- Transfer hydrogenation of aryl ketones with homogeneous ruthenium catalysts containing diazafluorene ligands
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Novel cationic ruthenium(II) complexes bearing a 4,5-diazafluorene unit and p-cymene as ligands have been synthesised. The complexes were characterised based on elemental analysis and Fourier transform infrared and nuclear magnetic resonance spectroscopies. The synthesised Ru(II) complexes were employed as pre-catalysts for the transfer hydrogenation of aromatic ketones using 2-propanol as both hydrogen source and solvent in the presence of NaOH. All complexes showed high catalytic activity as catalysts in the reduction of substituted acetophenones to corresponding secondary alcohols. The products of catalysis were obtained with conversion rates of between 80 and 99%. Among the seven new complexes investigated, the most efficient catalyst showed turnover frequencies in the range 255–291 h?1 corresponding to 85 to 97% conversion, respectively. Copyright
- Baran, Mehmet F?rat,Durap, Feyyaz,Aydemir, Murat,Baysal, Ak?n
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- Synthesis, structure and reactivity of Pd and Ir complexes based on new lutidine-derived NHC/phosphine mixed pincer ligands
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Coordination studies of new lutidine-derived hybrid NHC/phosphine ligands (CNP) to Pd and Ir have been performed. Treatment of the square-planar [Pd(CNP)Cl](AgCl2) complex 2a with KHMDS produces the selective deprotonation at the CH2P arm of the pincer to yield the pyridine-dearomatised complex 3a. A series of cationic [Ir(CNP)(cod)]+ complexes 4 has been prepared by reaction of the imidazolium salts 1 with Ir(acac)(cod). These derivatives exhibit in the solid state, and in solution, a distorted trigonal bipyramidal structure in which the CNP ligands adopt an unusual C(axial)-N(equatorial)-P(equatorial) coordination mode. Reactions of complexes 4 with CO and H2 yield the carbonyl species 5a(Cl) and 6a(Cl), and the dihydrido derivatives 7, respectively. Furthermore, upon reaction of complex 4b(Br) with base, selective deprotonation at the methylene CH2P arms is observed. The, thus formed, deprotonated Ir complex 8b reacts with H2 in a ligand-assisted process leading to the trihydrido complex 9b, which can also be obtained by reaction of 7b(Cl) with H2 in the presence of KOtBu. Finally, the catalytic activity of Ir-CNP complexes in the hydrogenation of ketones has been briefly assessed.
- Sánchez, Práxedes,Hernández-Juárez, Martín,álvarez, Eleuterio,Paneque, Margarita,Rendón, Nuria,Suárez, Andrés
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- Manganese-catalyzed homogeneous hydrogenation of ketones and conjugate reduction of α,β-unsaturated carboxylic acid derivatives: A chemoselective, robust, and phosphine-free in situ-protocol
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We communicate a user-friendly and glove-box-free catalytic protocol for the manganese-catalyzed hydrogenation of ketones and conjugated C[dbnd]C[sbnd]bonds of esters and nitriles. The respective catalyst is readily assembled in situ from the privileged [Mn(CO)5Br] precursor and cheap 2-picolylamine. The catalytic transformations were performed in the presence of t-BuOK whereby the corresponding hydrogenation products were obtained in good to excellent yields. The described system offers a brisk and atom-efficient access to both secondary alcohols and saturated esters avoiding the use of oxygen-sensitive and expensive phosphine-based ligands.
- Topf, Christoph,Vielhaber, Thomas
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- Postsynthetic Modification of Half-Sandwich Ruthenium Complexes by Mechanochemical Synthesis
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A mild and environmentally friendly method to synthesize half-sandwich ruthenium complexes through the Wittig reaction between an aldehyde-tagged half-sandwich ruthenium complex and phosphorus ylide mechanochemically is reported herein. The mechanochemical synthesis of valuable half-sandwich ruthenium complexes resulted in a fast reaction, good yield with simple workup, and the avoidance of harsh reaction conditions and organic solvents. The synthesized half-sandwich ruthenium complexes exhibited high catalytic activity for transfer hydrogenation of ketones using 2-propanol as the hydrogen source and solvent. Density functional theory was carried out to propose a mechanism for the transfer hydrogenation process. The modeling suggests the importance of the labile p-cymene ligand in modulating the reactivity of the catalyst.
- Jia, Wei-Guo,Zhi, Xue-Ting,Li, Xiao-Dong,Zhou, Jun-Peng,Zhong, Rui,Yu, Haibo,Lee, Richmond
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p. 4313 - 4321
(2021/05/04)
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- Pincerlike molybdenum complex and preparation method thereof, catalytic composition and application thereof, and alcohol preparation method
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The invention discloses a clamp-type molybdenum complex, a preparation method, a corresponding catalyst composition and application. The method comprises the steps: obtaining 9 molybdenum complexes with different structures through coordination reaction of 2-(substituent ethyl)-(5, 6, 7, 8-tetrahydroquinolyl) amine and a corresponding carbonyl molybdenum metal precursor; and catalyzing a ketone compound transfer hydrogenation reaction through a molybdenum complex to generate 40 alcohol compounds. The preparation method of the molybdenum complex is simple, high in yield and good in stability. For a transfer hydrogenation reaction of ketone, the molybdenum-based catalytic system has high catalytic activity and small molybdenum loading capacity, is used for production of aromatic and aliphatic alcohols, and has the advantages of simple method, small environmental pollution and high yield.
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Paragraph 0125-0130
(2021/08/11)
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- Metal-Free Direct Deoxygenative Borylation of Aldehydes and Ketones
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Direct conversion of aldehydes and ketones into alkylboronic esters via deoxygenative borylation represents an unknown yet highly desirable transformation. Herein, we present a one-step and metal-free method for carbonyl deoxy-borylation under mild conditions. A wide range of aromatic aldehydes and ketones are tolerated and successfully converted into the corresponding benzylboronates. By the same deoxygenation manifold with aliphatic aldehydes and ketones, we also enable a concise synthesis of 1,1,2-tris(boronates), a family of compounds that currently lack efficient synthetic methods. Given its simplicity and versatility, we expect that this novel borylation approach could show great promise in organoboron synthesis and inspire more carbonyl deoxygenative transformations in both academic and industrial settings.
