- EFFECTS OF LIGANDS ON ION-PAIRING BEHAVIOR OF BENZYLIC LITHIUM COMPOUNDS
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The 1/1/ adduct of t-butyllithium and α-methylstyrene (II) has been generated in cyclopentane in the presence of a variety of ether and t-amine ligands as well as unsolvated, giving stable solutions in every case.NMR spectra of the solvated species are the same for all ligands but differ from that of the unsolvated compound.The results are consistent with a salt which contains a conjugated t-benzylic anion and exists as a loose ion-pair in the presence of ligands and as a tight ion-pair in cyclopentane alone.In contrast, benzyllithium behaves like a tight ion-pair in the presence of all ligands tried.Steric hindrance to tight ion-pairing at Cα of II is concluded to be responsible for the results observed.A covalently-bonded dilithium compound, 4,4-dimethyl-2-lithio-2-(p-lithio-phenyl)pentane has been generated.
- Fraenkel, Gideon,Geckle, Michael J.,Kaylo, Allan,Estes, Don W.
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Read Online
- D0Metal-Catalyzed Alkyl-Alkyl Cross-Coupling Enabled by a Redox-Active Ligand
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Alkyl-alkyl cross-coupling through well-defined mechanisms that allow for controlled oxidative addition, prevent β-hydride elimination, and tolerate hindered electrophiles is still challenging. Described herein is a redox-active ligand-enabled alkyl-alkyl cross-coupling using a d0 metal. This tris(amido) ScIII complex as well as the oxidized variant have been thoroughly characterized (NMR, X-ray, EPR, CV, UV-vis, DFT). Insight into the likely radical nature of the mechanism is disclosed. Additionally, a substrate scope that includes functional groups incompatible with late-transition-metal catalysis and both coupling partners bearing β-hydrogens is reported.
- Belli, Roman G.,Joannou, Matthew V.,Roberts, Courtney C.,Tafuri, Victoria C.
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p. 3094 - 3099
(2022/03/15)
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- Reductive activation and hydrofunctionalization of olefins by multiphoton tandem photoredox catalysis
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The conversion of olefin feedstocks to architecturally complex alkanes represents an important strategy in the expedient generation of valuable molecules for the chemical and life sciences. Synthetic approaches are reliant on the electrophilic activation of unactivated olefins, necessitating functionalization with nucleophiles. However, the reductive functionalization of unactivated and less activated olefins with electrophiles remains an ongoing challenge in synthetic chemistry. Here, we report the nucleophilic activation of inert styrenes through a photoinduced direct single electron reduction to the corresponding nucleophilic radical anion. Central to this approach is the multiphoton tandem photoredox cycle of the iridium photocatalyst [Ir(ppy)2(dtbbpy)] PF6, which triggers in situ formation of a high-energy photoreductant that selectively reduces styrene olefinic π bonds to radical anions without stoichiometric reductants or dissolving metals. This mild strategy enables the chemoselective reduction and hydrofunctionalization of styrenes to furnish valuable alkane and tertiary alcohol derivatives. Mechanistic studies support the formation of a styrene olefinic radical anion intermediate and a Birch-type reduction involving two sequential single electron transfers. Overall, this complementary mode of olefin activation achieves the hydrofunctionalization of less activated alkenes with electrophiles, adding value to abundant olefins as valuable building blocks in modern synthetic protocols.
- Czyz, Milena L.,Taylor, Mitchell S.,Horngren, Tyra H.,Polyzos, Anastasios
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p. 5472 - 5480
(2021/06/01)
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- Nickel-catalyzed reductive deoxygenation of diverse C-O bond-bearing functional groups
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We report a catalytic method for the direct deoxygenation of various C-O bond-containing functional groups. Using a Ni(II) pre-catalyst and silane reducing agent, alcohols, epoxides, and ethers are reduced to the corresponding alkane. Unsaturated species including aldehydes and ketones are also deoxygenated via initial formation of an intermediate silylated alcohol. The reaction is chemoselective for C(sp3)-O bonds, leaving amines, anilines, aryl ethers, alkenes, and nitrogen-containing heterocycles untouched. Applications toward catalytic deuteration, benzyl ether deprotection, and the valorization of biomass-derived feedstocks demonstrate some of the practical aspects of this methodology.
