To a mixture of 4-{[(5-methoxy-3-methyl-1-benzofuran-2-yl)(phenyl)methyl]amino}benzoic acid (400 mg) synthesized above, ethyl 3-(methylamino)propanoate (203 mg), 1-hydroxybenzotriazole monohydrate (237 mg), triethylamine (431 μL) and N,N-dimethylformamide (10 mL) was added 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (297 mg), and the mixture was stirred overnight at room temperature. Water was added to quench the reaction, and the 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 (486 mg, 94%) as a pale-brown oil
