Copper(I)-α-ketocarboxylate complexes: Characterization and O ₂ reactions that yield copper-oxygen intermediates capable of hydroxylating arenes

A series of copper(I)-α-ketocarboxylate complexes have been prepared and shown to exhibit variable coordination modes of the α-ketocarboxylate ligand. Reaction with O₂ induces decarboxylation of this ligand, and the derived copper-oxygen intermediate(s) has been intercepted, resulting in hydroxylation of an arene substituent on the supporting N-donor ligand. Theoretical calculations have provided intriguing mechanistic notions for the process, notably implicating hydroxylation pathways that involve novel [Cu^I-OOC(O)R] and [Cu^II-O^-• ↔ Cu^III=O^2-]⁺ species.