- Maleates from diazoacetates and dilactones from head-to-head dimerisation of alkenyl diazoacetates using Grubbs' 2nd-generation ruthenium carbene catalyst
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Grubbs' 2nd-generation ruthenium carbene catalyst homocouples diazoacetates to maleates and also catalyses head-to-head dimerisation of alkenyl diazoacetates giving dienyl dilactones. The Royal Society of Chemistry 2005.
- Hodgson, David M.,Angrish, Deepshikha
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- Catalytic Formation of Aziridines from Imines and Diazoacetates
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A catalytic method for the preparation of aziridines from imines and diazoacetate is developed using copper complexes as catalyst; the synthetic, diastereo- and enantio-selective scope of the reaction are presented.
- Rasmussen, Kaare G.,Joergensen, Karl Anker
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- Cyclopropanation of alkenes with ethyl diazoacetate catalysed by ruthenium porphyrin complexes
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Ruthenium porphyrin complexes are active catalysts for the cyclopropanation of styrene derivatives by ethyl diazoacetate with good to very good diastereoselectivity; moderate enantiomeric excesses (34%) are observed using a chiral porphyrin as catalyst.
- Galardon, Erwan,Le Maux, Paul,Simonneaux, Gerard
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- Confinement of Fe-Al-PMOF catalytic sites favours the formation of pyrazoline from ethyl diazoacetate with an unusual sharp increase of selectivity upon recycling
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The catalytic properties of a chemically stable iron porphyrin MOF were evaluated in a reaction with ethyl diazoacetate. In contrast to its homogeneous counterpart, an Fe-porphyrin-MOF features a different reaction pathway leading to the formation of pyrazoline due to the confinement of catalytic sites within the MOF network. Unexpectedly, a sharp increase of the selectivity from 35% (run 1) to 86% (run 5) occurs upon catalyst recycling.
- Abeykoon, Brian,Devic, Thomas,Grenèche, Jean-Marc,Fateeva, Alexandra,Sorokin, Alexander B.
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- Synthesis and Characterization of Germanium, Tin, Phosphorus, Iron, and Rhodium Complexes of Tris(pentafluorophenyl)corrole, and the Utilization of the Iron and Rhodium Corroles as Cyclopropanation Catalysts
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The germanium(IV), tin(IV), and phosphorus(V) complexes of tris(pentafluorophenyl)corrole were prepared and investigated by electrochemistry for elucidation of the electrochemical HOMO-LUMO gap of the corrole and the spectroscopic characteristics of the corrole ? radical cation. This information was found to be highly valuable for assigning the oxidation states in the various iron corroles that were prepared. Two iron corroles and the rhodium(I) complex of an N-substituted corrole were fully characterized by X-ray crystallography and all the transition metal corroles were examined as cyclopropanation catalysts. All iron (except the NO-ligated) and rhodium corroles are excellent catalysts for Cyclopropanation of styrene, with the latter displaying superior selectivities. An investigation of the effect of the oxidation state of the metal and its ligands leads to the conclusion that for iron corroles the catalytically active form is iron(III), while all accesible oxidation states of rhodium are active.
- Simkhovich, Liliya,Mahammed, Atif,Goldberg, Israel,Gross, Zeev
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- Mechanochemical defect engineering of HKUST-1 and impact of the resulting defects on carbon dioxide sorption and catalytic cyclopropanation
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Metal-organic frameworks (MOFs) are recognized as ideal candidates for many applications such as gas sorption and catalysis. For a long time the properties of these materials were thought to essentially arise from their well-defined crystal structures. It is only recently that the importance of structural defects for the properties of MOFs has been evidenced. In this work, salt-assisted and liquid-assisted grinding were used to introduce defects in a copper-based MOF, namely HKUST-1. Different milling times and post-synthetic treatments with alcohols allow introduction of defects in the form of free carboxylic acid groups or reduced copper(i) sites. The nature and the amount of defects were evaluated by spectroscopic methods (FTIR, XPS) as well as TGA and NH3temperature-programmed desorption experiments. The negative impact of free -COOH groups on the catalytic cyclopropanation reaction of ethyl diazoacetate with styrene, as well as on the gravimetric CO2sorption capacities of the materials, was demonstrated. The improvement of the catalytic activity of carboxylic acid containing materials by the presence of CuIsites was also evidenced.
- Barozzino-Consiglio, Gabriella,Filinchuk, Yaroslav,Grégoire, Nicolas,Hermans, Sophie,Steenhaut, Timothy
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- Carbenoid transfer in competing reactions catalyzed by ruthenium complexes
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Aiming at improving catalyst activity, ten ruthenium promoters have been investigated in carbenoid transfer from ethyl diazoacetate to styrene as a model substrate. Optimal selectivity in cyclopropanation has been attained with the new NHC-Ru complex 10, as well as with the Fischer carbene 7. The surprising non-metathetical behavior of the Grubbs' first-generation catalyst in this multifaceted process is highlighted. Copyright
- Dragutan, Ileana,Dragutan, Valerian,Verpoort, Francis
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- Catalytic transformations of diazo compounds promoted by platinum(0) and dicationic platinum(II) complexes
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9-Diazofluorene (DAF) is decomposed either stoichiometrically or catalytically in the presence of the platinum(0) complex [Pt(C2H4)(PPh3)2] to give difluoren-9-ylidene-hydrazine in high yield. Under analogous reaction conditions, diphenyldiazomethane gives mostly the azine, Ph2CNNCPh2, while ethyl diazoacetate (EDA) affords, in low yield, a mixture of diethyl fumarate and maleate in approximately 10:1 molar ratio. The cyclopropanation of styrene with EDA is catalyzed by a series of dicationic complexes of the type [PtL2(NCCH3)2][Y]2 (L2=2PPh3, Ph2PCH=CHPPh2, Ph2PCH2CH2PPh2; Y=BF4, CF3SO3) in 1,2-dichloroethane at 60 °C for 24 h. DAF and EDA undergo insertion reactions into the OH bond of alcohols ROH (R=Me, Et, t-Bu, CH2CHCH2, Ph) at 25 °C in CH2Cl2-ROH (DAF or EDA-ROH molar ratio 1/20) in the presence of 1% mol of several dicationic platinum(II) complexes to give the corresponding ethers in excellent yields.
- Bertani, Roberta,Biasiolo, Monica,Darini, Katia,Michelin, Rino A,Mozzon, Mirto,Visentin, Fabiano,Zanotto, Livio
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- Continuous flow asymmetric cyclopropanation reactions using Cu(i) complexes of Pc-L* ligands supported on silica as catalysts with carbon dioxide as a carrier
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Continuous flow heterogeneous asymmetric cyclopropanations catalysed by supported hydrogen-bonded (SHB) chiral copper(i) complexes of pyridine containing tetraazamacrocyclic ligands Pc-L* using CO2 as a transport vector are described. The catalytic system showed high stability and good recyclability without loss of activity for at least 24 h in CO2 and catalyst turnover numbers up to 440 were obtained with excellent conversion (up to 99%) and high selectivity (up to 88%). No leaching of copper was observed. Cyclopropane products from both aromatic and aliphatic olefins were obtained in good yields with enantiomeric excesses up to 72%. This journal is the Partner Organisations 2014.
- Castano, Brunilde,Gallo, Emma,Cole-Hamilton, David J.,Dal Santo, Vladimiro,Psaro, Rinaldo,Caselli, Alessandro
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- Cobalt carbaporphyrin-catalyzed cyclopropanation
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Cobalt complexes of N-confused porphyrins and benziphthalocyanine, which both feature organometallic bonds at the macrocycle cores, catalyze the cyclopropanation of styrene with a higher trans-selectivity than the corresponding porphyrin and phthalocyanine complexes. The Royal Society of Chemistry 2011.
- Fields, Kimberly B.,Engle, James T.,Sripothongnak, Saovalak,Kim, Chungsik,Zhang, X. Peter,Ziegler, Christopher J.
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- Hydrogenation of Alkynes with Water and a Titanium(II) Complex
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μ-Oxobis(dicyclopentadienyl)(alkenyl)titanium(IV) complexes were prepared from (η5-C5H5)2Ti(CO)2 and alkyne in the presence of water and gave the corresponding cis-olefins.
- Demerseman, Bernard,Dixneuf, Pierre H.
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- Iron porphyrins catalyze the synthesis of non-protected amino acid esters from ammonia and diazoacetates
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Iron complexes of porphyrins (and corroles to a lesser extent) are the first catalysts to utilize ammonia for the synthesis of N-free amino acid esters. The Royal Society of Chemistry 2006.
