Oxidation of 2-aminophenol with molecular oxygen and hydrogen peroxide catalyzed by water soluble metalloporphyrins

El-Khalafy, Sahar H.; Hassanein, M.

doi:10.1016/j.molcata.2012.06.002

Cited by 19 publications

(9 citation statements)

References 43 publications

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“…Attack of the imine N atom of 4 on the para position (w.r.t to the carbonyl group) of another molecule of 4 , followed by 1,5-sigmatropic migration of a H atom, subsequent deprotonation and oxidation would lead to formation of the phenoxazine product 3. Such a pathway using ortho -aminophenol (OAP) has been reported before using manganese porphyrins that use H 2 O 2 as the external oxidant [36]. In our case, the deprotonation and oxidation steps probably took place in air during column chromatography.…”

Section: Resultssupporting

confidence: 63%

“…Compound 3 has anti-inflammatory and immunomodulatory properties and is, therefore, valuable for its medicinal properties. As mentioned before, other reported methods involving metalloporphyrin-catalyzed synthesis of 3 from OAP make use of more powerful oxidants like hydrogen peroxide, and are believed to be formed via different mechanisms [36].…”

Section: Resultsmentioning

confidence: 99%

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Porphyrin Cobalt(III) “Nitrene Radical” Reactivity; Hydrogen Atom Transfer from Ortho-YH Substituents to the Nitrene Moiety of Cobalt-Bound Aryl Nitrene Intermediates (Y = O, NH)

2016

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Abstract:In the field of cobalt(II) porphyrin-catalyzed metallo-radical reactions, organic azides have emerged as successful nitrene transfer reagents. In the pursuit of employing ortho-YH substituted (Y = O, NH) aryl azides in Co(II) porphyrin-catalyzed nitrene transfer reactions, unexpected hydrogen atom transfer (HAT) from the OH or NH 2 group in the ortho-position to the nitrene moiety of the key radical-intermediate was observed. This leads to formation of reactive ortho-iminoquinonoid (Y = O) and phenylene diimine (Y = NH) species. These intermediates convert to subsequent products in non-catalyzed reactions, as is typical for these free organic compounds. As such, the observed reactions prevent the anticipated cobalt-mediated catalytic radical-type coupling of the nitrene radical intermediates to alkynes or alkenes. Nonetheless, the observed reactions provide valuable insights into the reactivity of transition metal nitrene-radical intermediates, and give access to ortho-iminoquinonoid and phenylene diimine intermediates from ortho-YH substituted aryl azides in a catalytic manner. The latter can be employed as intermediates in one-pot catalytic transformations. From the ortho-hydroxy aryl azide substrates both phenoxizinones and benzoxazines could be synthesized in high yields. From the ortho-amino aryl azide substrates azabenzene compounds were obtained as the main products. Computational studies support these observations, and reveal that HAT from the neighboring OH and NH 2 moiety to the nitrene radical moiety has a low energy barrier.

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Section: Resultssupporting

confidence: 63%

Section: Resultsmentioning

confidence: 99%

Porphyrin Cobalt(III) “Nitrene Radical” Reactivity; Hydrogen Atom Transfer from Ortho-YH Substituents to the Nitrene Moiety of Cobalt-Bound Aryl Nitrene Intermediates (Y = O, NH)

2016

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“…The native enzyme is known to require 4-5 copper centres for maximum activity and less number of copper centres reduces the activity [156]. However, the model complexes of PHS are mostly rather simple mononuclear complexes of transition metal [71,[85][86][87][88][89][90][91][92][93][94][95]167]. There is only one report of a tetranuclear Cu II complex as model of phenoxazinone synthase by Mukherjee et al In that report the ligand is also attributed to be important for the activity due to its redox non-innocent nature [94].…”

Section: Oxidative Coupling Of 2-aminophenol (Oap)mentioning

confidence: 99%

“…PHS mimics cannot be found as much as CO but yet are well studied with 3d-metals viz. Co [85][86][87][88][89][90][91][92], Mn [71,89,91,93], Cu [94], Fe [91,95] complexes using 2-aminophenol as substrate. We investigated the possible reactive oxygen species (ROS) involved for each of the metal ions.…”

