[C:1]([C:4]1[CH:13]=[C:12]([Cl:14])[C:7]([C:8]([O:10][CH3:11])=[O:9])=[C:6]([Cl:15])[CH:5]=1)(=O)[NH2:2].FC(F)(F)C(OC(=O)C(F)(F)F)=O.N1C=CC=CC=1>O>[Cl:14][C:12]1[CH:13]=[C:4]([C:1]#[N:2])[CH:5]=[C:6]([Cl:15])[C:7]=1[C:8]([O:10][CH3:11])=[O:9]A mixture of methyl 4-carbamoyl-2,6-dichlorobenzoate (57 g, 230 mmol), trifluoroacetic anhydride (46 mL) and pyridine (46 mL) in dixoane (400 mL) was stirred at room temperature for 24 hours, diluted with water (300 mL) and extracted with ethyl acetate (3×300 mL). The combined organic extracts were washed with brine (200 mL), dried over Na2SO4, and concentrated under reduced pressure. The residue was purified by column chromatography on silica gel, eluting with petroleum-diethyl ether (10:1) to give methyl 2,6-dichloro-4-cyanobenzoate (32 g, yield: 61%) as a pale yellow solid. 1H NMR (400 MHz, DMSO-d6) δ 3.91 (s, 3H), 7.95 (s, 2H). LCMS (ESI) m/z: 230.1 [M+H+].
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