- Huang, Chia-Yu,Li, Chao-Jun,Li, Jianbin,Qiu, Zihang,Wang, Haining
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supporting information
p. 13011 - 13020
(2020/09/01)
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- Imine containing C2-Symmetric chiral half sandwich η6-p-cymene-Ru(II)- phosphinite complexes: Investigation of their catalytic activity in the asymmetric transfer hydrogenation of ketones
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New chiral C2-symmetric bis(phosphinite) ligands containing imine group were synthesized from 1-({[(1R,2R)-2-{[(2-hydroxynaphthalen-1-yl)methylidene] amino}cyclohexyl]- imino}methyl)- naphthalen-2-ol and two equivalents of Ph2PCl, (i-Pr)2PCl or (Cy)2PCl, in high yields. Binuclear C2-symmetric half sandwich η6-p-cymene-Ru(II) complexes of the chiral phosphinite ligands were synthesized by treating of [Ru(η6-p-cymene)(μ-Cl)Cl]2 with the phosphinites in 1:1 M ratio in CH2Cl2. Their catalytic activities in asymmetric transfer hydrogenation (ATH) were investigated for the reaction of acetophenone derivatives with isopropyl alcohol. The corresponding optically active secondary alcohols were obtained in excellent levels of conversion (96–99%) and moderate enantioselectivity (up to 60% ee). Among three complexes investigated, complex 4 was the most efficient one.
- Saleh, Najmuldain Abdullah,Pa?a, Salih,Kayan, Cezmi,Meri?, Nermin,Sünkür, Murat,Aral, Tar?k,Aydemir, Murat,Baysal, Ak?n,Durap, Feyyaz
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- Assembled Multinuclear Ruthenium(II)-NNNN Complexes: Synthesis, Catalytic Properties, and DFT Calculations
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Using a coordinatively unsaturated 16-electron mononuclear ruthenium(II)-pyrazolyl-imidazolyl-pyridine complex [Ru(II)-NNN] as the building block and oligopyridines as the polydentate ligands, pincer-type tri- A nd hexanuclear ruthenium(II) complexes [Ru(II)-NNNN]n were efficiently assembled. These complexes were characterized by elemental analyses, NMR, IR, and MALDI-TOF mass spectroscopies. In refluxing 2-propanol, the multinuclear ruthenium(II)-NNNN complexes exhibited exceptionally high catalytic activity for the transfer hydrogenation of ketones at very low concentrations and reached turnover frequencies (TOFs) up to 7.1 × 106 h-1, featuring a remarkable cooperative effect from the multiple Ru(II)-NNNN functionalities. DFT calculations have revealed the origin of the high catalytic activities of these Ru(II)-NNNN complexes.
- Liu, Tingting,Wu, Kaikai,Wang, Liandi,Fan, Hongjun,Zhou, Yong-Gui,Yu, Zhengkun
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- Ketone Hydrogenation by Using ZnO?Cu(OH)Cl/MCM-41 with a Splash of Water: An Environmentally Benign Approach
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MCM-41-supported ZnO?Cu(OH)Cl nanoparticles were synthesized via an incipient wetness impregnation technique using zinc chloride and copper chloride salts as well as water at room temperature. The catalyst was characterized by powder X-ray diffraction (PXRD), infrared spectroscopy (IR), and TGA, whereas surface and morphological studies were performed by using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The above studies revealed the incorporation of metal species into the pores of MCM-41, leading to a decrease in surface area of the nanoparticles that was found to be 239.079 m2/g. The substituents attached to the ketone determine the rate of the reaction, and the utilization of the green solvent ‘water’ astonishingly completes the hydrogenation reaction in 45 minutes at 40 °C with 100% conversion and 100% selectivity as analyzed by gas chromatography-mass spectrometry. Hence, ZnO?Cu(OH)Cl/MCM-41 nanoparticles with 2.46 wt% zinc and 6.39 wt% copper were demonstrated as an active catalyst for the reduction of ketones without using any gaseous hydrogen source making it highly efficient as well as environmentally and economically benign.
- Choudhary, Neha,Ghosh, Topi,Mobin, Shaikh M.
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p. 1339 - 1348
(2020/03/23)
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- Silver-Catalyzed Hydrogenation of Ketones under Mild Conditions
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The silver-catalyzed hydrogenation of ketones using H2 as hydrogen source is reported. Silver nanoparticles are generated from simple silver (I) salts and operate at 25 °C under 20 bar of hydrogen pressure. Various aliphatic and aromatic ketones, including natural products were reduced into the corresponding alcohols in high yields. This silver catalyst allows for the selective hydrogenation of ketones in the presence of other functional groups. (Figure presented.).
- Wang, Shengdong,Huang, Haiyun,Tsareva, Svetlana,Bruneau, Christian,Fischmeister, Cédric
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supporting information
p. 786 - 790
(2019/01/04)
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- Borinic Acid Mediated Hydrosilylations: Reductions of Carbonyl Derivatives
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4-Fluoro-2-chlorophenylborinic acid acts as a precatalyst in the presence of phenylsilane for the facile reduction of ketones, aldehydes and imines. Notably, synergistic mediation of a tertiary amine was found essential to trigger silicon to boron hydride transfer to generate a key amine–diarylhydroborane Lewis complex.
- Chardon, Aurélien,Rouden, Jacques,Blanchet, Jér?me
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supporting information
p. 995 - 998
(2018/12/13)
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- Design, Synthesis, and Application of NNN Pincer Ligands Possessing a Remote Hydroxyl Group for Ruthenium-Catalyzed Transfer Hydrogenation of Ketones
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A new family of pyridyl-based NNN pincer ligands bearing a remote pendent OH group were developed. Considerable acceleration effects on the activity of Ru-catalyzed transfer hydrogenation of ketones were imparted by the pendent OH group, and importantly, introducing a CH2OH group to the 4′-position of the pyrazolyl moiety is an appropriate choice. The results present a general strategy for exploring bifunctional ligands to construct effective catalysts.
- Cao, Zhengqiang,Qiao, Hong,Zeng, Fanlong
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p. 797 - 804
(2019/03/04)
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- Enantiodiscrimination by matrix-assisted DOSY NMR
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High-resolution NMR is an essential technique for structure determination; however, stereochemistry assignment is still an obstacle. Several methods are known to overcome this limitation but usually at high costs or using derivatizations. Here we describe the use of different solvating agents to virtually discriminate the enantiomers of 15 analytes using 1H and 19F-{1H} DOSY NMR.
