- Visible-light-mediated tungsten-catalyzed C-H amination of unactivated alkanes with nitroarenes
-
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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- Iodine-mediated 1,2-aryl migration of primary benzhydryl amines
-
An iodine-mediated 1,2-aryl migration reaction of primary benzhydryl amines under transition metal-free conditions has been achieved. The crude imines generated by this rearrangement reaction can be directly transformed into various aromatic secondary ami
- Chang, Junbiao,Du, Yangxu,Hao, Wei,Hou, Jiao,Lu, Qing,Yu, Wenquan
-
supporting information
p. 16223 - 16226
(2021/09/22)
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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)
-
- Regio- And Stereoselective (S N2) N -, O -, C - And S -Alkylation Using Trialkyl Phosphates
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Bimolecular nucleophilic substitution (S N 2) is one of the most well-known fundamental reactions in organic chemistry to generate new molecules from two molecules. In principle, a nucleophile attacks from the back side of an alkylating agent having a suitable leaving group, most commonly a halide. However, alkyl halides are expensive, very harmful, toxic and not so stable, which makes them problematic for laboratory use. In contrast, trialkyl phosphates are inexpensive, readily accessible and stable at room temperature, under air, and are easy to handle, but rarely used as alkylating agents in organic synthesis. Here, we describe a mild, straightforward and powerful method for nucleophilic alkylation of various N -, O -, C - and S -nucleophiles using readily available trialkyl phosphates. The reaction proceeds smoothly in excellent yield, and quantitative yield in many cases, and covers a wide range of substrates. Further, the rare stereoselective transfer of secondary alkyl groups has been achieved with inversion of configuration of chiral centers (up to 98% ee).
- Banerjee, Amit,Hattori, Tomohiro,Yamamoto, Hisashi
-
-
- The synthesis and structure of an amazing and stable carbonized material Cu-PC@OFM and its catalytic applications in water with mechanism explorations
-
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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- Preparation of alkylated compounds using the trialkylphosphate
-
[Problem] trialkylphosphate strong base used reaction agent, a carboxylic acid, a ketone, an aldehyde, amine, amide, thiol, ester or Grignard reagent to a variety of substrates, and/or high efficiency to generate a highly stereoselective alkylation reaction, the alkylated compounds capable of producing new means. [Solution] was used as the alkylating agent in the alkylation of compound trialkylphosphate, strongly basic reaction production use. [Drawing] no
- -
-
Paragraph 0173-0174; 0176
(2021/11/02)
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- Iron-catalysed 1,2-aryl migration of tertiary azides
-
1,2-Aryl migration of α,α-diaryl tertiary azides was achieved by using the catalytic system of FeCl2/N-heterocyclic carbene (NHC) SIPr·HCl. The reaction generated aniline products in good yields after one-pot reduction of the migration-resultant imines.
- Wei, Kaijie,Yang, Tonghao,Chen, Qing,Liang, Siyu,Yu, Wei
-
supporting information
p. 11685 - 11688
(2020/10/19)
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- Titanium-Catalyzed Hydroaminoalkylation of Ethylene
-
The first examples of titanium-catalyzed hydroaminoalkylation reactions of ethylene with secondary amines are presented. The reactions can be achieved with various titanium catalysts and they do not require the use of high pressure equipment. In addition, the first solid-state structure of a titanapyrrolidine that is formed by insertion of an alkene into the Ti?C bond of a titanaaziridine is reported.
- Rosien, Michael,T?ben, Iris,Schmidtmann, Marc,Beckhaus, Rüdiger,Doye, Sven
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supporting information
p. 2138 - 2142
(2020/02/05)
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- Synthesis and application of axially chiral biscarbolines with functional N-O and sulfone for 1,2-transfer hydrogenations of ketimines
-
A series of axially chiral biscarboline-based sulfones were synthesized from L-tryptophane and applied for enantioselective 1,2-transfer hydrogenations of ketimines using trichlorosilane. The catalyst 4e, which had a tertiary butyl group, exhibited a good conversion and high enantioselectivities up to 96%ee in the series of reactions.
