To a mixture of 4-{[1-(5-chloro-1-methyl-1H-indol-2-yl)heptyl]amino}benzoic acid (300 mg) synthesized in Example A140(3), ethyl 3-(methylamino)propanoate (148 mg), 1-hydroxybenzotriazole monohydrate (173 mg), triethylamine (158 μL) and N,N-dimethylformamide (10 mL) was added 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (217 mg), and the mixture was stirred overnight at room temperature. Saturated aqueous ammonium chloride solution was added to quench the reaction, and the reaction mixture was extracted with ethyl acetate. The extract was washed with saturated aqueous sodium hydrogen carbonate solution and saturated brine, dried over magnesium sulfate, and concentrated under reduced pressure. The residue was purified by silica gel column chromatography (30-70% ethyl acetate/hexane) to give the title object compound (235 mg, 61%) as a pale-yellow oil.
