[C:1]([O:6][CH2:7][CH3:8])(=[O:5])[CH:2]([CH3:4])[CH3:3].C[Si]([N-][Si](C)(C)C)(C)C.[Li+].Br[CH2:20][C:21]1[CH:26]=[CH:25][C:24]([F:27])=[CH:23][CH:22]=1>O1CCCC1>[CH2:7]([O:6][C:1](=[O:5])[C:2]([CH3:4])([CH3:3])[CH2:20][C:21]1[CH:26]=[CH:25][C:24]([F:27])=[CH:23][CH:22]=1)[CH3:8]A solution of ethyl isobutyrate (11.03 g, 95 mmol) in tetrahydrofuran (75 mL) was added dropwise to a mixture of a solution of lithium bis(trimethylsilyl)amide in tetrahydrofuran (1.0 M, 100 mL, 100 mmol) and tetrahydrofuran (100 mL) at −78° C. over 15 minutes. The resulting solution was stirred at −78° C. for 45 minutes, and then treated with a solution of 1-bromomethyl-4-fluorobenzene (11.5 mL, 92 mmol) in tetrahydrofuran (25 mL) over 5 minutes. The cooling bath was removed, and the reaction mixture was stirred for 18 hours at room temperature. 1.0 N aqueous hydrochloric acid was added, and the layers were separated. The aqueous phase was extracted with ethyl acetate, and the combined organic phases were washed with 1.0 N aqueous hydrochloric acid, dried over sodium sulfate, and concentrated under vacuum to provide a brown liquid (20.7 g, quantitative) used without further purification. 1H NMR (300 MHz, CDCl3) δ7.07 (m, 2H), 6.94 (t, J=9 Hz, 2H), 4.10 (q, J=7 Hz, 2H), 2.82 (s, 2H), 1.23 (t, J=7 Hz, 3H), 1.16 (s, 6H).
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