- Salome, Kahlil Schwanka,Tormena, Claúdio Francisco
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supporting information
p. 8611 - 8614
(2019/07/25)
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- Hydrosilylation of carbonyl and carboxyl groups catalysed by Mn(i) complexes bearing triazole ligands
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Manganese(i) complexes bearing triazole ligands are reported as catalysts for the hydrosilylation of carbonyl and carboxyl compounds. The desired reaction proceeds readily at 80 °C within 3 hours at catalyst loadings as low as 0.25 to 1 mol%. Hence, good to excellent yields of alcohols could be obtained for a wide range of substrates including ketones, esters, and carboxylic acids illustrating the versatility of the metal/ligand combination.
- Martínez-Ferraté, Oriol,Chatterjee, Basujit,Werlé, Christophe,Leitner, Walter
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p. 6370 - 6378
(2019/11/20)
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- Transformation of Alkynes into Chiral Alcohols via TfOH-Catalyzed Hydration and Ru-Catalyzed Tandem Asymmetric Hydrogenation
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A novel full atom-economic process for the transformation of alkynes into chiral alcohols by TfOH-catalyzed hydration coupled with Ru-catalyzed tandem asymmetric hydrogenation in TFE under simple conditions has been developed. A range of chiral alcohols was obtained with broad functional group tolerance, good yields, and excellent stereoselectivities.
- Liu, Sensheng,Liu, Huan,Zhou, Haifeng,Liu, Qixing,Lv, Jinliang
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p. 1110 - 1113
(2018/02/23)
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- Rhenium and manganese complexes bearing amino-bis(phosphinite) ligands: Synthesis, characterization, and catalytic activity in hydrogenation of ketones
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A series of rhenium and manganese complexes supported by easily accessible and easily tunable amino-bisphosphinite ligands was prepared and characterized by NMR and IR spectroscopy, HR mass spectrometry, elemental analysis, and X-ray diffraction studies. These complexes have been tested in the hydrogenation of ketones. Notably, one of the rhenium complexes, bearing an NH moiety, proved significantly more active than the rest of the series. The reaction proceeds well at 120 °C, under 50 bar of H2, in the presence of 0.5 mol % of catalyst and 1 mol % of tBuOK. Interestingly, activation of the precatalyst could be followed stepwise by NMR and a rhenium hydride was characterized by X-ray diffraction studies.
- Li, Haoran,Wei, Duo,Bruneau-Voisine, Antoine,Ducamp, Maxime,Henrion, Micka?l,Roisnel, Thierry,Dorcet, Vincent,Darcel, Christophe,Carpentier, Jean-Fran?ois,Soulé, Jean-Fran?ois,Sortais, Jean-Baptiste
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supporting information
p. 1271 - 1279
(2018/04/30)
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- Iridium-catalyzed efficient reduction of ketones in water with formic acid as a hydride donor at low catalyst loading
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A highly efficient and chemoselective transfer hydrogenation of ketones in water has been successfully achieved with our newly developed catalyst. Simple ketones, as well as α- or β-functionalized ketones, are readily reduced. Formic acid is used as a traceless hydride source. At very low catalyst loading (S/C = 10:000 in most cases; S/C = 50:000 or 100:000 in some cases), the iridium catalyst is impressively efficient at reducing ketones in good to excellent yields. The TOF value can be as high as up to 26:000 mol mol-1 h-1. A variety of functional groups are well tolerated, for example, heteroaryl, aryloxy, alkyloxy, halogen, cyano, nitro, ester, especially acidic methylene, phenol and carboxylic acid groups.
- Liu, Ji-Tian,Yang, Shiyi,Tang, Weiping,Yang, Zhanhui,Xu, Jiaxi
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supporting information
p. 2118 - 2124
(2018/05/24)
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- Ruthenium NNN complexes with a 2-hydroxypyridylmethylene fragment for transfer hydrogenation of ketones
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Four NNN tridentate ligands L1–L4 containing 2-methoxypyridylmethene or 2-hydroxypyridylmethene fragment were synthesized and introduced to ruthenium centers. When (HOC5H3NCH2C5H3NC5H7N2) (L2) and (HOC5H3NCH2C5H3NC6H6N3) (L4) reacted with RuCl2(PPh3)3, two ruthenium chloride products Ru(L2)(PPh3)Cl2 (1) and Ru(L4)(PPh3)Cl2 (2) were isolated, respectively. Reactions of (MeOC5H3NCH2C5H3NC5H7N2) (L1) and (MeOC5H3NCH2C5H3NC6H6N3) (L3) with RuCl2(PPh3)3 in the presence of NH4PF6 generated two dicationic complexes [Ru(L1)2][PF6]2 (3) and [Ru(L3)2][PF6]2 (4), respectively. Complex 1 reacted with CO to afford product [Ru(L2)(PPh3)(CO)Cl][Cl]. The catalytic activity for transfer hydrogenation of ketones was investigated. Complex 1 showed the highest activity, with a turnover frequency value of 1.44?×?103?h?1 for acetophenone, while complexes 3 and 4 were not active.
- Shi, Jing,Shang, Shu,Hu, Bowen,Chen, Dafa
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- Chiral C2-symmetric η6-p-cymene-Ru(II)-phosphinite complexes: Synthesis and catalytic activity in asymmetric reduction of aromatic, methyl alkyl and alkyl/aryl ketones
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Chiral C2-symmetric bis(phosphinite) ligands and their binuclear ruthenium(II) complexes have been synthesized and used as catalysts in the ruthenium-catalyzed asymmetric transfer hydrogenation of aromatic, methyl alkyl and alkyl/aryl ketones using 2-propanol as both the hydrogen source and solvent in the presence of KOH. Under optimized conditions, all complexes showed high catalytic activity as catalysts in the reduction of various ketones to corresponding chiral secondary alcohols. Products were obtained with high conversions (99%) and moderate to good enantioselectivities (82% ee). Furthermore, C2-symmetric bis(phosphinite) ligands and their binuclear ruthenium(II) complexes were characterized by multinuclear NMR spectroscopy, FT-IR spectroscopy, LC/MS-MS and elemental analysis.
- Karaka?, Duygu Elma,Aydemir, Murat,Durap, Feyyaz,Baysal, Ak?n
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p. 430 - 439
(2017/12/06)
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- Aminotriazole Mn(I) Complexes as Effective Catalysts for Transfer Hydrogenation of Ketones
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A catalytic system based on complexes comprising abundant and cheap manganese together with readily available aminotriazole ligands is reported. The new Mn(I) complexes are catalytically competent in transfer hydrogenation of ketones with 2-propanol as hydrogen source. The reaction proceeds under mild conditions at 80 °C for 20 h with 3 % of catalyst loading using either KOtBu or NaOH as base. Good to excellent yields were obtained for a wide substrate scope with broad functional group tolerance. The obtained results by varying the substitution pattern of the ligand are consistent with an out-sphere mechanism for the H-transfer.