- Cook, Adam,MacLean, Haydn,St. Onge, Piers,Newman, Stephen G.
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p. 13337 - 13347
(2021/11/20)
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- Cobalt-Catalyzed Hydrogenations via Olefin Cobaltate and Hydride Intermediates
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Redox noninnocent ligands are a promising tool to moderate electron transfer processes within base-metal catalysts. This report introduces bis(imino)acenaphthene (BIAN) cobaltate complexes as hydrogenation catalysts. Sterically hindered trisubstituted alkenes, imines, and quinolines underwent clean hydrogenation under mild conditions (2-10 bar, 20-80 °C) by use of the stable catalyst precursor [(DippBIAN)CoBr2] and the cocatalyst LiEt3BH. Mechanistic studies support a homogeneous catalysis pathway involving alkene and hydrido cobaltates as active catalyst species. Furthermore, considerable reaction acceleration by alkali cations and Lewis acids was observed. The dinuclear hydridocobaltate anion with bridging hydride ligands was isolated and fully characterized.
- Sandl, Sebastian,Maier, Thomas M.,Van Leest, Nicolaas P.,Kr?ncke, Susanne,Chakraborty, Uttam,Demeshko, Serhiy,Koszinowski, Konrad,De Bruin, Bas,Meyer, Franc,Bodensteiner, Michael,Herrmann, Carmen,Wolf, Robert,Von Jacobi Wangelin, Axel
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p. 7596 - 7606
(2019/08/20)
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- Iridium-Catalyzed Alkene-Selective Transfer Hydrogenation with 1,4-Dioxane as Hydrogen Donor
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The iridium-catalyzed transfer hydrogenation of alkenes using 1,4-dioxane as a hydrogen donor is described. The use of 1,2-bis(dicyclohexylphosphino)ethane (DCyPE), featuring bulky and highly electron-donating properties, led to high catalytic activity. A polystyrene-cross-linking bisphosphine PS-DPPBz produced a reusable heterogeneous catalyst. These homogeneous and heterogeneous protocols achieved chemoselective transfer hydrogenation of alkenes over other potentially reducible functional groups such as carbonyl, nitro, cyano, and imino groups in the same molecule.
- Zhang, Deliang,Iwai, Tomohiro,Sawamura, Masaya
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supporting information
p. 5867 - 5872
(2019/08/26)
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- Olefin-Stabilized Cobalt Nanoparticles for C=C, C=O, and C=N Hydrogenations
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The development of cobalt catalysts that combine easy accessibility and high selectivity constitutes a promising approach to the replacement of noble-metal catalysts in hydrogenation reactions. This report introduces a user-friendly protocol that avoids complex ligands, hazardous reductants, special reaction conditions, and the formation of highly unstable pre-catalysts. Reduction of CoBr2 with LiEt3BH in the presence of alkenes led to the formation of hydrogenation catalysts that effected clean conversions of alkenes, carbonyls, imines, and heteroarenes at mild conditions (3 mol % cat., 2–10 bar H2, 20–80 °C). Poisoning studies and nanoparticle characterization by TEM, EDX, and DLS supported the notion of a heterotopic catalysis mechanism.
