共查询到20条相似文献,搜索用时 156 毫秒
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Jenny Wettergren Dr. Elina Buitrago Per Ryberg Dr. Hans Adolfsson Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(23):5709-5718
Lithium‐powered : A kinetic investigation into the asymmetric transfer hydrogenation of non‐activated aryl alkyl ketones, catalyzed by N‐Boc‐protected α‐amino acid hydroxyamide ruthenium–arene complexes, has revealed that the reactions proceed through an unprecedented bimetallic outer‐sphere mechanism. Under optimized conditions, these catalysts provide access to secondary alcohols in high yields and with excellent enantioselectivities (>99 % ee).
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Transfer Hydrogenation of Ketones Catalyzed by Surface‐Active Ruthenium and Rhodium Complexes in Water 下载免费PDF全文
Dr. Alexander M. Kalsin Dr. Tat'yana A. Peganova Dr. Valentin V. Novikov Alexandra I. Zhamoytina Dr. Luca Gonsalvi Dr. Maurizio Peruzzini 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(3):846-854
An improved, high‐yield, one‐pot synthetic procedure for water‐soluble ligands functionalized with trialkyl ammonium side groups H2N(CH2)2NHSO2‐p‐C6H4CH2[NMe2(CnH2n+1)]+ ( [HL n ]+ ; n=8, 16) was developed. The corresponding new surface‐active complexes [(p‐cymene)RuCl( L n )] and [Cp*RhCl( L n )] (Cp*=η5‐C5Me5) were prepared and characterized. For n=16 micelles are formed in water at concentrations as low as 0.6 mM , as demonstrated by surface‐tension measurements. The complexes were used for catalytic transfer hydrogenation of ketones with formate in water. Highly active catalyst systems were obtained in the case of complexes bearing C16 tails due to their ability to be adsorbed at the water/substrate interface. The scope of these catalyst systems in aqueous solutions was extended from partially water soluble aryl alkyl ketones (acetophenone, butyrophenone) to hydrophobic dialkyl ketones (2‐dodecanone). 相似文献
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Fan Jiang Kedong Yuan Dr. Mathieu Achard Dr. Christian Bruneau 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(31):10343-10352
Various ruthenium(II) complexes that contain phosphinesulfonate chelate have been synthesized. Arene‐free complexes were found to be efficient in the base‐free hydrogenation of various aryl ketones, whereas the arene‐containing precatalysts required the presence of an amine as an additive. The seminal asymmetric hydrogenation reaction by using the new Sulfo‐Binepine ligand was also investigated for the possible intervention of a dihydride species. 相似文献
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Philipp Melle Jan Thiede Daniela A. Hey Prof. Dr. Martin Albrecht 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(58):13226-13234
The rational optimization of homogeneous catalysts requires ligand platforms that are easily tailored to improve catalytic performance. Here, it is demonstrated that pyridylidene amides (PYAs) provide such a platform to custom-shape transfer hydrogenation catalysts with exceptional activity. Specifically, a series of meta-PYA pincer ligands with differently substituted PYA units has been synthezised and coordinated to ruthenium(II) centres to form bench-stable tris-acetonitrile complexes [Ru(R-PYA-pincer)(MeCN)3](PF6)2 (R=OMe, Me, H, Cl, CF3). Analytic studies including 1H NMR spectroscopy, cyclic voltammetry, and X-ray crystallography reveal a direct influence of the substituents on the electronic properties of the ruthenium center. The complexes are active in the catalytic transfer hydrogenation of ketones, with activities directly encoded by the PYA substitution pattern. Their perfomance improves further upon exchange of an ancillary MeCN ligand with PPh3. While complexes [Ru(R-PYA-pincer)(PPh3)(MeCN)2](PF6)2 were only isolated for R=H, Me, an in situ protocol was developed to generate these complexes in situ for R=OMe, Cl, CF3 by using a 1:2 ratio of the complexes and PPh3. This in situ protocol together with a short catalyst pre-activation provided highly active catalytic systems. The most active pre-catalyst featured the methoxy-substituted PYA ligand and reached turnover frenquencies of 210 000 h−1 under an exceptionally low catalyst loading of 25 ppm for the benchmark substrate benzophenone, representing one of the most active transfer hydrogenation systems known to date. 相似文献
