- Visible light-driven cross-coupling reactions at lower temperatures using a photocatalyst of palladium and gold alloy nanoparticles
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Palladium (Pd)-catalyzed cross-coupling reactions are among the most important methods in organic synthesis. We report the discovery of highly efficient and green photocatalytic processes by which cross-coupling reactions, including Sonogashira, Stille, Hiyama, Ullmann, and Buchwald-Hartwig reactions, can be driven with visible light at temperatures slightly above room temperature using alloy nanoparticles of gold and Pd on zirconium oxide, thus achieving high yields. The alloy nanoparticles absorb visible light, and their conduction electrons gain energy, which is available at the surface Pd sites. Results of the density functional theory calculations indicate that transfer of the light excited electrons from the nanoparticle surface to the reactant molecules adsorbed on the nanoparticle surface activates the reactants. When the light intensity was increased, a higher reaction rate was observed, because of the increased population of photoexcited electrons. The irradiation wavelength also has an important impact on the reaction rates. Ultraviolet irradiation can drive some reactions with the chlorobenzene substrate, while visible light irradiation failed to, and substantially improve the yields of the reactions with the bromobenzene substrate. The discovery reveals the possibility of using low-energy and -density sources such as sunlight to drive chemical transformations.
- Xiao, Qi,Sarina, Sarina,Bo, Arixin,Jia, Jianfeng,Liu, Hongwei,Arnold, Dennis P.,Huang, Yiming,Wu, Haishun,Zhu, Huaiyong
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- Cu(I)-mediated reductive amination of boronic acids with nitroso aromatics.
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[reaction: see text] A mild method for the reductive amination of aryl boronic acids with nitroso aromatic compounds is reported. This C-N bond formation is mediated by a stoichiometric amount of CuCl as both a catalyst and a reducing agent. Alternatively, 10% Cu(I)-3-methylsalicylate (CuMeSal) catalyzes the same reaction in the presence of either ascorbic acid or hydroquinone as the terminal reducing agent. Diarylamines bearing a variety of functional groups can be obtained in good yields.
- Yu, Ying,Srogl, Jiri,Liebeskind, Lanny S
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- Palladium-catalyzed one-pot diarylamine formation from nitroarenes and cyclohexanones
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The first palladium-catalyzed diarylamine formation from nitroarenes and cyclohexanone derivatives using borrowed hydrogen is described. Various diarylamines were selectively obtained in good to excellent yields. The reaction tolerated a wide range of functionalities. The nitro reduction, cyclohexanone dehydrogenation, and imine formation and reduction were realized in a cascade without an external reducing reagent and oxidant.
- Xie, Yanjun,Liu, Saiwen,Liu, Yong,Wen, Yuqing,Deng, Guo-Jun
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- Intramolecular Charge Transfer Controls Switching Between Room Temperature Phosphorescence and Thermally Activated Delayed Fluorescence
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Chemical modification of phenothiazine-benzophenone derivatives tunes the emission behavior from triplet states by selecting the geometry of the intramolecular charge transfer (ICT) state. A fundamental principle of planar ICT (PICT) and twisted ICT (TICT
- Chen, Chengjian,Huang, Rongjuan,Batsanov, Andrei S.,Pander, Piotr,Hsu, Yu-Ting,Chi, Zhenguo,Dias, Fernando B.,Bryce, Martin R.
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- Enolizable Ketones as Activators of Palladium(II) Precatalysts in Amine Arylation Reactions
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Enolizable ketones have been identified as effective activators for palladium(II) precatalysts in the coupling of aryl bromides and aniline. N-arylation reactions catalyzed by [(DTBNpP)PdCl2]2 (DTBNpP = (bis(tert-butyl)neopentylphosphine) and PEPPSI-IPr precatalysts are activated by the addition of acetone, mesityl oxide, and 3-pentanone. 3-Pentanone was the most effective activator. Mechanistic studies show that acetone, 3-pentanone, and mesityl oxide reduce [(DTBNpP)PdCl2]2 in the presence of NaO-t-Bu to Pd0(DTBNpP)2
- Hu, Huaiyuan,Gilliam, Ashley M.,Qu, Fengrui,Shaughnessy, Kevin H.
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- Aromatic N-Substitution by Phenylnitrenium Ion. Reactions of Phenyl Azide with Aromatics in the Presence of Trifluoroacetic Acid
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Reactions of phenyl azide with aromatics in the presence of trifluoroacetic acid gave diarylamines by an electrophilic N-substitution of the phenylnitrenium ion onto aromatics.
- Takeuchi, Hiroshi,Takano, Katsuyuki,Koyama, Kikuhiko
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- Pentavalent organoantimony compounds as mild N-arylating agents for amines: Cu-mediated ullmann-type N-arylation with tetraarylantimony(V) acetates
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Simple and mild Cu-mediated arylation of various amines by use of tetraarylantimony acetate (Ar4SbOAc) is described. The Ullmann-type condensation of Ar4SbOAc with aliphatic and electron rich aromatic amines proceeded efficiently in
- Qin, Weiwei,Kakusawa, Naoki,Wu, Yichen,Yasuike, Shuji,Kurita, Jyoji
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- Earth abundant metal complexes of donor functionalised N-heterocyclic carbene ligands: synthesis, characterisation and application as amination catalysts
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Six new imidazolium salts of the form 3-R-1-picolylimidazolium bromide (1a: R = 4-nitrophenyl, 1b: R = 4-acetylphenyl, 1c: R = 4-cyanophenyl, 1d: R = allyl, 1e: R = butenyl, 1f: R = pentenyl) were synthesised and isolated in high yields. The corresponding Ag-NHC intermediate complexes 2a, 2d, and 2e were transmetalated to yield [M(NHC)2Cl2 M = Co, Ni] complexes in good to excellent yields. The Co-NHC (3a, 3d, 3e) and Ni-NHC (3a′, 3d′, 3e′) complexes were relatively stable in air, insoluble in chlorinated solvents but very soluble in methanol and DMSO. Poorly resolved NMR spectra and magnetic susceptibility values of 2.53 and 2.73 μB for 3d and 3e respectively suggest both to be paramagnetic cobalt complexes. All the imidazolium salts, isolated Ag-NHC complexes and the corresponding Co and Ni-NHC complexes were characterised by spectroscopic and analytical techniques. The complexes were found to be active at low catalyst loading (1 mol%) for the C-N coupling of aniline with phenyl bromide under mild reaction conditions. In addition, the in situ generated catalyst obtained from a mixture of NiCl2/1a (1:2 molar ratio) initiated the C-N coupling of several aryl amines with substituted aryl bromides bearing a wide variety of functional groups. Good to excellent yields of the desired diaryl amine products were obtained. The yields are comparable to data obtained with palladium catalysts or to data obtained under harsher temperature conditions of Cu mediated Ullman reactions.
- Ibrahim, Halliru,Bala, Muhammad Dabai
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- 3-(Diphenylphosphino)propanoic acid: An efficient ligand for Cu-catalyzed N-arylations of indoles and aryl amines
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3-(Diphenylphosphino)propanoic acid (L2) was found to be an efficient ligand for the copper-catalyzed N-arylations of indoles and arylamines with aryl iodides, the C-N coupling reactions catalyzed by CuCl/L2 were smoothly carried out in DMSO at 120 °C and give the corresponding products with the yields of 25-98 %.
