- Effect of the ancillary ligand in N-heterocyclic carbene iridium(III) catalyzed N-alkylation of amines with alcohols
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A series of air-stable N-heterocyclic carbene (NHC) Ir(III) complexes (Ir1-6), bearing various combinations of chlorine, pyridine and NHC ligands, were assayed for the N-alkylation of amines with alcohols. It was found that Ir3, with two monodentate 1,3-bis-methyl-imidazolylidene (IMe) ligands, emerged as the most active complex. A large variety of amines and primary alcohols were efficiently converted into mono-N-alkylated amines in 53–96% yields. As a special highlight, for the challenging MeOH, selective N-monomethylation could be achieved using KOH as a base under an air atmosphere. Moreover, this catalytic system was successfully applied to the gram-scale synthesis of some valuable compounds.
- Feng, Xinshu,Huang, Ming
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- Synthesis and characterization of N,N-chelate manganese complexes and applications in C[sbnd]N coupling reactions
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Bidentate NN-ligands have been derived from the reaction between aldehydes and 2-(aminomethyl)pyridine. The treatment of these ligands with Mn(CO)5Br gave complexes that are highly bench stable. The complexes were characterized by various analytical and spectral methods. Single-crystal XRD of complex Mn-2 was performed, which indicates an octahedral geometry around the metal center. The complexes efficiently catalyze the N-alkylation of anilines with alcohols under optimized reaction conditions.
- Das, Kuhali,Kumar, Amol,Jana, Akash,Maji, Biplab
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- Palladium supported on magnetic nanoparticles as recoverable catalyst for one-pot reductive amination of aldehydes with nitroarenes under ambient conditions
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A high-performance palladium-based catalyst has been prepared by the co-precipitation method. The catalyst was characterized by TEM, XRD, VSM and ICP. It was found that the catalyst showed a high activity for the one-pot direct reductive amination of aldehydes with nitroarenes in the presence of molecular hydrogen in ethanol, even at room temperature. Furthermore, the catalyst was easily recovered by applying an external magnet and reused for eight cycles without significant loss of activity.
- Wei, Shuoyun,Dong, Zhengping,Ma, Zongyan,Sun, Jian,Ma, Jiantai
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- Chromium-Catalyzed Alkylation of Amines by Alcohols
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The alkylation of amines by alcohols is a broadly applicable, sustainable, and selective method for the synthesis of alkyl amines, which are important bulk and fine chemicals, pharmaceuticals, and agrochemicals. We show that Cr complexes can catalyze this C?N bond formation reaction. We synthesized and isolated 35 examples of alkylated amines, including 13 previously undisclosed products, and the use of amino alcohols as alkylating agents was demonstrated. The catalyst tolerates numerous functional groups, including hydrogenation-sensitive examples. Compared to many other alcohol-based amine alkylation methods, where a stoichiometric amount of base is required, our Cr-based catalyst system gives yields higher than 90 % for various alkyl amines with a catalytic amount of base. Our study indicates that Cr complexes can catalyze borrowing hydrogen or hydrogen autotransfer reactions and could thus be an alternative to Fe, Co, and Mn, or noble metals in (de)hydrogenation catalysis.
- Fertig, Robin,Irrgang, Torsten,Kallmeier, Fabian,Kempe, Rhett
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- Palladium supported on hollow magnetic mesoporous spheres as recoverable catalyst for one-pot reductive amination of aldehydes with nitroarenes under mild conditions
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We described here a method to stabilize Pd(0) on the surface of hollow magnetic mesoporous spheres (HMMS), with Fe3O4 nanoparticles embedded in the mesoporous shell. The catalyst was characterized by TEM, XRD and VSM. It was found that the catalyst showed a high activity for the one-pot direct reductive amination of aldehydes with nitroarenes in the presence of molecular hydrogen in ethanol, even at room temperature. Besides, the catalyst could be recovered in a facile manner from the reaction mixture and recycled six times without loss in activity.
- Zhou, Jinghui,Dong, Zhengping,Wang, Peng,Shi, Zhiqiang,Zhou, Xingchun,Li, Rong
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- Effect of Ancillary Ligand in Cyclometalated Ru(II)-NHC-Catalyzed Transfer Hydrogenation of Unsaturated Compounds
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In an effort to develop efficient Ru(II)-NHC-based catalyst considering their stereoelectronic effect for hydride-transfer reaction, we found that the ancillary NHC ligand can play a significant role in its catalytic performance. This effect is demonstrated by comparing the activity of two different types of orthometalated precatalysts of general formula [(p-cymene)(NHC)RuII(X)] (NHC = an imidazolylidene-based ImNHC, compound 2a-c, or a mesoionic triazolylidene-based tzNHC, compound 4) in transfer hydrogenation of carbonyl substrates. The electron-rich precatalyst, 2c, containing p-OMe-substituted NHC ligand performed significantly better than both unsubstituted complex 2a and p-CF3 substituted electron-poor complex 2b in ketone reduction. Whereas bulky mesoionic triazolylidene ligand containing complex 4 was found to be superior catalyst for aldehyde reduction and the precatalyst 2a is more suitable for the selective transfer hydrogenation of a wide range of aromatic aldimines to amines. To the best of our knowledge, this is the first systematic study on the effect of stereoelectronic tuning of ancillary orthometalated NHC ligand in Ru(II)-catalyzed transfer hydrogenations of various types of unsaturated compounds with broad substrate scope.
