Br[C:2]1[CH:7]=[CH:6][C:5]([F:8])=[CH:4][CH:3]=1.[Li]CCCC.[Br:14][C:15]1[CH:28]=[CH:27][C:18](/[CH:19]=[N:20]/[S@:21]([C:23]([CH3:26])([CH3:25])[CH3:24])=[O:22])=[CH:17][CH:16]=1>C1COCC1>[Br:14][C:15]1[CH:16]=[CH:17][C:18]([C@H:19]([C:2]2[CH:7]=[CH:6][C:5]([F:8])=[CH:4][CH:3]=2)[NH:20][S@:21]([C:23]([CH3:26])([CH3:25])[CH3:24])=[O:22])=[CH:27][CH:28]=1The solution of 1-bromo-4-fluorobenzene (66.7 g, 0.38 mol) in THF (400 mL) was cooled to −78° C. Then n-BuLi (140 mL, 0.38 mol) was dropwise added at −78° C. and maintained at this temperature for about 1 h. (S,E)-N-(4-bromobenzylidene)-2-methylpropane-2-sulfinamide, 19-a, (70 g, 0.19 mol) in anhydrous THF (100 ml) was also dropwise added at −78° C. The mixture was stirred at −78° C. for 1 h, warmed to rt for 2 h, and then quenched by NH4Cl aq. The organic phase was dried and purified by column chromatography (PE:EA=10:1) afford the product 19-b as a light yellow solid, recrystallized by PE:EA=20:1 to give the white solid, (26 g, 35%).
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