In a 10 mL pressure-resistant stainless steel reactor, 1.00 g (7.2 mmol) of 2-aminonicotinic acid, 3.07 g (28.8 mmol) of trimethyl orthoformate and 5.0 mL (38 mmol) of 15 wt% ammonia-methanol solution were added and the reaction was carried out for 8 hr at 105 °C. After completion of the reaction, the reaction mixture was cooled to room temperature and concentrated under reduced pressure to afford 1.06 g (Yield: 100%) of 3H-pyrido[2,3-d]pyrimidin-4-one as a black solid. The product was characterized by the following data: 1H-NMR (DMSO-d6, δ/ppm): 3.36 (1H, brs), 7.46 (1H, dd, J = 8.0, 4.5 Hz), 8.31 (1H, s), 8.45 (1H, dd, J = 7.8, 2.1 Hz), 8.87 (1H, dd, J = 4.8, 2.1 Hz); CI- MS (m/e): 148 (M+1).
![PYRIDO[2,3-D]PYRIMIDIN-4(1H)-ONE](/CAS/GIF/24410-19-3.gif)