- Modular Ni(0)/Silane Catalytic System for the Isomerization of Alkenes
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Alkenes are used ubiquitously as starting materials and synthetic targets in all areas of chemistry. Controlling their geometry and position along a chain is vital to their reactivity and properties yet remains challenging. Alkene isomerization is an atom-economical process to synthesize targeted alkenes, and selectivity can be controlled using transition metal catalysts. The development of mild, selective isomerization reactivity has enabled efficient tandem catalytic systems for the remote functionalization of alkenes, a process in which a starting alkene is isomerized to a new position prior to the functionalization step. The key challenges in developing isomerization catalysts for remote functionalization applications are (i) a lack of modularity in the catalyst structure and (ii) the requirement of nonmodular and/or harsh additives during catalyst activation. We address both challenges with a modular (NHC)Ni(0)/silane catalytic system (NHC, N-heterocyclic carbene), demonstrating the use of triaryl silanes and readily accessible (NHC)Ni(0) complexes to form the proposed active (NHC)(silyl)Ni-H species in situ. We show that modification of the steric and electronic nature of the catalyst via modification of the ancillary ligand and silane partner, respectively, is easily achieved, creating a uniquely versatile catalytic system that is effective for the formation of internal alkenes with high yield and selectivity for the E-alkene. The use of silanes as mild activators enables isomerization of substrates with a variety of functional groups, including acid-labile groups. The broad substrate scope, enabled by catalyst design, makes this catalytic system a strong candidate for use in tandem catalytic applications. Preliminary mechanistic studies support a Ni-H insertion/elimination pathway.
- Chang, Alison Sy-Min,Cook, Amanda K.,Kawamura, Kiana E.,Martin, Daryl J.,Morris, Parker T.,Smith, Haley M.
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supporting information
p. 486 - 496
(2022/03/02)
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- Highly Z-Selective Double Bond Transposition in Simple Alkenes and Allylarenes through a Spin-Accelerated Allyl Mechanism
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Double-bond transposition in alkenes (isomerization) offers opportunities for the synthesis of bioactive molecules, but requires high selectivity to avoid mixtures of products. Generation of Z-alkenes, which are present in many natural products and pharmaceuticals, is particularly challenging because it is usually less thermodynamically favorable than generation of the E isomers. We report a β-dialdiminate-supported, high-spin cobalt(I) complex that can convert terminal alkenes, including previously recalcitrant allylbenzenes, to Z-2-alkenes with unprecedentedly high regioselectivity and stereoselectivity. Deuterium labeling studies indicate that the catalyst operates through a π-allyl mechanism, which is different from the alkyl mechanism that is followed by other Z-selective catalysts. Computations indicate that the triplet cobalt(I) alkene complex undergoes a spin state change from the resting-state triplet to a singlet in the lowest-energy C-H activation transition state, which leads to the Z product. This suggests that this change in spin state enables the catalyst to differentiate the stereodefining barriers in this system, and more generally that spin-state changes may offer a route toward novel stereocontrol methods for first-row transition metals.
- Kim, Daniel,Pillon, Guy,Diprimio, Daniel J.,Holland, Patrick L.
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supporting information
p. 3070 - 3074
(2021/03/08)
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- Switching the Reactivity of Palladium Diimines with “Ancillary” Ligand to Select between Olefin Polymerization, Branching Regulation, or Olefin Isomerization
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Coordinating solvents are commonly employed as ancillary ligands to stabilize late transition metal complexes and are conventionally considered to have little effect on the reaction products. Our work identifies that the presence of ancillary ligand in Pd-diimine catalyzed polymerizations of α-olefins can drastically alter reactivity. The addition of different amounts of acetonitrile allows for switching between distinct reaction modes: isomerization–polymerization with high branching (0 equiv.), regular chain-walking polymerization (1 equiv.), and alkene isomerization with no polymerization (>20 equiv.). Optimization of the isomerization reaction mode led to a general set of conditions to switch a wide variety of diimine complexes into efficient alkene isomerization catalysts, with catalyst loading as low as 0.005 mol %.
- Jones, Glen R.,Basbug Alhan, Hatice E.,Karas, Lucas J.,Wu, Judy I.,Harth, Eva
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supporting information
p. 1635 - 1640
(2020/11/30)
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- Selective Isomerization of Terminal Alkenes to (Z)-2-Alkenes Catalyzed by an Air-Stable Molybdenum(0) Complex
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Positional and stereochemical selectivity in the isomerization of terminal alkenes to internal alkenes is observed using the cis-Mo(CO)4(PPh3)2 precatalyst. A p-toluenesulfonic acid (TsOH) cocatalyst is essential for catalyst activity. Various functionalized terminal alkenes have been converted to the corresponding 2-alkenes, generally favoring the Z isomer with selectivity as high as 8:1 Z:E at high conversion. Interrogation of the catalyst initiation mechanism by 31P NMR reveals that cis-Mo(CO)4(PPh3)2 reacts with TsOH at elevated temperatures to yield a phosphine-ligated Mo hydride (MoH) species. Catalysis may proceed via 2,1-insertion of a terminal alkene into a MoH group and stereoselective β-hydride elimination to yield the (Z)-2-alkene.
- Becica, Joseph,Glaze, Owen D.,Wozniak, Derek I.,Dobereiner, Graham E.
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p. 482 - 490
(2018/02/17)
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- Normal Alpha Olefin Synthesis Using Metathesis and Dehydroformylation
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The present invention discloses processes for producing normal alpha olefins, such as 1-hexene, 1-octene, and 1-decene, in a multistep synthesis scheme. Generally, a first normal alpha olefin is subjected to an olefin metathesis step to form a linear internal olefin, which is then subjected to an isomerization-hydroformylation step to form a linear aldehyde, which is then subjected to a dehydroformylation step to form a second normal alpha olefin.
