[O:1]1[C@H:3]2[CH2:4][C@H:5]3[C@:20]([CH3:22])([CH2:21][C@@H:2]12)[C@@H:19]1[C@H:8]([C@H:9]2[C@:16]([CH3:23])([CH2:17][CH2:18]1)[C@@H:12]([C:13](=[O:15])[CH3:14])[CH2:11][CH2:10]2)[CH2:7][CH2:6]3.C(=O)(O)[O-].[Na+].[CH2:29]([OH:31])[CH3:30]>S(=O)(=O)(O)O>[CH2:29]([O:31][C@H:2]1[CH2:21][C@@:20]2([CH3:22])[C@@H:5]([CH2:6][CH2:7][C@@H:8]3[C@@H:19]2[CH2:18][CH2:17][C@@:16]2([CH3:23])[C@H:9]3[CH2:10][CH2:11][C@@H:12]2[C:13](=[O:15])[CH3:14])[CH2:4][C@@H:3]1[OH:1])[CH3:30]2α,3α-Epoxy-5α-pregnan-20-one (180 mg) was dissolved in 20 mL of absolute ethanol and cooled to °C. and added to a cold 1.0 mL ethanol solution containing 3-drops of concentrated sulfuric acid. This reaction mixture was stirred for 30 minutes at this temperature and an additional 30 minutes at room temperature, poured into 20% sodium bicarbonate solution and washed several times with chloroform. The combined organic phase was dried over potassium carbonate and concentrated and purified by preparative TLC silica plate in hexane/ethyl acetate (1:1), to give (80 mg, 40% yield) the title compound as fine white crystals.
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