Electrochemical chlorination of some 5-unsaturated steroids

Five 5-unsaturated steroids were subjected to constant current electrolysis (50 mA) in a dichloromethane solution of tetraethylammonium chloride in an undivided electrolytic cell at room temperature, using a graphite stick as the anode and a cooper spiral as the cathode. The addition of electrochemically generated elemental chlorine onto the double bond of cholesterol derivatives (5-cholestene, cholesteryl acetate, cholesteryl benzoate and 3-chloro-5-cholstene) gave the corresponding 5,6-dichloro- steroids, in good yields (70-73 %). The obtained compounds (5,6-dichlorocholesta- ne, 5,6-dichlorocholestane-3-yl acetate, 5,6-dichlorocholestane-3-yl benzoate and 3,5,6-trichlorocholestane) were characterized by physical and spectral data (IR, 1 H-NMR and 13 C-NMR). However, under the same reaction conditions, cholesterol produced a mixture of products from which the expected dichloro derivative (3-hydro- xy-5,6-dichlorocholestane) could not be isolated. This compound was prepared by alkaline hydrolysis of 5,6-dichlorocholestan-3-yl acetate and 5,6-dichlorochole- stan-3-yl benzoate in methanol.