13345-09-0

26032-72-4

Step 2: Synthesis of 2,4-dichloro-6-phenylpyrimidine; in 50.0 ml of reaction system. To a round-bottomed flask equipped with a magnetic stirrer and a reflux condenser, protected by argon, 6-phenylpyrimidine-2,4(1H,3H)-dione (2.22 g, 11.8 mmol) and phosphorus trichloride (11.0 ml, 118 mmol) were added. The flask was placed in an oil bath preheated to 116 °C and rapidly heated to reflux. The reaction mixture was stirred at 116 °C for 4 h in an argon atmosphere and subsequently cooled to room temperature. The reaction progress was monitored by LC-MS (m/e 225 [M + H]+) to confirm product generation. Subsequently, a short-range distillation unit was installed to remove the excess phosphorus trichloride by decompression distillation at 116 °C. The residue was further distilled at ~70 °C to remove unreacted feedstock. The crude product was cooled to -3°C (using an ice bath and monitoring the temperature via a built-in thermometer). The reaction was quenched by the slow addition of ice water while keeping the temperature below 10°C. The reaction mixture was continued to be stirred in an ice bath for 60 minutes to induce precipitation of the product. The precipitate was collected by vacuum filtration and analyzed by LC-MS and confirmed to be the target product 2,4-dichloro-6-phenylpyrimidine (1.74 g, 7.7 mmol, 65% yield). m/e MS (ES) 225 [M + H]+.