[CH3:1][O:2][C:3](=[O:13])[C:4]1[CH:9]=[C:8]([CH3:10])[C:7]([O:11][CH3:12])=[N:6][CH:5]=1.C1C(=O)N([Br:21])C(=O)C1.CC(N=NC(C#N)(C)C)(C#N)C>C(Cl)(Cl)(Cl)Cl>[CH3:1][O:2][C:3](=[O:13])[C:4]1[CH:9]=[C:8]([CH2:10][Br:21])[C:7]([O:11][CH3:12])=[N:6][CH:5]=1A solution containing 6-methoxy-5-methyl-nicotinic acid methyl ester (4.00 g, 22.1 mmol), NBS (5.11 g, 28.7 mmol), and AIBN (0.90 g, 5.5 mmol) in CCl4 (100 mL) is warmed to reflux. After 5 h, the reaction mixture is cooled and then concentrated in vacuo. The residue is dissolved in EtOAc (500 mL) and washed successively with aqueous Na2S2O3 (300 mL), water (100 mL), brine then dried over anhydrous Na2SO4, filtered and concentrated. The crude product is purified by silica gel flash column chromatography (hexane/diethyl ether, 9:1) to provide 3.10 g (54%) of the title compound as a white solid. 1H NMR (300 MHz, CDCl3) δ3.90 (s, 3H), 4.07 (s, 3H), 4.46 (s, 2H), 8.19 (d, J=2.2 Hz, 1H), 8.79 (d, J=2.2 Hz, 1H) ppm; MS (EI): m/z 259 (M+).
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