Aerobic intramolecular carbon–hydrogen bond oxidation promoted by Cu(i) complexes

Abstract

The oxidation of C–H bonds by copper centres in enzymes with molecular oxygen takes place in nature under ambient conditions. Herein we report a similar transformation in which under ambient pressure and temperature (1 atm, 25 °C) the complex Tp^MsCu(THF) (Tp^Ms = hydrotris(3-mesityl-pyrazol-1-yl)borate) undergoes the intramolecular oxidation of an alkylic C–H bond with O₂, leading to the formation of a trinuclear compound where alkoxy and hydroxyl ligands are bonded to the copper centres, as inferred from X-ray studies. The presence of adventitious Cu(0) derived from the partial decomposition of initial Tp^MsCu(THF) facilitates the formation of such a trinuclear compound. DFT studies support the reaction taking place through a Cu(III) alkoxy-hydroxyl copper intermediate.