[Br:1][C:2]1[CH:3]=[CH:4][C:5](F)=[N:6][CH:7]=1.C[Si](C)(C)[N-][Si](C)(C)C.[Na+].[CH3:19][S:20]([CH3:23])(=[O:22])=[O:21]>O1CCCC1>[Br:1][C:2]1[CH:3]=[CH:4][C:5]([CH2:19][S:20]([CH3:23])(=[O:22])=[O:21])=[N:6][CH:7]=15-Bromo-2-fluoro-pyridine (2.00 g) dissolved in tetrahydrofuran (20 mL) was added dropwise to a solution of sodium hexamethyldisilazide (2 mol/L in tetrahydrofuran, 28.5 mL) in tetrahydrofuran (20 mL) cooled to ca. −17° C. Dimethylsulfone (4.30 g) was added and stirring continued in the cooling bath for 1 h. The cooling bath was then removed and the solution was stirred at room temperature for one more h. Aqueous NH4Cl solution and brine were added and the resulting mixture was extracted with ethyl acetate. The combined extracts were dried (MgSO4) and the solvent was evaporated. The residue was treated with little ethyl acetate to precipitate the title compound. Yield: 1.73 g (63% of theory); LC (method 3): tR=2.01 min; Mass spectrum (ESI+): m/z=250/252 (Br) [M+H]+.
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