Mechanistic insight into the aromatic hydroxylation by high-valent iron(IV)-oxo porphyrin π-cation radical complexes

(Chemical Equation Presented) Mechanistic studies of the aromatic hydroxylation by high-valent iron(IV)-oxo porphyrin π-cation radicals revealed that the aromatic oxidation involves an initial electrophilic attack on the π-system of the aromatic ring to produce a tetrahedral radical or cationic σ-complex. The mechanism was proposed on the basis of experimental results such as a large negative Hammett ρ value and an inverse kinetic isotope effect. By carrying out isotope labeling studies, the oxygen in oxygenated products was found to derive from the iron-oxo porphyrin intermediates.