- Bauri, Somnath,Donthireddy,Illam, Praseetha Mathoor,Rit, Arnab
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- Selective C-C bonds formation, N-alkylation and benzo[d]imidazoles synthesis by a recyclable zinc composite
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Earth abundant metals are much less expensive, promising, valuable metals and could be served as catalysts for the borrowing hydrogen reaction, dehydrogenation and heterocycles synthesis, instead of noble metals. The uniformly dispersed zinc composites were designed, synthesized and carefully characterized by means of XPS, EDS, TEM and XRD. The resulting zinc composite showed good catalytic activity for the N-alkylation of amines with amines, ketones with alcohols in water under base-free conditions, while unsaturated carbonyl compounds could also be synthesized by tuning the reaction conditions. Importantly, it was the first time to realize the synthesis of 2-aryl-1H-benzo[d]imidazole derivatives by using this zinc composite under green conditions. Meanwhile, this zinc catalyst could be easily recovered and reused for at least five times.
- Zhu, Guanxin,Duan, Zheng-Chao,Zhu, Haiyan,Ye, Dongdong,Wang, Dawei
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supporting information
p. 266 - 270
(2021/08/06)
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- Nickel Complexes Bearing N,N,O-Tridentate Salicylaldiminato Ligand: Efficient Catalysts for Imines Formation via Dehydrogenative Coupling of Primary Alcohols with Amines
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Treatment of salicylaldiminato ligand L1H-L2H (L1H = 2,4-di-tert-butyl-6-((quinolin-8-ylimino)methyl)phenol; L2H = 2,4-di-tert-butyl-6-(((2-(diethylamino)ethyl)imino)methyl)phenol) with Ni(OAc)2·4H2O in refluxing ethanol afforded nickel complexes [(L1)Ni(OAc)] (1) and [(L2)Ni(OAc)] (2), respectively. Reaction of L3H (L3H = (2,4-di-tert-butyl-6-(((2-(pyridin-2-yl)ethyl)imino)methyl)phenol)) with Ni(OAc)2·4H2O in the presence of excess triethylanmine gave the dual ligands coordinated nickel complex [(L2)2Ni] (3). Complexes 1-3 were well characterized by high-resolution mass spectrometry, infrared spectroscopy, elemental analysis, and X-ray diffraction analysis. All the three Ni(II) complexes exhibited efficient activity and good selectivity in the acceptorless dehydrogenative coupling of alcohols and amines to produce imines and diimines. The present protocol provides an atom-economical and sustainable route for the synthesis of various imine derivatives by employing an earth-abundant nickel salt and easily prepared salicylaldiminato ligands.
- Han, Zhangang,Hao, Zhiqiang,Lin, Jin,Lu, Guo-Liang,Zhang, Junhua,Zhang, Xiaoying
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p. 3843 - 3853
(2021/11/18)
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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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- The synthesis and structure of an amazing and stable carbonized material Cu-PC@OFM and its catalytic applications in water with mechanism explorations
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An amazing and stable carbonized octahedral frame material Cu-PC@OFM was synthesized and characterized through HRTEM, SEM, XRD, XPS, and Raman spectroscopy and nitrogen adsorption/desorption analysis. In particular, the carbon matrix carrier loaded with nano-copper not only maintains the original structure, but also the nano copper particles generatedin situsignificantly improve the catalytic performance and stability. It was disclosed that the copper-based catalyst material Cu-PC@OFM showed high catalytic activity in the borrowing hydrogen reaction and the synthesis of 1-benzyl-2-aryl-1H-benzo[d]imidazole derivatives with high yields in water. This copper catalytic system provided a much greener and efficient catalyst for the synthesis of functionalized amines and 1-benzyl-2-aryl-1H-benzo[d]imidazoles with good recovery performance in water, which was the first example for the Cu-PC@OFM material-catalyzed synthesis of 1-benzyl-2-aryl-1H-benzo[d]imidazoles. In addition, a plausible reaction mechanism was proposed through some condition control experiments, deuterium labeling experiments and separation of intermediates experiments.
- Tian, An-Qi,Luo, Xiang-Hao,Ren, Zhi-Lin,Zhao, Jun,Wang, Long
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supporting information
p. 9614 - 9620
(2021/06/12)
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- Ruthenium(ii) complexes with N-heterocyclic carbene-phosphine ligands for theN-alkylation of amines with alcohols
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Metal hydride complexes are key intermediates forN-alkylation of amines with alcohols by the borrowing hydrogen/hydrogen autotransfer (BH/HA) strategy. Reactivity tuning of metal hydride complexes could adjust the dehydrogenation of alcohols and the hydrogenation of imines. Herein we report ruthenium(ii) complexes with hetero-bidentate N-heterocyclic carbene (NHC)-phosphine ligands, which realize smart pathway selection in theN-alkylated reactionviareactivity tuning of [Ru-H] species by hetero-bidentate ligands. In particular, complex6cbwith a phenyl wingtip group and BArF?counter anion, is shown to be one of the most efficient pre-catalysts for this transformation (temperature is as low as 70 °C, neat conditions and catalyst loading is as low as 0.25 mol%). A large variety of (hetero)aromatic amines and primary alcohols were efficiently converted into mono-N-alkylated amines in good to excellent isolated yields. Notably, aliphatic amines, challenging methanol and diamines could also be transformed into the desired products. Detailed control experiments and density functional theory (DFT) calculations provide insights to understand the mechanism and the smart pathway selectionvia[Ru-H] species in this process.
