Synthesis of Aza‐indeno‐aza‐fluoranthene and Constitutional Isomers by Ring‐Size Selective C–H Activation

The fluoranthene motif combines a planar geometry with electron‐deficient character, rendering fluoranthene and its larger congeners like indenofluoranthene suitable compounds for designing n ‐semiconducting materials for applications in organic electronics. However, examples in which their opto‐ and electrochemical properties are tuned through selective five‐ or six‐membered ring annelation, as well as by isosteric nitrogen substitution of a C–H unit within the fluoranthene core, remain scarce. Here the structure–property‐relationships of a series of aza‐fluoranthene‐derived constitutional isomers as well as their syntheses by selective Pd‐catalyzed indeno‐ or benzannelation of the same precursor is described.