Bio-inspired amino acid oxidation by a non-heme iron catalyst

This study reports the kinetics and mechanism of Fe(III)-catalyzed oxidative decarboxylation and deamination of a series of acyclic (α-aminoisobutyric acid, α-(methylamino)isobutyric acid, alanine, norvaline, and 2-aminobutyric acid) and cyclic (1-aminocyclopropane-1-carboxylic acid, 1-amino-1-cyclobutanecarboxylic acid, 1-aminocyclopentanecarboxylic acid, and 1-aminocyclohexanecarboxylicacid) amino acids using hydrogen peroxide, t-butyl hydroperoxide, iodosylbenzene, m-chloroperbenzoic acid, and peroxomonosulphate as oxidant in 75% DMF–25% water solvent mixture. Model complex [FeIVO(SALEN)]•+ (SALENH2: N,N′-bis(salicylidene)ethylenediamine) was generated by the reaction of FeIII(SALEN)Cl and H2O2 in CH3CN at 278 K as reported earlier. This method provided us high-valent oxoiron species, stable enough to ensure the direct observation of the reaction with amino acids.

Graphical abstract[FeIII(SALEN)Cl] (SALENH2: N,N′-bis(salicylidene)ethylenediamine) is an active and selective catalyst in the oxidation of a series of cyclic and acyclic amino acids to ethylene and carbonyls and thus serves as functional models for ACC oxidase.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Kinetics of Fe(III)-catalyzed oxidation of amino acids with various oxidants. ► Stoichiometric oxidation of ACC with high valent iron-oxo intermediate. ► Suggested mechanism for the ACC oxidase.