- Novel N-coordinate half-sandwich ruthenium(II) arene complexes bearing sulfonamide fragments: Catalytic activities in the TH of acetophenone derivatives
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Abstract The novel cationic N-coordinate ruthenium(II)/arene complexes (6-10) were prepared from the starting complex [RuCl2(p-cymene)]2 dimer. The structures of the [(p-cymene)RuLCl]Cl (L = N-arenesulfonyl-4,5-dimethyl-o-phenylenedi
- Kayaci, Nilgün,Dayan, Serkan,Kalaycioglu Ozpozan, Nilgun
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- Synthesis and catalytic activity of semiconducting p-cymene ruthenium 1,3,4-thiadiazole and 1,2,4-triazole complexes
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The novel ruthenium(II) complexes containing 5-(pyridin-4-yl)-1,3,4- thiadiazol-2-amine(1) and 4-amino-5-(pyridin-4-yl)-4H-1,2,4-triazole-3-thiol (2) ligands were synthesized and characterized by UV-Vis, IR, NMR, and elemental analysis. The complexes have
- Serbetci, Zafer
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- Catalytic transfer hydrogenation and anticancer activity of arene-ruthenium compounds incorporating bi-dentate precursors
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Ruthenium based organometallic compounds are presently a subject of great attention as anticancer drugs and appear to work reasonably well on tumor cells. We develop a series of mononuclear arene-ruthenium compounds incorporating N,O and N,N bidentate lig
- Chang, Yu-Hsiang,Leu, Wohn-Jenn,Datta, Amitabha,Hsiao, Hung-Chang,Lin, Chia-Her,Guh, Jih-Hwa,Huang, Jui-Hsien
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- Ruthenium(II) carbonyl chloride complexes containing pyridine- functionalised bidentate N-heterocyclic carbenes: Synthesis, structures, and impact of the carbene ligands on catalytic activities
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A series of new ruthenium(II) carbonyl chloride complexes with pyridine-functionalised N-heterocyclic carbenes [Ru(Py-NHC)(CO) 2Cl2], [Py-NHC = 3-methyl-1-(2-pyridyl)imidazol-2-ylidene, 1 (1a and 1b); 3-methyl-1-(2-picoyl)imidazol-2-
- Li, Xiao-Wei,Wang, Gao-Feng,Chen, Fei,Li, Yi-Zhi,Chen, Xue-Tai,Xue, Zi-Ling
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- Preparation, characterization, and catalytic properties of ruthenium nitrosyl complexes with polypyrazolylmethane ligands
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Ruthenium(II) nitrosyl complexes with polypyrazolylmethanes, [(Bpm)Ru(NO)Cl3] [Bpm = bis(1-pyrazolyl)methane, 1], [(Bpm*)Ru(NO)Cl3] [Bpm* = bis(3,5-dimethyl-1-pyrazolyl)methane, 2], [(Tpm)Ru(NO)Cl2][P
- Xu, Hui-Jun,Cheng, Yong,Sun, Jia-Feng,Dougan, Brenda A.,Li, Yi-Zhi,Chen, Xue-Tai,Xue, Zi-Ling
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- Synthesis, structures and catalytic activities of ruthenium(ii) carbonyl chloride complexes containing pyridine-functionalised N-heterocyclic carbenes
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A series of ruthenium(ii) carbonyl chloride complexes with pyridine-functionalised N-heterocyclic carbenes, trans(Cl)- and cis(Cl)-[Ru(Py-NHC)(CO)2Cl2] [Py-NHC = 3-tert-butyl-1-(2-pyridyl)imidazol-2-ylidene, 1a and 1b; 3-n-butyl-1-(2
- Cheng, Yong,Xu, Hui-Jun,Sun, Jia-Feng,Li, Yi-Zhi,Chen, Xue-Tai,Xue, Zi-Ling
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- Quinoline-functionalized N-heterocyclic carbene complexes of iridium: Synthesis, structures and catalytic activities in transfer hydrogenation
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Iridium complexes containing quinoline-functionalized N-heterocyclic carbene (NHC) ligands have been synthesized by the transmetalation route from silver carbene precursors. The silver complexes undergo a facile reaction with [Ir(COD)Cl]2 (COD
- Sun, Jia-Feng,Chen, Fei,Dougan, Brenda A.,Xu, Hui-Jun,Cheng, Yong,Li, Yi-Zhi,Chen, Xue-Tai,Xue, Zi-Ling
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- In situ catalytic activities of 1,3-dialkyltetrahydropyrimidinium salts/[RuCl2(p-cymene)]2 system for transfer hydrogenation reactions
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Hydrogen-transfer reduction processes are attracting increasing interest from synthetic chemists in view of their operational simplicity. In the present study novel ruthenium carbene complexes were generated in situ and tested for their transfer hydrogena
- Oezge Oezcan, Emine,Mercan, Deniz,Guerbuez, Nevin,Cetinkaya, Engin,Cetinkaya, Bekir,Oezdemir, Ismail
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- Bis-N-heterocyclic carbene ruthenium(II) carbonyl complexes: Synthesis, structural characterization and catalytic activities in transfer hydrogenation of ketones
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In this contribution, the synthesis and characterization of eight ruthenium(II) carbonyl complexes supported by chelating alkane-bridged bis-N-heterocyclic carbene ligands are reported. The products obtained are analyzed using infrared and NMR spectroscop
- Cheng, Yong,Lu, Xiang-Yong,Xu, Hui-Jun,Li, Yi-Zhi,Chen, Xue-Tai,Xue, Zi-Ling
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- Applying Le Chatelier's Principle for a Highly Efficient Catalytic Transfer Hydrogenation with Ethanol as the Hydrogen Source
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While isopropanol or formic acid derivatives are mainly applied as hydrogen sources in catalytic transfer hydrogenation reactions, there are only a few reports on the use of primary alcohols. In the present communication we report that ecologically benign and cheap ethanol can be applied with a ruthenium(II) that is completely stable against moisture and oxygen. Catalytic transfer hydrogenation is an equilibrium reaction. Therefore, a rapid removal of acetic aldehyde being formed as the product of ethanol oxidation is the key for high conversions. The reaction shows a broad substrate scope and allows the hydrogenation of ketones, aldehydes and imines.
