57489-77-7

57489-70-0

57489-77-7

The general procedure for the synthesis of 5,7-dichloropyrazolo[1,5-a]pyrimidines from 7-hydroxy[1,5-a]pyrimidin-5(4H)-ones was as follows: trichlorophosphorus oxychloride (POCl3, 130 mL) was added to a reaction vial containing pyrazolo[1,5-a]pyrimidine-5,7-diol (10 g, 66 mmol). After the resulting suspension was cooled to 0°C, N,N-dimethylaniline (23 mL, 179 mmol) was slowly added. After the reaction mixture was warmed up to room temperature, the reaction was heated at 60°C for 16 h under the protection of nitrogen (N2). After completion of the reaction, the mixture was cooled to room temperature and concentrated to give a brown viscous liquid. This liquid was slowly poured into ice water and allowed to gradually warm to room temperature. Subsequently, the pH of the mixture was adjusted with saturated sodium bicarbonate (NaHCO3) solution to 8. The organic layer was extracted with dichloromethane (CH2Cl2, 4 x 50 mL), and the organic phases were combined and dried over anhydrous magnesium sulfate (MgSO4). The dried organic phase was concentrated under reduced pressure to give a brown liquid. Finally, the target product, 5,7-dichloropyrazolo[1,5-a]pyrimidine (10.7 g, 86% yield), was obtained as a white crystalline solid by fast column chromatography with the eluent ratio varied from 1:1 (v/v) dichloromethane:hexane gradient to 2:1 (v/v) dichloromethane:hexane. Mass spectrometry (MS) analysis showed m/z 189.36 [M + 1].