反应详情

1-Ethyl-4-hydroxy-1H-pyrazolo[3,4-b]pyridine-5-carboxylic acid, ethyl ester (15 g, 63.8 mmol) was dissolved in phosphorus oxychloride (100 mL), and the resulting solution was heated at reflux for 4 h. The remaining phosphorus oxychloride was removed via evaporation under reduced pressure. The residual light brown solid was recrystallized from EtOH-hexane to afford the title compound as a white solid (14 g, 55.3 mmol, 87%): HPLC (YMC S5 ODS 4.6×50 mm column, 4 minute gradient-0% B to 100% B, 4 mL/min flow, solvent A: 10% MeOH-90% H2O-0.2% H3PO4, solvent B: 90% MeOH-10% H2O-0.2% H3PO4) retention time 3.84 minutes showed a purity of 96%; LRMS (m/z) 254 (MH+).

1. temperaturethe resulting solution was heated
2. temperatureat reflux for 4 h
3. customThe remaining phosphorus oxychloride was removed via evaporation under reduced pressure
4. customThe residual light brown solid was recrystallized from EtOH-hexane