To a solution of 5-[2-(p-toluenesulfonyloxy)ethyl]-7-chloro-1-[2-methyl-4-(2-methylbenzoylamino)benzoyl]-2,3,4,5-tetrahydro-1H-benzazepine (0.25 g) in dry dimethylformamide (20 ml) are added sodium iodide (0.178 g) and 4-acetylpiperazine (0.152 g), and the mixture is stirred at room temperature for one hour. The mixture is heated at 50° C. for 2 hours, and further at 60° C. for 3 hours. To the reaction solution are added 1N-hydrochloric acid and diethyl ether, and the aqueous layer is collected and neutralized with saturated aqueous sodium hydrogen carbonate solution, and extracted with dichloromethane. The dichloromethane layer is washed with water, dried, and the solvent is distilled off. To the resulting residue is added hydrochloric acid/ethanol to give 5-[2-(4-acetyl-1-piperazinyl)ethyl]-7-chloro-1-[2-methyl-4-(2-methylbenzoylamino)benzoyl]-2,3,4,5-tetrahydro-1H-benzazepine hydrochloride (150 mg) as colorless amorphous.
