6-Methylquinazoline-2,4(1H,3H)-dione (550 mg, 3.12 mmol) was used as a starting material, which was dissolved in POCl3 (4.0 mL), followed by the addition of N,N'-diethylaniline (0.5 mL). The reaction mixture was heated to 135 °C and the reaction was stirred at this temperature for 3 hours. Upon completion of the reaction, the mixture was cooled to room temperature and carefully poured into ice water. The precipitated solid was collected by filtration and dried to afford 2,4-dichloro-6-methylquinazoline (590 mg, 89% yield), which could be used in subsequent steps without further purification.
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