- Sandl, Sebastian,Schwarzhuber, Felix,P?llath, Simon,Zweck, Josef,Jacobi von Wangelin, Axel
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supporting information
p. 3403 - 3407
(2018/02/13)
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- STABILIZATION OF ACTIVE METAL CATALYSTS AT METAL-ORGANIC FRAMEWORK NODES FOR HIGHLY EFFICIENT ORGANIC TRANSFORMATIONS
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Metal-organic framework (MOFs) compositions based on post?synthetic metalation of secondary building unit (SBU) terminal or bridging OH or OH2 groups with metal precursors or other post-synthetic manipulations are described. The MOFs provide a versatile family of recyclable and reusable single-site solid catalysts for catalyzing a variety of asymmetric organic transformations, including the regioselective boryiation and siiylation of benzyiic C—H bonds, the hydrogenation of aikenes, imines, carbonyls, nitroarenes, and heterocycles, hydroboration, hydrophosphination, and cyclization reactions. The solid catalysts can also be integrated into a flow reactor or a supercritical fluid reactor.
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Paragraph 0247; 0257
(2019/01/07)
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- Alkene Hydrogenations by Soluble Iron Nanocluster Catalysts
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The replacement of noble metal technologies and the realization of new reactivities with earth-abundant metals is at the heart of sustainable synthesis. Alkene hydrogenations have so far been most effectively performed by noble metal catalysts. This study reports an iron-catalyzed hydrogenation protocol for tri- and tetra-substituted alkenes of unprecedented activity and scope under mild conditions (1–4 bar H2, 20 °C). Instructive snapshots at the interface of homogeneous and heterogeneous iron catalysis were recorded by the isolation of novel Fe nanocluster architectures that act as catalyst reservoirs and soluble seeds of particle growth.
- Gieshoff, Tim N.,Chakraborty, Uttam,Villa, Matteo,Jacobi von Wangelin, Axel
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supporting information
p. 3585 - 3589
(2017/03/21)
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- Cyclohexa-1,3-diene-based dihydrogen and hydrosilane surrogates in B(C6F5)3-catalysed transfer processes
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The cyclohexa-1,3-diene motif is introduced as an equally effective alternative to the cyclohexa-1,4-diene platform in B(C6F5)3-catalysed transfer processes. The transfer hydrogenation of alkenes is realised with α-terpinene and the related transfer hydrosilylation is achieved with 5-trimethylsilyl-substituted cyclohexa-1,3-diene. Both yields and substrate scope are comparable with the prior systems.
- Yuan, Weiming,Orecchia, Patrizio,Oestreich, Martin
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supporting information
p. 10390 - 10393
(2017/09/25)
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- Metal-Organic Frameworks Stabilize Solution-Inaccessible Cobalt Catalysts for Highly Efficient Broad-Scope Organic Transformations
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New and active earth-abundant metal catalysts are critically needed to replace precious metal-based catalysts for sustainable production of commodity and fine chemicals. We report here the design of highly robust, active, and reusable cobalt-bipyridine- and cobalt-phenanthroline-based metal-organic framework (MOF) catalysts for alkene hydrogenation and hydroboration, aldehyde/ketone hydroboration, and arene C-H borylation. In alkene hydrogenation, the MOF catalysts tolerated a variety of functional groups and displayed unprecedentedly high turnover numbers of ~2.5 × 106 and turnover frequencies of ~1.1 × 105 h-1. Structural, computational, and spectroscopic studies show that site isolation of the highly reactive (bpy)Co(THF)2 species in the MOFs prevents intermolecular deactivation and stabilizes solution-inaccessible catalysts for broad-scope organic transformations. Computational, spectroscopic, and kinetic evidence further support a hitherto unknown (bpy?-)CoI(THF)2 ground state that coordinates to alkene and dihydrogen and then undergoing σ-complex-assisted metathesis to form (bpy)Co(alkyl)(H). Reductive elimination of alkane followed by alkene binding completes the catalytic cycle. MOFs thus provide a novel platform for discovering new base-metal molecular catalysts and exhibit enormous potential in sustainable chemical catalysis.