- Liu,Gu,Liu,Ma,Liu,Xie
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- Synthesis of Triarylamines via Sequential C-N Bond Formation
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A one-pot domino N-arylation protocol is described using diaryliodonium reagents under copper catalysis. The reaction uses both aryl groups of the diaryliodonium reagent to generate triarylamines starting from simple anilines, representing an atom-economical preparation of an important class of organic material building blocks.
- Modha, Sachin G.,Popescu, Mihai V.,Greaney, Michael F.
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- Stable, Well-Defined Nickel(0) Catalysts for Catalytic C-C and C-N Bond Formation
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The synthesis and catalytic activity of several classes of NHC-Ni(0) precatalysts stabilized by electron-withdrawing alkenes are described. Variations in the structure of fumarate and acrylate ligands modulate the reactivity and stability of the NHC-Ni(0) precatalysts and lead to practical and versatile catalysts for a variety of transformations. The catalytic activity and efficiency of representative members of this class of catalysts have been evaluated in reductive couplings of aldehydes and alkynes and in N-arylations of amines.
- Nett, Alex J.,Canellas, Santiago,Higuchi, Yuki,Robo, Michael T.,Kochkodan, Jeanne M.,Haynes, M. Taylor,Kampf, Jeff W.,Montgomery, John
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- [P,N]-phosphinobenzimidazole ligands in palladium-catalyzed C-N cross-coupling reactions: The effect of the N-substituent of the benzimidazole scaffold on catalyst performance
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A series of [P,N]-phosphinobenzimidazole ligands is reported in which the charge (anionic vs. neutral) and size of the N-substituent of the benzimidazole scaffold has been varied. In order to evaluate the impact of the substituent's properties on the performance of the metal in catalytic reactions, each ligand was screened for its ability to promote the cross-coupling of aryl bromides with various primary aryl amines using palladium as the metal source. In general, the ligands formed active cross-coupling catalysts with palladium. Moreover, the ligand variants containing larger N-substituents boosted the efficiency of the cross-coupling reaction considerably, while their charge (either anionic or neutral) appeared to have no significant impact.
- Tassone, Joseph P.,Spivak, Gregory J.
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- Aromatic Substitution by Phenylnitrenium and Naphthylnitrenium Ions formed from Phenyl Azide and 1-Azidonaphthalene in the Presence of Trifluoromethanesulphonic Acid
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Aromatic N-substitution by phenylnitrenium ions generated from phenyl azide in the presence of a catalytic amount of trifluoromethanesulphonic acid gave diarylamines (in especially good yield in the reaction with biphenyl or naphthalene), whereas naphthylnitrenium ions from 1-azidonaphthalene react with benzene to afford a C-substitution product, 1-amino-4-phenylnaphthalene.
- Takeuchi, Hiroshi,Takano, Katsuyuki
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- Studies on the reactivity of aryliodonium ylides of 2-hydroxy-1,4-naphthoquinone: Reactions with amines
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Aryliodonium ylides of 2-hydroxy-1,4-naphthoquinone react with amines in refluxing dichloromethane to afford good yields of indanedione 2-carboxamides 5, through a ring-contraction and α,α′-dioxoketene formation reaction. These amides exist in solution in an unusual enol-amide form. In contrast, the same reactants in a copper-catalyzed reaction afford arylamines and 3-iodo-4-hydroxy-1,2-naphthoquinone.
- Malamidou-Xenikaki, Elizabeth,Spyroudis, Spyros,Tsanakopoulou, Maria
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- High Catalytic Activity of Peptide Nanofibres Decorated with Ni and Cu Nanoparticles for the Synthesis of 5-Substituted 1H-Tetrazoles and N-Arylation of Amines
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A rapid development of a new methodology for decarboxylative N-arylation of carboxylic acids and the preparation of 5-substituted 1H-tetrazoles catalysed by peptide nanofibres decorated with Cu and Ni nanoparticles is presented. Compared with conventional aryl halides, benzoic acids are extremely interesting and environmentally friendly options for the synthesis of secondary aryl amines.
- Ghorbani-Choghamarani, Arash,Taherinia, Zahra
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- Ni(II)-(σ-aryl) complex: A facile, efficient catalyst for nickel-catalyzed carbon-nitrogen coupling reactions
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(Chemical Equation Presented) trans-Haloarylbis(triphenylphosphine) nickel(II), a type of air-and moisture-stable Ni(II)-(σ-aryl) complex, was examined as catalyst precursor in the C-N coupling reaction. This type of Ni(II) pre-catalyst, associated with N-heterocyclic carbene ligands, is found to easily produce the catalytically active Ni(0) species in situ without the aid of external reductants and allows for the efficient amination of aryl chlorides with secondary cyclic amines and anilines under mild conditions.
- Chen, Chen,Yang, Lian-Ming
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- N-Heterocyclic Carbene Palladium(II) Amine Complexes: The Role of Primary Aryl- or Alkylamine Binding and Applications in the Buchwald-Hartwig Amination Reaction
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N-heterocyclic carbene-palladium(II) amine complexes bearing primary aryl- or alkylamines were synthesized. The prepared complexes were characterized by single crystal X-ray diffraction as well as NMR spectroscopy. These complexes exhibited good catalytic activities for the Buchwald-Hartwig amination reaction of aryl chlorides to afford arylated anilines under mild conditions. All reactions were carried out in air and all starting materials were used as supplied without purification. 21 expected coupling products were obtained in moderate to high yields under optimum conditions.
- Hsu, Yu-Cheng,Chen, Ming-Tsz
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supporting information
(2021/12/24)
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- Mediator-Enabled Electrocatalysis with Ligandless Copper for Anaerobic Chan-Lam Coupling Reactions
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Simple copper salts serve as catalysts to effect C-X bond-forming reactions in some of the most utilized transformations in synthesis, including the oxidative coupling of aryl boronic acids and amines. However, these Chan-Lam coupling reactions have historically relied on chemical oxidants that limit their applicability beyond small-scale synthesis. Despite the success of replacing strong chemical oxidants with electrochemistry for a variety of metal-catalyzed processes, electrooxidative reactions with ligandless copper catalysts are plagued by slow electron-transfer kinetics, irreversible copper plating, and competitive substrate oxidation. Herein, we report the implementation of substoichiometric quantities of redox mediators to address limitations to Cu-catalyzed electrosynthesis. Mechanistic studies reveal that mediators serve multiple roles by (i) rapidly oxidizing low-valent Cu intermediates, (ii) stripping Cu metal from the cathode to regenerate the catalyst and reveal the active Pt surface for proton reduction, and (iii) providing anodic overcharge protection to prevent substrate oxidation. This strategy is applied to Chan-Lam coupling of aryl-, heteroaryl-, and alkylamines with arylboronic acids in the absence of chemical oxidants. Couplings under these electrochemical conditions occur with higher yields and shorter reaction times than conventional reactions in air and provide complementary substrate reactivity.
- Walker, Benjamin R.,Manabe, Shuhei,Brusoe, Andrew T.,Sevov, Christo S.
