- Synthesis and characterization of bidentate NHC-Pd complexes and their role in amination reactions
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The new well-defined and air-stable ortho-xylyl-linked N-heterocyclic carbene (NHC) Pd complexes (2a-d) have been synthesized and characterized by elemental analysis, 1H NMR, 13C NMR, IR spectroscopy, and single crystal X-ray diffraction studies. The palladium atom in the complex 2a lies on a crystallographic mirror plane and can be described as having a square-planar coordination environment with the carbene atoms of the benzimidazole rings of the ligand occupying two coordination sites in cis positions. Two further coordination sites are occupied by chloride ligands. The benzimidazole rings are connected to each other by an ortho-xylyl bridge. The catalytic activity of these palladium complexes has been tested in the coupling reactions of various N-containing substrates with bromobenzene. A preliminary catalytic study shows that the bis(NHC)-Pd complexes are highly active in the Buchwald-Hartwig amination reaction.
- Demir, Serpil,?zdemir, Ismail,?etinkaya, Bekir,Arslan, Hakan,VanDerveer, Don
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- Reduction of imines to amines through use of Cp2MoH2 and protonic acid system
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Imines are conveniently reduced to the corresponding amines by molybdenum dihydride CpMoH2 under mild conditions in good yields.In the presence of a ketone only an imine was reduced and the ketone was recovered quantitatively.
- Minato, Makoto,Fujiwara, Yutaka,Ito, Takashi
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- THE ACTUAL MERCURATING SPECIES IN THE MERCURATION OF AROMATIC AMINES AND THE AMINOMERCURATION OF OLEFINS
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The reactivity of ?- and ?- N-mercurated and C-mercurated amines as electrophiles towards olefins and aromatic amines is studied under different reaction conditions.Depending on the ionic or covalent character of the starting mercury(II) salt, dissociated
- Barluenga, Jose,Bayon, Ana M.,Perez-Prieto, Julia,Asensio, Gregorio
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- Highly Coordinated Tin Hydrides: A Novel Synthesis of Tertiary Amines via Hydrostannation of Imines
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The highly coordinated tin hydride, Bu2SnClH-HMPA (B), is shown to be an effective agent for the reduction of imines.The subsequent alkylation of the resulting intermediate tin amides permitted the preparation of a series of tertiary amines in a one-pot procedure.The spectral identification of the novel tin hydrides, B and Bu2SnClH-Bu4NF, was accomplished by 1H, 13C, and 119Sn NMR and FT-IR studies.
- Kawakami, Takayo,Sugimoto, Takayuki,Shibata, Ikuya,Baba, Akio,Matsuda, Haruo,Sonoda, Noboru
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- ELECTROLYTIC BEHAVIOR OF TETRASUBSTITUTED IMINIUM SALT IN ACETONITRILE.
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Cathodic behavior of N-cyclohexylidenepyrrolidinium salt (1) and N-cyclohexylideneaniline (2) in acetonitrile has been studied by means of dc polarography, cyclic voltammetry and preparative electrolysis under controlled potential conditions. Compound 1 e
- Kunai,Harada,Nishihara,Yanagi,Sasaki
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- Synthesis of palladium complexes derived from imidazolidin-2-ylidene ligands and used for catalytic amination reactions
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N-Aryl amination and the Buchwald–Hartwig reaction are of great synthetic and industrial interest and scientists accept their usefulness and versatility for obtaining arylamines. In this study Ag–N-heterocyclic carbene complexes were used as transmetallation reagents for the synthesis of Pd–N-heterocyclic carbene complexes. The new Pd–N-heterocyclic carbene complexes were characterized using elemental analysis and 1H NMR, 13C NMR and infrared spectroscopies. The crystal structure of one, namely dichlorobis[1,3-bis(2-methylbenzyl)imidazolidin-2-yliden]palladium(II), is presented. The activity of the Pd(II) complexes in the coupling reaction of anilines or amines with bromobenzene was investigated. These complexes exhibited high catalytic activities in the direct synthesis of triarylamines and secondary amines in a single step. Copyright
- Karaca, Emine ?zge,Gürbüz, Nevin,?ahin, Onur,Büyükgüng?r, Orhan,?zdemir, ?smail
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- Oxidative three-component carboamination of vinylarenes with alkylboronic acids
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The three-component carboamination of alkenes is of significant interest due to the ease by which functionalized amines can be produced from readily available chemical building blocks. Previously, a variety of carbon-centered radical precursors have been
- Gockel, Samuel N.,Lee, SangHyun,Gay, Brittany L.,Hull, Kami L.
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- The impact of the nature of amine reactants in the palladium catalyzed conversion of phenol to N-substituted anilines
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Anilines and cyclohexylamines are currently produced from fossil feedstocks. Phenol would be an attractive alternative feedstock that can be obtained from renewable resources. We herein clarify the influence of the amine on the course of the amination of phenol using a hydrogen borrowing strategy. Amines can in this case act as a reductant which can be dehydrogenated to initiate the partial hydrogenation of phenol which is required for the reaction to take place. The nature of the amine reactant can have a larger effect than the presence of additional reductants like sodium formate. The results in this report do not only present a method for the amination of phenol without addition of an extra reductant, but also rationalize the reactivity of amines in their reaction with phenol.
- Tomkins, Patrick,Valgaeren, Carlot,Adriaensen, Koen,Cuypers, Thomas,De Vos, Dirk E.
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- Visible-light-mediated tungsten-catalyzed C-H amination of unactivated alkanes with nitroarenes
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Alkylamines are important motifs in pharmaceutical and material sciences. The existing reports of C-H amination are limited to ammonia, diazo and azide nitrogen sources. This work describes a rapid construction of C-N bonds from accessible nitroarene and alkane feedstock under decatungstate catalysis. A variety of C-H precursors including gaseous, linear, cyclic and benzylic hydrocarbons could adopt this protocol to afford the corresponding alkylamines in high efficiency. [Figure not available: see fulltext.]
- Wang, Qing,Ni, Shengyang,Wang, Xiaochen,Wang, Yi,Pan, Yi
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p. 678 - 685
(2022/02/14)
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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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- Nickel?Copper bimetallic mesoporous nanoparticles: As an efficient heterogeneous catalyst for N-alkylation of amines with alcohols
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A bimetallic catalyst (Ni/Cu-MCM-41) is prepared via co-condensation method. The latter is characterized by Fourier transform infrared (FT-IR), X-ray powder diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), diffuse reflectance spectroscopy (DRS), and nitrogen adsorption–desorption analysis. Catalytic performance of Ni/Cu-MCM-41 is probed in N-alkylation of amines with alcohols through a hydrogen autotransfer process. Noteworthy, this catalytic system appears very efficient for synthesis of a range of secondary and tertiary amines in good to excellent isolated yields. Moreover, the catalyst is successfully recovered and reused four times without notable decrease in its activity.
