Oxygenative cleavage of catechols including protocatechuic acid with molecular oxygen in water catalysed by water-soluble non-heme iron(iii) complexes in relevance to catechol dioxygenases

Abstract

Catechol dioxygenase model oxygenations have been performed for the first time in water by using water-soluble nonheme iron(III) complexes, enabling the oxygenation of protocatechuic acid and other catechols.

Gas Production in the Bromate−Pyrocatechol Oscillator

“…Further oxidation to the dicarboxylic acid by a Baeyer−Villiger - like process to give a dicarboxylic acid ( 3a or 3b ) and subsequent Michael-type addition−elimination of either of these intermediates would afford furanone-carboxylic acid 4 (Scheme , eqs 4 and 4a). The catechol to dicarboxylic acid to furanone-carboxylic acid transformation under oxidative conditions has several precedents . It is based on these precedents that oxidation prior to bromination is proposed, as initial electrophilic bromination of the catechol would be expected to result in bromine incorporation on the furanone ring.…”

Dioxygen Activation at Mononuclear Nonheme Iron Active Sites: Enzymes, Models, and Intermediates

“…Using the fast-reacting Fe(TPA) complex), they demonstrated that the catalyst was even capable of cleaving otherwise inert chorocatechol substrates (Figure ) . This reaction in fact models the chemistry of chlorocatechol dioxygenases, intradiol-cleaving enzymes closely related to 3,4-PCD but less well characterized. , Funabiki also introduced sulfonate groups into the TPA ligand to afford water-soluble iron catalysts that oxidatively cleave a range of water-soluble catechol substrates such as chlorocatechols and protocatechuic acid. , However, addition of excess TPA ligand is required for these reactions, and detailed structural characterization of these metal complexes is lacking. Further studies would be required in order to have a full understanding of this highly active system.…”

“…58,59 Funabiki also introduced sulfonate groups into the TPA ligand to afford watersoluble iron catalysts that oxidatively cleave a range of water-soluble catechol substrates such as chlorocatechols and protocatechuic acid. 57,60 However, addition of excess TPA ligand is required for these reactions, and detailed structural characterization of these metal complexes is lacking. Further studies would be required in order to have a full understanding of this highly active system.…”

Substrate-dependent aromatic ring fission of catechol and 2-aminophenol with O2catalyzed by a nonheme iron complex of a tripodal N4ligand

“…However, reports on catalytic functional models of catechol dioxygenases or 2-aminophenol dioxygenases are rare. [51][52][53][54][55] With an objective to develop catalytic functional models of catechol cleaving dioxygenases and 2-aminophenol dioxygenases, we have investigated the iron-catecholate/2-aminophenolate chemistry of a tripodal N 4 ligand (Scheme 2). In this manuscript, we report the catalytic and selective C-C bond cleavage reaction of 3,5-di-tert-butylcatechol (H 2 DBC) and 2-amino-4,6-di-tert-butylphenol (H 2 AP) by an iron(II) complex [(TPA)Fe II (CH 3 CN) 2 ] 2+ (1) of the tris(2-pyridylmethyl)amine (TPA) ligand.…”