- Xing, Yongfei,Wu, Shijie,Dong, Mengxian,Wang, Jie,Liu, Li,Zhu, Huajie
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supporting information
(2019/08/08)
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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
-
supporting information
p. 3255 - 3258
(2019/09/17)
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- Chiral Br?nsted Acid-Catalyzed Metal-Free Asymmetric Direct Reductive Amination Using 1-Hydrosilatrane
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The asymmetric direct reductive amination of prochiral ketones with aryl amines using 1-hydrosilatrane with a chiral Br?nsted acid catalyst is reported. This is the first known example of chiral Br?nsted acid-catalyzed asymmetric reductive amination using
- Skrypai, Vladislav,Varjosaari, Sami E.,Azam, Fawwaz,Gilbert, Thomas M.,Adler, Marc J.
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p. 5021 - 5026
(2019/05/10)
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- A silica-supported titanium catalyst for heterogeneous hydroamination and multicomponent coupling reactions
-
Highly dehydrated silica gel, SiO2700, gave a material with a total surface hydroxyl density of 0.31 ± 0.05 mmol g-1, 0.9 ± 0.1 Si-OH sites per nm2. Treatment of this material with Ti(NMe2)4/sub
- Aldrich, Kelly E.,Odom, Aaron L.
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p. 11352 - 11360
(2019/08/07)
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- B(C6F5)3-catalyzed transfer hydrogenations of imines with Hantzsch esters
-
Highly efficient transfer hydrogenations of imines were realized with as low as 0.1 mol% of B(C6F5)3 by using Hantzsch esters as a hydrogen source, furnishing a variety of amines in 80-99% yields. For the asymmetric transf
- Wang, Qiaotian,Chen, Jingjing,Feng, Xiangqing,Du, Haifeng
-
supporting information
p. 1448 - 1451
(2018/03/08)
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- Cyclometalated Half-Sandwich Iridium Complex for Catalytic Hydrogenation of Imines and Quinolines
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Several C,N-chelate cyclometalated half-sandwich iridium-based catalysts for imines and quinoline derivatives reduction have been prepared through metal-mediated C-H bond activation based on benzothiazole ligands. These iridium complexes exhibited high catalytic activity for hydrogenation of various types of imines with high yields. The most active catalyst was obtained from methoxyl substituted complex 2, showing the catalytic TOF value of 975 h-1 for the reduction of imine 6a. Additionally, these half-sandwich complexes also showed high efficiency for the catalytic hydrogenation of N-heterocyclic quinoline derivatives. Good catalytic activity was displayed for various kinds of substrates with either electron-donating or electron-withdrawing groups. Complexes 1-5 were fully characterized by NMR, IR, and elemental analysis. Molecular structures of complexes 1 and 4 were further confirmed by X-ray diffraction analysis.
- Yao, Zi-Jian,Lin, Nan,Qiao, Xin-Chao,Zhu, Jing-Wei,Deng, Wei
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p. 3883 - 3892
(2018/11/24)
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- BArF3-Catalyzed Imine Hydroboration with Pinacolborane Not Requiring the Assistance of an Additional Lewis Base
-
The rarely used boron Lewis acid tris[3,5-bis(trifluoromethyl)phenyl]borane (BArF3) is found to be an excellent catalyst for metal-free hydroboration of imines. In the presence of 1.0 mol % of BArF3, several ketimines and aldimines undergo hydroboration with pinacolborane (HBpin) at room temperature without the aid of an external Lewis base. BArF3 is more reactive than other Lewis acidic boranes, including the often-used tris(pentafluorophenyl)borane (B(C6F5)3). The steric hindrance imparted by the six fluorine atoms ortho to the boron center in B(C6F5)3 accounts for this. Mechanistic control experiments indicate conventional Lewis acid catalysis involving imine activation and hydride transfer from HBpin.
- Yin, Qin,Soltani, Yashar,Melen, Rebecca L.,Oestreich, Martin
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supporting information
p. 2381 - 2384
(2017/07/17)
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- Hydrogenation and Transfer Hydrogenation Promoted by Tethered Ru?S Complexes: From Cooperative Dihydrogen Activation to Hydride Abstraction/Proton Release from Dihydrogen Surrogates
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Hydrogenation and transfer hydrogenation of imines with cyclohexa-1,4-dienes, as well as with a representative Hantzsch ester dihydrogen surrogate, are reported. Both processes are catalyzed by tethered Ru?S complexes but differ in the activation mode of the dihydrogen source: cooperative activation of the H?H bond at the Ru?S bond leads to the corresponding Ru?H complex and protonation of the sulfur atom, whereas the same cationic Ru?S catalyst abstracts a hydride from a donor-substituted cyclohexa-1,4-diene to form the neutral Ru?H complex and a low-energy Wheland intermediate. A sequence of proton and hydride transfers on the imine substrate then yields an amine. The reaction pathways are analyzed computationally, and the established mechanistic pictures are in agreement with the experimental observations.
