Dimethylformamide → Quinoline-6-carbonyl chloride

Quinoline-6-carboxylic acid (1.4 g) was dissolved in dichloromethane (50 ml). N,N-dimethylformamide (100 μL) and oxalyl chloride (1.6 g) were added to this solution at room temperature and stirred for two hours followed by reflux for 20 minutes. The solvent was removed by distillation under the reduced pressure to obtain crude quinoline-6-carbonyl chloride. It was dissolved in pyridine and added to 2-bromo-4-(1-bromo-1,1,2,3,3,3-hexafluoropropan-2-yl)-6-(difluoromethoxy)aniline (0.73 g) also dissolved in pyridine, and the resulting mixture was heated under reflux for 5 hours. After cooling to room temperature, the reaction solution was diluted with 1 N hydrochloric acid and extracted twice with ethyl acetate. The solvent was removed by distillation under the reduced pressure. The resulting residues were dissolved in tetrahydrofiaran (30 ml), added with 1 M aqueous solution of lithium hydroxide (50 ml), and stirred at room temperature for 2 hours. The reaction solution was extracted twice with ethyl acetate. The organic phases were combined, washed with water, and dried over anhydrous magnesium sulfate. The drying agent (anhydrous magnesium sulfate) was removed by filtration and the solvent was distilled off under the reduced pressure. The resulting residues were purified by column chromatography to obtain N-[2-bromo-4-(1-bromo-1,1,2,3,3,3-hexafluoropropan-2-yl)-6-(difluoromethoxy)phenyl]quinoline-6-carboxamide (0.84 g, 86%).