反应详情

温度

110 °C

A mixture of 6-hydroxy-1H-pyrazolo[3,4-b]pyridine-4-carboxylic acid ethyl ester (116.4 g, 0.562 mol) and phosphorus oxychloride (500 mL) was heated at 110° C. for 6 hours then cooled to room temperature before being evaporated under reduced pressure. The residue was taken up in EtOAc and the precipitate filtered. The filtrate was neutralized using triethylamine (500 mL) and the resulting salt filtered. The filtrate was concentrated under vacuum and the residue subjected to silica gel column chromatography using a 9/1 mixture of toluene/EtOAc to afford the title compound as a yellow solid (26.3 g, 21%).

1. temperaturethen cooled to room temperature
2. custombefore being evaporated under reduced pressure
3. filtrationthe precipitate filtered
4. filtrationthe resulting salt filtered
5. concentrationThe filtrate was concentrated under vacuum
6. additiona 9/1 mixture of toluene/EtOAc