A solution of 3-[4-({[4′-(2-ethoxyethoxy)-2′,6′-dimethylbiphenyl-3-yl]methyl}amino)-2-fluorophenyl]propanoic acid (0.251 g, 0.500 mmol), 7 M ammonia/methanol (0.4 mL, 2.80 mmol) solution, 1-ethyl-3-(3-aminopropyl)carbodiimide hydrochloride (288 g, 1.50 mmol), 1-hydroxybenzotriazole (0.230 g, 1.50 mmol), 1,8-diazabicyclo[5.4.0]-7-undecene (0.448 mL, 3.00 mmol) and triethylamine (0.502 mL, 3.60 mmol) in acetonitrile (3 mL) was stirred at room temperature for 24 hr. The reaction mixture was poured into saturated aqueous sodium hydrogencarbonate solution, and the mixture was extracted with ethyl acetate. The extract was washed with saturated brine, dried over anhydrous sodium sulfate, and concentrated under reduced pressure. The residue was purified by basic silica gel column chromatography (50% ethyl acetate/hexane-ethyl acetate) to give the title compound (0.206 g, yield 89%) as a colorless oil.
