Palladium-Catalyzed Synthesis of α-Diketones from Acylchromates, Iodoarenes, and Carbon Monoxide

A three-component coupling of tetramethylammonium pentacarbonyl(acyl)chromates, aryl iodides, and CO takes place under CO atmosphere in the presence of a catalytic amount of Pd(PPh3)4 to afford the corresponding unsymmetrical α-diketones in good yield. By performing the reaction under argon atmosphere, unsymmetrical ketones are prepared instead of α-diketones.