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 5α,6β-dichlorosteroids, in good yields (70-73 %). The obtained compounds (5α,6β- dichlorocholestane, 5α,6β-dichlorocholestane-3β-yl acetate, 5α,6β-dichlorocholestane-3β-yl benzoate and 3β,5α, 6β-trichlorocholestane) were characterized by physical and spectral data (IR, 1H-NMR and 13C-NMR). However, under the same reaction conditions, cholesterol produced a mixture of products from which the expected dichloro derivative (3β-hydroxy-5α,6β-dichlorocholestane) could not be isolated. This compound was prepared by alkaline hydrolysis of 5α,6β-dichlorocholestan-3β-yl acetate and 5α,6β- dichlorocholestan-3β-yl benzoate in methanol.