C(NC(C)C)(C)C.[Li]CCCC.[F:13][C:14]1[CH:19]=[CH:18][C:17]([CH3:20])=[CH:16][C:15]=1[F:21].[CH3:22][Si:23](Cl)([CH3:25])[CH3:24].[NH4+].[Cl-]>C1COCC1.CCCCCC.O>[F:13][C:14]1[C:15]([F:21])=[CH:16][C:17]([CH3:20])=[CH:18][C:19]=1[Si:23]([CH3:25])([CH3:24])[CH3:22]To a solution of diisopropylamine (20.2 g, 0.2 mol) in THF (500 mL) cooled with an ice-water bath was added a solution of n-BuLi in hexane (2.5 M, 80 mL) dropwise for over 30 min. The mixture was stirred in the ice bath for 30 min then cooled to −78° C. A solution of 1,2-difluoro-4-methylbenzene (12.8 g, 0.1 mol) in THF (80 mL) was added dropwise, after 20-30 min, a solution of TMSCl (21.6 g, 0.2 mol) in THF (20 mL) was added dropwise. The mixture was stirred at −78° C. for 2-3 h. Sat. NH4Cl (300 mL) was added to the mixture, diluted with water (200 mL) and extracted with ether. The ether layer was washed with brine and dried over Na2SO4, the solvent was removed to give (2,3-difluoro-5-methylphenyl)trimethylsilane (26 g, 100%), which was used for the next step without purification. 1H NMR (CDCl3) δ 6.90 (m, 2H), 2.40 (s, 3H), 0.33 (s, 9H).
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