- Effect of the nature of carbene fragments in the tungsten complexes PhMe2E-CH=W(NAr)(OR')2 and Me3E-CH=W(NAr)(OR') 2 (E = C, Si) on their catalytic properties in olefin metathesis reactions
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Catalytic properties of the silicon-containing carbene complexes of tungsten Me3Si-CH=W(NAr)(OR')2(1) and PhMe 2Si-CH=W(NAr)(OR')2 (2) and their hydrocarbon analogs Me3C-CH=W(NAr)(OR')2 (3) and PhMe2C-CH=W(NAr) (OR')2 (4) (Ar = 2,6-Pri 2C6H 3, R' = CMe2CF3) were studied in homometathesis of hex-1-ene, metathesis polycondensation of deca-1,9-diene, and ring opening metathesis polymerization of cyclooctene. The nature of the carbene fragment in the tungsten catalysts substantially affects their catalytic activity. Silicon-containing catalysts 1 and 2 were found to be 3-5 times less active than their hydrocarbon analogs 3 and 4. Metathesis polymerization of cyclooctene in the bulk with initiators 1-4 completed within a few minutes to form a block. Stereoregularity of the formed polyoctenamers depends to a considerable extent on the nature of the carbene fragments in the starting initiators. Initiators 1-2 lead to polyoctenamers mainly containing the cis-units, whereas the use of complexes 3 and 4 affords polyoctenamers mainly containing the trans-units. The structures of novel compound 2 and known complexes 1, 3, and 4 were determined by X-ray diffraction analysis.
- Bochkarev,Begantsova,Platonova,Basova,Grigor'eva,Stolyarova,Malysheva,Fukin,Baranov,Kurskii,Bochkarev,Abakumov
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Read Online
- SYNTHESIS OF PHEROMONE DERIVATIVES VIA Z-SELECTIVE OLEFIN METATHESIS
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Disclosed herein are methods for synthesizing fatty olefin metathesis products of high Z-isomeric purity from olefin feedstocks of low Z-isomeric purity. The methods include contacting a contacting an olefin metathesis reaction partner, such as acylated alkenol or an alkenal acetal, with an internal olefin in the presence of a Z-selective metathesis catalyst to form the fatty olefin metathesis product. In various embodiments, the fatty olefin metathesis products are insect pheromones. Pheromone compositions and methods of using them are also described.
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Paragraph 0222; 0226-0229
(2021/12/28)
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- Enantiopure 2,9-Dideuterodecane – Preparation and Proof of Enantiopurity
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(R,R)- and (S,S)-(2,9-2H2)-n-Decane were prepared regio- and stereospecifically in 25–26 % yield over five steps from commercially available enantiopure (R)- and (S)-propylene oxide, respectively. The synthetic procedure involved nucleophilic displacement of (R)- and (S)-4-toluenesulfonic acid 1-methyl-4-pentenyl ester with LiAlD4 to furnish the respective (5-2H)-1-hexenes. Subsequent olefin metathesis and reduction of the double bond furnished the title compounds. The optical purity of (R,R)- and (S,S)-(2,9-2H2)-n-decane could not be determined by chromatography or polarimetry. Therefore, (R,R)- and (R,S)-(5-2H)-3-hydroxy-2-hexanone were prepared from their respective hexenes by Wacker oxidation, followed by enantioselective α-hydroxylation. The enantiopurity could then be determined by NMR spectroscopy because the stereospecifically deuterated hydroxyketones showed separated signals for the subterminal carbon atom (C-5) in the 13C NMR spectrum.
- Christoffers, Jens,Eru?ar, Gülsera,Fsadni, Miriam H.,Golding, Bernard T.,Mitschke, Nico,Roberts, Amy R.,Sadeghi, Majid M.,Wilkes, Heinz
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p. 3854 - 3863
(2021/08/24)
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- Cationic Tungsten Imido Alkylidene N-Heterocyclic Carbene Complexes That Contain Bulky Ligands
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Neutral and cationic tungsten imido alkylidene complexes of the general formulas W(NtBu)(CHR1)(OR2)Cl(NHC), W(N-2,6-bis(2,4,6-tri-iPr-C6H4)phenyl)(CHR1)Cl2(NHC), [W(NtBu)(CHR1)(OR2)(NHC)][B(ArF)4] and [W(N-2,6-bis(2,4,6-tri-iPr-C6H4)phenyl)(CHR1)Cl(NHC)][B(ArF)4] (R1= CMe3, CMe2Ph; R2= sterically demanding alkoxide; B(ArF)4= tetrakis(3,5-(CF3)2-C6H3)borate; NHC = N-heterocyclic carbene) were prepared. Two electronically different NHCs, namely 1,3-dimethylimidazol-2-ylidene (IMe) and 1,3-dimethyl-4,5-dichloroimidazol-2-ylidene (IMeCl), as well as a variety of terphenolates and a chiral biphenolate were employed.Z-selective homometathesis (HM) of unfunctionalized olefins was achieved with a selectivity of up to 90% and decent turnover numbers (TON) of up to 480 in the HM of 1-dodecene. Additionally, the reactivity of the cationic tungstentert-butylimido complexes in the reaction with vinyltrimethylsilane and ethylene was investigated, which yielded the corresponding silyl-alkylidene complex and, for the first time, a fully characterized cationic tungsten(IV) NHC ethylene complex.
