Synthesis of soluble oligocarbazole derivatives

3,6-Disubstituted carbazole building blocks are coupled via copper-catalyzed Ullmann reactions to afford trimeric and heptameric carbazoles with excellent solubilites in organic solvents. Alternatively, oligomeric carbazoles with phenylene spacers, that are more stable towards oxidation, can be obtained via palladium-catalyzed Suzuki coupling reactions.