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supporting information
p. 6257 - 6265
(2021/05/07)
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- Chitosan nanoparticles functionalized poly-2-hydroxyaniline supported CuO nanoparticles: An efficient heterogeneous and recyclable nanocatalyst for N-arylation of amines with phenylboronic acid at ambient temperature
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The present study aims to prepare an effective and eco-friendly nanocatalyst for the Chan–Lam coupling reaction of phenylboronic acid and amine in aerobic conditions. For this purpose, chitosan was extracted from shrimp shells waste by demineralization, deproteinization, and deacetylation processes and then converted to chitosan nanoparticles (CSN) by the ionic gelation with tripolyphosphate anions. Afterward, poly-2-hydroxyaniline (P2-HA) was grafted to chitosan nanoparticles (NPs) to employ as the support for CuO NPs. Characterization of the nanocatalyst was done using Fourier transform infrared (FT-IR), X-ray powder diffraction (XRD), scanning electron microscopy (SEM), mapping, energy-dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), and thermogravimetric analysis (TGA). The CuO NPs were identified in the spherical shape with an average size of 17 nm. The prepared nanocatalyst exhibited excellent catalytic performance with a high turnover number (TON) and turnover frequency (TOF) for the Chan–Lam coupling reaction of phenyl boronic acid and amines with different electronic properties. The prepared catalyst could be readily recovered and reused for at least five runs without any noticeable change in structure and catalytic performance. Chitosan (CS) was prepared via demineralization, deproteinization, and deacetylation of shrimp shell and chitosan nanoparticles (CSN) were prepared via ionic gelation process. Polymerization of 2-HA on the CSN surface was done to increase functional groups and create active sites for CuO NPs attachments. CuO NPs-P2-HA-CSN nanocomposite has been shown high efficiently for the Chan–Lam coupling reaction.
- Seyedi, Neda,Zahedifar, Mahboobeh
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- Design of Benzimidazolyl Phosphines Bearing AlterableP,OorP,N-Coordination: Synthesis, Characterization, and Insights into Their Reactivity
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A new series of hemilabile benzimidazolyl phosphines is reported. Entities in this ligand family can be easily assembled and prepared on a large scale via a simple one-pot procedure. X-ray crystallographic analyses show that the Pd metal center can coordinate in different fashions, where it relies on the size of the ?PR2group. With the same ligand scaffold, the ligand having a ?PCy2moiety displays better efficiency in expediting aromatic C-C bond-coupling reactions, while the ligand associated with a ?P-t-Bu2group, in contrast, promotes C-N bond-forming reactions.
- Wong, Shun Man,Choy, Pui Ying,Zhao, Qingyang,Yuen, On Ying,Yeung, Chung Chiu,So, Chau Ming,Kwong, Fuk Yee
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supporting information
p. 2265 - 2271
(2021/05/05)
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- Nitrogen-containing compound, organic electroluminescent device, and electronic device
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The invention provides a nitrogen-containing compound, an organic electroluminescent device and an electronic device, and belongs to the technical field of organic materials. The structure of the nitrogen-containing compound is represented by Chemical Formula 1: wherein X1, X2, Y1, Y2 are the same or different from each other and are each independently a single bond, O, S, N(R3), C(R4R5), Ge(R6R7), Si(R8R9), Se, wherein X1 and Y1 are not single bonds simultaneously and X2 and Y2 are not single bonds simultaneously.
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Paragraph 0111-0117
(2021/01/24)
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- Diphenylamine derivative organic room-temperature phosphorescent compound as well as preparation method and application thereof
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The present invention provides a diphenylamine derivative organic room temperature phosphorescent compound, which is characterized in that the structural formula of the diphenylamine derivative organic room temperature phosphorescent compound is represent
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Paragraph 0057-0062
(2021/07/24)
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- Electrochemical Reductive Arylation of Nitroarenes with Arylboronic Acids
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The synthesis of diarylamine is extremely important in organic chemistry. Herein, a novel electrochemical reductive arylation of nitroarenes with arylboronic acids was developed. A variety of diarylamines were synthesized without the need for transition-metal catalysts. The reaction could be scaled up efficiently in a flow cell and several derivatization reactions were carried out smoothly. Cyclic voltammetry experiments and mechanism studies showed that acetonitrile, formic acid, and triethyl phosphite all played a role in promoting this reductive arylation transformation.
- Wang, Dan,Wan, Zhaohua,Zhang, Heng,Alhumade, Hesham,Yi, Hong,Lei, Aiwen
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p. 5399 - 5404
(2021/10/20)
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- Visible-Light- And PPh3-Mediated Direct C-N Coupling of Nitroarenes and Boronic Acids at Ambient Temperature
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We present here a metal-free, visible-light- and triphenylphosphine-mediated intermolecular, reductive amination between nitroarenes and boronic acids at ambient temperature without any photocatalyst. Mechanistically, a slow reduction of nitroarenes to a nitroso and, finally, a nitrene intermediate occurs that leads to the amination product with concomitant 1,2-aryl/-alkyl migration from a boronate complex. A wide range of nitroarenes underwent C-N coupling with aryl-/alkylboronic acids providing high yields.
- Manna, Kartic,Ganguly, Tanusree,Baitalik, Sujoy,Jana, Ranjan
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supporting information
p. 8634 - 8639
(2021/11/01)
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- Chan-Evans-Lam C?N Coupling Promoted by a Dinuclear Positively Charged Cu(II) Complex. Catalytic Performance and Some Evidence for the Mechanism of CEL Reaction Obviating Cu(III)/Cu(I) Catalytic Cycle
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In the present study, we report the synthesis of a series of copper(II) complexes with a wide range of ligands and their testing in the copper catalyzed Chan-Evans-Lam (CEL) coupling of aniline and phenylboronic acid. The efficiency of the coupling was directly connected with the ease of the reduction of Cu(II) to Cu(I) of the complexes. The most efficient catalyst was derived from 4-t-butyl-2,5-bis[(quinolinylimino)methyl]phenolate and two Cu(II) ions. Depending on the counter-anion nature and the concentration of the reaction mixture, the reaction can be directed to predominant C?N-bond formation. Forty-three derivatives of diphenylamine were prepared under the optimized conditions. The proposed mechanism of the catalysis was based on the reduction potential of a series of complexes, molecular weight measurements of the catalytic complex in MeOH and the kinetic studies of aniline and phenylboronic acid coupling. In addition, an 1H NMR experiment in a sealed NMR tube, without external oxygen supply available, proved that no complete Cu(II) to Cu(I) conversion was observed under the condition, ruling out the usually accepted mechanism of the C?N coupling, which included the oxygenation of the intermediately formed Cu(I) complexes after the key step of C?N conversion had already been completed. Instead, a mechanism was proposed, involving an oxygen molecule coordinated to two copper ions in the key C?N bond formation without any detectable conversion of the Cu(II) complexes to Cu(I).
- Akatyev, Nikolay,Il'in, Mikhail,Il'in, Mikhail,Peregudova, Svetlana,Peregudov, Alexander,Buyanovskaya, Anastasiya,Kudryavtsev, Kirill,Dubovik, Alexander,Grinberg, Valerij,Orlov, Victor,Pavlov, Alexander,Novikov, Valentin,Volkov, Ilya,Belokon, Yuri
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p. 3010 - 3021
(2020/04/29)
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- Continuous Synthesis of Aryl Amines from Phenols Utilizing Integrated Packed-Bed Flow Systems
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Aryl amines are important pharmaceutical intermediates among other numerous applications. Herein, an environmentally benign route and novel approach to aryl amine synthesis using dehydrative amination of phenols with amines and styrene under continuous-flow conditions was developed. Inexpensive and readily available phenols were efficiently converted into the corresponding aryl amines, with small amounts of easily removable co-products (i.e., H2O and alkanes), in multistep continuous-flow reactors in the presence of heterogeneous Pd catalysts. The high product selectivity and functional-group tolerance of this method allowed aryl amines with diverse functional groups to be selectively obtained in high yields over a continuous operation time of one week.
