Ammonium Chloride → 4,4-Di methyl-5alpha-cholesta-8,14,24-trien-3-one

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A solution of isopropyltriphenylphosphorane was prepared by addition of BuLi (0.16 ml of 1.6M in hexanes, 0.26 mmol) to a suspension of isopropyltriphenylphosphonium bromide (98 mg, 0.26 mmol) in THF (2 mL) at ice bath temperature. The corresponding deep red phosphorane solution was stirred a further 0.5 hour and then added dropwise via syringe to a solution of 3-oxo-4,4-dimethyl-5α-chola-8,14-dien-24-aldehyde (71 mg, 0.18 mmol) in THF (2ml) at −78° C. and stirred 2 hours before slowly warming to room temperature and stirring overnight. Saturated ammonium chloride (3 mL) was added and the aqueous phase extracted using diethyl ether, and the organic phase dried over anhydrous sodium sulphate. Flash chromatography (Eluant: 6 hexane: 1 ethyl acetate) gave the title compound (38 mg, 50%).

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