- Aviv, Iris,Gross, Zeev
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- Rhodium-mediated stereoselective polymerization of "carbenes"
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Unprecedented rhodium-catalyzed stereoselective polymerization of "carbenes" from ethyl diazoacetate (EDA) to give high molecular mass poly(ethyl 2-ylidene-acetate) is described. The mononuclear, neutral [(N,O-ligand)M1(cod)] (M = Rh, Ir) catalytic precursors for this reaction are characterized by (among others) single-crystal X-ray diffraction. These species mediate formation of a new type of polymers from EDA: carbon-chain polymers functionalized with a polar substituent at each carbon of the polymer backbone. The polymers are obtained as white powders with surprisingly sharp NMR resonances. Solution and solid state NMR data for these new polymers reveal a highly stereoregular polymer, with a high degree of crystallinity. The polymer is likely syndiotactic. Material properties are very different from those of atactic poly(diethyl fumarate) polymer obtained by radical polymerization of diethyl fumarate. Other diazoacetates are also polymerized. Further studies are underway to reveal possible applications of these new materials.
- Hetterscheid, Dennis G. H.,Hendriksen, Coen,Dzik, Wojciech I.,Smits, Jan M. M.,Van Eck, Ernst R. H.,Rowan, Alan E.,Busico, Vincenzo,Vacatello, Michele,Van Axel Castelli, Valeria,Segre, Annalaura,Jellema, Erica,Bloemberg, Tom G.,De Bruin, Bas
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- Monomeric Rhodium(II) Catalysts for the Preparation of Aziridines and Enantioselective Formation of Cyclopropanes from Ethyl Diazoacetate at Room Temperature
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A family of bis(oxazoline) complexes of coordinatively unsaturated monomeric rhodium (II) (2a,b,3a,b) are described. These complexes serve as catalysts for cyclopropanation of olefins by ethyl diazoacetate, giving excellent yields (66-84%). The reaction shows an unusual preference for formation of the cis isomers. Catalytic aziridination of N-aryl imines with diazoacetate is also described.
- Krumper,Gerisch,Suh,Bergman,Tilley
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- Highly enantioselective ruthenium/PNNP-catalyzed imine aziridination: Evidence of carbene transfer from a diazoester complex
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The ruthenium/PNNP complexes [RuCl(Et2O)(PNNP)]Y (Y = PF 6, 4PF6; BF4, 4BF4; or SbF 6, 4SbF6) (10 mol %) catalyze the enantioselective aziridination of imines with ethyl diazoacetate (EDA) as carbene source (PNNP = (1S,2S)-N,N′-bis[o-(diphenylphosphino)benzylidene]cyclohexane-1,2-diamine) . The highest enantioselectivity was obtained with 4SbF6, which aziridinated N-benzylidene-1,1-diphenylmethanamine (5a) to cis-ethyl 1-benzhydryl-3-phenylaziridine-2-carboxylate (cis-6a) with 93% ee at 0 C. To the best of our knowledge, this is the highest enantioselectivity ever obtained in transition metal-catalyzed asymmetric aziridination. Aziridine yields were overall moderate to low (up to 33% isolated yield of the cis isomer) because of the competitive formation of diethyl maleate (7). The scope of the catalyst was studied with p- and m-substituted imines. NMR spectroscopic studies with 13C- and 15N-labeled EDA indicate that aziridine 6a is formed by carbene transfer from an EDA complex, [RuCl(EDA)(PNNP)]PF6 (8), to the imine. The observation of a dinitrogen complex (9) gives further support to this mechanism. The EDA adduct 8 decomposes to the carbene complex [RuCl(CHCO2Et)(PNNP)]+ (10), whose reaction with EDA gives diethyl maleate. This unprecedented mechanism is rationalized on the basis of the nucleophilic nature of diazoalkanes, which is enhanced by coordination to a π-back-donating metal such as ruthenium(II).
- Egloff, Joel,Ranocchiari, Marco,Schira, Amata,Schotes, Christoph,Mezzetti, Antonio
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- Dominant Disrotatory Double Rotation in the Thermally Induced 1,2-Dimethylspiropentane Geometric Isomerization
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Pyrolysis of optically active trans-1,2-dimethylspiropentane and syn-4,4-dideuterio-cis-1,2-dimethylspiropentane at 290.0 deg C in the vapor-phase allowed determination of kT->C + kC->T = 3.43E-5 /s, Keq(T/C) = 2.41, kTact->Trac = 1.36E-5 /s, and kCS->CS+CA = 8.76E-5 /s.This data indicates preferred double over single rotation in the cleavage of the C-1, C-2 bond, particularly with the cis isomer.The greater preference for double inversion over single inversion from the cis relative to the trans isomer suggests that the double inversion occurs by a disrotatory pathway.Pyrolysis of optically active trans,medial- and trans,proximal-1,2,4-trimethylspiropentanes at low conversions revealed that the previously observed interconversions of these isomers occur predominantly by C-4, C-5 bond cleavage and not by double rotation after C-1, C-2 bond fission.These observations reinforce the conclusion above that the dominant pathway for double rotation in spiropentane isomers is disrotatory.
- Gajewski, Joseph J.,Chang, Ming Jing
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- Iridium-catalyzed aziridination of aliphatic aldehydes, aliphatic amines and ethyl diazoacetate
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Three-component coupling reactions of aliphatic aldehydes, aliphatic amines and ethyl diazoacetate to the corresponding aziridine derivatives has been achieved by the use of [Ir(cod)Cl]2 as a catalyst under mild conditions; for instance, the reaction of n-butyraldehyde, tert-butylamine and ethyl diazoacetate in the presence of a catalytic amount of [Ir(cod)Cl]2 in THF at -10 °C gave 1-tert-butyl-2-ethoxycarbonyl-3-propylaziridine in 85% yield in high stereoselectivity (cis: trans = 96:4).
- Kubo, Takashi,Sakaguchi, Satoshi,Ishii, Yasutaka
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- Stable N-heterocyclic carbene (NHC)-palladium(0) complexes as active catalysts for olefin cyclopropanation reactions with ethyl diazoacetate
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The Pd0 complexes [(NHC)PdLn] (NHC=N-heterocyclic carbene ligand; L=styrene for n=2 or PR3 for n=1) efficiently catalyse olefin cyclopropanation by using ethyl diazoacetate (EDA) as the carbene source with activities that improve on previously described catalytic systems based on this metal. Mechanistic studies have shown that all of these catalyst precursors deliver the same catalytic species in solution, that is, [(IPr)Pd(sty)], a 14e- unsaturated intermediate that further reacts with EDA to afford [(IPr)Pd(=CHCO2Et)(sty)], from which the cyclopropane is formed.
- Martin, Carmen,Molina, Francisco,Alvarez, Eleuterio,Belderrain, Tomas R.
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- A family of highly active copper(I)-homoscorpionate catalysts for the alkyne cyclopropenation reaction
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Equimolar mixtures of ethyl diazoacetate and alkynes can be converted into cyclopropenes in very high yields, at room temperature, through the intermediacy of readily available Cu(I) catalysts containing trispyrazolylborate ligands.
- Diaz-Requejo,Mairena,Belderrain,Nicasio,Trofimenko,Perez
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- The role of the support properties in the catalytic performance of an anchored copper(ii) aza-bis(oxazoline) in mesoporous silicas and their carbon replicas
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A copper(ii) chiral aza-bis(oxazoline) catalyst (CuazaBox) was anchored onto ordered mesoporous silicas and their carbon replicas. The materials were characterized by elemental analysis (C, N, H, S), ICP-AES, FTIR, XPS, thermogravimetry and isotherms of N2 adsorption at -196 °C. The materials were tested as heterogeneous catalysts in the reaction of cyclopropanation of styrene to check the effect of porous material type on the catalytic parameters, as well as on their reutilization. Generally, the composites were more active and enantioselective in the cyclopropanation of styrene than the corresponding homogeneous phase reaction run under similar experimental conditions. The materials pHpzc proved to be an important factor not only in the CuazaBox anchoring yields, but also in their catalytic performance. Less acidic surfaces (SPSi and CMK-3) yielded heterogeneous catalysts with higher styrene conversion and enantioselectivity. The materials could also be recycled with comparable enantioselectivities or generally a slight decrease in the enantioselectivity.
- Silva, Ana Rosa,Guimaraes, Vanessa,Carvalho, Ana Paula,Pires, Joao
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- Metal-organic framework based on copper(I) sulfate and 4,4′- bipyridine catalyzes the cyclopropanation of styrene
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The hydrothermal synthesis of a new metal-organic framework (MOF) formulated as Cu2(4,4′-bpy)2SO4· 6(H2O), [abbreviation: (1); bpy or 4,4′-bpy=4,4′- bipyridine; SO42-=sulfate group] has been reported. The structure of this MOF consists of Cu+ nodes connected via 4,4′-bpy to form infinite chains, with two neighboring chains further bridged on the nodes by SO42-, resulting in a 1-D double chain network. Guest water molecules reside in between the chains and are hydrogen-bonded to the O and S atoms from the nearest sulfate groups, leading to the formation of a 3-D supramolecular framework. This MOF is good heterogeneous catalyst for the cyclopropanation of styrene, with high trans cyclopropane diastereoselectivity and was recycled and reused for three consecutive cycles without a significant loss of catalytic activity.