- Martínez-Ferraté, Oriol,Werlé, Christophe,Franciò, Giancarlo,Leitner, Walter
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p. 4514 - 4518
(2018/10/20)
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- Exploring Tandem Ruthenium-Catalyzed Hydrogen Transfer and SNAr Chemistry
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A hydrogen-transfer strategy for the catalytic functionalization of benzylic alcohols via electronic arene activation, accessing a diverse range of bespoke diaryl ethers and aryl amines in excellent isolated yields (38 examples, 70% average yield), is reported. Taking advantage of the hydrogen-transfer approach, the oxidation level of the functionalized products can be selected by judicious choice of simple and inexpensive additives.
- Polidano, Kurt,Reed-Berendt, Benjamin G.,Basset, Ana?s,Watson, Andrew J. A.,Williams, Jonathan M. J.,Morrill, Louis C.
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supporting information
p. 6716 - 6719
(2017/12/26)
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- Cooperative N-H and CH2 Skeleton Effects on the Catalytic Activities of Bimetallic Ru(II)-NNN Complexes: Experimental and Theoretical Study
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Bimetallic ruthenium(II) complexes bearing a bis(pyrazolylimidazolylpyridine) ligand bridged by a rotatable single C-C bond or methylene linker were synthesized, structurally characterized, and exhibited diverse catalytic activities for the transfer hydrogenation (TH) reactions of ketones in refluxing isopropyl alcohol. Both the unprotected NH functionality and bridging methylene moiety demonstrated an acceleration effect on such TH reactions. Combination of the NH and CH2 skeleton functionalities into the bimetallic Ru(II)-NNN complexes remarkably enhanced the catalytic activities of the complex catalysts. Density functional theory calculations have suggested that the difference in the catalytic activities of these Ru(II)-NNN complexes is attributed to the inherent nucleophilic character of the coordinative nitrogen atoms in the bis(NNN) ligand, and the metal-metal interaction resulted from the number of net natural bond orbital charges on these nitrogen atoms.
- Chai, Huining,Liu, Tingting,Zheng, Daoyuan,Yu, Zhengkun
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p. 4268 - 4277
(2017/11/20)
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- Dual cobalt-copper light-driven catalytic reduction of aldehydes and aromatic ketones in aqueous media
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We present an efficient, general, fast, and robust light-driven methodology based on earth-abundant elements to reduce aryl ketones, and both aryl and aliphatic aldehydes (up to 1400 TON). The catalytic system consists of a robust and well-defined aminopyridyl cobalt complex active for photocatalytic water reduction and the [Cu(bathocuproine)(Xantphos)](PF6) photoredox catalyst. The dual cobalt-copper system uses visible light as the driving-force and H2O and an electron donor (Et3N or iPr2EtN) as the hydride source. The catalytic system operates in aqueous mixtures (80-60% water) with high selectivity towards the reduction of organic substrates (>2000) vs. water reduction, and tolerates O2. High selectivity towards the hydrogenation of aryl ketones is observed in the presence of terminal olefins, aliphatic ketones, and alkynes. Remarkably, the catalytic system also shows unique selectivity for the reduction of acetophenone in the presence of aliphatic aldehydes. The catalytic system provides a simple and convenient method to obtain α,β-deuterated alcohols. Both the observed reactivity and the DFT modelling support a common cobalt hydride intermediate. The DFT modelled energy profile for the [Co-H] nucleophilic attack to acetophenone and water rationalises the competence of [CoII-H] to reduce acetophenone in the presence of water. Mechanistic studies suggest alternative mechanisms depending on the redox potential of the substrate. These results show the potential of the water reduction catalyst [Co(OTf)(Py2Tstacn)](OTf) (1), (Py2Tstacn = 1,4-di(picolyl)-7-(p-toluenesulfonyl)-1,4,7-triazacyclononane, OTf = trifluoromethanesulfonate anion) to develop light-driven selective organic transformations and fine solar chemicals.
- Call, Arnau,Casadevall, Carla,Acu?a-Parés, Ferran,Casitas, Alicia,Lloret-Fillol, Julio
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p. 4739 - 4749
(2017/07/10)
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- Mechanistic Studies on Ruthenium(II)-Catalyzed Base-Free Transfer Hydrogenation Triggered by Roll-Over Cyclometalation
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The synthesis of 2-substituted pyridine–pyrimidine ligands and their complexation with arene ruthenium(II) chloride moieties is reported. Depending on the electronic and steric influences of the ligand, the catalysts undergo CH activation by roll-over cyclometalation. This process opens up the route to the catalytic transfer hydrogenation of ketones with isopropanol as the hydrogen source under base-free and mild conditions. Barriers related to the roll-over cyclometalation process can be determined experimentally by collision-induced dissociation ESI mass spectrometry. They are supported by DFT calculations and allow the classification of the ligands according to their electronic and steric properties, which is also in accordance with critical bond parameters derived from X-ray structure data. DFT calculations furthermore reveal that the formation of a ruthenium(II) hydrido species is plausible through β-hydride elimination from isopropanol.
- Kerner, Christian,Lang, Johannes,Gaffga, Maximilian,Menges, Fabian S.,Sun, Yu,Niedner-Schatteburg, Gereon,Thiel, Werner R.
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p. 212 - 224
(2017/03/07)
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- Dimeric Ruthenium(II)-NNN Complex Catalysts Bearing a Pyrazolyl-Pyridylamino-Pyridine Ligand for Transfer Hydrogenation of Ketones and Acceptorless Dehydrogenation of Alcohols
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Dimeric pincer-type ruthenium(II)-NNN complexes bearing an unsymmetrical pyrazolyl-pyridylamino-pyridine ligand were prepared and characterized by NMR, elemental analysis, and X-ray single crystal structural determination. These complexes exhibited very high catalytic activity for both transfer hydrogenation of ketones and acceptorless dehydrogenation of secondary alcohols, achieving TOF values up to 1.9 × 106 h-1 in the transfer hydrogenation of ketones. The high catalytic activity of the Ru(II) complex catalysts is attributed to the presence of the unprotected NH functionality in the ligand and hemilabile unsymmetrical coordination environment around the central metal atoms in the complex.
