5alpha-Cholestan-3-one → 3beta-(3-Methanesulfonyloxy-1-Azetidinyl)-5alpha-Cholestane

関与物質

反応手順

To a stirred suspension of 3.50 g of the mesylate salt of 3-methanesulfonyloxyazetidine (m.p. 111.5°-113° C. dec.) and 5.46 g of 5α-cholestan-3-one in 100 ml of anhydrous methanol maintained at room temperature under a nitrogen atmosphere add 1.74 g sodium cyanoborohydride portionwise over a 20 minute period. Stir for 30 minutes at room temperature, pour into 600 ml water, add to the mixture 100 ml 1.1 M aqueous sodium bicarbonate and extract three times with ethyl ether. Combine the ether extracts, dry over 3 A molecular sieves and remove solvent in vacuo to give a mixture of α- and β-mesylates. Chromatography of this mixture on 150 g Stahl-type silica using ethyl acetate affords the pure title product (slower-moving component), m.p., 135.5° C. dec., [α]D26 =+12.1° (CHCl3, 0.4%).

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