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1.
The direct addition of a variety of alcohols to in situ activated olefins was observed in the presence of mild bifunctional amine/acid catalysts. Unlike existing methods, the reactions proceed at room temperature and in the absence of transition metals. The use of simple commercially available catalysts, amines and acids makes this an attractive method for the preparation of β-alkoxy ketones, which are prevalent targets and intermediates in organic synthesis. 相似文献
2.
Isabel W. C. E. Arends Roger A. Sheldon Martin Wallau Ulf Schuchardt 《Angewandte Chemie (International ed. in English)》1997,36(11):1144-1163
Zeolites are viewed by some as the “philosopher's stone” of modern chemistry.[1] They are more or less indispensable in oil refining and petrochemicals manufacture where they are widely applied as solid acid catalysts. More recently attention has been focused on their use in the manufacture of fine chemicals. The synthetic utility of zeolites and related molecular sieves (zeotypes) has been considerably extended by the incorporation of redox metals into their frameworks. The resulting redox molecular sieves catalyze a variety of selective oxidations under mild conditions in the liquid phase. Their structural diversity–including variation of the redox metal, incorporation of metal complexes, and the size and polarity of the micropores–provides the possibility of designing tailor-made solid catalysts (“mineral enzymes”) for liquid-phase oxidations with clean oxidants such as O2, H2O2, and RO2H. Hence, they have enormous potential in industrial organic synthesis as environmentally friendly alternatives to traditional oxidations employing inorganic oxidants in stoichiometric amounts. A primary aim of this review is to familiarize organic chemists with the synthetic potential of redox molecular sieves. An outline of their synthesis, structures, and chemical properties, highlighting their unique advantages, is followed by a discussion of general (mechanistic) features that influence the choice of a suitable catalyst for a particular type of oxidation. The main part of the review deals with the oxidation of various substrates of synthetic interest–such as alkanes, alkenes, (alkyl)arenes, alcohols, and amines–and emphasizes the advantages of redox molecular sieves (including selectivity and stability) over their homogeneous counterparts. New directions towards truly biomimetic solid catalysts, for example zeolite-encapsulated chiral metal complexes as heterogeneous catalysts for asymmetric oxidations, are high-lighted. 相似文献
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Simulation of the function of cytochrome P-450 with low valent ruthenium complex catalysts leads to the discovery of biomimetic, catalytic oxidation of various substrates selectively under mild conditions. The reactions discussed in this tutorial review are simple, clean, and practical. The principle of these reactions is fundamental and gives wide-scope and environmentally benign future practical methods. 相似文献
5.
在生命体中,细胞色素P-450单充氧酶辅基是具有铁Df琳结构的血红素.用金属叶琳作为细胞色素P-450单充氧酶的模型化合物探讨和研究人类生命现象一直是国内外化学仿生催化领域极为感兴趣的研究内容之一[’1.我们曾用p一氧代双铁叶琳作为细胞色素P-450单充氧酶的模型化合物,发现改变金属叶琳结构和金属原子电子自旋态将会引起金属叶琳磁性改变,而金属叶琳磁性改变会进一步导致金属叶琳仿生催化性能发生改变D”‘.我们认为,这一现象与人类和地球构成的生物圈可能有某些关联.为了考察地球磁场对人类生命现象的影响,我们进一步建立… 相似文献
6.
Largeron M Chiaroni A Fleury MB 《Chemistry (Weinheim an der Bergstrasse, Germany)》2008,14(3):996-1003
Environmentally friendly oxidation of primary aliphatic amines to imines has been successfully achieved, under metal-free conditions, by the use of diverse electrogenerated o-azaquinone mediators. High catalytic performance, together with high chemoselectivity, were observed with electron-poor o-azaquinone catalysts generated from 2-aminoresorcinol derivatives. Similar to copper amine oxidase enzymes, these mediators exhibited lower reactivity toward alpha-branched primary amines and no reactivity toward secondary amines. In the case of 3,4-aminophenol derivatives lacking a 2-hydroxy group, the generated o-azaquinone species failed to catalyze the oxidation of the amine to the corresponding imine. Further mechanistic considerations allowed a rationalization of the crucial role of the 2-hydroxy group in converting a catalytically inert species into a highly effective biomimetic catalyst. 相似文献
7.
《应用有机金属化学》2017,31(3)
Schiff bases and their complexes are good candidates as versatile compounds which are synthesized by the condensation of a primary amino compound with either aldehydes or ketones for a variety of industrial applications. They can act as catalysts in the catalytic oxidation of organic compounds. Recent researches in oxidation catalysis have focused on how to employ the metal‐catalyzed oxidation of organic substrates. This review summarizes the current developments of the last few decades for the oxidations of organic compounds that proceed through Schiff base complexes. The chemical syntheses of Schiff bases and their complexes are outlined. 相似文献
8.
