Cl[C:2]1[N:3]=[CH:4][C:5]([C:9]([O:11][CH3:12])=[O:10])=[N:6][C:7]=1[CH3:8].[F:13][C:14]([F:18])([F:17])[CH2:15][OH:16].C(=O)([O-])[O-].[K+].[K+]>CN(C=O)C>[CH3:8][C:7]1[N:6]=[C:5]([C:9]([O:11][CH3:12])=[O:10])[CH:4]=[N:3][C:2]=1[O:16][CH2:15][C:14]([F:18])([F:17])[F:13]A mixture of methyl 5-chloro-6-methylpyrazine-2-carboxylate (3.00 g, 16.1 mmol), 2,2,2-trifluoroethanol (32.2 g, 322 mmol), and potassium carbonate (3.33 g, 24.1 mmol) in DMF (30 mL) is stirred at 60° C. for 2 hours. After cooling to rt, the mixture is filtered off, and the filtrate is diluted with EtOAc (300 mL). The organic layer is washed with water (100 mL×3) and dried over sodium sulfate. After filtration, the filtrate is concentrated in vacuo. The residue is purified by column chromatography on silica gel eluting EtOAc to give 3.91 g (97% yield) of the title compound as white solid.
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