GENERAL STEPS: 7-methylthieno[3,2-d]pyrimidine-2,4(1H,3H)-dione (89.4 g) was added to a solution of acetonitrile (450 mL) containing phosphorochloridic acid (312 g, 2.04 mol), and N,N-dimethylaniline (44.6 g, 0.368 mol) over 10 minutes. The reaction mixture was heated to 85°C and stirred at this temperature for 24 hours. Upon completion of the reaction, the mixture was cooled to room temperature and then slowly poured into a mixture of ice (900 g) and water (300 mL) while controlling the temperature below 10°C. Stirring was continued at this temperature for 30 minutes. The resulting solid product was collected by filtration, washed with water (450 mL) and subsequently dried under reduced pressure at 50 °C for 24 h to afford the target compound 2,4-dichloro-7-methylthieno[3,2-d]pyrimidine (97.0 g, 90% yield). The product was a white solid and its structure was confirmed by 1H NMR (400 MHz, CDCl3) δ 7.75 (s, 1H), 2.50 (s, 3H) and LCMS (ESI pos) m/z [M+H] 220.
![7-Methylthieno[3,2-d]pyrimidine-2,4-diol](/CAS/GIF/35265-81-7.gif)
![2,4-Dichloro-7-methylthieno[3,2-d]pyrimidine](/CAS/GIF/35265-83-9.gif)