Enzymatic hydroxylations with molecular oxygen 总被引:1,自引:0,他引:1
V Ullrich 《Angewandte Chemie (International ed. in English)》1972,11(8):701-712
For thermodynamic reasons, biological hydroxylations cannot usually proceed according to the β-oxidation scheme, but are possible only with the aid of molecular oxygen by a route requiring a large amount of energy. The corresponding enzymes, known as “mixed function oxygenases” or more appropriately “monooxygenases”, require two reduction equivalents for the activation of oxygen. The cytochrome P-450-dependent monooxygenases are taken as examples for the discussion of the chemistry of the enzymatic catalysis. The central problem of the activation of oxygen has not yet been solved, but an “oxenoid” mechanism can be deduced from model investigations. 相似文献
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Jurva U Wikström HV Weidolf L Bruins AP 《Rapid communications in mass spectrometry : RCM》2003,17(8):800-810
The extent to which electrochemistry on-line with electrospray mass spectrometry can be used to mimic cytochrome P450 catalyzed oxidations has been investigated. Comparisons on the mechanistic level have been made for most reactions in an effort to explain why certain reactions can, and some cannot, be mimicked by electrochemical oxidations. The EC/MS/MS system used successfully mimics in cases where the P450 catalyzed reactions are supposed to proceed via a mechanism initiated by a one-electron oxidation, such as N-dealkylation, S-oxidation, P-oxidation, alcohol oxidation and dehydrogenation. The P450 catalyzed reactions initiated via direct hydrogen atom abstraction, such as O-dealkylation and hydroxylation of unsubstituted aromatic rings, generally had a too high oxidation potential to be electrochemically oxidized below the oxidation potential limit of water, and were not mimicked by the EC/MS/MS system. Even though the EC/MS/MS system is not able to mimic all oxidations performed by cytochrome P450, valuable information can be obtained concerning the sensitivity of the substrate towards oxidation and in which position of the molecule oxidations are likely to take place. For small-scale electrochemical synthesis of metabolites, starting from the drug, the EC/MS/MS system should be very useful for quick optimization of the electrochemical conditions. The simplicity of the system, and the ease and speed with which it can be applied to a large number of compounds, make it a useful tool in drug metabolism research. 相似文献
11.
Dr. Alexander Yu. Rulev 《European journal of organic chemistry》2023,26(26):e202300451
The 1,4-conjugated addition of nitrogen centered nucleophiles to electron-deficient alkenes, historically called the aza-Michael addition, is one of the most significant and widely used reactions in modern synthetic organic chemistry. In the last decade, great progress has been made in this field namely in the development of various catalytic systems. Fundamental advances involve the use of transition metal catalysts, organocatalysts, enzymes, ionic liquids, Brønsted and Lewis acids and bases. This Review aims to critically analyze the results of research into the reactions of aliphatic and aromatic amines with Michael acceptors. 相似文献
12.
Bui Dinh Nhi Dr. Renat Maratovich Akhmadullin Dr. Alfiya Garipovna Akhmadullina Dr. Yakov Dmitrievich Samuilov Dr. Svetlana Ivanova Aghajanian 《Chemphyschem》2013,14(18):4149-4157
We investigate the physicomechanical properties of polymeric heterogeneous catalysts of transition‐metal oxides, specifically, the specific surface area, elongation at break, breaking strength, specific electrical resistance, and volume resistivity. Digital microscopy, Fourier‐transform infrared spectroscopy, X‐ray diffraction, scanning electron microscopy, and energy‐dispersive analysis are used to study the surfaces of the catalysts. The experimental results show that polymeric heterogeneous catalysts of transition‐metal oxides exhibit high stability and can maintain their catalytic activity under extreme reaction conditions for long‐term use. The oxidation mechanism of sulfur‐containing compounds in the presence of polymeric heterogeneous catalysts of transition‐metal oxides is confirmed. Microstructural characterization of the catalysts is performed by using X‐ray computed tomography. The activity of various catalysts in the oxidation of sulfur‐containing compounds is determined. We demonstrate the potential application of polymeric heterogeneous catalysts of transition‐metal oxides in industrial wastewater treatment. 相似文献
13.
Inspired by quinone-redox enzymes, small molecular quinone catalysts have been developed to promote C-H functionalization of amines. Recent efforts in this area have been summarized. 相似文献
14.
Simple Copper Catalysts for the Aerobic Oxidation of Amines: Selectivity Control by the Counterion
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Boran Xu Elizabeth M. Hartigan Giancarlo Feula Zheng Huang Prof. Jean‐Philip Lumb Prof. Bruce A. Arndtsen 《Angewandte Chemie (International ed. in English)》2016,55(51):15802-15806
We describe the use of simple copper‐salt catalysts in the selective aerobic oxidation of amines to nitriles or imines. These catalysts are marked by their exceptional efficiency, operate at ambient temperature and pressure, and allow the oxidation of amines without expensive ligands or additives. This study highlights the significant role counterions can play in controlling selectivity in catalytic aerobic oxidations. 相似文献
15.
