[C:1]([NH:4][C:5]1[CH:6]=[C:7]([CH:14]=[C:15]([S:17]([F:22])([F:21])([F:20])([F:19])[F:18])[CH:16]=1)[C:8](N(OC)C)=[O:9])(=[O:3])[CH3:2].[CH3:23][Si](C)(C)[N-][Si](C)(C)C.[Li+].COCCCC.C[Mg]Br.Cl>C1COCC1.C(OCC)(=O)C.O>[C:8]([C:7]1[CH:6]=[C:5]([NH:4][C:1](=[O:3])[CH3:2])[CH:16]=[C:15]([S:17]([F:22])([F:18])([F:20])([F:21])[F:19])[CH:14]=1)(=[O:9])[CH3:23]3-Acetylamino-N-methoxy-N-methyl-5-(pentafluorosulfanyl)benzamide (1.2 g) was dissolved in absolute THF (30 ml) and stirred at 0° C. with lithium hexamethyldisilazide (721 μl; density: 0.8 g/1; 23% in tent-butyl methyl ether) for 30 min. At 0° C., methylmagnesium bromide (2.87 ml, 3 M in diethyl ether) was then added dropwise while stirring. After stirring at RT for 2.5 h, further methylmagnesium bromide (1 ml, 3 M in diethyl ether) was added and the mixture was stirred again for 2.5 h. For workup, 1 N hydrochloric acid was added dropwise while cooling with ice, followed by water and ethyl acetate. The organic phase was removed and the water phase was extracted twice more with ethyl acetate. The combined ethyl acetate phases were dried over sodium sulfate, filtered and concentrated. The crude product (1.03 g) was combined with a crude product prepared in the same way (75 mg) and purified using silica gel with dichloromethane-methanol as the eluent. 860 mg of the desired compound were obtained. LC-MS rt: 1.34 min [M+H]+: 304.0
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