Cl.[CH3:2][NH:3][O:4][CH3:5].[Cl:6][C:7]1[CH:8]=[C:9]([CH:13]=[CH:14][C:15]=1[Cl:16])[C:10](Cl)=[O:11].CCN(C(C)C)C(C)C.O>CCOC(C)=O>[Cl:6][C:7]1[CH:8]=[C:9]([CH:13]=[CH:14][C:15]=1[Cl:16])[C:10]([N:3]([O:4][CH3:5])[CH3:2])=[O:11]
N,O-Dimethylhydroxylamine hydrochloride (1.48 kg, 14.9 mol) was suspended in EtOAc (16 L) and warmed to 35° C. A solution of 3,4-dichlorobenzoyl chloride (3.00 kg, 13.9 mol) in EtOAc (8 L) was added, followed by addition of DIPEA (5.45 ml, 31.2 mol) while maintaining the temperature below 40° C. The reaction suspension was stirred for 1 h. When TLC analysis confirmed reaction completion by the disappearance of starting material, the reaction mixture was cooled to rt and H2O (10 L) was added to achieve a clear, biphasic solution. After removing the aqueous layer, the organic layer was dried (Na2SO4) and concentrated to afford the title compound (3.49 kg, 100%) as an oil. Upon sitting at rt, the product crystallized. IR (KBr pellet): 3445, 3258, 3091.6, 2981.4, 2945.5, 1942.4, 1645.6, 1588.6, 1557.4, 1462.9, 1414.5, 1368, 1386.2,1262, 1209, 1130, 1112.5, 1071.8, 1030.9, 100.9, 893.8. MS (ES+): mass calculated for C9H9Cl2NO2, 233.00; m/z found 234.0 [M+H]+. Mp: 39.5-43.2° C. 1H NMR (400 MHz, CDCl3): 7.80 (d, J=2 Hz, 1H), 7.54 (dd, J=8.4, 2.0 Hz, 1H), 7.46 (d, J=8.3 Hz, 1H), 3.54 (s, 3H), 3.34 (s, 3H). 13C NMR (100 MHz, CDCl3): 167.2, 135.0, 133.9, 132.4, 130.7, 130.2, 127.9, 61.5, 33.7.
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