- Zhang, Teng,Manna, Kuntal,Lin, Wenbin
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supporting information
p. 3241 - 3249
(2016/03/19)
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- Br?nsted Acid-Catalyzed Transfer Hydrogenation of Imines and Alkenes Using Cyclohexa-1,4-dienes as Dihydrogen Surrogates
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Cyclohexa-1,4-dienes are introduced to Br?nsted acid-catalyzed transfer hydrogenation as an alternative to the widely used Hantzsch dihydropyridines. While these hydrocarbon-based dihydrogen surrogates do offer little advantage over established protocols in imine reduction as well as reductive amination, their use enables the previously unprecedented transfer hydrogenation of structurally and electronically unbiased 1,1-di- and trisubstituted alkenes. The mild procedure requires 5.0 mol % of Tf2NH, but the less acidic sulfonic acids TfOH and TsOH work equally well.
- Chatterjee, Indranil,Oestreich, Martin
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supporting information
p. 2463 - 2466
(2016/06/09)
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- B(C6F5)3-Catalyzed Transfer of Dihydrogen from One Unsaturated Hydrocarbon to Another
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A transition-metal-free transfer hydrogenation of 1,1-disubstituted alkenes with cyclohexa-1,4-dienes as the formal source of dihydrogen is reported. The process is initiated by B(C6F5)3-mediated hydride abstraction from the dihydrogen surrogate, forming a Bronsted acidic Wheland complex and [HB(C6F5)3]-. A sequence of proton and hydride transfers onto the alkene substrate then yields the alkane. Although several carbenium ion intermediates are involved, competing reaction channels, such as dihydrogen release and cationic dimerization of reactants, are largely suppressed by the use of a cyclohexa-1,4-diene with methyl groups at the C1 and C5 as well as at the C3 position, the site of hydride abstraction. The alkene concentration is another crucial factor. The various reaction pathways were computationally analyzed, leading to a mechanistic picture that is in full agreement with the experimental observations.
- Chatterjee, Indranil,Qu, Zheng-Wang,Grimme, Stefan,Oestreich, Martin
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supporting information
p. 12158 - 12162
(2015/10/12)
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- Synthesis and hydrogenation activity of iron dialkyl complexes with chiral bidentate phosphines
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The activity of bis(phosphine) iron dialkyl complexes for the asymmetric hydrogenation of alkenes has been evaluated. High-throughput experimentation was used to identify suitable iron-phosphine combinations using the displacement of pyridine from py2Fe(CH2SiMe3)2 for precatalyst formation. Preparative-scale synthesis of a family of bis(phosphine) iron dialkyl complexes was also achieved using both ligand substitution and salt metathesis methods. Each of the isolated organometallic iron complexes was established as a tetrahedral and hence high-spin ferrous compound, as determined by M?ssbauer spectroscopy, magnetic measurements, and, in many cases, X-ray diffraction. One example containing a Josiphos-type ligand, (SL-J212-1)Fe(CH2SiMe3)2, proved more active than other isolated iron dialkyl precatalysts. Filtration experiments and the lack of observed enantioselectivity support dissociation of the phosphine ligand upon activation with dihydrogen and formation of catalytically active heterogeneous iron. The larger six-membered chelate is believed to reduce the coordination affinity of the phosphine for the iron center, enabling metal particle formation.
- Hoyt, Jordan M.,Shevlin, Michael,Margulieux, Grant W.,Krska, Shane W.,Tudge, Matthew T.,Chirik, Paul J.