N. Padmanabha Iyer T. Philip Gnanarajan Ganga Radhakrishnan 《Journal of polymer science. Part A, Polymer chemistry》2001,39(24):4236-4242
The catalysis of imidine formation between an amine‐blocked polyurethane prepolymer and bisphthalide was studied with a series of metal alkoxides, phenoxides, and organotin compounds and tertiary amines. The carbon dioxide released during the reaction was followed for monitoring of the reaction. The metal alkoxides and phenoxides catalyzed the imidine formation reaction but did not catalyze the deblocking reaction, whereas the organotin compounds and tertiary amines showed no catalytic activity in the reaction between isocyanate and phthalide. With tin catalysts, the imidine formation reaction depended on the deblocking of the blocked prepolymer, but it was independent of deblocking with amine catalysts. The resultant poly(urethane imidine) copolymers were characterized with Fourier transform infrared, 1H NMR, 13C NMR, gel permeation chromatography, and thermogravimetric analysis techniques. The thermal stability of polyurethane increased significantly with the incorporation of imidine groups. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 4236–4242, 2001 相似文献
16.
By virtue of its ability to generate hydrated electrons (eaq ?) and various radicals as reductants, the pulse radiolysis technique has been employed for investigating the mechanism of action of peroxidase, cytochrome P-450, and cytochrome oxidase. The oxy forms of hemoproteins, such as myoglobin, peroxidase, and cytochrome P-450, were reduced by hydrated electrons to form the higher oxidation states of these hemoproteins. From these results, the reactive oxygen intermediate of cytochrome chrome P-450 is discussed. The reduction of cytochrome oxidase by the 1-methylnicotinamide radical was investigated. A decrease of the 830-nm band was detected due to the reduction of “visible” copper. After the first phase of the reduction of copper, the return of the 830-nm band corresponding to oxidation of copper was observed. Concomitantly, the absorption at 605 and 445 nm due to the reduction of heme α increased. This suggests that 1-methylnicotinamide radical reacts with the “visible” copper and subsequently flows to heme α by intramolecular migration. 相似文献
17.
Ye Wang 《Research on Chemical Intermediates》2006,32(3):235-251
Recent studies on iron-based heterogeneous catalysts for selective oxidation of hydrocarbons are reviewed with emphasis on
the partial oxidation of methane and the epoxidation of alkenes. High dispersion of iron sites is essentially important for
the selective oxidations. The effective catalysts include immobilized or encapsulated iron complexes, iron-doped metal oxides
such as Fe3+-doped silica, iron-containing microporous and mesoporous materials, and iron-containing compounds with isolated iron sites
typified by iron phosphate. The structure-reactivity relationships and the factors affecting the catalytic performances are
discussed with the aim to uncover the requirements of the active iron sites in target-selective oxidation. 相似文献
18.
Kyle M. Lambert Prof. Dr. James M. Bobbitt Sherif A. Eldirany Liam E. Kissane Rose K. Sheridan Zachary D. Stempel Francis H. Sternberg Prof. Dr. William F. Bailey 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(15):5156-5159
Synergism among several intertwined catalytic cycles allows for selective, room temperature oxidation of primary amines to the corresponding nitriles in 85–98 % isolated yield. This metal‐free, scalable, operationally simple method employs a catalytic quantity of 4‐acetamido‐TEMPO (ACT; TEMPO=2,2,6,6‐tetramethylpiperidine N‐oxide) radical and the inexpensive, environmentally benign triple salt oxone as the terminal oxidant under mild conditions. Simple filtration of the reaction mixture through silica gel affords pure nitrile products. 相似文献
19.
Ye Wang 《Research on Chemical Intermediates》2006,32(3-4):235-251
Recent studies on iron-based heterogeneous catalysts for selective oxidation of hydrocarbons are reviewed with emphasis on the partial oxidation of methane and the epoxidation of alkenes. High dispersion of iron sites is essentially important for the selective oxidations. The effective catalysts include immobilized or encapsulated iron complexes, iron-doped metal oxides such as Fe3+-doped silica, iron-containing microporous and mesoporous materials, and iron-containing compounds with isolated iron sites typified by iron phosphate. The structure-reactivity relationships and the factors affecting the catalytic performances are discussed with the aim to uncover the requirements of the active iron sites in target-selective oxidation. 相似文献
20.
Drug Oxidation by Cytochrome P450BM3: Metabolite Synthesis and Discovering New P450 Reaction Types
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Xinkun Ren Dr. Jake A. Yorke Emily Taylor Ting Zhang Prof. Weihong Zhou Prof. Luet Lok Wong 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(42):15039-15047
There is intense interest in late‐stage catalytic C?H bond functionalization as an integral part of synthesis. Effective catalysts must have a broad substrate range and tolerate diverse functional groups. Drug molecules provide a good test of these attributes of a catalyst. A library of P450BM3 mutants developed from four base mutants with high activity for hydrocarbon oxidation produced human metabolites of a panel of drugs that included neutral (chlorzoxazone, testosterone), cationic (amitriptyline, lidocaine) and anionic (diclofenac, naproxen) compounds. No single mutant was active for all the tested drugs but multiple variants in the library showed high activity with each compound. The high conversions enabled full product characterization that led to the discovery of the new P450 reaction type of oxidative decarboxylation of an α‐hydroxy carboxylic acid and the formation a protected imine from an amine, offering a novel route to α‐functionalization of amines. The substrate range and varied product profiles suggest that this library of enzymes is a good basis for developing late‐stage C?H activation catalysts. 相似文献