反应详情

To a 2000 ml round bottom flask was added (5S)-1-{[(1,1-dimethylethyl)oxy]carbonyl}-4,5-dihydro-1H-pyrazole-5-carboxylic acid (34 g, 159 mmol) in tetrahydrofuran (THF) (600 mL), followed by HCl (397 mL, 1587 mmol) (4 M in dioxane). The mixture was stirred at room temperature for 18 hours, and then ether (600 mL) was added. After stirring for 5 min, the mixture was allowed to stand for 10 min and then the organic solvents were decanted. The solid was collected by filtration and dried under high vacuum to provide (5S)-4,5-dihydro-1H-pyrazole-5-carboxylic acid, hydrochloride (22.4 g, 149 mmol, 94% yield) as a pale yellow solid. 1H NMR (400 MHz, METHANOL-d4): δ ppm 3.40-3.66 (m, 2H) 4.75-4.84 (m, 1H) 8.05-8.13 (m, 1H).

1. stirringAfter stirring for 5 min
2. waitto stand for 10 min
3. customthe organic solvents were decanted
4. filtrationThe solid was collected by filtration
5. customdried under high vacuum