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- Careful investigation of the hydrosilylation of olefins at poly(ethylene glycol) chain ends and development of a new silyl hydride to avoid side reactions
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Hydrosilylation of olefin groups at poly(ethylene glycol) chain ends catalyzed by Karstedt catalyst often results in undesired side reactions such as olefin isomerization, hydrogenation, and dehydrosilylation. Since unwanted polymers obtained by side reactions deteriorate the quality of end-functional polymers, maximizing the hydrosilylation efficiency at polymer chain ends becomes crucial. After careful investigation of the factors that govern side reactions under various conditions, it was related that the short lifetime of the unstable Pt catalyst intermediate led to the formation of more side products under the inherently dilute conditions for polymers. Based on these results, two new chelating hydrosilylation reagents, tris(2-methoxyethoxy)silane (5) and 2,10-dimethyl-3,6,9-trioxa-2,10-disilaundecane (6), have been developed. It was demonstrated that the hydrosilylation efficiency at polymer chain ends was significantly increased by employing the internally coordinating hydrosilane 5. In addition, employment of the internally coordinating disilane species 6 in an addition polymerization with 1,5-hexadiene by hydrosilylation reaction yielded a polymer with high molecular weight (Mn = 9300 g/mol), which was significantly higher than that (Mn = 2600 g/mol) of the corresponding polymer obtained with non-chelating dihydrosilane, 1,1,3,3-tetramethyldisiloxane.
- Shin, Hyunseo,Moon, Bongjin
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p. 527 - 536
(2018/01/27)
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- CATALYSTS AND CATALYTIC PROCESSES
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A process for migrating C=C double bonds within an unsaturated organic compound is described. The process involves contacting an unsaturated organic compound starting material with a heteropoly acid catalyst in the presence of light having a wavelength of less than or equal to 700 nm. Also described is a process for the preparation of novel heteropoly acids having markedly increased surface area.
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Page/Page column 20
(2017/05/28)
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- An Agostic Iridium Pincer Complex as a Highly Efficient and Selective Catalyst for Monoisomerization of 1-Alkenes to trans-2-Alkenes
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A unique Ir complex (tBuNCCP)Ir with the pyridine–phosphine pincer as the sole ligand, featuring a dual agostic interaction between the Ir and two σ C?H bonds from a tBu substituent, has been prepared. This complex exhibits exceptionally high activity and excellent regio- and stereoselectivity for monoisomerization of 1-alkenes to trans-2-alkenes with wide functional-group tolerance. Reactions can be performed in neat reactant on a more than 100 gram scale using 0.005 mol % catalyst loadings with turnover numbers up to 19000.
- Wang, Yulei,Qin, Chuan,Jia, Xiangqing,Leng, Xuebing,Huang, Zheng
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supporting information
p. 1614 - 1618
(2017/02/05)
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- Fischer-Tropsch synthesis: effect of ammonia on product selectivities for a Pt promoted Co/alumina catalyst
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The effects of co-fed ammonia in synthesis gas on the activity and product selectivities of a typical cobalt catalyst (0.5% Pt-25% Co/Al2O3) were investigated during the Fischer-Tropsch synthesis using a continuously stirred tank reactor (CSTR). The product selectivities were compared at a similar CO conversion level for various concentrations (10-1000 ppmv) of ammonia, as well as clean (un-poisoned) conditions. The addition of 10-1000 ppmv ammonia (concentration of ammonia with respect to the syngas feed) significantly decreased activity; the percentage of deactivation was similar (~40%) for the various concentrations of ammonia used. At similar CO conversions, the addition of ammonia caused an increase in olefin selectivity and the corresponding paraffin and alcohol selectivities were decreased compared to the ammonia free synthesis conditions. Olefin selectivity increased with increasing concentration of ammonia, and the paraffin and alcohol selectivities were decreased with increasing ammonia concentration. At similar CO conversions, ammonia addition exhibited a positive effect on hydrocarbon selectivity (i.e., lower light gas products and higher C5+) and also light gas product selectivities (C1-C4) were decreased and C5+ selectivity increased with increasing concentration of ammonia compared to ammonia free conditions.
- Rao Pendyala, Venkat Ramana,Shafer, Wilson D.,Jacobs, Gary,Martinelli, Michela,Sparks, Dennis E.,Davis, Burtron H.
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p. 7793 - 7800
(2017/02/05)
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- Effect of the presence of ionic liquid during the NiMoS bulk preparation in the transformation of decanoic acid
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The impact of the presence and amount of [BMIM][NTf2] ionic liquid during the preparation of bulk NiMoS catalysts was investigated. It was clearly shown that these factors have a strong influence on both the morphology and specific surface area of the obtained NiMoS samples. Most interestingly the catalytic activity for the transformation of decanoic acid increased up to three times when IL was present during synthesis. In the same time, a greater selectivity towards hydrocarbons was observed. On the whole a clear relationship between catalytic activity, selectivity and NiMoS morphology was demonstrated. Consequently, it is possible to modify the morphology of the materials and impact the catalytic properties by changing the synthesis conditions.
- Leyral, Géraldine,Brillouet, Soizic,Rousseau, Julie,Richard, Frédéric,Mamede, Anne Sophie,Courthéoux, Laurence,Pradel, Annie,Ribes, Michel,Brunet, Sylvette
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p. 120 - 132
(2017/01/11)
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- Acid-catalysed carboxymethylation, methylation and dehydration of alcohols and phenols with dimethyl carbonate under mild conditions
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Dimethyl carbonate (DMC) chemistry has been extended to include acid-catalysed reactions of different aliphatic alcohols and phenols. For the first time, p-toluenesulfonic acid (PTSA), H2SO4, AlCl3 and FeCl3 have been shown to aid carboxymethylation for primary aliphatic alcohols at catalytic loadings with quantitative conversion and selectivity. For carboxymethylation of secondary alcohols, stoichiometric PTSA and catalytic AlCl3 both gave quantitative conversion and selectivity. Stoichiometric FeCl3 and H2SO4 promoted dehydration of linear aliphatic alcohols. Additionally FeCl3 catalysed methylation of cyclohexanol, whilst AlCl3 resulted in methylation of phenolic compounds. This research expands the range of potential application for DMC in green chemistry.
