[F:1][C:2]1[CH:16]=[CH:15][C:14]([F:17])=[CH:13][C:3]=1[CH2:4]P(=O)(OCC)OCC.[Br:18][C:19]1[CH:20]=[N:21][CH:22]=[C:23]([CH:26]=1)[CH:24]=O.CC(C)([O-])C.[K+].CCCCCC>O1CCCC1.CCOCC>[Br:18][C:19]1[CH:20]=[N:21][CH:22]=[C:23](/[CH:24]=[CH:4]/[C:3]2[CH:13]=[C:14]([F:17])[CH:15]=[CH:16][C:2]=2[F:1])[CH:26]=1
To a stirred solution of diethyl 2,5-difluorobenzylphosphonate (63.5 g, 240 mmol) and 5-bromonicotinaldehyde (50.7 g, 264 mmol) in tetrahydrofuran (1923 ml) was added potassium tert-butoxide in tetrahydrofuran (312 ml, 312 mmol) at −10° C. After three hours, the reaction mixture was allowed to warm to ambient temperature and stirring was continued for another 16 hours at which time the reaction mixture was diluted with ether (800 mL) and washed with H2O. The organic layer was dried over anhydrous magnesium sulfate, filtered and concentrated to provide a yellow wax to which was added 300 mL of hexane and after sonication filtered to provide (E)-3-bromo-5-(2,5-difluorostyryl)pyridine (54 g, 173 mmol, 72.1%) as a white solid. 1H NMR (500 MHz, DMSO-d6) δ 8.78 (d, J=1.8 Hz, 1H), 8.63 (d, J=2.1 Hz, 1H), 8.44 (t, J=2.0 Hz, 1H), 7.67 (ddd, J=9.4, 6.0, 3.2 Hz, 1H), 7.56-7.48 (m, 1H), 7.46-7.40 (m, 1H), 7.34 (td, J=9.6, 4.6 Hz, 1H), 7.24 (tt, J=8.3, 3.6 Hz, 1H). MS Anal. Calcd. for [M+H]+ C13H9BrF2N: 296.0. found 298.1.
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