Synthesis of new phthalazinedione derivatives

In the past few decades, the synthesis of new heterocyclic compounds has been a subject of great interest due to their wide applicability. Among a large variety of heterocyclic compounds, heterocycles containing phthalazine moiety were reported to possess anticonvulsant, cardiotonic, and vasorelaxant activities. Therefore, a number of methods have been reported for the synthesis of phthalazine derivatives. Despite the available methods, the development of new synthetic methods for the efficient preparation of heterocycles containing phthalazine ring fragment is therefore an interesting challenge. With these precedents and with the aim of preparing new derivatives with potential pharmacological activity, we have synthesized new phthalazinedione derivatives by introducing halogenoalkyl substituents in one of the NH-nucleophilic groups. So, we started with 4-chloro-phthalic anhydride, which reacted with methyl- hydrazine, in MW mild conditions. After purification, we obtained two different isomers of phthalizediones, 8-chloro-2-methyl-2, 3-dihydro-phthalazine-1, 4-dione and 8-chloro-3-methyl-2, 3-dihydro-phthalazine-1,4-dione. Then halogenoalkyl substituents with different chain length were introduced in the nitrogen group in a very efficient way. Finally halogen atom of alkyl chains was replaced by an azide group. The described synthetic route will allow us to condense a nitrogen heterocyclic ring on the phatalazinone moiety and obtain a new tricyclic scaffold with promising pharmacological properties.