- Ichitsuka, Tomohiro,Kobayashi, Shū,Koumura, Nagatoshi,Sato, Kazuhiko,Takahashi, Ikko
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supporting information
p. 15891 - 15896
(2020/07/13)
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- Synthesis of unsymmetrically substituted triarylaminesviaacceptorless dehydrogenative aromatization using a Pd/C andp-toluenesulfonic acid hybrid relay catalyst
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An efficient and convenient procedure for synthesizing triarylamines based on a dehydrogenative aromatization strategy has been developed. A hybrid relay catalyst comprising carbon-supported Pd (Pd/C) andp-toluenesulfonic acid (TsOH) was found to be effective for synthesizing a variety of triarylamines bearing different aryl groups starting from arylamines (diarylamines or anilines), using cyclohexanones as the arylation sources under acceptorless conditions with the release of gaseous H2. The proposed reaction comprises the following relay steps: condensation of arylamines and cyclohexanones to produce imines or enamines, dehydrogenative aromatization of the imines or enamines over Pd nanoparticles (NPs), and elimination of H2from the Pd NPs. In this study, an interesting finding was obtained indicating that TsOH may promote the dehydrogenation.
- Jin, Xiongjie,Koizumi, Yu,Mizuno, Noritaka,Nozaki, Kyoko,Takayama, Satoshi,Yamaguchi, Kazuya,Yatabe, Takafumi
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p. 4074 - 4084
(2020/05/25)
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- Imidazole-directed fabrication of three polyoxovanadate-based copper frameworks as efficient catalysts for constructing C-N bonds
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A synthetic pathway for the directed preparation of three novel polyoxovanadate-based copper frameworks (POVCFs), i.e., [Cu0.5(1-ipIM)2]2[V4O11] (POVCF 1), [Cu(1-ipIM)2](VO3)2 (POVCF 2) and [Cu(1-pIM)4](HpIM)4[V10O28] (POVCF 3) (1-ipIM = 1-isopropylimidazole; 1-pIM = 1-propylimidazole) using bifunctional imidazole molecules as organic ligands and base has been developed. Systematic studies revealed that the variable base enviroment in the reaction is the key step in the preparation of 1D to 3D supermolecular networks of POVCFs 1-3. Single crystal X-ray diffraction analyses demonstrated that the Cu2+ atoms of POVCFs 1-2 were coordinated with four imidazole derivative molecules and two different polyoxovanadate {[V4O11]2- and [V10O28]6-} clusters, respectively, exhibiting a [CuN4O2] binding set and a distorted octahedral geometry. Specifically, POVCF 1 exhibited adjacent [V4O11]2- that dangle up and down arranged in a parallel 2D network and further coordinated with [Cu(1-ipIM)4]2+ to form a 3D supramolecular structure. However, POVCF 3 presented one tetrahedral coordinated vanadium atom and one four-coordinated copper atom and they further gave rise to a 1D network by the Cu-O and V-O bonds. More importantly, these POVCFs were further studied in the construction of C-N bond reactions of primary amines under mild conditions, and it was found that POVCF 1 displayed efficient heterogeneous catalytic activities in the Chan-Lam reaction (yields up to 89%). This journal is
- Gong, Shuwen,Gu, Yuxiao,Huang, Xianqiang,Li, Jikun,Li, Qiang,Qi, Yuquan,Shen, Guodong
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p. 10970 - 10976
(2020/09/02)
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- Cp*Co(iii) and Cu(OAc)2bimetallic catalysis for Buchwald-type C-N cross coupling of aryl chlorides and amines under base, inert gas & solvent-free conditions
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A strategy involving bimetallic catalysis with a combination of Cp?Co(CO)I2 and Cu(OAc)2 was used for performing Buchwald-type C-N coupling reactions of aryl chlorides with amines. The reactions proceeded at 100 °C to produce excellent yields of many of the desired C-N coupled products, in 4 h, under aerobic reaction conditions. The reactions were shown to run under base-free and solvent-free conditions, enabling this strategy to work efficiently for electron-withdrawing and base-sensitive functionalities. The presented methodology was found to be equally efficient for electron-donating functionalities as well as for primary (1°) and secondary (2°) aromatic and aliphatic amines. Moreover, the products were easily separated through the extractions of the organic aqueous layer, with this process chromatographic separations is not required.
- Srivastava, Avinash K.,Sharma, Charu,Joshi, Raj K.
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supporting information
p. 8248 - 8253
(2020/12/29)
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- C–N Cross-coupling Reactions of Amines with Aryl Halides Using Amide-Based Pincer Nickel(II) Catalyst
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Abstract: An approach to C–N cross-coupling reactions of aryl halides with amines in the presence of an amide-based pincer nickel(II) catalyst (2) is described. For 3?h reactions at 110?°C with 0.2?mol% catalyst, aryl bromides gave higher turnover numbers (TON) than the corresponding chlorides or iodides. Both primary and secondary amines could be used with the former giving higher TON. However, sterically hindered amines showed lower TON. In elucidating the mechanism of this nickel complex-catalyzed C–N cross coupling reaction it was found that the rate of reaction was unchanged in the presence of radical quenchers and a plausible Ni(I)–Ni(III) pathway is proposed. Graphic Abstract: [Figure not available: see fulltext.]Nickel pincer catalyst proved to be excellent catalyst for the C-N cross-coupling reaction with the high turnover number (TON) for 1° and 2° amines and different nonactivated aryl halides under optimum conditions.
- Albkuri, Yahya M.,RanguMagar, Ambar B.,Brandt, Andrew,Wayland, Hunter A.,Chhetri, Bijay P.,Parnell, Charlette M.,Szwedo, Peter,Parameswaran-Thankam, Anil,Ghosh, Anindya
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p. 1669 - 1678
(2019/12/27)
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- Half-sandwich (η5-Cp?)Rh(iii) complexes of pyrazolated organo-sulfur/selenium/tellurium ligands: Efficient catalysts for base/solvent free C-N coupling of chloroarenes under aerobic conditions
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Three new pyrazolated chalcogenoether ligated Rh(iii) half-sandwich complexes (1-3) were synthesised by the thermal reaction of chalcogenoether (S, Se and Te) substituted 1H-pyrazole ligands (L1-L3) and [(η5-C5Me5)RhCl]2 in methanol. The complexes were fully characterised by various spectroscopic techniques, and the molecular structures of complexes 1 and2 were also established through single crystal X-ray crystallographic analysis, which indicates a pseudo-octahedral half-sandwich piano-stool geometry around the rhodium metal. All three complexes were found to be thermally stable and insensitive towards air and moisture. One mol% of Rh(iii) complexes (1-3) along with 10 mol% of Cu(OAc)2 were explored for the Buchwald-Hartwig type C-N coupling reactions of amine and aryl chloride. Good to excellent yields (89-92%) of the coupling products were obtained with seleno- and thio-ether functionalised pyrazolated Rh(iii) complexes (1 and 2), while an average yield (39%) was obtained with the telluro-ether functionalised complex (3). In contrast to the previously reported C-N coupling reactions the present reaction works under solvent- and base-free conditions, and the coupling reaction is accomplished in just 6 h with a high yield of the coupling product. The present methodology was also found to be efficient for a wide variety of functionalised aryl halides, and aliphatic or aromatic amines (1° and 2°). Moreover, the reaction also enables the C-N coupling of electron-withdrawing substrates and base-sensitive functionalities.
