To a solution of 3β-benzoyloxy-14α-cyano-4,4-dimethyl-5α-cholestan-7-ol (4.5 g, 8 mmole) in pyridine (100 mL) cooled to 0° C. was added methanesulfonyl chloride (2 mL). The reaction mixture was then stirred at 25° C. for 3 hours, poured into ice water, extracted with 4:1 ether/methylene chloride and washed with water The dried, concentrated mesylate was dissolved in collidine (150 mL) and refluxed for 18 hours under argon. The reaction was partitioned between iced HCl and ether/methylene chloride, and the organic extracts were washed with dilute HCl, water, aqueous sodium bicarbonate solution and brine The 6-ene impurity was removed by dissolving the product in methylene chloride, cooling to -78° C. and passing a stream of ozone through the solution until a faint blue color persists The solution was purged with argon and dimethyl sulfide was added and the solution was concentrated in vacuo. The dried, concentrated product was chromatographed over silica gel with 25/1 to 10/1 hexanes in ethyl acetate to afford 3β-benzoyloxy-14α-cyano-4,4-dimethyl-5α-cholest-7-ene (2.1 g, 48%).
