General procedure for the synthesis of 4-bromo-5-chloro-2-fluoroaniline from 2-fluoro-5-chloroaniline: N-bromosuccinimide (1 eq.) was added to a solution of 5-chloro-2-fluoroaniline (1 eq.) in acetonitrile (0.5 M) at 25 °C. The reaction mixture was stirred at 25 °C for 1 hour. After completion of the reaction, the mixture was concentrated to dryness and the residue obtained was purified by silica gel column chromatography to afford 4-bromo-5-chloro-2-fluoroaniline in 91% yield as a yellow oil.1H NMR (400 MHz, CDCl3) δppm: 7.23 (d, J = 10.2 Hz, 1H), 6.88 (d, J = 8.4 Hz, 1H), 3.92- 2.64 (br, 2H).