- Shi, Fa-Nian,Silva, Ana Rosa,Rocha, Joao
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- Crystal structures of sodium dimethyl sulfosuccinate and sodium diethyl sulfosuccinate
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The crystal structures of sodium dimethyl sulfosuccinate and sodium diethyl sulfosuccinate have been determined by the single crystal X-ray diffraction method. Sodium dimethyl sulfosuccinate (SDMS, C6H9O7SNa·H2O, Mr = 266.20) crystallizes in a triclinic space group P1 with unit cell dimensions a = 5.5971 (8), b = 6.5388 (5), c = 15.267 (2) A, α = 77.855 (8), β = 85.90 (1), γ = 84.95 (1)°. The crystal of sodium diethyl sulfosuccinate (SDES, C8H13O7SNa·3H2O, Mr = 330.29) has a monoclinic space group C2/c with unit cell dimensions a = 34.754 (3), b = 6.0322 (7), c = 15.0777 (9) A, β = 104.385 (7)°. In the SDMS and SDES crystals, the Na+ ion, which is coordinated to six oxygen atoms, forms an octahedral structure. For SDMS, the Na+ ion is coordinated to four oxygen atoms of SO3/- groups and to the two oxygen atoms of water molecules of hydration. For SDES, the Na+ ion is coordinated to the oxygen atom of the β-chain C=O group, one of the SO3/- oxygen atoms and four oxygen atoms of hydrating water molecules. It was found that splitting of the C=O stretch band caused by the Na...O=C coordination occurs in the IR and Raman spectra of SDES.
- Nagasoe, Yasuyuki,Hattori, Norikatsu,Masuda, Hideki,Okabayashi, Hirofumi,O'Connor, Charmian J.
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- Rh-mediated polymerization of carbenes: Mechanism and stereoregulation
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Ligand variation, kinetic investigations, and computational studies have been used to elucidate the mechanism of rhodium-catalyzed diazoalkane polymerization. Variations in the "N,O" donor part of the catalyst precursors (diene)RhI(N,O) result in different activities but virtually identical molecular weights, indicating that this part of the precursor is lost on forming the active species. In contrast, variation of the diene has a major effect on the nature of the polymer produced, indicating that the diene remains bound during polymerization. Kinetic studies indicate that only a small fraction of the Rh (1-5%) is involved in polymerization catalysis; the linear relation between polymer yield and Mw suggests that the chains terminate slowly and chain transfer is not observed (near living character). Oligomers and fumarate/maleate byproducts are most likely formed from other "active" species. Calculations support a chain propagation mechanism involving diazoalkane coordination at the carbon atom, N2 elimination to form a carbene complex, and carbene migratory insertion into the growing alkyl chain. N2 elimination is calculated to be the rate-limiting step. On the basis of a comparison of NMR data with those of known oligomer fragments, the stereochemistry of the new polymer is tentatively assigned as syndiotactic. The observed syndiospecificity is attributed to chain-end control on the rate of N2 elimination from diastereomeric diazoalkane complexes and/or on the migratory insertion step itself.
- Jellema, Erica,Budzelaar, Peter H. M.,Reek, Joost N. H.,De Bruin, Bas
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- New N-methylimidazolium hexachloroantimonate: Synthesis, crystal structure, Hirshfeld surface and catalytic activity of in cyclopropanation of stryrene
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The N-methylimidazolium hexachloroantimonate salt Cl6Sb·C4H7N2 (MIMSb), was prepared and fully characterized. In 1H NMR spectrum, the N-H proton shifted to downfield because of the presence of SbCl6? and appears as a triplet at 13.19 ppm. Characterization with IR spectroscopy shows strong absorption band at around 699 cm?1 which is attributed to Sb?Cl stretching. Furthermore, UV–visible analysis at high concentrations in DMSO suggested that MIMSb interacts with DMSO leading to an absorption in visible region at λmax of 426 nm. Electrochemical characterization using cyclic voltammetry demonstrates three redox processes with reduction peaks at 0.69, ?0.13 and ?0.50 V. Finally, molecular structure of the product was determined by X-ray diffraction analysis. The crystal structure determination was carried out with Mo-Kα X-ray and data measured at 100 K. The title compound crystallizes in monoclinic P21/c space group with unit cell parameters a = 7.1131 (5) ?, b = 12.4436 (9) ?, c = 14.1658 (11) ?, V = 1241.86 (16) ?3 and Z = 4. The crystal packing is stabilized by H—Cl interaction. The analysis of intermolecular interactions was realized through the mapping of contact descriptors dnorm, shape-index and the fingerprint reveling that the most significant contribution to the Hirshfeld surface (69.4%) is from H—Cl contacts. Finally, the catalytic activity of MIMSb was probed in the cyclopropanation of styrene with ethyl diazoacetate.
- Boschini, Frédéric,Mahmoud, Abdelfattah,Sénam Etsè, Koffi,Zaragoza, Guillermo
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- Synthesis, structure and reactivity of iridium complexes containing a bis-cyclometalated tridentate C^N^C ligand
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In an effort to synthesize cyclometalated iridium complexes containing a tridentate C^N^C ligand, transmetallation of [Hg(HC^N^C)Cl] (1) (H2C^N^C = 2,6-bis(4-tert-butylphenyl)pyridine) with various organoiridium starting materials has been studied. The treatment of1with [Ir(cod)Cl]2(cod = 1,5-cyclooctadiene) in acetonitrile at room temperature afforded a hexanuclear Ir4Hg2complex, [Cl(κ2C,N-HC^N^C)(cod)IrHgIr(cod)Cl2]2(2), which features Ir-Hg-Ir and Ir-Cl-Ir bridges. Refluxing2with sodium acetate in tetrahydrofuran (thf) resulted in cyclometalation of the bidentate HC^N^C ligand and formation of trinuclear [(C^N^C)(cod)IrHgIr(cod)Cl2] (3). On the other hand, refluxing [Ir(cod)Cl]2with1and sodium acetate in thf yielded [Ir(C^N^C)(cod)(HgCl)] (4). Chlorination of4with PhICl2gave [Ir(C^N^C)(cod)Cl]·HgCl2(5·HgCl2) that reacted with tricyclohexylphosphine to yield Hg-free [Ir(C^N^C)(cod)Cl] (5). Chloride abstraction of5with silver(i) triflate (AgOTf) gave [Ir(C^N^C)(cod)(H2O)](OTf) (6) that can catalyze the cyclopropanation of styrene with ethyl diazoacetate. Reaction of1and [Ir(CO)2Cl(py)] (py = pyridine) with sodium acetate in refluxing thf afforded [Ir(C^N^C)(HgCl)(py)(CO)] (7), in which the carbonyl ligand is coplanar with the C^N^C ligand. On the other hand, refluxing1with (PPh4)[Ir(CO)2Cl2] and sodium acetate in acetonitrile gave [Ir(C^N^C)(κ2C,N-HC^N^C)(CO)] (8), the carbonyl ligand of which istransto the pyridyl ring of the bidentate HC^N^C ligand. Upon irradiation with UV light8in thf was isomerized to8′, in which the carbonyl istransto a phenyl group of the bidentate HC^N^C ligand. The isomer pair8and8′exhibited emission at 548 and 514 nm in EtOH/MeOH at 77 K with lifetime of 84.0 and 64.6 μs, respectively. Protonation of8withp-toluenesulfonic acid (TsOH) afforded the bis(bidentate) tosylate complex [Ir(κ2C,N-HC^N^C)2(CO)(OTs)] (9) that could be reconverted to8upon treatment with sodium acetate. The electrochemistry of the Ir(C^N^C) complexes has been studied using cyclic voltammetry. Reaction of [Ir(PPh3)3Cl] with1and sodium acetate in refluxing thf led to isolation of the previously reported compound [Ir(κ2P,C-C6H4PPh2)2(PPh3)Cl] (10). The crystal structures of2-5,8,8′,9and10have been determined.
- Cheng, Shun-Cheung,Cheung, Wai-Man,Chong, Man-Chun,Ko, Chi-Chiu,Leung, Wa-Hung,Sung, Herman H.-Y.,Williams, Ian D.
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- Highly stereoselective formation of cis-enediones from α-diazo carbonyl compounds catalysed by [RuCl(η5-C5H5)PPh32]
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Stereoselective decomposition of the α-diazo carbonyl compounds N2CHCOR [R = Me, Prn, Pri, (CH2)10CH3] catalysed by [RuCl(η5-C5H5)(PPh3) 2] (0.1 mol%) in toluene at 65°C affords quantitatively RCOCH=CHCOR carbene dimers, the cis isomers being formed in 95-97% yield; under the same experimental conditions N2CHCOEt gives diethyl maleate in a purity of greater than 99%, the highest value for a stereoselective carbene-carbene dimer formation reported to date.