- Jin, Saimeng,Hunt, Andrew J.,Clark, James H.,McElroy, Con Robert
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supporting information
p. 5839 - 5844
(2016/11/06)
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- Double-Bond Isomerization: Highly Reactive Nickel Catalyst Applied in the Synthesis of the Pheromone (9 Z,12 Z)-Tetradeca-9,12-dienyl Acetate
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A highly reactive nickel catalyst comprising NiCl2(dppp) or NiCl2(dppe) with zinc powder, ZnI2 and Ph2PH, was applied in the isomerization of terminal alkenes to Z-2-alkenes. The double-bond geometry of the 2-alkene can be controlled via the reaction temperature to yield the 2-Z-alkenes in excellent yields and high Z-selectivities. The formation of other constitutional isomers, such as 3-alkenes, is suppressed on the basis of the proposed mechanism via a 1,2-hydride shift from the metal to the Ph2P ligand. The nickel-catalyzed isomerization reaction was then applied in the synthesis of (9Z,12Z)-tetradeca-9,12-dienyl acetate, a pheromone with a 2Z,5Z-diene subunit.
- Weber, Felicia,Schmidt, Anastasia,R?se, Philipp,Fischer, Michel,Burghaus, Olaf,Hilt, Gerhard
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supporting information
p. 2952 - 2955
(2015/06/30)
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- Anti-Markovnikov Hydroheteroarylation of Unactivated Alkenes with Indoles, Pyrroles, Benzofurans, and Furans Catalyzed by a Nickel-N-Heterocyclic Carbene System
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We report the catalytic addition of C-H bonds at the C2 position of heteroarenes, including pyrroles, indoles, benzofurans, and furans, to unactivated terminal and internal alkenes. The reaction is catalyzed by a combination of Ni(COD)2 and a sterically hindered, electron-rich N-heterocyclic carbene ligand or its analogous Ni(NHC)(arene) complex. The reaction is highly selective for anti-Markovnikov addition to α-olefins, as well as for the formation of linear alkylheteroarenes from internal alkenes. The reaction occurs with substrates containing ketones, esters, amides, boronate esters, silyl ethers, sulfonamides, acetals, and free amines.
- Schramm, York,Takeuchi, Makoto,Semba, Kazuhiko,Nakao, Yoshiaki,Hartwig, John F.
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supporting information
p. 12215 - 12218
(2015/10/12)
-
- PALLADIUM-CATALYZED DECARBONYLATION OF FATTY ACID ANHYDRIDES FOR THE PRODUCTION OF LINEAR ALPHA OLEFINS
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The present invention is directed to methods of forming olefins, especially linear alpha olefins from fatty acids or anhydrides, each method comprising: contacting an amount of precursor carboxylic acid anhydride with a palladium catalyst comprising a bidentate bis-phosphine ligand in a reaction mixture so as to form an olefin in a product with the concomittant formation and removal of CO and water from the reaction mixture, either directly or indirectly, wherein the reaction mixture is maintained with a sub-stoichiometric excess of a sacrificial carboxylic acid anhydride, an organic acid, or both, said sub-stoichiometric excess being relative to the amount of the precursor carboxylic acid anhydride. The precursor carboxylic acid anhydride may be added to the reaction mixture directly or formed in situ by the reaction between at least one precursor carboxylic acid with a stoichiometric amount of the sacrificial acid anhydride.
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Page/Page column
(2014/06/23)
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- Simple, chemoselective, catalytic olefin isomerization
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Catalytic amounts of Co(SaltBu,tBu)Cl and organosilane irreversibly isomerize terminal alkenes by one position. The same catalysts effect cycloisomerization of dienes and retrocycloisomerization of strained rings. Strong Lewis bases like amines and imidazoles, and labile functionalities like epoxides, are tolerated.
- Crossley, Steven W. M.,Barabé, Francis,Shenvi, Ryan A.
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supporting information
p. 16788 - 16791
(2015/01/09)
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- METHODS OF MAKING FUNCTIONALIZED INTERNAL OLEFINS AND USES THEREOF
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A method of isomerizing a substance includes combining a substance including a terminal alkenyl group and a substance including a fluorosulfonic acid group in a reaction mixture, and forming a substance including a 2-alkenyl group from the substance including a terminal alkenyl group in the reaction mixture. The method may be used to functionalize a substance, as the substance including a 2-alkenyl group can be reacted with a functionalizing agent to form a substance including a first functional group. The methods may be used to form a dicarboxylic acid, such as suberic acid, from a renewable feedstock.
- -
-
Paragraph 00147-00148
(2014/06/23)
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- Palladium-catalyzed decarbonylative dehydration of fatty acids for the production of linear alpha olefins
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A highly efficient palladium-catalyzed decarbonylative dehydration reaction of carboxylic acids is reported. This method transforms abundant and renewable even-numbered natural fatty acids into valuable and expensive odd-numbered alpha olefins. Additionally, the chemistry displays a high functional group tolerance. The process employs a low loading of palladium catalyst and proceeds under solvent-free and relatively mild conditions.
- Liu, Yiyang,Kim, Kelly E.,Herbert, Myles B.,Fedorov, Alexey,Grubbs, Robert H.,Stoltz, Brian M.