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p. 5781 - 5790
(2015/02/19)
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- Catalytic hydrogenation activity and electronic structure determination of bis(arylimidazol-2-ylidene)pyridine Cobalt Alkyl and Hydride Complexes
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The bis(arylimidazol-2-ylidene)pyridine cobalt methyl complex, ( iPrCNC)CoCH3, was evaluated for the catalytic hydrogenation of alkenes. At 22 C and 4 atm of H2 pressure, ( iPrCNC)CoCH3 is an effective precatalyst for the hydrogenation of sterically hindered, unactivated alkenes such as trans-methylstilbene, 1-methyl-1-cyclohexene, and 2,3-dimethyl-2-butene, representing one of the most active cobalt hydrogenation catalysts reported to date. Preparation of the cobalt hydride complex, (iPrCNC)CoH, was accomplished by hydrogenation of (iPrCNC)CoCH3. Over the course of 3 h at 22 C, migration of the metal hydride to the 4-position of the pyridine ring yielded (4-H2-iPrCNC)CoN2. Similar alkyl migration was observed upon treatment of (iPrCNC)CoH with 1,1-diphenylethylene. This reactivity raised the question as to whether this class of chelate is redox-active, engaging in radical chemistry with the cobalt center. A combination of structural, spectroscopic, and computational studies was conducted and provided definitive evidence for bis(arylimidazol-2- ylidene)pyridine radicals in reduced cobalt chemistry. Spin density calculations established that the radicals were localized on the pyridine ring, accounting for the observed reactivity, and suggest that a wide family of pyridine-based pincers may also be redox-active.
- Yu, Renyuan Pony,Darmon, Jonathan M.,Milsmann, Carsten,Margulieux, Grant W.,Stieber, S. Chantal E.,Debeer, Serena,Chirik, Paul J.
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supporting information
p. 13168 - 13184
(2013/09/24)
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- COBALT PHOSPHINE ALKYL COMPLEXES FOR THE ASYMMETRIC HYDROGENATION OF ALKENES
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Disclosed herein are manganese, iron, nickel, or cobalt compounds having a bidentate ligand and the use of these compounds for the hydrogenation of alkenes, particularly the asymmetric hydrogenation of prochiral olefins.
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Paragraph 0134
(2013/11/05)
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- Enantiopure C1-symmetric bis(imino)pyridine cobalt complexes for asymmetric alkene hydrogenation
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Enantiopure C1-symmetric bis(imino)pyridine cobalt chloride, methyl, hydride, and cyclometalated complexes have been synthesized and characterized. These complexes are active as catalysts for the enantioselective hydrogenation of geminal-disubstituted olefins.
- Monfette, Sebastien,Turner, Zoe R.,Semproni, Scott P.,Chirik, Paul J.
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supporting information; experimental part
p. 4561 - 4564
(2012/04/23)
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- The positional and structural izomerization equilibrium of branched pentylbenzenes
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The equilibrium of the positional and structural isomerization of branched monopentylbenzenes, pentyltoluenes, and pentyl-o-xylenes was studied. It was found that the 1,2-dimethylpropyl substituted derivatives prevail over the 1,1-dimethylpropyl substituted isomers in the equilibrium mixture of all of the examined groups of compounds. The thermodynamic characteristics of the structural isomerization of pentylbenzenes were calculated from the experimental data.
- Naumkin,Nesterova,Nesterov,Vodenkova,Golovin
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experimental part
p. 141 - 148
(2011/08/05)
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- Protodeboronation of tertiary boronic esters: Asymmetric synthesis of tertiary alkyl stereogenic centers
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While tertiary boranes undergo efficient protodeboronation with carboxylic acids, tertiary boronic esters do not. Instead, we have discovered that CsF with 1.1 equiv of H2O (on tertiary diarylalkyl boronic esters) or TBAF?3H2O (on tertiary aryldialkyl boronic esters) effect highly efficient protodeboronation of tertiary boronic esters with essentially complete retention of configuration. Furthermore, substituting D2O for H2O provides ready access to deuterium-labeled enantioenriched tertiary alkanes. The methodology has been applied to a short synthesis of the sesquiterpene, (S)-turmerone.
- Nave, Stefan,Sonawane, Ravindra P.,Elford, Tim G.,Aggarwal, Varinder K.
