Pyridine → 3alpha-Trifluoroacetoxy-5alpha-pregnane-11,20-dione

Participants

Reaction Steps

A solution of trifluoroacetic anhydride (0.34 ml.) and pyridine (0.24 ml.) in methylene dichloride (10 ml.) was added to a cooled (-80°) and stirred solution of 3α-hydroxy-5α-pregnane-11,20-dione (0.50 g.) in methylene dichloride (20 ml.) and the mixture was allowed to warm up to room temperature. After 11/2 hours more trifluoroacetic anhydride (0.34 ml.) was added and the reaction was complete after 1/2 hour more. The solution was washed successively with water, sodium bicarbonate solution and water. The dried and concentrated solution afforded a crystalline residue that was triturated with petroleum to give the title compound as needles (0.44 g.) m.p. 107°-108°, [α]D + 96°.

Provenance & Evidence