Biomimetic oxygenation

McLain, J. L. Lee, J. Groves, J. T. Biomimetic oxygenations related to cytochrome P450 metal- and metal-peroxo intermediates, Biomimetic Oxidations Catalyzed by Transition Metal Complexes , Ed. Meunier, B. Imperial College Press London, 2000, pp. 91-169. 

A study of biomimetic oxygenations of phenol and indol derivatives has featured theoretical investigation of the charge-transfer complexes formed between carbanions and molecular oxygen (organodioxide anions).20... 

Najafpour MM, Ehrenberg T, Wiechen M, Kurz P. Calcium manganese(III) oxides (CaMn204 x H20) as biomimetic oxygen-evolving catalysts. Angew Chem Int Ed. 2010 49(12) 2233-7. 

The possibility that an electron-transfer path is involved in photo-sensitized oxygenation has been considered on several occasions. This is relevant in several fields of application, from the biomimetic oxygenation of indole and flavin derivatives [106] to pollutant control. With reference to latter, it has been suggested that SET occurs in heterogeneous photosensitized oxidation by solid semiconductors, in which the adsorbed substrate donates an electron to the photogenerated hole and... 

McLain, J., X Lee, and XT. Groves (1999). Biomimetic oxygenations related to cytochrome P450 Metal-oxo and metal-peroxo intermediates. In B. Meunier (ed.), Biomimetic Oxidations. ICP Publishers, pp. 91-170. 

P-lO - Biomimetic oxygen transfer by Co and Cu complexes immobilized in porous matrices... 

Various oxidations with [bis(acyloxy)iodo]arenes are also effectively catalyzed by transition metal salts and complexes [726]. (Diacetoxyiodo)benzene is occasionally used instead of iodosylbenzene as the terminal oxidant in biomimetic oxygenations catalyzed by metalloporphyrins and other transition metal complexes [727-729]. Primary and secondary alcohols can be selectively oxidized to the corresponding carbonyl compounds by PhI(OAc)2 in the presence of transition metal catalysts, such as RuCls [730-732], Ru(Pybox)(Pydic) complex [733], polymer-micelle incarcerated ruthenium catalysts [734], chiral-Mn(salen)-complexes [735,736], Mn(TPP)CN/Im catalytic system [737] and (salen)Cr(III) complexes [738]. The epox-idation of alkenes, such as stilbenes, indene and 1-methylcyclohexene, using (diacetoxyiodo)benzene in the presence of chiral binaphthyl ruthenium(III) catalysts (5 mol%) has also been reported however, the enantioselectivity of this reaction was low (4% ee) [739]. 

The biomimetic oxygenation of indoles, e. g. (20), induced by Co(II)salen probably involves the initial formation of the Co(III) derivative (21) as an obligatory intermediate. Oxygenation at C-3 affords (22) which cleaves its C-2, C-3 bond to give (23) (Scheme 15) 11). 

A new field of application is the use of zeolites as templates for generating supramolecular solid materials, e.g. as biomimetic oxygen carriers [14] or photosynthetic systems [15]. The pore structure controls the access of substrates to the active sites closely related to... 

One-step hydroxylation of aromatic nucleus with nitrous oxide (N2O) is among recently discovered organic reactions. A high eflSciency of FeZSM-5 zeolites in this reaction relates to a pronounced biomimetic-type activity of iron complexes stabilized in ZSM-5 matrix. N2O decomposition on these complexes produces particular atomic oj gen form (a-oxygen), whose chemistry is similar to that performed by the active oxygen of enzyme monooxygenases. Room temperature oxidation reactions of a-oxygen as well as the data on the kinetic isotope effect and Moessbauer spectroscopy show FeZSM-5 zeolite to be a successfiil biomimetic model. 

Results discussed above show in several lines a distinct biomimetic-type activity of iron complexes stabilized in the ZSM-S matrix. The most important feature is their unique ability to coordinate a very reactive a-oxygen form which is similar to the active oxygen species of MMO. At room temperature a-oxygen provides various oxidation reactions including selective hydroxylation of methane to methanol. Like in biological oxidation, the rate determining step of this reaction involves the cleavage of C-H bond. 

Both mechanisms can also rationalize an increase in due to the production of superoxide/HO2 (18.16), which appears to dominate the flux of partially reduced oxygen species generated by certain biomimetic catalysts [Boulatov et al., 2002 Boulatov, 2004]. It remains to be estabhshed if either of these two mechanisms does indeed operate in simple Fe porph5Tins, for example by carrying out single-turnover experiments similarly to the approach used to study ORR by C5hochrome c oxidase. 

In contrast to simple metalloporphyrins, or cofacial diporphyrins, the catalytic performance of these biomimetic catalysts improves at higher pH as a result, the smallest overpotential was observed at pH 8 (0.5 V) and at pH > 8 no partially reduced oxygen species could be detected at any potential. 

Boulatov R. 2006. Billion-years old oxygen cathode that actually works Respiratory oxygen reduction and its biomimetic analogs. In Zagal JH, Bedioui F, Dodelet J-P, editors. N4-Macrocyclic Metal Complexes. New York Springer, p. 1. 

CoSalen Y carries oxygen as a cargo.72 The catalytic properties of the zeolite-encapsulated metal complexes depend mainly on the complexed metal atoms, which are used usually as oxidation catalysts but other applications are also beginning to emerge. The zeolite-encapsulated catalysts can be regarded as biomimetic oxidation catalysts.73 In liquid-phase oxidation reactions catalyzed... 

Vassilikogiannakis and coworkers described a simple sequential process for the biomimetic synthesis of litseaverticillol B (4-159) which includes a cycloaddition of 4-158 and singlet oxygen to give 4-160, followed by ring opening to afford the hydro-genperoxide 4-161 (Scheme 4.34) [55]. Reduction of 4-161 led to the hemiacetal 4-162, which underwent an aldol reaction to afford 4-159. 

A mild aerobic palladium-catalyzed 1,4-diacetoxylation of conjugated dienes has been developed and is based on a multistep electron transfer46. The hydroquinone produced in each cycle of the palladium-catalyzed oxidation is reoxidized by air or molecular oxygen. The latter reoxidation requires a metal macrocycle as catalyst. In the aerobic process there are no side products formed except water, and the stoichiometry of the reaction is given in equation 19. Thus 1,3-cyclohexadiene is oxidized by molecular oxygen to diacetate 39 with the aid of the triple catalytic system Pd(II)—BQ—MLm where MLm is a metal macrocyclic complex such as cobalt tetraphenylporphyrin (Co(TPP)), cobalt salophen (Co(Salophen) or iron phthalocyanine (Fe(Pc)). The principle of this biomimetic aerobic oxidation is outlined in Scheme 8. 

Fig. 3.3 The myoglobin biomimetic molecule Fe(TpivPP)(2-Melm)(02), known as picket-fence-oxygen [18d]. 

The Picket-fence-oxygen Biomimetic Complex 3.3.2.1 Interplay Structure/Electronic State... 

Biorefineries New catalytic pretreatment of plant materials Valorization, pretreatment or disposal of co-products and wastes from biorefinery by catalytic treatments New and/or improved catalytic processes for chemicals production through the integration of the biorefinery concept and products into the existing chemical production chain New advanced catalytic solutions to reduce waste emissions (solid, air and, especially, water) New catalysts to selectively de-oxygenate products from biomass transformation Catalysts to selectively convert chemicals in complex multicomponent feedstocks New biomimetic catalysts able to operate under mild conditions Small catalytic pyrolysis process to produce stabilized oil for further processing in larger plants... 

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