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The isatoic anhydride and acetic anhydride were reacted under the condition described for the preparation of 2-methyl-4H-3,1-benzoxazine-4-one. The pyridine was distilled from the reaction mixture under reduced pressure. The crude reaction product was taken up in 100 ml of o-xylene and placed in a 200 ml one-necked flask equipped with a Dean-Stark trap and a reflux condenser. The o-toluidine was added to the xylene solution. The reaction mixture was heated to reflux for 4 hours. 1.8 ml of water was collected in the Dean-Stark trap. The xylene was removed from the reaction product by distillation under reduced pressure. The resulting residue was crystallized twice from methanol to give 16 parts (64% yield) of 2-methyl-3-(o-tolyl)-quinazoline-4 (3H)-one with m.p. 113°-115° C. The reaction product was characterized by melting point, IR and NMR.

1. distillationThe pyridine was distilled from the reaction mixture under reduced pressure
2. customThe crude reaction product
3. customplaced in a 200 ml one-necked flask
4. customequipped with a Dean-Stark trap and a reflux condenser
5. temperatureThe reaction mixture was heated
6. temperatureto reflux for 4 hours
7. custom1.8 ml of water was collected in the Dean-Stark trap
8. customThe xylene was removed from the reaction product by distillation under reduced pressure
9. customThe resulting residue was crystallized twice from methanol