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supporting information
p. 130 - 136
(2014/03/21)
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- Trial for anti-markovnikov hydration of 1-decene using platinum complexes bearing a pbp pincer ligand, inducing alkene isomerization and decomposition of PBP ligand
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Mixing of [(PBP)PtCl] complex with 1-decene and H2O afforded isomerized alkenes. Deuterium-labeling experiment indicated the catalytically active hydride species for alkene isomerization formed from water and [(PBP)Pt] complex. Reaction of [(PBP)PtNTf2] with H2O gave a platinum hydride complex having PNNP ligand with a loss of boron atom, but the resulting complex showed low catalytic activity. Two types of cationic platinum hydride complexes were suggested as active species for alkene isomerization.
- Ogawa, Hayato,Yamashita, Makoto
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supporting information
p. 664 - 666
(2014/05/20)
-
- Solvent dependent reductive defluorination of aliphatic C-F bonds employing Sm(HMDS)2
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Sm(HMDS)2 in n-hexane mediates fast cleavage of primary, secondary and tertiary alkyl fluorides in good to excellent yields. In n-hexane Sm(HMDS)2 exhibits uniquely enhanced reductive ability towards the C-F bond compared to when using THF as solvent.
- Janjetovic, Mario,Tr?ff, Annika M.,Ankner, Tobias,Wettergren, Jenny,Hilmersson, G?ran
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supporting information
p. 1826 - 1828
(2013/03/29)
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- Selective semihydrogenation of alkynes on shape-controlled palladium nanocrystals
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A systematic study on the selective semihydrogenation of alkynes to alkenes on shape-controlled palladium (Pd) nanocrystals was performed. Pd nanocrystals with a cubic shape and thus exposed {100} facets were synthesized in an aqueous solution through the reduction of Na2PdCl4 with L-ascorbic acid in the presence of bromide ions. The Pd nanocubes were tested as catalysts for the semihydrogenation of various alkynes such as 5-decyne, 2-butyne-1,4-diol, and phenylacetylene. For all substrates, the Pd nanocubes exhibited higher alkene selectivity (>90 %) than a commercial Pd/C catalyst (75-90 %), which was attributed to a large adsorption energy of the carbon-carbon triple bond on the {100} facets of the Pd nanocubes. Our approach based on the shape control of Pd nanocrystals offers a simple and effective route to the development of a highly selective catalyst for alkyne semihydrogenation. Catalysis3: The semihydrogenation of various alkynes by Pd nanocubes was investigated. The nanocubes exhibited high alkene selectivity and complete cis-selectivity, thus surpassing the Lindlar catalyst. The shape control of Pd nanocrystals provides a simple and efficient way for generating highly selective catalysts for the semihydrogenation of alkynes.
- Chung, Jooyoung,Kim, Chanhoi,Jeong, Hansaem,Yu, Taekyung,Binh, Do Huy,Jang, Jyongsik,Lee, Jaichan,Kim, B. Moon,Lim, Byungkwon
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p. 919 - 925
(2013/08/25)
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- Stabilization of long-chain intermediates in solution. octyl radicals and cations
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The rearrangements of 1-octyl, 1-decyl and 1-tridecyl intermediates obtained from thermal lead(IV) acetate (LTA) decarboxylation of nonanoic, undecanoic and tetradecanoic acid were investigated experimentally through analysis and distribution of the products. The relationships between 1,5-, 1,6- and possibly existing 1,7-homolytic hydrogen transfer in 1-octyl-radical, as well as successive 1,2-hydride shift in corresponding cation have been computed via Monte-Carlo method. Taking into account that ratios of 1,5-/1,6-homolytic rearrangements in 1-octyl- and 1-tridecyl radical are approximately the same, the simulation shows very low involvement of 1,7-hydrogen rearrangement (1,5-/1,6-/1,7-hydrogen rearrangement = 85:31:1) in 1-octyl radical.
- Teodorovi?, Aleksandar V.,Badjuk, Dalibor M.,Stevanovi?, Nenad,Pavlovi?, Radoslav Z.
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- Enantioselective synthesis of tertiary and quaternary stereogenic centers: Copper/phosphoramidite-catalyzed allylic alkylation with organolithium reagents
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An efficient and highly enantioselective copper-catalyzed allylic alkylation of disubstituted allyl halides with primary and secondary organolithium reagents using phosphoramidite ligands is reported. The use of trisubstituted allyl bromides allows, for the first time, the enantioselective synthesis of all-carbon quaternary stereogenic centers with these reactive organometallic reagents.
- Fananas-Mastral, Martin,Perez, Manuel,Bos, Pieter H.,Rudolph, Alena,Harutyunyan, Syuzanna R.,Feringa, Ben L.
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supporting information; experimental part
p. 1922 - 1925
(2012/04/17)
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- Ti/Pd bimetallic systems for the efficient allylation of carbonyl compounds and homocoupling reactions
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The allylation, crotylation and prenylation of aldehydes and ketones with stable and easily handled allylic carbonates is promoted by a Ti/Pd catalytic system. This Ti/Pd bimetallic system is especially convenient for the allylation of ketones, which are infrequent substrates in other related protocols, and can be carried out intramolecularly to yield five- and six-membered cyclic products with good stereoselectivities. In addition, Ti/Pd-mediated reductions and Wuertz-type dimerisation reactions can be readily carried out from allyl carbonates and carboxylates.
- Millan, Alba,Campana, Araceli G.,Bazdi, Btissam,Miguel, Delia,Alvarez De Cienfuegos, Luis,Echavarren, Antonio M.,Cuerva, Juan M.
