243 mg (0.65 mmol) of ethyl [(2-amino-6-methoxybenzyl)-(4-chlorobenzoyl)amino]acetate was dissolved in 5 ml of dichloromethane. 156 mg (0.78 mmol) of 4-(2,5-dihydro-1H-pyrrol-1-ylcarbonyl)-benzaldehyde and 0.074 ml (1.3 mmol) of acetic acid were added to the obtained solution, and they were stirred at room temperature for 30 minutes. 340 mg (1.6 mmol) of sodium triacetoxyborohydride was added to the reaction mixture, and they were stirred at room temperature overnight. After the treatment with dichloromethane as the extracting solvent by an ordinary method, the obtained crude product was dissolved in a mixture of 2 ml of 1 N sodium hydroxide and 10 ml of ethanol, and the obtained solution was stirred at room temperature for 5 hours. After the treatment with ethyl acetate as the extracting solvent by an ordinary method, the obtained crude product was dissolved in 5 ml of dichloromethane. 131 mg (0.78 mmol) of 2-chloro-1,3-dimethyl-imidazonium chloride and 0.19 ml (1.3 mmol) of triethylamine were added to the obtained solution, and they were stirred overnight. The solvent was evaporated, and the obtained crude product was treated in the same manner as in step 3 in Example 1 to obtain the title compound.