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supporting information; experimental part
p. 17096 - 17098
(2011/03/01)
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- Hydrogenation of C-C multiple bonds mediated by [Pd(NHC)(PCy3)] (NHC = N-heterocyclic carbene) under mild reaction conditions
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A study was conducted to demonstrate the behavior of a Pd 0-N-heterocyclic carbene (NHC) complex under hydrogen (H2) and its catalytic performance in hydrogenation of C-C multiple bonds. It was also demonstrated that [Pd(SIPr)(PCy3) solution was a highly active catalyst for the hydrogenation of a wide range of alkenes and alkynes using H2. It was observed that [Pd(SIPr)(PCy 3) underwent an oxidative addition, leading to the trans-dihydride species [Pd(H2)(SIPr))(PCy3). The presence of the species was also supported by1H NMR spectroscopy investigations. It was also demonstrated that the catalytic system was efficient for functionalized and non-functionalized terminal and internal alkenes.
- Jurcik, Vaclav,Nolan, Steven P.,Cazin, Catherine S. J.
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supporting information; experimental part
p. 2509 - 2511
(2009/11/30)
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- Efficient synthesis of amylbenzenes over zeolite catalysts
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The liquid-phase heterogeneous alkylation of benzene with 2-methyl-2-butene takes place actively and selectively over large-pore zeolite catalysts, which implies an environmentally friendly route for the synthesis of fert-amylbenzene. Copyright
- Zhang, Huanyan,Liu, Yueming,Wu, Haihong,Jiang, Yongwen,He, Mingyuan,Wu, Peng
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p. 138 - 139
(2007/10/03)
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- Synthesis of (R)-2-diphenylphosphino-2′-diphenylphosphinomethyl-1,1′-binaphthyl and its use for asymmetric hydrogenation of α-alkylstyrenes
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A new chiral bisphosphine ligand ((R)-2-diphenylphosphino-2′-diphenylphosphinomethyl-1,1′-binaphthyl) was synthesized from enantiomerically pure (R)-1,1′-binaphthalene-2,2′-diol. Rhodium(I) complexes of this bisphosphine ligand have been used as catalysts for asymmetric hydrogenation of α-alkylstyrenes to give the corresponding aromatic hydrocarbons in up to 77% ee.
- Inagaki, Kohji,Ohta, Tetsuo,Nozaki, Kyoko,Takaya, Hidemasa
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p. 159 - 163
(2007/10/03)
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- Use of Catalytic Systems Based on Aluminum Chloride in Alkylation of Benzene
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Catalytic action of supported catalysts AlCl3-MeX/SiO2, where MeX is a salt of a metal with variable valence, in alkylation of benzene with isoamyl bromide is studied for various temperatures and contact times. Binary catalytic systems are more active (with respect to the yield of amylbenzenes) than straight SiO2-supported catalysts. To a certain extent, the catalytic activity of binary systems is due to the presence of modifiers: water of crystallization and alkyl halides. The support influences the activity and selectivity of the catalysts owing to interaction between the components. Supported catalysts AlCl3-MeX/SiO2 surpass AlCl3 in selectivity and the yield of target products and suppress side processes that accompany alkylation. A mechanism is proposed for alkylation of benzene with isoamyl bromide on the catalysts prepared.
- Polubentseva,Duganova,Mikhailenko
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p. 607 - 613
(2007/10/03)
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- ALKYLATION NON CONVENTIONNELLE DE FRIEDEL ET CRAFTS DES AROMATIQUES PAR LES ISO ET CYCLOALCANES INDUITE PAR LES CHLORURES-SELECTIVITE ET OPTIMISATION
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Friedel-Crafts alkylation of benzene by C5-C8 isoalkanes induced by tert-butyl chloride affords good yields in the presence of small amounts of AlCl3.The isomeric alkylbenzenes prepared by hydride transfer are similar to those obtained by direct alkylation from the corresponding equivalent alcohols and chlorides.The kinetic tertiary alkyl benzene rearranges to a more stable secondary isomer ; the formation of isomers discussed.Fragmentation of isoalkanes (when any) is very small except with isooctane which gives only a tert-butyl-cation.The reaction may be extended to toluene, chlorobenzene and dichlorobenzene with no major change in selectivity i.e. trans vs direct alkylation.An optimization of the reaction using dichlorobenzene increases significantly conversion and selectivity in trans-alkylation product and stresses the importance of low temperature (ca. 40 deg C) and small amounts of catalyst.
