7-Bromo-6-chloro-4-quinazolinone

Yellow-Brown Solid

To a mixture of 3-chlorotoluene (200 g, 1.58 mol), FeCl3 (9.4 g, 0.06 mol) and CH2Cl2 (1000 mL)stirred at 0~10 °C, Br2 (500 g, 3.12 mol) was added slowly, during which the produced gas wasabsorbed by 15percent NaOH aqueous solution (2000 mL). After 1 h of continued vigorous stirring, water(100 mL) was added and the mixture was adjusted to pH 8.0~10.0 with 10percent aqueous NaOH (200 mL).The organic layer was separated and concentrated to dryness under vacuum to give a solid (95.7percent, m.p.95~96 °C), 426 g of which was added to a mixture of water (2000 mL), pyridine (200 mL) and KOH(112 g, 2.0 mol) and heated. When the interior temperature reached 80 °C, KMnO4 (800 g, 5.0 mol) wasadded in portions, and the mixture was refluxed until complete consumption of the KMnO4. Then thesolution was filtered, the precipitate was washed with 10percent KOH a.q. (1000 mL). The filtrates werecombined, and then vacuum evaporated to remove the pyridine and form a turbid solution, whichneeded to be filtered again. The fresh filtrate was acidified with concentrated HCl (360 mL) to pH 3~4.Then the precipitate was filtered, dried and crushed (80percent, m.p. 170~171 °C). A portion (340 g) wasdissolved in 25percent NH3-H2O (1700 mL). To the solution, Cu2O was added in batches at 30~40 °C. Afterabout 5 h of stirring, the solution without NH3 gas was diluted and acidified. Then the solid was filtered, washed, dried (yield 96percent, m.p. 248~249 °C) and 250 g was dissolved in 1500 mL of formamide, maintained at 150~170 °C for 5 h. The solution was allowed to cool to R.T., and the precipitate wasfiltered and washed to give a white solid (92percent, m.p. 306~307 °C). Thus, 2 was succesfully obtained inan overall yield of 67percent. IR (KBr), (cm1): 3188.6, 1643.4 (NH), 1680.3 (C=O); ESI-MS (m/z): 256.9[M - H]-, 258.9 [M + 2 - H]; 1H-NMR (300 MHz, DMSO-d6), δ (ppm): 12.50 (br, 1H), 8.15 (s, 1H), 8.14 (s, 1H), 8.05 (s, 1H).

7-Bromo-6-chloro-4(3H)-quinazolinone is an important intermediate in the manufacturing of the anticoccidial drug (coccidiostat) halofuginone (Tempostatin).