To a mixture of 4-chloro-6-oxo-1-phenyl-1,6-dihydropyridazine-3-carboxylic acid methyl ester (0.250 g, 0.944 mmol) in 1,2-dichlorobenzene (3.8 mL) was added 4-bromo-2-fluoro aniline (0.561 g, 3.78 mmol), and cesium carbonate (0.615 mg, 1.89 mmol). The reaction mixture was heated to reflux. After 1 hour, the reaction mixture was cooled to room temperature. Water was added and the mixture was diluted with EtOAc. The aqueous layer was separated, acidified with 10% HCl solution, and extracted with EtOAc. The combined organic layers were dried (MgSO4), concentrated under reduced pressure, and triturated to give 0.153 g (43%) of the desired product.
