To a stirred solution of methyl (1R,2S)-2-[(4-fluoro-3-methylbenzyl)amino]cyclopentanecarboxylate (120 mg, 0.45 mmol) and (7-methanesulfonylamino-1,1-dioxo-1,4-dihydro-1λ6-benzo[1,2,4]thiadiazin-3-yl)-acetic acid (prepared as described in Example 1j, 150 mg, 0.45 mmol) in anhydrous N,N-dimethylformamide (4 mL) under a nitrogen atmosphere, N-methylmorpholine (0.15 mL, 1.40 mmol) and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (86 mg, 0.45 mmol) were added sequentially. The mixture was stirred at 25° C. for 2.5 h, and then poured into 1.0 M aqueous hydrochloric acid solution and extracted with ethyl acetate. The combined organic layers were washed with saturated aqueous brine solution, dried over magnesium sulfate and filtered. The filtrate was concentrated in vacuo to afford the amide intermediate, which was used directly in the next step without further purification.
