- 'On-Water' Multicomponent Reaction for the Diastereoselective Synthesis of Functionalized Tetrahydropyridines and Mechanistic Insight
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An ecofriendly approach for the synthesis of highly substituted tetrahydropyridines by an 'on-water' multicomponent reaction has been demonstrated. The use of water as the reaction medium is essential under the catalytic influence of a surfactant. The use of a variety of anionic, cationic, and non-ionic surfactants in water was examined and the reaction was successfully catalyzed by anionic surfactants sodium dioctyl sulfosuccinate (SDOSS) and sodium dodecyl sulfate (SDS), with the former being superior. The use of an organic solvent together with a catalytic amount of sodium dioctyl sulfosuccinate to form homogeneous conditions afforded inferior yields and highlighted the specific role of water through the creation of microreactors at the water surfactant interface. A mechanistic insight for the five-component reaction leading to the formation of tetrahydropyridines is provided invoking a tandem inter- and intramolecular Mannich reaction pathway.
- Parikh, Naisargee,Roy, Sudipta Raha,Seth, Kapileswar,Kumar, Asim,Chakraborti, Asit K.
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- MnOX supported on a TiO2@SBA-15 nanoreactor used as an efficient catalyst for one-pot synthesis of imine by oxidative coupling of benzyl alcohol and aniline under atmospheric air
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In the present study, a mesoporous silica (SBA-15) encapsulated TiO2 nanoreactor is used as a support for MnOx and this MnOx/TiO2@SBA-15 acts as a catalyst for the one-pot synthesis of imine by oxidative coupling between benzyl alcohol and aniline in the presence of atmospheric air. To understand the properties, the catalysts were characterized by several analytical techniques, namely, N2 adsorption-desorption isotherm, small angle X-ray scattering (SAXS), wide angle X-ray diffraction, high resolution transmission electron microscopy (HRTEM), H2-temperature programmed reduction (H2-TPR), O2-temperature programmed oxidation (O2-TPO) and NH3-temperature programmed desorption (NH3-TPD). The pore encapsulation process by SBA-15 causes TiO2 to be in a highly dispersed state, and this highly dispersed TiO2 makes maximum contact with the MnOx species as well as the reactant molecules. The reaction was carried out at atmospheric pressure with equimolar amounts of substrates without additives in the presence of atmospheric air. The yield and selectivity of imines vary with the MnOx and TiO2 loading. The 7.5 wt% MnOx loaded TiO2@SBA-15 (5 wt% TiO2) nanoreactor showed the highest catalytic activity. With the increase in weak acid sites and the oxygen activation ability of the prepared catalyst, the conversion and selectivity of the desired product reached 96% and 97%, respectively. The investigation of the reaction mechanism suggests that there is a synergistic effect between highly dispersed TiO2 and MnOx, which improves the reactant conversion and the selectivity of the desired product (N-benzylideneaniline) and also the prepared catalyst shows excellent recyclability up to the 10th cycle. The recyclability and hot filtration study confirms the true heterogeneity of the prepared catalyst during imine synthesis. The heterogeneity of the prepared catalyst, the avoidance of any noble metal and the utilization of air as an oxidizing agent represent an efficient, green reaction pathway for imine synthesis.
- Mandal, Sandip,Maity, Sudip,Saha, Sujan,Banerjee, Biplab
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- Palladium-catalyzed tandem cyclization of fluorinated imidoyl chlorides with 2-bromophenylboronic acid: Synthesis of 6-fluoroalkyl-phenanthridines
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An efficient method has been developed to synthesize 6-fluoroalkyl-phenanthridines via the palladium-catalyzed tandem cyclization of fluorinated imidoyl chlorides with 2-bromophenylboronic acid. This methodology facilitates the rapid synthesis of 6-fluoroalkyl-phenanthridines through dual C–C bond formation in an oxidant-free one-pot manner.
- Bao, Yinwei,Wang, Zhuo,Chen, Chen,Zhu, Bolin,Wang, Yuebo,Zhao, Jinghui,Gong, Jinyu,Han, Mengya,Liu, Chang
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- Postsynthetic modification of an imine-based microporous organic network
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A highly cross-linked microporous organic network with imine linkers was prepared by condensation of tetrakis(4-aminophenyl)methane with terephthaldehyde. Gas adsorption studies indicate that the material exhibits permanent microporosity, and guest exchan
- Kerneghan, Phillip A.,Halperin, Shira D.,Bryce, David L.,Maly, Kenneth E.
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- High Catalytic Activity of C60Pdn Encapsulated in Metal–Organic Framework UiO-67, for Tandem Hydrogenation Reaction
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Metal nanoparticles (NPs) stabilized by MOFs are very promising for catalysis, whereas introduction of C60 into MOFs has been very rarely used, and there was no report for their cooperative catalysis in organic syntheses. In this work, C60@UiO-67 was synthesized by a one-pot method, so that C60 is uniformly distributed on UiO-67 in molecular form. Pd NPs coordinating with C60 have been successfully embedded into the framework. The obtained multifunctional C60Pdn@UiO-67 catalyst exhibits remarkable synergistic catalytic activity in cascade reactions under mild conditions, where UiO-67 affords Lewis acidity and C60Pdn offers higher hydrogenation activity relative to solely Pd NPs.
- Zheng, Deng-Yue,Zhou, Xue-Meng,Mutyala, Suresh,Huang, Xiao-Chun
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- Catalytic stereoselective Mannich reaction under solvent-free conditions
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Silicon tetrachloride catalyzed one-pot three-component Mannich reaction of cyclic ketones, aromatic aldehydes, and aromatic amine under solvent-free conditions affords the corresponding β-amino ketones with excellent yield and good to excellent anti-selectivity.
- Azizi, Najmadin,Baghi, Roya,Batebi, Elham,Bolourtchian, Seyed Mohammad
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- Simultaneous photocatalytic and catalytic activity of p–n junction NiO@anatase/rutile-TiO2 as a noble-metal free reusable nanoparticle for synthesis of organic compounds
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Photocatalytic and catalytic activity of NiO loaded on mixture of anatase/rutile phases of TiO2 nanoparticles were investigated for some organic reactions including selective oxidation of alcohols, synthesis of benzimidazoles and preparation of imines at room temperature. The p–n junction formed between NiO and TiO2 as well as difference between band gaps in anatase/rutile phases facilitated electron transfer to TiO2 and successfully promoted synthesis of compounds. The use of a reusable photocatalyst without noble metal co-catalysts, along with the mild reaction conditions and use of light energy, make this method as an environmentally benign and energy saving chemical procedure.
- Ziarati, Abolfazl,Badiei, Alireza,Mohammadi Ziarani, Ghodsi,Eskandarloo, Hamed
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- MnO2/graphene oxide: A highly efficient catalyst for imine synthesis from alcohols and amines
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α-MnO2 nanocrystals supported on graphene oxide (α-MnO2/GO) was prepared through a soft chemical route and evaluated for the first time as a novel, eco-friendly and efficient catalyst in the coupling reaction of alcohols and amines to imines. The well-organized α-MnO2/GO was characterized using various techniques. The results show that MnO2 nanocrystals are highly dispersed on the GO sheets and interconnected with each other, leading to large available surface area, which greatly enhances the catalytic performance of conventional MnO2. Under mild conditions, the catalyst exhibits excellent catalytic activity and selectivity with O2 serving as terminal oxidant. Various imines can be smoothly obtained in good to excellent yield. Importantly, the catalyst is easily recovered and can be reused six times with no significant loss of activity.
- Cheng, Shengxian,Ma, Xiaoxia,Hu, Yongke,Li, Bindong
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- Large Dimensional CeO2 Nanoflakes by Microwave-Assisted Synthesis: Lamellar Nano-Channels and Surface Oxygen Vacancies Promote Catalytic Activity
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Large nano-structured flakes of CeO2 (20–80 nm in thickness, up to 5.6 μm in diameter) were synthesized by a combination of microwave (MW), ultraviolet (UV) and ultrasound (US), with or without pressure (P). The CeO2 structures were systematically examined by XRD, SEM, N2 sorption, HRTEM, XPS, Raman and H2-TPR. The synthesized CeO2 nanoflakes were composed by 3.0–7.5 nm nanoparticles with the (111) surface exposed, and laminated to nanoflakes with 3.42–3.85 nm nano-channels in between. MW-assisting was beneficial to form a higher surface Ce3+/(Ce3++Ce4+) ratio and surface oxygen vacancies during short synthesis procedure. A Raman peak at 480 cm?1 correlating with bulk Ce3+ was detected. H2-TPR found MW and MW+P had more surface Ce3+ (surface oxygen vacancies). CO oxidation and imine conversion proved that MW+P was the optimum condition to produce highly active CeO2 nanoflakes. The much better catalytic performance than CeO2 from solvothermal preparation, due to the larger channel gap (3.85 nm),a higher Ce3+/(Ce3++Ce4+) ratio (32 %) and more surface oxygen vacancies on the particles of the organized flake structures.
