89717-64-6

26621-44-3

89717-64-6

General procedure for the synthesis of 4-bromo-3-nitropyrazole from 3-nitro-1H-pyrazole: Water (15 mL) was added to a mixed system containing 3-nitro-1H-pyrazole (48a) (1 g, 8.90 mmol) and N-bromosuccinimide (NBS) (1.73 g, 9.70 mmol) at room temperature and the reaction mixture was stirred continuously overnight. The progress of the reaction was monitored by thin-layer chromatography (TLC) and after confirming that the reaction was complete, the reaction solution was diluted with water and subsequently extracted with ethyl acetate. The organic phase was sequentially washed with saturated sodium chloride solution, dried over anhydrous sodium sulfate, concentrated under reduced pressure, and the solvent was removed by rotary evaporation to afford the target compound 4-bromo-3-nitropyrazole (48b) (1.66 g, 93% yield, white solid). Mass spectrometry (ESI) data: m/z 192 [M + H]+.