General procedure for the synthesis of 5-bromo-2-nitro-N-phenyl-aniline from 2-fluoro-4-bromonitrobenzene and aniline: 4-bromo-2-fluoronitrobenzene (5.6 g, 20.9 mmol) and aniline (2.5 g, 72.2 mmol) were dissolved in 50 mL of anhydrous N-methylpyrrolidone (NMP). The reaction mixture was heated to 110 °C and the reaction was stirred overnight. After completion of the reaction, it was cooled to room temperature and the solvent was removed by distillation under reduced pressure. The crude product was purified by silica gel column chromatography with the eluent cyclohexane/ethyl acetate (9:1, v/v) to give an orange solid product in 92% yield (5.7 g). The 1H-NMR (400 MHz, CD2Cl2) data of the product were as follows: δ= 9.48 (s, 1H), 8.06 (d, 1H), 7.46 (t, 2H), 7.30 (t, 4H), 6.89 (d, 1H).
