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

Participants

Reaction Steps

A solution of trichloroacetyl chloride (0.5 ml.) in dry tetrahydrofuran (8 ml.) was added dropwise to a cooled (-80°) and stirred solution of 3α-hydroxy-5α-pregnane-11,20-dione (0.75 g.) and pyridine (0.35 ml.) in dry tetrahydrofuran (15 ml.). After 30 min. the mixture was concentrated in vacuo and the residue was partitioned between ethyl acetate and water. The organic layer was washed with 2N-hydrochloric acid, aqueous sodium hydrogen carbonate, then water. The solution was dried and concentrated to leave a residue which was crystallised from benzene then benzene-petrol to afford the title compound (0.21 g.), m.p. 126°-127°, [α]D + 86°.

Provenance & Evidence