a) General procedure for the synthesis of 5-fluoro-2-nitrobenzoic acid: 3-fluorobenzoic acid (7.9 g, 56 mmol) was dissolved in concentrated sulfuric acid (50 mL), and the solution was cooled to 0 °C. Fuming nitric acid (4.7 g, 67 mmol) was added dropwise with stirring. After the dropwise addition, the reaction mixture was slowly warmed to room temperature and stirring was continued for 1 hour. Upon completion of the reaction, the mixture was carefully poured into water (750 mL) and extracted with ethyl acetate (3 x 100 mL). The organic phases were combined, dried with anhydrous magnesium sulfate, filtered and concentrated under reduced pressure to give 5-fluoro-2-nitrobenzoic acid as a light yellow solid (9.6 g, 52 mmol, 93% yield).1H NMR (300 MHz, d6-DMSO) data for 5-fluoro-2-nitrobenzoic acid: δ 7.66 (m, 1H), 7.74 (m, 1H), 8.17 (m, 1H) ppm.