- Buchmeiser, Michael R.,Frey, Wolfgang,Musso, Janis V.,Schowner, Roman
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p. 3145 - 3157
(2021/09/30)
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- Dinuclear cobalt complex-catalyzed stereodivergent semireduction of alkynes: Switchable selectivities controlled by H2O
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Catalytic semireduction of internal alkynes to alkenes is very important for organic synthesis. Although great success has been achieved in this area, switchable Z/E stereoselectivity based on a single catalyst for the semireduction of internal alkynes is a longstanding challenge due to the multichemo- and stereoselectivity, especially based on less-expensive earth-abundant metals. Herein, we describe a switchable semireduction of alkynes to (Z)- or (E)-alkenes catalyzed by a dinuclear cobalt complex supported by a macrocyclic bis pyridyl diimine (PDI) ligand. It was found that cis-reduction of the alkyne occurs first and the Z-E alkene stereoisomerization process is formally controlled by the amount of H2O, since the concentration of H2O may influence the catalytic activity of the catalyst for isomerization. Therefore, this protocol provides a facile way to switch to either the (Z)- or (E)-olefin isomer in a single transformation by adjusting the amount of water.
- Chen, Ke,Zhu, Hongdan,Li, Yuling,Peng, Qian,Guo, Yinlong,Wang, Xiaoming
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p. 13696 - 13705
(2021/11/16)
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- An Annelated Mesoionic Carbene (MIC) Based Ru(II) Catalyst for Chemo- And Stereoselective Semihydrogenation of Internal and Terminal Alkynes
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The catalytic utility of [RuL1(CO)2I2] (1), containing an annelated π-conjugated imidazo-naphthyridine-based mesoionic carbene (MIC) ligand (L1), is evaluated for E-selective alkyne semihydrogenation. The precatalyst 1, in combination with 2 equiv of AgBArF, semihydrogenates a broad range of internal alkynes with molecular hydrogen (5 bar) in water. (E)-Alkenes are accessed in high yields, and a number of reducible functional groups are tolerated. A chelate MIC ligand and two cis carbonyls provide a well-defined platform at the Ru center for hydrogenation and isomerization. The loss of two iodides and the presence of two carbonyls render the Ru center electron deficient and thus the formation of metal vinylidenes with terminal alkynes is avoided. This is leveraged for the semihydrogenation of terminal alkynes by the same catalytic system in isopropyl alcohol. Reaction profile, isomerization, kinetic, and DFT studies reveal initial alkyne hydrogenation to a (Z)-alkene, which further isomerizes to an (E)-alkene via metal-catalyzed Z → E isomerization.
- Bera, Jitendra K.,Choudhury, Joyanta,Das, Shubhajit,Dutta, Indranil,Pati, Swapan K.,Saha, Sayantani,Yadav, Suman
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p. 3212 - 3223
(2020/10/02)
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- Silica-supported Z-selective Ru olefin metathesis catalysts
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Recently reported thiolate-coordinated ruthenium alkylidene complexes show promise in Z-selective and stereoretentive olefin metathesis reactions. Herein we describe the immobilization of three Ru complexes containing a bulky aryl thiolate on mesostructured silica via surface organometallic chemistry. The applied methodology gives isolated catalytic sites homogeneously distributed on the silica surface. The catalytic results with two model substrates show comparable Z-selectivities to those of the homogeneous counterparts.
- Renom-Carrasco, Marc,Mania, Philipp,Sayah, Reine,Veyre, Laurent,Occhipinti, Giovanni,Jensen, Vidar R.,Thieuleux, Chloé
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- Molybdenum Benzylidyne Complexes for Olefin Metathesis Reactions
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The molybdenum benzylidynes [ArCMo(OC(CF3)2CH3)3(1,2-dimethoxyethane)], where Ar = Ph (2a), p-(OCH3)C6H4 (2b), p-(CF3)C6H4 (2c), p-(NO2)C6H4 (2d), or 4-(NO2)-3-(CF3)C6H3 (2e), and [p-(NO2)C6H4CMo(OC(CF3)2CH3)3] (2f) catalyze the ring-closing metathesis (RCM) reaction of diallyl N-tosylamide (3) to produce 1-tosyl-2,5-dihydro-1H-pyrrole (4) and ethylene. The scope of RCM catalytic activity of 2e, cross-metathesis of 1-hexene, and ring-opening metathesis polymerization of cyclooctene were explored. The X-ray crystal structure of 2e was determined. Variable-temperature 1H NMR spectra revealed the formation of intermediates during the reaction of 3 with 2f and the reforming of 2f after completion of the reaction. The use of 13C-labeled Mo benzylidyne did not show transfer of the carbon atom next to Mo to any of the products.
