C=[CH:2][C@@H:3]1[C@:20]2([CH3:21])[C@H:6]([C@H:7]3[C@H:17]([CH2:18][CH2:19]2)[C@:15]2([CH3:16])[C:10](=[CH:11][C:12](=[O:22])[CH2:13][CH2:14]2)[C:9](=O)[CH2:8]3)[CH2:5][CH2:4]1.[CH3:24]OC(OC)(C)C.CO.C1(C)C=CC(S(O)(=O)=O)=CC=1>CN(C=O)C>[CH3:24][O:22][C:12]1[CH2:13][CH2:14][C@@:15]2([CH3:16])[C:10](=[CH:9][CH2:8][C@@H:7]3[C@@H:17]2[CH2:18][CH2:19][C@@:20]2([CH3:21])[C@H:6]3[CH2:5][CH2:4][C:3]2=[CH2:2])[CH:11]=1Refer to FIG. 190. To 17-methylenandrost-4-en-3-one (9, 2.0000 g, 7.0314 mmol) in 2,2-dimethoxypropane (9.4 ml, 76 mmol) and DMF (9.4 ml) were added 0.37 ml of anh. methanol and 47.0 mg of p-toluenesulfonic acid. After refluxing 4 h the reaction mixture was allowed to cool and then partitioned between 140 ml of hexanes and 90 ml of water. The organic phase was washed with two 90 ml portions of water+90 ml of brine, dried over magnesium sulfate, and flash filtered through a 30 mm dia.×37 mm high column of silica gel (200-400 mesh). Product continued eluting with 200 ml of hexanes. Concentration of the combined filtrates under reduced pressure and recrystallization of the residue from acetone/methanol gave very slightly yellow platelets (1.5291 g, 5.1231 mmol, 73%), m.p. 97-99° C., homogeneous to TLC (25% ethyl acetate/hexanes on silica gel, Rf 0.72).
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