- Huang, Ming,Li, Yinwu,Lan, Xiao-Bing,Liu, Jiahao,Zhao, Cunyuan,Liu, Yan,Ke, Zhuofeng
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supporting information
p. 3451 - 3461
(2021/05/03)
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- Enhanced Hydride Donation Achieved Molybdenum Catalyzed Direct N-Alkylation of Anilines or Nitroarenes with Alcohols: From Computational Design to Experiment
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An example of homogeneous Mo-catalyzed direct N-alkylation of anilines or nitroarenes with alcohols is presented. The DFT aimed design suggested the easily accessible bis-NHC-Mo(0) complex features a strong hydride-donating ability, achieving effective N-alkylation of anilines or challenging nitroarenes with alcohols. The enhanced hydride-donating strategy should be useful in designing highly active systems for borrowing hydrogen transformations.
- Huang, Ming,Huang, Yong-Liang,Ke, Zhuofeng,Lan, Xiao-Bing,Li, Weikang,Liu, Jiahao,Liu, Yan,Ye, Zongren,Zhao, Cunyuan
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p. 10377 - 10382
(2021/08/31)
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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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- 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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- Catalyst- And solvent-free efficient access to: N -alkylated amines via reductive amination using HBpin
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A sustainable approach which works under catalyst- and solvent-free conditions for the synthesis of structurally diverse secondary amines has been uncovered. This one-pot protocol works efficiently at room temperature and is compatible with a wide range of sterically and electronically diverse aldehydes and primary amines. Notably, this simple process offers scalability, excellent functional group tolerance, chemoselectivity, and is also effective at the synthesis of biologically relevant molecules. This journal is
- Bauri, Somnath,Pandey, Vipin K.,Rit, Arnab
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p. 3853 - 3857
(2020/07/27)
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- Method for efficiently realizing N-alkylation reaction by using cyclic iridium catalyst
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The invention discloses a method for efficiently realizing N-alkylation reaction by using a cyclic iridium catalyst, and belongs to the technical field of pharmaceutical and chemical synthesis. The preparation method comprises the following steps of: taking amines and alcohol compounds as raw materials, a cyclic iridium complex as a catalyst and water or an organic solvent as a reaction medium, heating, stirring and reacting for 12-24 hours under the protection of inert gas, cooling to room temperature after the reaction is finished, carrying out reduced pressure distillation and concentrationto obtain a crude product, and carrying out column chromatography purification to obtain a series of amine compounds. The synthesis method of the amine compound is simple to operate, easily availablein raw materials and low in price; the method is high in reaction efficiency, good in N-alkylation selectivity, good in adaptability to various functional groups, wide in substrate universality and environmentally friendly, is carried out at the gram level, shows the potential of industrially synthesizing the N-alkylamine compound, and has wide application prospects in the fields of medicines, organic synthesis and the like.
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Paragraph 0080-0086
(2020/11/10)
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- Pyridine mediated transition-metal-free direct alkylation of anilines using alcohols: via borrowing hydrogen conditions
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Herein, we report pyridine and other similar azaaromatics as efficient biomimetic hydrogen shuttles for a transition-metal-free direct N-alkylation of aryl and heteroaryl amines using a variety of benzylic and straight chain alcohols. Mechanistic studies including deuterium labeling and the isolation of dihydro-intermediates of the benzannulated pyridine confirmed the role of pyridine and a borrowing hydrogen process operating in these reactions. In addition, we have extended this methodology for the development of dehydrogenative synthesis of quinolines and indoles, as well as the transfer hydrogenation of ketones. This journal is
- Pothikumar, Rajagopal,Bhat, Venugopal T,Namitharan, Kayambu
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supporting information
p. 13607 - 13610
(2020/11/17)
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- Ruthenium(II) Complexes of Heteroditopic N-Heterocyclic Carbene Ligands: Efficient Catalysts for C-N Bond Formation via a Hydrogen-Borrowing Strategy under Solvent-Free Conditions
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Both imidazol-2-ylidene (ImNHC) and 1,2,3-triazol-5-ylidene (tzNHC) have evolved to be elite groups of N-heterocyclic carbene (NHC) ligands for homogeneous catalysis. To develop efficient ruthenium(II)-based catalysts incorporating these ligands for C-N bond-forming reactions via hydrogen-borrowing methodology, we utilized chelating ligands integrated with ImNHC and mesoionic tzNHC donors connected via a CH2 spacer with a diverse triazole backbone. The synthesized ruthenium(II) complexes 3 are found to be highly efficient for C-N bond formation across a wide range of primary amine and alcohol substrates under solvent-free conditions, and among all of the complexes studied here, catalyst 3a with a mesityl substituent displayed maximum activity. To our delight, catalyst 3a is also effective for the selective mono-N-methylation of various anilines utilizing methanol as a coupling partner, known to be relatively more difficult than other alcohols. Furthermore, complex 3a also delivers various substituted quinolines successfully via the reaction of 2-aminobenzyl alcohol with several secondary alcohols. Importantly, catalyst 3a exhibited the highest activity among the reported ruthenium(II) complexes for both the N-benzylation of aniline [achieving a turnover number (TON) of 50000] and the realization of quinoline 8a by reacting 2-aminobenzyl alcohol with 2-phenylethanol (attaining a TON of 30000).