- Baratta, Walter,Del Zotto, Alessandro,Rigo, Pierluigi
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- The effect of catalyst loading in copper-catalyzed cyclohexane functionalization by carbene insertion
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A study of the variables that affect the insertion of the :CHCO 2Et group (formed from ethyl diazocetate, EDA) into the C-H bonds of cyclohexane in the presence of a TpxCu complex as the catalyst (Tpx = trispyrazolylborate ligand) has demonstrated an anomalous effect of the catalyst loading. The use of low concentrations of catalyst produces an increase in the yield of the C-H activation product ethyl cyclohexaneacetate. This effect has also been found in the case of other less elaborated catalysts such as [BpBr3Cu] or [(bipy)2-Cu][I]. Wiley-VCH Verlag GmbH & Co. KGaA, 2007.
- Caballero, Ana,Diaz-Requejo, M. Mar,Trofimenko, Swiatoslaw,Belderrain, Tomas R.,Perez, Pedro J.
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- One-pot production of diethyl maleate via catalytic conversion of raw lignocellulosic biomass
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The conversion of lignocellulose into a value-added chemical with high selectivity is of great significance but is a big challenge due to the structural diversities of biomass components. Here, we have reported an efficient approach for the one-step conversion of raw lignocellulose into diethyl maleate by the polyoxometalate ionic liquid [BSmim]CuPW12O40 in ethanol under mild conditions. The results reveal that all of the fractions in biomass, i.e., cellulose, lignin and hemicellulose, were simultaneously converted into diethyl maleate (DEM), achieving a 329.6 mg g-1 yield and 70.3% selectivity from corn stalk. Importantly, the performance of the ionic liquid catalyst [BSmim]CuPW12O40 was nearly twice that of CuHPW12O40, which can be attributed to the lower incorporation of the Cu2+ site in [BSmim]CuPW12O40. Hence, this process opens a promising route for producing bio-based bulk chemicals from raw lignocellulose without any pretreatment.
- Cai, Zhenping,Chen, Rujia,Zhang, Hao,Li, Fukun,Long, Jinxing,Jiang, Lilong,Li, Xuehui
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supporting information
p. 10116 - 10122
(2021/12/24)
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- Practical and Regioselective Synthesis of C-4-Alkylated Pyridines
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The direct position-selective C-4 alkylation of pyridines has been a long-standing challenge in heterocyclic chemistry, particularly from pyridine itself. Historically this has been addressed using prefunctionalized materials to avoid overalkylation and mixtures of regioisomers. This study reports the invention of a simple maleate-derived blocking group for pyridines that enables exquisite control for Minisci-type decarboxylative alkylation at C-4 that allows for inexpensive access to these valuable building blocks. The method is employed on a variety of different pyridines and carboxylic acid alkyl donors, is operationally simple and scalable, and is applied to access known structures in a rapid and inexpensive fashion. Finally, this work points to an interesting strategic departure for the use of Minisci chemistry at the earliest possible stage (native pyridine) rather than current dogma that almost exclusively employs Minisci chemistry as a late-stage functionalization technique.
- Baran, Phil S.,Choi, Jin,Godineau, Edouard,Laudadio, Gabriele
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supporting information
p. 11927 - 11933
(2021/08/20)
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- Comparative Study of the Electronic Structures of μ-Oxo, μ-Nitrido, and μ-Carbido Diiron Octapropylporphyrazine Complexes and Their Catalytic Activity in Cyclopropanation of Olefins
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The electronic structure of three single-Atom bridged diiron octapropylporphyrazine complexes (FePzPr8)2X having Fe(III)-O-Fe(III), Fe(III)-N-Fe(IV) and Fe(IV)-C-Fe(IV) structural units was investigated by M?ssbauer spectroscopy and density functional theory (DFT) calculations. In this series, the isomer shift values decrease, whereas the values of quadrupole splitting become progressively greater indicating the increase of covalency of Fe-X bond in the μ-oxo, μ-nitrido, μ-carbido row. The M?ssbauer data point to low-spin systems for the three complexes, and calculated data with B3LYP-D3 show a singlet state for μ-oxo and μ-carbido and a doublet state for μ-nitrido complexes. An excellent agreement was obtained between B3LYP-D3 optimized geometries and X-ray structural data. Among (FePzPr8)2X complexes, μ-oxo diiron species showed a higher reactivity in the cyclopropanation of styrene by ethyl diazoacetate to afford a 95% product yield with 0.1 mol % catalyst loading. A detailed DFT study allowed to get insight into electronic structure of binuclear carbene species and to confirm their involvement into carbene transfer reactions.
- Cailler, Lucie P.,Clémancey, Martin,Barilone, Jessica,Maldivi, Pascale,Latour, Jean-Marc,Sorokin, Alexander B.
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p. 1104 - 1116
(2020/02/04)
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- Iron/N-doped graphene nano-structured catalysts for general cyclopropanation of olefins
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The first examples of heterogeneous Fe-catalysed cyclopropanation reactions are presented. Pyrolysis of in situ-generated iron/phenanthroline complexes in the presence of a carbonaceous material leads to specific supported nanosized iron particles, which are effective catalysts for carbene transfer reactions. Using olefins as substrates, cyclopropanes are obtained in high yields and moderate diastereoselectivities. The developed protocol is scalable and the activity of the recycled catalyst after deactivation can be effectively restored using an oxidative reactivation protocol under mild conditions. This journal is
- Bartling, Stephan,Beller, Matthias,Ferretti, Francesco,Formenti, Dario,Junge, Kathrin,Kreyenschulte, Carsten,Ragaini, Fabio,Sarkar, Abhijnan
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p. 6217 - 6221
(2020/08/24)
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- Method for preparing maleate by catalyzing maleic anhydride with ionic liquid
-
The invention discloses a method for preparing maleate by catalyzing maleic anhydride with ionic liquid. The preparation method is characterized by comprising the following steps: mixing ionic liquidwith maleic anhydride and fatty alcohol, carrying out heating to 80-140 DEG C, and performing a reaction for 0.5-4 h to obtain maleate, wherein the usage amount of the ionic liquid accounts for 0.1-10% by mol of the maleic anhydride, and a molar ratio of fatty alcohol to maleic anhydride is 2-12. A high-added-value chemical with the completely-esterified maleate as a main product is prepared in the invention. The method is simple in process, mild in conditions, friendly to environment and high in double esterification degree; and the ionic liquid is high in activity, not prone to inactivationand capable of being cyclically used.
- -
-
Paragraph 0037; 0040; 0041; 0044
(2020/02/29)
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- A comparative study on degradation of complex malathion organophosphate using of Escherichia coli IES-02 and a novel carboxylesterase
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Malathion organophosphates considered as the major constituent of herbicides, pesticides and insecticides. Extensively used in agricultural, horticultures and for numerous household applications contributes to precedence organic pollutants leading antagonistic effects on human health and environment. Therefore detoxification of malathion from contaminated site is of general interest. Simultaneously it is very emerging to isolated novel indigenous microbial strains from contaminated site with a record of pesticide application. In this study Escherichia coli IES-02 isolated from malathion contaminant effluent and the strain showed maximum efficiency in malathion degradation that utilized it as the sole source of carbon. Carboxylesterase (33.0, 30.0, 28.0 kDa) were purified (1685.71 U/mg) from Escherichia coli IES-02 showed significant results in malathion degradation approximately 81% within 20 min as compared with Escherichia coli IES-02 cells within 4 h (99.0 to 95.0%) into monocarboxylic acid and diacid derivatives. The generation time of Escherichia coli was also observed at 60 min with 0.1 ppm, 68 min with 0.5 ppm, 74.5 min with 2.0 ppm and 91.37 min with 50 ppm of malathion. The degradation rate and transformation metabolites were estimated by Gas Chromatography-Mass Spectrometry respectively. Malathion metabolites pathway proposed in this study which revealed the potential application against lethal environmental pollution.
- Ansari, Asma,Iqbal, Sajid,Khan, Moazzam Ali,Qader, Shah Ali Ul,Sattar, Hafsa,Sirajuddin, Sadia
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p. 445 - 455
(2020/01/08)
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- Deoxygenation of Epoxides with Carbon Monoxide
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The use of carbon monoxide as a direct reducing agent for the deoxygenation of terminal and internal epoxides to the respective olefins is presented. This reaction is homogeneously catalyzed by a carbonyl pincer-iridium(I) complex in combination with a Lewis acid co-catalyst to achieve a pre-activation of the epoxide substrate, as well as the elimination of CO2 from a γ-2-iridabutyrolactone intermediate. Especially terminal alkyl epoxides react smoothly and without significant isomerization to the internal olefins under CO atmosphere in benzene or toluene at 80–120 °C. Detailed investigations reveal a substrate-dependent change in the mechanism for the epoxide C?O bond activation between an oxidative addition under retention of the configuration and an SN2 reaction that leads to an inversion of the configuration.
