General procedure for the synthesis of 2-amino-5-fluorobenzoic acid from 2-nitro-5-fluorobenzoic acid: 2-nitro-5-fluorobenzoic acid (10 g, 54 mmol) was dissolved in ethanol (100 mL) and 10% Pd/C catalyst (0.5 g) was added. The reaction was stirred at room temperature for 4 h under hydrogen atmosphere. Upon completion of the reaction, the catalyst was removed by diatomaceous earth filtration. The filtrate was concentrated under reduced pressure to give 8.2 g (98% yield) of the white solid product 2-amino-5-fluorobenzoic acid. Product melting point: 142 °C. 1H NMR (DMSO-d6) δ: 6.71 (dd, J = 4.9, 8.9 Hz, 1H), 7.15 (dt, J = 2.9, 8.4 Hz, 1H), 7.37 (dd, J = 2.9, 9.8 Hz, 1H), 8.60 (s, 1H).EIMS m/z 156 (M + 1).