- Lefranc, Alice,Qu, Zheng-Wang,Grimme, Stefan,Oestreich, Martin
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supporting information
p. 10009 - 10016
(2016/07/19)
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- Efficient hydrosilylation of imines using catalysts based on iridium(iii) metallacycles
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Ir(iii) metallacycles were applied as catalysts for the hydrosilylation of various ketimines and aldimines with sodium tetrakis[(3,5-trifluoromethyl)phenyl]borate, NaBArF24, as an additive. By using a slight excess of the organosilane reagent, the reactions proceeded rapidly and efficiently, at low catalyst loadings and at room temperature. Several examples of cationic Ir(iii) catalysts could be synthesised, characterized and tested. In situ-generated catalysts proved to be more active as compared to isolated ones and species with non-coordinating BArF24 counterion gave the highest catalytic activities.
- Corre,Iali,Hamdaoui,Trivelli,Djukic,Agbossou-Niedercorn,Michon
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p. 1452 - 1458
(2015/04/14)
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- First efficient two-step/one-pot zirconium (IV)isopropoxide-mediated reductive amination of carbonyl compounds
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An efficient method for the synthesis of various primary and secondary amines through a zirconium(IV) isopropoxide-mediated reductive amination reaction of aldehydes and ketones is reported. A series of different aldehydes, ketones and amines were used leading to the expected amino products in moderate to excellent yields. The mechanistic rationale of this reaction has been postulated through the formation of a transient imine species and a diastereoselective version using (R)-phenylethylamine as chiral inducer led to the expected products in moderate to excellent yields and with diastereoselectivities up to 100%.
- Pieri, Cyril,Brunel, Jean Michel
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p. 448 - 456
(2015/06/22)
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- Zirconium complexes stabilized by amine-bridged bis(phenolato) ligands as precatalysts for intermolecular hydroamination reactions
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A series of zirconium complexes bearing amine-bridged bis(phenolato) ligands of different steric and electronic properties have been synthesized, and their activities in catalyzing intermolecular hydroamination reactions have been studied and compared. In
- Sun, Qiu,Wang, Yaorong,Yuan, Dan,Yao, Yingming,Shen, Qi
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p. 20352 - 20360
(2015/12/04)
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- B(C6F5)3-catalyzed transfer hydrogenation of imines and related heteroarenes using cyclohexa-1,4-dienes as a dihydrogen source
-
The strong boron Lewis acid tris(pentafluorophenyl) borane, B(C6F5)3, is shown to abstract a hydride from suitably donor-substituted cyclohexa-1,4-dienes, eventually releasing dihydrogen. This process is coupled with the FLPtype (FLP = frustrated Lewis pair) hydrogenation of imines and nitrogen-containing heteroarenes that are catalyzed by the same Lewis acid. The net reaction is a B(C 6F5)3-catalyzed, i.e., transition-metal-free, transfer hydrogenation using easy-toaccess cyclohexa-1,4-dienes as reducing agents. Competing reaction pathways with or without the involvement of free dihydrogen are discussed.
