Copper−Hydroperoxo-Mediated N-Debenzylation Chemistry Mimicking Aspects of Copper Monooxygenases

A substantial oxidative N-debenzylation reaction along with PhCHO formation occurs from a hydroperoxo−copper(II) complex that has a dibenzylamino substrate (N(CH2Ph)2 appended as a substituent on one pyridyl group of its tripodal tetradentate TMPA (also TPA, (2-pyridylmethyl)amine)) ligand framework. During the course of the (LN(CH2Ph)2)CuII(−OOH) reactivity, the formation of a substrate and a −OOH-derived (an oxygen atom) alkoxo CuII(−OR) complex occurs. The observation that the same CuII(−OR) species occurs from CuΙ/PhIO chemistry suggests the possibility that a copper−oxo (cupryl) reactive intermediate forms during the alkoxo species formation; new ESI-MS data provide further support for this high-valent intermediate. A net H atom abstraction chemistry is proposed on the basis of the kinetic isotope effect studies provided here and the previously published study for a closely related CuII(−OOH) species incorporating dimethylamine (N(CH3)2) as the internal substrate; the CuΙ/PhIO reactivity with similar isotope effect results provides further support. The reactivity of these chemical systems closely resembles the proposed oxidative N-dealkylation mechanisms that are effected by the copper monooxygenases, dopamine β-monooxygenase (DβM) and peptidylglycine-α-hydroxylating monooxygenase (PHM).