- Nasresfahani, Zahra,Kassaee, Mohamad Z.
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- Sulfated polyborate: A dual catalyst for the reductive amination of aldehydes and ketones by NaBH4
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An efficient, quick, and environment-friendly one-pot reductive amination of aldehydes or ketones was developed. In ethanol at 70 °C, a imination catalyzed by sulfated polyborate and further reduced by sodium borohydride yields various amines. The present method has many significant benefits, including a shorter reaction time, excellent yields, and a hassle-free, straightforward experimental process. The reaction has a wide range of applications due to its flexibility, including secondary amine for reductive amination.
- Ganwir, Prerna,Chaturbhuj, Ganesh
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- Reductive amination of ketones/aldehydes with amines using BH3N(C2H5)3as a reductant
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Herein, we report the first example of efficient reductive amination of ketones/aldehydes with amines using BH3N(C2H5)3 as a catalyst and a reductant under mild conditions, affording various tertiary and secondary amines in excellent yields. A mechanistic study indicates that BH3N(C2H5)3 plays a dual function role of promoting imine and iminium formation and serving as a reductant in reductive amination. This journal is
- Zou, Qizhuang,Liu, Fei,Zhao, Tianxiang,Hu, Xingbang
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supporting information
p. 8588 - 8591
(2021/09/04)
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- Imine reduction with me2s-bh3
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Although there exists a variety of different catalysts for hydroboration of organic substrates such as aldehydes, ketones, imines, nitriles etc., recent evidence suggests that tetra-coordinate borohydride species, formed by activation, redistribution, or decomposition of boron reagents, are the true hydride donors. We then proposed that Me2S-BH3 could also act as a hydride donor for the reduction of various imines, as similar compounds have been observed to reduce carbonyl substrates. This boron reagent was shown to be an effective and chemoselective hydroboration reagent for a wide variety of imines.
- Kamal, Mohammad M.,Liu, Zhizhou,Vidovi?, Dragoslav,Zhai, Siyuan
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- Palladium supported on magnesium hydroxyl fluoride: An effective acid catalyst for the hydrogenation of imines and N-heterocycles
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Palladium catalysts supported on acidic fluorinated magnesium hydroxide Pd/MgF2-x(OH)x were prepared through precipitation or impregnation methods. Applications to the hydrogenation of various aldimines and ketimines resulted in good catalytic activities at mild temperatures using one atmosphere of hydrogen. Quinolines, pyridines and other N-heterocycles were successfully hydrogenated at higher temperature and hydrogen pressure using low palladium loadings and without the use of any acid additive. Such reactivity trend confirmed the positive effect of the Br?nsted and Lewis acid sites from the fluorinated magnesium hydroxide support resulting in the effective pre-activation of N-heterocycle substrates and therefore in the good catalytic activity of the palladium nanoparticles during the hydrogenations. As demonstrated in the hydrogenation of imines, the catalyst was recycled up to 10 times without either loss of activity or palladium leaching. This journal is
- Agbossou-Niedercorn, Francine,Corre, Yann,Dongare, Mohan K.,Kemnitz, Erhard,Kokane, Reshma,Michon, Christophe,Umbarkar, Shubhangi B.
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supporting information
p. 19572 - 19583
(2021/11/04)
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- A base-free Chan–Lam reaction catalyzed by an easily assembled Cu(II)-carboxylate metal-organic framework
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A new copper(II) metal-organic framework is constructed as a sustainable copper heterogeneous catalyst. Cu-DPTCA, with high catalytic activity, can effectively promote the Chan–Lam coupling reaction of arylboronic acids and amines without adding any base or additive.
- Ma, Ruixuan,Qin, Jianhua,Shi, Lei,Zhang, Xinhai
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p. 795 - 799
(2021/07/06)
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- Mediator-Enabled Electrocatalysis with Ligandless Copper for Anaerobic Chan-Lam Coupling Reactions
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Simple copper salts serve as catalysts to effect C-X bond-forming reactions in some of the most utilized transformations in synthesis, including the oxidative coupling of aryl boronic acids and amines. However, these Chan-Lam coupling reactions have historically relied on chemical oxidants that limit their applicability beyond small-scale synthesis. Despite the success of replacing strong chemical oxidants with electrochemistry for a variety of metal-catalyzed processes, electrooxidative reactions with ligandless copper catalysts are plagued by slow electron-transfer kinetics, irreversible copper plating, and competitive substrate oxidation. Herein, we report the implementation of substoichiometric quantities of redox mediators to address limitations to Cu-catalyzed electrosynthesis. Mechanistic studies reveal that mediators serve multiple roles by (i) rapidly oxidizing low-valent Cu intermediates, (ii) stripping Cu metal from the cathode to regenerate the catalyst and reveal the active Pt surface for proton reduction, and (iii) providing anodic overcharge protection to prevent substrate oxidation. This strategy is applied to Chan-Lam coupling of aryl-, heteroaryl-, and alkylamines with arylboronic acids in the absence of chemical oxidants. Couplings under these electrochemical conditions occur with higher yields and shorter reaction times than conventional reactions in air and provide complementary substrate reactivity.
- Walker, Benjamin R.,Manabe, Shuhei,Brusoe, Andrew T.,Sevov, Christo S.