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experimental part
p. 3985 - 3994
(2011/05/07)
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- A selective Ru-catalyzed semireduction of alkynes to Z olefins under transfer-hydrogenation conditions
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By using a readily available, air- and moisture-stable dihydrido-Ru complex, a variety of Z olefins are accessible under transfer-hydrogenation conditions with formic acid as the hydrogen source in excellent yields and Z/E selectivities. A discerning transformation: Z-Configured C=C bonds are stereoselectively formed from alkynes in the presence of a Ru catalyst with formic acid as the sole H2 source at room temperature (see scheme). A variety of functional groups are compatible with this novel procedure. Operational simplicity and the lack of overreduction products are characteristics for this unprecedented process.
- Belger, Christian,Neisius, N. Matthias,Plietker, Bernd
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supporting information; experimental part
p. 12214 - 12220
(2011/03/17)
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- Liquid phase alkylation of benzene with dec-1-ene catalyzed on supported 12-tungstophosphoric acid
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The liquid phase alkylation of benzene with dec-1-ene was catalyzed by 12-tungstophosphoric acid (WP) supported on different solids (ZrO2, SiO2, activated carbon and boehmite-Al2O3). Catalysts prepared with 20 w
- Hernández-Cortez,Martinez,Soto,López,Navarrete,Manríquez,Lara,López-Salinas
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scheme or table
p. 346 - 352
(2010/08/06)
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- Hydrocarboxylation of terminal alkenes in supercritical carbon dioxide
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The catalytic hydrocarboxylation of linear alkenes to carboxylic acids using supercritical carbon dioxide as a solvent was studied. High selectivities in acids have been obtained. The best results were achieved when adding a perfluorinated surfactant to the reaction mixture (93% conversions and ca. 80% selectivity). Comparative multinuclear high-pressure NMR spectroscopic studies in [D8]THF and in supercritical CO2 show the formation of Pd0 species. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.
- Estorach, Clara Tortosa,Orejon, Arantxa,Ruiz, Nuria,Masdeu-Bulto, Anna M.,Laurenczy, Gabor
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experimental part
p. 3524 - 3531
(2009/02/07)
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- Cobalt-catalyzed cross-coupling reaction between functionalized primary and secondary alkyl halides and aliphatic Grignard reagents
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The coupling of primary and secondary unactivated alkyl bromides with alkyl-Grignard reagents was performed in good yields under mild conditions by using a new catalytic system: consisting of cobalt chloride and tetramethylethylenediamine (CoCl2·2 LiI, 4TMEDA). The reaction is very chemoselective since ketone, ester and nitrile functions are tolerated.
- Cahiez, Gerard,Chaboche, Christophe,Duplais, Christophe,Giulliani, Arianna,Moyeux, Alban
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supporting information; experimental part
p. 1484 - 1488
(2009/07/01)
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- Synthesis and catalytic activity of η1-allyl and η3-allyl, ethyl, and hydrido complexes of ruthenium- pentamethyl[60]fullerene
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η1-Allyl and η3-allyl, ethyl, and hydrido ruthenium complexes of pentamethyl[60]fullerene, Ru(η5-C 60Me5)R(CO)2 (R = η1-allyl, Et, H) and Ru(η5-C60Me5)(η3- allyl)(CO) were synthesized by the reaction of a chlorido complex Ru(η5-C60Me5)Cl(CO)2 with an allyl and an ethyl Grignard reagent or lithium aluminum hydride. Conversion of the η1-allyl complex to the corresponding η3-allyl complex and the catalytic performance of the hydrido and the chlorido complexes in the isomerization reaction of 1-decene to internal decenes are described. Wiley-VCH Verlag GmbH & Co. KGaA, 2007.
- Matsuo, Yutaka,Uematsu, Takashi,Nakamura, Eiichi
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p. 2729 - 2733
(2008/02/10)
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- Method of increasing the carbon chain length of olefinic compounds
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According to the present invention there is provided a process of increasing the carbon chain length of an olefinic compound comprising the steps of providing a starting olefinic compound and subjecting it to hydroformylation to produce an aldehyde and/or alcohol with an increased carbon chain length compared to the starting olefinic compound. Optionally, the aldehyde that may form during the hydroformylation reaction is hydrogenated to convert it to an alcohol which has an increased carbon chain length compared to the starting olefinic compound. The alcohol with the increased carbon chain length is subjected to dehydration to produce an olefinic compound with an increased carbon chain length compared to the starting olefinic compound. The invention also relates to olefinic compounds produced by the process.
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Page/Page column 3
(2008/06/13)
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- Reversal of regioselectivity in Wacker-Type oxidation of simple terminal alkenes and its paired interacting orbitals (PIO) analysis
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The trend of aldehyde selectivity observed in the oxidation of 1-decene with PdCl2(CH3CN)2/CuCl2 in alcohol (ROH) under O2 can be evaluated by the overlap populations for Pd-C and C-OR bonds in the oxypalladation step with paired interacting orbitals (PIO) analysis. The use of t-BuOH affords decanal in 84% regioselectivity.
- Ogura, Toshihiko,Kamimura, Ryuichiro,Shiga, Akinobu,Hosokawa, Takahiro
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p. 1555 - 1557
(2007/10/03)
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- Nickel-catalyzed cross-coupling reaction of alkyl halides with organozinc and grignard reagents with 1,3,8,10-tetraenes as additives
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Essential additives: The addition of bis(1,3-butadienyl) compounds (tetraenes) was essential in the efficient Nicatalyzed cross-coupling of organozinc reagents with alkyl bromides and a tosylate (see scheme, X = C(CO2Me)2 or NCH2Ph). The efficiency of the Ni-catalyzed cross-coupling of an alkyl fluoride with a Grignard reagent was also improved by using these tetraenes.