- Ding, Huihui,Yang, Jingxia,Ma, Shuyi,Yigit, Nevzat,Xu, Jingli,Rupprechter, Günther,Wang, JinJie
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- Combined catalytic action of supported Cu and Au in imine production from coupled benzyl alcohol and nitrobenzene reactions
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The feasibility of continuous gas phase coupling of benzyl alcohol dehydrogenation with nitrobenzene hydrogenation for imine (N-benzylideneaniline) synthesis over mixtures of Cu/SiO2 and (TiO2, MgO) supported Au catalysts has been established. The catalysts were characterised in terms of specific surface area, pore volume, TPR, H2 chemisorption, STEM, XPS and TGA-DSC analysis. Au/TiO2 prepared by deposition-precipitation exhibited a narrower particle size distribution (1–6 nm) and smaller mean (3.2 nm) than Au/MgO (1–15 nm, mean = 7.7 nm) prepared by impregnation. Dehydrogenation of benzyl alcohol (to benzaldehyde) over Cu/SiO2 delivered a (ten-fold) higher rate than supported Au and Au/TiO2 exhibited a higher H2 chemisorption capacity and greater (by a factor of ten) nitrobenzene hydrogenation rate than Cu/SiO2 and Au/MgO. Inefficient hydrogen utilisation is demonstrated for the cross-coupling reaction over Cu/SiO2 alone and a temporal activity loss is linked to carbonaceous (benzoate) deposition (on the basis of XPS and TGA-DSC analysis). Incorporation of Au/TiO2 (and Au/MgO) with Cu/SiO2 increased the imine formation rate and H2 utilisation efficiency. The combination of Au/TiO2 with Cu/SiO2 served to circumvent Cu/SiO2 deactivation, resulting in enhanced stability with a four-fold increase in imine production and full H2 utilisation at Cu/Au = 10.
- Li, Maoshuai,Cárdenas-Lizana, Fernando,Keane, Mark A.
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- Thermal Cyclisation Reactions of Vinylogous Aminomethylene Meldrum's Acid Derivatives
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Flash vacuum pyrolysis of vinylogous aminomethylene derivatives of Meldrum's acid leads to new cyclisation reactions; one additional double bond results in the formation of 1H-azepin-3(2H)-ones, while two additional double bonds lead to benzamide derivatives.
- McNab, Hamish,Monahan, Lilian C.,Gray, Thomas
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- An infrared study of the photoisomerization of N-benzylideneaniline
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The infrared spectra of Nujol solutions and thin polycrystalline films of N-benzylideneaniline have been investigated.The 313 nm irradiation of ambient temperature samples produces no observable changes in the infrared spectra, however, similar irradiatio
- Lewis, J. W.,Sandorfy, C.
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- A DFT and experimental study of the spectroscopic and hydrolytic degradation behaviour of some benzylideneanilines
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The spectroscopic and hydrolytic degradation behaviour of some N-benzylideneanilines are investigated experimentally and theoretically via high quality density function theoretical (DFT) modelling techniques. Their absorption and vibrational spectra, accurately predicted by DFT calculations, are highly dependent on the nature of the substituents on the aromatic rings, hence, though some of their spectroscopic features are similar, energetic differences exist due to differences in their electronic structures. Whereas the o-hydroxy aniline derived adducts undergo hydrolysis via two pathways, the most energetically economical of which is initiated by a fast enthalpy driven hydration, over a conservative free energy (ΔG?) barrier of 53 kJ mol?1, prior to the rate limiting entropy controlled lysis step which occurs via a conservative barrier of ca.132 kJ mol?1, all other compounds hydrolyse via a slower two-step pathway, limited by the hydration step. Barriers heights for both pathways are controlled primarily by the structure and hence, stability of the transition states, all of which are cyclic for both pathways.
- Nelson, Peter N.,Robertson, Tahjna I.
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- Hydroborative reduction of amides to amines mediated by La(CH2C6H4NMe2-: O)3
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The deoxygenative reduction of amides to amines is a great challenge for resonance-stabilized carboxamide moieties, although this synthetic strategy is an attractive approach to access the corresponding amines. La(CH2C6H4NMe2-o)3, a simple and easily accessible lanthanide complex, was found to be highly efficient not only for secondary and tertiary amide reduction, but also for the most challenging primary reduction with pinacolborane. This protocol exhibited good tolerance for many functional groups and heteroatoms, and could be applied to gram-scale synthesis. The active species in this catalytic cycle was likely a lanthanide hydride.
- Gong, Mingliang,Guo, Chenjun,Luo, Yunjie,Xie, Hongzhen,Zhang, Fangcao
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p. 779 - 791
(2022/01/22)
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- Ammonium iodide-catalyzed radical-mediated tandem cyclization of aromatic aldehydes, arylamines and 1,4-dioxane
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We have developed a novel approach for the construction of 2-((2-arylquinolin-4-yl)oxy)ethan-1-ol derivatives by an NH4I-catalyzed radical-mediated tandem cyclization of three components including aromatic aldehydes, arylamines and 1,4-dioxane.
- Deng, Jiyong,Liao, Yunfeng,Qi, Hongrui,Tao, Qiang,Xie, Yanjun,Yan, Yiyan,Yi, Bing,Zhang, Weijie
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p. 959 - 965
(2022/02/03)
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- Azetidinimines as a novel series of non-covalent broad-spectrum inhibitors of β-lactamases with submicromolar activities against carbapenemases KPC-2 (class A), NDM-1 (class B) and OXA-48 (class D)
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The occurrence of resistances in Gram negative bacteria is steadily increasing to reach extremely worrying levels and one of the main causes of resistance is the massive spread of very efficient β-lactamases which render most β-lactam antibiotics useless. Herein, we report the development of a series of imino-analogues of β-lactams (namely azetidinimines) as efficient non-covalent inhibitors of β-lactamases. Despite the structural and mechanistic differences between serine-β-lactamases KPC-2 and OXA-48 and metallo-β-lactamase NDM-1, all three enzymes can be inhibited at a submicromolar level by compound 7dfm, which can also repotentiate imipenem against a resistant strain of Escherichia coli expressing NDM-1. We show that 7dfm can efficiently inhibit not only the three main clinically-relevant carbapenemases of Ambler classes A (KPC-2), B (NDM-1) and D (OXA-48) with Ki's below 0.3 μM, but also the cephalosporinase CMY-2 (class C, 86% inhibition at 10 μM). Our results pave the way for the development of a new structurally original family of non-covalent broad-spectrum inhibitors of β-lactamases.
- Romero, Eugénie,Oueslati, Saoussen,Benchekroun, Mohamed,D'Hollander, Agathe C.A.,Ventre, Sandrine,Vijayakumar, Kamsana,Minard, Corinne,Exilie, Cynthia,Tlili, Linda,Retailleau, Pascal,Zavala, Agustin,Elisée, Eddy,Selwa, Edithe,Nguyen, Laetitia A.,Pruvost, Alain,Naas, Thierry,Iorga, Bogdan I.,Dodd, Robert H.,Cariou, Kevin
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supporting information
(2021/04/19)
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- Convenient and Reusable Manganese-Based Nanocatalyst for Amination of Alcohols
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The development of new sustainable nanocatalytic systems for green chemical synthesis is a growing area in chemical science. Herein, a reusable heterogeneous N-doped graphene-based manganese nanocatalyst (Mn@NrGO) for selective N-alkylation of amines with alcohols is described. Mechanistic studies illustrate that the catalytic reaction follows a domino dehydrogenation-condensation-hydrogenation sequence of alcohols and amines with the formation of water as the sole by-product. The scope of the reaction is extended to the synthesis of pharmaceutically important N-alkylated amine intermediates. The heterogeneous nature of the catalyst made it easy to separate for long-term performance, and the recycling study revealed that the catalyst was robust and retained its activity after several recycling experiments.
