Cover Picture: Polyazaacenes – On the Way to Stable, Fluorescent and Redox‐Active Derivatives (Eur. J. Org. Chem. 8/2007)

Abstract

The cover picture shows the dyotropic rearrangement of 1,4,5,8‐tetraazafulvalenes into pyrazino‐[2,3‐b]pyrazines. In the case of Ar = 4‐tert‐butylphenyl, the products were immediately transformed, in the presence of oxygen, into derivatives of octaazahexacene through a cascade reaction. These highly ring‐fused compounds display a strong red fluorescence in solution and, in addition, can easily be reduced reversibly. In contact with air, the yellow fluorescent leuco compound formed quickly reoxidized, which is visible by red fluorescent streaks. Details are discussed in the article by R. Beckert et al. on p. 1237 ff.