A solution of 2-amino-5-(tetrahydro-furan-2-yl)-4-trifluoromethyl-benzoic acid methyl ester (2 g, 6.91 mmol) in anhydrous THF (30 mL) was treated with (CCl3O)2CO (684 mg, 2.28 mmol). The resultant yellow solution was stirred at r.t. for 15 min and Et3N (967 μL, 6.91 mmol) was then added. A thick suspension developed that was diluted with anhydrous THF (20 mL). The suspension was stirred for 3 h at r.t. CH3SO2NHNH2 (777 mg, 6.91 mmol) was added and the reaction was stirred for 1 h. The reaction mixture was then treated with aq NaOH (1 N, 14 mL, 14 mmol) and the resultant orange-red solution was stirred for 1 h at r.t. The reaction mixture was acidified to pH 3-4 with aq HCl (4 N) and extracted with EtOAc. The organic phase was dried (Na2SO4), filtered and concentrated in vacuo. The residue was taken into DCM and triturated. The colorless suspension was collected by vacuum filtration and further dried in vacuo at 60° C. to give the title product (2.36 g, 87%) as colorless crystals. m.p.: 254-257° C., API-ES: m/z 394 [M+H].
