A solution of 2,3,5-trimethyl-1H-pyrrolo[2,3-d]-pyridazin-4(5H)-one (532 mg) in DMF (45 ml) was dripped into a suspension of 60% sodium hydride-oil (144 mg) in DMF (12 ml) on an ice-water bath. The mixture was stirred at room temperature for 30 minutes, after which a solution of 4-(4-chlorobenzoyl)benzyl bromide (1.02 g) in DMF (15 ml) was added and the mixture was further stirred at room temperature for 1.5 hours. The reaction was stopped by adding water and the reaction mixture was extracted with ethyl acetate. The extract was dried over anhydrous magnesium sulfate and the solvent was distilled off under reduced pressure. The residue was purified by silica gel column chromatography (developer; n-hexane: ethyl acetate=1:2) to provide the title compound as light-yellow powder (711 mg, yield 58%).
