To a solution of (2-{3-[4-(4-fluoro-benzyl)-(2R,5S)-2,5-dimethyl-piperazin-1-yl]-3-oxo-propyl}-5-methyl-phenoxy)-acetic acid (0.052 g, 0.12 mmol) in methylene chloride (1 mL) was added 4-dimethylaminopyridine (0.022 g, 0.18 mmol), (3-(dimethylamino)propyl)ethyl carbodiimide hydrochloride (0.032 g, 0.17 mmol), methanesulfonamide (0.015 g, 0.16 mmol) and triethylamine (0.035 mL, 0.25 mmol). The reaction was stirred at ambient temperature for 18 hours. The reaction mixture was then diluted with dichloromethane and washed with 0.2 M aqueous hydrochloric acid. The organic layer was dried over magnesium sulfate and concentrated in vacuo. The crude product was purified by trituration in methylene chloride/diethyl ether/hexanes to give the title compound (0.050 g, LRMS: 520.3).
