Mechanism of Cu-catalyzed iododeboronation: A description of ligand-enabled transmetalation, disproportionation, and turnover in Cu-mediated oxidative coupling reactions

We report a combined experimental and computational study of the mechanism of the Cu-catalyzed arylboronic acid iododeboronation reaction. A combination of structural and DFT analyses has allowed determination of the identity of the reaction pre-catalyst and the first complete description of the catalytic cycle. Key findings include a rationale for ligand stoichiometry related to key turnover events – the ligand facilitates transmetalation via H-bonding to an organoboron boronate generated in situ and ligand loss/gain is integral to the key oxidative events. These data provide a framework for understanding ligand effects on these key mechanistic processes, which underpin several classes of Cu-mediated oxidative coupling reactions.