- Acosta, Carlos M.,Bukhryakov, Konstantin V.,Chuprun, Sergey,Mathivathanan, Logesh
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supporting information
p. 3453 - 3457
(2020/11/02)
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- Activation of Low-Valent, Multiply M-M Bonded Group VI Dimers toward Catalytic Olefin Metathesis via Surface Organometallic Chemistry
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Olefin metathesis is a broadly employed reaction with applications that range from fine chemicals to materials and petrochemicals. The design and investigation of olefin metathesis catalysts have been ongoing for over half a century, with advancements made in terms of activity, stability, and selectivity. Immobilization of organometallic complexes onto solid supports such as silica or alumina is a promising strategy for catalyst heterogenization, often resulting in increased activity and stability. Consequently, a broad range of early transition metal catalysts bearing alkyl, oxide/alkoxide, and amide ligands have been grafted onto silica and their reactivities investigated. Herein, we report a series of silica-supported tungsten and molybdenum dimers (X3MMX3, where M = W and Mo; X = neopentyl, tert-butoxide, and dimethyl amide) and their reactivities toward catalytic olefin metathesis. Dynamic nuclear polarization (DNP)-enhanced solid-state nuclear magnetic resonance (SSNMR), diffuse reflectance infrared Fourier transform (DRIFT), UV resonance Raman, and X-ray absorption (XAS) spectroscopies suggest that upon heterogenization the dimers bind to the surface in a monopodal fashion, with the MM triple bond remaining intact. These structural assignments were further corroborated by density functional theory (DFT) calculations. While the homogeneous dimer counterparts are inert, the supported low-valent alkyl W and Mo dimers become active for the disproportionative self-metathesis of propylene to ethylene and butenes and 4-nonene to 4-octene and 5-decene under mild conditions. The lack of activity observed for the free and supported tert-butoxide and dimethyl amide dimers likely suggests that the neopentyl groups are necessary for the formation of a putative alkylidene active species. The difference in reactivity between the free and supported dimers could be explained either by the lowering of the activation barrier of the complex through the electronic effects of the surface or by site isolation of catalytically relevant reactive intermediates.
- Celik, Gokhan,Chapovetsky, Alon,Delferro, Massimiliano,Dogan, Fulya,Ferrandon, Magali S.,Kaphan, David M.,Khetrapal, Navneet,Kim, Hacksung,Kropf, A. Jeremy,Langeslay, Ryan R.,Perras, Frédéric A.,Pruski, Marek,Sattelberger, Alfred P.,Sharma, Prachi,Wegener, Evan C.,Wen, Jianguo,White, Jacob
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supporting information
p. 1035 - 1045
(2020/05/04)
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- Method for selective synthesis of cis-olefins and trans-olefins by semi-reduction of alcohol hydrogen supply palladium-catalyzed alkynes
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The invention provides a method for selective synthesis of cis-olefins and trans-olefins by semi-reduction of alcohol hydrogen supply palladium-catalyzed alkynes. The method comprises the following steps: performing alkyne reduction reaction with TEOA, NaOAc, a catalyst, alcohol and alkynes in an organic solvent and generating the cis-olefins after reaction; performing alkyne reduction reaction with a ligand, a catalyst, alcohol and alkynes in an organic solvent and generating the trans-olefins after reaction; a reactor for the reduction reaction is a sealed pressure-resistant reactor, the reduction reaction temperature is 120-150 DEG C, and the reduction reaction time is 20-48 hours; the dosage of the catalyst is 5-20 percent of the molar dosage of the alkynes, and the dosage of the alcohol is 10-100 times of the molar dosage of the alkynes; the dosage of R, R-DIPAMP is 0.5-5 times of the molar dosage of the alkynes. According to the method provided by the invention, a catalyst systemhas extremely-high chemical reaction and stereo-selectivity and can synthesize cis-olefin products or trans-olefin products with high yield; the catalyst system is good universality to a substrate, and the alkynes containing various functional groups can be efficiently subjected to the highly-selective reduction reactions.
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Paragraph 0174-0176
(2019/06/07)
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- Ligand-controlled iridium-catalyzed semihydrogenation of alkynes with ethanol: highly stereoselective synthesis of E- and Z-alkenes
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A ligand-controlled iridium-catalyzed semihydrogenation of alkynes to E- and Z-alkenes with ethanol was developed. Effective selectivity control was achieved by ligand regulation. The use of 1,2-bis(diphenylphosphino)ethane (DPPE) and 1,5-cyclooctadiene (COD) was critical for the stereoselective semihydrogenation of alkynes. The general applicability of this procedure was highlighted by the synthesis of more than 40 alkenes, with good stereoselectivities. The value of our approach in practical applications was investigated by studying the effects of pinosylvin and 4,4′-dihydroxystilbene (DHS) on zebrafish as a vertebrate model.