- Subaramanian, Murugan,Ramar, Palmurukan M.,Sivakumar, Ganesan,Kadam, Ravishankar G.,Petr, Martin,Zboril, Radek,Gawande, Manoj B.,Balaraman, Ekambaram
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p. 4334 - 4341
(2021/08/25)
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- A carbon dioxide-promoted three-component Strecker reaction
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A three-component Strecker reaction of aldehydes, amines and KCN has been performed for the first time in supercritical carbon dioxide. In the proposed procedure, non-toxic and non-flammable carbon dioxide acts not only as an environmentally benign reaction medium but also as a reaction promoter via in situ formation of carbonic acid which provides a gradual release of the true cyanating agent (HCN) from available KCN. The reaction conditions (pressure, temperature, and concentrations of reagents) were optimized, and various aromatic and aliphatic amines and aldehydes were transformed into valuable α-amino nitriles including prospective pharmacological substances. The equimolar amount of used cyanogen reagent, carrying out the process in a sealed autoclave in a 'green' solvent medium under mild conditions (90 bar, 35 °C) along with the high yields of products and the scalability of the developed procedure make it suitable for sustainable industrial applications. This journal is
- Fauziev, Ruslan V.,Ivanov, Roman E.,Kuchurov, Ilya V.,Zlotin, Sergei G.
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p. 10137 - 10144
(2021/12/24)
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- Construction of Flexible Amine-linked Covalent Organic Frameworks by Catalysis and Reduction of Formic Acid via the Eschweiler–Clarke Reaction
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Compared to the current mainstream rigid covalent organic frameworks (COFs) linked by imine bonds, flexible COFs have certain advantages of elasticity and self-adaptability, but their construction and application are greatly limited by the complexity in s
- Zhang, Meicheng,Li, Yang,Yuan, Wenli,Guo, Xinghua,Bai, Chiyao,Zou, Yingdi,Long, Honghan,Qi, Yue,Li, Shoujian,Tao, Guohong,Xia, Chuanqin,Ma, Lijian
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supporting information
p. 12396 - 12405
(2021/04/30)
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- Deep eutectic solvents as H2-sources for Ru(II)-catalyzed transfer hydrogenation of carbonyl compounds under mild conditions
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The employment of easily affordable ruthenium(II)-complexes as pre-catalysts in the transfer hydrogenation of carbonyl compounds in deep eutectic media is described for the first time. The eutectic mixture tetrabutylammonium bromide/formic acid = 1/1 (TBABr/HCOOH = 1/1) acts both as reaction medium and hydrogen source. The addition of a base is required for the process to occur. An extensive optimization of the reaction conditions has been carried out, in terms of catalyst loading, type of complexes, H2-donors, reaction temperature and time. The combination of the dimeric complex [RuCl(p-cymene)-μ-Cl]2 (0.01–0.05 eq.) and the ligand dppf (1,1′-ferrocenediyl-bis(diphenylphosphine)ferrocene) in 1/1 molar ratio has proven to be a suitable catalytic system for the reduction of several and diverse aldehydes and ketones to their corresponding alcohols under mild conditions (40–60 °C) in air, showing from moderate to excellent tolerability towards different functional groups (halogen, cyano, nitro, phenol). The reduction of imine compounds to their corresponding amine derivatives was also studied. In addition, the comparison between the results obtained in TBABr/HCOOH and in organic solvents suggests a non-innocent effect of the DES medium during the process.
- Cavallo, Marzia,Arnodo, Davide,Mannu, Alberto,Blangetti, Marco,Prandi, Cristina,Baratta, Walter,Baldino, Salvatore
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supporting information
(2021/02/22)
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- Room Temperature Acid-Free Greener Synthesis of Imine Using Cobalt-Doped Manganese Tungstate
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Facile synthesis of an imine compound through a greener route is still a challenging task. Industrial processes rely on the age-old Schiff reaction for the synthesis of imine, which are reversible and nongreen from an environmental viewpoint. Herein, coba
- Mal, Diptangshu Datta,Pradhan, Debabrata
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- Ruthenium-Catalyzed Dehydrogenation Through an Intermolecular Hydrogen Atom Transfer Mechanism
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The direct dehydrogenation of alkanes is among the most efficient ways to access valuable alkene products. Although several catalysts have been designed to promote this transformation, they have unfortunately found limited applications in fine chemical synthesis. Here, we report a conceptually novel strategy for the catalytic, intermolecular dehydrogenation of alkanes using a ruthenium catalyst. The combination of a redox-active ligand and a sterically hindered aryl radical intermediate has unleashed this novel strategy. Importantly, mechanistic investigations have been performed to provide a conceptual framework for the further development of this new catalytic dehydrogenation system.
- Huang, Lin,Bismuto, Alessandro,Rath, Simon A.,Trapp, Nils,Morandi, Bill
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supporting information
p. 7290 - 7296
(2021/03/01)
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- Aromatic Dendrimers Bearing 2,4,6-Triphenyl-1,3,5-triazine Cores and Their Photocatalytic Performance
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The synthesis of two novel aromatic dendrimers structurally derived from 1,3,5-tri[1,3-diphenyl(phenyl-5-yl)phenyl-4′-yl]benzene and bearing 2,4,6-triphenyl-1,3,5-triazine cores is reported. The obtained dendrimers were used for the OLEDs construction, as well as in the role of innovative photocatalysts for the very efficient and selective oxidation of various benzylamines to respective N-benzylidene benzylamines under mild conditions.
- Cyniak, Jakub S.,Kasprzak, Artur
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p. 6855 - 6862
(2021/05/29)
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- Efficient imine synthesisviaoxidative coupling of alcohols with amines in an air atmosphere using a mesoporous manganese-zirconium solid solution catalyst
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Direct oxidative coupling of alcohols with amines using a non-precious metal oxide catalyst under mild conditions is highly desirable for imine synthesis. In this work, a mesoporous Mn1ZrxOysolid solution catalyst prepared by a co-precipitation method showed excellent catalytic performance in imine synthesis from primary alcohols and amines without base additives in an air atmosphere. XRD, N2physisorption, H2-TPR, O2-TPD, EPR and XPS were comprehensively used to unravel its structural, redox and amphoteric properties that closely depended on the interaction between MnOyand ZrO2with a variable Zr ratio. The Mn1Zr0.5Oycatalyst presented the highest fractions of Mn3+ions and reactive oxygen species on the surface, and the highest concentrations of acidic-basic sites, which were disclosed to play important roles in activating alcohols and molecular O2in the rate-determining step. In the model reaction of oxidative coupling of benzyl alcohol with aniline, such enhanced features of the Mn1Zr0.5Oycatalyst can promote the intrinsic catalytic activity (iTOF of 1.87 h?1) and boost benzylideneaniline formation (5.56 mmol gcat.?1h?1) based on a >99% yield at 80 °C respectively at a fast response. It can also work effectively at a room temperature of 30 °C, as well as for the gram-grade synthesis. This is one of the best results among all the MnOy-based catalysts in the literature. Moreover, this catalyst showed good stability and a wide substrate scope with good to excellent yields of imines.
- Wu, Shipeng,Zhang, Hao,Cao, Qiue,Zhao, Qihua,Fang, Wenhao
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p. 810 - 822
(2021/02/26)
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- Highly efficient and selective one-pot tandem imine synthesis via amine-alcohol cross-coupling reaction catalysed by chromium-based MIL-101 supported Au nanoparticles
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One-pot tandem synthesis of imines from alcohols and amines is regarded as an effective, economic and green approach under mild conditions. In this work, Au nanoparticles (NPs) dispersed on MIL-101 (Au/MIL-101) were demonstrated as highly active and selective bifunctional heterogeneous catalyst for production of various imine derivatives with excellent yields, via amine-alcohol cross-coupling reaction at 343 K in an open flask under an Ar atmosphere. Various physicochemical techniques, including inductively coupled plasma optical emission spectroscopy (ICP-OES), powder X-ray diffraction (P-XRD), X-ray photoelectron spectroscopy (XPS) transmission electron microscopy (TEM) and N2 adsorption-desorption, were used to characterize of the Au/MIL-101 catalyst. The obtained bifunctional catalyst is highly active and selective towards one-pot imine formation and exhibited the highest TOF (30.15-51.47 h?1) among all the ever-reported MOF-supported Au catalysts. The reaction mechanism of the imine formation from alcohol and amine over Au/MIL-101 catalyst was proposed. Mechanism experiment results demonstrate that Au NPs highly effective in activating oxidation of benzyl alcohol to benzaldehyde while the Lewis acid sites on MIL-101 catalyzed the second condensation step without interfering with the oxidation step. As a result, the excellent catalytic performance of Au/MIL-101 can be ascribed to the synergistic effect between Au NPs with Lewis acid sites in MIL-101.
