o-Chlorophenylacetic acid → Acetyl chloride, 2-(2-chlorophenyl)-

15 ml of thionyl chloride was added to 0.44 g of 2-chlorophenylacetic acid. The mixture was stirred at room temperature for 2 hours. The reaction mixture was subjected to distillation to remove the remaining thionyl chloride and then to azeotropy with toluene twice to completely remove the thionyl chloride. The residue was dissolved in 10 ml of dichloromethane. 0.36 ml of triethylamine was added, with ice-cooling, to a dichloromethane solution containing 0.40 g of 5-dimethylamino-1-(4-aminobenzoyl)-2,3,4,5-tetrahydro-1H-benzoazepine. Thereto was dropwise added the above obtained 2-(2-chlorophenyl)acetyl chloride solution. The resulting mixture was stirred at room temperature for 1 hour. The reaction mixture was water-washed twice, then dried over magnesium sulfate and concentrated. The residue was purified by silica gel column chromatography (elutant: chloroform/methanol=200/1) and then recrystallized from methanol-diethyl ether to obtain 0.29 g of 5-dimethylamino-1-{4-[2-(2-chlorophenyl)acetylamino]benzoyl}-2,3,4,5-tetrahydro-1H-benzoazepine.