[CH3:1][N:2]([CH3:9])[C:3](=[O:8])[C:4](Cl)=[N:5][OH:6].[F:10][C:11]1[CH:18]=[CH:17][CH:16]=[C:15]([F:19])[C:12]=1[CH:13]=[CH2:14].C(=O)(O)[O-].[K+]>ClC1C=CC=CC=1.O>[F:10][C:11]1[CH:18]=[CH:17][CH:16]=[C:15]([F:19])[C:12]=1[CH:13]1[O:6][N:5]=[C:4]([C:3]([N:2]([CH3:9])[CH3:1])=[O:8])[CH2:14]1To a 1 L round bottom flask equipped with a mechanical stirrer, thermometer and addition funnel was added 2-(dimethylamino)-N-hydroxy-2-oxoethanimidoyl chloride (94.0 g, 0.62 mol) and 2,6-difluorostyrene (84.0 g, 0.60 mol) in chlorobenzene (275 g). The reaction mixture was cooled to 10° C., and then potassium bicarbonate (70 g, 0.70 mol) in water (350 mL) was added dropwise over 1 h while maintaining the temperature between 10 and 15° C. When gas chromatography analysis of the reaction mixture showed about 3% of 2-(dimethylamino)-N-hydroxy-2-oxo-ethanimidoyl chloride remaining, water (200 mL) was added to the reaction mixture and the layers were separated. The organic layer was washed with water (300 mL) and concentrated under reduced pressure. Toluene was added to the resulting residue and the mixture was concentrated under reduced pressure to provide the title compound as an oil (144 g).
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