- Wang, Qingfu,Chai, Huining,Yu, Zhengkun
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p. 3638 - 3644
(2017/10/03)
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- Exceptionally Active Assembled Dinuclear Ruthenium(II)-NNN Complex Catalysts for Transfer Hydrogenation of Ketones
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Dinuclear ruthenium(II)-NNN complexes were efficiently assembled by means of coordinatively unsaturated 16-electron mononuclear ruthenium(II)-pyrazolyl-imidazolyl-pyridine complex and 4,4′-linked bipyridine ligands. The diruthenium(II)-NNN complex assembled through 4,4′-(CH2)3-bipyridine exhibited exceptionally high catalytic activity for the transfer hydrogenation (TH) of ketones in refluxing 2-propanol and reached TOF values up to 1.4 × 107 h-1, demonstrating a remarkable cooperative effect from the ruthenium(II)-NNN functionalities.
- Liu, Tingting,Chai, Huining,Wang, Liandi,Yu, Zhengkun
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p. 2914 - 2921
(2017/08/22)
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- Transfer hydrogenation of ketones catalysed by half-sandwich (η6-p-cymene) ruthenium(II) complexes incorporating benzoylhydrazone ligands
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Neutral half-sandwich η6-p-cymene ruthenium(II) complexes of general formula [Ru(η6-p-cymene)Cl(L)] (HL?=?monobasic O, N bidendate benzoylhydrazone ligand) have been synthesized from the reaction of [Ru(η6-p-cymene)(μ-Cl)Cl]2 with acetophenone benzoylhydrazone ligands. All the complexes have been characterized using analytical and spectroscopic (Fourier transform infrared, UV–visible, 1H NMR, 13C NMR) techniques. The molecular structures of three of the complexes have been determined using single-crystal X-ray diffraction, indicating a pseudo-octahedral geometry around the ruthenium(II) ion. All the ruthenium(II) arene complexes were explored as catalysts for transfer hydrogenation of a wide range of aromatic, cyclic and aliphatic ketones with 2-propanol using 0.1?mol% catalyst loading, and conversions of up to 100% were obtained. Further, the influence of other variables on the transfer hydrogenation reaction, such as base, temperature, catalyst loading and substrate scope, was also investigated.
- Mohan, Nanjan,Ramesh, Rengan
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- Efficient and recyclable Ru(II) arene thioamide catalysts for transfer hydrogenation of ketones: Influence of substituent on catalytic outcome
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Six cationic ruthenium(II) arene thioamide complexes with the general molecular formula [Ru(η6-p-cymene)(PPh3)(L)]+ [where, L = pyridine-2-thioamide and its derivatives] have been successfully synthesized from the reaction of [Ru(η6-p-cymene)Cl2]2 with chelating thioamide ligands and PPh3 in methanol in 1:2 M ratio respectively. All the complexes were isolated as their BPh4?salts and were fully characterized by analytical and spectral (FT-IR, UV-Vis and1H-NMR) methods. The solid-state structure of one of the complexes, [Ru(η6-p-cymene)(PPh3)(L4)]BPh4 (4) (L4 = N-(2, 4, 6-Trimethylphenyl)pyridine-2-thiocarboxamide) has been established by X-ray single crystal diffraction which indicates a pseudo-octahedral (piano-stool) coordination geometry is present in the complex. The ruthenium(II) complexes have been examined for the transfer hydrogenation of various aromatic, heterocycle and cyclic ketones. The formation of ruthenium(II) hydride is confirmed by 1H- NMR and is proposed as the catalytic intermediate in this reaction. Under the optimized conditions, these ruthenium complexes served as excellent catalyst precursors which smoothly reduce the ketones with conversion up to 100%. The influence of other variables on the transfer hydrogenation reaction such as solvent, base, temperature, time, catalyst loading and substrate scope is also reported. Furthermore, the catalyst could be easily recovered and reused at least three times without obvious loss of conversions.
- Kanchanadevi, Appukutti,Ramesh, Rengan,Semeril, David
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- Ruthenium complexes bearing an unsymmetrical pincer ligand with a 2-hydroxypyridylmethylene fragment: Active catalysts for transfer hydrogenation of ketones
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Five ruthenium(ii) complexes were synthesized, including (HO-C5H3N-CH2-C5H3N-C5H4N)Ru(PPh3)Cl2 (3), [(HO-C5H3N-CH2-C5H3N-C5H4N)Ru(PPh3)2Cl][PF6] (4) and [(HO-C5H3N-CH2-C5H3N-C5H4N)Ru(PPh3)2OH][PF6] (5) bearing an unsymmetrical pincer NNN ligand with a 2-hydroxypyridylmethylene fragment, and [(CH3O-C5H3N-CH2-C5H3N-C5H4N)2Ru][Cl]2 (6) and [(CH3O-C5H3N-CH2-C5H3N-C5H4N)2Ru][PF6]2 (7) containing 2-methoxypyridylmethylene moieties. 4 reacts with H2O at room temperature to give 5 whose crystal structure reveals the existence of intramolecular hydrogen-bonding between its two -OH groups. 3 exhibits high catalytic activity for transfer hydrogenation of ketones.
- Shi, Jing,Hu, Bowen,Gong, Dawei,Shang, Shu,Hou, Guangfeng,Chen, Dafa
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p. 4828 - 4834
(2016/03/19)
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- Highly Active and Selective Manganese C=O Bond Hydrogenation Catalysts: The Importance of the Multidentate Ligand, the Ancillary Ligands, and the Oxidation State
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The replacement of expensive noble metals by earth-abundant transition metals is a central topic in catalysis. Herein, we introduce a highly active and selective homogeneous manganese-based C=O bond hydrogenation catalyst. Our catalyst has a broad substrate scope, it is able to hydrogenate aryl–alkyl, diaryl, dialkyl, and cycloalkyl ketones as well as aldehydes. A very good functional group tolerance including the quantitative and selective hydrogenation of a ketone in the presence of a non-shielded olefin is observed. In Mn hydrogenation catalysis, the combination of the multidentate ligand, the oxidation state of the metal, and the choice of the right ancillary ligand is crucial for high activity. This observation emphasizes an advantage and the importance of homogeneous catalysts in 3d-metal catalysis. For coordination compounds, fine-tuning of a complex coordination environment is easily accomplished in comparison to enzyme and/or heterogeneous catalysts.