- Joshi, Raj Kumar,Sharma, Charu,Sharma, Kamal Nayan,Srivastava, Avinash Kumar
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supporting information
p. 3599 - 3606
(2020/06/10)
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- One-pot synthesis of symmetrical and asymmetrical diphenylamines from guanidines with aryl iodide using Cu/Cu2O nanocatalyst
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This work reports the selective one-pot synthesis of symmetrical and asymmetrical amines from guanidines as ammonia surrogate. The use of guanidine as ammonia source will eliminate the need of handling liquid ammonia. The reaction was performed using Cu/Cu2O nanocatalyst under ligand-free condition. The synthesized catalyst was characterized by a various technique like XRD, FEG-SEM, HRTEM and XPS. The different diphenylamines are produced in good to very good yields. Recyclability study of catalyst shows that up to five cycles there is no significant loss in its activity.
- Chaurasia, Shivkumar R.,Bhanage
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- Nickel-Catalyzed Amination of Aryl Thioethers: A Combined Synthetic and Mechanistic Study
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Herein, we report a nickel-1,2-bis(dicyclohexylphosphino)ethane (dcype) complex for the catalytic Buchwald-Hartwig amination of aryl thioethers. The protocol shows broad applicability with a variety of different functional groups tolerated under the catalytic conditions. Extensive organometallic and kinetic studies support a nickel(0)-nickel(II) pathway for this transformation and revealed the oxidative addition complex as the resting state of the catalytic cycle. All the isolated intermediates have proven to be catalytically and kinetically competent catalysts for this transformation. The fleeting transmetalation intermediate has been successfully synthesized through an alternative synthetic organometallic pathway at lower temperature, allowing for in situ NMR study of the C-N bond reductive elimination step. This study addresses key factors governing the mechanism of the nickel-catalyzed Buchwald-Hartwig amination process, thus improving the understanding of this important class of reactions.
- Bismuto, Alessandro,Delcaillau, Tristan,Müller, Patrick,Morandi, Bill
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p. 4630 - 4639
(2020/05/19)
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- An Improved PIII/PV=O-Catalyzed Reductive C-N Coupling of Nitroaromatics and Boronic Acids by Mechanistic Differentiation of Rate- And Product-Determining Steps
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Experimental, spectroscopic, and computational studies are reported that provide an evidence-based mechanistic description of an intermolecular reductive C-N coupling of nitroarenes and arylboronic acids catalyzed by a redox-active main-group catalyst (1,2,2,3,4,4-hexamethylphosphetane P-oxide, i.e., 1·[O]). The central observations include the following: (1) catalytic reduction of 1·[O] to PIII phosphetane 1 is kinetically fast under conditions of catalysis; (2) phosphetane 1 represents the catalytic resting state as observed by 31P NMR spectroscopy; (3) there are no long-lived nitroarene partial-reduction intermediates observable by 15N NMR spectroscopy; (4) the reaction is sensitive to solvent dielectric, performing best in moderately polar solvents (viz. cyclopentylmethyl ether); and (5) the reaction is largely insensitive with respect to common hydrosilane reductants. On the basis of the foregoing studies, new modified catalytic conditions are described that expand the reaction scope and provide for mild temperatures (T ≥ 60 °C), low catalyst loadings (≥2 mol%), and innocuous terminal reductants (polymethylhydrosiloxane). DFT calculations define a two-stage deoxygenation sequence for the reductive C-N coupling. The initial deoxygenation involves a rate-determining step that consists of a (3+1) cheletropic addition between the nitroarene substrate and phosphetane 1; energy decomposition techniques highlight the biphilic character of the phosphetane in this step. Although kinetically invisible, the second deoxygenation stage is implicated as the critical C-N product-forming event, in which a postulated oxazaphosphirane intermediate is diverted from arylnitrene dissociation toward heterolytic ring opening with the arylboronic acid; the resulting dipolar intermediate evolves by antiperiplanar 1,2-migration of the organoboron residue to nitrogen, resulting in displacement of 1·[O] and formation of the target C-N coupling product upon in situ hydrolysis. The method thus described constitutes a mechanistically well-defined and operationally robust main-group complement to the current workhorse transition-metal-based methods for catalytic intermolecular C-N coupling.
- Li, Gen,Nykaza, Trevor V.,Cooper, Julian C.,Ramirez, Antonio,Luzung, Michael R.,Radosevich, Alexander T.
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supporting information
p. 6786 - 6799
(2020/04/30)
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- Diaza crown-type macromocycle (kryptofix 22) functionalised carbon nanotube for efficient Ni2+ loading; A unique catalyst for cross-coupling reactions
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Raising the capability of supporting and suppressing the leaching possibility to a very insignificant level has still remained challenging for some class of transition metals, i.e. Ni2+. Here we present the covalent functionalisation of macrocyclic ligand, 4,13-diaza-18-crown-6 (kryptofix 22), on the surface of carbon nanotube (CNT), leading to a unique adsorptive capability for supporting Ni2+. This material was incorporated as a promising catalyst in coupling reactions including C[sbnd]C, CN, and CO[sbnd][sbnd] cross-coupling reactions. We demonstrate that the kryptofix 22 functionalisation on the surface of CNT has a key role in the enhancement of the adsorption capability Ni2+ and subsequent catalytic activity. We further prove that this ligand causes a significant boost in the recyclability of the reactions due to the extremely trivial Ni2+ leaching from the CNT's surface during the reactions.
- Aalinejad, Michael,Doustkhah, Esmail,Pesyan, Nader Noroozi
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- CoII immobilized on an aminated magnetic metal-organic framework catalyzed C-N and C-S bond forming reactions: A journey for the mild and efficient synthesis of arylamines and arylsulfides
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In this work, we report a simple and versatile method for the modification of a metal-organic framework (NH2-MIL53(Al)) in a step-wise manner. To characterize the synthesized nanostructured catalyst, a variety of spectroscopic and microscopic techniques including FT-IR, XRD, BET, TEM, FE-SEM, EDX, EDX-mapping, TGA, XPS, VSM, ICP-OES and CHN have been employed. Fe3O4@AMCA-MIL53(Al)-NH2-CoII NPs, which benefit from small nanocrystalline size (10-30 nm, according to the XRD and TEM data) in combination with the coexistence of magnetic nanoparticles, a metal-organic framework, and cobalt species, were found to be an excellent environment catalyst to promote the C-N and C-S cross coupling reactions. A wide range of functional substrates including electron-withdrawing and electron-donating aryl halides underwent the coupling reaction with aromatic/heteroaromatic/benzylic and aliphatic amines and sulfides. The results demonstrated that the yields of the target products were good to excellent and the catalyst can be recycled for at least seven recycling runs without a discernible decrease in its catalytic activity. Furthermore, the heterogeneity studies (such as hot filtration and poisoning tests) efficiently confirmed that the as-synthesized nanostructured catalyst is heterogeneous and completely stable under the reaction conditions. We hope that our study inspires more interest in designing novel catalysts based on using low-cost metal ions (such as cobalt) in the field of cross coupling reactions.
- Mohammadinezhad, Arezou,Akhlaghinia, Batool
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supporting information
p. 15525 - 15538
(2019/10/19)
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- Nickel-catalyzed N-arylation of amines with arylboronic acids under open air
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In this study, a well-defined, novel NHC-Ni complex was developed and used to catalyze the N-arylation of alkyl- and arylamines with arylboronic acids in a rare version of Chan-Lam coupling. Although the same coupling using copper catalysts has been widely studied, the nickel-catalyzed version is rare and normally requires 10–20 mol% catalyst loading. This novel NHC-Ni complex in combination with 4,4′-dimethyl-2,2′-bipyridine, however, proved to be an effective catalyst that lowered the required catalyst loading to only 2.0 mol%.