Section: Introductionmentioning

confidence: 99%

Investigation of 3d-transition metal acetates in the oxidation of substituted dioxolene and phenols

Dey

Mukherjee

2015

Journal of Molecular Catalysis A: Chemical

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“…The process of biological oxidation is carried out with metalloenzymes, such as phenoxazinone synthase, which contains copper and occurs naturally in the bacterium Streptomyces antibioticus. This phenoxazinone synthase enzyme catalyzes the oxidative coupling of a range of different substituted 2-aminophenols (OAPHs) to the phenoxazinone chromophore (APX) -the final step in the biosynthesis of actinomycin D. This is important because actinomycin D is needed for the clinical treatment of tumours, especially Wilms' tumour, and gestational choriocarcinoma (Bocian et al, 2019;Bakshi et al, 2012;El-Khalafy & Hassanein, 2012;Panja et al, 2014;Simá ndi et al, 2003).…”

Section: Introductionmentioning

confidence: 99%

Bases, solvates and salts: new benzimidazole- and pyridine-scaffolded ligands

et al. 2020

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The intermolecular interactions in the structures of a series of Schiff base ligands have been thoroughly studied. These ligands can be obtained in different forms, namely, as the free base 2‐[(2E)‐2‐(1H‐imidazol‐4‐ylmethylidene)‐1‐methylhydrazinyl]pyridine, C10H11N5, 1, the hydrates 2‐[(2E)‐2‐(1H‐imidazol‐2‐ylmethylidene)‐1‐methylhydrazinyl]‐1H‐benzimidazole monohydrate, C12H12N6·H2O, 2, and 2‐{(2E)‐1‐methyl‐2‐[(1‐methyl‐1H‐imidazol‐2‐yl)methylidene]hydrazinyl}‐1H‐benzimidazole 1.25‐hydrate, C13H14N6·1.25H2O, 3, the monocationic hydrate 5‐{(1E)‐[2‐(1H‐1,3‐benzodiazol‐2‐yl)‐2‐methylhydrazinylidene]methyl}‐1H‐imidazol‐3‐ium trifluoromethanesulfonate monohydrate, C12H13N6+·CF3O3S−·H2O, 5, and the dicationic 2‐{(2E)‐1‐methyl‐2‐[(1H‐imidazol‐3‐ium‐2‐yl)methylidene]hydrazinyl}pyridinium bis(trifluoromethanesulfonate), C10H13N52+·2CF3O3S−, 6. The connection between the forms and the preferred intermolecular interactions is described and further studied by means of the calculation of the interaction energies between the neutral and charged components of the crystal structures. These studies show that, in general, the most important contribution to the stabilization energy of the crystal is provided by π–π interactions, especially between charged ligands, while the details of the crystal architecture are influenced by directional interactions, especially relatively strong hydrogen bonds. In one of the structures, a very interesting example of the nontypical F…O interaction was found and its length, 2.859 (2) Å, is one of the shortest ever reported.

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Oxidation of 2-aminophenol with molecular oxygen and hydrogen peroxide catalyzed by water soluble metalloporphyrins

Cited by 19 publications

References 43 publications

Porphyrin Cobalt(III) “Nitrene Radical” Reactivity; Hydrogen Atom Transfer from Ortho-YH Substituents to the Nitrene Moiety of Cobalt-Bound Aryl Nitrene Intermediates (Y = O, NH)

Porphyrin Cobalt(III) “Nitrene Radical” Reactivity; Hydrogen Atom Transfer from Ortho-YH Substituents to the Nitrene Moiety of Cobalt-Bound Aryl Nitrene Intermediates (Y = O, NH)

Investigation of 3d-transition metal acetates in the oxidation of substituted dioxolene and phenols

Bases, solvates and salts: new benzimidazole- and pyridine-scaffolded ligands

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