反应详情

温度

40 °C

To a solution of ethyl 1-tert-butyl-5-methyl-1H-pyrazole-3-carboxylate (0.60 g, 2.85 mmol) in a mix of ethanol:water:dioxane (1:1:1, 9 mL) was added lithium hydroxide (0.48 mg, 11.4 mmol). The mixture was stirred at 40° C. for 5 hours. The solution was checked by LC-MS and diluted with water (10 mL) and the pH adjusted to 2 with 1N HCl. The solution was extracted with EtOAc (2×10 mL) and the combined organic phases washed with brine (20 mL), dried (NaSO4), and concentrated in vacuo to obtain 1-tert-butyl-5-methyl-1H-pyrazole-3-carboxylic acid (0.50 g, 96% yield). 1H NMR (400 MHz, DMSO-d6): δ 12.4 (s, 1H), 5.47 (s, 1H), 2.42 (s, 3H), 1.56 (s, 9H); MS (ESI) m/z: 183.1 (M+H+).

1. extractionThe solution was extracted with EtOAc (2×10 mL)
2. washthe combined organic phases washed with brine (20 mL)
3. dry with materialdried (NaSO4)
4. concentrationconcentrated in vacuo