- Donthireddy,Mathoor Illam, Praseetha,Rit, Arnab
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supporting information
p. 1835 - 1847
(2020/01/31)
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- Catalytic Selective Oxidative Coupling of Secondary N-Alkylanilines: An Approach to Azoxyarene
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Azoxyarenes are among important scaffolds in organic molecules. Direct oxidative coupling of primary anilines provides a concise fashion to construct them. However, whether these scaffolds can be prepared from secondary N-alkylanilines is not well explored. Here, we present a catalytic selective oxidative coupling of secondary N-alkylaniline to afford azoxyarene with tungsten catalyst under mild conditions. In addition, azoxy can be viewed as a bioisostere of alkene and amide. Several "azoxyarene analogues" of the corresponding bioactive alkenes and amides showed comparable promising anticancer activities.
- Ke, Lei,Zhu, Guirong,Qian, Hui,Xiang, Guangya,Chen, Qin,Chen, Zhilong
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supporting information
p. 4008 - 4013
(2019/06/04)
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- Catalyst-Free Reductive Coupling of Aromatic and Aliphatic Nitro Compounds with Organohalides
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A rare reductive coupling of nitro compounds with organohalides has been realized. The reaction is initiated by a partial reduction of the nitro group to a nitrenoid intermediate. Therefore, not only aromatic but also aliphatic nitro compounds are efficiently transformed into monoalkylated amines, with organohalides as the alkylating agent. Given the innate reactivity of the nitrenoid, a catalyst is not required, resulting in a high tolerance for aryl halide substituents in both starting materials.
- Rauser, Marian,Eckert, Raphael,Gerbershagen, Max,Niggemann, Meike
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supporting information
p. 6713 - 6717
(2019/04/14)
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- Catalyst-Free and Solvent-Free Facile Hydroboration of Imines
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A facile process for the catalyst-free and solvent-free hydroboration of aromatic as well as heteroaromatic imines is reported. This atom-economic methodology is scalable, compatible with sterically and electronically diverse imines, displaying excellent tolerance towards various functional groups, and works efficiently at ambient temperature in most of the cases, affording secondary amines in good to excellent yield after hydrolysis.
- Pandey, Vipin K.,Donthireddy, Siva Nagendra Reddy,Rit, Arnab
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supporting information
p. 3255 - 3258
(2019/09/17)
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- Alcohol Amination Catalyzed by Copper Powder as a Self-Supported Catalyst
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Catalytic alcohol amination is a sustainable reaction for N-alkyl amine synthesis. Homogeneous and supported copper catalysts have long been studied for this reaction and have given some impressive results. In this study, copper powder is found to behave as an active catalyst for alcohol amination, giving better catalytic performance than metal-oxide-supported nanocopper catalysts. Catalyst characterization suggests that the copper powder can be considered as a self-supported nanocopper catalyst (i.e., nanocopper supported on copper particles). These results might promote the study of unsupported transition metal powders in sustainable catalytic reactions.
- Wu, Yajuan,Huang, Yongji,Dai, Xingchao,Shi, Feng
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p. 3185 - 3191
(2018/11/30)
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- Unsymmetrical triazolyl-naphthyridinyl-pyridine bridged highly active copper complexes supported on reduced graphene oxide and their application in water
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A novel unsymmetrical triazolyl-naphthyridinyl-pyridine ligand was designed and synthesized, and employed in the synthesis of a heterogeneous copper complex on reduced graphene oxide. The resulting copper composite was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and energy dispersive X-ray spectroscopy (EDX). This supported copper catalyst containing unsymmetrical triazolyl-naphthyridinyl-pyridine (only 0.1 mol%) showed excellent catalytic activity in water with good recyclability. Various functionalized quinoline derivatives were successfully synthesized in high yields through the green strategy in water. Other heterocyclic compounds, such as pyridine, 2-(pyridin-2-yl)quinoline, 1,8-naphthyridine, 5,6-dihydronaphtho[1,2-b][1,8]naphthyridine and 2-(pyridin-2-yl)-1,8-naphthyridine derivatives, were achieved in water with more than 80% yields. Mechanism studies revealed that this transformation occurs via dehydrogenation, condensation, and transfer hydrogenation and dehydrogenation processes which was supported by a deuterium labeling experiment.
- Hu, Wenkang,Zhang, Yilin,Zhu, Haiyan,Ye, Dongdong,Wang, Dawei
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supporting information
p. 5345 - 5351
(2019/10/11)
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- Room temperature N-heterocyclic carbene manganese catalyzed selective N-alkylation of anilines with alcohols
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The first example of room temperature non-noble metal homogeneous system catalyzed selective N-alkylation of anilines with alcohols by a bis-NHC manganese complex is presented. This system was applied to a large range of alcohols and anilines, including biologically relevant motifs and challenging methanol. Experimental and computational studies suggest an outer-sphere mechanism for this NHC-Mn system.