- Weingart, Pascal,Thiel, Werner R.
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- Hydrosilylation of Aldehydes and Ketones Catalyzed by a 2-Iminopyrrolyl Alkyl-Manganese(II) Complex
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A well-defined and very active single-component manganese(II) catalyst system for the hydrosilylation of aldehydes and ketones is presented. First, the reaction of 5-(2,4,6-iPr3C6H2)-2-[N-(2,6-iPr2C6H3)formimino]pyrrolyl potassium (KL) and [MnCl2(Py)2] afforded the binuclear 2-iminopyrrolyl manganese(II) pyridine chloride complex [Mn2{κ2N,N′-5-(2,4,6-iPr3C6H2)-NC4H2-2-C(H)═N(2,6-iPr2C6H3)}2(Py)2(μ-Cl)2] 1. Subsequently, the alkylation reaction of complex 1 with LiCH2SiMe3 afforded the respective (trimethylsilyl)methyl-Mn(II) complex [Mn{κ2N,N′-5-(2,4,6-iPr3C6H2)-NC4H2-2-C(H)═N(2,6-iPr2C6H3)}(Py)CH2SiMe3] 2 in a good yield. Complexes 1 and 2 were characterized by elemental analysis, 1H NMR spectroscopy, Evans' method, FTIR spectroscopy, and single-crystal X-ray diffraction. While the crystal structure of complex 1 has been identified as a binuclear entity, in which the Mn(II) centers present pentacoordinate coordination spheres, that of complex 2 corresponds to a monomer with a distorted tetrahedral coordination geometry. Complex 2 proved to be a very active precatalyst for the atom-economic hydrosilylation of several aldehydes and ketones under very mild conditions, with a maximum turnover frequency of 95 min-1, via a silyl-Mn(II) mechanistic route, as asserted by a combination of experimental and theoretical efforts, the respective silanes were cleanly converted to the respective alcoholic products in high yields.
- Cruz, Tiago F. C.,Veiros, Luís F.,Gomes, Pedro T.
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p. 1195 - 1206
(2022/01/11)
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- Half-Sandwich Nickel(II) NHC-Picolyl Complexes as Catalysts for the Hydrosilylation of Carbonyl Compounds: Evidence for NHC-Nickel Nanoparticles under Harsh Reaction Conditions
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The cationic [NiCp(Mes-NHC-CH2py]Br complex 2 a was prepared directly by the reaction of nickelocene with 1-(2-picolyl)-3-mesityl-imidazolium bromide (1), and its PF6? derivative 2 b, by subsequent salt metathesis. X-ray diffraction studies and Variable Temperature 1H NMR experiments run with 2 a and 2 b strongly suggest the bidentate coordination of the picolyl-functionalized carbene to the nickel both in the solid state and in solution in both cases. These data suggest the absence of hemilabile behavior of the latter, even in the presence of a coordinating anion. Both complexes show similar activity in aldehyde hydrosilylation, further implying the absence of hemilability of the picolyl-functionalized carbene, and effectively reduce a broad scope of aldehydes in the absence of additive under mild conditions. In the case of ketones, effective hydrosilylation is only observed in the presence of a catalytic amount of potassium t-butoxide at 100 °C. Dynamic light scattering, scanning transmission electron microscopy and X-ray photoelectron spectroscopy show evidence for the involvement of NHC-picolyl-Ni nanoparticles under these conditions.
- Ulm, Franck,Shahane, Saurabh,Truong-Phuoc, Lai,Romero, Thierry,Papaefthimiou, Vasiliki,Chessé, Matthieu,Chetcuti, Michael J.,Pham-Huu, Cuong,Michon, Christophe,Ritleng, Vincent
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supporting information
p. 3074 - 3082
(2021/08/03)
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- Benzimidazole fragment containing Mn-complex catalyzed hydrosilylation of ketones and nitriles
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The synthesis of a new bidentate (NN)–Mn(I) complex is reported and its catalytic activity towards the reduction of ketones and nitriles is studied. On comparing the reactivity of various other Mn(I) complexes supported by benzimidazole ligand, it was observed that the Mn(I) complexes bearing 6-methylpyridine and benzimidazole fragments exhibited the highest catalytic activity towards monohydrosilylation of ketones and dihydrosilylation of nitriles. Using this protocol, a wide range of ketones were selectively reduced to the corresponding silyl ethers. In case of unsaturated ketones, the chemoselective reduction of carbonyl group over olefinic bonds was observed. Additionally, selective dihydrosilylation of several nitriles were also achieved using this complex. Mechanistic investigations with radical scavengers suggested the involvement of radical species during the catalytic reaction. Stoichiometric reaction of the Mn(I) complex with phenylsilane revealed the formation of a new Mn(I) complex.
