Synthesis of Dibenzothiophene, Dibenzofuran and Carbazole Donor-Acceptor Chromophores

We present efficient synthetic protocols for functionalizing dibenzothiophene, dibenzofuran, and carbazole with hydroxy and nitro or cyano groups. The synthesis of these donor–acceptor chromophores is based on a key Suzuki–Miyaura coupling using an appropriately substituted aromatic boronic acid. Subsequent intramolecular S_NAr reaction allows formation of the dibenzothiophene and dibenzofuran scaffolds, while a carbon–hydrogen activation reaction is employed to afford the carbazole. A final demethylation step unmasks the phenol moiety of the tricyclic chromophores. The UV/Vis absorption properties of the phenol and phenolate forms of these chromophores are also studied.