- Yang., Jinfei,Wang, Chengniu,Sun, Yufeng,Man, Xuyan,Li, Jinxia,Sun, Fei
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supporting information
p. 1903 - 1906
(2019/05/02)
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- Supported Ru olefin metathesis catalysts: Via a thiolate tether
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Thiolate-coordinated ruthenium alkylidene complexes can give high Z-selectivity and stereoretentivity in olefin metathesis. To investigate their applicability as heterogeneous catalysts, we have successfully developed a methodology to easily immobilize prototype ruthenium alkylidenes onto hybrid mesostructured silica via a thiolate tether. In contrast, the preparation of the corresponding molecular complexes appeared very challenging in solution. These prototype supported complexes contain small thiolates but still, they are slightly more Z-selective than their molecular analogues. These results open the door to more active and selective heterogeneous catalysts by supporting more advanced thiolate Ru-complexes.
- Renom-Carrasco, Marc,Mania, Philipp,Sayah, Reine,Veyre, Laurent,Occhipinti, Giovanni,Gajan, David,Lesage, Anne,Jensen, Vidar R.,Thieuleux, Chloé
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supporting information
p. 2886 - 2890
(2019/03/07)
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- Normal Alpha Olefin Synthesis Using Dehydroformylation or Dehydroxymethylation
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The present invention discloses processes for producing normal alpha olefins, such as 1-hexene, 1-octene, 1-decene, and 1-dodecene in a multistep synthesis scheme from another normal alpha olefin. Also disclosed are reactions for converting aldehydes, primary alcohols, and terminal vicinal diols into normal alpha olefins.
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Paragraph 0146-0148
(2019/09/06)
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- Vanadium-Catalyzed Cross Metathesis: Limitations and Implications for Future Catalyst Design
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Self-metathesis of terminal olefins using vanadium(V) alkylidenes is presented. Under various reaction conditions, incomplete conversion is observed due to decomposition of the metallocyclobutane intermediate via β-hydride elimination. The activity was observed to decline when a more electron withdrawing, less sterically bulky ligand was used, in contrast to trends observed in ring-opening metathesis polymerization with vanadium catalysts. These results provide insight into the current limitations of olefin metathesis with vanadium catalysts, as well as guidance for catalyst development.
- Farrell, Wesley S.
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supporting information
p. 3481 - 3485
(2019/11/13)
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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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Paragraph 0099; 0100; 0101
(2018/05/24)
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- SOMC-designed silica supported tungsten Oxo imidazolin-2-iminato methyl precatalyst for olefin metathesis reactions
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Synthesis, structure, and olefin metathesis activity of a surface complex [(Si-O-)W(=O)(CH3)2- ImDippN] (4) (ImDipp = 1,3-bis(2,6-diisopropylphenyl)- imidazolin-2-iminato) supported on silica by a surface organometallic chemistry (SOMC) approach are reported. The reaction of N-silylated 2-iminoimidazoline with tungsten- (VI) oxytetrachloride generated the tungsten oxo imidazolin-2- iminato chloride complex [ImDippNW(O)Cl3] (2). This was grafted on partially dehydroxylated silica pretreated at 700 °C (SiO2-700) to afford a well-defined monopodal surface complex [(Si-O-)W(=O)Cl2-ImDippN] (3). 3 underwent alkylation by ZnMe2 to produce [(Si-O-)W(=O)(CH3)2-ImDippN] (4). The alkylated surface complex was thoroughly characterized by solid-state NMR, elemental microanalysis, Raman, FT-IR spectroscopies, and XAS analysis. 4 proved to be an active precatalyst for self-metathesis of terminal olefins such as propylene and 1-hexene.
- Qureshi, Ziyauddin S.,Hamieh, Ali,Barman, Samir,Maity, Niladri,Samantaray, Manoja K.,Ould-Chikh, Samy,Abou-Hamad, Edy,Falivene, Laura,D'Elia, Valerio,Rothenberger, Alexander,Llorens, Isabelle,Hazemann, Jean-Louis,Basset, Jean-Marie
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supporting information
p. 861 - 871
(2017/01/24)
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- N-Heterocyclic Carbene Complexes Of Metal Imido Alkylidenes And Metal OXO Alkylidenes, And The Use Of Same
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The invention relates to an N-heterocyclic carbene complex of general formulas I to IV (I) (II) (III) (IV), according to which A1 stands for NR2 or PR2, A2 stands for CR2 R2′, NR2, PR2, 0 or S, A3 stands for N or P, and C stands for a carbene carbon atom, ring B is an unsubstituted or a mono or poly-substituted 5 to 7-membered ring, substituents R2 and R2′ stand, inter alia, for a linear or branched C1-Cw-alkyl group and, if N and N each stand for NR2 or PR2, are the same or different, M in formulas I, II, III or IV stands for Cr, Mo or W, X 1 or X2 in formulas I to IV are the same or different and represent, inter alia, C1-C1s carboxylates and C1-C1s-alkoxides, Y is inter alia oxygen or sulphur, Z is inter alia a linear or branched C1-Cw-alkylenoxy group, and R 1 and R1′ in formulas I to IV are, inter alia, an aliphatic or aromatic group. These compounds are particularly suitable for use as catalysts for olefin metathesis reactions and have the advantage, compared to known Schrock carbene complexes, of displaying clearly increased tolerance to functional groups such as, in particular, aldehydes, secondary amines, nitriles, carboxylic acids and alcohols.
