Issue 21, 2016

Substrate-dependent aromatic ring fission of catechol and 2-aminophenol with O2 catalyzed by a nonheme iron complex of a tripodal N4 ligand

Abstract

The catalytic reactivity of an iron(II) complex [(TPA)FeII(CH3CN)2]2+ (1) (TPA = tris(2-pyridylmethyl)amine) towards oxygenative aromatic C–C bond cleavage of catechol and 2-aminophenol is presented. Complex 1 exhibits catalytic and regioselective C–C bond cleavage of 3,5-di-tert-butylcatechol (H2DBC) to form intradiol products, whereas it catalyzes extradiol-type C–C bond cleavage of 2-amino-4,6-di-tert-butylphenol (H2AP). The catalytic reactions are found to be pH-dependent and the complex exhibits maximum turnovers at pH 5 in acetonitrile–phthalate buffer. An iron(III)–catecholate complex [(TPA)FeIII(DBC)]+ (2) is formed in the ring cleavage of catechol. In the extradiol-type cleavage of H2AP, an iron(III)–2-iminobenzosemiquinonate complex [(TPA)FeIII(ISQ)]2+ (3) (ISQ = 4,6-di-tert-butyl-2-iminobenzosemiquinonate radical anion) is observed in the reaction pathway. This work shows the importance of the nature of ‘redox non-innocent’ substrates in governing the mode of ring fission reactivity.

Graphical abstract: Substrate-dependent aromatic ring fission of catechol and 2-aminophenol with O2 catalyzed by a nonheme iron complex of a tripodal N4 ligand

Supplementary files

Article information

Article type
Paper
Submitted
18 Nov 2015
Accepted
14 Apr 2016
First published
19 Apr 2016

Dalton Trans., 2016,45, 8835-8844

Substrate-dependent aromatic ring fission of catechol and 2-aminophenol with O2 catalyzed by a nonheme iron complex of a tripodal N4 ligand

T. R. Lakshman, S. Chatterjee, B. Chakraborty and T. K. Paine, Dalton Trans., 2016, 45, 8835 DOI: 10.1039/C5DT04541J

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