反应详情

温度

0 °C

To a solution of ethyl 5-amino-1-phenyl-1H-pyrazole-4-carboxylate (10 g, 43 mmol) in DMF (100 mL) at 0° C. was slowly added sodium hydride (60% dispersion, 1.9 g, 47.6 mmol). After the evolution of gas had ceased, bromoethane (3.55 mL, 47.6 mmol) was added dropwise. The reaction was stirred at 0° C. for 2 hour, then gradually warmed to RT. Water was added to the reaction, resulting in the formation of a precipitate which was collected by filtration and used directly in the next step. The material thus obtained was dissolved in EtOH (50 mL) along with 3N NaOH (38 mL) and the solution was heated to reflux overnight. The reaction was cooled to 0° C. and the pH was slowly adjusted to between 3-4 using 1N HCl. The resulting white precipitate was collected by filtration and recrystallized from acetonitrile to afford 5-(ethylamino)-1-phenyl-1H-pyrazole-4-carboxylic acid (6.6 g, 28.6 mmol). The compound had an HPLC retention time=2.32 min. CHROMOLITH® SpeedROD 4.6×50 mm (4 min.); Solvent A=10% MeOH, 90% H2O, 0.2% H3PO4; Solvent B=90% MeOH, 10% H2O, 0.2% H3PO4. LC/MS M+1=232.3. 1H NMR (500 MHz, DMSO-d6) δ ppm 0.89 (t, J=7.2 Hz, 3H), 2.77 (m, 2H), 6.14 (br. s, 1H), 7.43 (m, 1H), 7.52 (m, 4H), 7.72 (s 1H).

1. customat 0° C.
2. temperaturegradually warmed to RT
3. customresulting in the formation of a precipitate which
4. filtrationwas collected by filtration
5. customThe material thus obtained
6. temperaturethe solution was heated
7. temperatureto reflux overnight
8. temperatureThe reaction was cooled to 0° C.
9. filtrationThe resulting white precipitate was collected by filtration
10. customrecrystallized from acetonitrile