- Gülcan, Mehmet,Gumus, Ilkay,Karatas, Yasar,Ruzgar, Adem
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- Ionic-Liquid-Catalyzed Synthesis of Imines, Benzimidazoles, Benzothiazoles, Quinoxalines and Quinolines through C?N, C?S, and C?C Bond Formation
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We report the tetramethyl ammonium hydroxide catalyzed oxidative coupling of amines and alcohols for the synthesis of imines under metal-free conditions by utilizing oxygen from air as the terminal oxidant. Under the same conditions, with ortho-phenylene diamines and 2-aminobenzenethiols the corresponding benzimidazoles and benzothiazoles were obtained. Quinoxalines were obtained from ortho-phenylene diamines and 1-phenylethane-1,2-diol, the conditions were then extended to the synthesis of quinoline building blocks by reaction of 2-amino benzyl alcohols either with 1-phenylethan-1-ol or acetophenone derivatives. The formation of C?N, C?S and C?C bonds was achieved under metal-free conditions. A broad range of amines (aromatic, aliphatic, cyclic and heteroaromatic) as well as benzylic alcohols including heteroaryl alcohols reacted smoothly and provided the desired products. The mild reaction conditions, commercially available catalyst, metal-free, good functional-group tolerance, broad range of products (imines, benzimidazoles, benzothiazoles, quinoxalines and quinolines) and applicability at gram scale reactions are the advantages of the present strategy.
- Adimurthy, Subbarayappa,Badhani, Gaurav,Joshi, Abhisek
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p. 6705 - 6716
(2021/12/31)
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- Vanadium-and chromium-catalyzed dehydrogenative synthesis of imines from alcohols and amines
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Vanadium(IV) tetraphenylporphyrin dichloride and chromium(III) tetraphenylporphyrin chloride have been developed as catalysts for the acceptorless dehydrogenation of alcohols. The catalysts have been applied to the direct synthesis of imines in overall good yields from a variety of alcohols and amines. The transformations are proposed to proceed by metal?ligand bifunctional pathways with an outer-sphere transfer of two hydrogen atoms from the alcohol to the metal porphyrin complexes. The results show that vanadium and chromium catalysts can also be employed for the dehydrogenation of alcohols with the release of hydrogen gas, and they may represent valuable alternatives to other catalysts based on Earth-abundant metals.
- Madsen, Robert,Miao, Yulong,Samuelsen, Simone V.
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supporting information
p. 1328 - 1335
(2021/05/29)
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- Nitrogen-modified graphene as a metal-free carbocatalyst for the solvent-free oxidative homo- and heterocoupling of amines
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In this study, graphene oxide (GO) has been prepared using Hammers’ method and the produced GO was converted to nitrogen-modified GO (NGO) using hydrothermal reaction with ammonia and hydrazine. The morphology of the product was confirmed with FESEM images and XRD, TEM, Raman, TGA, EDS, BET and FTIR analyses were employed to study the structure and properties of the product. The produced NGO has been employed as a catalyst for oxidative coupling of amines to imines. The reaction was carried out at 110?°C, using 4 wt% of catalyst (versus the used amine), oxygen gas as oxidative agent, solvent-free condition in 4?h with 80% yield. To determine the versatility of the reaction, different derivatives of amines such as benzylamine, phenyl hydrazine, aniline, ethylenediamine, ethanol amine and homoveratrylamine have been examined in this reaction and successfully converted to the related imines via heterocoupling reactions. Finally, the recyclability of the reaction was investigated and the results showed only 10% decreasing in the yield after 6 runs.
- Ganbari, Alireza,Tavakol, Hossein
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- Fe2Mn(μ3-O)(COO)6 Cluster Based Stable MOF for Oxidative Coupling of Amines via Heterometallic Synergy
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The direct catalytic oxidative coupling of amines is one of the attracting methods for the synthesis of a variety of pharmaceutical or industrial needed imines. Numerous earth-abundant manganese based salts, oxides, and complexes have been applied in this reaction. However, these compounds suffered from difficult separation, large catalyst loading, complicated reactivation or indeterminate activity. Considering the facts that metal-organic frameworks (MOFs) with crystalline structure, precise composition, and enormous surface area have superior performance in heterogeneous catalytic reactions, herein, we introduced Mn into [Fe3(μ3-O)(CH3COO)6], one of the precursors for the preparation of stable MOFs, and got [Fe2Mn(μ3-O)(CH3COO)6] cluster. After ligand replacement with biphenyl-3,4’,5-tricarboxylic acid (BPTC), heterometallic cluster-based [Fe2Mn(μ3-O)(BPTC)2(DMF)2(H2O)] (1) was obtained. As expected, 1 is stable and able to catalyze the homo- or cross-coupling of amines effectively and selectively with 0.9 mol% catalyst loading at room temperature. Control experiments indicated that the catalytic activity of 1 mainly stems from Mn sites and that Fe synergistically contributes to the stability. Additionally, 1 is recyclable and can be reused easily for at least 8 runs without obvious decrease in catalytic ability. To our knowledge, 1 should be the first heterometallic cluster-based MOF with defined structure suitable for the synthesis of diverse imines from oxidative coupling of amines under mild conditions, which may shed light on the easy preparation of effective heterogeneous catalysts for organic synthesis.
- Wang, Ying-Xia,Wang, Hui-Min,Meng, Pan,Song, Dong-Xia,Qi, Zhikai,Zhang, Xian-Ming
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p. 2983 - 2989
(2021/08/30)
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- Method for realizing oxidative dehydrogenation of nitrogen-containing heterocyclic ring by using biomass-based carbon material
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The invention provides a method for realizing oxidative dehydrogenation of a nitrogen-containing heterocyclic ring by using a biomass-based carbon material, and belongs to the field of organic synthesis. According to the method, the raw materials of the biomass-based carbon material comprise wheat, sorghum, rice, corn straw, wheat straw, peanut shells, sesame shells, bean shells and the like, and are crushed and then ground into powder, the powder is fully mixed with an inorganic alkali, and calcination is performed in an inert gas atmosphere to prepare the biomass-based carbon material; and by using air as an oxygen source, at a temperature of 50-120 DEG C, oxidative dehydrogenation of nitrogen-containing heterocyclic compounds to synthesize quinoline compounds, isoquinoline compounds, acridine compounds, quinazoline compounds, indole compounds, imine compounds, and even quinoline compounds with pharmaceutical activity can be achieved. According to the present invention, easily available wheat flour is adopted as a raw material to prepare a non-metal catalyst, the alkali is not added during the reaction process, and a remarkable industrial application prospect is achieved.
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Paragraph 0010-0011; 0042-0043
(2021/06/26)
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- Direct synthesis of imines from nitro compounds and biomass-derived carbonyl compounds over nitrogen-doped carbon material supported Ni nanoparticles
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The selective synthesis of imines from biomass-derived chemicals over heterogeneous non-noble metal catalysts is of great importance for organic transformation. Herein, non-noble heterogeneous nitrogen-doped carbon supported Ni catalysts (abbreviated as Ni/CN-MgO-T, whereTrepresents the pyrolysis temperature) have been facilely prepared from the simple pyrolysis of Ni precursors and biomass, and Ni/CN-MgO-600 with the smallest size of Ni nanoparticles demonstrated the highest catalytic activity. The reductive coupling of nitroarenes and carbonyl compounds could be performed under mild conditions (80 °C, and 10 bar H2), affording structurally-diverse imines with high to excellent yields (84.2-98.1%). Thanks to the mild reaction conditions, the developed method showed good tolerance to other functional groups such as nitriles, halogen and vinyl groups.
