反应详情

温度

60 °C

A mixture of 3-nitro-1H-pyrazole-5-carboxylic acid (4.71 g, 30 mmol), BH3/THF (75 mL, 1 mol/L, 75 mmol) was stirred at 60° C. for 2 h. The mixture was cooled to room temperature and 4M HCl (19 mL, 75 mmol) was added. It was stirred at 70° C. for 2 h. After cooling down to room temperature, the mixture was concentrated under reduced pressure. The residue was partitioned between ethyl acetate and brine (100:100 mL). The aqueous phase was extract with ethyl acetate (4×50 mL). The combined organic layer was dried on Na2SO4 and evaporated under reduced pressure. The residue was purified by silica-gel column chromatography eluting with petroleum ether/ethyl acetate (5:1 to 1:1) to afford 139a (3.5 g, 79%) as a white solid. MS-ESI: [M+H]+ 144.2

1. temperatureThe mixture was cooled to room temperature
2. stirringIt was stirred at 70° C. for 2 h
3. temperatureAfter cooling down to room temperature
4. concentrationthe mixture was concentrated under reduced pressure
5. customThe residue was partitioned between ethyl acetate and brine (100:100 mL)
6. extractionThe aqueous phase was extract with ethyl acetate (4×50 mL)
7. customThe combined organic layer was dried on Na2SO4
8. customevaporated under reduced pressure
9. customThe residue was purified by silica-gel column chromatography
10. washeluting with petroleum ether/ethyl acetate (5:1 to 1:1)