Electrochemical chlorination of some 5-unsaturated steroids

Abstract

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? -dichlorosteroids, in good yields (70?73 %). The obtained compounds (5?,6? -dichlorocholestane, 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 amixture of products from which the expected dichloro derivative (3 ? -hydroxy- 5 ?,6 ? -dichlorocholestane) could not be isolated. This compound was prepared by alkaline hydrolysis of 5?,6?-dichlorocholestan-3? -yl acetate and 5?,6? -dichlorocholestan- 3? -yl benzoate in methanol.