- Huang, Ming,Li, Yukui,Li, Yinwu,Liu, Jiahao,Shu, Siwei,Liu, Yan,Ke, Zhuofeng
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supporting information
p. 6213 - 6216
(2019/06/07)
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- Sublimation-Induced Sulfur Vacancies in MoS2 Catalyst for One-Pot Synthesis of Secondary Amines
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MoS2 catalysts with abundant S and Mo defects have been developed for the one-pot reductive amination of nitro compounds with aldehydes to synthesize secondary amines. The combination of multiple structural characterizations demonstrates that the density of S vacancies can be tuned by changing the thermal sublimation temperature. The experimental results and DFT calculations demonstrate that S vacancies on the surface of MoS2 are the active sites for the hydrogenation of the intermediate imines to the final products secondary amines.
- Zhang, Yunrui,Gao, Yongjun,Yao, Siyu,Li, Siwei,Asakura, Hiroyuki,Teramura, Kentaro,Wang, Haijun,Ma, Ding
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p. 7967 - 7975
(2019/08/21)
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- Mild and efficient synthesis of secondary aromatic amines by one-pot stepwise reductive amination of arylaldehydes with nitroarenes promoted by reusable nickel nanoparticles
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The one-pot stepwise reductive amination of arylaldehydes with nitroarenes is described, using reusable nickel nanoparticles (Ni-pol) as catalyst and NaBH4 as mild, inexpensive, and safe reducing agent. The proposed catalytic system holds several advantages such as the use of a non-precious and earth-abundant metal, the facile separation of the catalyst from the reaction mixture by centrifugation, excellent stability towards air and moisture, very mild reaction conditions, good recyclability, broad substrate scope with good to excellent yields, and easy scalability (up to 1.0 g). FESEM analyses indicate that the active species are cubic nanocrystals of Ni in the average cross section value of 35 nm with a quite narrow (25–45 nm) and monomodal distribution, which becomes bimodal with the recycling reactions but without agglomeration.
- Fiore, Ambra Maria,Romanazzi, Giuseppe,Dell'Anna, Maria Michela,Latronico, Mario,Leonelli, Cristina,Mali, Matilda,Rizzuti, Antonino,Mastrorilli, Piero
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- Heteroditopic Ru(II)-And Ir(III)-NHC Complexes with Pendant 1,2,3-Triazole/Triazolylidene Groups: Stereoelectronic Impact on Transfer Hydrogenation of Unsaturated Compounds
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Imidazol-2-ylidene (ImNHC) and 1,2,3-Traizol-5-ylidene (tzNHC) have been established as important classes of carbene ligands in homogeneous catalysis. To develop Ru(II)/Ir(III) complexes based on these ligand systems considering their electronic as well as steric profiles for hydride transfer reactions, we employed chelating ligands featuring combinations of ImNHC and triazole-N or mesoionic tzNHC donors bridged by a CH2 spacer with possible modifications at triazole backbone. In general, synthesized Ru(II) complexes were found to perform significantly better than analogous Ir(III) complexes in ketone and aldimine reduction. Among the Ru(II) complexes, electron-rich complexes 8/9 of the general formula [(p-cymene)(ImNHC-CH2-TzNHC)RuII(Cl)]BF4 with two different carbene donors (ImNHC and tzNHC) were found to perform appreciably better in ketone reduction than analogous complexes with a combination of ImNHC and triazole-N-donor ([(p-cymene)(ImNHC-CH2-Tz-N)RuII(Cl)]BF4; 4) explaining the electronic fine-Tuning of the catalytic systems. No appreciable variation in activity was observed between complexes 8 and 9 having almost similar electronic profiles. However, less bulky Ru(II) complex 9 with a triazole N-phenyl substituent is more suitable for aldimine reduction than is complex 8, having a triazole N-3,5-dimethylphenyl substituent that explains the steric influence in addition to electronic effect on the reduction process.
- Illam, Praseetha Mathoor,Donthireddy,Chakrabartty, Sayantan,Rit, Arnab
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supporting information
p. 2610 - 2623
(2019/07/31)
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- Direct Reductive Amination of Carbonyl Compounds Catalyzed by a Moisture Tolerant Tin(IV) Lewis Acid
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Despite the ever-broadening applications of main-group ‘frustrated Lewis pair’ (FLP) chemistry to both new and established reactions, their typical intolerance of water, especially at elevated temperatures (>100 °C), represents a key barrier to their mainstream adoption. Herein we report that FLPs based on the Lewis acid iPr3SnOTf are moisture tolerant in the presence of moderately strong nitrogenous bases, even under high temperature regimes, allowing them to operate as simple and effective catalysts for the reductive amination of organic carbonyls, including for challenging bulky amine and carbonyl substrate partners. (Figure presented.).
- Sapsford, Joshua S.,Scott, Daniel J.,Allcock, Nathan J.,Fuchter, Matthew J.,Tighe, Christopher J.,Ashley, Andrew E.
