Mechanistic Insight into the Aromatic Hydroxylation by High-Valent Iron(IV)-oxo Porphyrin π-Cation Radical Complexes

• Published in: Journal of organic chemistry Vol. 72; no. 16; pp. 6301 - 6304
• Main Authors: Kang, Min-Jung, Song, Woon Ju, Han, Ah-Rim, Choi, Young S, Jang, Ho G, Nam, Wonwoo
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 03.08.2007
• Subjects: Cations; Chemistry; Chemistry, Organic - methods; Exact sciences and technology; Free radicals chemistry; Heterocyclic compounds; Heterocyclic compounds with several n hetero atoms in the same ring, in separated rings or in fused rings; Iron - chemistry; Kinetics; Kinetics and mechanisms; Models, Chemical; Molecular Conformation; Organic chemistry; Porphyrins - chemistry; Preparations and properties; Reactivity and mechanisms; Spectrophotometry, Ultraviolet; Time Factors; Cationic complex; Iron Complexes; Radical cation; Hydroxylation; Isotope labelling; Transition metal; Iron; Transition metal Complexes; Ketone; Kinetic isotope effect; Hammett function; Organic free radical; Reaction mechanism; Aromatic compound; Oxidation; Metalloporphyrin
• ISSN: 0022-3263; 1520-6904
• DOI: 10.1021/jo070557y

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.