GENERAL METHODS: A mixture of 2-amino-4,5-dimethylthiophene-3-carboxamide (1 mmol) and compound (CAS:77287-34-4) (1 mmol) with formamide (5-6 mmol) in acetic acid (1 mmol) was placed in a microwave reactor and irradiated for 10 min at 130 °C under 300 W power. After completion of the reaction, the reaction mixture was cooled to room temperature and subsequently poured into cold water. The precipitate was collected by filtration, washed with water and finally recrystallized from ethanol to obtain the pure product. The product 5,6-dimethyl-3H-thieno[2,3-d]pyrimidin-4-one (4a) had a melting point of 180-183 °C; IR (cm^-1 ): 3320 (NH), 1670 (C=O); 1H-NMR (DMSO-d6) δ: 1.7 (s, 3H, CH3), 2.0 (s, 3H, CH3), 7.80 (s, 1H Pyrimidine-H), 10.00 (br.s, 1H, NH); MS: m/z 180 [M+] (95) (C8H8N2OS); Elemental analysis of calculated values (%): C: 53.33, H: 4.44, N: 15.55; measured values (%): C: 53.45, H: 4.30, N: 15.56.
![5,6-DIMETHYLTHIENO[2,3-D]PYRIMIDIN-4(3H)-ONE Structure](/CAS/GIF/18593-44-7.gif)
![5,6-DIMETHYLTHIENO[2,3-D]PYRIMIDIN-4(3H)-ONE pictures](https://img.chemicalbook.com/ProductImageEN/2020-1/Small/8b78a974-c397-48f5-a9ca-43e57fda5311.png)