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Paragraph 0181
(2017/03/21)
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- PROCESS FOR PREPARING MONO AND DICARBOXYLIC ACIDS
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The present application relates to a process for preparing a dicarboxylic acid or dicarboxylic ester according to general formula (IV) R1OOC-(CH2)m-CH2CH2-(CH2)y-COOR4 (IV), comprising the steps of subjecting alkenoic acid or alkenoate of formula (II) R1OOC-(CH2)m-CH=CH-(CH2)x-H (II) to a metathesis reaction in the presence of a metathesis catalyst to form a longer-chain alkenoic acid or alkenoate of formula (III) R1OOC-(CH2)m-CH=CH-(CH2)y-H (III) where xa carbonylation reaction in the presence of a carbonylation catalyst and a carbonyl source to form said compound of Formula (IV). Alternative embodiments provide: a process for preparing an alkenoic acid or alkenoate comprising the step of subjecting a lactone to a ring opening reaction; a process for preparing a monocarboxylic acid or monocarboxylic ester according to general formula (XI) R1OOC-(CH2)m-CH2-(CH2)y-CH3 (XI) by subjecting an alkenoic acid or alkenoate to alkene hydrogenation; and a process for preparing an alcohol or ether according to general formula (XII) R1O-CH2-(CH2)m-CH2-(CH2)y-CH3 (XII) by subjecting an alkenoic acid or alkenoate to hydrogenation. The use of the respective mono/dicarboxylic acid, mono/dicarboxylic ester, ethers or alcohols in a variety of applications is also disclosed.
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Page/Page column 26; 35; 36
(2018/02/03)
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- OLEFIN METATHESIS CATALYSTS
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This invention relates generally to metathesis catalysts and the use of such catalysts in the metathesis of olefins and olefin compounds, more particularly, in the use of such catalysts in Z and E selective olefin metathesis reactions. The invention has utility in the fields of organometallics and organic synthesis.
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Page/Page column 87
(2017/07/06)
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- High Trans Kinetic Selectivity in Ruthenium-Based Olefin Cross-Metathesis through Stereoretention
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The first kinetically controlled, highly trans-selective (>98%) olefin cross-metathesis reaction is demonstrated using Ru-based catalysts. Reactions with either trans or cis olefins afford products with highly trans or cis stereochemistry, respectively. This E-selective olefin cross-metathesis is shown to occur between two trans olefins and between a trans olefin and a terminal olefin. Additionally, new stereoretentive catalysts have been synthesized for improved reactivity. (Chemical Equation Presented).
- Johns, Adam M.,Ahmed, Tonia S.,Jackson, Bradford W.,Grubbs, Robert H.,Pederson, Richard L.
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supporting information
p. 772 - 775
(2016/03/01)
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- Molybdenum and Tungsten Alkylidene Complexes That Contain a 2-Pyridyl-Substituted Phenoxide Ligand
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In the interest of preparing molybdenum and tungsten alkylidene complexes for olefin metathesis that are longer-lived at high temperatures (~150 °C or above), we synthesized complexes that contain a phenoxide ligand with a 2-pyridyl in one ortho position and a mesityl (Mes) or 2,4,6-i-Pr3C6H2 (Trip) in the other ortho position ([MesON]- or [TripON]-, respectively). The alkylidene (neophylidene) complexes that were prepared include W(O)(CHCMe2Ph)(Me2Pyr)(RON) (R = Mes or Trip), Mo(NC6F5)(CHCMe2Ph)(RON)Cl, Mo(N-2,6-Me2C6H3)(CHCMe2Ph)(RON)Cl, Mo(N-t-Bu)(CHCMe2Ph)(RON)Cl, and M(N-2,6-i-Pr2C6H3)(CHCMe2Ph)(TripON)(OTf) (M = Mo or W). The reaction between Mo(NAr)(CHCMe2Ph)(TripON)(OTf) and ethylene yielded an ethylene complex, Mo(NAr)(C2H4)(TripON)(OTf)(ether). All neophylidene complexes were essentially unreactive toward terminal olefins at 22 °C and showed modest homocoupling activity (at 80 or 100 °C) and alkane metathesis activity (at 150 and 200 °C). W(O)(CHCMe2Ph)(Me2Pyr)(MesON) also stereoselectively polymerized several substituted norbornadienes at 100 °C.
- Sues, Peter E.,John, Jeremy M.,Bukhryakov, Konstantin V.,Schrock, Richard R.,Müller, Peter
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supporting information
p. 3587 - 3593
(2016/11/06)
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- Alkyne Semihydrogenation with a Well-Defined Nonclassical Co-H2 Catalyst: A H2 Spin on Isomerization and E-Selectivity
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The reactivity of a CoI-H2 complex was extended toward the semihydrogenation of internal alkynes. Under ambient temperatures and moderate pressures of H2, a broad scope of alkynes were semihydrogenated using a CoI-N2 precatalyst, resulting in the formation of trans-alkene products. Furthermore, mechanistic studies using 1H, 2H, and para-hydrogen induced polarization (PHIP) transfer NMR spectroscopy revealed cis-hydrogenation of the alkyne occurs first. The Co-mediated alkene isomerization afforded the E-selective products from a broad group of alkynes with good yields and E/Z selectivity.