- Maulbetsch, Theo,Jürgens, Eva,Kunz, Doris
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p. 10634 - 10640
(2020/07/30)
-
- Thermal defect engineering of precious group metal-organic frameworks: Impact on the catalytic cyclopropanation reaction
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We report on the engineering of defects in precious group metal (PGM)-based HKUST-1 (Hong Kong University of Science and Technology) analogues (RhII,II, RuII,II, RuII,III) and the ramification on the catalytic activity by using the cyclopropanation of styrene with ethyl diazoacetate (EDA) as an analytical probe to investigate complex metal-organic framework (MOF) structures. We have characterized the active sites within the extended frameworks by their activity, product distribution and stereoselectivity. The role of the metal, its oxidation state and the availability of open metal sites is elucidated. With a set of 17 samples including reference to Cu-HKUST-1, metal nanoparticles and existing literature, conclusions on the tuneability of paddlewheel complexes within self-supported porous and crystalline frameworks are presented. In particular, additional axial ligands (OAc-/Cl-) accounting for charge compensation at the mixed-valent RuII,III nodes seem responsible for side-product formation during catalysis. Thermal defect-engineering allows for controlled and preferential removal of those axial ligands accompanied by reduction of the average metal oxidation state. This enhances the number of open metal sites (OMS) and the catalytic activity as well as improving the chemoselectivity towards cyclopropanes. The preference towards formation of trans-cyclopropane is assigned to the steric crowding of the paddlewheel moiety. This diastereoselectivity gradually diminishes with rising defectiveness of the PGM-HKUST-1 analogues featuring modified paddlewheel nodes.
- Heinz, Werner R.,Junk, Raphael,Agirrezabal-Telleria, Iker,Bueken, Bart,Bunzen, Hana,G?lz, Thorsten,Cokoja, Mirza,De Vos, Dirk,Fischer, Roland A.
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p. 8077 - 8085
(2020/12/31)
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- A General One-Pot Methodology for the Preparation of Mono- and Bimetallic Nanoparticles Supported on Carbon Nanotubes: Application in the Semi-hydrogenation of Alkynes and Acetylene
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A facile and straightforward methodology for the preparation of monometallic (copper and palladium) and bimetallic nanocatalysts (NiCu and PdCu) stabilized by a N-heterocyclic carbene ligand is reported. Both colloidal and supported nanoparticles (NPs) on carbon nanotubes (CNTs) were prepared in a one-pot synthesis with outstanding control on their size, morphology and composition. These catalysts were evaluated in the selective hydrogenation of alkynes and alkynols. PdCu/CNTs revealed an efficient catalytic system providing high selectivity in the hydrogenation of terminal and internal alkynes. Moreover, this catalyst was tested in the semi-hydrogenation of acetylene in industrially relevant acetylene/ethylene-rich model gas feeds and showed excellent stability even after 40 h of reaction.
- Lomelí-Rosales, Diego A.,Delgado, Jorge A.,Díaz de los Bernardos, Miriam,Pérez-Rodríguez, Sara,Gual, Aitor,Claver, Carmen,Godard, Cyril
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supporting information
p. 8321 - 8331
(2019/06/04)
-
- Gold-catalyzed ethylene cyclopropanation
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Ethylene can be directly converted into ethyl 1-cyclopropylcarboxylate upon reaction with ethyl diazoacetate (N2CHCO2Et, EDA) in the presence of catalytic amounts of IPrAuCl/NaBArF4 (IPr = 1,3-bis(2,6-diisopropylphenyl)imidazole-2-ylidene; BArF4 = tetrakis(3,5-bis(trifluoromethyl)phenyl)borate).
- Rull, Silvia G.,Olmos, Andrea,Pérez, Pedro J.
-
-
- Generation and Reactivity of Electron-Rich Carbenes on the Surface of Catalytic Gold Nanoparticles
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The reactive nature of carbenes can be modulated, and ultimately reversed, by receiving additional electron density from a metal. Here, it is shown that Au nanoparticles (NPs) generate an electron-rich carbene on surface after transferring electron density to the carbonyl group of an in situ activated diazoacetate, as assessed by Fourier transformed infrared (FT-IR) spectroscopy, magic angle spinning nuclear magnetic resonance (MAS NMR), and Raman spectroscopy. Density functional theory (DFT) calculations support the observed experimental values and unveil the participation of at least three different Au atoms during carbene stabilization. The surface stabilized carbene shows an extraordinary stability against nucleophiles and reacts with electrophiles to give new products. These findings showcase the ability of catalytic Au NPs to inject electron density in energetically high but symmetrically allowed valence orbitals of sluggish molecules.
- Oliver-Meseguer, Judit,Boronat, Mercedes,Vidal-Moya, Alejandro,Concepción, Patricia,Rivero-Crespo, Miguel ángel,Leyva-Pérez, Antonio,Corma, Avelino
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supporting information
p. 3215 - 3218
(2018/03/13)
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- MODULATOR OF CYSTIC FIBROSIS TRANSMEMBRANE CONDUCTANCE REGULATOR, PHARMACEUTICAL COMPOSITIONS, METHODS OF TREATMENT, AND PROCESS FOR MAKING THE MODULATOR
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Compounds of Formula (I) pharmaceutically acceptable salts thereof, deuterated derivatives of any of the foregoing, and metabolites of any of the foregoing are disclosed. Pharmaceutical compositions comprising the same, methods of treating cystic fibrosis using the same, and methods for making the same are also disclosed. Also disclosed are solid state forms of Compound 1 and salts and solvates thereof.
- -
-
Page/Page column 285; 287; 288
(2018/06/30)
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- Synthesis, characterization, and catalytic evaluation of ruthenium-diphosphine complexes bearing xanthate ligands
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The reaction of [RuCl2(p-cymene)]2 with potassium O-ethylxanthate and a set of nine representative Ph2P-X-PPh2 bidentate phosphines (dppm, dppe, dppp, dppb, dpppe, dppen, dppbz, dppf, and DPEphos) afforded monometallic [Ru(S2COEt)2(diphos)] chelates 1-9 in 62-96% yield. All the products were fully characterized by using various analytical techniques and their molecular structures were determined by X-ray crystallography. They featured a highly distorted octahedral geometry with a S-Ru-S bite angle close to 72° and P-Ru-P angles ranging between 73° and 103°. Bond lengths and IR stretching frequencies recorded for the anionic xanthate ligands strongly suggested a significant contribution of the EtO+CS22- resonance form. 1H NMR and XRD analyses showed that the methylene protons of the ethyl groups were diastereotopic due to a strong locking of their conformation by a neighboring phenyl ring. On cyclic voltammetry, quasi-reversible waves were observed for the Ru2+/Ru3+ redox couples with E1/2 values ranging between 0.65 and 0.80 V vs. Ag/AgCl. The activity of chelates 1-9 was probed in three catalytic processes, viz., the synthesis of vinyl esters from benzoic acid and 1-hexyne, the cyclopropanation of styrene with ethyl diazoacetate, and the atom transfer radical addition of carbon tetrachloride and methyl methacrylate. In the first case, 31P NMR analysis of the reaction mixtures showed that the starting complexes remained mostly unaltered despite the harsh thermal treatment that was applied to them. In the second case, monitoring the rate of nitrogen evolution revealed that all the catalysts under investigation behaved similarly and were rather slow initiators. In the third case, [Ru(S2COEt)2(dppm)] was singled out as a very active and selective catalyst already at 140 °C, whereas most of the other complexes resisted degradation up to 160 °C and were only moderately active. Altogether, these results were in line with the high stability displayed by [Ru(S2COEt)2(diphos)] chelates 1-9.
- Zain Aldin, Mohammed,Maho, Anthony,Zaragoza, Guillermo,Demonceau, Albert,Delaude, Lionel
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p. 13926 - 13938
(2018/10/20)
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- Unexpected formation of a μ-carbido diruthenium(IV) complex during the metalation of phthalocyanine with Ru3(CO)12 and its catalytic actIVity in carbene transfer reactions
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A μ-carbido diruthenium(iv) phthalocyanine complex was prepared for the first time from the free-base octabutoxyphthalocyanine by direct metalation with Ru3(CO)12. The first examples of the catalytic activity of Ru(iv) binuclear phthalocyanines were demonstrated by the cyclopropanation of aromatic olefins and carbene insertion into the N-H bonds of aromatic or aliphatic amines with turnover numbers of 680-1000 and 580-1000, respectively.
- Kroitor, Andrey P.,Cailler, Lucie P.,Martynov, Alexander G.,Gorbunova, Yulia G.,Tsivadze, Aslan Yu.,Sorokin, Alexander B.
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supporting information
p. 15651 - 15655
(2017/12/02)
-
- Photoorganocatalytic synthesis of lactones: Via a selective C-H activation-alkylation of alcohols
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Selective C-H activation is an area of growing importance in modern organic chemistry. Herein, we report our efforts in combining organocatalysis and photocatalysis for the development of a highly efficient and selective visible-light mediated protocol for the C-H activation and addition of various alcohols to a plethora of Michael acceptors, followed by a cyclization reaction leading to lactones, a repeatedly occurring motif in nature. Utilizing phenylglyoxylic acid as the photocatalyst and common household bulbs as the light source, we describe a versatile α-alkylation/lactonization of alcohols with α,β-unsaturated esters leading to products in excellent yields. The reaction mechanism was extensively studied.