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supporting information
p. 6257 - 6265
(2021/05/07)
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- Production of alkoxyl-functionalized cyclohexylamines from lignin-derived guaiacols
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The transformation of renewable lignin-based platform chemicals into value-added nitrogen-containing compounds is an emerging strategy for lignin utilization. However, multi-reactive sites on these platform chemicals make it challenging to control the product selectivity, thereby resulting in limited success. In this work, we developed the reductive-coupling of guaiacol, a typical lignin-based platform chemical, with amines and H2 to synthesize methoxy-functionalized cyclohexylamines. It was demonstrated that Pd/C was a very efficient catalyst for this kind of reaction, and high yields of the target products can be obtained. Notably, this methodology can be applied for the reductive-coupling of various guaiacol analogues with amines to synthesize alkoxyl-functionalized cyclohexylamines with high yields. A mechanism study revealed that the reaction occurred through the generation of 2-methoxycyclohexanone and its subsequent reductive amination. This journal is
- Zheng, Bingxiao,Wu, Haihong,Song, Jinliang,Wu, Wei,Mei, Xuelei,Zhang, Kaili,Xu, Caiyun,Xu, Jiao,He, Mingyuan,Han, Buxing
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supporting information
p. 8441 - 8447
(2021/11/17)
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- PH-Mediated Selective Synthesis of N-Allylic Alkylation or N-Alkylation Amines with Allylic Alcohols via an Iridium Catalyst in Water
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Amination of allylic alcohols is an effective approach in the facile synthesis of N-allylic alkylation or N-alkylation amines. Recently, a series of catalysts were devised to push forward this transformation. However, current synthetic methods are typical
- Luo, Nianhua,Zhong, Yuhong,Shui, Hongling,Luo, Renshi
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p. 15509 - 15521
(2021/11/01)
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- Synthesis ofN-aryl amines enabled by photocatalytic dehydrogenation
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Catalytic dehydrogenation (CD)viavisible-light photoredox catalysis provides an efficient route for the synthesis of aromatic compounds. However, access toN-aryl amines, which are widely utilized synthetic moieties,viavisible-light-induced CD remains a significant challenge, because of the difficulty in controlling the reactivity of amines under photocatalytic conditions. Here, the visible-light-induced photocatalytic synthesis ofN-aryl amines was achieved by the CD of allylic amines. The unusual strategy using C6F5I as an hydrogen-atom acceptor enables the mild and controlled CD of amines bearing various functional groups and activated C-H bonds, suppressing side-reaction of the reactiveN-aryl amine products. Thorough mechanistic studies suggest the involvement of single-electron and hydrogen-atom transfers in a well-defined order to provide a synergistic effect in the control of the reactivity. Notably, the back-electron transfer process prevents the desired product from further reacting under oxidative conditions.
- Kim, Jungwon,Kim, Siin,Choi, Geunho,Lee, Geun Seok,Kim, Donghyeok,Choi, Jungkweon,Ihee, Hyotcherl,Hong, Soon Hyeok
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p. 1915 - 1923
(2021/02/22)
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- Sodium anilinide-cyclohexylamide pair: Synthesis, characterization, and hydrogen storage properties
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The lack of efficient hydrogen storage material is one of the bottlenecks for the large-scale implementation of hydrogen energy. Here, a series of new hydrogen storage materials, i.e., anilinide-cyclohexylamide pairs, are proposed via the metallation of an aniline-cyclohexylamine pair. DFT calculations show that the enthalpy change of hydrogen desorption (ΔHd) can be significantly tuned from 60.0 kJ per mol-H2 for the pristine aniline-cyclohexylamine pair to 42.2 kJ per mol-H2 for sodium anilinide-cyclohexylamide and 38.7 kJ per mol-H2 for potassium anilinide-cyclohexylamide, where an interesting correlation between the electronegativity of the metal and the ΔHd was observed. Experimentally, the sodium anilinide-cyclohexylamide pair was successfully synthesised with a theoretical hydrogen capacity of 4.9 wt%, and the hydrogenation and dehydrogenation cycle can be achieved at a relatively low temperature of 150 °C in the presence of commercial catalysts, in clear contrast to the pristine aniline-cyclohexylamine pair which undergoes dehydrogenation at elevated temperatures.
- Jing, Zijun,Yu, Yang,Chen, Ruting,Tan, Khai Chen,He, Teng,Wu, Anan,Pei, Qijun,Chua, Yong Shen,Zheng, Dewen,Zhang, Xi,Ge, Zhixin,Zhang, Fudong,Chen, Ping
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p. 1944 - 1947
(2020/02/22)
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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 0220-0226
(2020/11/10)
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- Scalable preparation of stable and reusable silica supported palladium nanoparticles as catalysts for N-alkylation of amines with alcohols
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The development of nanoparticles-based heterogeneous catalysts continues to be of scientific and industrial interest for the advancement of sustainable chemical processes. Notably, up-scaling the production of catalysts to sustain unique structural features, activities and selectivities is highly important and remains challenging. Herein, we report the expedient synthesis of Pd-nanoparticles as amination catalysts by the reduction of simple palladium salt on commercial silica using molecular hydrogen. The resulting Pd-nanoparticles constitute stable and reusable catalysts for the synthesis of various N-alkyl amines using borrowing hydrogen technology without the use of any base or additive. By applying this Pd-based catalyst, functionalized and structurally diverse N-alkylated amines as well as some selected drug molecules were synthesized in good to excellent yields. Practical and synthetic utility of this Pd-based amination protocol has been demonstrated by upscaling catalyst preparation and amination reactions to several grams-scales as well as recycling of catalyst. Noteworthy, this Pd-catalyst preparation has been up-scaled to kilogram scale and catalysts prepared in both small (1 g) and large-scale (kg) exhibited similar structural features and activity.
- Alshammari, Ahmad S.,Natte, Kishore,Kalevaru, Narayana V.,Bagabas, Abdulaziz,Jagadeesh, Rajenahally V.
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p. 141 - 149
(2020/01/06)
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- In water alkylation of amines with alcohols through a borrowing hydrogen process catalysed by ruthenium nanoparticles
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A simple and environmentally benign procedure for the synthesis of secondary amines in water has been developed. Combining Ru3(CO)12, tetraphenylcyclopentadienone and a small quantity of TGPS-750-M surfactant, primary and secondary alcohols were alkylated at N employing equimolar amounts of aromatic amines in water. The reaction occurs under microwave (MW) dielectric heating with high conversion and high yield. When required, the use of biomass-derived 2-MeTHF or GVL as a co-solvent is possible. Under the influence of MWs, a Ru nanoparticle-nanomicelle combination was formed acting as an effective and recyclable catalyst. This protocol was also employed for "in water" cyclisation to synthesise biologically relevant pyrrolobenzodiazepines (PBDs).
- Risi, Caterina,Calamante, Massimo,Cini, Elena,Faltoni, Valentina,Petricci, Elena,Rosati, Filippo,Taddei, Maurizio
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supporting information
p. 327 - 331
(2020/02/13)
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- Thiazoline-Iridium (III) Complexes and Immobilized Nanomaterials as Selective Catalysts in N-Alkylation of Amines with Alcohols
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In this research, a new series of thiazoline-iridium (III) complexes (4–7) derived from cysteine were prepared and fully characterized by conventional methods. The molecular structure of complex 5 was also determined by single-crystal X-ray diffraction. These complexes were evaluated as catalysts for hydrogen-borrowing reactions of amines with alcohols. In particular, complex 5 showed the best activity as catalyst. Various amines have been alkylated with alcohols affording moderate to good yield (33–99%). Moreover, the immobilized nanomaterials (M1,2) were fabricated by sonication process from the best catalyst 5 with the multi-walled carbon nanotubes (MWCNTs) and graphene oxide (GO), respectively, and characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray (EDX) spectroscopy, and inductively coupled plasma-mass spectrometry (ICP-MS). The M1,2 nanomaterials were also tested as catalysts in model catalytic reaction for N-alkylation. The M1 nanomaterial showed significantly higher activity than the M2 nanomaterial. The M1 catalyst was recovered by filtration and reused for four catalytic cycles with high conversion (99%, 97%, 96%, and 86%).
