Model systems for cytochrome P450-dependent mono-oxygenases. Part 5. Amine oxidation. Part 17. Oxidative N-dealkylation of tertiary amines by metalloporphyrin-catalysed model systems for cytochrome P450 mono-oxygenases

Abstract

NN-Dimethylbenzylamine has been oxidatively demethylated to N-methylbenzylamine and debenzylated to benzaldehyde by iodosylbenzene and by t-butyl hydroperoxide catalysed by tetraphenylporphyrinato-iron(III) or -manganese(III) chloride. The influence of substituents on the aromatic ring and of deuteriation of the benzylic hydrogens on the relative reactivity of the substrates and on the product distribution has been studied. The results suggest that the initial step in the metalloporphyrin-catalysed iodosylbenzene oxidations is an electron-transfer from the amine to a high valent oxometal species, whereas, with t-butyl hydroperoxide the mechanism is one of hydrogen abstraction from the amine by the t-butoxyl radical. The mechanisms of the subsequent steps are discussed.