- Ganguli, Kasturi,Mandal, Adarsha,Sarkar, Bidisha,Kundu, Sabuj
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supporting information
(2020/08/13)
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- Palladium-Catalyzed Selective Reduction of Carbonyl Compounds
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Two new examples of structurally characterized β-diketiminate analogues i.e., conjugated bis-guanidinate (CBG) supported palladium(II) complexes, [LPdX]2; [L= {(ArHN)(ArN)–C=N–C=(NAr)(NHAr)}; Ar = 2,6-Et2-C6H3], X = Cl (1), Br (2) have been reported. The synthesis of complexes 1–2 was achieved by two methods. Method A involves deprotonation of LH by nBuLi followed by the treatment of LLi (insitu formed) with PdCl2 in THF, which afforded compound 1 in good yield (75 %). In Method B, the reaction between free LH and PdX2 (X = Cl or Br) in THF allowed the formation of complexes 1 (Yield 73 %) and 2 (Yield 52 %), respectively. Moreover, these complexes were characterized thoroughly by several spectroscopic techniques (1H, 13C NMR, UV/Vis, FT-IR, and HRMS), including single-crystal X-ray structural and elemental analyses. In addition, we tested the catalytic activity of these complexes 1–2 for the hydroboration of carbonyl compounds with pinacolborane (HBpin). We observed that compound 1 exhibits superior catalytic activity when compared to 2. Compound 1 efficiently catalyzes various aldehydes and ketones under solvent-free conditions. Furthermore, both inter- and intramolecular chemoselectivity hydroboration of aldehydes over other functionalities have been established.
- Sarkar, Nabin,Mahato, Mamata,Nembenna, Sharanappa
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p. 2295 - 2301
(2020/05/18)
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- Borohydride intermediates pave the way for magnesium-catalysed enantioselective ketone reduction
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A magnesium precatalyst for the highly enantioselective hydro-boration of CO bonds is reported. The mechanistic basis of the unprecedented selectivity of this transformation has been investi-gated experimentally by isolation of catalytic intermediates and theoretically by DFT calculations. The facile formation of a magnesium borohydride species is critical in overcoming competing pathways in the selectivity-determining insertion step.
- Vasilenko, Vladislav,Blasius, Clemens K.,Wadepohl, Hubert,Gade, Lutz H.
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supporting information
p. 1203 - 1206
(2020/02/04)
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- Bottleable NiCl2(dppe) as a catalyst for the Markovnikov-selective hydroboration of styrenes with bis(pinacolato)diboron
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Although transition-metal-catalysed hydroboration reactions of alkenes have been extensively studied, only three examples using Ni complexes have been reported so far. In this study, we have examined hydroboration reactions of alkenes using Ni/phosphine complexes. The commercially available and bottleable complex NiCl2(dppe) (dppe = 1,2-bis(diphenylphosphino)ethane) serves as a catalyst for the highly Markovnikov-selective hydroboration of styrene derivatives that affords the desired Markovnikov products in high yield.
- Hashimoto, Toru,Ishimaru, Toshiya,Shiota, Keisuke,Yamaguchi, Yoshitaka
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p. 11701 - 11704
(2020/10/20)
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- Phosphine-NHC Manganese Hydrogenation Catalyst Exhibiting a Non-Classical Metal-Ligand Cooperative H2 Activation Mode
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Deprotonation of the MnI NHC-phosphine complex fac-[MnBr(CO)3(κ2P,C-Ph2PCH2NHC)] (2) under a H2 atmosphere readily gives the hydride fac-[MnH(CO)3(κ2P,C-Ph2PCH2NHC)] (3) via the intermediacy of the highly reactive 18-e NHC-phosphinomethanide complex fac-[Mn(CO)3(κ3P,C,C-Ph2PCHNHC)] (6 a). DFT calculations revealed that the preferred reaction mechanism involves the unsaturated 16-e mangana-substituted phosphonium ylide complex fac-[Mn(CO)3(κ2P,C-Ph2P=CHNHC)] (6 b) as key intermediate able to activate H2 via a non-classical mode of metal-ligand cooperation implying a formal λ5-P–λ3-P phosphorus valence change. Complex 2 is shown to be one of the most efficient pre-catalysts for ketone hydrogenation in the MnI series reported to date (TON up to 6200).
- Buhaibeh, Ruqaya,Filippov, Oleg A.,Bruneau-Voisine, Antoine,Willot, Jérémy,Duhayon, Carine,Valyaev, Dmitry A.,Lugan, No?l,Canac, Yves,Sortais, Jean-Baptiste
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supporting information
p. 6727 - 6731
(2019/04/17)
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- Kinetic resolution of sterically hindered secondary alcohols catalyzed by aminophosphinite organocatalyst
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Kinetic resolution of secondary alcohols by benzoylation using a phosphinite derivative of (1S,2R)-1-amino-2-indanol as the catalyst was investigated. The aminophosphinite catalyst is effective for the kinetic resolution of aryl cycloalkyl carbinols with a small number of examples for organocatalytic kinetic resolution to achieve resolution with s = up to 44. Although the benzoylation of phenylalkanols proceeded with a low selectivity, 1-arylalkanols bearing at least one substituent at the ortho position on the benzene ring or a branched alkyl group on the carbinol carbon were resolved with acceptable selectivity.
- Hara, Nanami,Fujisawa, Shu,Fujita, Mizuki,Miyazawa, Mikako,Ochiai, Kazuma,Katsuda, Satoshi,Fujimoto, Tetsuya
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p. 296 - 302
(2017/12/11)
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- Asymmetric Hydrogenation of Polysubstituted Aromatic Ketones Catalyzed by the DIPSkewphos/PICA Derivative–Ruthenium(II) Complexes
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The DIPSkewphos/PICA derivative-Ru(II) complexes catalyzed asymmetric hydrogenation of significantly sterically hindered 2’,3’,4’,5’,6’-pentamethylacetophenone, which was not reduced with NaBH4 at 25 °C, with a substrate-to-catalyst molar ratio
- Utsumi, Noriyuki,Arai, Noriyoshi,Kawaguchi, Kei,Katayama, Takeaki,Yasuda, Toshihisa,Murata, Kunihiko,Ohkuma, Takeshi
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p. 3955 - 3959
(2018/08/01)
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- Constructing reactive Fe and Co complexes from isolated picolyl-functionalized N-heterocyclic carbenes
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We report the isolation of free picolyl-functionalized N-heterocyclic carbenes (NHCs), which serve as versatile precursors to access low coordinate iron and cobalt complexes. The reactivities of these new iron and cobalt complexes towards catalytic hydrosilylation of ketones have also been explored. For example, low loadings (0.05-1 mol%) of a four-coordinate iron complex bearing two deprotonated picolyl-NHC ligands can effect the fast catalytic reduction of ketones using the inexpensive industrial byproduct polymethylhydrosiloxane (PMHS) as the reductant at ambient temperature.
