1-[3-(dimethylamino)propyl]-3-ethylcarbodiimide hydrochloride (62 mg), 1-hydroxybenzotriazole (43 mg), ammonium chloride (43 mg) and TEA (0.038 ml) were added to a DMF (3.0 ml) solution of 5-[({4-[2-(3-cyanophenyl)ethyl]-1-piperidyl}carbonyl)oxy]nicotinic acid (102 mg), followed by stirring overnight at room temperature. An aqueous saturated sodium hydrogencarbonate solution was added to the reaction liquid, and the crystal precipitated was collected by filtration and dried. The resulting crystal was recrystallized from EtOAc/hexane to give 5-(aminocarbonyl)-3-pyridyl 4-[2-(3-cyanophenyl)ethyl]-1-piperidinecarboxylate (81 mg).
