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Oxoiron(IV) porphyrin π-cation radical complexes with a chameleon behavior in cytochrome P450 model reactions

Title
Oxoiron(IV) porphyrin π-cation radical complexes with a chameleon behavior in cytochrome P450 model reactions
Authors
Woon J.S.Yon O.R.Song R.Nam W.
Ewha Authors
남원우
SCOPUS Author ID
남원우scopus
Issue Date
2005
Journal Title
Journal of Biological Inorganic Chemistry
ISSN
0949-8257JCR Link
Citation
Journal of Biological Inorganic Chemistry vol. 10, no. 3, pp. 294 - 304
Indexed
SCIE; SCOPUS WOS scopus
Document Type
Article
Abstract
There is an intriguing, current controversy on the involvement of multiple oxidizing species in oxygen transfer reactions by cytochromes P450 and iron porphyrin complexes. The primary evidence for the "multiple oxidants" theory was that products and/or product distributions obtained in the catalytic oxygenations were different depending on reaction conditions such as catalysts, oxidants, and solvents. In the present work, we carried out detailed mechanistic studies on competitive olefin epoxidation, alkane hydroxylation, and C=C epoxidation versus allylic C-H hydroxylation in olefin oxygenation with in situ generated oxoiron(IV) porphyrin π-cation radicals (1) under various reaction conditions. We found that the products and product distributions were markedly different depending on the reaction conditions. For example, 1 bearing different axial ligands showed different product selectivities in competitive epoxidations of cis-olefins and trans-olefins and of styrene and para-substituted styrenes. The hydroxylation of ethylbenzene by 1 afforded different products, such as 1-phenylethanol and ethylbenzoquinone, depending on the axial ligands of 1 and substrates. Moreover, the regioselectivity of C=C epoxidation versus C-H hydroxylation in the oxygenation of cyclohexene by 1 changed dramatically depending on the reaction temperatures, the electronic nature of the iron porphyrins, and substrates. These results demonstrate that 1 can exhibit diverse reactivity patterns under different reaction conditions, leading us to propose that the different products and/or product distributions observed in the catalytic oxygenation reactions by iron porphyrin models might not arise from the involvement of multiple oxidizing species but from 1 under different circumstances. This study provides strong evidence that 1 can behave like a "chameleon oxidant" that changes its reactivity and selectivity under the influence of environmental changes. © SBIC 2005.
DOI
10.1007/s00775-005-0641-9
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자연과학대학 > 화학·나노과학전공 > Journal papers
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