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 SNAr 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.
Key words
dibenzothiophene - dibenzofuran - carbazole - heterocycles - palladium - phenols