Synthesis of new substituted 5-amino-8H-phthalazino[1,2-b]quinazolin-8-one derivatives

A series of novel substituted 5-amino-8H-phthalazino[1,2-b] quinazolin-8-one derivatives synthesised by condensation of different amines with 5-chloro-8H-phthalazino[1,2-b] quinazolin-8-one, which was prepared from methyl 2-aminobenzoate by condensation with hydrazine hydrate and then cyclisation with a phthalic anhydride in N, N-dimethylacetamide at refluxing condition. The intermediate and target compounds were obtained in good yields and were easily purified by filtration or recrystallisation.