[CH3:1]C(C)([O-])C.[K+].[CH3:7][C@@:8]12[C:24](=O)[CH2:23][CH2:22][C@H:21]1[C@H:20]1[C@@H:11]([C:12]3[CH:13]=[CH:14][C:15]([OH:26])=[CH:16][C:17]=3[CH2:18][CH2:19]1)[CH2:10][CH2:9]2>[Br-].C[P+](C1C=CC=CC=1)(C1C=CC=CC=1)C1C=CC=CC=1.C1COCC1>[CH2:1]=[C:24]1[CH2:23][CH2:22][C@H:9]2[C@H:10]3[C@H:11]([CH2:20][CH2:21][C@:8]12[CH3:7])[C:12]1[CH:13]=[CH:14][C:15]([OH:26])=[CH:16][C:17]=1[CH2:18][CH2:19]3To a suspension of methyl triphenylphosphonium bromide (8.93 g, 25.0 mmol) in THF (120 mL) was added potassium tert-butoxide (2.69 g, 24 mmol) and stirred for 30 min at room temperature. The reaction mixture was added estrone (18, 2.70 g, 10 mmol), stirred for 19 h at room temperature. The reaction mixture was quenched with saturated aqueous NH4Cl at 0° C. and extracted with EtOAc. The combined organic layers were washed with H2O, then with saturated aqueous NaCl, and dried (Na2SO4). The desiccant was filtered and the solvent was evaporated at reduced pressure. The residue was purified by column chromatography (silica gel) using n-hexane:EtOAc (5:1→3:1, v/v) to afford 2.24 g of 19 (84% yield), m.p. 135°-136° C.
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