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Dr. Xu Quan Dr. Sutthichat Kerdphon Bram B. C. Peters Dr. Janjira Rujirawanich Dr. Suppachai Krajangsri Dr. Jira Jongcharoenkamol Prof. Pher G. Andersson 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(58):13311-13316
Novel bidentate N-heterocyclic carbene-phosphine iridium complexes have been synthesized and evaluated in the hydrogenation of ketones. Reported catalytic systems require base additives and, if excluded, need elevated temperature or high pressure of hydrogen gas to achieve satisfactory reactivity. The developed catalysts showed extremely high reactivity and good enantioselectivity under base-free and mild conditions. In the presence of 1 mol % catalyst under 1 bar hydrogen pressure at room temperature, hydrogenation was complete in 30 minutes giving up to 96 % ee. Again, this high reactivity was achieved in additive-free conditions. Mechanistic experiments demonstrated that balloon pressure of hydrogen was sufficient to form the activate species by reducing and eliminating the 1,5-cyclooctadiene ligand. The pre-activated catalyst was able to hydrogenate acetophenone with 89 % conversion in 5 min. 相似文献
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Walter Baratta Prof. Giorgio Chelucci Dr. Santo Magnolia Dr. Katia Siega Dr. Pierluigi Rigo Prof. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(3):726-732
Chiral pincer ruthenium complexes of formula [RuCl(CNN)(Josiphos)] ( 2 – 7 ; Josiphos=1‐[1‐(dicyclohexylphosphano)ethyl]‐2‐(diarylphosphano)ferrocene) have been prepared by treating [RuCl2(PPh3)3] with (S,R)‐Josiphos diphosphanes and 1‐substituted‐1‐(6‐arylpyridin‐2‐yl)methanamines (HCNN; substituent=H ( 1 a ), Me ( 1 b ), and tBu ( 1 c )) with NEt3. By using 1 b and 1 c as a racemic mixture, complexes 4 – 7 were obtained through a diastereoselective synthesis promoted by acetic acid. These pincer complexes, which display correctly matched chiral PP and CNN ligands, are remarkably active catalysts for the asymmetric reduction of alkyl aryl ketones in basic alcohol media by both transfer hydrogenation (TH) and hydrogenation (HY), achieving enantioselectivities of up to 99 %. In 2‐propanol, the enantioselective TH of ketones was accomplished by using a catalyst loading as low as 0.002 mol % and afforded a turnover frequency (TOF) of 105–106 h?1 (60 and 82 °C). In methanol/ethanol mixtures, the CNN pincer complexes catalyzed the asymmetric HY of ketones with H2 (5 atm) at 0.01 mol % relative to the complex with a TOF of ≈104 h?1 at 40 °C. 相似文献
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合成了两个新的胺膦钌配合物trans-RuCl2(P2N2Me)和trans-RuCl2(P2N2H4Me).进行了元素分析、IR、NMR等谱学或X射线衍射分析.它们均具有六配位八面体构型.在碱性介质中,以异丙醇为溶剂,两个配合物可作为有效的催化剂实现苯乙酮的氢转移还原.讨论了催化氢化机理. 相似文献
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Nils Meyer Dr. Alan J. Lough Dr. Robert H. Morris Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(22):5605-5610
Ferrous efficiency : New achiral and chiral iron complexes containing P‐N‐N‐P diiminodiphosphine ligands display high activity—and in the case of the catalyst shown, high enantioselectivity—in the catalytic transfer hydrogenation of ketones. This is an important step in the journey to replace precious and toxic platinum metal catalysts with cheap and environmentally friendly iron compounds.
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Dr. Jian‐Bo Xie Prof. Jian‐Hua Xie Xiao‐Yan Liu Qian‐Qian Zhang Prof. Qi‐Lin Zhou 《化学:亚洲杂志》2011,6(3):899-908
The iridium complexes of chiral spiro aminophophine ligands, especially the ligand with 3,5‐di‐tert‐butylphenyl groups on the P atom ( 1c ) were demonstrated to be highly efficient catalysts for the asymmetric hydrogenation of alkyl aryl ketones. In the presence of KOtBu as a base and under mild reaction conditions, a series of chiral alcohols were synthesized in up to 97 % ee with high turnover number (TON up to 10 000) and high turnover frequency (TOF up to 3.7×104 h−1). Investigation on the structures of the iridium complexes of ligands (R)‐ 1a and 1c by X‐ray analyses disclosed that the 3,5‐di‐tert‐butyl groups on the P‐phenyl rings of the ligand are the key factor for achieving high activity and enantioselectivity of the catalyst. Study of the catalysts generated from the Ir‐(R)‐ 1c complex and H2 by means of ESI‐MS and NMR spectroscopy indicated that the early formed iridium dihydride complex with one (R)‐ 1c ligand was the active species, which was slowly transformed into an inactive iridium dihydride complex with two (R)‐ 1c ligands. A plausible mechanism for the reaction was also suggested to explain the observations of the hydrogenation reactions. 相似文献
