C(N1C=CN=C1)(N1C=CN=C1)=O.[Br:13][C:14]1[CH:15]=[C:16]([CH:20]=[CH:21][C:22]=1[Cl:23])[C:17](O)=[O:18].C(N(CC)CC)C.Cl.[CH3:32][NH:33][O:34][CH3:35]>ClCCl.O>[Br:13][C:14]1[CH:15]=[C:16]([CH:20]=[CH:21][C:22]=1[Cl:23])[C:17]([N:33]([O:34][CH3:35])[CH3:32])=[O:18]
Carbonyldiimidazole (7.2 g, 0.045 mol) was added in portions to a stirred suspension of 3-bromo-4-chlorobenzoic acid (10.0 g, 0.042 mol) in dichloromethane (120 mL). The reaction mixture was stirred at room temperature for 30 minutes then at reflux for 30 minutes. Triethylamine (6.3 mL, 0.045 mol) and N,O-dimethylhydroxylamine hydrochloride (4.2 g, 0.043 mol) were added and the reaction mixture was stirred at room temperature overnight, then diluted with water (75 mL) and the layers separated. The aqueous fraction was extracted with dichloromethane (2×50 mL) and the combined organic extracts were washed with citric acid (10%; 2×50 mL), NaHCO3 (50 mL) and brine (50 mL), dried (sodium sulfate) and concentrated to give 3-bromo-4-chloro-N-methoxy-N-methylbenzamide as a colourless oil (9.3 g, 79%). 1H NMR (300 MHz; DMSO-d6) 7.98 (1H, s, Ar), 7.60 (1H, d, J 7.2, Ar), 7.48 (1H, d, J 7.2, Ar), 3.54 (3H, s, Me), 3.36 (3H, s, Me).
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