- Ando, Shin,Hirota, Yurina,Matsunaga, Hirofumi,Ishizuka, Tadao
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supporting information
p. 1277 - 1280
(2019/04/10)
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- Recyclable bimetallic CuMoO4 nanoparticles for C-N cross-coupling reaction under mild conditions
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Herein we disclosed inexpensive copper(ii) bimetallic CuMoO4 nanoparticles for the C-N cross-coupling reaction of alkyl and aryl amines with haloarenes. The reaction proceeds under mild and ligand free conditions. The catalyst is recyclable and effective for a wide range of amines and haloarenes. Here, the efficiency of the Cu(ii) catalyst is increased by doping molybdenum metal. The bimetallic nanoparticles are anticipated to proceed via normal oxidative addition and reductive eliminations.
- Panigrahi, Reba,Panda, Subhalaxmi,Behera, Pradyota Kumar,Sahu, Santosh Kumar,Rout, Laxmidhar
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supporting information
p. 19274 - 19278
(2019/12/24)
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- Organic electroluminescent material and organic electroluminescent device containing same
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The invention provides an organic electroluminescent material and an organic electroluminescent device containing the same, and belongs to the technical field of electroluminescence. According to thematerial, adamantane is introduced to serve as a new core group based on a bis(triarylamine) symmetric structure, the molecular shape is changed, the structure symmetricity is reduced, and the film forming property of a material is promoted; the adamantane has relatively large steric hindrance and rigid structure, and the non-conjugated molecular structure of adamantane cannot influence the electronic energy level of triarylamine, so that the hole transmission performance of the material is ensured; and the compound containing the adamantane group has excellent hole transmission performance, and can be used for manufacturing an organic electroluminescent device, especially a hole transmission layer material in the organic electroluminescent device, so as to effectively improve the luminescence efficiency and prolong the service life of the organic electroluminescent device.
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Paragraph 0101; 0102
(2019/04/27)
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- Palladium-Catalyzed Amidation and Amination of (Hetero)aryl Chlorides under Homogeneous Conditions Enabled by a Soluble DBU/NaTFA Dual-Base System
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The palladium-catalyzed coupling of aryl and heteroaryl chlorides with primary amides under mild homogeneous reaction conditions is reported. Successful C-N coupling is enabled by the use of a unique "dual-base" system consisting of DBU and NaTFA, which serve as proton acceptor and halide scavenger, respectively, using low catalyst loadings (0.5 mol %) with readily available, air-stable palladium precatalysts. The DBU/NaTFA system also enables the room-temperature coupling of primary aryl amines with aryl chlorides and is tolerant of a variety of base-sensitive functional groups.
- Beutner, Gregory L.,Coombs, John R.,Green, Rebecca A.,Inankur, Bahar,Lin, Dong,Qiu, Jun,Roberts, Frederick,Simmons, Eric M.,Wisniewski, Steven R.
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supporting information
p. 1529 - 1537
(2019/09/04)
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- Transition-Metal-Free Synthesis of 1,2-Disubstituted Indoles
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Herein, we report a new transition-metal-free robust and cost-effective method for synthesis of 1,2-disubstituted indoles from easily available unactivated (i.e. without EWG, PPh3 or SiR3 groups) tertiary amides. Scope of synthetic applicability of the presented protocol was shown on 23 examples of 1,2-disubstituted indoles with different substitution patterns obtained in good to excellent yields. The reported method turned out to be especially effective for synthesis of N-arylated 2-CF3-indoles. Moreover, this approach can be performed in a one-pot two-step manner directly from commercially available secondary amines. Mechanistic studies showed that acyl transfer might be an important step in the course of the reaction. Viability of the presented approach for benzofurans and benzothiophenes synthesis was also discussed.
- Chesnokov, Gleb A.,Ageshina, Alexandra A.,Topchiy, Maxim A.,Nechaev, Mikhail S.,Asachenko, Andrey F.
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supporting information
p. 4844 - 4854
(2019/08/01)
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- Copper(ii)-catalyzed c-n coupling of aryl halides and n-nucleophiles promoted by quebrachitol or diethylene glycol
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Herein, we report the natural ligand quebrachitol (QCT) as a promoter for a Cu(II) catalyst, which is highly effective for N-Arylation of various amines and related aryl halides. A series of diarylamine derivatives were obtained in high yields by using diethylene glycol (DEG) as both ligand and solvent. The C-N coupling reactions proceed under mild conditions and exhibit good functional group tolerance.
- Chen, Guoliang,Chen, Yuanguang,Du, Fangyu,Fu, Yang,Wu, Ying,Zhou, Qifan
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supporting information
p. 2161 - 2168
(2019/11/25)
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- Ullmann-type: N-arylation of anilines with alkyl(aryl)sulfonium salts
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A palladium/copper-cocatalyzed Ullmann-type N-arylation of anilines using alkyl(aryl)sulfonium triflates as arylation reagents has been accomplished. The reaction enabled Caryl-S bond cleavage over Calkyl-S bond breakage of alkyl(aryl)sulfoniums by Pd(P(tBu)3)2/CuI and gave the corresponding N-arylated products in good to high yields. It was also significant that the reactions of aniline with asymmetric butyl(mesityl)(aryl)sulfonium triflates showed excellent selectivity, in which the aryl groups other than the bulky and electron-rich mesityl moieties were transformed.
- Tian, Ze-Yu,Zhang, Cheng-Pan
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p. 11936 - 11939
(2019/10/11)
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- Palladium-catalyzed c(sp2)-n bond cross-coupling with triaryl phosphates
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The first general palladium-catalyzed amination of aryl phosphates is described. The combination of MorDalPhos with [Pd(-cinnamyl)Cl]2 enables the amination of electron-rich, electron-neutral, and electron-poor aryl phosphates with a board range of aromatic, aliphatic, and heterocyclic amines. Common functional groups such as ether, keto, ester, and nitrile show an excellent compatibility in this reaction condition. The solvent-free amination reactions are also successful in both solid coupling partners. The gram-scale cross-coupling is achieved by this catalytic system.
- Chen, Zicong,Chen, Xiangmeng,So, Chau Ming
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- Palladium-Catalyzed C(sp2)-N Bond Cross-Coupling with Triaryl Phosphates
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The first general palladium-catalyzed amination of aryl phosphates is described. The combination of MorDalPhos with [Pd(?-cinnamyl)Cl]2 enables the amination of electron-rich, electron-neutral, and electron-poor aryl phosphates with a board range of aromatic, aliphatic, and heterocyclic amines. Common functional groups such as ether, keto, ester, and nitrile show an excellent compatibility in this reaction condition. The solvent-free amination reactions are also successful in both solid coupling partners. The gram-scale cross-coupling is achieved by this catalytic system.
- Chen, Zicong,Chen, Xiangmeng,So, Chau Ming
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p. 6366 - 6376
(2019/05/24)
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- Reductive Molybdenum-Catalyzed Direct Amination of Boronic Acids with Nitro Compounds
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The synthesis of aromatic amines is of utmost importance in a wide range of chemical contexts. We report a direct amination of boronic acids with nitro compounds to yield (hetero)aryl amines. The novel combination of a dioxomolybdenum(VI) catalyst and triphenylphosphine as inexpensive reductant has revealed to be decisive to achieve this new C?N coupling. Our methodology has proven to be scalable, air and moisture tolerant, highly chemoselective and engages both aliphatic and aromatic nitro compounds. Moreover, this general and step-economical synthesis of aromatic secondary amines showcases orthogonality to other aromatic amine syntheses as it tolerates aryl halides and carbonyl compounds.