- Terao, Jun,Todo, Hirohisa,Watanabe, Hideyuki,Ikumi, Aki,Kambe, Nobuaki
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p. 6180 - 6182
(2007/10/03)
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- Ruthenium catalysts bearing N-heterocyclic carbene ligands in atom transfer radical reactions
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The catalytic activity of ruthenium-p-cymene complexes bearing N-heterocyclic carbene ligands in atom transfer radical addition (ATRA) or polymerisation (ATRP) strongly depends on the substituents of the carbene ligand, thereby providing a nice illustration of the importance of organometallic engineering and ligand fine tuning in homogeneous catalysis.
- Richel, Aurore,Delfosse, Sébastien,Cremasco, Cédric,Delaude, Lionel,Demonceau, Albert,Noels, Alfred F.
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p. 6011 - 6015
(2007/10/03)
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- PROCESS FOR THE PRODUCTION OF A WELL FLUIDS BASE OIL VIA METATHESIS OF ALPHA-OLEFINS
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Disclosed is a process for preparation of compositions having utility as well fluid base oils. The process involves metathesis of alpha-olefins followed by isomerization of the metathesis products. The base oils resulting from the process of this invention are environmentally friendly in that they are only mildly toxic to marine life, are highly biodegradable and have very low pour point temperatures. These properties make the base oils ideal candidates for use as components of well fluids for cold climates and offshore applications.
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- A new route of the reaction of EtAlCl2 with α-olefins catalyzed by Ti complexes
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A new method for the synthesis of dialkyl(ethyl)alanes by the reaction of EtAlCl2 with α-olefins in the presence of Mg and a catalytic amount of Cp2TiCl2 (Ti(OPri)4, Ti(OBun)4) in THF was developed.
- Ibragimov,Khafizova,Zagrebel'naya,Parfenova,Sultanov,Khalilov,Dzkemilev
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p. 292 - 296
(2007/10/03)
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- Molecular engineering in homogeneous catalysis: One-phase catalysis coupled with biphase catalyst separation. The fluorous-soluble HRh(CO){P[CH2CH2(CF2)5CF3]3}3 hydroformylation system
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The hydroformylation of decene-1 was studied in the presence of the fluorous-soluble P[CH2-CH2(CF2)5CF3]3 modified rhodium catalyst at 100 °C and 1.1 MPa of CO/H2 (1:1) in a 50/50 vol % toluene/C6F11CF3 solvent mixture, which forms a homogeneous liquid phase at and above 100 °C. P[CH2CH2(CF2)5CF3]3 was selected on the basis of a semiempirical calculation of the electronic properties of P[(CH2)(x)(CF2)(y)CF3]3 (x = 0, y = 2, 4 and x = 0-5, y = 2) and prepared by the reaction of PH3 with CH2=CH(CF2)5CF3. The solution structure of HRh(CO){P[CH2CH2(CF2)5CF3]3}3 (1) in C6F11CF3 is similar to that of HRh(CO)(PPh3)3 (2) in toluene and HRh(CO){P(m-C6H4SO3Na)3}3 (3) in water. High-pressure NMR of 1 under 2.1-8.3 MPa of CO/H2 (1:1) revealed that 1 is in equilibrium with HRh(CO)2{P[CH2CH2(CF2)5CF3]3}2 (4). Kinetic studies show that the reaction is first order in both rhodium and decene-1. While the reaction is inhibited by P[CH2-CH2(CF2)5CF3]3, the normal/iso (n/i) ratio of the aldehyde increases with increasing phosphine concentration. The catalytic activity of the Rh/P[CH2CH2(CF2)5CF3]3 catalyst is similar to that of the nonfluorous analogue Rh/P[(CH2)7CH3]3 catalyst and is an order of magnitude lower than that of the Rh/PPh3 catalyst. Surprisingly, the n/i product selectivity of Rh/P[CH2CH2(CF2)5CF3]3 is closer to the selectivity of the Rh/PPh3 catalyst than that of the Rh/P[(CH2)7CH3]3 catalyst. The fluorous biphase catalyst recovery concept was tested in a semicontinuous hydroformylation of decene-1 with the Rh/P[CH2CH2(CF2)5CF3]3 catalyst. During 9 consecutive reaction/separation cycles, a total turnover of more than 35 000 was achieved with a loss of 1.18 ppm of Rh/mol of undecanals. The fluorous-soluble Rh/P[CH2CH2(CF2)5CF3]3 catalyst was also tested for the continuous hydroformylation of ethylene using the high-boiling fluorous solvent FC-70, which allows continuous removal of propanal at the reaction temperature of 110 °C. The long-term stability of the Rh/P[CH2CH2(CF2)5CF3]3 catalyst is better than that of the Rh/PPh3 catalyst. Thus, the Rh/P[CH2CH2(CF2)5CF3]3 catalyst is the first catalyst system which can be used for the hydroformylation of both low and high molecular weight olefins and provides facile catalyst separation for both low and high molecular weight aldehydes.
- Horváth, István T.,Kiss, Gábor,Cook, Raymond A.,Bond, Jeffrey E.,Stevens, Paul A.,Rábai, József,Mozeleski, Edmund J.
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p. 3133 - 3143
(2007/10/03)
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- Nickel mediated conversion of acyl halides in aldehydes
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Aldehydes are obtained from acyl halides employing stoichiometric tri n.butyl tin hydride (TBTH) and catalytic nickeldiphenylphosphinoethane dichloride (NidppeCl2), at room temperature.
