Synthesis of Carbazole-Fused Azaborines via a Pd-Catalyzed C-H Activation-Cyclization Reaction

Carbazole-fused azaborines were synthesized via a Buchwald-Hartwig amination followed by a Pd-catalyzed C-H activation-cyclization reaction. These azaborines exhibited red-shifted absorptions and photoluminescence emissions compared to those of dibenzoazaborines, suggesting the efficient HOMO-LUMO energy gap decrease by the carbazole-annulation. The carbazole-fused azaborines showed improved electrochemical stability compared with the previously reported dibenzoazaborine derivatives.