- Suárez-Pantiga, Samuel,Hernández-Ruiz, Raquel,Virumbrales, Cintia,Pedrosa, María R.,Sanz, Roberto
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supporting information
p. 2129 - 2133
(2019/01/25)
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- Synthesis method for converting lignin 4-O-5 model compound diaryl ether into nitrogen-containing compound
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The invention discloses a synthesis method for converting lignin 4-O-5 model compound diaryl ether into a nitrogen-containing compound. According to the synthesis method, a diaryl ether compound andan amine compound are subjected to a heating reaction in a certain amount of a solvent (containing a certain amount of water) in an argon atmosphere (containing a certain amount of air) under the actions of a metal catalyst and sodium borohydride, such that the drug with the important physiological activity or the compound with the natural product skeleton containing nitrogen is formed by directlycoupling the C-O bond cut and the amine compound cross while the corresponding aromatic hydrocarbon is obtained. According to the present invention, the synthesis method has characteristics of simpleand easily-available raw materials, high conversion rate, important product and good yield, and has broad application prospects in the degradation and deep development and utilization of lignin.
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Paragraph 0039-0041
(2019/04/26)
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- NIXANTPHOS: A highly active ligand for palladium catalyzed Buchwald-Hartwig amination of unactivated aryl chlorides
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Xantphos is one of the two most common ligands used in palladium catalyzed Buchwald-Hartwig amination reactions, because of its broad scope and high probability of success. It does not, however, work well with unactivated aryl chlorides. Herein NIXANTPHOS is compared to Xantphos and an array of mono- and bidentate phosphines. NIXANTPHOS outperforms Xantphos and all other bidentate ligands examined. Under the optimal reaction conditions, unactivated aryl chlorides afford the expected products in good to excellent yield with as low as 0.05 mol% (500 ppm) palladium loading.
- Mao, Jianyou,Zhang, Jiadi,Zhang, Shuguang,Walsh, Patrick J.
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supporting information
p. 8690 - 8696
(2018/07/13)
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- Method for preparing secondary aromatic amine or tertiary aromatic amine by conducting amination on aryl halide or alkyl halide
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The invention discloses a method for preparing secondary aromatic amine or tertiary aromatic amine by conducting amination on aryl halide or alkyl halide. That is to say, the alkyl halide or the arylhalide and organic amine are mixed according to a certain ratio, and under light irradiation, C-N coupling reaction is carried out, so that a corresponding target product is generated for preparing the secondary amine or the tertiary amine. Compared with existing synthesis technologies, the method has the advantages that the aryl halide or the alkyl halide which is cheap and easy to get is selected as a reaction substrate, the method has good universality for different organic amine separately, moreover, the product selectivity is high, and separation and purification are easy; moreover, the synthesis method does not need to be conducted under severe conditions of high temperature and the like, a green and sustainable light source is adopted as driving force, the atom economy is high, andthe method has wide application prospects.
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Paragraph 0029-0035; 0160; 0064; 0065; 0074; 0075; 0161
(2019/01/14)
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- Palladium-Catalyzed Formal Cross-Coupling of Diaryl Ethers with Amines: Slicing the 4-O-5 Linkage in Lignin Models
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Lignin is the second most abundant organic matter on Earth, and is an underutilized renewable source for valuable aromatic chemicals. For future sustainable production of aromatic compounds, it is highly desirable to convert lignin into value-added platform chemicals instead of using fossil-based resources. Lignins are aromatic polymers linked by three types of ether bonds (α-O-4, β-O-4, and 4-O-5 linkages) and other C?C bonds. Among the ether bonds, the bond dissociation energy of the 4-O-5 linkage is the highest and the most challenging to cleave. To date, 4-O-5 ether linkage model compounds have been cleaved to obtain phenol, cyclohexane, cyclohexanone, and cyclohexanol. The first example of direct formal cross-coupling of diaryl ether 4-O-5 linkage models with amines is reported, in which dual C(Ar)?O bond cleavages form valuable nitrogen-containing derivatives.
- Zeng, Huiying,Cao, Dawei,Qiu, Zihang,Li, Chao-Jun
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supporting information
p. 3752 - 3757
(2018/03/13)
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- Chitosan-Supported Ni particles: An Efficient Nanocatalyst for Direct Amination of Phenols
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A practical method for the direct amination of phenols using 2,4,6-trichloro-1,3,5-triazine (TCT) as an efficient promotor for the activation of phenols in the presence of an efficient and recyclable heterogeneous catalyst prepared by immobilization of nickel particles on triazole modified chitosan is described. This heterogeneous catalyst has demonstrated a promising activity for the conversion of phenolic compounds to their corresponding amine under mild conditions. Moreover, the obtained catalyst can be reused in five consecutive runs with consistent catalytic activity.
- Hajipour, Abdol R.,Abolfathi, Parisa
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- Synthesis of Arylamines via Non-Aerobic Dehydrogenation Using a Palladium/Carbon-Ethylene System
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The reaction of cyclohexanones with amines proceeded under an ethylene atmosphere in the presence of a catalytic amount of palladium/carbon to afford a variety of arylamines in good to high yields. The present reaction was carried out under completely non-aerobic conditions, and which is in contrast with the previously reported aerobic system. has wide applicability affording a variety of aromatic amines, and co-product of the reaction is only gaseous ethane. Thus, this method is environmentally friendly. This protocol was applied intramolecularly to provide a novel method for the construction of quinoline and isoquinoline compounds. (Figure presented.).
- Shimomoto, Yuya,Matsubara, Ryosuke,Hayashi, Masahiko
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supporting information
p. 3297 - 3305
(2018/08/07)
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- Synthesis and characterization of MCM-41-Biurea-Pd as a heterogeneous nanocatalyst and using its catalytic efficacy in C–C, C–N and C–O coupling reactions
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MCM-41-Biurea-Pd is introduced as a new, heterogeneous and reusable catalyst for C–C and C–heteroatom bond formation between various aryl halides, phenols and amines, in the presence of Ph3SnCl (Stille reaction) in PEG-400 as a green solvent at room temperature. The structure of the functionalized MCM-41 was analysed using various techniques.
- Batmani, Hana,Noroozi Pesyan, Nader,Havasi, Forugh
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- N/O-doped carbon as a "solid ligand" for nano-Pd catalyzed biphenyl- and triphenylamine syntheses
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A series of N/O-doped porous carbon supported nanopalladium catalysts have been successfully prepared, in which the N/O doped carbons were controllably produced via polypyrrole/furan synthesis followed by carbonization. These catalysts exhibit good performance in biphenylamine and triphenylamine syntheses with nitrobenzene and cyclohexanone as starting materials. Their catalytic activity can be tuned efficiently by the N/O functional groups on the carbon surface. TEM, XRD, XPS and laser Raman methods were applied to probe the structure of these catalysts. These results indicate that the Pd nanoparticles were supported on N/O-doped porous carbon via the "coordination" between Pd nanoparticles and N/O functional groups including O-CO, CN and tertiary nitrogen, and better catalytic performance was obtained if carbon with the highest N-species loading was used as the support. In addition, a mechanistic study proved that the reaction starts with the catalytic reduction of nitrobenzene with cyclohexanone as the hydrogen source. During this reaction, aniline was formed and the cyclohexanone was transformed into phenol. Then biphenylamine and triphenylamine were generated through the reaction of aniline and cyclohexanone. This work should facilitate the controllable preparation of carbon supported nanocatalysts with specific activity, and open up a promising pathway for the development of new methodologies for N-containing fine chemical synthesis.