- Malanga, Corrado,Mannucci, Serena,Lardicci, Luciano
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p. 8093 - 8096
(2007/10/03)
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- Organometallic chemistry sans organometallic reagents: Modulated electron-transfer reactions of sub valent early transition metal salts
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The potential of low-valent, early transition-metal reagents as selective reductants in organic chemistry has been foreshadowed by intensive research on the ill-defined and heterogeneous subvalent titanium intermediates generated in the McMurry reaction and its numerous variants. As part of a long-term research effort to develop soluble, well-defined transition-metal reductants of modulated and selective activity toward organic substrates, the THF-soluble reductant, titanium dichloride, has been thoroughly examined, as well as the analogous ZrCl2 and HfCl2 reagents, all of which are readily obtainable by the alkylative reduction of the Group 4 tetrachloride by butyllithium in THF. Noteworthy is that such interactions of MCl4, with butyllithium in hydrocarbon media lead, in contrast, to M(III) or M(IV) halide hydrides. Analogous alkylative reductions in THF applied to VCl4, CrCl3, and MoCl5 have yielded reducing agents similar to those obtained from MCl4 but gradated in their reactivity. Such reductants have proved capable of coupling carbonyl derivatives, benzylic halides, acetylenes and certain olefins in a manner consistent with an oxidative addition involving a two-electron transfer (TET). Such a reaction pathway is consistent with the observed stereochemistry for pinacol formation from ketones and for the reductive dimerization of alkynes. In contrast to the reaction of CrCl3 with two equivalents of butyllithium, which leads to a CrCl intermediate, the interaction of CrCl3 in THF with four equivalents of butyllithium at -78°C yields a reagent of the empirical formulation, LiCrH4 · 2 LiCl · 2 THF, as supported by elemental and gasometric analysis of its protolysis. This hydridic reductant cleaves a wide gamut of o carbon-heteroatom bonds (C-X, C-O, C-S and C-N), towards which the CrCl reductant is unreactive. The type of cleavage and/or coupled products resulting from the action of "LiCrH4" on these substrates is best understood as arising from single-electron transfer (SET). In light of the aforementioned findings, the gradated reducing action noted among TiCl2, ZrCl2, HfCl2 and CrCl, as well as the contrasting reducing behavior between CrCl and LiCrH4, there is no doubt that future research with early transition metals will continue to yield novel reductants of modulated and site-selective reactivity. VCH Verlagsgesellschaft mbH,.
- Eisch, John J.,Shi, Xian,Alila, Joseph R.,Thiele, Sven
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p. 1175 - 1187
(2007/10/03)
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- Isomerization of allyltrisubstituted silanes and decenes accompanying their cometathesis in the presence of ruthenium complexes
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It was found that the product of cometathesis of allyltrisubstituted silanes and 1-decene in the presence of different complexes of ruthenium was (E)-and (Z)-R3SiCH=CHR1 (R = Me or EtO; R1 = n-C8H17.). The cometathesis was accompanied by the migration of a double bond in allylsilanes and 1-decene. The isomerization of allyltrisubstituted silanes to appropriate propenyltrisubstituted silanes as well as of 1-, 2-, and 4 - alkenes to isomeric alkenes in the presence of ruthenium complexes was investigated too. It was proved that the migration of a double bond is accompanied by (E) - (Z) isomerization. Products of the first stage of the migration reaction are mainly (E) isomers. Isomerization proceeds at lower temperatures than cometathesis. Tetrachloroethylene as a solvent was favorable for isomerization, but it inhibited cometathesis.
- Foltynowicz,Krompiec,Wagner,Maciejewski
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p. 468 - 475
(2007/10/03)
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- Isomerization of 1-alkenes using the Na2Fe(CO)4/CuCl and Na2Fe(CO)4/BrCH2CH2Br reagent systems
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The reagent Na2Fe(CO)4 prepared in situ in THF by the reduction of Fe(CO)5 with sodium naphthalenide reacts with certain alkenes in the presence of CuCl to bring about isomerization of the alkenes.Thus the 1-alkenes (1-dodecene, 1-decene, safrole and allyl benzene) are isomerized to trans-2-alkenes, and β-pinene is isomerized to α-pinene.Reactions involving BrCH2CH2Br in place of CuCl give similar results.Keywords: Isomerization; Supernucleophile; Iron tetracarbonyl; Iron-copper bonds; Iron pentacarbonyl; Copper(I) chloride
- Reddy, Malladi Rama,Periasamy, Mariappan
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p. 263 - 266
(2007/10/02)
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- Allylbarium reagents: Unprecedented regio- and stereoselective allylation reactions of carbonyl compounds
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The first direct preparation of allylbarium reagents by reaction of in situ generated reactive barium with various allylic chlorides and their new and unexpected selective allylation reactions with carbonyl compounds are disclosed. Highly reactive barium was readily prepared by the reduction of barium iodide with 2 equiv of lithium biphenylide in dry THF at room temperature. A variety of carbonyl compounds reacted with barium reagents generated from (E)- or (Z)-allylic chlorides in THF at -78 °C. All reactions resulted in high yields with remarkable α-selectivities not only with aldehydes but also with ketones. The double bond geometry of the starting allylic chloride was completely retained in each case. Stereochemically homogeneous (E)- and (Z)-β,γ-unsaturated carboxylic acids were easily prepared in good yields by highly α-selective carboxylation of allylic barium reagents with carbon dioxide. A selective Michael addition reaction with α,β-unsaturated cycloalkanone was also achieved using an allylbarium reagent. Treatment of 2-cyclopentenone (1 equiv) with allylbarium chloride (2 equiv) in THF at -78 °C for 20 min afforded 3-allylcyclopentanone in 94% yield with a 1,4/1,2 ratio of >99/1. Furthermore, the in situ generated barium enolate was efficiently trapped with various kinds of electrophiles (Me2C=CHCH2Br, nC5H11CHO, and CH3COCl).
- Yanagisawa, Akira,Habaue, Shigeki,Yasue, Katsutaka,Yamamoto, Hisashi
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p. 6130 - 6141
(2007/10/02)
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- Hindered organoboron groups in organic chemistry. 25. The condensation of aliphatic aldehydes with dimesitylboryl stabilised carbanions to give alkenes
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In the presence of protic acids the condensation of aliphatic aldehydes with dimesitylboryl stabilised carbanions results in alkenes. In the presence of strong acids such as HCl or CF3SO3H, the products contain > 90% of E-alkenes in all cases tried. When acetic acid is used, the Z-alkenes may result predominantly, particularly in the cases of R(S)CHO and R(t)CHO.
