A mixture of 5-bromo-2-(2-chlorophenylamino)-3,4-difluorobenzoic acid methyl ester (2.07 g, 5.50 mmol), NCS (789 mg, 5.91 mmol), and catalytic amount of conc. HCl in DMF (41 mL) was stirred for 1 hour at room temperature. The reaction mixture was diluted with EtOAc, and washed with water (5×). The organic layer was dried over MgSO4, filtered, and concentrated to give the crude material which was purified by silica gel flash column chromatography (3 to 5% EtOAc in hexanes) to afford the desired product (2.02 g, 89%).
