空气条件下温和高效催化N-吡啶吲哚啉的氧化脱氢

报道了空气条件下温和高效的N-羟基邻苯二甲酰亚胺和铜共同催化N-吡啶吲哚啉的氧化脱氢反应.己知的N-吡啶吲哚啉的氧化过程只能在过量强氧化剂2,3-二氯-5,6-二.氰对苯醌存在下实现,该反应以空气作为单一的氧化剂具有绿色、安全、低成本以及操作简便等优点,为N-吡啶吲哚啉类化合物氧化生成相应吲哚衍生物提供了一条新的绿色途...     

FeIII and FeII Phosphasalen Complexes: Synthesis,Characterization, and Catalytic Application for 2-Naphthol Oxidative Coupling

We report on the synthesis and characterization of three iron(III) phosphasalen complexes, [Fe^III(Psalen)(X)] differing in the nature of the counter-anion/exogenous ligand (X⁻=Cl⁻, NO₃⁻, OTf⁻), as well as the neutral iron(II) analogue, [Fe^II(Psalen)] . Phosphasalen (Psalen) differs from salen by the presence of iminophosphorane (P=N) functions in place of the imines. All the complexes were characterized by single-crystal X-ray diffraction, UV/Vis, EPR, and cyclic voltammetry. The [Fe^II(Psalen)] complex was shown to remain tetracoordinated even in coordinating solvent but surprisingly exhibits a magnetic moment in line with a Fe^II high-spin ground state. For the Fe^III complexes, the higher lability of triflate anion compared to nitrate was demonstrated. As they exhibit lower reduction potentials compared to their salen analogues, these complexes were tested for the coupling of 2-naphthol using O₂ from air as oxidant. In order to shed light on this reaction, the interaction between 2-naphthol and the Fe^III(Psalen) complexes was studied by cyclic voltammetry as well as UV/Vis spectroscopy.     

Efficient Catalytic Synthesis of Condensed Isoxazole Derivatives via Intramolecular Oxidative Cycloaddition of Aldoximes

The intramolecular oxidative cycloaddition reaction of alkyne- or alkene-tethered aldoximes was catalyzed efficiently by hypervalent iodine(III) species to afford the corresponding polycyclic isoxazole derivatives in up to a 94% yield. The structure of the prepared products was confirmed by various methods, including X-ray crystallography. Mechanistic study demonstrated the crucial role of hydroxy(aryl)iodonium tosylate as a precatalyst, which is generated from 2-iodobenzoic acid and m-chloroperoxybenzoic acid in the presence of a catalytic amount of p-toluenesulfonic acid.     

Palladium/Imidazolium Salts: A General and Highly Efficient Catalytic System for Coupling Reaction

Nucleophilic N-heterocyclic carbenes have attracted considerable attention. These ligands are strong σ-donor with negligible π-accepting ability, and in this regard, they resemble electron-donor phosphines and can be addressed as "phosphine mimics". [ 1]     

The Catalytic Oxidative Coupling of Methane

One of the great challenges in the field of heterogeneous catalysis is the conversion of methane to more useful chemicals and fuels. A chemical of particular importance is ethene, which can be obtained by the oxidative coupling of methane. In this reaction CH₄ is first oxidatively converted into C₂H₆, and then into C₂H₄. The fundamental aspects of the problem involve both a heterogeneous component, which includes the activation of CH₄ on a metal oxide surface, and a homogeneous gas-phase component, which includes free-radical chemistry. Ethane is produced mainly by the coupling of the surface-generated CH radicals in the gas phase. The yield of C₂H₄ and C₂H₆ is limited by secondary reactions of CH radicals with the surface and by the further oxidation of C₂H₄, both on the catalyst surface and in the gas phase. Currently, the best catalysts provide 20% CH₄ conversion with 80% combined C₂H₄ and C₂H₆ selectivity in a single pass through the reactor. Less is known about the nature of the active centers than about the reaction mechanism; however, reactive oxygen ions are apparently required for the activation of CH₄ on certain catalysts. There is spectroscopic evidence for surface O^? or O ions. In addition to the oxidative coupling of CH₄, cross-coupling reactions, such as between methane and toluene to produce styrene, have been investigated. Many of the same catalysts are effective, and the cross-coupling reaction also appears to involve surface-generated radicals. Although a technological process has not been developed, extensive research has resulted in a reasonable understanding of the elementary reactions that occur during the oxidative coupling of methane.     

A Porphyrin-Based Covalent Organic Framework for Metal-Free Photocatalytic Aerobic Oxidative Coupling of Amines

Imines are important intermediates in drug synthesis. Photocatalytic aerobic oxidative coupling of amines has been considered as a clean and promising way to produce imines and has attracted great attention. Herein, we designed and synthesized a novel two-dimensional porphyrin-based covalent organic framework (Por-BC-COF) which adopts an AA stacking mode with excellent crystallinity, high Brunauer–Emmett–Teller surface areas (1200 m² g⁻¹), wide light absorption range (200–1300 nm) and good stability in a variety of organic solvents. Por-BC-COF can be used as a metal-free heterogeneous photocatalyst for the photocatalytic oxidation of amines to imines under visible light and red light with a high yield (97 %). This work presents a novel and efficient COF photocatalyst in the application of light-driven organic synthesis.     

