[F:1][C:2]1[CH:3]=[C:4]([Cl:9])[CH:5]=[C:6]([F:8])[CH:7]=1.CN(C)CCN(C)C.C([Li])CCC.[CH3:23][Si:24](Cl)([CH3:26])[CH3:25].[Cl-].[NH4+]>C1COCC1>[Cl:9][C:4]1[CH:3]=[C:2]([F:1])[C:7]([Si:24]([CH3:26])([CH3:25])[CH3:23])=[C:6]([F:8])[CH:5]=1To a solution of 3,5-difluoro-1-chlorobenzene (10.0 g, 67 mmol) and tetramethylethlenediamine (TMEDA; 7.8 g, 67 mmol) in THF (75 mL) at −75° C., was added n-butyl lithium (2.5M, 68 mmol) and the resulting solution stirred for 30 minutes. A solution of trimethylsilyl chloride (7.6 g, 70 mmol) in THF (15 mL) was added and the solution allowed to warm to ambient temperature and stir for 25 hours. Ammonium chloride (saturated solution 15 mL) was added and the mixture extracted with ethyl ether (2×100 mL) and the combined extracts washed with brine, dried (sodium sulfate) and concentrated. The residual oil was distilled to give 1-chloro-3,5-difluoro-4-trimethylsilylbenzene (13.0 g, 60 mmol): bp 70-75° C.
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