On the question of the transformation of amino acids into aldimine N-oxides (nitrones): molecular electron density theory (MEDT) considerations

Abstract The molecular mechanism of the oxidation process of imine derivatives of amino acids by peracids was explored on the basis of the ωB97X-D/6-311G(d,p) (PCM) quantum chemical computations. Analysis in the framework of the conceptual density functional theory (CDFT) presents that in these lowly polar reactions all imines can be classified as nucleophilic agents with the most nucleophilic center situated on the nitrogen atom of the imine moiety, while tested peracids present an electrophilic character. The exploration of reaction profiles shows without a doubt, that the considered processes are realized as stepwise reactions with the oxaziridine-type intermediates. The nature of substituents in the peracid molecule as well as the polarity of the solvent influence to a small degree the reaction’s kinetics and completely do not influence the general oxidation mechanism. Natural charges in conjunction with the electron localization function (ELF) results allow us to classify the studied nitrones as zw -type of three atom components (TACs). Graphical abstract