[NH2:1][C:2]1[CH:7]=[C:6]([Cl:8])[N:5]=[C:4]([C:9]([O:11][CH3:12])=[O:10])[C:3]=1[Cl:13].[I:14](O)(=O)(=O)=O.II>CO>[NH2:1][C:2]1[C:7]([I:14])=[C:6]([Cl:8])[N:5]=[C:4]([C:9]([O:11][CH3:12])=[O:10])[C:3]=1[Cl:13]Methyl 4-amino-3,6-dichloropicolinate (10.0 g, 45.2 millimoles (mmol)), periodic acid (3.93 g, 17.2 mmol), and iodine (11.44 g, 45.1 mmol) were dissolved in methanol (30 mL) and stirred at reflux at 60° C. for 27 h. The reaction mixture was concentrated, diluted with diethyl ether, and washed twice with saturated aqueous sodium bisulfate. The aqueous layers were extracted once with diethyl ether, and the combined organic layers were dried over anhydrous sodium sulfate. The product was concentrated and purified by flash chromatography (silica gel, 0-50% ethyl acetate/hexanes) to provide the title compound as a pale yellow solid (12.44 g, 79%): mp 130.0-131.5° C.; 1H NMR (400 MHz, CDCl3) δ 5.56 (s, 2H), 3.97 (s, 3H); 13C NMR (101 MHz, CDCl3) δ 163.80, 153.00, 152.75, 145.63, 112.12, 83.91, 53.21; EIMS m/z 346.
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