反应详情

To a stirred solution of methyl 1H-indazole-5-carboxylate (500 mg, 2.84 mmol) in MeOH (15 mL) is added sodium hydroxide (20 mL of 2.5% aqueous solution). The mixture is heated at reflux for 1 h, followed by removal of the methanol in vacuo. The remaining aqueous solution is washed with EtOAc (5 mL), acidified with 1 N aqueous HCl to pH˜5-6. The resulting precipitate is collected by filtration, washed with water and dried in vacuo to afford 410 mg (89%) of 1H-indazole-5-carboxylic acid as a tan solid: IR (diffuse reflectance) 3290, 3115, 2964, 2954, 2813, 2606, 2557, 2505, 1687, 1627, 1321, 1274, 948, 937, 769 cm−1; 1H NMR (400 MHz, DMSO-d6) δ 13.4 12.7, 8.5 8.2, 7.9, 7.6.

1. temperatureThe mixture is heated
2. temperatureat reflux for 1 h
3. customfollowed by removal of the methanol in vacuo
4. washThe remaining aqueous solution is washed with EtOAc (5 mL)
5. filtrationThe resulting precipitate is collected by filtration
6. washwashed with water
7. customdried in vacuo