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supporting information
p. 1066 - 1071
(2018/01/27)
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- BINAP-copper supported by hydrotalcite as an efficient catalyst for the borrowing hydrogen reaction and dehydrogenation cyclization under water or solvent-free conditions
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A BINAP-Cu system supported by hydrotalcite has been developed and proved to be a highly efficient catalyst for the atom-efficient and green borrowing hydrogen reaction and dehydrogenative cyclization. This BINAP-Cu complex supported by hydrotalcite is highly air-stable and can be recycled at least five times under solvent-free conditions. Notably, 1-benzyl-2-aryl-1H-benzo[d]imidazole derivatives could be synthesized from alcohols in only one step with water as the solvent for the first time. This provided a much greener and efficient catalytic method towards the synthesis of functionalized amines, ketones and 1-benzyl-2-aryl-1H-benzo[d]imidazole derivatives with high yields under water or solvent-free conditions.
- Xu, Zhaojun,Yu, Xiaoli,Sang, Xinxin,Wang, Dawei
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supporting information
p. 2571 - 2577
(2018/06/11)
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- AuPd?Fe3O4 Nanoparticle Catalysts for Highly Selective, One-Pot Cascade Nitro-Reduction and Reductive Amination
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Exceedingly chemoselective preparation of secondary amines from the cascade reaction of nitro reduction followed by reductive amination of the resulting amine with an aldehyde through the use of bimetallic AuPd alloy nanoparticle catalyst is described. We prepared a AuPd alloy nanocatalyst supported on Fe3O4 in gram scale without calcination. One pot synthesis of a number of secondary amines was achieved from a variety of nitroarenes and aryl or alkyl aldehydes under 1 atm of H2 at room temperature. No N-debenzylation was observed in the case of the reactions involving aryl aldehydes, which is often observed in the reductive amination catalysed by a transition metal catalyst such as palladium. We also accomplished efficient one-pot synthesis of a number of N-aryl substituted isoindolinone derivatives from 1-formylbenzoic acid and several nitroarenes using the same reaction conditions. Furthermore, thanks to the magnetic property of the Fe3O4 support, the AuPd?Fe3O4 NPs could be easily separated and reused up to 20 times without the loss of its catalytic activity. (Figure presented.).
- Cho, Ahra,Byun, Sangmoon,Kim, B. Moon
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supporting information
p. 1253 - 1261
(2018/02/21)
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- An Efficient Homogenized Ruthenium(II) Pincer Complex for N-Monoalkylation of Amines with Alcohols
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An ionic 2,6-bis(imidazo[1,2-α]pyridin-2-yl)pyridine-based N^N^N pincer ruthenium(II) complex exhibited high efficiency in the C–N bond formation between amines and alcohols by the “borrowing hydrogen” (BH) or “hydrogen autotransfer” (HA) concept. The synthetic protocol selectively generated monoalkylated amines without formation of tertiary amines during the reaction. The unique selectivity enabled the formation of symmetrically and asymmetrically substituted diamines. This methodology features several advantages including a low catalyst loading (as low as 0.5 mol-%), a short reaction time (as short as 2 h), and excellent N-monoalkylation selectivity.
- Yang, Fa-Liu,Wang, Ying-Hui,Ni, Yong-Feng,Gao, Xiang,Song, Bing,Zhu, Xinju,Hao, Xin-Qi
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p. 3481 - 3486
(2017/07/04)
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- Tunable Triazole-Phosphine-Copper Catalysts for the Synthesis of 2-Aryl-1H-benzo[d]imidazoles from Benzyl Alcohols and Diamines by Acceptorless Dehydrogenation and Borrowing Hydrogen Reactions
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Triazole-phosphine-copper complexes (TAP?Cu) have been synthesized and applied as tunable and efficient catalysts for the selective synthesis of fluoro-substituted 2-aryl-1H-benzo[d]imidazole and 1-benzyl-2-aryl-1H-benzo[d]imidazole derivatives from simple alcohols in only one step. TAP?Cu exhibited excellent and tunable catalytic activity for both dehydrogenation and borrowing hydrogen reactions with more than 80 examples being demonstrated for the first time. It was observed that the ligand played a critical role in catalyst activity. Mechanistic studies and deuterium labeling experiments indicated that the reactions proceeded by an initial and reversible alcohol dehydrogenation resulting in a copper hydride intermediate. This was also supported by the direct observation of a diagnostic copper hydride signal by solid-state infrared spectroscopy. The TAP?Cu-H complex showed absorptions at 912 cm?1 that could be assigned to copper?hydride stretches. Furthermore, the direct trapping of an intermediate bisimine was also successfully performed. (Figure presented.).
- Xu, Zhaojun,Wang, Duo-Sheng,Yu, Xiaoli,Yang, Yongchun,Wang, Dawei
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supporting information
p. 3332 - 3340
(2017/10/06)
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- Efficient and practical catalyst-free-like dehydrative N-alkylation of amines and sulfinamides with alcohols initiated by aerobic oxidation of alcohols under air
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We developed simple and practical N-alkylation reactions of amines and sulfinamides with primary and secondary alcohols by using only catalytic amounts of air as the initiator without adding any external catalysts. This method has advantages of simple conditions, easy operation, and comparatively wider scope of substrates, providing an efficient and green catalyst-free-like alcohol-based dehydrative N-alkylation method. Mechanistic studies revealed that air initiated the reactions by aerobic oxidation of the alcohols to the key initiating aldehydes or ketones in the presence of bases.
