A solution of 2,3-dichloro-5-methyl-1H-pyrrolo [2,3-d]pyridazin-4(5H)-one (303 mg) in DMF (50 ml) was dripped into a suspension of 60% sodium hydride-oil (72 mg) in DMF (10 ml) on an ice-water bath. The mixture was stirred at room temperature for 2.5 hours, after which a solution of 3-(4-chlorobenzoyl) benzyl bromide (511 mg) in DMF (10 ml) was added and the mixture was further stirred at room temperature for 17 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=1:1) to provide the title compound as white powder (104 mg, yield 16%).
