To a solution of 2-(methoxycarbonyl)-3-[4-[2-(2-naphthoxy)ethoxy]phenyl]propionic acid (2.08 g, 5.29 mmol) in benzene (20 ml) at room temperature is added thionyl chloride (0.76 g, 6.34 mmol). Then the mixture was heated at 80° C. for 90 min. After cooled to room temperature, the solvent is removed under a vacuum. To the residue is added 28% ammonia solution (5.49 ml, 79.30 mmol) at room temperature. The mixture is stirred for 30 min, dissolved in ethyl acetate (20 ml), washed with brine (3×15 ml), dried over sodium sulfate, and concentrated. The crude product is crystallized from ethanol to give title compound (0.98 g, 47%). HRMS calcd for C23H23NO5: 393.4364. Found: 393.4363. MA calcd for C23H23NO5: C, 70.22%; H, 5.89%; N, 3.56%. Found: C, 70.54%; H, 5.87%; N, 3.54%.
