Br[C:2]1[CH:15]=[C:14]([Cl:16])[C:5]([O:6][Si:7]([C:10]([CH3:13])([CH3:12])[CH3:11])([CH3:9])[CH3:8])=[C:4]([Cl:17])[CH:3]=1.[Li]CC[CH2:21][CH3:22].[OH2:23]>C(OCC)C.C1COCC1>[Si:7]([O:6][C:5]1[C:14]([Cl:16])=[CH:15][C:2]([C:21](=[O:23])[CH3:22])=[CH:3][C:4]=1[Cl:17])([C:10]([CH3:13])([CH3:12])[CH3:11])([CH3:9])[CH3:8]To a solution of (4-bromo-2,6-dichlorophenoxy)(tert-butyl)dimethylsilane (from step 1, 15.2 g, 42.7 mmol) in diethyl ether (100 mL), n-BuLi (1.57 M in n-hexane, 27.2 mL, 42.7 mmol) was added at −78° C. and the mixture was stirred for 1 h. N,N′-dimethylacetamide (4.2 mL, 44 mmol) in THF (20 mL) was added at −78° C. and the mixture was stirred for 2 hours. The mixture was added water (100 mL) and extracted with diethyl ether (50 mL×3), dried over MgSO4 and concentrated in vacuo. The residue was purified by flash chromatography eluting with ethyl acetate-hexane (1:10) to give title compound as a pale yellow oil (4.7 g, 34%).
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