- Denizalt?, Serpil,Dayan, Serkan,Günnaz, Salih,?ahin, Ertan
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- AlCl3 immobilized on silicic acid as efficient Lewis acid catalyst for highly selective preparation of dicyclohexylamine from the vapor phase hydroamination of cyclohexene with cyclohexylamine
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An efficient and stable Lewis acid catalyst silicic acid (SA)-immobilized AlCl3 (AlCl3-SA) has been successfully prepared by the chemical bonding method in this work. The results indicated that the immobilized 15percentAlCl3-SA exhibited excellent catalytic performance and stability in the vapor phase hydroamination of cyclohexene with cyclohexylamine. 58.5percent cyclohexene conversion with 98.7percent selectivity to dicyclohexylamine was still maintained after running for over 150 h, and the space time yield of dicyclohexylamine was 142.6 mol/h·m3. The developed AlCl3-SA catalyst had the advantages of low cost and long-time stable activity. Maybe this work provides a promising approach for hydroamination of olefins to amines.
- Ai, Qiuhong,Jian, Jian,Liu, Pingle,Luo, He'an,Wen, Jingbin,You, Kuiyi,Zhao, Fangfang
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- Visible Light-Mediated (Hetero)aryl Amination Using Ni(II) Salts and Photoredox Catalysis in Flow: A Synthesis of Tetracaine
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We report a visible light-mediated flow process for C-N cross-coupling of (hetero)aryl halides with a variety of amine coupling partners through the use of a photoredox/nickel dual catalyst system. Compared to the method in batch, this flow process enables a broader substrate scope, including less-activated (hetero)aryl bromides and electron-deficient (hetero)aryl chlorides, and significantly reduced reaction times (10 to 100 min). Furthermore, scale up of the reaction, demonstrated through the synthesis of tetracaine, is easily achieved, delivering the C-N cross-coupled products in consistently high yield of 84% on up to a 10 mmol scale.
- Park, Boyoung Y.,Pirnot, Michael T.,Buchwald, Stephen L.
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p. 3234 - 3244
(2020/02/04)
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- COPOLYMER, PHOTOSENSITIVE RESIN COMPOSITION COMPRISING THE SAME AND COLOR FILTER
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The present invention relates to a copolymerization polymer which is derived from a compound represented by chemical formula 1 and is usable as a dye, a photosensitive resin composition comprising the copolymerization polymer as a colorant, and to a color filter manufactured by using the photosensitive resin composition. In the chemical formula 1, each substituent group is the same as defined in the specification.
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Paragraph 0372-0376
(2020/05/20)
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- Design, Synthesis, and Structure-Activity Relationship Studies of Novel Indolyalkylpiperazine Derivatives as Selective 5-HT1A Receptor Agonists
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5-HT1A receptor (5-HT1AR) agonists have been implicated in the treatment of a variety of central nervous system (CNS) diseases such as depression and anxiety, et al. Based on our previously found compound FW01 (Ki = 51 ± 16 nM) obtained by virtual screening, a series of FW01 derivatives were designed and synthesized by the modification of the amide tail group as well as indole headgroup of FW01. SAR exploration found that amide tail group and indole headgroup play pivotal roles in determining the binding affinity and selectivity on dopamine and serotonin receptor subtypes. Among all tested compounds, 9_24 has a Ki value of 5 ± 0.6 nM with a good selectivity toward 5-HT1AR. The [35S] GTPγS assay showed that 9_24 is a full agonist toward 5-HT1AR with an EC50 value of 0.059 nM, which shows 266.2 and 146.4-fold selectivity to 5-HT2A and D3 respectively. Molecular dynamics simulations and molecular docking studies with 5-HT1AR-9_24 were performed to disclose the mechanism of its high activity and selectivity. Finally, a detailed stepwise 9_24 induced signal transduction mechanism of 5-HT1AR is proposed.
- Wang, Wenli,Zheng, Lan,Li, Wei,Zhu, Chen,Peng, Weiqing,Han, Bing,Fu, Wei
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p. 235 - 248
(2020/02/18)
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- Pd/C Catalyzed selective hydrogenation of nitrobenzene to cyclohexanone oxime in the presence of NH2OH·HCl: Influence of the operative variables and insights on the reaction mechanism
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We studied the influence of temperature, solvent, pressure, catalysts type on the selectivity of nitrobenzene hydrogenation to cyclohexanone oxime (COX) in the presence of NH2OH. The best reaction conditions are: pressure 0.8 MPa, temperature 333 K, solvent ethers, and catalyst Pd/C5%. Other hydrogenation metal catalysts did not give comparable results. The amount of Pd/C influences the yield in COX, which rises above to 90 % at the highest load. The reaction profile shows that aniline is the reaction intermediate. Indeed, aniline as a substrate gives COX, though in lower yield than that achieved employing nitrobenzene. The NH2OH parallel hydrogenation to NH4Cl, influences positively the selectivity to COX. It has been observed that COX, cyclohexanone and N-cyclohexylideneaniline are in equilibrium in the reaction solution and all likely derive from nucleophilic substitutions to a common imine intermediate formed on the Pd surface, whose high activity does not need any further metal catalyst.
- Pietrobon, L.,Pontello, R.,Ronchin, L.,Sadraoui, C.,Tosetto, C.,Vavasori, A.
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- Phyllosilicate-derived Nickel-cobalt Bimetallic Nanoparticles for the Catalytic Hydrogenation of Imines, Oximes and N-heteroarenes
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The development of cost-effective, noble metal-free catalytic systems for the hydrogenation of unsaturated aliphatic, aromatic, and heterocyclic compounds is fundamental for future valorization of general feedstock. With this aim, we report here the preparation of highly dispersed bimetallic Ni/Co nanoparticles (NPs), by a one-pot deposition-precipitation of Ni and Co phases onto mesoporous SBA-15 silica. By adjusting the chemical composition in the starting mixture, three supported catalysts with different Ni to Co weight ratios were obtained, which were further subjected to treatments under reducing conditions at high temperatures. Characterization of the resulting solids evidenced a homogenous distribution of Ni and Co elements forming the NPs, the best results being obtained for Ni/Co-2 : 2 samples, for which 50 wt.percent Ni–50 wt.percent Co NPs are found located on the surface of the residual phyllosilicate. Ni/Co-2 : 2, presenting the best performances for the hydrogenation of 2-methyl-quinoline, was further evaluated in the catalytic hydrogenation of selected imines, oximes and N-heteroarenes. Due to the high dispersion of bimetallic Ni?Co NPs, excellent properties (activity and selectivity) in the conversion of the selected substrates are reported.
