Copper(I)-α-ketocarboxylate complexes:: Characterization and O2 reactions that yield copper-oxygen intermediates capable of hydroxylating arenes

A series of copper(I)-alpha-ketocarboxylate complexes have been prepared and shown to exhibit variable coordination modes of the alpha-ketocarboxylate ligand. Reaction with O-2 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-center dot <-> CUIII=O2-](+) species.