- Pelter,Smith,Elgendy
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p. 7119 - 7132
(2007/10/02)
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- Telluroxide Elimination by Oxidation of Alkyl Aryl Tellurides: Remarkable Effect of Added Triethylamine
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Treatment of various alkyl phenyl tellurides with 1-2 mol equiv. of m-chloroperbenzoic acid in diethyl ether in the presence of triethylamine at 25 deg C for 2 h affords the corresponding alkenes highly selectively in fair to good yields.From stereochemical studies using erythro- and threo-phenyl 3-phenylbutan-2-yl tellurides as substrates it was revealed that although Et3N partly faciliates E2 elimination of the telluroxide, the main reaction course is the telluroxide syn-elimination (Ei elimination).Without the addition of Et3N the elimination was quite slow in many cases, and in fact the compounds derived from the addition of m-chlorobenzoic acid to tetradecyl and cyclohexyl phenyl telluroxides were isolated, the pyrolysis (ca. 250 deg C) of which afforded tetradec-1-ene and cyclohexene, respectively.A 2-pyridyltelluro moiety was revealed for the first time to be a better leaving group than a phenyltelluro moiety in telluroxide elimination.
- Nishibayashi, Yoshiaki,Komatsu, Naoki,Ohe, Kouichi,Uemura, Sakae
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p. 1133 - 1138
(2007/10/02)
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- Metal/Ammonia Reduction of Ethers of 3-Decyn-1-ol: Effects of Structure and Conditions on Cleavage and Rearrangement
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Reduction of the THP, ethyl, tert-butyl and tert-butyldimethylsilyl (TBDMS) ethers of 3-decyn-1-ol with sodium in ammonia/THF results in extensive hydrogenolysis of the carbon-oxygen bond and concomitant bond migration, producing a mixture of 2- and 3-decenes and a very low yield of the desired (E)-homoallylic ether.Reduction in the presence of 2-methyl-2-propanol led to excellent yields of the desired (E)-3-decenol ethers.The 4- and 5-decyn-1-ol ethers were reduced normally to the (E)-decen-1-ol ethers except in the case of the TBDMS ethers which were cleaved to the (E)-alcohols under some of the reaction conditions.
- Doolittle, Robert E.,Patrick, Delrea G.,Heath, Robert H.
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p. 5063 - 5066
(2007/10/02)
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- A new olefin synthesis based on the radical induced elimination of a nitro group
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Nitroalkanes can be transformed into olefins in high yielding reactions via nitroolefins and β-nitro trithiocarbonates in radical olefination reactions.
- Barton, Derek H. R.,Dorchak, Joseph,Jaszberenyi, Joseph Cs.
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p. 8051 - 8054
(2007/10/02)
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- REGIOSELECTIVE REPLACEMENT OF THE HYDROXY GROUP IN ALCOHOLS BY MEANS OF TRIHALOACETIC DERIVATIVES IN PRESENCE OF TRIPHENYLPHOSPHINE
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The investigation of the reactions of trichloroacetonitrile with 2-decanol, 2-methyl-3-octanol, 2,4-dimethyl-3-pentanol, and 2,2-dimethyl-1-propanol in presence of triphenylphosphine shows that the formation of alkyl chlorides from the corresponding alcohols goes regiospecifically: Even for 2,4-dimethyl-3-pentanol the amount of the isomeric chloride does not exceed 1percent, while neopentyl alcohol is converted into neopentyl chloride in 95percent yield.On the introduction of "external" nucleophiles (iodide and thiocyanate ions) into the reaction mixture the predominating reaction product is the alkyl chloride.As a result of the reaction of bromotrichloromethane with 1-nonanol and triphenylphosphine a mixture of the alkyl chloride and the alkyl bromide is formed.
- Matveeva, E. D.,Yalovskaya, A. I.,Cherepanov, I. A.,Bundel', Yu. G.,Kurts, A. L.
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p. 1409 - 1415
(2007/10/02)
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- PREFERENTIAL cis-OLEFIN FORMATION: A STRIKING RESEMBLANCE BETWEEN ALKALI-ALKOXIDE AND ALUMINA PROMOTED ELIMINATIONS IN LOW POLAR SOLVENTS
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Olefin-isomer distribution has been investigated in the Woelm alumina promoted elimination from a series of 2-decyl and 5-decyl derivatives (X= F, Cl, Br, I, OTs) in ether.From the observed effect of leaving group it has been inferred that the heterogeneous reaction is a concerted process.A comparison has been made with corresponding results from homogeneous, alkali-alkoxide promoted eliminations in low polar solvents.A striking similarity in steric course between the two reactions has been noted and explained in terms of acid-base co-catalysis.
- Zavada, Jiri,Pankova, Magdalena
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p. 704 - 709
(2007/10/02)
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- ON THE ORIGIN OF BASE CONCENTRATION EFFECT ON STEREO AND REGIOSELECTIVITY IN ALKOXIDE-PROMOTED E2 REACTIONS: A CONSEQUENCE OF SUBSTRATE SOLVATION BY METAL IONS
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The title problem has been investigated in the reaction of 2-decyl bromide with t-C4H9OK/t-C4H9OH system employing 18-crown-6 ether and an "inert" salt (t-C4H9OLi) as mechanistic probes.From olefin-distribution data and a subsidiary kinetic evidence it has been inferred that the investigated effect originates from a concentration-dependent substrate solvation by metal ions in the transition state.
- Zavada, Jiri,Pankova, Magdalena,Vitek, Antonin
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p. 695 - 703
(2007/10/02)
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