- Li, Bo,Wang, Yanxin,Chi, Quan,Yuan, Ziliang,Liu, Bing,Zhang, Zehui
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p. 4464 - 4471
(2021/03/15)
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- Chemoselective synthesis of imine and secondary amine from nitrobenzene and benzaldehyde by Ni3Sn2 alloy catalyst supported on TiO2
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Ni3Sn2/TiO2 alloy catalyst prepared by hydrothermal method was applied for the direct one-pot reductive imination of benzaldehyde with nitrobenzene in the presence of H2 gas as a reducing agent. A desired imine, benzylideneaniline, was produced in an excellent yield of 90% without the formation of any by-products. This is due to the chemoselective molecular recognition of Ni3Sn2 alloy nanoparticles supported on TiO2 for the nitro group over the carbonyl group. By prolonging the reaction time, the desired imine was converted into the corresponding secondary amine, N-phenylbenzylamine, with a remarkably high yield of 80% through the catalytic hydrogenation of the C[dbnd]N bond. Finally, we demonstrated that it was easy to reuse the catalyst up to five times.
- Yamanaka, Nobutaka,Hara, Takayoshi,Ichikuni, Nobuyuki,Shimazu, Shogo
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- Highly chemoselective synthesis of imine over Co/Zn bimetallic MOFs derived Co3ZnC-ZnO embed in carbon nanosheet catalyst
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One-pot direct synthesis of imines via reductive amination of nitroarenes with aromatic aldehydes remains a great challenge due in part to its over-hydrogenation of imines to secondary amines. Herein, a novel Co3ZnC and ZnO supported on N-doped carbon nanosheet catalyst with the thickness of ca. 5.0 nm was fabricated through the direct pyrolysis of a Co/Zn bimetallic MOFs at 500 °C (named as Co3ZnC-ZnO/NC-500). Surprisingly, the developed Co3ZnC-ZnO/NC-500 catalyst delivers 99.9 % conversion of nitrobenzene and 98.5 % selectivity to N-benzylideneaniline in one-pot reductive amination of nitrobenzene with benzaldehyde. Various characterizations (including as SEM, XRD, TEM, AFM, XPS, Raman and N2 adsorption–desorption) have revealed that the generated small size of Co3ZnC alloy, abundant structural defects, larger specific surface area (105.5 m2·g?1) as well as more basic sites are responsible for the outstanding catalytic activity of Co3ZnC-ZnO/NC-500 catalyst for tandem reaction. Moreover, the Co3ZnC-ZnO/NC-500 catalyst exhibits high stability during the recycling experiments without the loss of its catalytic activity. Notably, the results of contrast experiments have demonstrated that the intentional introduction of ZnO in Co3ZnC-ZnO/NC-500 catalyst plays a key role in the selectivity to N-benzylideneaniline in the tandem reaction. This study provides a new guideline for designing tandem catalysts with high selectivity.
- Li, Guangming,Li, Jingfang,Li, Weizuo,Li, Xuewei,Mao, Guijie,She, Wei,Wang, Jing
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- BF3·Et2O as a metal-free catalyst for direct reductive amination of aldehydes with amines using formic acid as a reductant
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A versatile metal- and base-free direct reductive amination of aldehydes with amines using formic acid as a reductant under the catalysis of inexpensive BF3·Et2O has been developed. A wide range of primary and secondary amines and diversely substituted aldehydes are compatible with this transformation, allowing facile access to various secondary and tertiary amines in high yields with wide functional group tolerance. Moreover, the method is convenient for the late-stage functionalization of bioactive compounds and preparation of commercialized drug molecules and biologically relevant N-heterocycles. The procedure has the advantages of simple operation and workup and easy scale-up, and does not require dry conditions, an inert atmosphere or a water scavenger. Mechanistic studies reveal the involvement of imine activation by BF3and hydride transfer from formic acid.
- Fan, Qing-Hua,Liu, Xintong,Luo, Zhenli,Pan, Yixiao,Xu, Lijin,Yang, Ji,Yao, Zhen,Zhang, Xin
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supporting information
p. 5205 - 5211
(2021/07/29)
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- Continuous flow heterogeneous catalytic reductive aminations under aqueous micellar conditions enabled by an oscillatory plug flow reactor
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Despite the fact that continuous flow processing exhibits well-established technical advances, aqueous micellar chemistry, a field that has proven extremely useful in shifting organic synthesis to sustainable water-based media, has mostly been explored under conventional batch-based conditions. This is particularly because of the fact that the reliable handling of slurries and suspensions in flow has been considered as a significant technical challenge. Herein, we demonstrate that the strategic application of an oscillatory plug flow reactor enables heterogeneous catalytic reductive aminations in aqueous micellar media enhancing mass transport and facilitating process simplicity, stability and scalability. The micellar flow process enabled a broad range of substrates, including amino acid derivatives, to be successfully transformed under reasonably mild conditions utilizing only very low amounts of Pd/C as a readily available heterogeneous catalyst. The preparative capabilities of the process along with the recyclability of the heterogenous catalyst and the aqueous reaction media were also demonstrated. This journal is
- ?tv?s, Sándor B.,Buchholcz, Balázs,Darvas, Ferenc,Kappe, C. Oliver,Novák, Zoltán,Sipos, Gellért,Wernik, Michaela
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supporting information
p. 5625 - 5632
(2021/08/16)
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- Cobalt-Catalyzed Deoxygenative Hydroboration of Nitro Compounds and Applications to One-Pot Synthesis of Aldimines and Amides
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The commercially available and bench-stable Co(acac)2 ligated with bis[(2-diphenylphosphino)phenyl] ether (dpephos) was employed for selective room temperature hydroboration of nitro compounds with HBPin (TOF up to 4615 h?1), tolerating halide, hydroxy, amino, ether, ester, lactone, amide and heteroaromatic functionalities. These reactions offered a direct access to a variety of N-borylamines RN(H)BPin, which were in situ treated with aldehydes and carboxylic acids to produce a series of aldimines and secondary carboxamides without the need for dehydrating and/or coupling reagents. Combination of these transformations in a sequential one-pot manner allowed for direct and selective synthesis of aldimines and secondary carboxamides from readily available and inexpensive nitro compounds.
- Gudun, Kristina A.,Hayrapetyan, Davit,Khalimon, Andrey Y.,Segizbayev, Medet,Slamova, Ainur,Zakarina, Raikhan
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- Stable Ni catalyst encapsulated in N-doped carbon nanotubes for one-pot reductive amination of nitroarenes with aldehydes
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A novel strategy involving a popping process and carbothermal reduction was developed to create a kind of stable nickel catalyst (Ni-NC). The popping process of the mixture being composed of carbon nitride (C3N4) and nickel nitrate decomposed the nickel nitrate into nickel (oxide) nanoparticles that afterwards functioned as catalyst to grow N-containing carbon nanotubes with carbon nitride as N-containing carbon source. Finally, the nickel catalyst possessed a special structure of nanoparticles encapsulated in N-doped carbon nanotubes. This special structure is helpful to prevent nickel nanoparticles from being oxidized in air for months so that the catalyst exhibits high stability in air atmosphere. As a practical application, this encapsulated nickel catalyst exhibited excellent catalytic activity and stability in one-pot cascade reaction involving nitro-reduction and reductive amination of nitroarenes.
- Cui, Penglei,Gao, Yongjun,Liu, Yaru,Shang, Ningzhao,Wang, Chun,Xu, Yuzhu
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- Tandem imine formationviaauto-hydrogen transfer from alcohols to nitro compounds catalyzed by a nanomagnetically recyclable copper catalyst under solvent-free conditions
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A direct imination reaction was developed by tandem reaction of alcohols and nitro compounds in the presence of Cu-isatin Schiff base-γ-Fe2O3as a nanomagnetically recyclable catalyst under solvent-free conditions. By this method, various imines were prepared in good to high yields from one-pot reaction of various alcohols (primary aromatic and aliphatic) and nitro compounds (aromatic and aliphatic)viaan auto-hydrogen transfer reaction. Use of an inexpensive and easily reusable catalyst, without requiring any additives or excess amounts of benzyl alcohol as the reaction solvent are the other advantages of this method. This catalytic system has the merits of cost effectiveness, environmental benignity, excellent recyclability and good reproducibility.