- Liang, Qiuming,Liu, Nina Jiabao,Song, Datong
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supporting information
p. 9889 - 9896
(2018/08/06)
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- Carbonyl and ester C-O bond hydrosilylation using κ4-diimine nickel catalysts
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The synthesis of alkylphosphine-substituted α-diimine (DI) ligands and their subsequent addition to Ni(COD)2 allowed for the preparation of (iPr2PPrDI)Ni and (tBu2PPrDI)Ni. The solid state structures of both compounds were found to feature a distorted tetrahedral geometry that is largely consistent with the reported structure of the diphenylphosphine-substituted variant, (Ph2PPr DI)Ni. To explore and optimize the synthetic utility of this catalyst class, all three compounds were screened for benzaldehyde hydrosilylation activity at 1.0 mol% loading over 3 h at 25 °C. Notably, (Ph2PPr DI)Ni was found to be the most efficient catalyst while phenyl silane was the most effective reductant. A broad scope of aldehydes and ketones were then hydrosilylated, and the silyl ether products were hydrolyzed to afford alcohols in good yield. When attempts were made to explore ester reduction, inefficient dihydrosilylation was noted for ethyl acetate and no reaction was observed for several additional substrates. However, when an equimolar solution of allyl acetate and phenyl silane was added to 1.0 mol% (Ph2PPr DI)Ni, complete ester C-O bond hydrosilylation was observed within 30 min at 25 °C to generate propylene and PhSi(OAc)3. The scope of this reaction was expanded to include six additional allyl esters, and under neat conditions, turnover frequencies of up to 990 h-1 were achieved. This activity is believed to be the highest reported for transition metal-catalyzed ester C-O bond hydrosilylation. Proposed mechanisms for (Ph2PPr DI)Ni-mediated carbonyl and allyl ester C-O bond hydrosilylation are also discussed.
- Rock, Christopher L.,Groy, Thomas L.,Trovitch, Ryan J.
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supporting information
p. 8807 - 8816
(2018/07/13)
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- Mechanism-Based Enantiodivergence in Manganese Reduction Catalysis: A Chiral Pincer Complex for the Highly Enantioselective Hydroboration of Ketones
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A manganese alkyl complex containing a chiral bis(oxazolinyl-methylidene)isoindoline pincer ligand is a precatalyst for a catalytic system of unprecedented activity and selectivity in the enantioselective hydroboration of ketones, thus producing preparatively useful chiral alcohols in excellent yields with up to greater than 99 % ee. It is applicable for both aryl alkyl and dialkyl ketone reduction under mild reaction conditions (TOF >450 h?1 at ?40 °C). The earth-abundant base-metal catalyst operates at very low catalyst loadings (as low as 0.1 mol %) and with a high level of functional-group tolerance. There is evidence for the existence of two distinct mechanistic pathways for manganese-catalyzed hydride transfer and their role for enantiocontrol in the selectivity-determining step is presented.
- Vasilenko, Vladislav,Blasius, Clemens K.,Wadepohl, Hubert,Gade, Lutz H.
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p. 8393 - 8397
(2017/07/11)
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- A Versatile Iridium(III) Metallacycle Catalyst for the Effective Hydrosilylation of Carbonyl and Carboxylic Acid Derivatives
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A versatile iridium(III) metallacycle catalysed rapidly and selectively the reduction of a large array of challenging esters and carboxylic acids as well as various ketones and aldehydes. The reactions proceeded in high yields at room temperature by hydrosilylation followed by desilylation. Although the reactions of various aldehydes and ketones resulted exclusively in alcohols, the hydrosilylation of esters led to alcohols or ethers, depending on the type of substrate. Regarding the carboxylic acids, again the nature of the reagent controlled the outcome of the hydrosilylation reaction, either alcohols or aldehydes being formed.
- Corre, Yann,Rysak, Vincent,Trivelli, Xavier,Agbossou-Niedercorn, Francine,Michon, Christophe
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supporting information
p. 4820 - 4826
(2017/09/07)
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- Hydrogenation of Carbonyl Derivatives with a Well-Defined Rhenium Precatalyst
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The first efficient and general rhenium-catalyzed hydrogenation of carbonyl derivatives was developed. The key to the success of the reaction was the use of a well-defined rhenium complex bearing a tridentate diphosphinoamino ligand as the catalyst (0.5 mol %) at 70 °C in the presence of H2 (30 bar). The mechanism of the reaction was investigated by DFT(PBE0-D3) calculations.
