Synthesis
General procedure for the synthesis of 2,5-dibromo-3-chloropyridine from 5-bromo-2,3-dichloropyridine: To 5-bromo-2,3-dichloropyridine (11.7 g, 51.6 mmol) was added 5 M hydrobromic acid solution of acetic acid (51.6 mL, 258 mmol) at room temperature. The reaction mixture was then heated to 70 °C and kept stirring for 7 hours. Upon completion of the reaction, the reaction mixture was diluted with ethyl acetate, the reaction was quenched with water and extracted with ethyl acetate. The organic layers were combined, washed with 1 M sodium hydroxide solution, dried over anhydrous sodium sulfate and subsequently concentrated under reduced pressure. The residue was recrystallized by hexane-ethyl acetate mixed solvent to give 11.2 g of the target product 2,5-dibromo-3-chloropyridine in 80% yield as a white solid.1H-NMR (DMSO-d6) δ: 8.55 (1H, s), 8.49 (1H, s).
