1224288-92-9

1224288-95-2

1224288-92-9

General procedure for the synthesis of 5-chloropyrazolo[1,5-a]pyrimidine-3-carbonitrile from 5-oxo-4,5-dihydropyrazolo[1,5-a]pyrimidine-3-carbonitrile: 5-hydroxypyrazolo[1,5-a]pyrimidine-3-carbonitrile (10.00 g, 62.45 mmol) was mixed with phosphorus triclosamide (200.00 mL), heated to 150 °C, and the reaction took 4 hour. The progress of the reaction was monitored by thin layer chromatography (TLC, unfolding agent ratio petroleum ether: ethyl acetate = 1:1). Upon completion of the reaction, the excess of phosphorous trichloride was removed by distillation under reduced pressure, and the residue was dissolved in dichloromethane and concentrated again. Finally, it was purified by silica gel column chromatography (eluent was dichloromethane) to afford 5-chloropyrazolo[1,5-a]pyrimidine-3-carbonitrile (6.00 g, yield 53.80%) as a white solid.