General procedure for the synthesis of 1-bromo-5-fluoro-2-nitrobenzene from 4-fluoroaniline: N-bromosuccinimide (34 g, 180 mmol) was dissolved in dichloromethane (60 mL) at 0 °C and slowly added dropwise to a solution of 4-fluoroaniline (20 g, 180 mmol) in dichloromethane (100 mL). The reaction mixture was stirred at room temperature overnight. Upon completion of the reaction, it was washed sequentially with saturated sodium sulfite solution, saturated sodium bicarbonate solution and brine, and then concentrated to give 1-bromo-5-fluoro-2-nitrobenzene (34 g, 154.5 mmol, 100% yield). The 1H NMR (400 MHz, CDCl3) data of the product were as follows: δ 7.12-7.21 (m, 1H), 7.47 (dd, J = 7.60, 2.40 Hz, 1H), (dd, J = 9.60, 6.40 Hz, 1H).