- Kaplaneris, Nikolaos,Bisticha, Aikaterini,Papadopoulos, Giorgos N.,Limnios, Dimitris,Kokotos, Christoforos G.
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supporting information
p. 4451 - 4456
(2017/09/29)
-
- Method of selectively catalytically oxidizing biomass-based furan compound
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The invention discloses a method of selectively catalytically oxidizing a biomass-based furan compound. The method comprises the following step of: by taking a heteropolyacid functional ionic liquid as a catalyst and an alcohol solution as a reaction medium, obtaining dicarboxylic acid or dicarboxylate in the conditions that the reaction temperature is 100-150 DEG C, the reaction time is 1-3h and the oxygen pressure is 0.5-1.0MPa, wherein over 62.35% of difumarate selectivity is obtained. The single chemical yield and selectivity for oxidizing preparation of a biomass-based furan derivative are far higher than those of the prior art. The method has the remarkable advantage that an ionic liquid catalyst can be recovered and recycled by simply adjusting the temperature. The method disclosed by the invention is mild in reaction condition, green and safe in process and simple to operate, and can realize intermittent and continuous production.
- -
-
Paragraph 0098-0101
(2017/07/19)
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- Stereoselective cyclopropanation under solvent free conditions: Catalyzed by a green and efficient recyclable Cu-exchanged bentonite
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Background: The cyclopropanation reaction was inspected by addition of carbene generated from ethyl diazoacetate in the presence of a greener Cu-exchanged bentonite catalyst to olefin under solvent free condition. The cyclopropanes were obtained with good yields. Our own contribution in this area was to introduce a modified Algerian bentonite as a catalyst and microwave activation as a mode of heating. Methods: A catalytic material developed from natural type montmorillonite clays, from deposits of Maghnia (Western Algeria), by cation exchange (Cu2+) was characterized by different spectral methods. The catalytic properties of the new material were explored in cyclopropanation reaction of olefins under microwave irradiation. A comparative study with Cu-exchanged bentonite as catalyst between microwave activation and classical heating was conducted. Results: Cu2+ exchanged clay is an efficient catalyst in the generation of carbenes from diazocompounds, under microwave irradiation. The formation of carboxylate cyclopropane was performed in solvent free condition with moderate diastereoselectivity. The yields were good, and the catalyst can be reused at least three times without noticeable loss of catalytic activity. Conclusion: This work shows that the coupling "modified clay/microwave activation" is a clean and simple access to functionalized cyclopropanes. This reusable Cu exchanged clay material is shown to be as a good substitute for many sophisticated and hardly accessible catalysts.
- Bendeddouche, Choukry K.,Adjdir, Mehdi,Benhaoua, Hadj
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p. 217 - 223
(2016/03/01)
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- Synthesis and catalytic applications of 1,2,3-triazolylidene gold(i) complexes in silver-free oxazoline syntheses and C-H bond activation
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A series of novel 1,2,3-triazolylidene gold(i) chloride complexes have been synthesised and fully characterised. Silver-free methodologies for chloride ion abstraction of these complexes were evaluated for their potential as Au-based catalyst precursors. Using simple potassium salts or MeOTf as chloride scavengers produced metal complexes that catalyse both the regioselective synthesis of oxazolines and the C-H activation of benzene or styrene for carbene transfer from ethyl diazoacetate. These results indicate that Ag-free activation of 1,2,3-triazolylidene gold(i) chloride complexes is feasible for the generation of catalytically active Au triazolylidene species. However, silver-mediated activation imparts substantially higher catalytic activity in oxazoline synthesis.
- Pretorius, René,Fructos, Manuel R.,Müller-Bunz, Helge,Gossage, Robert A.,Pérez, Pedro J.,Albrecht, Martin
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p. 14591 - 14602
(2016/09/28)
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- Enantiopure Chiral Concave 1,10-Phenanthrolines
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Chiral information has been introduced into concave 1,10-phenanthrolines of different ring sizes by using a 2,7-disubstituted naphthalene bridgehead, which causes axial chirality. A tetraphenolic 2-(dihydroxynaphthyl)-9-(dihydroxyphenyl)-1,10-phenanthroline was synthesized as a key intermediate. Two strategies were followed to obtain the bimacrocyclic chiral concave 1,10-phenanthrolines: quadruple Williamson ether synthesis or alkenylation of the OH groups and subsequent ring-closing metathesis followed by hydrogenation. The overall yields of bimacrocyles 19 were 10 to 17 % starting from the respective Suzuki coupling of the substituted arenes 11 and 13 to 2,9-dichloro-1,10-phenanthroline (5). Racemic mixtures of the three concave 1,10-phenanthrolines 19 were separated by using chiral high-performance liquid chromatography (HPLC) techniques, and their absolute stereochemistry was assigned by comparison of simulated and experimental circular dichroism (CD) spectra. The enantiopure concave 1,10-phenanthrolines were used as ligands in a copper-catalysed cyclopropanation, and their selectivity was determined by chiral gas chromatography (GC).
- Reck, Lisa M.,Haberhauer, Gebhard,Lüning, Ulrich
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p. 1119 - 1131
(2016/03/05)
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- Design of Core-Pd/Shell-Ag Nanocomposite Catalyst for Selective Semihydrogenation of Alkynes
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We designed core-Pd/shell-Ag nanocomposite catalyst (Pd@Ag) for highly selective semihydrogenation of alkynes. The construction of the core-shell nanocomposite enables a significant improvement in the low activity of Ag NPs for the selective semihydrogenation of alkynes because hydrogen is supplied from the core-Pd NPs to the shell-Ag NPs in a synergistic manner. Simultaneously, coating the core-Pd NPs with shell-Ag NPs results in efficient suppression of overhydrogenation of alkenes by the Pd NPs. This complementary action of core-Pd and shell-Ag provides high chemoselectivity toward a wide range of alkenes with high Z-selectivity under mild reaction conditions (room temperature and 1 atm H2). Moreover, Pd@Ag can be easily separated from the reaction mixture and is reusable without loss of catalytic activity or selectivity.
- Mitsudome, Takato,Urayama, Teppei,Yamazaki, Kenji,Maehara, Yosuke,Yamasaki, Jun,Gohara, Kazutoshi,Maeno, Zen,Mizugaki, Tomoo,Jitsukawa, Koichiro,Kaneda, Kiyotomi
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supporting information
p. 666 - 670
(2016/02/18)
-
- Hemin-Catalyzed, Cyclodextrin-Assisted Insertion of Carbenoids into N-H Bonds
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An aqueous hemin-catalyzed, cyclodextrin-assisted N-H insertion reaction of α-diazo ester into aromatic amines is described here. This aqueous catalytic system showed good compatibility with various arylamines, with yields up to 96%. A size-controlled reaction phenomenon by different cyclodextrins (CDs) was also observed when ethyl diazoacetate (EDA) was used. The reaction mechanism was also preliminarily proposed on the basis of designed control experiments.
- Xu, Xiaofei,Li, Chang,Tao, Zhihao,Pan, Yuanjiang
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supporting information
p. 3341 - 3345
(2015/11/03)
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- Assessment of catalysis by arene-ruthenium complexes containing phosphane or NHC groups bearing pendant conjugated diene systems
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Two p-cymene-ruthenium complexes 1 and 2 were isolated in high yields by treating the [RuCl2(p-cymene)]2 dimer with new hybrid phosphane- or NHC-linked diene ligands. Both complexes were fully characterized by NMR spectroscopy, and the molecular structure of the ruthenium-p-cymene complex 1, containing the phosphane-diene ligand system, was determined by X-ray diffraction analysis. The catalytic activities of both compounds were probed in atom-transfer radical addition (ATRA) and polymerization (ATRP), in the cyclopropanation of olefins, in the ring-opening metathesis polymerization (ROMP) of norbornene, and in the synthesis of enol esters from hex-1-yne and 4-acetoxybenzoic acid.
- Baraut, Johann,Massard, Alexandre,Chotard, Florian,Bodio, Ewen,Picquet, Michel,Richard, Philippe,Borguet, Yannick,Nicks, Fran?ois,Demonceau, Albert,Le Gendre, Pierre
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supporting information
p. 2671 - 2682
(2015/06/22)
-
- Interfacing Microbial Styrene Production with a Biocompatible Cyclopropanation Reaction
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Abstract The introduction of new reactivity into living organisms is a major challenge in synthetic biology. Despite an increasing interest in both the development of small-molecule catalysts that are compatible with aqueous media and the engineering of enzymes to perform new chemistry in vitro, the integration of non-native reactivity into metabolic pathways for small-molecule production has been underexplored. Herein we report a biocompatible iron(III) phthalocyanine catalyst capable of efficient olefin cyclopropanation in the presence of a living microorganism. By interfacing this catalyst with E.coli engineered to produce styrene, we synthesized non-natural phenyl cyclopropanes directly from D-glucose in single-vessel fermentations. This process is the first example of the combination of nonbiological carbene-transfer reactivity with cellular metabolism for small-molecule production.