- Wei, Duo,Roisnel, Thierry,Darcel, Christophe,Clot, Eric,Sortais, Jean-Baptiste
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- Bis(silylenyl)-substituted ferrocene-stabilized η6-arene iron(0) complexes: Synthesis, structure and catalytic application
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Reaction of FeX2(thf)n (X = Cl n = 1.5, Br n = 2) with the chelating 1,1′-bis(silylenyl)-substituted ferrocene ligand SiFcSiA (Fc = ferrocendiyl, Si = PhC(NtBu)2Si:) furnishes the corresponding dihalido Fe(ii) complexes [(SiFcSi)FeX2] (X = Cl, 1 and X = Br, 2) in high yields. Reduction of the latter with an excess of KC8 in the presence of benzene and toluene leads to the unprecedented bis(silylene) stabilized Fe0 complexes [(SiFcSi)Fe-η6(C6H6)] 3 and [(SiFcSi)Fe-η6(C7H8)] 4, respectively. The 57Fe M?ssbauer spectrum of 3 at 13 K exhibits parameters (σ = 0.3676 mm s-1; ΔEQ = 1.334 mm s-1) which are consistent with the presence of a pentacoordinated Fe0 atom in a pseudo trigonal-bipyramidal coordination environment, with two dative Si→Fe bonds and three coordination sites occupied by the η6-coordinated arene ligand. Results from DFT calculations, 57Fe M?ssbauer parameters and the diamagnetic NMR spectra confirm the redox-innocent nature of these ligands and the zero oxidation state of the iron center. The catalytic ability of 3 was investigated with respect to ketone hydrogenation. In all cases, good to excellent yields to the corresponding alcohols were obtained at 50 °C and 50 bar H2 pressure. Electron-donating as well as -withdrawing substituents were tolerated with excellent to good yields. Conversions of bulkier ketones and unactivated aliphatic ketones lead merely to moderate yields. This represents the first example of a silylene-iron metal complex which has been utilized as a highly active precatalyst in the hydrogenation of ketones. The results underline the powerful ability of chelating bis(N-heterocyclic silylene) ligands acting as strong σ-donor ligands in stabilizing a new generation of low-valent, electron-rich transition metal complexes for catalytic transformations.
- Luecke, Marcel-Philip,Porwal, Digvijay,Kostenko, Arseni,Zhou, Yu-Peng,Yao, Shenglai,Keck, Matthias,Limberg, Christian,Oestreich, Martin,Driess, Matthias
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supporting information
p. 16412 - 16418
(2017/12/15)
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- Tris(cyclopentadienyl)lanthanide Complexes as Catalysts for Hydroboration Reaction toward Aldehydes and Ketones
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It was found that homoleptic cyclopentadienyl lanthanide complexes Cp3Ln (Ln = Y (1), Yb (2), Sm (3), Nd (4), La (5), Cp = cyclopentadienyl) can be employed as excellent catalysts for the hydroboration of various aldehydes and ketones toward pinacolborane. These robust lanthanide catalysts exhibited high reactivity with low catalyst loadings (0.01-1 mol %) under mild conditions and good functional group tolerability. These complexes also demonstrated uniquely carbonyl-selective hydroboration in the presence of alkenes and alkynes.
- Chen, Sufang,Yan, Dandan,Xue, Mingqiang,Hong, Yubiao,Yao, Yingming,Shen, Qi
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supporting information
p. 3382 - 3385
(2017/07/13)
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- 1-Substituted-imidazo[1,5-a]pyridin-3-ylidenes as highly efficient ligands for Rh- and Ir-catalyzed transfer hydrogenation of carbonyl compounds
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The transfer hydrogenation of carbonyl compounds catalyzed by Rh and Ir complexes bearing 1-substituted-imidazo[1,5-a]pyridin-3-ylidene ligands is reported. These catalysts, especially the Rh catalyst, showed high efficiency for the reaction. Comparison o
- Koto, Yuma,Shibahara, Fumitoshi,Murai, Toshiaki
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supporting information
p. 1327 - 1329
(2016/11/09)
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- The Asymmetric Piers Hydrosilylation
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An axially chiral, cyclic borane decorated with just one C6F5 group at the boron atom promotes the highly enantioselective hydrosilylation of acetophenone derivatives without assistance of an additional Lewis base (up to 99% ee). The reaction is an unprecedented asymmetric variant of Piers' B(C6F5)3-catalyzed carbonyl hydrosilylation. The steric congestion imparted by the 3,3′-disubstituted binaphthyl backbone of the borane catalyst as well as the use of reactive trihydrosilanes as reducing agents are keys to success.
- Süsse, Lars,Hermeke, Julia,Oestreich, Martin
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supporting information
p. 6940 - 6943
(2016/07/06)
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- Catalytic enantioselective acyl transfer: the case for 4-PPY with a C-3 carboxamide peptide auxiliary based on synthesis and modelling studies
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A series of 4-pyrrolidinopyridine (4-PPY) C-3 carboxamides containing peptide-based side chains have been synthesised and evaluated in the kinetic resolution of a small library of chiral benzylic secondary alcohols. A key design element was the incorporation of a tryptophan residue in the peptide side chain for promoting π-stacking between peptide side chain and the pyridinium ring of the N-acyl intermediate, in which modelling was used as a structure-based guiding tool. Together, a catalyst containing a LeuTrp-N-Boc side chain (catalyst 8) was identified that achieved s-values up to and in slight excess of 10. A transition-state model based on the modelling is proposed to explain the origin of enantioselectivity. This study establishes the usefulness of modelling as a structure-based guiding tool for enantioselectivity optimization as well as the potential for developing scalable peptide-based DMAP-type catalysts for large-scale resolution work.
- Cozett, Rudy E.,Venter, Gerhard A.,Gokada, Maheswara Rao,Hunter, Roger
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supporting information
p. 10914 - 10925
(2016/12/06)
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- Kinetic resolution of secondary carbinols by a chiral N,N-4-dimethylaminopyridine derivative containing a 1,1′-binaphthyl unit: Hydrogen bonding affects catalytic activity and enantioselectivity
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We developed an acylative kinetic resolution of secondary carbinols using a binaphthyl-based N,N-4-dimethylaminopyridine (DMAP) derivative 1d with tert-Alcohol substituents. The reaction proceeded with a wide range of carbinols with moderate to high selectivity (s) (up to s = 79.5). Kinetic studies revealed that catalyst 1d was more catalytically active than the corresponding bis-methyl ether 1d′ or DMAP. Hydrogen bonding between tert-Alcohols of the catalyst and secondary carbinols was responsible for the enhanced reaction rate and high enantioselectivity.
