[Li+].[Cl-].[Br:3][C:4]1[CH:5]=[N:6][C:7]([F:18])=[C:8]([C:16]=1[F:17])[C:9]([O:11][C:12]([CH3:15])([CH3:14])[CH3:13])=[O:10].[Br:19]C(Br)(F)C(F)(F)F>C1COCC1>[Br:3][C:4]1[C:5]([Br:19])=[N:6][C:7]([F:18])=[C:8]([C:16]=1[F:17])[C:9]([O:11][C:12]([CH3:14])([CH3:15])[CH3:13])=[O:10]Into a solution of TMPMgCl LiCl (1.0 M×6.8 mL, 6.8 mmol) in THF (5.0 mL) at −45° C. was added dropwise a solution of tert-butyl 5-bromo-2,4-difluoronicotinate (1.32 g, 4.5 mmol) in THF (5.0 mL). The mixture was stirred for 15 min then dibromotetrafluoroethane (1.0 mL, 6.8 mmol) was added. After 15 min at −45° C., the temperature was allowed to rise to room temperature. The reaction was quenched with saturated NH4Cl and extracted with ethyl acetate. The organic layers were combined, dried over sodium sulfate and evaporated. The residue was purified by silica chromatography (0-10% ethyl acetate in hexanes) to give tert-butyl 5,6-dibromo-2,4-difluoronicotinate (1.29 g, 77%).
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