- Ciotonea, Carmen,Hammi, Nisrine,Dhainaut, Jérémy,Marinova, Maya,Ungureanu, Adrian,El Kadib, Abdelkrim,Michon, Christophe,Royer, Sébastien
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p. 4652 - 4663
(2020/08/19)
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- Tandem Photoredox and Copper-Catalyzed Decarboxylative C(sp3)-N Coupling of Anilines and Imines Using an Organic Photocatalyst
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An organic photoredox catalyst, 4CzIPN, was used in combination with a copper catalyst, CuCl, to effect decarboxylative C(sp3)-N coupling. The coupling worked with both anilines and imines as nitrogen sources and could be used to prepare a variety of alkyl amines from readily available alkyl carboxylic acids.
- Barzanò, Guido,Mao, Runze,Garreau, Marion,Waser, Jerome,Hu, Xile
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p. 5412 - 5416
(2020/07/14)
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- Method to convert lignin 4-O-5 diaryl ethers and their model compounds into organic chemicals
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It is provided a method of converting a diaryl ether source such as lignin and/or polyphenylene oxide (PPO) containing 4-O-5 linkages and an inorganic chemical such as ammonia into an organic compound, comprising reacting said diaryl ether source with the inorganic chemical in presence of a catalyst, preferably palladium, transforming the 4-O-5 linkages of said diaryl ether source into the organic compound. It is provided a palladium-catalyzed synthesis of aniline derivatives from 4-O-5 linkage lignin model compounds and cheap industrial inorganic chemical ammonia via dual C(Ar)—O bond cleavage.
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Paragraph 6-9
(2020/09/18)
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- Imidazole-directed fabrication of three polyoxovanadate-based copper frameworks as efficient catalysts for constructing C-N bonds
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A synthetic pathway for the directed preparation of three novel polyoxovanadate-based copper frameworks (POVCFs), i.e., [Cu0.5(1-ipIM)2]2[V4O11] (POVCF 1), [Cu(1-ipIM)2](VO3)2 (POVCF 2) and [Cu(1-pIM)4](HpIM)4[V10O28] (POVCF 3) (1-ipIM = 1-isopropylimidazole; 1-pIM = 1-propylimidazole) using bifunctional imidazole molecules as organic ligands and base has been developed. Systematic studies revealed that the variable base enviroment in the reaction is the key step in the preparation of 1D to 3D supermolecular networks of POVCFs 1-3. Single crystal X-ray diffraction analyses demonstrated that the Cu2+ atoms of POVCFs 1-2 were coordinated with four imidazole derivative molecules and two different polyoxovanadate {[V4O11]2- and [V10O28]6-} clusters, respectively, exhibiting a [CuN4O2] binding set and a distorted octahedral geometry. Specifically, POVCF 1 exhibited adjacent [V4O11]2- that dangle up and down arranged in a parallel 2D network and further coordinated with [Cu(1-ipIM)4]2+ to form a 3D supramolecular structure. However, POVCF 3 presented one tetrahedral coordinated vanadium atom and one four-coordinated copper atom and they further gave rise to a 1D network by the Cu-O and V-O bonds. More importantly, these POVCFs were further studied in the construction of C-N bond reactions of primary amines under mild conditions, and it was found that POVCF 1 displayed efficient heterogeneous catalytic activities in the Chan-Lam reaction (yields up to 89%). This journal is
- Gong, Shuwen,Gu, Yuxiao,Huang, Xianqiang,Li, Jikun,Li, Qiang,Qi, Yuquan,Shen, Guodong
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p. 10970 - 10976
(2020/09/02)
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- One-pot synthesis of pyrrolidones from levulinic acid and amines/nitroarenes/nitriles over the Ir-PVP catalyst
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The synthesis of pyrrolidones via reductive amination of levulinic acid with aniline was examined over polypyrrolidone-stabilized metal nanoparticle catalysts. Among them, Ir metal was the most effective and applicable for the reductive amination of levulinic acid with nitroarenes/nitriles. Importantly, this catalyst was used for the one-pot synthesis of the anti-inflammatory drug indoprofen from 2-formylbenzoic acid and 2-(4-nitrophenyl)propanoic acid.
- Chaudhari, Chandan,Nagaoka, Katsutoshi,Nishida, Yoshihide,Sato, Katsutoshi,Shiraishi, Masaya
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supporting information
p. 7760 - 7764
(2020/11/27)
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- Visible-Light-Enabled Direct Decarboxylative N-Alkylation
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The development of efficient and selective C?N bond-forming reactions from abundant feedstock chemicals remains a central theme in organic chemistry owing to the key roles of amines in synthesis, drug discovery, and materials science. Herein, we present a dual catalytic system for the N-alkylation of diverse aromatic carbocyclic and heterocyclic amines directly with carboxylic acids, by-passing their preactivation as redox-active esters. The reaction, which is enabled by visible-light-driven, acridine-catalyzed decarboxylation, provides access to N-alkylated secondary and tertiary anilines and N-heterocycles. Additional examples, including double alkylation, the installation of metabolically robust deuterated methyl groups, and tandem ring formation, further demonstrate the potential of the direct decarboxylative alkylation (DDA) reaction.
- Arman, Hadi D.,Dang, Hang T.,Haug, Graham C.,Larionov, Oleg V.,Nguyen, Viet D.,Nguyen, Vu T.,Vuong, Ngan T. H.
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supporting information
p. 7921 - 7927
(2020/04/10)
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- Ni-Catalyzed reductive amination of phenols with ammonia or amines into cyclohexylamines
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Phenol and its derivatives, which naturally occur in lignocellulose, can be considered as a renewable feedstock not only for aromatic, but also for alicyclic compounds, such as primary and N-substituted cyclohexylamines. So far, the latter are mostly produced from non-renewable starting materials like benzene via problematic nitration/reduction or cross-coupling routes. Herein, an efficient reductive amination of phenol with ammonia or amines is demonstrated, for the first time without the need for rare and expensive noble metals and without using any additives. Various supported Ni catalysts were screened and we elucidated the influence of the key parameters, including the acid-base properties of the supporting material. Acquired knowledge was then applied to different phenol-ammonia/amine combinations, resulting in the synthesis of various primary, secondary and tertiary cyclohexylamines in fair to very high yields.
