Cl[Si](C)(C)C.Br[CH2:7][C:8]([O:10][C:11]([CH3:14])([CH3:13])[CH3:12])=[O:9].[F:15][C:16]1[C:23]([CH3:24])=[CH:22][CH:21]=[C:20]([F:25])[C:17]=1[CH:18]=[O:19]>O1CCCC1.[Zn]>[F:15][C:16]1[C:23]([CH3:24])=[CH:22][CH:21]=[C:20]([F:25])[C:17]=1[CH:18]([OH:19])[CH2:7][C:8]([O:10][C:11]([CH3:14])([CH3:13])[CH3:12])=[O:9]To a suspension of zinc (1.256 g, 19.21 mmol) in dry tetrahydrofuran (18 mL) was added chlorotrimethylsilane (1.228 mL, 9.61 mmol). After 20 min, tert-butyl 2-bromoacetate (1.420 mL, 9.61 mmol) was added. The reaction was stirred at rt for 10 min, then heated at 40° C. for 20 min. The reaction mixture was cooled to 0° C. under Ar, and 2,6-difluoro-3-methylbenzaldehyde (1.5 g, 9.61 mmol) in 3 mL of dry THF was added. The reaction was allowed to warm to rt and stirred overnight. The reaction mixture was quenched with 5% aqueous NaHCO3, filtered, and rinsed with EtOAc. The filtrate was washed with water and brine, dried over MgSO4, filtered, concentrated and purified by silica gel chromatography to yield the desired product (1.46 g, 56%). MS (ESI) m/z: 295.1 (M+Na)+.
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