- Tokmic, Kenan,Fout, Alison R.
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supporting information
p. 13700 - 13705
(2016/10/31)
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- Highly Z-selective olefins metathesis
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The present invention relates generally to catalysts and processes for the Z-selective formation of internal olefin(s) from terminal olefin(s) via homo-metathesis reactions.
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Page/Page column 35; 44
(2015/07/22)
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- SYNTHESIS OF OLEFINIC ALCOHOLS VIA ENZYMATIC TERMINAL HYDROXYLATION
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In certain aspects, the present invention provides methods for producing terminally hydroxylated alkenes and alkynes by contacting an unsaturated or saturated hydrocarbon substrate with a hydroxylase enzyme. Exemplary terminal hydroxylases useful for carrying out the methods of the invention exhibit strong selectivity towards one terminal carbon of a hydrocarbon substrate and include, but are not limited to, non-heme diiron alkane monooxygenases, cytochromes P450 (e.g., cytochromes P450 of the CYP52 and CYP153 family), as well as long chain alkane hydroxylases. In some embodiments, the terminally hydroxylated alkene or alkyne is further converted to a terminal alkenal. In certain embodiments, terminally hydroxylated alkenes and alkynes are useful as insect pheromones which modify insect behavior. In other embodiments, terminally hydroxylated alkenes and alkynes are useful intermediates for producing pheromones via acetylation or oxidation of the alcohol moiety.
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Paragraph 0273; 0274
(2016/01/30)
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- Olefin metathesis catalysts
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The present invention refers to novel ruthenium- and osmium-based catalysts for olefin metathesis reactions, particularly to catalysts having stereoselective properties. Z-selectivity is obtained by utilizing two mono-anionic ligands of very different steric requirement. In olefin metathesis reactions these catalysts selectively provide the Z-isomer of disubstituted olefinic products.
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Page/Page column 26; 27
(2014/05/20)
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- Theory-assisted development of a robust and Z-selective olefin metathesis catalyst
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DFT calculations have predicted a new, highly Z-selective ruthenium-based olefin metathesis catalyst that is considerably more robust than the recently reported (SIMes)(Cl)(RS)RuCH(o-OiPrC6H4) (3a, SIMes = 1,3-dimesityl-4,5-dihydroimidazol-2-ylidene, R = 2,4,6-triphenylbenzene) [J. Am. Chem. Soc., 2013, 135, 3331]. Replacing the chloride of 3a by an isocyanate ligand to give 5a was predicted to increase the stability of the complex considerably, at the same time moderately improving the Z-selectivity. Compound 5a is easily prepared in a two-step synthesis starting from the Hoveyda-Grubbs second-generation catalyst 3. In agreement with the calculations, the isocyanate-substituted 5a appears to be somewhat more Z-selective than the chloride analogue 3a. More importantly, 5a can be used in air, with unpurified and non-degassed substrates and solvents, and in the presence of acids. These are traits that are unprecedented among highly Z-selective olefin metathesis catalysts and also very promising with respect to applications of the new catalyst. This journal is the Partner Organisations 2014.
- Occhipinti, Giovanni,Koudriavtsev, Vitali,Toernroos, Karl W.,Jensen, Vidar R.
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p. 11106 - 11117
(2014/07/21)
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- BMIm-PF6@SiO2 Microcapsules: Particulated ionic liquid as a new material for the heterogenization of catalysts
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A method for the preparation of silica microcapsules containing a high loading of ionic liquids (ILs) is described. The method paves the way to the conversion of ionic liquids into particulated materials, which results in ILs with new properties without changing their molecular structures. The synthesis of these new materials is based on the emulsification of ionic liquids in water, using surfactants or dispersants, and the resulting ionic liquid droplets are then confined in a silica shell formed via interfacial hydrolysis and polycondensation of tetraethoxysilane. This material can be isolated by centrifugation, followed by drying to yield a fine powder of ionic liquid-silica microcapsules, which are water and organic solvents redispersible. These new materials are utilized in the heterogenization of palladium catalyst and then applied in the hydrogenation of alkynes. The catalyst shows chemoselectivity in the hydrogenation of internal alkynes such as 4-octyne. Comparative studies have shown that the same catalyst loses this selectivity when it is applied under homogeneous conditions.
- Weiss, Ester,Dutta, Bishnu,Kirschning, Andreas,Abu-Reziq, Raed
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p. 4781 - 4787
(2014/11/07)
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- METATHESIS CATALYSTS AND METHODS THEREOF
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The present application provides, among other things, novel compounds and methods for metathesis reactions. In some embodiments, a provided compound has the structure of formula I. In some embodiments, the present invention provides methods for preparing a compound of formula I. In some embodiments, the present invention provides metathesis methods comprising providing a compound of formula I.