- Derakhshan, Seyed Ruhollah,Hosseini Moghadam, Hadis,Sansano, José Miguel,Sobhani, Sara
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p. 19121 - 19127
(2021/06/03)
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- Iron-Catalyzed Hydrogen Transfer Reduction of Nitroarenes with Alcohols: Synthesis of Imines and Aza Heterocycles
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A straightforward and selective reduction of nitroarenes with various alcohols was efficiently developed using an iron catalyst via a hydrogen transfer methodology. This protocol led specifically to imines in 30-91% yields, with a good functional group tolerance. Noticeably, starting from o-nitroaniline derivatives, in the presence of alcohols, benzimidazoles can be obtained in 64-72% yields when the reaction was performed with an additional oxidant, DDQ, and quinoxalines were prepared from 1,2-diols in 28-96% yields. This methodology, unprecedented at iron for imines, also provides a sustainable alternative for the preparation of quinoxalines and benzimidazoles.
- Wu, Jiajun,Darcel, Christophe
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p. 1023 - 1036
(2021/01/09)
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- Hydrogen Auto-transfer Synthesis of Quinoxalines from o-Nitroanilines and Biomass-based Diols Catalyzed by MOF-derived N,P Co-doped Cobalt Catalysts
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A Co-based heterogeneous catalyst supported on N,P co-doped porous carbon (Co@NCP) is prepared via a facile in-situ doping-carbonization method. The Co@NCP composite features a large surface area, high pore volume, high-density and strong basic sites. Furthermore, doping of P atoms can regulate the electronic density of Co. Therefore, Co@NCP exhibits good performance for the synthesis of quinoxalines from o-nitroanilines and biomass-derived diols under alkali-free conditions.
- Sun, Kangkang,Li, Dandan,Lu, Guo-Ping,Cai, Chun
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p. 373 - 381
(2020/12/09)
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- Selective Production of Secondary Amine by the Photocatalytic Cascade Reaction Between Nitrobenzene and Benzyl Alcohol over Nanostructured Bi2MoO6 and Pd Nanoparticles Decorated with Bi2MoO6
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The synthesis of secondary amine by the photoalkylation of nitrobenzene with benzyl alcohol using a simple light source and sunlight is a challenging task. Herein, a one-pot cascade protocol is employed to synthesize secondary amine by the reaction between nitrobenzene and benzyl alcohol. The one-pot cascade protocol involves four reactions: (a) photocatalytic reduction of nitrobenzene to aniline, (b) photocatalytic oxidation of benzyl alcohol to benzaldehyde, (c) reaction between aniline and benzaldehyde to form imine, and (d) photocatalytic reduction of imine to a secondary amine. The cascade protocol to synthesize secondary amine is accomplished using Bi2MoO6 and Pd nanoparticles decorated Bi2MoO6 catalysts. The surface characteristics, oxidation states, and elemental compositions of the materials are characterized by several physicochemical characterization techniques. Optoelectronic and photoelectrochemical measurements are carried out to determine the bandgap, band edge potentials, photocurrents, charge carrier's separation, etc. An excellent yield of secondary amine is achieved with simple household white LED bulbs. The catalyst also exhibits similar or even better activity in sunlight. The structure-activity relationship is established using catalytic activity data, control reactions, physicochemical, optoelectronic characteristics, and scavenging studies. Bi2MoO6 and Pd nanoparticles decorated Bi2MoO6 exhibit excellent photostability and recyclability. The simple catalyst design with a sustainable and economical light source for the synthesis of useful secondary amine from the nitrobenzene and benzyl alcohol would attract the researchers to develop similar catalytic protocols for other industrially important chemicals.
- Ghalta, Rajat,Kar, Ashish Kumar,Srivastava, Rajendra
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supporting information
p. 3790 - 3803
(2021/10/25)
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- Synthesis of an Fe-Pd bimetallic catalyst for: N -alkylation of amines with alcohols via a hydrogen auto-transfer methodology
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Hydrogen auto-transfer (HAT) or borrowing hydrogen (BH) methodology which combines dehydrogenation, intermediate reaction and hydrogenation, is recognized as an excellent strategy for one-pot synthesis from an economic and environmental point of view. Although much effort has been made on the development of catalysts for HAT reactions, harsh conditions, external base or large amounts of noble metals are still required in most reported catalysis systems, and thus the exploration of a highly efficient and recyclable heterogeneous catalyst remains meaningful. In this work, a novel bimetallic catalyst, Fe10Pd1/NC500 derived from bimetallic MOF NH2-MIL-101(Fe10Pd1), has been prepared, and the catalyst exhibits superior catalytic performance for the N-alkylation of amines with alcohols via a hydrogen auto-transfer methodology. High yields of the desired products were achieved at 120 °C with an alcohol/amine molar ratio of 2?:?1 and required no external additive or solvent. A distinct enhancement in catalytic performance is observed when compared with monometallic catalysts, which can be ascribed to the "synergistic effects"inside the bimetallic alloys. The N-doped carbon support has been revealed to provide the necessary basicity which avoids the requirement of an external base. Moreover, a wide substrate range and remarkable reusability have been shown by Fe10Pd1/NC500, and this work highlights new possibilities for bimetallic catalysts applied in sustainable chemistry.
- Wu, Peng-Yu,Lu, Guo-Ping,Cai, Chun
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p. 396 - 404
(2021/01/28)
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- Photocatalytic one-pot multidirectional N-alkylation over Pt/D-TiO2/Ti3C2: Ti3C2-based short-range directional charge transmission
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Visible-light-induced one-pot, multistep, and chemoselectivity adjustable reactions highlight the economical, sustainable, and green process. Herein, we report Pt nanoparticles dispersed on S and N co-doped titanium dioxide/titanium carbide (MXene) (3%Pt/
- Jiang, Heyan,Sheng, Meilin,Li, Yue,Kong, Shuzhen,Bian, Fengxia
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- One-Pot Synthesis of Schiff Bases by Defect-Induced TiO2- x-Catalyzed Tandem Transformation from Alcohols and Nitro Compounds
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Schiff bases that are generally formed from condensation reactions of aldehydes (or ketones) and amino groups could also be produced by a photodriven one-pot tandem reaction between alcohols and nitro compounds, in our case. Herein, TiO2-x porous cages derived from NH2-MIL-125 by a self-sacrificing template route are used to study the organic transformation and exhibit 100% conversion efficiency of nitrobenzene and 100% selectivity for Schiff bases in the system of benzyl alcohol (5 mL) and nitrobenzene (41 μL) upon light irradiation, but hydrogen by dehydrogenation of benzyl alcohol cannot be detected. Successful occurrence of the organic transformation is mainly attributed to Ti(III)-oxygen vacancy associates. Surface oxygen vacancy-related Ti(III) sites are responsible for binding with nitro groups, and low-coordinated Ti5c sites selectively adsorb hydroxyl groups of benzyl alcohol. The Ti(III) and oxygen vacancy associates capture photogenerated electrons for achievement of multielectron reduction of nitrobenzene and the subsequent Schiff base condensation reaction with the as-formed benzaldehyde.
- Chen, Liyong,Fang, Qiang,Shen, Xiaoshuang,Tong, Jing,Wang, Jinfeng,Wang, Yao,Zhang, Hui
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supporting information
p. 10715 - 10721
(2021/07/26)
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- Iron-catalyzed N-alkylation of aromatic amines via borrowing hydrogen strategy
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Earth-abundant transition metals could be used as a noble metal replacement in catalysis not only for different catalytic reactivity but environmentally benign methodology. We report here on the iron-catalyzed synthesis of N-alkylated amines via borrowing hydrogen strategy and differently functionalized aniline derivatives are alkylated in good yields.
- Chen, Hui,Wang, Qingfu,Liu, Tingting,Chen, Haitao,Zhou, Duo,Qu, Fengbo
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p. 877 - 884
(2021/02/16)
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- Easy and One-Step Synthesis of Ir Single Atom Doped PPy Nanoparticles for Highly Active N-Alkylation Reaction
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Single atoms are nowadays considered new catalysts offering a lot of advantages such as reduced cost and use of noble metals. Here, we report the catalytic activity towards N-alkylation reactions of single atoms (SACs) of iridium doped polypyrrole (Ir?PPy nanoparticles). The new nanocatalyst exhibits excellent behavior due to the combination of highly active SACs catalyst and the organic conductive support providing strong binding of single atoms and thus improved reusability and easiness to handle. In the presence of a low amount of Ir and of a suitable base, excellent activity (yield >99 %) and selectivity (>99 %) were obtained. In the optimized Ir condition (3 wt.% of Ir) an aniline conversion of about 99 %, with excellent selectivity, just after 600 min, was obtained. Recyclability tests show that the catalyst can be successfully recycled six times without significant catalyst activity loss.
