14080-50-3

14080-59-2

General procedure for the synthesis of 4-chlorothieno[2,3-d]pyrimidine using thieno[2,3-d]pyrimidin-4(3H)-one as starting material: a solution of N,N-dimethylformamide (DMF, 1.53 mL, 19.7 mmol) in dichloromethane (50 mL) was cooled to 0 °C, oxalyl chloride (2.5 mL, 29.6 mmol) was slowly added, and the reaction system formed a A white gel-like substance was formed in the reaction system. Thieno[2,3-d]pyrimidin-4(3H)-one (1.5 g, 9.86 mmol) was then added and the reaction mixture was heated to reflux for 3 hours. After completion of the reaction, the mixture was cooled to room temperature and poured into water. The aqueous phase was extracted with dichloromethane, the organic phases were combined and dried over anhydrous sodium sulfate and subsequently concentrated under reduced pressure. The crude product was purified by silica gel column chromatography (eluent: ethyl acetate/hexane=15:1) to afford 4-chlorothieno[2,3-d]pyrimidine as a white solid (1.61 g, 96% yield). The structure of the product was confirmed by 1H NMR (300 MHz, CDCl3, 25 °C): δ= 8.88 (s, 1H, CH), 7.64 (d, J = 6.0 Hz, 1H, CH), 7.47 (d, J = 5.8 Hz, 1H, CH) ppm. high-resolution mass spectrometry (HRMS) analysis showed that the calculated value C6H4ClN2S [M]+ 170.97837, measured value 170.97804.