Unusual Products from Oxidation of Naphthalene Diimides

Transforming the naphthalene diimide (NDI) core into unusual aromatic systems has large potential for applications in which current NDI‐based systems show promise. Treatment of N , N ‐dialkylNDIs under mild oxidizing conditions with ruthenium(III) chloride and sodium periodate affords the corresponding 1,4‐diones in good yield. Interestingly, while aliphatic substituents at the N ‐imide positions allowed oxidation to take place easily, the presence of neutral, electron‐rich or electron‐deficient phenyl groups retarded the oxidation process under these reaction conditions. The chemistry of the 1,4‐dione is then explored through reduction and condensation reactions. In two examples, reaction of the 1,4‐dione with diamines gives an unusual, ring‐contracted product 20 , which has a high quantum yield. Additionally, the 1,4‐dione can be converted into larger heterocycles such as 21 and 22 featuring an isoquinoline core. The 1,4‐diones and their products have been investigated by spectroscopy, cyclic voltammetry, theoretical studies, and X‐ray crystallography. The results obtained demonstrate the potential of the 1,4‐dione to serve as an invaluable precursor for NDI‐based research.