- Pang, Shaofeng,Zhang, Yujing,Huang, Yongji,Yuan, Hangkong,Shi, Feng
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p. 2170 - 2182
(2017/07/24)
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- Versatile routes for synthesis of diarylamines through acceptorless dehydrogenative aromatization catalysis over supported gold-palladium bimetallic nanoparticles
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Diarylamines are an important class of widely utilized chemicals, and development of diverse procedures for their synthesis is of great importance. Herein, we have successfully developed novel versatile catalytic procedures for the synthesis of diarylamines through acceptorless dehydrogenative aromatization. In the presence of a gold-palladium alloy nanoparticle catalyst (Au-Pd/TiO2), various symmetrically substituted diarylamines could be synthesized starting from cyclohexylamines. The observed catalysis of Au-Pd/TiO2 was heterogeneous in nature and Au-Pd/TiO2 could be reused several times without severe loss of catalytic performance. This transformation needs no oxidants and generates molecular hydrogen (three equivalents with respect to cyclohexylamines) and ammonia as the side products. These features highlight the environmentally benign nature of the present transformation. Furthermore, in the presence of Au-Pd/TiO2, various kinds of structurally diverse unsymmetrically substituted diarylamines could successfully be synthesized starting from various combinations of substrates such as (i) anilines and cyclohexanones, (ii) cyclohexylamines and cyclohexanones, and (iii) nitrobenzenes and cyclohexanols. The role of the catalyst and the reaction pathways were investigated in detail for the transformation of cyclohexylamines. The catalytic performance was strongly influenced by the nature of the catalyst. In the presence of a supported gold nanoparticle catalyst (Au/TiO2), the desired diarylamines were hardly produced. Although a supported palladium nanoparticle catalyst (Pd/TiO2) gave the desired diarylamines, the catalytic activity was inferior to that of Au-Pd/TiO2. Moreover, the activity of Au-Pd/TiO2 was superior to that of a physical mixture of Au/TiO2 and Pd/TiO2. The present Au-Pd/TiO2-catalyzed transformation of cyclohexylamines proceeds through complex pathways comprising amine dehydrogenation, imine disproportionation, and condensation reactions. The amine dehydrogenation and imine disproportionation reactions are effectively promoted by palladium (not by gold), and the intrinsic catalytic performance of palladium is significantly improved by alloying with gold. One possible explanation of the alloying effect is the formation of electron-poor palladium species that can effectively promote the β-H elimination step in the rate-limiting amine dehydrogenation.
- Taniguchi, Kento,Jin, Xiongjie,Yamaguchi, Kazuya,Nozaki, Kyoko,Mizuno, Noritaka
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p. 2131 - 2142
(2017/03/09)
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- N-heterocyclic carbene-palladium complex, and preparation method and application thereof
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The invention discloses an N-heterocyclic carbene-palladium complex, and a preparation method and application thereof. The N-heterocyclic carbene-palladium complex disclosed by the invention is shown in Formula (I), wherein L1 is a quinoline ligand or isoquinoline ligand, and N in the L1 is connected with Pd; L2 is an N-heterocyclic carbene ligand, and carbene carbon in the L2 is connected with the Pd; and X1 and X2 are respectively independently an anionic ligand. The N-heterocyclic carbene-palladium complex disclosed by the invention can efficiently catalyze carbon-carbon or carbon-heteroatom coupling reaction using aryl halide as a substrate. The formula is shown in the specification.
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Paragraph 0140; 0141; 0142
(2017/07/22)
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- Synthesis of N-heterocyclic carbene-Pd(II) complexes and their catalytic activity in the Buchwald-Hartwig amination of aryl chlorides
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Novel N-heterocyclic carbene-palladium(II) complexes using 2-picolinic acid as the ancillary ligand have been successfully developed under mild conditions. Their catalytic activity in organic synthesis has been initially tested in the Buchwald-Hartwig amination of secondary and primary amines with aryl chlorides. Various substituents on both substrates can be tolerated, giving the desired coupling products in good to almost quantitative yields. The minimum catalyst loading can be 0.01 mol%, implying their potential application toward industrial processes.
- Zhang, Zhi-Mao,Gao, Yu-Jue,Lu, Jian-Mei
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p. 7308 - 7314
(2017/12/01)
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- Mechanistic Insight Leads to a Ligand Which Facilitates the Palladium-Catalyzed Formation of 2-(Hetero)Arylaminooxazoles and 4-(Hetero)Arylaminothiazoles
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By using mechanistic insight, a new ligand (EPhos) for the palladium-catalyzed C?N cross-coupling between primary amines and aryl halides has been developed. Employing an isopropoxy group at the C3-position favors the C-bound isomer of the ligand-supported palladium(II) complexes and leads to significantly improved reactivity. The use of a catalyst system based on EPhos with NaOPh as a mild homogeneous base proved to be very effective in the formation of 4-arylaminothiazoles and highly functionalized 2-arylaminooxazoles. Previously, these were not readily accessible using palladium catalysis.
- Olsen, Esben P. K.,Arrechea, Pedro L.,Buchwald, Stephen L.
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supporting information
p. 10569 - 10572
(2017/08/22)
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- Molecular Adsorbates Switch on Heterogeneous Catalysis: Induction of Reactivity by N-Heterocyclic Carbenes
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We report the N-heterocyclic carbene (NHC)-induced activation of an otherwise unreactive Pd/Al2O3 catalyst. Surface analysis techniques demonstrate the NHC being coordinated to the palladium particles and affecting their electronic properties. Ab initio calculations provide further insight into the electronic effect of the coordination with the NHC injecting electron density into the metal nanocluster thus lowering the barrier for bromobenzene activation. By this NHC modification, the catalyst could be successfully applied in the Buchwald-Hartwig amination of aryl chlorides, bromides, and iodides. Various heterogeneity tests could additionally show that the reaction proceeds via a heterogeneous active species.
- Ernst, Johannes B.,Schwermann, Christian,Yokota, Gen-Ichi,Tada, Mizuki,Muratsugu, Satoshi,Doltsinis, Nikos L.,Glorius, Frank
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supporting information
p. 9144 - 9147
(2017/07/22)
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- Spectroscopic Studies of the Chan-Lam Amination: A Mechanism-Inspired Solution to Boronic Ester Reactivity
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We report an investigation of the Chan-Lam amination reaction. A combination of spectroscopy, computational modeling, and crystallography has identified the structures of key intermediates and allowed a complete mechanistic description to be presented, including off-cycle inhibitory processes, the source of amine and organoboron reactivity issues, and the origin of competing oxidation/protodeboronation side reactions. Identification of key mechanistic events has allowed the development of a simple solution to these issues: manipulating Cu(I) → Cu(II) oxidation and exploiting three synergistic roles of boric acid has allowed the development of a general catalytic Chan-Lam amination, overcoming long-standing and unsolved amine and organoboron limitations of this valuable transformation.
- Vantourout, Julien C.,Miras, Haralampos N.,Isidro-Llobet, Albert,Sproules, Stephen,Watson, Allan J. B.
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supporting information
p. 4769 - 4779
(2017/04/11)
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