Mechanism of the CuII-catalyzed benzylic oxygenation of (aryl)(heteroaryl)methanes with oxygen

摘要: A mechanistic study of the copper-catalyzed oxidation methylene group aryl(di)azinylmethanes was performed. Initial reaction rates were measured making use in situ IR monitoring and a kinetic analysis executed. The proved to be first order oxygen concentration. For substrate acid concentration, saturation kinetics due O2 mass transfer limitation observed. occurrence further confirmed by examining effect stirring rate on initial rate. Interestingly, concentration catalyst shows that higher loadings result maximal rate, followed initially steady decrease subsequently plateau when is increased further. Mass dinuclear catalytically active species rationalizes this hitherto unprecedented behavior. Continuous-wave pulsed electron paramagnetic resonance methods used characterize catalytic present solution during presence both mono- copper species. Analysis diverse scope points towards imine–enamine tautomerization as crucial process reaction. DFT calculations these equilibrium constants (pKeq) provided us with qualitative tool predict whether or not viable for under conditions developed.