- Li, Xiaohui,Li, Shuangyan,Li, Qiang,Dong, Xu,Li, Yang,Yu, Xiaochun,Xu, Qing
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supporting information
p. 264 - 272
(2015/12/30)
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- A conjugated ketone as a catalyst in alcohol amination reactions under transition-metal and hetero-atom free conditions
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Here, we show the results of a molecular-defined conjugated ketone catalyzed alcohol amination reaction. Under the optimized reaction conditions, the yields to the desired products reached 98%. The reaction mechanism and kinetic study supposed that carbonyl-hydroxyl groups are the catalytically active sites, and the transfer-hydrogenation reactions progress via the recycling of carbonyl and hydroxyl groups. The catalytic process shows promise as an efficient and economic route for alcohol amination reactions.
- Dai, Xingchao,Cui, Xinjiang,Deng, Youquan,Shi, Feng
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p. 43589 - 43593
(2015/05/27)
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- A ruthenium-based catalytic system for a mild borrowing-hydrogen process
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The alkylation of arylamines using stoichiometric amounts of aliphatic and benzylic alcohols in the presence of tBuOK was carried out at 55 °C using a low catalyst loading of [Ru(cod)-Cl2]n/PTA (1,3,5-triaza-7-phosphaadamantane). The overall borrowing-hydrogen process does not require a controlled nitrogen atmosphere, and it could also be carried out at room temperature using higher loading of base. A wide range of substrates can be used in this transformation, and it has a good tolerance of different substituents. This catalytic system proved also to be efficient for other hydrogen-transfer reactions such as a tandem oxidation/C-C coupling between 1-phenylethanol and primary alcohols.
- Jumde, Varsha R.,Gonsalvi, Luca,Guerriero, Antonella,Peruzzini, Maurizio,Taddei, Maurizio
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p. 1829 - 1833
(2015/05/27)
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- Programmed synthesis palladium supported on Fe3O4@C: An efficient and heterogeneous recyclable catalyst for one-pot reductive amination of aldehydes with nitroarenes in aqueous reaction medium
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A highly efficient Pd/Fe3O4@C catalytic system has been developed for direct reductive amination of carbonyl compounds with nitroarenes in aqueous reaction medium. The catalyst was characterized by TEM, XRD, XPS and VSM. It was found that the catalyst showed a high activity for the one-pot direct reductive amination of aldehydes with nitroarenes in the presence of molecular hydrogen at mild temperature. Besides, the catalyst could be recovered in a facile manner from the reaction mixture and recycled six times without obvious loss in activity.
- Zhou, Xingchun,Li, Xinzhe,Jiao, Lixin,Huo, Hongfei,Li, Rong
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p. 1591 - 1599
(2017/05/22)
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- Reductive amination of aldehydes and amines with an efficient Pd/NiO catalyst
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By applying a simple Pd/NiO catalyst, the reductive amination of amines and aldehydes can progress efficiently under mild reaction conditions, and 24 substituted amines with different structures were synthesized with up to 98% isolated yields.
- Yang, Huimin,Cui, Xinjiang,Deng, Youquan,Shi, Feng
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supporting information
p. 1314 - 1322
(2014/04/17)
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- Synthesis of imidazolidin-2-ones employing dialkyl carbonates as an ecofriendly carbonylation source
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A new approach to the synthesis of imidazolidin-2-ones by carbonylation of vicinal diamines with dialkyl carbonates using Pb(NO3)2 and Cu(ii) salts as catalysts has been described in the present protocol. A comparative study using Cu(ii) salts and Pb(NO3)2 as catalysts has suggested Cu(NO3)2 and CuCl 2·2H2O salts to be as promising as Pb(NO 3)2 and can replace the latter in the carbonylation reactions employing dialkyl carbonates. the Partner Organisations 2014.
- Badru, Rahul,Singh, Baldev
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p. 38978 - 38985
(2014/11/07)
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- Base-mediated synthesis of imines and amines from N-phenylureas and alcohols
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A new base-mediated protocol has been developed for the synthesis of imines and amines from N-phenylureas and alcohols under normal air. From the synthetic point of view, the protocol can be considered as an efficient alternative to conventional methods for the synthesis of imines and amines in moderate to excellent yields.Georg Thieme Verlag Stuttgart. New York.
- Yadav, Dilip Kumar T.,Bhanage, Bhalchandra M.
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supporting information
p. 1611 - 1615
(2014/07/08)
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- N-Alkylation of amines through hydrogen borrowing over a heterogeneous Cu catalyst
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Substitution of alkylhalides for the synthesis of amines is a relevant target for synthetic chemists. Secondary amines can be obtained in a one pot-one step reaction from secondary and benzylic alcohols and aniline over a heterogeneous copper catalyst. The process does not require any additive, is intrinsically safe and produces no waste.
- Santoro, Federica,Psaro, Rinaldo,Ravasio, Nicoletta,Zaccheria, Federica
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p. 2596 - 2600
(2014/01/06)
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- N-Alkylation of amines with alcohols over nanosized zeolite beta
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Direct N-alkylation of amines with alcohols was successfully performed by using nanosized zeolite beta, which showed the highest catalytic activity among other conventional zeolites. This method has several advantages, such as eco-friendliness, moderate to high yields, and simple work-up procedure. The catalyst was successfully recovered and reused without significant loss of activity and only water is produced as co-product. In addition, imines were also efficiently prepared from the tandem reactions of amines with 2-, 3- and 4-nitrobenzyl alcohols using nanosized zeolite beta.