- Iuliano, Mariagrazia,Sarno, Maria,Cirillo, Claudia,Ponticorvo, Eleonora,De Pasquale, Salvatore
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p. 644 - 653
(2021/02/03)
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- Ru(II)-NHC catalysed N-Alkylation of amines with alcohols under solvent-free conditions
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The reaction of [RuCl2(p-cymene)]2 with in situ prepared Ag-N-heterocyclic carbene (NHC) complexes yields a series of [RuCl2(p-cymene)(NHC)] complexes (2). All of the complexes have been characterised by elemental analysis, and 1H NMR and 13C NMR spectroscopies. These complexes have been tested for the N-alkylation of aromatic amines with arylmethyl alcohols under neat conditions in the presence of KOtBu at 120 °C. Compounds (2) are stable and have high catalytic/selective activity for the N-alkylation reactions of primary amines to afford secondary amines.
- Karaca, Emine ?zge,Dehimat, Zieneb Imene,Ya?ar, Sedat,Gürbüz, Nevin,Tebbani, Dahmane,?etinkaya, Bekir,?zdemir, ?smail
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- Amino-functionalized zirconium and cerium MOFs: Catalysts for visible light induced aerobic oxidation of benzylic alcohols and microwaves assisted N-Alkylation of amines
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Herein we report that mixed zirconium-cerium-MOFs with amino-functionalized linkers (2-amino-1,4-benzenedicarboxylate, BDC-NH2, and 4-aminonaphthalene-2,6-dicarboxylate, NDC-NH2) act as effective non-noble-metal-based heterogeneous c
- Iglesias, Marta,Pintado-Sierra, Mercedes,Rasero-Almansa, Antonia,Sánchez, Félix,Valverde-González, Antonio
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- Synthesis of 1-Pyrroline by Denitrogenative Ring Expansion of Cyclobutyl Azides under Thermal Conditions
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We herein report an efficient and systematic synthesis of 1-pyrrolines from cyclobutyl azides under thermal and neutral conditions. The reaction proceeded without any additional reagents, and nitrogen was generated as the sole by-product. Furthermore, the generated 1-pyrrolines could be continuously transformed into pyrroles, N-Boc-amines, and oxaziridines in an one-pot manner. (Figure presented.).
- Ban, Kazuho,Miki, Yuya,Sajiki, Hironao,Sawama, Yoshinari,Tomita, Naohito
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p. 3481 - 3484
(2021/06/17)
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- Highly economical and direct amination of sp3carbon using low-cost nickel pincer catalyst
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Developing more efficient routes to achieve C-N bond coupling is of great importance to industries ranging from products in pharmaceuticals and fertilizers to biomedical technologies and next-generation electroactive materials. Over the past decade, improvements in catalyst design have moved synthesis away from expensive metals to newer inexpensive C-N cross-coupling approaches via direct amine alkylation. For the first time, we report the use of an amide-based nickel pincer catalyst (1) for direct alkylation of amines via activation of sp3 C-H bonds. The reaction was accomplished using a 0.2 mol% catalyst and no additional activating agents other than the base. Upon optimization, it was determined that the ideal reaction conditions involved solvent dimethyl sulfoxide at 110 °C for 3 h. The catalyst demonstrated excellent reactivity in the formation of various imines, intramolecularly cyclized amines, and substituted amines with a turnover number (TON) as high as 183. Depending on the base used for the reaction and the starting amines, the catalyst demonstrated high selectivity towards the product formation. The exploration into the mechanism and kinetics of the reaction pathway suggested the C-H activation as the rate-limiting step, with the reaction second-order overall, holding first-order behavior towards the catalyst and toluene substrate.
- Brandt, Andrew,Rangumagar, Ambar B.,Szwedo, Peter,Wayland, Hunter A.,Parnell, Charlette M.,Munshi, Pradip,Ghosh, Anindya
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p. 1862 - 1874
(2021/01/20)
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- Single crystal MnOOH nanotubes for selective oxidative coupling of anilines to aromatic azo compounds
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Catalytic synthesis of aromatic azo compounds by oxidative coupling of anilines using molecular oxygen represents a facile, green and valuable process; however, such an economical process suffers from poor catalytic activity and selectivity. Herein, novel single crystal MnOOH nanotubes with abundant Mn3+sites and high oxygen defects were successfully synthesized. The catalyst exhibited high selectivity for oxidative coupling of anilines, achieving complete transformation into aromatic azo compounds under mild conditions, even at room temperature.
- Cao, Fangxian,Li, Jiayuan,Qu, Yongquan,Zhang, Mingkai,Zhang, Sai,Zou, Yong
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supporting information
p. 19692 - 19697
(2021/09/20)
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- Gold-Catalyzed Bicyclic and [3+2]-Annulations of Internal Propargyl Alcohols with Nitrones and Imines To Yield to Two Distinct Heterocycles
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A gold-catalyzed synthesis of 1,3-dihydrooxazolo[3,4-a]indoles from 1-oxo-3-yn-4-ols and nitrones is described; this new bicyclic annulation presents the first examples that internal alkynes can react with nitrones to undergo an oxoarylation route. DFT calculations indicate a [3,3]-sigmatropic shift of initial alkenylgold intermediates to elude the intermediacy of gold carbenes. We also developed new [3+2]-annulations of the same 1-oxo-3-yn-4-ols with imines, yielding oxazolidin-4-ylidene derivatives efficiently. The tethered alcohols of these 1-oxo-3-ynes allow trapping of their metastable 2-azadienium intermediates to enable a novel annulation. Our mechanistic analysis indicates that the two products, despite their structural relevance, are produced from two independent systems. (Figure presented.).
- More, Sayaji Arjun,Chao, Tzu-Hsuan,Cheng, Mu-Jeng,Liu, Rai-Shung
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supporting information
p. 525 - 531
(2020/12/01)
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- Inverse Hydroboration of Imines with NHC-Boranes Is Promoted by Diphenyl Disulfide and Visible Light
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We describe a simple and efficient procedure for nucleophilic borylation of imines in the absence of a photoredox catalyst. Visible light irradiation of an acetonitrile solution of an imine, an NHC-borane, and diphenyl disulfide (10 mol %) provides various stable α-amino NHC-boranes in good yields. The reaction proceeds via addition of a nucleophilic boryl radical to an imine, followed by hydrogen abstraction from thiophenol, which is generated from NHC-borane and diphenyl disulfide.
- Kawamoto, Takuji,Morioka, Tsubasa,Noguchi, Kohki,Curran, Dennis P.,Kamimura, Akio
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supporting information
p. 1825 - 1828
(2021/03/08)
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- Synthesis of chromeno[3,4-b]piperazines by an enol-ugi/reduction/cyclization sequence
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Keto piperazines and aminocoumarins are privileged building blocks for the construction of geometrically constrained peptides and therefore valuable structures in drug discovery. Combining these two heterocycles provides unique rigid polycyclic peptidomimetics with drug-like properties including many points of diversity that could be modulated to interact with different biological receptors. This work describes an efficient multicomponent approach to condensed chromenopiperazines based on the novel enol-Ugi reaction. Importantly, this strategy involves the first reported post-condensation transformation of an enol-Ugi adduct.
- Bornadiego, Ana,Neo, Ana G.,Marcos, Carlos F.