- Chatterjee, Indranil,Oestreich, Martin
-
supporting information
p. 1965 - 1968
(2015/02/19)
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- Titanium promoted reduction of imines with Grignards, silanes, and zinc: Identification of a new mechanism with silanes
-
Aldimines react with reducing agents, such as Grignards, phenylsilane or zinc in the presence of titanium(IV) isopropoxide to form amines and reductively coupled imines (diamines). Using deuterium labeled reagents, the mechanism of reduction to form amine
- Kumar, Akshai,Pandiakumar, Arun Kumar,Samuelson
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p. 3185 - 3190
(2014/05/06)
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- Synthesis of group 4 metal complexes stabilized by an amine-bridged bis(phenolato) ligand and their catalytic behavior in intermolecular hydroamination reactions
-
Zirconium and titanium complexes 1 and 2, bearing an amine-bridged bis(phenolato) ligand, have been synthesized and characterized. Although 1 and 2 were inactive in catalyzing intermolecular hydroamination reactions, cationic complexes generated in situ f
- Sun, Qiu,Wang, Yaorong,Yuan, Dan,Yao, Yingming,Shen, Qi
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p. 994 - 1001
(2014/03/21)
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- L-Pipecolinic acid derived Lewis base organocatalyst for asymmetric reduction of N-aryl imines by trichlorosilane: Effects of the side amide group on catalytic performances
-
A series of N-formamides derived from pipecolinic acid have been synthesized and tested as Lewis base catalysts for the enantioselective reduction of N-aryl imines by trichlorosilane. Through the investigation of the structure-efficacy relationship between the side amide group and catalytic performance, several highly effective catalysts were discovered. In particular, arylamido-type catalyst 5i and non-arylamido-type catalyst 6c exhibited high reactivity and enantioselectivity, furnishing the reduction of a wide variety of N-aryl imines with high isolated yields (up to 98%) and ee values (up to 96%) under mild conditions. Moreover, these two catalysts complement each other in terms of their tolerances to nonaromatic ketimines and non-methyl ketimines. The Royal Society of Chemistry 2013.
- Wang, Zhouyu,Wang, Chao,Zhou, Li,Sun, Jian
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p. 787 - 797
(2013/02/25)
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- N-Alkylation of amines with alcohols over nanosized zeolite beta
-
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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- Synchronizing steric and electronic effects in {RuII(NNNN,P)} complexes: The catalytic dehydrative alkylation of anilines by using alcohols as a case study
-
A series of new hexacoordinated {RuII(NNNN,P)} complexes was prepared from [RuCl2(R3P)3]. Their structure was determined by X-ray crystallography. The catalytic potential of this new class of complexes was tested in the alkylation of aniline with benzyl alcohol. In this test reaction, the influence of the counteranion plus electronic influences at the tetradentate ligand and the phosphine ligand were examined. The electrochemistry of all complexes was studied by cyclic voltammetry. Depending on the substituent at the ligand backbone, the complexes showed a different behavior. For all N-benzyl substituted complexes, reversible Ru II/III redox potentials were observed, whereas the N-methyl substituted complex possessed an irreversible oxidation event at small scan rates. Furthermore, the electronic influence of different substituents at the ligand scaffold and at the phosphine on the RuII/III redox potential was investigated. The measured E0 values were correlated to the theoretically determined HOMO energies of the complexes. In addition, these HOMO energies correlated well with the reactivity of the single complexes in the alkylation of aniline with benzyl alcohol. The exact balance of redox potential and reactivity appears to be crucial for synchronizing the multiple hydrogen-transfer events. The optimized catalyst structure was applied in a screening on scope and limitation in the catalytic dehydrative alkylation of anilines by using alcohols.
- Weickmann, Daniel,Frey, Wolfgang,Plietker, Bernd
-
supporting information
p. 2741 - 2748
(2013/03/14)
-
- Thieme chemistry journal awardees - Where are they now? Asymmetric br?nsted acid catalyzed transfer hydrogenations
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Asymmetric hydrogenations are of great importance in the synthesis of optically active amines. This account highlights the development of the first metal-free transfer hydrogenation that is both highly enantioselective and inspired by natures dehydrogen?ase. Further focus is given to the extension of this bioinspired process to provide a variety of valuable, biologically active products and natural products under mild reaction conditions. Georg Thieme Verlag Stuttgart - New York.
- Rueping, Magnus,Sugiono, Erli,Schoepke, Fenja R.
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scheme or table
p. 852 - 865
(2010/07/06)
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- Catalytic reactions of titanium alkoxides with Grignard reagents and imines: A mechanistic study
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The reactivity of Grignard reagents towards imines in the presence of catalytic and stoichiometric amounts of titanium alkoxides is reported. Alkylation, reduction, and coupling of imines take place. Whereas reductive coupling is the major reaction in sto
- Kumar, Akshai,Samuelson, Ashoka G.
