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.