Cu(ii)-nitroxyl radicals as catalytic galactose oxidase mimics

Results from Hammett correlation studies and primary kinetic isotope effects for the CuCl–TEMPO catalysed aerobic benzyl alcohol oxidations are inconsistent with an oxoammonium based mechanism. We postulate a copper-mediated dehydrogenation mechanism, in which TEMPO regenerates the active Cu(II)-species. This mechanism is analogous to that observed for Galactose Oxidase and mimics thereof.