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experimental part
p. 1830 - 1837
(2011/04/25)
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- Triazole-Au(I) complexes: A new class of catalysts with improved thermal stability and reactivity for intermolecular alkyne hydroamination
-
(Chemical Equation Presented) A series of 1,2,3-triazole-bound cationic Au(I) catalysts have been synthesized, and their structures have been characterized by X-ray crystallography. Variable-temperature NMR studies revealed dynamic triazole-Au cation coor
- Duan, Haifeng,Sengupta, Sujata,Petersen, Jeffrey L.,Akhmedov, Novruz G.,Shi, Xiaodong
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supporting information; experimental part
p. 12100 - 12102
(2009/12/30)
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- Enantioselective radical addition reactions to imines using binaphthol-derived chiral N-triflyl phosphoramides
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Binaphthol-derived chiral phosphoric acid catalysts were applied to enantioselective radical addition reactions of imines and provided chiral amines with good enantioselectivities (73-84% ee). Furthermore, the enantioselectivities were not affected by eit
- Lee, Sunggi,Kim, Sunggak
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experimental part
p. 3345 - 3348
(2009/09/05)
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- Chiral organic catalysts for the stereoselective reduction of carbon-nitrogen double bonds for the preparation of enantiomerically enriched amines
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The invention relates to compounds of general formula (I): wherein R1-R7 are as defined in the description for use as catalysts in the stereoselective reduction of imines in the presence of trichlorosilane as reducing agent.
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Page/Page column 9; 11
(2009/06/27)
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- Cerium(IV)-promoted ethylation of Schiff bases by triethylaluminum
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Schiff bases Ar1CH=NAr2 that are refractory towards Et3Al are activated at room temperature by cerium(IV) compounds. The ethylation takes place selectively at the methine moiety of the imine. The process is strongly influe
- Tsvelikhovsky, Dmitry,Schumann, Herbert,Blum, Jochanan
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p. 1819 - 1822
(2007/10/03)
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- Novel domino elimination-rearrangement-addition reaction of N-alkoxy(arylmethyl)amines to N-alkyl arylamines
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A new domino reaction of N-alkoxy(arylmethyl)amines to N-alkyl arylamines, consisting of three types of reactions: elimination of alcohol, rearrangement of the aryl group, and addition of an organolithium or a magnesium reagent, has been developed for the first time. Georg Thieme Verlag Stuttgart.
- Miyata, Okiko,Ishikawa, Tatsuya,Ueda, Masafumi,Naito, Takeaki
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p. 2219 - 2222
(2007/10/03)
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- Reactive ketimino radical acceptors: Intermolecular alkyl radical addition to imines with a phenolic hydroxyl group
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Intermolecular carbon radical addition to the carbon-nitrogen double bond of ketimines was studied. In the study on the reactivity of various aldimines, we found that the aldimine 7 having a phenolic hydroxyl group shows an excellent reactivity toward nuc
- Miyabe, Hideto,Yamaoka, Yousuke,Takemoto, Yoshiji
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p. 2099 - 2106
(2007/10/03)
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- Highly efficient alkylation to ketones and aldimines with Grignard reagents catalyzed by zinc(II) chloride
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A highly efficient alkylation to ketones and aldimines with Grignard reagents in the presence of catalytic trialkylzinc(II) ate complexes derived from ZnCl2 (10 mol %) in situ was developed. This simple Zn(II)-catalyzed alkylation could minimize the well-known but serious problems with the use of only Grignard reagents, which leads to reduction and aldol side products, and the yield of desired alkylation products could be improved. Copyright
- Hatano, Manabu,Suzuki, Shinji,Ishihara, Kazuaki
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p. 9998 - 9999
(2007/10/03)
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- Direct and indirect reductive amination of aldehydes and ketones with solid acid-activated sodium borohydride under solvent-free conditions
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A simple and convenient procedure for reductive amination of aldehydes and ketones using sodium borohydride activated by boric acid, p-toluenesulfonic acid monohydrate or benzoic acid as reducing agent under solvent-free conditions is described.
- Byung, Tae Cho,Sang, Kyu Kang
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p. 5725 - 5734
(2007/10/03)
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- The chemistry of alkylstrontium halide analogues: Barbier-type alkylation of imines with alkyl halides
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The chemistry of alkylstrontium halide analogues was examined. In the presence of metallic strontium, the Barbier-type alkylation of imines with alkyl iodides proceeded smoothly at room temperature under an argon atmosphere to afford the corresponding alk
- Miyoshi, Norikazu,Ikehara, Daitetsu,Kohno, Tadashi,Matsui, Aki,Wada, Makoto
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p. 760 - 761
(2007/10/03)
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- Addition of trialkylalanes to imines under zirconium catalysis
-
Trialkylalanes, which are inert toward imines, undergo addition to them in the presence of a catalytic amount of dichlorodicyclopentadienylzirconium(IV) (Cp2ZrCl2). The reaction tolerates the presence of several functional groups in the starting imine such as halo, amide, nitrile, and hydroxy groups. A possible reaction pathway is proposed involving metallacyclic intermediates. Georg Thieme Verlag Stuttgart.
