5-Hydroxypyrazolo[1,5-a]pyrimidine

1001-26-9

1225387-53-0

29274-22-4

The general procedure for the synthesis of pyrazolo[1,5-a]pyrimidin-5-ol from ethyl 3-ethoxyacrylate and 3H-pyrazol-3-amine was as follows: 5-aminopyrazole (5 g, 60 mmol), ethyl 3-ethoxyacrylate (13 g, 90 mmol) and cesium carbonate (29 g, 90 mmol) were mixed in 100 ml of N,N-dimethylformamide. The reaction mixture was stirred at 110 °C overnight. After the reaction was completed, it was cooled to room temperature, diluted with 200 ml of water and then extracted with ether (40 mL x 3). The aqueous phase was concentrated under reduced pressure and the residue was purified by silica gel column chromatography (eluent ratio of dichloromethane: methanol = 10:1) to afford 4H-pyrazolo[1,5-a]pyrimidin-5-one (8 g) in 99% yield.