- Reddy, Marri Mahender,Kumar, Macharla Arun,Swamy, Peraka,Naresh, Mameda,Srujana, Kodumuri,Satyanarayana, Lanka,Venugopal, Akula,Narender, Nama
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supporting information
p. 3474 - 3483
(2013/12/04)
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- Iron triflate catalyzed reductive amination of aldehydes using sodium borohydride
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An efficient and convenient procedure for the reductive amination of aldehydes using NaBH4 in the presence of catalytic amount of Fe(OTf)3 is described.
- Uday Kumar,Sudhakar Reddy,Prabhakar Reddy,Bandichhor, Rakeshwar
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supporting information; experimental part
p. 4354 - 4356
(2012/10/08)
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- Catalyst-free one-pot reductive alkylation of primary and secondary amines and N,N-dimethylation of amino acids using sodium borohydride in 2,2,2-trifluoroethanol
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A simple and convenient procedure for the reductive alkylation of primary and secondary amines and N,N-dimethylation of amino acids is described using sodium borohydride as a reducing agent in 2,2,2- trifluoroethanol without use of a catalyst or any other additive. The solvent can be readily recovered from reaction products in excellent purity for direct reuse. Georg Thieme Verlag Stuttgart - New York.
- Tajbakhsh, Mahmood,Hosseinzadeh, Rahman,Alinezhad, Heshmatollah,Ghahari, Somayeh,Heydari, Akbar,Khaksar, Samad
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experimental part
p. 490 - 496
(2011/03/20)
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- Practical one-pot synthesis of secondary amines by zinc-catalyzed reductive amination
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In the present study, the zinc-catalyzed reductive amination of various aldehydes has been examined in detail. Simple zinc(II) triflate was applied as hydrosilylation catalyst for the reduction of the in situ formed imine by condensation of an aldehyde with an amine. Using a practical Lewis acid catalyst and PMHS [poly(methylhydrosiloxane)] as cheap hydride source excellent yields and a broad functional group tolerance were achieved.
- Enthaler, Stephan
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experimental part
p. 55 - 61
(2011/10/05)
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- Thiourea-catalyzed transfer hydrogenation of aldimines
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The present letter reports on the thiourea-catalyzed transfer hydrogenation of imines through hydrogen-bonding activation with Hantzsch 1,4-dihydropyridine as the hydrogen source. A variety of aromatic as well as aliphatic aldimines can be reduced to give
- Zhang, Zhiguo,Schreiner, Peter R.
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p. 1455 - 1457
(2008/03/11)
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- Condensed 1,8-Naphthyridines: Part VIII - Synthesis of 2-Arylpyrimidonaphthyridin-4(3H)-ones
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2-Arylpyrimidonaphthyridin-4(3H)-ones (III) have been synthesized (i) by oxidation of 2,3-dihydro-2-arylpyrimidonaphthyridin-4(1H)-ones (II) with nitrobenzene-acetic acid, which in turn have been obtained by the condensation of 2-amino-1,8-naphthyridine-3-carboxamide (I) with aromatic aldehydes in gl. acetic acid, and (ii) by the condensation of 2-amino-1,8-naphthyridine-3-carboxamide (I) with either aromatic aldehydes in nitrobenzene-acetic acid or schiff bases in gl. acetic acid.The structural assignments of all the products are based on elemental analyses and spectral (IR, mass and PMR) data.
- Rajendar Reddy, K.,Mogilaiah, K.,Sreenivasulu, B.
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p. 1194 - 1196
(2007/10/02)
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- EFFECTS OF SUBSTITUENTS IN THE BENZYL BROMIDE ON THE KINETICS OF THE BENZYLATION OF AMINES
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The kinetics of the reactions of 3- and 4-substituted benzyl bromides with amines having various structures in nitrobenzene at 40 deg C were investigated.The 4-substituted benzyl bromides have higher reactivity compared with that calculated on the basis of the linear correlations according to the Hammett-Taft equation for unsubstituted and 3-substituted benzyl bromides containing electron-withdrawning substituents.The reactivity of benzyl bromides containing electron-donating substituents obeys a linear correlation with the ?+ constants.The effects of structural changes in the substrate and the nucleophile on the character of the transition states of the investigated reactions is discussed.
- Shpan'ko, I. V.,Korostylev, A. P.,Rusu, L. N.
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p. 1715 - 1723
(2007/10/02)
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- MUTUAL EFFECTS OF STRUCTURE IN THE REACTIONS OF BENZYL BROMIDES WITH PRIMARY ARYLAMINES IN A MIXTURE OF NITROBENZENE AND DIMETHYLSULFOXIDE
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The kinetics of the reaction of benzyl bromides with primary arylamines in a 1 M solution of dimethyl sulfoxide in benzene were studied.The joint effect of the substituents on the reactivity of the benzyl bromide-primary arylamine system was evaluated qua
- Litvinenko, L. M.,Shpan'ko, I. V.,Korostylev, A. P.
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p. 854 - 859
(2007/10/02)
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- Method of topically treating inflammation
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This invention describes a method of treating inflammation in warmblooded animals by topically administering an effective amount of benzylamine and its derivatives.
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