A method for the Pd-catalyzed carbonylation of aryl bromides has been developed using Xantphos as the ligand. This method is effective for the direct synthesis of Weinreb amides, 1 degrees and 2 degrees benzamides, and methyl esters from the corresponding aryl bromides at atmospheric pressure. In addition, a putative catalytic intermediate, (Xanphos)Pd(Br)benzoyl, was prepared and an X-ray crystal structure was obtained revealing an unusual cis-coordination mode of Xantphos in this palladium-acyl complex.
“Palladium-Catalyzed Carbonylation Reactions of Aryl Bromides at Atmospheric Pressure: A General System Based on Xantphos”, J. Org. Chem., 2008, 73(18), 7102-7107.