The invention discloses a method for synthesizing 7-bromo-6-chloro-4-
quinazolinone. The method comprises the following steps of: (1) dripping liquid
bromine into suspension of m-
chlorotoluene, n-
butyl bromide and
anhydrous ferric trichloride, washing with water and a saturated
sodium bicarbonate solution, distilling, and recrystallizing; (2) mixing water,
pyridine,
tertiary butanol and the like, dissolving a product in the step (1) and
potassium permanganate in a
mixed solution, heating and refluxing, continuously adding
potassium permanganate, filtering, washing with boiling water, regulating the pH value, cooling and filtering; (3) dissolving a product in the step (2) in a
mixed solution of stronger
ammonia water and
ethyl acetate at
room temperature under the protection of
nitrogen, dripping into suspension of cuprous
oxide and stronger
ammonia water, adding
ethylene diamine tetraacetic acid (EDTA), regulating the pH value, evaporating the
ethyl acetate, cooling, and performing suction
filtration; and (4) mixing a product in the step (3) and
formamide, dissolving in
dimethyl formamide (DMF), heating and refluxing, cooling, precipitating, filtering, washing with absolute
ethanol, and recrystallizing by using
ethylene glycol
monomethyl ether. The method has the advantages of cheap raw materials, simplified steps and practicable process, avoids 6-bromoisatin, and is suitable for industrial production.