- Switching Selectivity in Copper-Catalyzed Transfer Hydrogenation of Nitriles to Primary Amine-Boranes and Secondary Amines under Mild Conditions
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A simple and efficient copper-catalyzed selective transfer hydrogenation of nitriles to primary amine-boranes and secondary amines with an oxazaborolidine-BH3 complex is reported. The selectivity control was achieved under mild conditions by switching the solvent and the copper catalysts. More than 30 primary amine-boranes and 40 secondary amines were synthesized via this strategy in high selectivity and yields of up to 95%. The strategy was applied to the synthesis of 15N labeled in 89% yield.
- Song, Hao,Xiao, Yao,Zhang, Zhuohua,Xiong, Wanjin,Wang, Ren,Guo, Liangcheng,Zhou, Taigang
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p. 790 - 800
(2022/01/11)
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- Nickel Complexes Bearing N,N,O-Tridentate Salicylaldiminato Ligand: Efficient Catalysts for Imines Formation via Dehydrogenative Coupling of Primary Alcohols with Amines
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Treatment of salicylaldiminato ligand L1H-L2H (L1H = 2,4-di-tert-butyl-6-((quinolin-8-ylimino)methyl)phenol; L2H = 2,4-di-tert-butyl-6-(((2-(diethylamino)ethyl)imino)methyl)phenol) with Ni(OAc)2·4H2O in refluxing ethanol afforded nickel complexes [(L1)Ni(OAc)] (1) and [(L2)Ni(OAc)] (2), respectively. Reaction of L3H (L3H = (2,4-di-tert-butyl-6-(((2-(pyridin-2-yl)ethyl)imino)methyl)phenol)) with Ni(OAc)2·4H2O in the presence of excess triethylanmine gave the dual ligands coordinated nickel complex [(L2)2Ni] (3). Complexes 1-3 were well characterized by high-resolution mass spectrometry, infrared spectroscopy, elemental analysis, and X-ray diffraction analysis. All the three Ni(II) complexes exhibited efficient activity and good selectivity in the acceptorless dehydrogenative coupling of alcohols and amines to produce imines and diimines. The present protocol provides an atom-economical and sustainable route for the synthesis of various imine derivatives by employing an earth-abundant nickel salt and easily prepared salicylaldiminato ligands.
- Han, Zhangang,Hao, Zhiqiang,Lin, Jin,Lu, Guo-Liang,Zhang, Junhua,Zhang, Xiaoying
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p. 3843 - 3853
(2021/11/18)
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- Electrochemical, Iodine-Mediated α-CH Amination of Ketones by Umpolung of Silyl Enol Ethers
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The electrochemical, oxidative Umpolung reaction of silyl enol ethers utilizing simple iodide salts for the synthesis of α-amino ketones is described. The products were isolated in excellent yields of up to 100percent, and various functionalized starting materials were accepted in an undivided electrochemical cell design. Moreover, a sensitivity assessment to ensure an improved reproducibility of the reaction and cyclic voltammetry experiments were performed to postulate a plausible reaction mechanism on their basis.
- Strehl, Julia,Hilt, Gerhard
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supporting information
p. 5968 - 5972
(2020/08/12)
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- Reconfigurable system for automated optimization of diverse chemical reactions
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Chemical synthesis generally requires labor-intensive, sometimes tedious trial-and-error optimization of reaction conditions. Here, we describe a plug-and-play, continuous-flow chemical synthesis system that mitigates this challenge with an integrated combination of hardware, software, and analytics. The system software controls the user-selected reagents and unit operations (reactors and separators), processes reaction analytics (high-performance liquid chromatography, mass spectrometry, vibrational spectroscopy), and conducts automated optimizations. The capabilities of this system are demonstrated in high-yielding implementations of C-C and C-N cross-coupling, olefination, reductive amination, nucleophilic aromatic substitution (SNAr), photoredox catalysis, and a multistep sequence. The graphical user interface enables users to initiate optimizations, monitor progress remotely, and analyze results. Subsequent users of an optimized procedure need only download an electronic file, comparable to a smartphone application, to implement the protocol on their own apparatus.
- Bédard, Anne-Catherine,Adamo, Andrea,Aroh, Kosi C.,Russell, M. Grace,Bedermann, Aaron A.,Torosian, Jeremy,Yue, Brian,Jensen, Klavs F.,Jamison, Timothy F.