- Kallmeier, Fabian,Irrgang, Torsten,Dietel, Thomas,Kempe, Rhett
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supporting information
p. 11806 - 11809
(2016/11/16)
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- Diruthenium(II)-NNN pincer complex catalysts for transfer hydrogenation of ketones
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Dinuclear ruthenium(ii)-NNN pincer complexes bearing a π linker-supported bis(pyrazolyl-imidazolyl-pyridine) ligand were synthesized and structurally characterized, and they exhibited excellent catalytic activity for the transfer hydrogenation of ketones in refluxing isopropanol, reaching TOF values up to 1.3 × 106 h-1. Compared with the corresponding mononuclear Ru(ii)-NNN pincer complexes, the bimetallic complexes could be applied at concentrations as low as 0.03 mol% Ru and demonstrated remarkably enhanced catalytic activity in the transfer hydrogenation reactions of ketones. The high catalytic activity of the diruthenium(ii) complexes is attributed to the excellent stability and possible cooperativity of the two coordinated Ru(ii) metal centers through the π linker. The present synthetic methodology has established an applicable strategy to construct highly active bimetallic NNN pincer complex catalysts.
- Chai, Huining,Wang, Qingfu,Liu, Tingting,Yu, Zhengkun
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p. 17843 - 17849
(2016/11/18)
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- New Type of 2,6-Bis(imidazo[1,2-a]pyridin-2-yl)pyridine-Based Ruthenium Complexes: Active Catalysts for Transfer Hydrogenation of Ketones
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Neutral and cationic ruthenium(II) complexes bearing a symmetrical 2,6-bis(imidazo[1,2-a]pyridin-2-yl)pyridine were synthesized and structurally characterized by NMR analysis and X-ray crystallographic determinations. These complexes have exhibited good catalytic activity in the transfer hydrogenation of ketones. In refluxing isopropyl alcohol, the conversion of the substrates reached up to 99%, and a TOF value of 356400 h-1 with 0.1 mol % catalyst was achieved. (Figure Presented).
- Li, Ke,Niu, Jun-Long,Yang, Ming-Ze,Li, Zhen,Wu, Li-Yuan,Hao, Xin-Qi,Song, Mao-Ping
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p. 1170 - 1176
(2015/04/27)
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- Ruthenium(II) complexes derived from C2-symmetric ferrocene-based chiral bis(phosphinite) ligands: Synthesis and catalytic activity towards the asymmetric reduction of acetophenones
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Chiral secondary alcohols are very important building blocks and valuable synthetic intermediates both in organic synthesis and in the pharmaceutical industry for producing biologically active complex molecules. A series of new chiral Ru-phosphinite complexes (1, 2, 3, 4, 5, 6, 7, 8) were prepared from chiral C2-symmetric ferrocenyl phosphinites and corresponding chloro complex, [Ru(η6-p-cymene)(μ-Cl)Cl]2. The complexes were characterized using conventional spectroscopic methods. The binuclear complexes were tested as pre-catalysts and were found to be good pre-catalysts for the asymmetric transfer hydrogenation of substituted acetophenones in basic 2-propanol at 82° C, providing the corresponding optically active alcohols with almost quantitative conversion and modest to high enantioselectivities (46-97%). Amongst the all complexes, complex 6 gave the highest ee of 97% in the reduction of 2-methoxyacetophenone to (S)-1-(2-methoxyphenyl)ethanol at 82° C.
- Ak,Durap,Aydemir,Baysal
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p. 764 - 770
(2015/11/09)
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- Substituent Effect on the Catalytic Activity of Ruthenium(II) Complexes Bearing a Pyridyl-Supported Pyrazolyl-Imidazolyl Ligand for Transfer Hydrogenation of Ketones
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Air- and moisture-stable ruthenium(II) complexes bearing a multisubstituted pyrazolyl-imidazolyl-pyridine ligand were synthesized and structurally characterized by NMR and X-ray single-crystal crystallographic analyses. The substituents on the imidazolyl moiety of the NNN ligand exhibited a remarkable impact on the catalytic activity of the corresponding Ru(II) complexes for transfer hydrogenation of ketones in refluxing 2-propanol, following the order NHTs > Me > H > NO2, to tune the catalytic activity. The highest final TOF value of 345 600 h-1 was reached by means of 0.05 mol % of the Ru(II)-NHTs-substituted NNN complex as the catalyst. The corresponding structurally confirmed RuH complexes are proposed as the catalytically active species.
- Chai, Huining,Liu, Tingting,Wang, Qingfu,Yu, Zhengkun
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p. 5278 - 5284
(2015/11/18)
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- Homogeneous and heterogeneous photoredoxcatalyzed hydroxymethylation of ketones and keto esters: Catalyst screening, chemoselectivity and dilution effects
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The homogeneous titanium- and dye-catalyzed as well as the heterogeneous semiconductor particle-catalyzed photohydroxymethylation of ketones by methanol were investigated in order to evaluate the most active photocatalyst system. Dialkoxytitanium dichlorides are the most efficient species for chemoselective hydroxymethylation of acetophenone as well as other aromatic and aliphatic ketones. Pinacol coupling is the dominant process for semiconductor catalysis and ketone reduction dominates the Ti(OiPr)4/methanol or isopropanol systems. Application of dilution effects on the TiO2 catalysis leads to an increase in hydroxymethylation at the expense of the pinacol coupling.
- Griesbeck, Axel G.,Reckenthaeler, Melissa
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supporting information
p. 1143 - 1150
(2014/06/09)
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- Dye-sensitized photo-hydrogenation of aromatic ketones on titanium dioxide under visible light irradiation
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Aromatic ketones were photocatalytically hydrogenated on P25 TiO 2 powder modified with metal free organic dyes under visible light irradiation. The suitable combination of dye-TiO2 and triethylamine as a sacrificial electron donor successfully extended the photocatalytic UV response of TiO2 toward visible light region in the photo-hydrogenation of acetophenone derivatives.
