[Li+].CC([N-]C(C)C)C.[F:9][C:10]1[N:22]=[CH:21][CH:20]=[C:19]([F:23])[C:11]=1[C:12]([O:14][C:15]([CH3:18])([CH3:17])[CH3:16])=[O:13].[Cl:24]C(Cl)(Cl)C(Cl)(Cl)Cl>C1COCC1>[Cl:24][C:20]1[CH:21]=[N:22][C:10]([F:9])=[C:11]([C:19]=1[F:23])[C:12]([O:14][C:15]([CH3:18])([CH3:17])[CH3:16])=[O:13]Into a solution of LDA in THF (20 mL, 12 mmol) was added a solution of tert-butyl 2,4-difluoronicotinate (2.14 g, 10 mmol) in THF (12 mL) at −78° C. The mixture was stirred for 30 min and then a solution of hexachloroethane (2.96 g, 12.5 mmol) in THF (7.0 mL) was added. The temperature was allowed to rise to 0° C. The reaction was then quenched with saturated NH4Cl. The mixture was extracted with ethyl acetate and the organic layers were combined, dried over sodium sulfate, evaporated and purified by silica chromatography (0-8% ethyl acetate in hexanes) to give tert-butyl 5-chloro-2,4-difluoronicotinate (1.2 g, 48%).
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