- Cuypers, Thomas,Morias, Thomas,Windels, Simon,Marquez, Carlos,Van Goethem, Cédric,Vankelecom, Ivo,De Vos, Dirk E.
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supporting information
p. 1884 - 1893
(2020/04/07)
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- Direct Catalytic Decarboxylative Amination of Aryl Acetic Acids
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The decarboxylative coupling of a carboxylic acid with an amine nucleophile provides an alternative to the substitution of traditional organohalide coupling partners. Benzoic and alkynyl acids may be directly aminated by oxidative catalysis. In contrast, methods for intermolecular alkyl carboxylic acid to amine conversion, including amidate rearrangements and photoredox-promoted approaches, require stoichiometric activation of the acid unit to generate isocyanate or radical intermediates. Reported here is a process for the direct chemoselective decarboxylative amination of electron-poor arylacetates by oxidative Cu catalysis. The reaction proceeds at (or near) room temperature, uses native carboxylic acid starting materials, and is compatible with protic, electrophilic, and other potentially complicating functionality. Mechanistic studies support a pathway in which ionic decarboxylation of the acid generates a benzylic nucleophile which is aminated in a Chan–Evans–Lam-type process.
- Kong, Duanyang,Moon, Patrick J.,Bsharat, Odey,Lundgren, Rylan J.
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supporting information
p. 1313 - 1319
(2019/12/15)
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- Continuous Synthesis of Aryl Amines from Phenols Utilizing Integrated Packed-Bed Flow Systems
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Aryl amines are important pharmaceutical intermediates among other numerous applications. Herein, an environmentally benign route and novel approach to aryl amine synthesis using dehydrative amination of phenols with amines and styrene under continuous-flow conditions was developed. Inexpensive and readily available phenols were efficiently converted into the corresponding aryl amines, with small amounts of easily removable co-products (i.e., H2O and alkanes), in multistep continuous-flow reactors in the presence of heterogeneous Pd catalysts. The high product selectivity and functional-group tolerance of this method allowed aryl amines with diverse functional groups to be selectively obtained in high yields over a continuous operation time of one week.
- Ichitsuka, Tomohiro,Kobayashi, Shū,Koumura, Nagatoshi,Sato, Kazuhiko,Takahashi, Ikko
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p. 15891 - 15896
(2020/07/13)
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- A Novel Modified Cross-Coupling of Phenols and Amines Using Dichloroimidazolidinedione (DCID)
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Phenols are considered as an ideal alternative to aryl halides as coupling partners in cross-coupling reactions. In the present work a copper-catalyzed cross-coupling of phenols with various aromatic and aliphatic amines for the synthesis of secondary aryl amines using dichloroimidazolidinedione (DCID) as a new and efficient activating agent has been developed. Substituted phenols were compatible with the standard reaction conditions. The two proposed mechanisms, which are based on the oxidation addition of copper with Ar-OMCID (MCID: Monochloroimidazolidinedione), are also discussed.
- Madankar, Kamelia,Mokhtari, Javad,Mirjafary, Zohreh
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supporting information
p. 1725 - 1729
(2020/09/01)
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- Nickel-Catalyzed Amination of Aryl Thioethers: A Combined Synthetic and Mechanistic Study
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Herein, we report a nickel-1,2-bis(dicyclohexylphosphino)ethane (dcype) complex for the catalytic Buchwald-Hartwig amination of aryl thioethers. The protocol shows broad applicability with a variety of different functional groups tolerated under the catalytic conditions. Extensive organometallic and kinetic studies support a nickel(0)-nickel(II) pathway for this transformation and revealed the oxidative addition complex as the resting state of the catalytic cycle. All the isolated intermediates have proven to be catalytically and kinetically competent catalysts for this transformation. The fleeting transmetalation intermediate has been successfully synthesized through an alternative synthetic organometallic pathway at lower temperature, allowing for in situ NMR study of the C-N bond reductive elimination step. This study addresses key factors governing the mechanism of the nickel-catalyzed Buchwald-Hartwig amination process, thus improving the understanding of this important class of reactions.
- Bismuto, Alessandro,Delcaillau, Tristan,Müller, Patrick,Morandi, Bill
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p. 4630 - 4639
(2020/05/19)
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- C–N Cross-coupling Reactions of Amines with Aryl Halides Using Amide-Based Pincer Nickel(II) Catalyst
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Abstract: An approach to C–N cross-coupling reactions of aryl halides with amines in the presence of an amide-based pincer nickel(II) catalyst (2) is described. For 3?h reactions at 110?°C with 0.2?mol% catalyst, aryl bromides gave higher turnover numbers (TON) than the corresponding chlorides or iodides. Both primary and secondary amines could be used with the former giving higher TON. However, sterically hindered amines showed lower TON. In elucidating the mechanism of this nickel complex-catalyzed C–N cross coupling reaction it was found that the rate of reaction was unchanged in the presence of radical quenchers and a plausible Ni(I)–Ni(III) pathway is proposed. Graphic Abstract: [Figure not available: see fulltext.]Nickel pincer catalyst proved to be excellent catalyst for the C-N cross-coupling reaction with the high turnover number (TON) for 1° and 2° amines and different nonactivated aryl halides under optimum conditions.
- Albkuri, Yahya M.,RanguMagar, Ambar B.,Brandt, Andrew,Wayland, Hunter A.,Chhetri, Bijay P.,Parnell, Charlette M.,Szwedo, Peter,Parameswaran-Thankam, Anil,Ghosh, Anindya
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p. 1669 - 1678
(2019/12/27)
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- Efficient One-Pot Reductive Aminations of Carbonyl Compounds with Aquivion-Fe as a Recyclable Catalyst and Sodium Borohydride
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A one-pot reductive amination of aldehydes and ketones with NaBH4 was developed with a view to providing efficient, economical and greener synthetic conditions. A recyclable iron-based Lewis catalyst, Aquivion-Fe, was used to promote imine formation in cyclopentyl methyl ether, followed by the addition of a small amount of methanol to the reaction mixture to enable C=N reduction by NaBH4. The protocol, applied to a wide number of amines and carbonyl compounds, resulted in ever complete conversion of these latter with excellent chemoselectivity towards the expected amination products in the most cases. Isolated yields, determined for a selection of the screened substrates, were found consistent with the previously obtained conversion and selectivity data. Cinacalcet, an important active pharmaceutical ingredient, was efficiently prepared by the title procedure.
