221241-31-2

221241-25-4

221241-31-2

General procedure for the synthesis of 2,5-dibromo-4-nitropyridine as 2,5-dibromo-4-nitropyridine nitrogen oxide: 2,5-dibromo-4-nitropyridine nitrogen oxide (18 g, 60.84 mmol) was added batchwise to stirred phosphorus tribromide (46 mL) at 0-5 °C. The reaction mixture was kept stirred at 5 °C for about 7 hours. Upon completion of the reaction, the mixture was slowly poured onto crushed ice and extracted with ethyl acetate. The organic layers were combined, washed with saturated brine and dried over anhydrous sodium sulfate. Subsequently, the organic phase was concentrated under reduced pressure to give the crude product. Finally, the crude product was purified by fast column chromatography (petroleum ether: ethyl acetate = 10:1) to afford the target compound 2,5-dibromo-4-nitropyridine (10 g, 59% yield).