反应详情

温度

-78 °C

To a −78° C. solution of 4-bromo-1-t-butyl-1H-pyrazole (15 g, 74.3 mmol) in anhydrous THF (100 mL) was added n-BuLi (2.5 M in hexane, 53 mL, 132 mmol) under N2, and the resulting mixture was stirred at −78° C. for 30 min. Excess dry ice was added at −78° C., and the mixture was warmed slowly to RT and stirred overnight. The reaction was concentrated in vacuo, water was added and the pH was adjusted to pH 3 by the addition of 2N aq HCl. The aqueous solution was extracted with EtOAc. The extracts were washed with brine, dried (MgSO4) and concentrated in vacuo. The residue was recrystallized (EtOAc-pet. ether) to give 1-t-butyl-1H-pyrazole-4-carboxylic acid (8.0 g, 67% yield). 1H NMR (300 MHz, CDCl3): δ 8.10 (s, 1 H), 8.03 (s, 1 H), 1.64 (s, 9 H); MS (ESI) m/z: 168.9 [M+H]+.

1. temperaturethe mixture was warmed slowly to RT
2. stirringstirred overnight
3. concentrationThe reaction was concentrated in vacuo, water
4. additionwas added
5. additionthe pH was adjusted to pH 3 by the addition of 2N aq HCl
6. extractionThe aqueous solution was extracted with EtOAc
7. washThe extracts were washed with brine
8. dry with materialdried (MgSO4)
9. concentrationconcentrated in vacuo
10. customThe residue was recrystallized (EtOAc-pet. ether)