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p. 1220 - 1225
(2018/10/04)
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- Efficient and Selective Hydrosilylation of Secondary and Tertiary Amides Catalyzed by an Iridium(III) Metallacycle: Development and Mechanistic Investigation
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Readily accessible cationic IrIII metallacycles catalyze efficiently the chemoselective hydrosilylation of tertiary and secondary amides to amines. The catalyst described herein operates at low loadings using inexpensive 1,1,3,3-tetramethyldisiloxane and allows fast reactions with high yields, selectivities, and turnover numbers. A transient iminium intermediate has been observed for the first time by using mass spectrometry, and the activation of the catalyst and the silane reagent have been studied by using DFT calculations. These fundamental insights support the present and future improvements of IrIII metallacycles through proper ligand modifications and enable further broad applications of catalysts based on metallacycles.
- Corre, Yann,Trivelli, Xavier,Capet, Frédéric,Djukic, Jean-Pierre,Agbossou-Niedercorn, Francine,Michon, Christophe
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p. 2009 - 2017
(2017/06/13)
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- Synthesis of α-amino acids through samarium(II) iodide promoted reductive coupling of nitrones with CO2
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Several N-benzylnitrones reacted with carbon dioxide in the presence of samarium(II) iodide leading to α-amino acids as the products of reductive C-C coupling. The best selectivities were observed at a carbon dioxide pressure of 50 bar at ambient temperature. The influences of different functional groups in the nitrone backbone and of the coordinating additives to samarium(II) iodide on the product distribution were investigated. The racemic α-amino acids were obtained in up to 70% yield based on HPLC data. A novel approach to the synthesis ofα-amino acids is disclosed, involvingC-carboxylation of nitrones by gaseous CO2 under reductive coupling reaction conditions (SmI2, 0.1 M in THF) at ambient temperature and 50 bar of CO 2 pressure. Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.
- Prikhod'Ko, Alexander,Walter, Olaf,Zevaco, Thomas A.,Garcia-Rodriguez, Jaime,Mouhtady, Omar,Py, Sandrine
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supporting information; experimental part
p. 3742 - 3746
(2012/09/25)
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- Ruthenium-catalyzed nitro and nitrile compounds coupling with alcohols: Alternative route for N-substituted amine synthesis
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The one-pot synthesis of N-substituted secondary amines from nitrobenzenes and benzonitriles has been developed (see scheme). This report presents a versatile and simple method for the synthesis of N-substituted amines in excellent yield and high efficiency from nitro and nitrile compounds with alcohols.
- Cui, Xinjiang,Zhang, Yan,Shi, Feng,Deng, Youquan
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supporting information; experimental part
p. 2587 - 2591
(2011/04/12)
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- Selective synthesis of secondary amines via N-alkylation of primary amines and ammonia with alcohols by supported copper hydroxide catalysts
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The N-alkylation of primary amines and ammonia (in situ generated from urea or aqueous ammonia) with alcohols to secondary amines was efficiently promoted by supported copper hydroxide catalysts, Cu(OH)xAl2O 3 and Cu(OH)x/TiO2. The observed catalysis was truly heterogeneous, and the catalysts could be reused without an appreciable loss of catalytic performance.
- He, Jinling,Yamaguchi, Kazuya,Mizuno, Noritaka
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supporting information; experimental part
p. 1182 - 1183
(2011/02/28)
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- Effective reductive amination of carbonyl compounds with hydrogen catalyzed by iridium complex in organic solvent and in ionic liquid
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The direct reductive amination (DRA) of carbonyl compounds with amines has been achieved using homogenous iridium catalyst and gaseous hydrogen. It appeared that the cationic iridium catalyst, [Ir(cod)2]BF 4, without any other ligands was sufficient for the reaction. For the DRA of the ketone substrates, an ionic liquid, [Bmim]BF4, was found to be superior to the other organic solvent used. Especially, the counter anion of the ionic liquid has a significant influence on the selectivity, and at the same time, a high reaction temperature was found to be crucial for the excellent selectivity.
- Imao, Daisuke,Fujihara, Shoichiro,Yamamoto, Takeshi,Ohta, Tetsuo,Ito, Yoshihiko
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p. 6988 - 6992
(2007/10/03)
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