(E)-8-(3-(1H-imidazol-1-yl)propylamino)-7-((naphthalen-1-yloxy)-methyl)-8-oxo-6-octenoic acid (286 mg, 0.65 mM) obtained in Example (2-1-2) was dissolved in dimethylformamide (3 ml), and triethylamine (136 μl, 0.98 mM) was added thereto. Then, the resulting mixture was cooled to 0° C., and to the mixture, N-hydroxy-6-trifluorobenzotriazole (144 mg, 0.72 mM), 1-(3-diethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC.HCl) (162 mg, 0.85 mM) and tetrahydropyranyloxyamine (114 mg, 0.98 mM) were added and stirred at room temperature for 18 hrs. After the completion of reaction, ice water was added to the reaction mixture. The resulting mixture was extracted with ethyl acetate. The organic layer was separated, washed with an aqueous saturated sodium bicarbonate solution and brine in order, dried over anhydrous magnesium sulfate, and concentrated under reduced pressure. The residue thus obtained was subjected to a silica gel column chromatography to obtain 220 mg of the title compound (yield 63%).
