A surprising formation of novel bridged bis-benzimidazoles by oxidation of diaminoquinoxalines

Article abstract of DOI:10.1515/znb-2012-0411

A synthesis of novel hexacyclic bis-benzimidazoles 6 starting from 2,3-diarylamino-quinoxalines via an oxidative cyclization cascade is described. These very stable and high-melting derivatives are featured by their strong fluorescence in the blue region of the visible spectrum. The cyclization reaction between 2,3-dichloroquinoxaline and 1,2-phenylenediamine did not lead to derivatives of type 6. In this case, only fluoflavine 7 was isolated quantitatively.