- Kohtani, Shigeru,Nishioka, Saki,Yoshioka, Eito,Miyabe, Hideto
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- Novel half-sandwich η5-Cp *-rhodium(III) and η5-Cp *-ruthenium(II) complexes bearing bis(phosphino)amine ligands and their use in the transfer hydrogenation of aromatic ketones
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Two new half-sandwich η5-Cp*-rhodium(III) and η5-Cp*-ruthenium(II) complexes have been prepared from corresponding bis(phosphino)amine ligands, thiophene-2-(N,N- bis(diphenylphosphino)methylamine) or furfuryl-2-(N,N-bis(diphenylphosphino) amine). Structures of the new complexes have been elucidated by multinuclear one- and two-dimensional NMR spectroscopy, elemental analysis and IR spectroscopy. These Cp*-rhodium(III) and Cp*-ruthenium(II) complexes bearing bis(phosphino)amine ligands were successfully applied to transfer hydrogenation of various ketones by 2-propanol. Copyright
- Ok, Fatih,Aydemir, Murat,Durap, Feyyaz
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- Ruthenium complex catalysts supported by a bis(trifluoromethyl)pyrazolyl- pyridyl-based NNN ligand for transfer hydrogenation of ketones
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Ru(III) and Ru(II) complexes bearing a tridentate 2-(3′,5′- dimethylpyrazol-1′-yl)-6-(3″,5″-bis(trifluoromethyl) pyrazol-1″-yl)pyridine or 2-(benzimidazol-2′-yl)-6-(3″, 5″-bis(trifluoromethyl)pyrazol-1″-yl)pyridine ligand were synthesized and applied to the transfer hydrogenation of ketones. The Ru(II) complex was structurally confirmed by the X-ray crystallographic analysis and achieved up to 2150 turnover numbers and final TOFs up to 29700 h-1 in the transfer hydrogenation of ketones. The benzimidazolyl moiety with an unprotected NH functionality in the ligand exhibited an enhancement effect on the catalytic activity of its RuCl3 complex in the ketone reduction reactions, reaching a final TOF value up to 35640 h-1. The controlled experiments have revealed that the compatibility of the trifluoromethylated pyrazolyl and unprotected benzimidazolyl is crucial for the establishment of the highly active catalytic system.
- Du, Wangming,Wang, Qingfu,Wang, Liandi,Yu, Zhengkun
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p. 974 - 982
(2014/03/21)
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- Kinetic study on photocatalytic hydrogenation of acetophenone derivatives on titanium dioxide
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Acetophenone (AP) derivatives were photocatalytically hydrogenated to afford the corresponding secondary alcohols with excellent chemical efficiencies on titanium dioxide (Degussa P25, TiO2) under UV light irradiation. Maximum reaction rates (kmax) and apparent adsorption constants (KLH) under irradiation were obtained from the Langmuir-Hinshelwood kinetic analysis. The kmax values showed a tendency to decrease with the decreasing reduction potentials (Ered) of the AP derivatives, while the KLH values were distributed in the range of 280-780 L mol-1. Among these, simple AP exhibited the greatest adsorptivity upon the UV irradiated TiO2 surface. Additionally, it was demonstrated that the electrons trapped at surface defect Ti (Tist) sites on the TiO2 actually hydrogenated the AP derivatives. The amount of reacted electrons also showed a tendency to decrease with decreasing Ered values, in accord with the dependence on kmax. These results indicate that the electrons accumulated at shallow Tist states easily participate in the hydrogenation of AP derivatives, whereas those trapped at deeper states hardly react with the substrates. The results strongly support the electron transfer reaction model via the Tist sites in the photocatalytic hydrogenation on TiO2. This journal is the Partner Organisations 2014.
- Kohtani, Shigeru,Kamoi, Yuna,Yoshioka, Eito,Miyabe, Hideto
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p. 1084 - 1091
(2014/04/03)
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- Construction of pincer-type symmetrical ruthenium(II) complexes bearing pyridyl-2,6-pyrazolyl arms: Catalytic behavior in transfer hydrogenation of ketones
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Convenient synthesis of four new distorted octahedral ruthenium(II) complexes (1, 2, 3, 4) having general molecular formula [RuCl2LPAr3] (L = pyridine-based tridentate ligands not containing N-H bonds) is described. Their composition and structure were determined by elemental analysis and NMR spectra, and complexes 2 and 4 were also identified by X-ray single-crystal diffraction. All ruthenium(II) complexes exhibited good to excellent catalytic activity in the transfer hydrogenation of ketones. Among them, complex 4 achieved the highest final TOF value of 51600 h-1 for a high molar ratio of substrate to catalyst (2000:1).
- Zhu, Zhu,Zhang, Jie,Fu, Haiyan,Yuan, Maolin,Zheng, Xueli,Chen, Hua,Li, Ruixiang
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p. 52734 - 52739
(2015/01/09)
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- Cyclometalated iridium complexes for transfer hydrogenation of carbonyl groups in water
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Cyclometalated iridium complexes are shown to be excellent catalysts for transfer hydrogenation of carbonyl compounds in water using formate as a hydrogen source. A wide range of ketones and aldehydes have been reduced at 0.05% catalyst loading with no need for any organic solvents. Solution pH is found to play a critical role, with acidic conditions needed for fast transfer hydrogenation.
- Wei, Yawen,Xue, Dong,Lei, Qian,Wang, Chao,Xiao, Jianliang
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supporting information
p. 629 - 634
(2013/04/10)
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- Ruthenium(II) half-sandwich complexes containing thioamides: Synthesis, structures and catalytic transfer hydrogenation of ketones
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A new family of cationic half-sandwich complexes of the type [(η6-cymene)Ru(PPh3)(L)]+ (L = bidentate monoanionic thioamide) have been synthesized and isolated as their tetraphenylborate salts. All the synthesized ruthenium(II) arene complexes are air stable and are fully characterized by elemental analysis, spectral and X-ray diffraction methods. In chloroform solution all the complexes exhibit characteristic metal to ligand charge transfer (MLCT) absorptions and ligand based transitions. Molecular structure of the complexes 2, 3 and 4 has been determined by single crystal X-ray crystallography indicates that the thioamide ligands are coordinated to ruthenium as a bidentate O, S donor and a typical piano stool geometry was observed around ruthenium(II) metal center. Complexes 1-5 were tested as catalysts in the transfer hydrogenation of aliphatic and aromatic ketones to secondary alcohols in the presence of 2-propanol/KOH. Further, the influence of base, reaction temperature and catalyst loading in this reaction was also evaluated to find out the most active catalyst.
- Pandiarajan, Devaraj,Ramesh, Rengan
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- Ruthenium(II) complex catalysts bearing a pyridyl-based benzimidazolyl-benzotriazolyl ligand for transfer hydrogenation of ketones
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Air- and moisture-stable ruthenium(II) complexes bearing a unsymmetrical 2-(benzimidazol-2-yl)-6-(benzotriazol-1-yl)pyridine ligand were synthesized and structurally characterized by NMR analysis and X-ray crystallographic determinations. These complexes have exhibited excellent catalytic activity in the transfer hydrogenation of ketones in refluxing 2-propanol, reaching final TOFs up to 176400 h-1. The corresponding RuH complex was isolated and is proposed as the catalytically active species by controlled experiments. The high catalytic activity of the Ru(II) the complex catalysts is attributed to the hemilabile unsymmetrical coordinating environment around the central metal atom in the complexes and presence of a convertible benzimidazolyl NH functionality in the ligand.