- Airoldi, Veronica,Piccolo, Oreste,Roda, Gabriella,Appiani, Rebecca,Bavo, Francesco,Tassini, Riccardo,Paganelli, Stefano,Arnoldi, Sebastiano,Pallavicini, Marco,Bolchi, Cristiano
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supporting information
p. 162 - 168
(2019/12/11)
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- Borrowing Hydrogen-Mediated N-Alkylation Reactions by a Well-Defined Homogeneous Nickel Catalyst
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We report herein a well-defined and bench-stable azo-phenolate ligand-coordinated nickel catalyst which can efficiently execute N-alkylation of a variety of anilines by alcohol. We demonstrate that the redox-active azo ligand can store hydrogen generated during alcohol oxidation and redelivers the same to an in-situ-generated imine bond to result in N-alkylation of amines. The reaction has wide scope, and a large array of alcohols can directly couple to a variety of anilines. Mechanistic studies including deuterium labeling to the substrate establishes the borrowing hydrogen method from alcohols and pinpoints the crucial role of the redox-active azo moiety present on the ligand backbone. Isolation of the ketyl intermediate in its trapped form with a radical quencher and higher kH/kD for the alcohol oxidation step suggest altogether a hydrogen-atom transfer (HAT) to the reduced azo backbone to pave alcohol oxidation as opposed to the conventional metal-ligand bifunctional mechanism. This example clearly demonstrates that an inexpensive base metal catalyst can accomplish an important coupling reaction with the help of a redox-active ligand backbone.
- Bains, Amreen K.,Kundu, Abhishek,Yadav, Sudha,Adhikari, Debashis
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p. 9051 - 9059
(2019/10/02)
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- General synthesis of N-Alkylation of amines with secondary alcohols via hydrogen autotransfer
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Direct catalytic N-alkylation of amines with secondary alcohols via hydrogen autotransfer (HA) strategy is very challenging and has been scarcely reported, even under precious metal catalysis. Herein, an efficient N-alkylation of amines, including benzyla
- Subaramanian, Murugan,Midya, Siba P.,Ramar, Palmurukan M.,Balaraman, Ekambaram
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supporting information
p. 8899 - 8903
(2019/11/14)
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- A Highly Active PN3 Manganese Pincer Complex Performing N-Alkylation of Amines under Mild Conditions
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A highly active Mn(I) catalyst based on a nonsymmetric PN3-ligand scaffold for the N-alkylation of amines with alcohols utilizing the borrowing hydrogen methodology is reported. A broad range of anilines and the more challenging aliphatic amines were alkylated with primary and secondary alcohols. Moreover, the combination of low catalyst loadings and mild reaction conditions provides high efficiency for this atom-economic transformation.
- Homberg, Leonard,Roller, Alexander,Hultzsch, Kai C.
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supporting information
(2019/05/07)
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- Recyclable bimetallic CuMoO4 nanoparticles for C-N cross-coupling reaction under mild conditions
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Herein we disclosed inexpensive copper(ii) bimetallic CuMoO4 nanoparticles for the C-N cross-coupling reaction of alkyl and aryl amines with haloarenes. The reaction proceeds under mild and ligand free conditions. The catalyst is recyclable and effective for a wide range of amines and haloarenes. Here, the efficiency of the Cu(ii) catalyst is increased by doping molybdenum metal. The bimetallic nanoparticles are anticipated to proceed via normal oxidative addition and reductive eliminations.
- Panigrahi, Reba,Panda, Subhalaxmi,Behera, Pradyota Kumar,Sahu, Santosh Kumar,Rout, Laxmidhar
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supporting information
p. 19274 - 19278
(2019/12/24)
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- COMPOUND, PHOTOSENSITIVE RESIN COMPOSITION COMPRISING THE SAME AND COLOR FILTER
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The present invention provides a dye compound represented by chemical formula 1, a photosensitive resin composition comprising the dye compound as a coloring agent, and a color filter manufactured by using the photosensitive resin composition. The dye com
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Paragraph 0347-0351
(2019/05/28)
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- PHOTOSENSITIVE RESIN COMPOSITION AND PHOTOSENSITIVE RESIN LAYER USING THE SAME, ADHESIVE COMPOSITION AND ADHESIVE FILM USING THE SAME, COLOR FILTER, POLARIZING PLATE AND OPTICAL DISPLAY DEVICE
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The present invention is related to a photosensitive resin composition and an adhesive composition including a compound represented by Chemical Formula 1, a photosensitive resin layer and an adhesive film manufactured using the composition, a color filter
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Paragraph 0089; 0190
(2020/02/18)
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- Band-Gap Narrowing of Highly Stable Heterogeneous ZrO2–ZnO Nanocomposites for the Reductive Amination of Carbonyl Compounds with Formic Acid and Triethylamine
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The band gap of a material can be affected by factors such as size, doping materials, and oxygen vacancies. The decrease in band gap and change in state of ZrO2 with the addition of ZnO indicates interfacial interactions between ZrO2 and ZnO in the nanocomposites (NCs), which is further confirmed by the observed shift of the peaks in the Raman spectra. Heterobimetallic ZrO2–ZnO NCs were synthesized through a sustainable green approach by using sucrose isolated from Angelica gigas Nakai root extract. The highly stable NCs displayed excellent catalytic activity for reductive amination of carbonyl compounds utilizing HCO2H/(CH3CH2)3N as a hydrogen source. The high catalytic performance of the NCs was closely correlated with the narrow band gap and synergistic effect of ZrO2 with ZnO in the NCs.
- Mishra, Kanchan,Kim, Sung Hong,Lee, Yong Rok
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p. 881 - 889
(2019/02/01)
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- H2 Activation by Non-Transition-Metal Systems: Hydrogenation of Aldimines and Ketimines with LiN(SiMe3)2
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In recent years, H2 activation at non-transition-metal centers has met with increasing attention. Here, a system in which H2 is activated and transferred to aldimines and ketimines using substoichiometric amounts of lithium bis(trimethylsilyl)amide is reported. Notably, the reaction tolerates the presence of acidic protons in the α-position. Mechanistic investigations indicated that the reaction proceeds via a lithium hydride intermediate as the actual reductant.
- Elliott, Daniel C.,Marti, Alex,Mauleón, Pablo,Pfaltz, Andreas
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supporting information
p. 1918 - 1922
(2019/01/16)
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- Oxidative Rearrangement of Primary Amines Using PhI(OAc)2 and Cs2CO3
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An oxidative rearrangement of primary amines mediated by a hypervalent iodine(III) reagent is herein reported. The combination of PhI(OAc)2 and Cs2CO3 proves highly efficient at inducing the direct 1,2-C to N migration of primary amines, which can be applied to the preparation of both acyclic and cyclic amines. A mechanistic study shows that the rearrangement proceeds via a concerted mechanism.
