C[Si]([N-][Si](C)(C)C)(C)C.[Li+].[CH3:11][O:12][C:13]1[CH:30]=[CH:29][C:28]2[C@@H:27]3[C@H:18]([C@@:19]45[CH2:32][C@@H:20]4[CH2:21][C:22](=[O:31])[C@:23]5([CH2:25][CH2:26]3)[CH3:24])[C@H:17]([CH3:33])[CH2:16][C:15]=2[CH:14]=1.I[CH3:35].[Cl-].[NH4+]>O1CCCC1>[CH3:11][O:12][C:13]1[CH:30]=[CH:29][C:28]2[C@@H:27]3[C@H:18]([C@@:19]45[CH2:32][C@@H:20]4[C@@H:21]([CH3:35])[C:22](=[O:31])[C@:23]5([CH2:25][CH2:26]3)[CH3:24])[C@H:17]([CH3:33])[CH2:16][C:15]=2[CH:14]=1i)—A solution of lithium bis(trimethylsilyl)amide (20.2 mmol) in tetrahydrofuran (35 ml) was cooled to −40° C. A solution of (7α,14β,15β)-3-methoxy-7-methyl-14,15-methyleneestra-1,3,5 (10)-trien-17-one (Example 1, step ii; 5.60 g) in dry tetrahydrofuran (24 ml) was added dropwise and the reaction mixture was stirred for 30 min. Then, at −30° C., iodomethane (2.4 ml) was added and stirring was continued for 45 min. The mixture was poured into a saturated aqueous solution of ammonium chloride and the product was extracted into ethyl acetate. The combined organic phases were washed with brine, dried over sodium sulfate and concentrated under reduced pressure, to give (7α,14β,15β,16α)-3-methoxy-7,16-dimethyl-14,15-methyleneestra-1,3,5(10)-trien-17-one (5.99 g). The product was used in the following step without further purification.
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