8α-eeeeeee-88-eee[‌888‌]

Meeeeeeeeeee Meeeeeeee

8β-Meeeeee-88β-eeeeeee-88β-eeeeee-8α-eeeeeee-88-eee (‌888‌):[‌888‌]

MeM (8.8 e) eee eeeeeeeee, ee eee eeeeee ee eeeee 8 e, ee e eeeeeee ee e-MeMM (888 eM) eee MMM (888 eM) ee ee. MMM (888 eM) eee M(MMe)8 (88 eM) eeee eeee eeeee eee, eeeee eeeeeee eee eeee ee −88°M, M8 eee eeeeee eeeeeee ee. M eeee ee eee eeeeee ‌888‌ (88 e, 8.888 eee) ee MMM (888 eM) eee eeeee eeee 8–88 eee eee eee eeeeeee ee M8 eee eeeeeeeee eee e eeeeeee 88 eee eeeee eeeeeeeeeee eee eeeeeeeeeee ee eee eeeeeee ee −88°M. M8 eee eeee eeeeeeee ee M8, eee MeMM (8 e) ee MeMM (888 eM) eee M8M (88 eM) eeee eeeee. Meeee eeeeeeeee eee 88 eee ee ee, MeMM (88 eM) eee eeeeeeeeee, eee eee eeeeeee eee eeeeee eeee M8M (8 M). Mee eeeeeeeeeee eeee eeeeee eee eeeeeeeee ee eeeeeeeeee, eeeeee eeee M8M, eee eeeee ee e eeeee ee eee ee 888°M. Mee eeeee eeeeeee eee eeeeeeeeeee ee e eeeeeee ee MeMM (8.8 M) eee MeMMe (888 eM), eee eee eeee eee eeeeeeeeeeee ee eeee eee eeeeeee eeeeee. Meee MeMMe (888 eM) eee eeeee eee eee eeee eee eeeeee ee eeee eee eeeee eeeeeeee; eeeee: 88.8 e (88%); ee 888–888°M (Meeeee eee eeeee).

References

Meeeeee Meeeeeeeeee

• 8.Meeeee-Meee, (8888) M 88e, 8888.
• 8.Meeeee-Meee, (8888) M 88e, 8888.