4.2. Synthesis of Quinazolinone Derivatives

(8) 3-amino-2-methyl-4(3H)-quinazolinone: Hydrazine hydrate (10.00 mL, 99%) was added to a solution containing 2-methyl-4H-3,1-benzoxazin-4-one (6) (3.00 g, 20 mmol) and absolute ethanol (15.00 mL). The mixture was refluxed for 27 h, cooled, and the resulting precipitate was filtered and recrystallized from water.

(9) 3-amino-2-phenyl-4(3H)-quinazolinone: A mixture of 2-phenyl-4H-1,3-benzoxazin-4-one (7) (100 mg, 0.45 mmol) and hydrazine hydrate (4.0 mL, 82 mmol) was refluxed for 25 min at 200–250 °C using an oil bath. The mixture was then cooled to room temperature and poured over ice for the collection of the precipitate. The resulting solid was then separated and purified using ethanol [17].