58347-49-2

Pyrazolo[1,5-a]pyrimidin-7(4H)-one (0.50 g, 3.70 mmol) was added with phosphorus trichloride (0.88 mL, 9.62 mmol) and diisopropylethylamine (DIEA, 0.13 mL, 0.74 mmol), mixed well and then the reaction was stirred at 90 °C overnight. After completion of the reaction, the reaction mixture was slowly poured into ice water and extracted with dichloromethane, and the extract was washed with brine. The organic phase was dried over anhydrous sodium sulfate, filtered and concentrated in vacuum. The crude product was purified by silica gel column chromatography (eluent: hexane/ethyl acetate = 9:1) to afford the target compound 7-chloropyrazolo[1,5-a]pyrimidine (83 mg, 71% yield).LRMS (m/z): 154 (M + 1)+.1H NMR (400 MHz, DMSO-d6) δ ppm: 6.93 (d, 1H), 7.43 (d, 1H), 8.37 (d, 1H), 8.37 (d, 1H). 1H), 8.37 (d, 1H), 8.52 (d, 1H).

[1] Patent: EP2518071, 2012, A1. Location in patent: Page/Page column 38
[2] Patent: WO2012/146667, 2012, A1. Location in patent: Page/Page column 90
[3] Patent: WO2012/146666, 2012, A1. Location in patent: Page/Page column 160
[4] Patent: WO2007/17678, 2007, A1. Location in patent: Page/Page column 44
[5] Journal of Medicinal Chemistry, 1981, vol. 24, # 5, p. 610 - 613