- Fujii, Kazuki,Mitsudo, Koichi,Mandai, Hiroki,Suga, Seiji
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p. 1081 - 1092
(2016/10/11)
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- PRODUCTION METHOD OF OPTICALLY ACTIVE SECONDARY ALCOHOL
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PROBLEM TO BE SOLVED: To provide a chemical catalytic method allowing efficient production of a corresponding optically active secondary alcohol from an aromatic ketone having a substituent at each of two β-positions in an aromatic ring to the carbonyl site, so that both enantiomers can be separately made. SOLUTION: A production method of optically active secondary alcohol is characterized by reacting a ketone compound such as acetophenone derivatives with hydrogen in the presence of a ruthenium complex catalyst having an optically active diphosphine ligand. COPYRIGHT: (C)2015,JPO&INPIT
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Paragraph 0132; 0140; 0141; 0144; 0151
(2016/11/14)
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- Ruthenium Catalyzed Selective Hydroboration of Carbonyl Compounds
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Using the [Ru(p-cymene)Cl2]2 (1) complex, catalytic hydroboration of aldehydes and ketones with pinacolborane under neat and mild conditions is reported. At rt, chemoselective hydroboration of aldehydes over the ketones is also attained. Mechanistic studies confirmed the immediate formation of monohydride bridged dinuclear complex [{(μ6-p-cymene)RuCl}2(μ-H-μ-Cl)] (1b) from the reaction of 1 with pinacolborane, which catalyzed the highly efficient hydroboration reactions. The catalytic cycle containing mononuclear Ru-H species and intramolecular 1,3-hydride transfer is postulated.
- Kaithal, Akash,Chatterjee, Basujit,Gunanathan, Chidambaram
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supporting information
p. 4790 - 4793
(2015/10/12)
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- Catalytic activity of Ru/tetrahydropyrimidinium salts system for transfer hydrogenation reactions
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New 1,3-dialkyltetrahydropyrimidinium salts as NHC precursors have been synthesized and characterized. The in situ prepared three-component 1,3-dialkyltetrahydropyrimidinium salts/[RuCl2(p-cymene)]2 and KOH catalyzes quantitatively t
- Karaca, Emine ?zge,Gürbüz, Nevin,Arslan, Hakan,Vanderveer, Don,?zdemir, Ismail
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p. 475 - 480
(2015/06/30)
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- Synthesis, characterization and catalytic, cytotoxic and antimicrobial activities of two novel cyclotriphosphazene-based multisite ligands and their Ru(II) complexes
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Two novel cyclotriphosphazene ligands (2 and 3) bearing 3-oxypyridine groups and their corresponding Ru(II) complexes (4 and 5) were synthesized and their structures were characterized using Fourier transform infrared, 1H NMR and 31P
- irali, Digdem Erdener,Uyar, Zafer,Koyuncu, Ismail,Haciolu, Nurcihan
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p. 536 - 542
(2015/08/04)
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- Iron-catalyzed asymmetric hydrosilylation of ketones
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A series of iron complexes of chiral iminopyridine-oxazoline (IPO) ligands have been synthesized. The most sterically hindered iron catalyst exhibits excellent activity (up to 99% yield) and high enantioselectivity (up to 93% ee) in asymmetric hydrosilylation of aryl ketones. This journal is
- Zuo, Ziqing,Zhang, Lei,Leng, Xuebing,Huang, Zheng
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supporting information
p. 5073 - 5076
(2015/03/30)
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- Colloidal nickel(0)-carboxymethyl cellulose particles: A biopolymer-inorganic catalyst for hydrogenation of nitro-aromatics and carbonyl compounds
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Colloidal solution of nickel(0) in carboxymethyl cellulose showed good catalytic efficiency in hydrogenation of aromatic nitro compounds, as well as aliphatic and aromatic ketones in aqueous medium yielding the respective aromatic amines and alcohols in excellent yield along with moderate to good reusability of the catalyst. The catalyst was isolated and characterized by powder XRD, EDX, SEM and TEM studies. The active phase of the catalyst consists of nickel nanoparticles entrapped in carboxymethyl cellulose (Col-Ni-CMC Nps). The ecofriendly synthesis was performed in water at room temperature by NaBH4 reduction of nickel chloride in the presence of sodium carboxymethyl cellulose (CMC).
- Harrad, Mohamed Anouar,Boualy, Brahim,El Firdoussi, Larbi,Mehdi, Ahmad,Santi, Claudio,Giovagnoli, Stefano,Nocchetti, Morena,Ait Ali, Mustapha
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- Catalytic hydrosilylation of ketones using a Co/Zr heterobimetallic complex: Evidence for an unusual mechanism involving ketyl radicals
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The tris(phosphinoamide)-linked heterobimetallic Co/Zr complex (THF)Zr(MesNPiPr2)3CoN2 (1) has been investigated as a catalyst for the hydrosilylation of ketones with PhSiH 3. Catalytic activity superior to monometallic Co or Zr analogues has been observed, demonstrating the importance of cooperative reactivity between Co and Zr. Upon examining stoichiometric reactions, complex 1 was found to be unreactive toward PhSiH3, implying that the mechanism diverges from the typical Chalk-Harrod-type hydrosilylation pathway. In contrast, 1 reacts readily with ketones, and in the case of benzophenone, a radical coupling product [(Ph2CO)Zr(MesNPiPr2) 3CoN2]2 (3) was isolated, implying the intermediacy of a Zr-bound ketyl radical fragment. A radical-based hydrosilylation mechanism is proposed involving hydrogen atom transfer from PhSiH3 to the Zr-bound ketyl-radical.
- Zhou, Wen,Marquard, Seth L.,Bezpalko, Mark W.,Foxman, Bruce M.,Thomas, Christine M.
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p. 1766 - 1772
(2013/05/08)
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- A convenient nickel-catalysed hydrosilylation of carbonyl derivatives
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Hydrosilylation of aldehydes and ketones catalysed by nickel acetate and tricyclohexylphosphine as the catalytic system was demonstrated using polymethylhydrosiloxane as a cheap reducing reagent. The Royal Society of Chemistry 2013.
