A mixture of 5-[3,6-dihydro-3-methyl-2,6-dioxo-4-(trifluoromethyl)-1(2H)-pyrimidinyl]-1,2-benzisothiazole-3-acetic acid (0.960 g, 0.00250 mol) and 1,1'-carbonyldiimidazole (0.420 g, 0.00259 mol) in tetrahydrofuran is stirred at room temperature for 4.5 hours, treated with ammonium chloride (0.230 g, 0.00430 mol), stirred overnight at room temperature, treated with concentrated ammonia (1.00 mL), stirred for 5 minutes, acidified with 10% hydrochloric acid, and concentrated in vacuo to obtain a residue. The residue is diluted with a 5% methanol in methylene chloride solution and the resultant mixture is stirred for three hours and filtered to obtain a solid. The solid is washed with a 5% methanol in methylene chloride solution, slurried in water, filtered, and dried to give the title product as a white solid which is identified by NMR spectral analysis.