An Efficient Mg/SmI_2 Catalytic System for the Intermolecular Deoxygenative Coupling of Amides and Ketones

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An Efficient Mg/Sml2 Catalytic System for the Intermolecular Deoxygenative Coupling of Amides and Ketones

The intermolecular deoxygenative coupling of ketones with amides induced by Mg/Sml₂ catalyst was studied and a series of enamines was synthesized in moderate yields under mild and neutral conditions.     

A Facile Procedure for the oxidative Coupling of 2-Naphthol and 2-Naphthalenethiol in Solid State

l,lLBi-2-naPhtholshavebeenwidelyappliedasimportantchiralauxiliariesandligands..tinorganicchemistry'.TheconversionofthiolstothecorrespondingdisulphidesisofintCrestbothfromabiological'andpracticalpointofview.ForthesynthesisofbinaPhtholsanddisulphides,theoxidativecouplingofnaphtholsandthiolshaslongbeenarecognisedmethodofchoice.Variousoxidantscanbringaboutthecouplingofnaphthols'andthiols4insolution,buttheyoftenleadtolowyieldsorsufferfromdisadvantagesduetotheinsolubilityofoxidant,naPhthoIandthiol…     

Auto‐Oxidative Coupling of Glycine Derivatives

The unprecedented title reaction between glycine derivatives and indoles, as well as the auto‐oxidative Povarov/aromatization tandem reaction of glycine derivatives with olefins are described. The reactions were performed in the absence of redox‐active catalysts and chemical oxidants under mild reaction conditions. Only simple organic solvents and air (or O₂) were required.     

Novel and Efficient Synthesis of Pyrimidine Derivatives

A new series of 1-alkyl-2-oxo-1,2-dihydro-pyrimidine-5-carboxalic acid amides is described. The reaction of N-((E)-3-(dimethylamino)-2-formylacryloyl) formamidine, an intermediate obtained by Vilsmeier–Haack formylation of acetonitrile with various mono-substituted ureas, provides such compounds in good yields.     

芳香化合物直接催化氧化偶联反应研究进展

总结了近年来非官能化芳香化合物直接催化氧化偶联合成联芳香化合物的研究进展,包括芳香化合物的自身偶联、交叉偶联以及分子内偶联反应,同时对反应中涉及的机理也进行了详细地讨论.     

一种新的催化方法：微波辐射-酶耦合成催化有机合成

微波辐射和酶催化是现代有机合成化学中两种强有力的催化手段。目前一种新 的研究动向是将两者结合起来用于催化有机合成反应,这种新型催化方法可以被称 作微波辐射-酶耦合催化（MIECC）。由MIECC方法催化的有机合成反应可以被分为 湿法和干法两大类型。介绍了这一新型耦合催化方法的研究进展以及一些典型 MIECC反应。对MIECC反应中可能存在的耦合催化机理,即微波在生物催化体系中的 “非热效应“进行了初步理论探讨,同时展望了这种新的耦合催化方法的前景。     

Discovery of a Metalloenzyme-like Cooperative Catalytic System of Metal Nanoclusters and Catechol Derivatives for the Aerobic Oxidation of Amines

We have discovered a new class of cooperative catalytic system, consisting of heterogeneous polymer-immobilized bimetallic Pt/Ir alloyed nanoclusters (NCs) and 4-tert-butylcatechol, for the aerobic oxidation of amines to imines under ambient conditions. After optimization, the desired imines were obtained in good to excellent yields with broad substrate scope. The reaction rate was determined to be first-order with respect to the substrate and catechol and zero-order for the alloyed Pt/Ir NC catalyst. Control studies revealed that both the heterogeneous NC catalyst and 4-tert-butylcatechol are essential and act cooperatively to facilitate the aerobic oxidation under mild conditions.     

Efficient Catalytic and Thermal Syntheses of Novel Thiadiazole,Triazole, Benzothiazole,and Fused Quinazoline Derivatives

Russian Journal of Organic Chemistry - A thiourea derivative, 4-chloro-N-[(4-chlorophenyl)carbamothioyl]benzamide, was oxidized with iodine in acetic acid to give the corresponding disulfide,...     

碱土—稀土氧化物在甲烷偶联反应中的催化性能

研究了两个典型轻稀土Ｌａ，Ｃｅ氧化物对甲烷氧化联反应的影响，具有较小比表面积的催化给出较高的Ｃ２选择性，但是催化剂的氧化还原性能对Ｃ２选择性的影响则更大，添加Ｌｉ的作用除产生Ｏ中心外，还可抑制催化剂的氧化还原能力，从而改善Ｃ２选择性，甲烷氧化偶联反应属催化剂引发的自由基反应。     

碱土－稀土氧化物在甲烷偶联反应中的催化性能

研究了两个典型轻稀土Ｌａ，Ｃｅ氧化物对甲烷氧化偶联反应的影响，具有较小比表面积的催化剂给出较高的Ｃ＿２选择性，但是催化剂的氧化还原性能对Ｃ＿２选择性的影响则更大，添加Ｌｉ的作用除产生Ｏ￣－中心外，还可抑制催化剂的氧化还原能力，从而改善Ｃ＿２选择性。甲烷氧化偶联反应属催化剂引发的自由基反应。     

1,1′-联萘化合物的氧化偶联合成

评述了β-萘酚序列化合物在铜胺络合物、硫酸铜、铁盐、氧钒络合物等作用下,直接氧化偶联合成1,1′-联萘化合物的路线,讨论了反应机理.