[Br:1][C:2]1[CH:7]=[CH:6][C:5](/[CH:8]=[N:9]/[S@:10]([C:12]([CH3:15])([CH3:14])[CH3:13])=[O:11])=[C:4]([F:16])[CH:3]=1.[CH3:17][Mg]Cl>C(Cl)Cl>[Br:1][C:2]1[CH:7]=[CH:6][C:5]([C@H:8]([NH:9][S@:10]([C:12]([CH3:13])([CH3:15])[CH3:14])=[O:11])[CH3:17])=[C:4]([F:16])[CH:3]=1To a solution of (S)-2-methyl-propane-2-sulfinic acid 1-(4-bromo-2-fluoro-phenyl)-meth-(E)-ylideneamide (4.5 g, 14.7 mmol) in DCM (80 ml) was added methylmagnesium chloride (7.35 ml, 22.0 mmol, 3M solution in ether) dropwise at −48° C. After 1 h additional methylmagnesium chloride (2.45 ml, 7.35 mmol, 3M solution in ether) was added dropwise and the reaction mixture was stirred at −48° C. for 6 h. The reaction was then quenched by addition of sat. NH4Cl solution and the mixture was extracted three times with DCM. The combined organic layers were dried with Na2SO4 and evaporated. The remaining white solid was purified by chromatography (silica gel; heptane/EtOAc 2:1-1:1) to obtain the title compound as white solid (3.89 g, 82%).
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