- Zheng, Jianxia,Darcel, Christophe,Sortais, Jean-Baptiste
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- Asymmetric hydrogenation of tert-alkyl ketones: DMSO effect in unification of stereoisomeric ruthenium complexes
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Face off: The ruthenium complexes of a new axially chiral PNNligand (L) are highly efficient in the presence of dimethylsulfoxide (DMSO) for hydrogenation of both functionalized and unfunctionalized tert-alkyl ketones. DMSO is thought to narrow down the many possible complex stereoisomers into a single facial L/Ru complex, thus enhancing the reactivity, selectivity, and productivity. Copyright
- Yamamura, Tomoya,Nakatsuka, Hiroshi,Tanaka, Shinji,Kitamura, Masato
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supporting information
p. 9313 - 9315
(2013/09/12)
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- Enhancement of enantioselectivity by alcohol additives in asymmetric hydrogenation with bis(oxazolinyl)phenyl ruthenium catalysts
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Bis(oxazolinyl)phenyl ruthenium(ii) complexes were found to catalyze asymmetric hydrogenation of ketones, in which chiral bulky alcohol additives showed significant enhancement of enantioselectivity even in protic solvents. The Royal Society of Chemistry 2012.
- Ito, Jun-Ichi,Teshima, Tomoki,Nishiyama, Hisao
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supporting information; experimental part
p. 1105 - 1107
(2012/03/08)
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- Synthesis and catalytic activity of ruthenium(II) complexes containing pyridine-based tridentate triamines (′ NNN ′) and pyridine carboxylate ligands (NO )
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The reaction of [(p-cymene)RuCl2]2 with K[NO a-b] (NO- = 2-picolinate, a or 2-quinaldinate, b) gave neutral [(p-cymene)RuCl(NOa-b)] (1a-b), complexes which were treated with pyridine-based meridional triamine ligands (′NNN ′) to create complexes of the type [RuCl(NOa-b) (′NNN′)] (2a: ′N = Nd, NOa- = 2-picolinato; 2b: ′N = Nd, NOb- = 2-quinaldinato; 3a: ′N = Nb, NOa- = 2-picolinato; 3b: ′N = Nb, NOb- = 2-quinaldinato; 4a: ′N = Np, NOa- = 2-picolinato; 4b: ′N = Np, NOb- = 2-quinaldinato). The new compounds were characterized by elemental analysis, IR and NMR spectroscopy and, 1b was studied by single crystal X-ray diffraction. The complexes 1-4 have been employed as catalysts for the transfer hydrogenation (TH) of acetophenone derivatives to secondary alcohols in the presence of KOH using 2-propanol as a hydrogen source at 82 °C. The highest catalytic activity was obtained with 3a.
- Dayan, Osman,?zdemir, Namik,?erbetci, Zafer,Din?er, Muharrem,?etinkaya, Bekir,Büyükgüng?r, Orhan
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p. 246 - 253
(2013/01/13)
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- Magnesium-catalysed hydroboration of aldehydes and ketones
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The heteroleptic magnesium alkyl complex [CH{C(Me)NAr}2Mg nBu] (Ar = 2,6-iPr2C6H3) is reported as a highly efficient pre-catalyst for the hydroboration of aldehydes and ketones with pinacolborane. The Royal Society of Chemistry 2012.
- Arrowsmith, Merle,Hadlington, Terrance J.,Hill, Michael S.,Kociok-Koehn, Gabriele
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supporting information; experimental part
p. 4567 - 4569
(2012/06/05)
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- Hydrosilylation of aldehydes and ketones catalyzed by an n-heterocyclic carbene-nickel hydride complex under mild onditions
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Half-sandwich N-heterocyclic carbene (NHC)-nickel complexes of the general formula [NiACHTUNGTRENUNG(NHC)ClCp?] (Cp?= Cp, Cp*) efficiently catalyze the hydrosilylation of aldehydes and ketones at room temperature in the presence of a catalytic amount of sodium triethylborohydride and thus join the fairly exclusive club of well-defined nickel(II) catalyst precursors for the hydrosilylation of carbonyl functionalities. Of notable interest is the isolation of an intermediate nickel hydride complex that proved to be the real catalyst precursor.
- Bheeter, Linus P.,Henrion, Mickael,Brelot, Lydia,Darcel, Christophe,Chetcuti, Michael J.,Sortais, Jean-Baptiste,Ritleng, Vincent
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supporting information
p. 2619 - 2624
(2013/01/15)
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- Ruthenium phenylindenyl complex as an efficient transfer hydrogenation catalyst
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An efficient and green protocol for the transfer hydrogenation of carbonyl and imine compounds is presented. The transformations are catalysed by the inexpensive and easily synthesised complex [RuCl(PPh3)(3- phenylindenyl)]. Its catalytic activity was compared to that of the most commonly encountered ruthenium complexes in transfer hydrogenation reactions involving several protypical substrates. Copyright
- Manzini, Simone,Blanco, Cesar A. Urbina,Nolan, Steven P.
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supporting information
p. 3036 - 3044
(2013/01/15)
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- Preparation of a series of Ru(ii) complexes with N-heterocyclic carbene ligands for the catalytic transfer hydrogenation of aromatic ketones
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The reaction of [RuCl2(p-cymene]2 with Ag-N-heterocyclic carbene (NHC) complexes yields a series of [(p-cymene)Ru(NHC)] complexes (2a-f). All synthesised compounds were characterized by elemental analysis, NMR spectroscopy and the mo
- Guerbuez, Nevin,Oezcan, Emine Oezge,Oezdemir, Ismail,Cetinkaya, Bekir,Sahin, Onur,Bueyuekguengoer, Orhan
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scheme or table
p. 2330 - 2339
(2012/03/22)
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- Kinetic resolution of secondary alcohols using amidine-based catalysts
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Kinetic resolution of racemic alcohols has been traditionally achieved via enzymatic enantioselective esterification and ester hydrolysis. However, there has long been considerable interest in devising nonenzymatic alternative methods for this transformation. Amidine-based catalysts (ABCs), a new class of enantioselective acyl transfer catalysts developed in our group, have demonstrated, inter alia, high efficacy in the kinetic resolution of benzylic, allylic, and propargylic secondary alcohols and 2-substituted cycloalkanols, and thus provide a viable alternative to enzymes.
