[F:1][C:2]1[C:7]([F:8])=[CH:6][C:5]([OH:9])=[C:4]([O:10][CH3:11])[CH:3]=1.C(N(CC)C(C)C)(C)C.[Si:21](Cl)([C:24]([CH3:27])([CH3:26])[CH3:25])([CH3:23])[CH3:22].CN(C1C=CC=CN=1)C>C(Cl)Cl>[C:24]([Si:21]([O:9][C:5]1[CH:6]=[C:7]([F:8])[C:2]([F:1])=[CH:3][C:4]=1[O:10][CH3:11])([CH3:23])[CH3:22])([CH3:27])([CH3:26])[CH3:25]
To a solution of 4,5-difluoro-2-methoxy-phenol (3.75 g, 23.42 mmol, Example 264) in methylene chloride (60 mL) cooled to 0° C. were added N,N-diisopropylethylamine (4.895 mL, 28.10 mmol), tert-butyldimethylsilyl chloride (4.367 g, 28.10 mmol, Aldrich), and dimethylaminopyridine (286 mg, 2.342 mmol, Aldrich). At the end of addition, the ice bath was removed and the reaction mixture was stirred at room temperature for 90 minutes. Water (30 mL) was added and the layers were separated. The aqueous layer was extracted with methylene chloride (20 mL). The combined organic layers were washed with brine and dried over anhydrous magnesium sulfate. The solids were filtered off and the filtrate was concentrated in vacuo. Purification of the crude residue by flash chromatography (Biotage system, 60 Å silica gel, eluting with 3% ethyl acetate in hexanes) yielded tert-butyl-(4,5-difluoro-2-methoxy-phenoxy)-dimethyl-silane as a clear oil (5.22 g, 81%).
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