A
100-ml., round-bottomed flask equipped with a reflux condenser is charged with
1.00 g. (0.00345 mole) of 5α-androstan-17β-ol-3-one (Note
1),
0.90 g. (0.0048 mole) of tosylhydrazide (Note
2), and
70 ml. of methanol (Note
3). The mixture is heated under gentle reflux for 3 hours, then cooled to room temperature. To the solution is added
2.5 g. (0.075 mole) of sodium borohydride in small portions over one hour (Note
4) and the resulting mixture is heated under reflux for an additional 8 hours. The reaction mixture is cooled to room temperature before the solvent is removed under reduced pressure. The residue is dissolved in
diethyl ether, transferred to a
separatory funnel, and washed successively with water,
dilute aqueous sodium carbonate,
2 M hydrochloric acid, and water. The ethereal solution is dried over
anhydrous sodium sulfate and evaporated under reduced pressure. The residue, 0.95 g. of white crystals (Note
5), is dissolved in about
20 ml. of a 7:3 (v/v) mixture of cyclohexane-ethyl acetate and applied to a
column packed with 60 g. of silica gel (Merck, 0.05–0.2 mm.). The column is eluted with the
7:3 (v/v) cyclohexane-ethyl acetate mixture and a 200-ml. fraction is collected. Evaporation of this fraction under reduced pressure affords
0.70–0.73 g. (
73–76%) of pure
5α-androstan-17β-ol. Recrystallization from
aqueous methanol provides
0.64 g. of analytically pure product, m.p.
161–163°.