Two grams of 6,7-dimethoxy-1,2,3,4-tetrahydroquinazoline-2,4-dione was dissolved in 30 ml of dimethylformamide. After adding 1230 mg of sodium hydride thereto under cooling, the mixture was stirred for 10 minutes. Then, 23 grams of 2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl chloride was added and the stirring was continued at 70° C. for 6 hours. After the reaction was finished, water was added to the reaction mixture and the mixture was extracted with chloroform and concentrated. The resultant residue was purified through the silica gel chromatography and crystallized from methanol to obtain 1.4 g of the titled compound (yield: 35%).