- Li, Ximin,Jiang, Hui,Uffman, Eric W.,Guo, Lei,Zhang, Yuhua,Yang, Xing,Birman, Vladimir B.
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experimental part
p. 1722 - 1737
(2012/04/04)
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- Iron dihydride complex as the pre-catalyst for efficient hydrosilylation of aldehydes and ketones under visible light activation
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A general and efficient hydrosilylation of aldehydes and ketones into the corresponding alcohols using the well-defined bis(diphenylphosphinoethane)iron dihydride complex as the pre-catalyst is reported using polymethylhydrosiloxane (PMHS) as the reducing silylating agent and sodium tetraethoxyborate [NaB(OEt)4] as a co-catalyst under visible light irradiation. The low catalyst loadings (0.1-1 mol%), the amount of economical hydride source, PMHS and the unconventional way of activation of the pre-catalyst make this new approach attractive.
- Castro, Luis C. Misal,Bezier, David,Sortais, Jean-Baptiste,Darcel, Christophe
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supporting information; experimental part
p. 1279 - 1284
(2011/06/26)
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- Synthesis of ruthenium(II) complexes containing tridentate triamine (′NNN′) and bidentate diamine ligands (NN′): As catalysts for transfer hydrogenation of ketones
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A series of neutral and cationic Ru(II) complexes (1-10), bearing pyridine-based tridentate (′NNN′), pyridine-based bidentate (NN′), and mixed ′NNN′ + NN′ ligands, were synthesized by starting from [RuCl 2(DMSO)4] and [RuCl2(p-cymene)]2 precursors. Solid-state structures of mixed-ligand complexes 9 and 10 were determined by single-crystal X-ray diffraction. Both complexes are unusual in that NN′ ligands were spontaneously oxidized in air under base-free conditions to give imine-amine bidentate ligands upon replacement of p-cymene by meridional ′NNN′. The complexes 1-10 were screened for transfer hydrogenation (TH) of aryl ketones with 2-propanol. The highest catalytic activity was obtained with the complexes containing tridentate ′NNN′ and 7, which contain nonsulfonated 2-(aminomethyl)pyridine. However, for complexes 6a-c, containing p-cymene (a facial tridentate ligand), a slower reaction rate was observed.
- Guennaz, Salih,Oezdemir, Namk,Dayan, Serkan,Dayan, Osman,Cetinkaya, Bekir
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experimental part
p. 4165 - 4173
(2011/10/03)
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- Highly enantioselective bioreduction of prochiral ketones by stem and germinated plant of Brassica oleracea variety italica
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An eco-friendly and environmentally benign asymmetric reduction of a broad range of prochiral ketones employing Brassica oleracea variety italica (stems and germinated plant) as a novel biocatalyst was developed. It was found that B. oleracea variety italica could be used effectively for enantioselective bioreduction in aqueous medium with moderate to excellent chemical yield and enantiomeric excess (ee). This process is more efficient and generates less waste than conventional chemical reagents or microorganisms. Both R- and S-configurations were obtained by these asymmetric reactions. The best ee were achieved for pyridine derivatives (92-99%). The ee in germinated plant reactions were significantly higher than those of stem reactions. The low cost and the easy availability of these biocatalysts suggest their possible use for large scale preparations of important chiral alcohols.
- Mohammadi, Mehdi,Yousefi, Maryam,Habibi, Zohreh
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experimental part
p. 328 - 336
(2012/03/11)
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- Design, synthesis, and evaluation of a helicenoidal DMAP lewis base catalyst
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The design, synthesis, and study of a helical dialkylaminopyridine Lewis base catalyst is reported. Helical DMAP analogue 4 is based upon a helicenoid structure and displays good to excellent levels of selectivity (S ≤ 116) in the kinetic resolution of chiral secondary alcohols. Catalyst 4 displays excellent reactivity with exceptionally low loadings of 0.05 mol % effecting practical levels of selectivity in kinetic resolutions.(Figure Presented)
- Crittall, Matthew R.,Rzepa, Henry S.,Carbery, David R.
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supporting information; experimental part
p. 1250 - 1253
(2011/04/25)
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- Chemo-and stereoselective iron-catalyzed hydrosilylation of ketones
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The reduction of ketones with polymethylhydrosiloxane (PMHS) gives the corresponding alcohols in good to excellent yield applying iron-based catalyst systems. In the case of prochiral ketones, the use of Fe(OAc) 2/(S,S)-Me-DuPhos leads to high enantioselectivity up to 99% ee. The reaction proceeds in the presence of several functional groups such as esters, halides as well as conjugated double bonds, with high chemoselectivity. The advantage of this protocol is that the reaction requires no activating agents or additives.
- Addis, Daniele,Shaikh, Nadim,Zhou, Shaolin,Das, Shoubhik,Junge, Kathrin,Beller, Matthius
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experimental part
p. 1687 - 1691
(2011/08/05)
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- Transfer hydrogenation of ketones by ruthenium complexes bearing benzimidazol-2-ylidene ligands
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A series of benzimidazolium ligand precursors were metalated with [RuCl2(p-cymene)]2 to give ruthenium(II) N-heterocyclic carbene complexes. All compounds were fully characterized by elemental analyses, 1H NMR, 13/su
- Guerbue, Nevin,Yasar, Sedat,Ozean, Emine Ozge,Ozdemir, Ismail,Cetinkaya, Bekir
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experimental part
p. 3051 - 3056
(2011/01/07)
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