1-Benzyl-3-chloro-5-methoxypyridazin-4(1H)-one (13.6 g), 1-phenyl-5-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-1H-pyrazole (22.0 g), potassium carbonate (51.0 g) and bis(di-tert-butyl(4-dimethylaminophenyl)phosphine)dichloropalladium(II) (1.92 g) were suspended in toluene (330 mL) and water (33.0 mL), and the mixture was heated under reflux for 24 hr under a nitrogen atmosphere. The reaction mixture was cooled to room temperature, diluted with water and saturated aqueous sodium hydrogen carbonate solution, extracted with ethyl acetate, dried over anhydrous sodium sulfate, filtered, concentrated, and recrystallized from ethyl acetate/hexane to give the title compound (15.1 g).
