2,3-Benzoxazin-1-ones. Part I. Reactions of aluminium chloride, sulphuric acid, and hydrazine hydrate with 4-aryl-2,3-benzoxazin-1-ones

4-Aryl-2,3-benzoxazin-1-ones (II) reacted with anhydrous aluminium chloride in hot nitrobenzene or chlorobenzene to give the corresponding N-arylphthalimides (V). However, reactions in benzene, toluene, and p-xylene gave the corresponding o-aroylanilides (VII). When heated with dilute sulphuric acid, and with hydrazine in acetic acid, the benzoxazinones (II) were converted into phthalic acid and 4-arylphthalazin-1-ones (IX), respectively.