General procedure for the synthesis of 2-amino-3-bromo-5-fluorobenzoic acid from 2-amino-5-fluorobenzoic acid: N-bromosuccinimide (631 mg, 3.55 mmol) was added in batches to a stirred solution of 2-amino-5-fluorobenzoic acid (7,500 mg, 3.22 mmol) dissolved in acetic acid (5 mL) and the reaction mixture was stirred at room temperature overnight . The resulting precipitate was collected by filtration, washed with petroleum ether (20 mL) and dried to constant weight to afford 2-amino-3-bromo-5-fluorobenzoic acid (11,501 mg, 66.4% yield) as a clear beige solid. The product was used without further purification. The product characterization data were as follows: LCMS (t R = 1.35 min, purity = 100%), no ions detected at ESI m/z; 1H NMR (DMSO-d6) δ (ppm) 6.76 (broad single peak, 2H), 7.55 (double peak, J = 3.0 Hz, JH-F = 9.4 Hz, 1H), 7.71 (double peak, J = 3.0 Hz, JH F = 7.8 Hz, 1H), 12.72 (broad single peak, 1H); 13C NMR (DMSO-d6) δ (ppm) 109.4 (double peak, JC-F = 7.1 Hz), 111.1 (double peak, JC-F = 7.1 Hz), 116.2 (double peak, JC-F = 22.1 Hz), 124.9 (double peak, JC-F = 24.8 Hz), 145.1, 151.4 (double peaks, JC-F = 235.3 Hz), 168.1 (double peaks, JC-F = 2.7 Hz).
