Method F1: Synthesis of 2,4-dichloro-6-methoxyquinazoline (xa)
To a mixture of 6-methoxyquinazoline-2,4(1H,3H)-dione (9.63 g, 50.2 mmol) and phosphorus trichloride (POCl3, 150 mL) was added N,N-dimethylaniline (0.5 mL). The reaction mixture was stirred at 120 °C for 2 hours. Upon completion of the reaction, the excess POCl3 was removed by distillation under reduced pressure. the residue was slowly poured into ice water and the pH was adjusted to about 7 by slowly adding saturated sodium bicarbonate (NaHCO3) solution at 0 °C, where a precipitate was formed. The precipitate was collected and dried under vacuum to give 2,4-dichloro-6-methoxyquinazoline (11.2 g, 98% yield) as a brown solid.
LCMS m/z = 229.1, 231.0 [M + 1] (Method B) (retention time = 1.87 min).
1H-NMR (400 MHz, DMSO-d6): δ 7.89 (d, J = 9.2 Hz, 1H), 7.71 (dd, J = 8.8, 2.4 Hz, 1H), 7.38 (d, J = 1.6 Hz, 1H), 3.91 (s, 3H).