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supporting information
(2021/05/31)
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- A novel water-dispersible and magnetically recyclable nickel nanoparticles for the one-pot reduction-Schiff base condensation of nitroarenes in pure water
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In this work, a heterogeneous nanocatalyst called Ni-Fe3O4@Pectin~PPA ~ Piconal was first synthesized, which was investigated as a bifunctional catalyst containing nickel functional groups. On the other hand, this Ni-Fe3O4@Pectin~PPA ~ Piconal catalyst in aqueous solvents shows a very effective performance at ambient temperature for the nitroarene reduction reaction with sodium borohydride, for which NaBH4 is considered as a reducing agent. This is a novelty magnetic catalyst that was approved by various methods, including Fourier-transform infrared spectroscopy (FT-IR), X-ray powder diffraction (XRD), Dynamic light scattering (DLS), Transmission electron microscopy (TEM), vibrating sample magnetometer (VSM), Inductively coupled plasma (ICP), Energy-dispersive X-ray spectroscopy (EDX), and Field emission scanning electron microscopy (FESEM) analyses. From the satisfactory results obtained from the reduction of nitrogen, this catalytic system is used for a one-pot protocol containing a reduction-Schiff base concentration of diverse nitroarenes. It was corroborated with the heterogeneous catalytic experiments on the one-pot tandem synthesis of imines from nitroarenes and aldehydes. Finally, the novel Ni-Fe3O4@Pectin~PPA ~ Piconal catalyst could function as a more economically desirable and environmentally amicable in the catalysis field. The favorable products are acquired in good to high performance in the attendance of Ni-Fe3O4@Pectin~PPA ~ Piconal as a bifunctional catalyst. This catalyst can be recycled up to six steps without losing a sharp drop.
- Ghamari Kargar, Pouya,Ravanjamjah, Asiye,Bagherzade, Ghodsieh
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p. 1916 - 1933
(2021/07/10)
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- Insight into the Modes of Activation of Pyridinium and Bipyridinium Salts in Non-Covalent Organocatalysis
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A series of pyridinium and bipyridinium salts were prepared and their catalytic properties were evaluated in the aza-Diels-Alder reaction between imines and Danishefsky diene. Depending on the substituents of the pyridinium/bipyridinium rings and on the nature of the counterion, two mechanisms of activation were demonstrated. In case of non-substituted rings, the substrate is activated through charge transfer involving the aryl ring on the C-side of the imine. When halogen atoms were introduced on the catalysts, the activation mode switched to halogen bond involving the imine nitrogen lone pair. Moreover, alternative activation modes based on hydrogen bonding and radical cation were ruled out. This work allowed us to develop two families of catalysts whose potential was demonstrated in the cycloaddition of various imines with Danishefsky diene. The first family is composed of the simple methyl pyridinium triflate and dioctyl bipyridinium triflate. The former is active only with imines bearing a p-methoxyphenyl group on the C-side and the latter was found to be efficient with imines bearing different substituents on both the N- and C-sides of the imines. The second family is based on halogenated pyridinium salts which proved active with almost all considered imines. (Figure presented.).
- Weiss, Robin,Golisano, Tamara,Pale, Patrick,Mamane, Victor
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supporting information
p. 4779 - 4788
(2021/09/06)
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- Cooperative catalysis of molybdenum with organocatalysts for distribution of products between amines and imines
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Multi-amino groups and nitrogen donors compound was discovered as an organocatalyst for N-alkylation of alcohols with amines in the presence of Mo(CO)6. The Mo(CO)6/organocatalyst binary system has shown to be a highly active catalyst for the N-alkylation reaction between alcohols and amines with excellent tolerance of variable starting materials bearing different functional groups. Of particular note, this method possessing a superiority selectivity in the synthesis of N-alkylated amines or imines, which can be controlled by the reaction temperature. The cooperative catalysis mechanism in combination of Mo(CO)6 with organocatalyst was elucidated by control experiments.
- Wu, Di,Bu, Qingqing,Guo, Cheng,Dai, Bin,Liu, Ning
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- Mn(III) active site in hydrotalcite efficiently catalyzes the oxidation of alkylarenes with molecular oxygen
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Developing efficient heterogeneous catalytic systems based on easily available materials and molecular oxygen for the selective oxidation of alkylarenes is highly desirable. In the present research, NiMn hydrotalcite (Ni2Mn-LDH) has been found as an efficient catalyst in the oxidation of alkylarenes using molecular oxygen as the sole oxidant without any additive. Impressive catalytic performance, excellent stability and recyclability, broad applicable scope and practical potential for the catalytic system have been observed. Mn3+ species was proposed to be the efficient active site, and Ni2+ played an important role in stabilizing the Mn3+ species in the hydrotalcite structure. The kinetic study showed that the aerobic oxidation of diphenylmethane is a first-order reaction over Ni2Mn-LDH with the activation energy (Ea) and pre-exponential factor (A0) being 85.7 kJ mol?1 and 1.8 × 109 min?1, respectively. The Gibbs free energy (ΔG≠) was determined to be -10.4 kJ mol-1 K-1 for the oxidation based on Eyring-Polanyi equation, indicating the reaction is exergonic. The mechanism study indicated that the reaction proceeded through both radical and carbocation intermediates. The two species were then trapped by molecular oxygen and H2O or hydroxyl species, respectively, to yield the corresponding products. The present research might provide information for constructing highly efficient and stable active site for the catalytic aerobic oxidation based on available and economic material.
- Wang, Anwei,Zhou, WeiYou,Sun, Zhonghua,Zhang, Zhong,Zhang, Zhihui,He, MingYang,Chen, Qun
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- Visible light-induced N-methyl activation of unsymmetric tertiary amines
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In the presence of methylene group, selective N-methyl activation of tertiary amines has been accomplished with the aid of visible light using organic photocatalyst under air. This protocol explores numerous aliphatic and aromatic substituted tetra-hydroquinoline analogues from various tertiary amines and maleimides. Furthermore, this approach was applied to activate the methyl group of N-methyl carbazole to generate the biologically active molecule.
- Perumal, Gopi,Kandasamy, Mohanraj,Ganesan, Balaji,Govindan, Karthick,Sathya, Harsha,Hung, Min-Yuan,Chandru Senadi, Gopal,Wu, Ya-Ching,Lin, Wei-Yu
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supporting information
(2021/01/09)
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- Redox-Neutral Imination of Alcohol with Azide: A Sustainable Alternative to the Staudinger/Aza-Wittig Reaction
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The traditional Staudinger/aza-Wittig reaction represents one of the most powerful tools for imine formation. However, for this multistep procedure, the sacrificial phosphine has to be used, resulting in difficulties in the purification process and waste disposal at the same time. Here, we report a redox-neutral azide-alcohol imination methodology enabled by a base-metal nickel PN3 pincer catalyst. The one-step, waste-free, and high atom-economical features highlight its advantages further. Moreover, mechanistic insight suggests a non-metal-ligand cooperation pathway based on the observation of an intermediate and density functional theory calculations.
- Li, Huaifeng,Lupp, Daniel,Das, Pradip K.,Yang, Li,Gon?alves, Théo P.,Huang, Mei-Hui,El Hajoui, Marwa,Liang, Lan-Chang,Huang, Kuo-Wei
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p. 4071 - 4076
(2021/04/12)
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- Iridium-Catalyzed Redox-Neutral C2 and C3 Dual C-H Functionalization of Indoles with Nitrones toward 7 H-Indolo[2,3- c]quinolines
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An iridium-catalyzed redox-neutral C-2 and C-3 dual C-H functionalization of indoles with nitrones has been developed, furnishing a range of 7H-indolo[2,3-c]quinolines with high efficiency and regioselectivity under mild reaction conditions. Notably, sequential multiple C-H bond cleavage and C-C bond formation constitute the key events of this process, in which nitrone serves as a building block and an oxidant. Distinct from the previous methods toward 7H-indolo[2,3-c]quinolines, this newly developed reaction features readily available substrates, operational simplicity, broad scope, good to high efficiency, and excellent regioselectivity.
- Li, Miao,Dong, Yaqun,Zhou, Cong,Bai, Junxue,Cheng, Jiang,Sun, Jianwei,Sun, Song
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supporting information
p. 8229 - 8234
(2021/10/25)
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- Regioselective Synthesis of 2° Amides Using Visible-Light-Induced Photoredox-Catalyzed Nonaqueous Oxidative C-N Cleavage of N, N-Dibenzylanilines
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A visible-light-driven photoredox-catalyzed nonaqueous oxidative C-N cleavage of N,N-dibenzylanilines to 2° amides is reported. Further, we have applied this protocol on 2-(dibenzylamino)benzamide to afford quinazolinones with (NH4)2S2O8 as an additive. Mechanistic studies imply that the reaction might undergo in situ generation of α-amino radical to imine by C-N bond cleavage followed by the addition of superoxide ion to form amides.
- Neerathilingam, Nalladhambi,Bhargava Reddy, Mandapati,Anandhan, Ramasamy
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supporting information
p. 15117 - 15127
(2021/10/25)
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