- Yamakoshi, Wataru,Arisawa, Mitsuhiro,Murai, Kenichi
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supporting information
(2019/05/08)
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- Catalytic Hydrogenation of Carboxamides with a Bifunctional Cp Ru Catalyst Bearing an Imidazol-2-ylidene with a Protic Aminoethyl Side Chain
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Synthesis of a Cp Ru complex bearing an NH 2 -functionalized N -heterocyclic carbene (C-N H) was achieved by treatment of CpRuBr(isoprene) with an equimolar amount of a silver complex, which was generated from Ag 2 O and 1-(2-aminoethyl)-3-methylimidazolium bromide, in CH 3 CN at room temperature. The new CpRuBr(C-N H) complex showed a higher catalytic performance than the related CpRuCl(P-N H) and CpRuCl(N-N H) complexes. In the reaction of N -arylcarboxamides, the amine products were obtained in satisfactory yields under mild temperature conditions.
- Ikariya, Takao,Kawano, Teruhiro,Kayaki, Yoshihito,Watari, Ryo
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p. 2542 - 2547
(2019/06/08)
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- Nickel-catalyzed N-arylation of amines with arylboronic acids under open air
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In this study, a well-defined, novel NHC-Ni complex was developed and used to catalyze the N-arylation of alkyl- and arylamines with arylboronic acids in a rare version of Chan-Lam coupling. Although the same coupling using copper catalysts has been widely studied, the nickel-catalyzed version is rare and normally requires 10–20 mol% catalyst loading. This novel NHC-Ni complex in combination with 4,4′-dimethyl-2,2′-bipyridine, however, proved to be an effective catalyst that lowered the required catalyst loading to only 2.0 mol%.
- Ando, Shin,Hirota, Yurina,Matsunaga, Hirofumi,Ishizuka, Tadao
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supporting information
p. 1277 - 1280
(2019/04/10)
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- Replacing sulfonate by carboxylate: Application of pyridyliminocarboxylato copper(II) complexes in rac-lactide polymerization and Chan-Evans-Lam coupling
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Copper(II) complexes carrying pyridylmethyleneaminobenzoate or-propanoate ligands, LCuX, were prepared in one-pot reactions from pyridinecarboxaldehyde, aminobenzoic acid or β-alanine, and CuX2 (X = Cl, NO3, OAc, or OTf). All complexes were characterized by single-crystal X-ray diffraction studies and formed either dimers, tetramers, or coordination polymers. Attempted preparation of the respective alkoxide complexes, LCu(OR), was unsuccessful, but use of LCuX/NaOMe mixtures in rac-lactide polymerization indicated under some conditions coordination-insertion polymerization via a copper alkoxide as the mechanism. The complexes performed poorly in rac-lactide polymerization, showing low activities (12 h to completion at 140 °C), low to moderate heterotacticity (Pr = 0.6-0.8), and poor polymer molecular weight control (intramolecular transesterification). They were competent catalysts for Chan-Evans-Lam couplings with phenylboronic acid, without any indication of side reactions such as deboration or aryl homocoupling. The complexes were active in undried methanol, without addition of base, ligand, or molecular sieves. Aniline, n-octylamine, and cyclohexylamine were coupled quantitatively under identical reaction conditions. There is only little influence of the anion on activities (less than a factor of 2) but a strong influence on induction periods. The complexes were not active in CEL coupling with alcohols, phenols, or alkylboronic acids.
- Hardouin Duparc, Valérie,Dimeck, Clémentine,Schaper, Frank
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p. 178 - 190
(2019/03/11)
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- Iron-Catalyzed/Mediated C-N Bond Formation: Competition between Substrate Amination and Ligand Amination
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Iron catalyzed carbon-nitrogen bond formation reactions of a wide variety of nucleophiles and aryl halides using well-defined iron-complexes featuring redox noninnocent 2-(arylazo)-1,10-phenanthroline (L1) ligands are reported. Besides substrate centered C-N coupling, C-N bond formation reactions were also observed at the ortho- and para-positions of the phenyl ring of the coordinated azo-aromatic scaffolds affording new tetradentate ligands, 2-N-aryl-(2-arylazo)-1,10-phenanthroline (L2), and tridentate ligands, 4-N-aryl-(2-arylazo)-1,10-phenanthroline (L3), respectively. Control experiments and mechanistic studies reveal that the complex [FeL1Cl2] (1) undergoes in situ reduction during the catalytic reaction to produce the monoanionic complex [1]-, which then acts as the active catalyst. The metal (iron) and the coordinated ligand were found to work in a cooperative manner during the transfer processes involved in the fundamental steps of the catalytic cycle. Detailed experimental and theoretical (DFT) studies were performed to get insight into the competitive substrate versus ligand centered amination reactions.
- Sinha, Suman,Sikari, Rina,Sinha, Vivek,Jash, Upasona,Das, Siuli,Brand?o, Paula,Demeshko, Serhiy,Meyer, Franc,De Bruin, Bas,Paul, Nanda D.
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p. 1935 - 1948
(2019/01/25)
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- New Insights into the Reaction Capabilities of Ionic Organic Bases in Cu-Catalyzed Amination
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The application of ionic organic bases in the copper-catalyzed amination reaction (Ullmann reaction) has been studied at room temperature, with sub-mol-% catalyst loadings, and with more challenging amines at elevated temperatures. The cation present in the base has been shown to have little effect on the reaction at standard catalyst and ancillary ligand loadings, whereas the choice of anion is crucial for good reactivity. A substrate scope carried out at room temperature with the best performing bases, TBAM and TBPM, showed both bases to be highly effective under these mild reaction conditions. Moreover, under sub-mol % catalyst loadings and room temperature conditions, TBPM gave good to excellent yields for a number of different amines and functionalized aryl iodides (14 examples). However, reactions involving more challenging amines gave little or no yield. By using more forceful conditions (120 °C) moderate to excellent yields of cross-coupled products containing more challenging amines was achievable using TBPM and to a lesser extent with TBAM. As part of this work a study on the stability of the organic bases at 120 °C was undertaken. TBAM is shown to decompose to give nBu3N and mono-butylmalonate at higher temperatures, and this can be correlated to a decrease in performance in the coupling reaction. The phosphonium cations in TBPM did not undergo analogous reactivity but were shown instead to experience some degree of deprotonation at the α-CH2 to generate phosphonium ylides. This however did not lead to a significantly degradation in the activity of the TBPM in the cross-coupling reaction.
- Lo, Quintin A.,Sale, David,Braddock, D. Christopher,Davies, Robert P.
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p. 1944 - 1951
(2019/02/19)
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