[Br:1][C:2]1[CH:15]=[CH:14][C:5](/[CH:6]=[N:7]/[S@@:8]([C:10]([CH3:13])([CH3:12])[CH3:11])=[O:9])=[CH:4][CH:3]=1.[C:16]1([Mg]Br)[CH:21]=[CH:20][CH:19]=[CH:18][CH:17]=1>C1COCC1>[Br:1][C:2]1[CH:15]=[CH:14][C:5]([C@@H:6]([C:16]2[CH:21]=[CH:20][CH:19]=[CH:18][CH:17]=2)[NH:7][S@:8]([C:10]([CH3:11])([CH3:12])[CH3:13])=[O:9])=[CH:4][CH:3]=1(R,E)-N-(4-bromobenzylidene)-2-methylpropane-2-sulfinamide, 18-b, (10 g, 34.84 mmol) was dissolved in anhydrous THF (100 ml). The mixture was then cooled to −45° C. and PhMgBr (34.84 ml, 69.68 mmol) was added dropwise. After addition, the mixture was allowed to stir at −45° C. for additional 4 h and warm to room temperature for another 2 h. TLC monitored the reaction and the time was prolonged if necessary. The mixture was quenched with saturated NH4Cl followed by extraction with ethyl acetate. The organic layer was dried over sodium sulfate and concentrated under vacuum. The residue was purified by column chromatography (petroleum ether/ethyl acetate=4/1) to provide the product, 22-a, (8 g, 63%). HPLC indicated that the diastereomer ratio is 96:4 after recrystallization once in hexane/ethyl acetate.
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