- Wallace, Stephen,Balskus, Emily P.
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supporting information
p. 7106 - 7109
(2015/06/08)
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- Catalytic activity and selectivity of a range of ruthenium complexes tested in the styrene/EDA reaction system
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The complex ensemble of competing chemical processes (cyclopropanation, metathesis, dimerisation) involved in the reaction of ethyl diazoacetate with styrene is examined in the presence of a panel of ten ruthenium complexes. Our results, focusing on the catalysts' activity and selectivity, showcased the new NHC-containing complex 10 and the Fischer carbene 7 as leading to best chemoselectivities for cyclopropanation while the bidentate Schiff-base complexes 3 and 4 provided highest stereoselectivity. The traditionally metathesis-active Grubbs I catalyst (5) could be manipulated, by working under high dilution, to display moderate activity in cyclopropanation whereas the Grubbs II catalyst (6) totally promoted metathesis. Data obtained with the above set of Ru complexes strongly support the premise that ligand structure and configuration in the Ru coordination sphere are essential factors in controlling the reaction pathways.
- Dragutan, Ileana,Ding, Fu,Sun, Ya-Guang,Verpoort, Francis,Dragutan, Valerian
-
-
- Synthesis, structural characterization, reactivity, and catalytic properties of copper(I) complexes with a series of tetradentate tripodal tris(pyrazolylmethyl)amine ligands
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Novel tris(pyrazolylmethyl)amine ligands TpaMe3, Tpa*,Br, and TpaBr3 have been synthesized and structurally characterized. The coordination chemistries of these three new tetradentate tripodal ligands and the already known Tpa and Tpa* have been explored using different copper(I) salts as starting materials. Cationic copper(I) complexes [TpaxCu]PF6 (1-4) have been isolated from the reaction of [Cu(NCMe)4]PF6 and 1 equiv of the ligand. Complexes 2 (Tpax = Tpa*) and 3 (Tpax = TpaMe3) have been characterized by X-ray studies. The former is a 1D helical coordination polymer, and the latter is a tetranuclear helicate. In both structures, the Tpax ligand adopts a μ2: κ2:κ1-coordination mode. However, in solution, all of the four complexes form fluxional species. When CuI is used as the copper(I) source, neutral compounds 5-8 have been obtained. Complexes 6-8 exhibit a 1:1 metal-to-ligand ratio, whereas 5 presents 2:1 stoichiometry. Its solid-state structure has been determined by X-ray diffraction, revealing its 3D polymeric nature. The polymer is composed by the assembly of [Tpa 2Cu4I4] units, in which Cu4I 4 presents a step-stair structure. The Tpa ligands bridge the Cu 4I4 clusters, adopting also a μ2: κ2:κ1-coordination mode. As observed for the cationic derivatives, the NMR spectra of 5-8 show the equivalence of the three pyrazolyl arms of the ligands in these complexes. The reactivities of cationic copper(I) derivatives 1-4 with PPh3 and CO have been explored. In all cases, 1:1 adducts [TpaxCuL]PF6 [L = PPh3 (9-11), CO (12-15)] have been isolated. The crystal structure of [Tpa*Cu(PPh3)]PF6 (9) has been obtained, showing that the coordination geometry around copper(I) is trigonal-pyramidal with the apical position occupied by the tertiary amine N atom. The Tpa* ligand binds the Cu center to three of its four N atoms, with one pyrazolyl arm remaining uncoordinated. In solution, the carbonyl adducts 13-15 exist as a mixture of two isomers; the four- and five-coordinate species can be distinguished by means of their IR νCO stretching bands. Finally, the catalytic activities of complexes 1-4 have been demonstrated in carbene- and nitrene-transfer reactions.
- Haldon, Estela,Delgado-Rebollo, Manuela,Prieto, Auxiliadora,Alvarez, Eleuterio,Maya, Celia,Nicasio, M. Carmen,Perez, Pedro J.
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supporting information
p. 4192 - 4201
(2014/05/06)
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- Iridium porphyrin catalyzed N-H insertion reactions: Scope and mechanism
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Ir(TTP)CH3 catalyzed N-H insertion reactions between ethyl diazoacetate (EDA) or methyl phenyldiazoacetate (MPDA) and a variety of aryl, aliphatic, primary, and secondary amines to generate substituted glycine esters with modest to high yields. Aniline substrates generally gave yields above 80%, with up to 105 catalyst turnovers, and without slow addition of the diazo reagent. Good yields were also achieved with aliphatic amines, though higher catalyst loadings and slow addition of the amine were necessary in some cases. Primary amines reacted with EDA to generate both single- and double-insertion products, either of which could be produced selectively in high yield with the proper choice of stoichiometric ratios and reaction temperature. Notably, mixed trisubstituted amines, RN(CH2CO2Et) (CHPhCO2Me), were generated from the insertion of 1 equiv of EDA and 1 equiv of MPDA into primary amines. The N-H insertion mechanism was examined using substrate competition studies, trapping experiments, and multiple spectroscopic techniques. Substrate competition studies using pairs of amines with EDA or MPDA revealed Hammett correlations with respective slopes of ρ = 0.15 and ρ+ = -0.56 as well as kinetic isotope ratios of k H/kD = 1.0 ± 0.2 and 2.7 ± 0.2. Competitive amine binding to the iridium center was demonstrated by kinetics and equilibrium binding studies. Equilibrium binding constants ranged from 102 to 105. Monitoring the reaction by absorption spectroscopy revealed a transient metalloporphyrin complex. The lifetime of this species was dependent on the nature of the amine substrate, which suggests that the catalytic cycle proceeds through a metal-ylide intermediate.
- Anding, Bernie J.,Woo, L. Keith
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p. 2599 - 2607
(2013/06/26)
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- METHOD FOR CONTINUOUSLY PREPARING CARBOXYLIC ACID ESTER
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A method for continuously preparing a carboxylic acid ester is disclosed. In the method of the present invention, a vertical reactor is filled with a solid catalyst, a carboxylic acid and an alcohol are introduced into a lower part of the vertical reactor, esterification is performed to form an esterized mixture, the esterized mixture is output from an upper part of the vertical reactor, and distillation is performed to isolate the carboxylic acid ester. The method of the present invention is simple, easily controlled and environmental friendly, and has significantly high conversion rate and selectivity.
- -
-
Paragraph 0033; 0034
(2013/11/19)
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- Selective hydrogenation of alkynes catalyzed by trinuclear rhodium hydride complexes of the type [{(Rh[PP]H)3(μ2-H)3(μ3-H)}(BF4)2]
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A clean win: A novel trinuclear rhodium(III)-hydride species allows for highly selective hydrogenation of diarylacetylenes under mild conditions (1bar of hydrogen pressure at 30.0°C in methanol) with low catalyst loadings (substrate/catalyst molar ratio≤10000). In contrast to the mononuclear complex of the type [{Rh(PPz.ast;)(MeOH)2}BF4], no overhydrogenation of the diphenylacetylene to the alkane is observed. The hydrogen consumption follows Michaelis-Menten kinetics.
- Kohrt, Christina,Wienhoefer, Gerrit,Pribbenow, Cornelia,Beller, Matthias,Heller, Detlef
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p. 2818 - 2821
(2013/10/21)
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- Ruthenium(II) complexes bearing a ligand derived from P, N - Or P, N, O-diphenylphosphinobenzoxazine: Synthesis, X-ray characterization, and cis diastereoselectivity in styrene cyclopropanation
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A phosphino-oxazine based ligand (L; 2-(2-(diphenylphosphino)phenyl)-2,4- dihydro-1H-benzo[d][1,3]oxazine) showing a temperature-dependent equilibrium between a closed bidentate (LPN) and an opened tridentate (L PNO) form, has been synthesized and its coordination behavior toward ruthenium(II) centers studied. Under different experimental conditions, two different species bearing the ligand in either its bidentate or tridentate coordination mode were isolated by reaction with Ru(PPh3) 3Cl2. These species, respectively formulated as [Ru(PPh3)(LPNO)Cl2] (1) and [Ru(PPh 3)(LPN)Cl2] (2), were fully characterized via NMR in solution and by an X-ray structural determination. Notably, compound 2 reacts with an excess of ethyl diazoacetate (EDA) in CH2Cl 2 to give a stable η3-diethyl maleate complex, [Ru(LPN)(cis-EtO(O)CCH=CHC(O)OEt)Cl2] (3). The crystal structure of 3 has also been determined. Substitution reactions with 4-picoline (4-Me-py) performed on 1 led to two new complexes: the neutral complex [Ru(4-Me-py)(LPNO)Cl2] (5) and the salt [Ru(4-Me-py) 2(LPNO)Cl](Cl) (6a). The latter compound catalyzed the intermolecular cyclopropanation of styrene with EDA in high yields and with elevated cis diastereoselectivity (i.e., cis/trans = 80/20).
