Br[C:2]1[CH:7]=[CH:6][C:5]([Br:8])=[CH:4][N:3]=1.C([Li])CCC.C([O:16][C:17](=O)[C:18]([F:21])([F:20])[F:19])C>O1CCCC1.C1(C)C=CC=CC=1.[Cl-].[NH4+]>[Br:8][C:5]1[CH:6]=[CH:7][C:2]([C:17](=[O:16])[C:18]([F:21])([F:20])[F:19])=[N:3][CH:4]=1To a stirred solution of 2, 5-Dibromo-pyridine (4 g, 6.87 mmol) in dry tetrahydrofuran (30 mL) and dry toluene (40 mL) is added drop wise n-Butyl lithium (1.62 g, 25.31 mmol) at −78° C. After stirring for 15-20 minutes, added trifluoro-acetic acid ethyl ester (3.56 g, 25.31 mmol) at −78° C. then stirred at −78° C. for another 30 minutes. The reaction mixture is diluted with saturated ammonium chloride solution and extracted with ethyl acetate. Organic layer is dried over sodium sulphate, solvent is evaporated in vacuo and purified by column chromatography eluting in 20% ethyl acetate in hexane to afford the title compound (1.2 g). 1HNMR (400 MHz, DMSO-d6) δ: 7.72 (d, J=8.32 Hz, 1H), 7.85-7.88 (dd, J1=8.32 Hz, J2=2.44 Hz 1H), 8.52 (d, J=2.36 Hz, 1H). LC-MS (m/z): [M+H]=255.8.
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