- Du, Wangming,Wu, Ping,Wang, Qingfu,Yu, Zhengkun
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p. 3083 - 3090
(2013/07/04)
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- Use of tridentate TsDPEN/pyridine ligands in ruthenium-catalysed asymmetric reduction of ketones
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A series of enantiomerically pure tridentate ligands based on the 1,2-diphenylethane-1,2-diamine structure, containing additional pyridine groups, was prepared and tested in asymmetric transfer hydrogenation of ketones using Ru3(CO)12 as a metal source. Alcohols were formed in up to 93% ee in the best cases, and good results were obtained with ortho-haloarylketones.
- Darwish, Moftah O.,Wallace, Alistair,Clarkson, Guy J.,Wills, Martin
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supporting information
p. 4250 - 4253
(2013/07/26)
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- Regioselective reductive hydration of alkynes to form branched or linear alcohols
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The regioselective reductive hydration of terminal alkynes using two complementary dual catalytic systems is described. Branched or linear alcohols are obtained in 75-96% yield with ?25:1 regioselectivity from the same starting materials. The method is compatible with terminal, di-, and trisubstituted alkenes. This reductive hydration constitutes a strategic surrogate to alkene oxyfunctionalization and may be of utility in multistep settings.
- Li, Le,Herzon, Seth B.
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supporting information
p. 17376 - 17379,4
(2020/09/16)
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- NHC-catalyzed chemo- and regioselective hydrosilylation of carbonyl derivatives
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The hydrosilylation of carbonyl derivatives has been explored by the activation of diphenylsilane in the presence of a catalytic amount of an N-heterocyclic carbene (NHC). Presumably, a hypervalent silicon intermediate featuring strong Lewis acid character allows dual activation of both the carbonyl moiety and the hydride at the silicon center. Reduction under mild conditions could be accomplished using this organocatalytic process. Some interesting selectivities have been encountered. Georg Thieme Verlag Stuttgart · New York.
- Zhao, Qiwu,Curran, Dennis P.,Malacria, Max,Fensterbank, Louis,Goddard, Jean-Philippe,Lac?te, Emmanuel
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supporting information; experimental part
p. 433 - 437
(2012/03/10)
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- Efficient and selective hydrosilylation of carbonyl compounds catalyzed by iron acetate and N-hydroxyethylimidazolium salts
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Aromatic aldehydes, along with aryl alkyl, heteroaryl alkyl, and dialkyl ketones were efficiently reduced to their corresponding primary and secondary alcohols, respectively, in high yields, using the commercially available and inexpensive polymeric silane, polymethylhydrosiloxane (PMHS), as reducing agent. The reaction is catalyzed by in situ generated iron complexes containing hydroxyethyl-functionalized NHC ligands. Turnover frequencies up to 600 h-1 were obtained.
- Buitrago, Elina,Tinnis, Fredrik,Adolfsson, Hans
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supporting information; experimental part
p. 217 - 222
(2012/03/27)
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- Enantioselective addition of phenylacetylene to aldehydes catalyzed by a d-glucosamine-derived sulfonamide-titanium complex
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We present the synthesis of β-hydroxy sulfonamides derived from d-glucosamine and their application as ligands in titanium tetraisopropoxide promoted enantioselective addition of phenylacetylene to benzaldehyde and selected aromatic and aliphatic aldehydes. The N-3,5-bis(trifluoromethyl) benzenesulfonamido-d-glucosamine derivative was chosen as the most efficient ligand for this addition. The reaction is highly enantioselective for several aromatic aldehydes and enantiomeric excesses up to 92% were obtained.
- Bauer, Tomasz,Smoliński, S?awomir,Gawe?, Przemys?aw,Jurczak, Janusz
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experimental part
p. 4882 - 4884
(2011/10/05)
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- MPV reduction using AlIII-calix[4]arene Lewis acid catalysts: Molecular-level insight into effect of ketone binding
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Catalytic Meerwein-Ponndorf-Verley (MPV) reduction using Al III-calix[4]arene complexes is investigated as a model system that requires the bringing together of two different chemical species, ketone and alkoxide, within a six-membered transition state. Two-point versus one-point ketone binding is demonstrated to be the most salient feature that controls MPV catalysis rate. A 7.7-fold increase in rate is observed when comparing reactants consisting of a bidentate Cl-containing ketone and sterically and electronically similar but looser-binding ketones, which are substituted with H and F. The one-point and two-point nature of ketone binding for the various ketones investigated is independently assessed using a combination of structural data derived from single-crystal X-ray diffraction and DFT-based molecular modeling. Using MPV catalysis with inherently chiral calix[4]arenes, the effect of multiple point reactant binding on enantioselectivity is elucidated. A higher denticity of ketone binding appears to increase the sensitivity of the interplay between chiral active site structure and MPV reduction enantioselectivity.
- Nandi, Partha,Matvieiev, Yuriy I.,Boyko, Vyacheslav I.,Durkin, Kathleen A.,Kalchenko, Vitaly I.,Katz, Alexander
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experimental part
p. 42 - 49
(2011/12/13)
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- A RuII-N-heterocyclic carbene (NHC) complex from metal-metal singly bonded diruthenium(I) precursor: Synthesis, structure and catalytic evaluation
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A mononuclear Ru(II)-N-heterocyclic carbene (NHC) complex [Ru II(CO)2(κ2C,N-BIN)(H2O)Br] [OTf] (OTf = trifluoromethane sulphonate) (1) has been synthesized in high-yield by the oxidative cleavage of the metal-metal singly-bonded diruthenium(I) precursor [Ru2(CO)4(CH3CN)6(OTf) 2] with 1,8-naphthyridine functionalized NHC precursor 1-benzyl-3-(5,7-dimethyl-1,8-naphthyrid-2-yl)imidazolium bromide (BIN·HBr) at room temperature. Compound 1 catalyzes transfer hydrogenation of ketones to alcohols, and carbene-transfer from ethyl diazoacetate to a variety of substrates. It is shown to be an excellent catalyst for the insertion of carbene into the O-H and N-H bonds of alcohols and amines.
- Sinha, Arup,Daw, Prosenjit,Rahaman, S.M. Wahidur,Saha, Biswajit,Bera, Jitendra K.
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experimental part
p. 1248 - 1257
(2011/04/22)
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