- Ardizzoia, G. Attilio,Brenna, Stefano,Durini, Sara,Therrien, Bruno
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p. 5427 - 5437
(2012/11/13)
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- Polynuclear copper(I) complexes with chelating bis- and tris-N-heterocyclic carbene ligands: Catalytic activity in nitrene and carbene transfer reactions
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Di- and trinuclear complexes of copper(I) bearing bis- or tris-N-heterocyclic carbene ligands have been prepared and evaluated as catalysts in nitrene transfer reactions from PhI=NTs to unsaturated and saturated substrates (olefin aziridination and C-H bond amidation) and carbene transfer reactions from diazo compounds to olefins. The complexes exhibited moderate-to-high catalytic activity in both processes. The tosylamidation of C-H bonds, previously unreported with a NHC-containing copper catalyst, was promoted by the dinuclear complexes. Polynuclear oligo-NHC-copper complexes catalyse the transfer of carbene or nitrene fragments to unsaturated and saturated substrates. The first example of the tosylamidation of C-H bonds with a catalyst containing the NHCCu core is described. Copyright
- Tubaro, Cristina,Biffis, Andrea,Gava, Riccardo,Scattolin, Elena,Volpe, Andrea,Basato, Marino,Diaz-Requejo, M. Mar,Perez, Pedro J.
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experimental part
p. 1367 - 1372
(2012/04/11)
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- Rhodium catalyzed synthesis of isoindolinones via C-H activation of N-benzoylsulfonamides
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An efficient approach to a wide range of isoindolinones, including 3-monosubstituted and 3,3-disubstituted isoindolinones, from the annulation of N-benzoylsulfonamides with olefins and diazoacetate has been developed. The transformation is broadly compatible with both terminal and internal olefins. Moreover, diazoacetate is for the first time incorporated into an amide-directed C-H functionalization reaction. Specifically, the rhodium complex [{RhCl 2Cp*}2] enables the in situ dimerization of diazoacetate in addition to its role in catalyzing C-H functionalization/cross- coupling.
- Zhu, Chen,Falck, John R.
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p. 9192 - 9199
(2012/10/29)
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- Hydrotris(3-mesitylpyrazolyl)borato-copper(i) alkyne complexes: Synthesis, structural characterization and rationalization of their activities as alkyne cyclopropenation catalysts
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The use of the bulky hydrotris(3-mesitylpyrazolyl)borate anionic ligand has allowed the synthesis of stable TpMsCu(alkyne) complexes (alkyne = 1-hexyne, 1, phenylacetylene, 2, and ethyl propiolate, 3). The spectroscopic and structural features of these compounds and their relative reactivity have been examined, indicating the existence of a low π back-bonding from the copper(i) centre to the alkyne. Ligand exchange experiments have shown that terminal alkyne adducts are more stable than internal alkyne analogues. In good accordance with this, the previously reported alkyne cyclopropenation reaction catalysed by the TpxCu complexes can be rationalized and correlated with their relative stability.
- Martin, Carmen,Sierra, Marta,Alvarez, Eleuterio,Belderrain, Tomas R.,Perez, Pedro J.
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experimental part
p. 5319 - 5325
(2012/05/20)
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- Enantioselective cyclopropanation of indoles: Construction of all-carbon quaternary stereocenters
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The first enantioselective copper-catalyzed cyclopropanation of N-acyl indoles is described. Using carbohydrate-based bis(oxazoline) ligands (glucoBox), the products were obtained in up to 72% ee. Cyclopropanation of N-Boc 3-methyl indole yielded a product with an all-carbon quaternary stereocenter, which is a valuable building block for the synthesis of indole alkaloids: Deprotection and rearrangement gave a tricyclic hemiaminal ester in 96% ee, which was subsequently employed as a key intermediate for the synthesis of (-)-desoxyeseroline.
- ?züduru, Gülsüm,Schubach, Thea,Boysen, Mike M. K.
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supporting information
p. 4990 - 4993
(2013/01/15)
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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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- Site-directed anchoring of an N-heterocyclic carbene on a dimetal platform: Evaluation of a pair of diruthenium(i) catalysts for carbene-transfer reactions from ethyl diazoacetate
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Site-directed anchoring of naphthyridine-functionalized N-heterocylic carbene (NHC) is achieved on a metal-metal singly bonded diruthenium(I) platform. Room-temperature treatment of 1-isopropyl-3-(5,7-dimethyl-1,8- naphthyrid-2-yl)imidazolium bromide (PINA·HBr) with Ru 2(CH3COO)2(CO)4 in acetonitrile affords the unsupported compound Ru2(CO) 4(μ2C2,N1-PIN)2Br 2 (1). Judicious alteration in the NHC ligand resulted in the bridged compound Ru2(CO)4(CH3COO)(μ2- μ2C2,N1-BIN)Br (2) (BIN = 1-benzyl-3-(3-phenyl-1,8-naphthyrid-2-yl)imidazol-2-ylidene). X-ray analysis revealed the chelate binding of PIN on each ruthenium at equatorial sites for 1, and the bridge-chelate binding of BIN spanning the diruthenium core for 2. The catalytic utilities of the BArF (tetrakis(3,5-bis(trifluoromethyl) phenyl)borate) salts of these compounds are evaluated toward carbene-transfer reactions from ethyl diazoacetate including aldehyde olefination, cyclopropanation, and X-H (X = O, N) insertions. 1-BArF is clearly shown to be the superior catalyst. DFT calculations are undertaken to understand the influence of NHC binding on the electronic structures of the "Ru 2(CO)4" core and to rationalize the lower activity of 2-BArF.
- Saha, Biswajit,Ghatak, Tapas,Sinha, Arup,Rahaman, S. M. Wahidur,Bera, Jitendra K.
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body text
p. 2051 - 2058
(2011/06/18)
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- Silver-catalyzed C-C bond formation between methane and ethyl diazoacetate in supercritical CO2
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Even in the context of hydrocarbons' general resistance to selective functionalization, methane's volatility and strong bonds pose a particular challenge. We report here that silver complexes bearing perfluorinated indazolylborate ligands catalyze the reaction of methane (CH4) with ethyl diazoacetate (N2CHCO2Et) to yield ethyl propionate (CH3CH2CO2Et). The use of supercritical carbon dioxide (scCO2) as the solvent is key to the reaction's success. Although the catalyst is only sparingly soluble in CH4/CO2 mixtures, optimized conditions presently result in a 19% yield of ethyl propionate (based on starting quantity of the diazoester) at 40°C over 14 hours.
- Caballero, Ana,Despagnet-Ayoub, Emmanuelle,Diaz-Requejo, M. Mar,Diaz-Rodriguez, Alba,Gonzalez-Nunez, Maria Elena,Mello, Rossella,Munoz, Bianca K.,Ojo, Wilfried-Solo,Asensio, Gregorio,Etienne, Michel,Perez, Pedro J.
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scheme or table
p. 835 - 838
(2011/12/03)
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- Exclusive aromatic vs aliphatic C-H bond functionalization by carbene insertion with gold-based catalysts
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The direct functionalization of aromatic C-H bonds by carbene insertion from diazo compounds catalyzed by gold complexes with N-heterocyclic ligands is described. The reaction is completely selective toward the C sp2-H bonds, other C sp3-H bonds remaining unreacted. A study with several NHC ligands in Au(I) and Au(III) complexes has been performed. The potential application of this strategy to give profen derivatives has also been explored.
- Rivilla, Ivan,Gomez-Emeterio, B. Pilar,Fructos, Manuel R.,Diaz-Requejo, M. Mar,Perez, Pedro J.
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experimental part
p. 2855 - 2860
(2011/07/08)
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- Highly selective iron-catalyzed synthesis of alkenes by the reduction of alkynes
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Herein, the iron-catalyzed reduction of a variety of alkynes with silanes as a reductant has been examined. With a straightforward catalyst system composed of diiron nonacarbonyl and tributyl phosphane, excellent yields and chemoselectivities (>99 %) were obtained for the formation of the corresponding alkenes. After studying the reaction conditions, and the scope and limitations of the reaction, several attempts were undertaken to shed light on the reaction mechanism. Im Rahmen dieser Arbeit wird die Eisen-katalysierte Reduktion von Alkinen zu den entsprechenden Alkenen mit Hilfe von Silanen vorgestellt. Hierbei konnten exzellente Ausbeuten und Selektivitaeten (>99 %) durch die Modifikation des eingesetzten Eisenkatalysators mit Phosphanen beobachtet werden. Nach genauer Untersuchung verschiedenster Reaktionsparameter wurden die hervorragenden Eigenschaften des Katalysatorsystems in der Reduktion zahlreicher Alkine gezeigt. Zum besseren Verstaendnis der Reaktion wurden verschiedene mechanistische Experimente durchgefuehrt. Iron Made′m: In situ generated iron complexes catalyze the reduction of alkynes with silanes as a hydride source with excellent selectivity (>99 %). Copyright
- Enthaler, Stephan,Haberberger, Michael,Irran, Elisabeth
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experimental part
p. 1613 - 1623
(2012/06/04)
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