- Denhez, Clement,Vasse, Jean-Luc,Szymoniak, Jan
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p. 2075 - 2079
(2007/10/03)
-
- RUTHENIUM-CATALYZED HYDROAMINATION OF OLEFINS
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Applicants have unexpectedly discovered that catalysts made from a ruthenium catalyst precursor or preformed ruthenium catalysts as otherwise described in the present specification are capable of effecting the addition of a N-H bond across an olefin C=C (olefinic) bond of a substrate with a high degree of regioselectivity and enantioselectivity in high yield. These addition reactions proceed in an anti-Markovnikov or Markovnikov fashion depending upon the catalyst precursor used to generate the ruthenium catalyst which actually participates in the addition reaction. The present invention relates to methods of adding N-H bonds across an olefinic bond in a substrate, using a ruthenium catalyst precursor or catalyst I comprising a compound according to the general structure I: Formula (I) where Ru is a ruthenium atom; L1 represents one or more coordinated ancillary ligands, which may be all the same ligand or which may be a combination of different ligands, each of which may be neutral or formally charged, and each of which may be monodentate and coordinated to ruthenium through a single atom or which may be linked or chelated and bound through more than one atom; L2 represents one or more formally charged ligands which are the same or different and which are optionally susceptible to removal with a strong acid; and x is 0-6, preferably 1, y is 0-6, preferably 2 and n is 1-4, preferably 1.
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-
-
- Br?nsted acid catalysis: Organocatalytic hydrogenation of imines
-
A new Br?nsted acid catalysed hydrogenation of imines with Hantzsch dihydropyridine as the hydrogen source has been developed. Diphenyl phosphate (DPP) and various other acids catalyse this first metal-free hydrogen transfer to give various amines under m
- Rueping, Magnus,Azap, Cengiz,Sugiono, Erli,Theissmann, Thomas
-
p. 2367 - 2369
(2007/10/03)
-
- Lanthanide-promoted ethylation of schiff bases by triethylaluminum
-
Equation presented. Schiff bases of aromatic aldehydes and anilines that fail to react with triethylaluminum are smoothly alkylated at room temperature in the presence of lanthanide catalysts. The alkylation takes place selectively at the vinylic carbon a
- Tsvelikhovsky, Dmitry,Gelman, Dmitri,Molander, Gary A.,Blum, Jochanan
-
p. 1995 - 1997
(2007/10/03)
-
- Ruthenium-catalyzed transfer hydrogenation of imines by propan-2-ol in benzene
-
Transfer hydrogenation of a variety of different imines to the corresponding amines by propan-2-ol in benzene catalyzed by [Ru2(CO)4(μ H)(C4Ph4COHOCC4Ph4)] (1) has been studied. The reaction is highly efficient with turnover frequencies of over 800 per hour, and the product amines were obtained in excellent yields. A remarkable concentration dependence of propan-2-ol was observed when the reaction was run in benzene as cosolvent. An optimum was obtained at 24 equivalents of propan-2-ol to imine, and further increase of the propan-2-ol led to a dramatic decrease in rate. Also the use of polar cosolvents with 24 equivalents of propan-2-ol gave a low rate. It was found that ketimines react faster than aldimines and that electron-donating substituents on the imine increase the rate of the catalytic transfer hydrogenation. Electron-withdrawing substituents decreased the rate. An isomerization was observed with imines having an α-hydrogen at the N-alkyl substituent, which is in accordance with a mechanism involving a ruthenium-amine intermediate. It was demonstrated that the ruthenium-amine complex from α-methylbenzylamine, corresponding to the postulated intermediate, can replace 1 as catalyst in the transfer hydrogenation of imines. A primary deuterium isotope effect of kCH/CD = 2.7 ± 0.25 was observed when 2-deuterio-propan-2-ol vas used in place of propan-2-ol in the ransfer hydrogenation of N-phenyl-(1-phenylethylidene)amine.