- Iraqi, A.,Gallo, R.,Phan Tan Luu, R.
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p. 548 - 554
(2007/10/02)
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- MECHANISM OF INTRAMOLECULAR CYCLOALKYLATION OF 3-METHYL-3-PHENYL-1-BUTANOL IN THE PRESENCE OF D3PO4
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The intramolecular cycloalkylation of isomeric 2-methyl-4-phenyl-2-butanol and 3-methyl-3-phenyl-1-butanol in D3PO4 is accompanied by hydrogen exchange with the formation of deuterated 1,1-dimethylindane.The distribution of the deuterium in the polymethylene ring shows that the reaction of the first alcohol takes place as a result of C5-cyclization of the χ-phenylalkyl cation, whereas the reaction of the second alcohol takes place by direct C5-cyclization and by cyclization of the χ-phenylalkyl cations formed as a result of 1,2- and 1,3-transfers of the phenyl group.
- Sakhabutdinov, A. G.,Usmanova, A. G.,Frolov, P. A.,Kushnarev, D. F.,Schmidt, F. K.
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p. 1452 - 1455
(2007/10/02)
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- Alkyl Metal Asymmetric Reduction. 12. Optically Active Phenylalkanes from Organoaluminum Derivatives and Aliphatic Ketones
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The reaction of β-branched alkylaluminum dichloride with some aliphatic ketones has been studied in various solvents at room temperature.In benzene, the organoaluminum derivative rapidly reduces the ketone with formation of the alkoxyaluminum dichloride, which slowly alkylates the benzene to the corresponding phenylalkane.When optically active (2-methylbutyl)aluminum dichloride is used, both the carbinol from hydrolysis of the alkoxy aluminum species and the phenylalkane are optically active and of opposite absolute configuration.The overall results are also interpreted on the basis of previous findings, and a mechanism that accounts f or the formation of the optically active phenylalkanes is presented.
- Giacomelli, Giampaolo,Lardicci, Luciano
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p. 4335 - 4337
(2007/10/02)
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- NICKEL-CATALYZED STEREODIFFERENTIATING DISPLACEMENT REACTION BETWEEN PROCHIRAL 1-ALKENES AND OPTICALLY ACTIVE ORGANOALUMINIUM SOLVATES.
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The displacement reaction between optically active AlBui3 solvates and vinylidene alkenes, in the presence of Ni(mesal)2, affords optically active trialkylalanes and hence, upon hydrolysis or oxidative procedure, alkanes or 1-alkanols.
- Giacomelli, Giampaolo,Bertero, Luigi,Lardicci, Luciano
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p. 883 - 886
(2007/10/02)
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- Formylation and Acylation Reactions Catalysed by Trifluoromethanesulphonic Acid
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Regioselective formylation of toluene, m- and p-xylene, and mesitylene has been achieved by carbonylation in trifluoromethanesulphonic acid at CO pressures of 90-125 atm.In the case of cumene, the formylation reaction is in competition with disproportionation to form di- and tri-isopropylbenzenes, leading to a complex product mixture.Slow addition of cyclohexene or cyclopentene to a mixture of benzene and CF3SO3H under a high CO pressure affords 4-cyclohexylbenzaldehyde and 4-cyclopentylbenzaldehyde in 34percent and 33percent yieds, respectively, while 2-methylbut-1-ene gives 2,2,3-trimethylindanone (39percent) under similar conditions.When cyclohexene is mixed with the acid under carbon monoxide (120 atm) before addition of benzene the major products are cyclohexyl phenyl ketone and cyclohexenyl cyclohexyl ketones.
- Booth, Brian L.,El-Fekky, Teymour A.,Noori, Ghazi F. M.
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p. 181 - 186
(2007/10/02)
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