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Page/Page column
(2014/11/13)
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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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- Simple and highly Z-selective ruthenium-based olefin metathesis catalyst
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A one-step substitution of a single chloride anion of the Grubbs-Hoveyda second-generation catalyst with a 2,4,6-triphenylbenzenethiolate ligand resulted in an active olefin metathesis catalyst with remarkable Z selectivity, reaching 96% in metathesis homocoupling of terminal olefins. High turnover numbers (up to 2000 for homocoupling of 1-octene) were obtained along with sustained appreciable Z selectivity (>85%). Apart from the Z selectivity, many properties of the new catalyst, such as robustness toward oxygen and water as well as a tendency to isomerize substrates and react with internal olefin products, resemble those of the parent catalyst.
- Occhipinti, Giovanni,Hansen, Fredrik R.,T?rnroos, Karl W.,Jensen, Vidar R.
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supporting information
p. 3331 - 3334
(2013/04/23)
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- A well-defined silica-supported tungsten oxo alkylidene is a highly active alkene metathesis catalyst
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Grafting (ArO)2W(i=O)(i=CHtBu) (ArO = 2,6-mesitylphenoxide) on partially dehydroxylated silica forms mostly [(i - SiO)W(i=O)(i=CHtBu) (OAr)] along with minor amounts of [(i - SiO)W(i=O)(CH2tBu) (OAr)2] (20%), both fully ch
- Conley, Matthew P.,Mougel, Victor,Peryshkov, Dmitry V.,Forrest, William P.,Gajan, David,Lesage, Anne,Emsley, Lyndon,Coperet, Christophe,Schrock, Richard R.
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supporting information
p. 19068 - 19070
(2014/01/17)
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- Z -selective ethenolysis with a ruthenium metathesis catalyst: Experiment and theory
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The Z-selective ethenolysis activity of chelated ruthenium metathesis catalysts was investigated with experiment and theory. A five-membered chelated catalyst that was successfully employed in Z-selective cross metathesis reactions has now been found to be highly active for Z-selective ethenolysis at low ethylene pressures, while tolerating a wide variety of functional groups. This phenomenon also affects its activity in cross metathesis reactions and prohibits crossover reactions of internal olefins via trisubstituted ruthenacyclobutane intermediates. In contrast, a related catalyst containing a six-membered chelated architecture is not active for ethenolysis and seems to react through different pathways more reminiscent of previous generations of ruthenium catalysts. Computational investigations of the effects of substitution on relevant transition states and ruthenacyclobutane intermediates revealed that the differences of activities are attributed to the steric repulsions of the anionic ligand with the chelating groups.
- Miyazaki, Hiroshi,Herbert, Myles B.,Liu, Peng,Dong, Xiaofei,Xu, Xiufang,Keitz, Benjamin K.,Ung, Thay,Mkrtumyan, Garik,Houk,Grubbs, Robert H.
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supporting information
p. 5848 - 5858
(2013/05/22)
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- HIGHLY Z-SELECTIVE OLEFINS METATHESIS
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The present invention relates generally to catalysts and processes for the Z-selective formation of internal olefin(s) from terminal olefin(s) via homo-metathesis reactions.
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Page/Page column 18-19
(2011/04/19)
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- Room-temperature Z-selective homocoupling of α-olefins by tungsten catalysts
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3,5-Dimethylphenylimido complexes of tungsten can be prepared using procedures analogous to those employed for other tungsten catalysts, as can bispyrrolide species and MonoAryloxide-Pyrrolide (MAP) species. Homocouplings of 1-hexene, 1-octene, and methyl 10-undecenoate are achieved in 45-89% yield and a Z selectivity of >99% with W(Nar″)(C3H6)(pyr) (OHIPT) as a catalyst. Homocoupling of terminal olefins in the presence of (E)-olefins elsewhere in the molecule also was achieved with excellent selectivity.
- Marinescu, Smaranda C.,Schrock, Richard R.,Mueller, Peter,Takase, Michael K.,Hoveyda, Amir H.
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scheme or table
p. 1780 - 1782
(2011/06/22)
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- Z -selective homodimerization of terminal olefins with a ruthenium metathesis catalyst
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The cross-metathesis of terminal olefins using a novel ruthenium catalyst results in excellent selectivity for the Z-olefin homodimer. The reaction was found to tolerate a large number of functional groups, solvents, and temperatures while maintaining excellent Z-selectivity, even at high reaction conversions.
- Keitz, Benjamin K.,Endo, Koji,Herbert, Myles B.,Grubbs, Robert H.