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CHENG Zhi-bo YU Shen-luan LI Yan-yun DONG Zhen-rong SUN Guo-song HUANG Ke-lin GAO Jing-xing . State Key Laboratory of Physical Chemistry of Solid Surfaces National Engineering Laboratory for Green Chemical Productions of Alcohols-Ethers-Esters 《高等学校化学研究》2011,(2):170-173
The efficient catalytic systems generated in situ from RuCl2(PPh3)3 and chiral ligands N,N-bis[2-(di-o- tolylphosphino)-benzyl]cyclohexane-1,2-diamine(2) were employed for asymmetric transfer hydrogenation of aromatic ketones, giving the corresponding optically active alcohols with high activities(up to 99% conversion) and excellent enantioselectivities(up to 96% e.e.) under mild conditions. The chiral ruthenium(Ⅱ) complex (R,R)-3 has been prepared and characterized by NMR and X-ray crystallography. 相似文献
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Alessandro Passera Prof. Dr. Antonio Mezzetti 《Angewandte Chemie (International ed. in English)》2020,59(1):187-191
The bis(carbonyl) manganese(I) complex [Mn(CO)2( 1 )]Br ( 2 ) with a chiral (NH)2P2 macrocyclic ligand ( 1 ) catalyzes the asymmetric transfer hydrogenation of polar double bonds with 2‐propanol as the hydrogen source. Ketones (43 substrates) are reduced to alcohols in high yields (up to >99 %) and with excellent enantioselectivities (90–99 % ee). A stereochemical model based on attractive CH–π interactions is proposed. 相似文献
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Dr. Rosa Adam Dr. Elisabetta Alberico Dr. Wolfgang Baumann Dr. Hans‐Joachim Drexler Dr. Ralf Jackstell Dr. Henrik Junge Prof. Dr. Matthias Beller 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(14):4991-5002
A series of seven novel NImNHP‐type pincer imidazolylphosphine ruthenium complexes has been synthesized and fully characterized. The use of hydrogenation of benzonitrile as a benchmark test identified [RuHCl(CO)(NImNHPtBu)] as the most active catalyst. With its stable Ru?BH4 analogue, in which chloride is replaced by BH4, a broad range of (hetero)aromatic and aliphatic nitriles, including industrially interesting adiponitrile, has been hydrogenated under mild and base‐free conditions. 相似文献
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简要介绍了多齿胺膦金属配合物的设计合成。这些多齿配合显示了单齿胺或膦金属配合物所不具有的丰富结构类型和特殊催化性质,合成和表征了含有结构类似的双亚胺双膦钌配合物(R,R)-3和双胺双膦钌配合物(R,R)-4。配合物(R,R)-4可作为多种芳香酮不对称氢化的手性催化剂,其光学收率最高达97%。讨论了钌配合物的催化作用机理。 相似文献
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Christian A. Sandoval Dr. Fusheng Bie Aki Matsuoka Yoshiki Yamaguchi Dr. Hiroshi Naka Prof. Dr. Yuehui Li Koichi Kato Prof. Dr. Noriyuki Utsumi Kunihiko Tsutsumi Takeshi Ohkuma Prof. Dr. Kunihiko Murata Dr. Ryoji Noyori Prof. Dr. 《化学:亚洲杂志》2010,5(4):806-816
Aromatic ketones are enantioseletively hydrogenated in alcohols containing [RuX{(S,S)‐Tsdpen}(η6‐p‐cymene)] (Tsdpen=TsNCH(C6H5)CH(C6H5)NH2; X=TfO, Cl) as precatalysts. The corresponding Ru hydride (X=H) acts as a reducing species. The solution structures and complete spectral assignment of these complexes have been determined using 2D NMR (1H‐1H DQF‐COSY, 1H‐13C HMQC, 1H‐15N HSQC, and 1H‐19F HOESY). Depending on the nature of the solvents and conditions, the precatalysts exist as a covalently bound complex, tight ion pair of [Ru+(Tsdpen)(cymene)] and X?, solvent‐separated ion pair, or discrete free ions. Solvent effects on the NH2 chemical shifts of the Ru complexes and the hydrodynamic radius and volume of the Ru+ and TfO? ions elucidate the process of precatalyst activation for hydrogenation. Most notably, the Ru triflate possessing a high ionizability, substantiated by cyclic voltammetry, exists in alcoholic solvents largely as a solvent‐separated ion pair and/or free ions. Accordingly, its diffusion‐derived data in CD3OD reflect the independent motion of [Ru+(Tsdpen)(cymene)] and TfO?. In CDCl3, the complex largely retains the covalent structure showing similar diffusion data for the cation and anion. The Ru triflate and chloride show similar but distinct solution behavior in various solvents. Conductivity measurements and catalytic behavior demonstrate that both complexes ionize in CH3OH to generate a common [Ru+(Tsdpen)(cymene)] and X?, although the extent is significantly greater for X=TfO?. The activation of [RuX(Tsdpen)(cymene)] during catalytic hydrogenation in alcoholic solvent occurs by simple ionization to generate [Ru+(Tsdpen)(cymene)]. The catalytic activity is thus significantly influenced by the reaction conditions. 相似文献