Oxygen as Oxidant in Palladium-Catalyzed Inter- and Intramolecular Coupling Reactions

Carbazoloquinones, carbazole, dibenzofuran, and related compounds (see scheme) have been synthesized from the respective noncyclic aromatic compounds with catalytic amounts of palladium and oxygen as the single oxidant. Intermolecular couplings of aromatic systems can also be performed with this catalytic system.