- Samec, Joseph S. M.,Baeckvall, Jan-E.
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p. 2955 - 2961
(2007/10/03)
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- Zirconium-catalyzed ethylmagnesiation of imines - Scope and mechanism
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The title reaction has been developed for a series of aldimines and ketimines. Most notably, ketimines - which are totally inert towards alkyl Grignard reagents in the absence of the zirconium catalyst - react smoothly when 10 mol % of Cp2ZrCl2 is added. The mechanism of the reaction has been studied. The intermediate azazirconacycle proved to react by two competing pathways involving mono- and dimagnesiated final products before hydrolysis.
- Gandon, Vincent,Bertus, Philippe,Szymoniak, Jan
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p. 3677 - 3681
(2007/10/03)
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- Addition of diethylzinc to imines promoted by Lewis acid
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The alkylation of imines by using diethylzinc reagent in the presence of Lewis acid afforded secondary amines in high yield.
- Hou, Xue Long,Zheng, Xiao Lan,Dai, Li Xin
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p. 6949 - 6952
(2007/10/03)
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- Reductions of C=O and C=N groups with the systems composed of (η5-C5H5)2MoH2 and acids
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Selective reductions of organic compounds, such as carbonyl compounds and imines, using a system composed of Cp2MoH2 and acids are examined. This system can reduce the substrates under mild conditions. Extremely high diastereoselectivity was achieved in the reduction of 4-t-butylcyclohexanone. The reactivity of imines depends on their structure. Aromatic imines are found to be more reactive than aliphatic imines.
- Minato, Makoto,Fujiwara, Yutaka,Koga, Miho,Matsumoto, Naoya,Kurishima, Susumu,Natori, Makoto,Sekizuka, Norihiro,Yoshioka, Ken-Ichiro,Ito, Takashi
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p. 139 - 145
(2007/10/03)
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- Arene-catalysed lithiation of triflates and triflamides under Barbier-type conditions: An indirect transformation of alcohols and amines into organolithium compounds
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The reaction of alkyl triflates 1 or benzyl triflamides 3 with an excess of lithium powder and a catalytic amount of naphthalene (4 mol%) in the presence of different electrophiles [Me3SiCl, Pr(i)CHO, Bu(t)CHO, PhCHO, 4-MeOC6H4-CHO, CH3(CH2)6CHO, Et2CO, (CH2)5CO, (c-C3H5)2CO, PhCOMe, 4-MeC6H4COPh, PhCh=NPh, n-C8H7CON(CH2)4] in THF at temperature ranging between -78 and 0°C leads, after hydrolysis with water, to the corresponding condensation products 2. When α,β-unsaturated carbonyl compounds are used as electrophilic compounds 1,2- (3-cyclohexenone) or 1,4-addition (cinnamaldehyde or benzylideneacetone) takes place depending on the electrophile used.
- Alonso, Emma,Ramon, Diego J.,Yus, Miguel
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p. 14341 - 14348
(2007/10/03)
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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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p. 647 - 648
(2007/10/02)
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- Alkylation of Benzothiazolines and the Stevens Rearrangement of the Resulting 2,3,3-Trisubstituted Benzothiazolinium Salts
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Alkylation of 2-substituted 3-methyl- or 3-ethylbenzothiazolines with Meerwein reagents gave 2-substituted 3,3-dialkylbenzothiazolinium tetrafluoroborates (3).The configuration of two alkyl groups on the nitrogen was assigned by NMR spectra and NOE measurement.In the Stevens rearrangement of 3 with lithium diisopropylamide ethyl group showed a much larger migratory aptitude (Et:Me>20:1) than methyl group irrespective of the configuration of 3, and cyclic ammonium ylide with planar ?-type carbanion was proposed as an intermediate. 3 suffered nucleophilic attack at the ring sulfur atom by butyllithium to afford a ring-opened ammonium ylide, which collapses to a radical pair to give unusual Stevens rearrangement product, where o-alkylthiophenyl group migrated selectively in preference to alkyl group, because of stabilization by participation of o-alkylthio group.
- Akiba, Kin-ya,Ohara, Yoshio,Inamoto, Naoki
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p. 2976 - 2983
(2007/10/02)
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