A mixture of 4-[4-(2-tert-butylphenyl)piperazin-1-yl]-4-oxobutanoic acid obtained in Example 53 (500 mg), N-(cyclopropylmethyl)sulfamide (248 mg), 2-methyl-6-nitrobenzoic anhydride (692 mg), N,N-dimethylaminopyridine (192 mg), triethylamine (0.656 mL), and acetonitrile (10 mL) was stirred at room temperature for over-night. Water was added to the reaction solution, and the mixture was extracted with ethyl acetate. The ethyl acetate layer was washed with saturated brine, and dried over anhydrous magnesium sulfate. The solvent was evaporated under reduced pressure to provide the title compound (148 mg, 21%) as a colorless solid.