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supporting information; experimental part
p. 9686 - 9688
(2011/08/05)
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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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- Effect of solvent and temperature on the lithium?bromine exchange of vinyl bromides: Reactions of n -butyllithium and t -butyllithium with (E)-5-bromo-5-decene
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The outcome of reactions of (E)-5-bromo-5-decene (1), a representative vinyl bromide, with t-BuLi or n-BuLi at 0 °C and room temperature, respectively, in a variety of solvent systems has been investigated. Vinyl bromide 1 does not react with t-BuLi in pure heptane; however, the presence of even small quantities of an ether in a predominantly heptane medium resulted in virtually complete consumption of 1 at 0 °C, resulting in nearly the same distribution of products, including 60?80% of (Z)-5-decenyllithium, regardless of the solvent composition. Vinyl bromide 1 reacts slowly with n-BuLi at room temperature in a variety of ether and heptane-ether mixtures to afford a mixture of products including significant quantities of recovered starting material. The results of these experiments demonstrate that lithium?bromine exchange between a vinyl bromide and either t-BuLi or n-BuLi at temperatures significantly above ?78 °C is not an efficient method for the generation of a vinyllithium.
- Bailey, William F.,Luderer, Mark R.,Uccello, Daniel P.,Bartelson, Ashley L.
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experimental part
p. 2661 - 2666
(2010/08/19)
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- Highly Z-selective metathesis homocoupling of terminal olefins
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(Chemical Equation Presented) Mo and W MonoAryloxide-Pyrrolide (MAP) olefin metathesis catalysts can couple terminal olefins to give as high as >98% Z-products in moderate to high yields with as little as 0.2% catalyst. Results are reported for 1-hexene, 1-octene, allylbenzene, allyltrimethylsilane, methyl-10-undecenoate, methyl-9-decenoate, allylB(pinacolate), allylOBenzyl, allylNHTosyl, and allylNHPh. It is proposed that high Z-selectivity is achieved because a large aryloxide only allows metallacyclobutanes to form that contain adjacent cis substituents and because isomerization of Z-product to E-product can be slow in that same steric environment.
- Jiang, Annie J.,Zhao, Yu,Schrock, Richard R.,Hoveyda, Amir H.
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supporting information; experimental part
p. 16630 - 16631
(2010/02/16)
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- Iron-catalyzed alkenylation of Grignard reagents by enol phosphates
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Stereoselective preparation of trisubstituted olefins can be easily performed from an Z/E-mixture of enol phosphates by reacting only the E-isomer with a Grignard reagent in the presence of Fe(acac)3. This procedure combines a kinetic differentiation and a stereoselective reaction. The coupling is very chemoselective in the presence of an alkyl chloride, an ester, a ketone or a nitrile. Georg Thieme Verlag Stuttgart.
- Cahiez, Gerard,Gager, Olivier,Habiak, Vanessa
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experimental part
p. 2636 - 2644
(2009/04/07)
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- Palladium(II)-catalyzed isomerization of olefins with tributyltin hydride
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(Chemical Equation Presented) A new efficient method for the synthesis of geometrically pure (E)-alkenes from (Z)-alkenes is described. The reaction of aryl- or alkyl-substituted (Z)-alkenes with tributyltin hydride and triethylamine in the presence of a catalytic amount of palladium acetate afforded the corresponding (E)-alkenes in good yields.
- In, Su Kim,Guang, Ri Dong,Young, Hoon Jung
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p. 5424 - 5426
(2008/02/07)
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- Metathesis of hex-1-ene in ionic liquids
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The WCl6 + BMIMBF4 and NaReO4 + BMIMCl-AICl3 (BMIM is l-butyl-3-methylimidazolium) systems are effective catalysts for the metathesis of hex-1-ene to form oct-4-ene.
- Vasnev, Alexander V.,Greish, Alexander A.,Kustov, Leonid M.
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- Metathesis of hex-1-ene in ionic liquids catalyzed by WCl6
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Metathesis of hex-1-ene in ionic liquids catalyzed by WCl6 was studied. The metathesis is preceded by isomerization of hex-1-ene to hex-2-ene, from which the main reaction product, viz., oct-4-ene, is derived. The WCl 6-1-butyl-3-methylimidazolium tetrafluoroborate (BMIM·BF 4) system efficiently catalyzes metathesis of linear olefin, the ionic liquid serving as the reaction medium by forming a stable homogeneous catalytic system with WCl6. The yields of the metathesis products increase with increasing reaction temperature. The addition of tin-containing promoters leads to a substantial increase in the reaction rate. In the WCl 6-BMIM·BF4-SnBu4 system, the selectivity of the formation of oct-4-ene is significantly enhanced.
- Vasnev,Greish,Kustov
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p. 2187 - 2191
(2007/10/03)
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- Isomerization of 1-Decene by the Nickel Stearate-Ethylaluminum Chloride Catalytic System
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The influence of the temperature, nature, and concentration of catalyst components on the conversion of 1-decene during its isomerization by the action of a Ni(OCOC17H35)2-(C2H 5)nAlCl3-n (n = 1.0, 1.5) catalyst system was studied. It was shown that the 1-decene conversion increased from 19 to 100 wt% within 60 min as the nickel stearate concentration was increased from 0.00016 to 0.002 mol/l. The conditions of the process that ensure attaining 100% conversion within 5 min were revealed. Under these conditions, a temperature change from 20 to 80°C had no substantial effect on the 1-decene isomerization process. An increase in the ethylaluminum sesquichloride concentration from 0.01 to 0.04 mol/l led to a fourfold growth in the 1-decene isomerization rate. It was found that ethylaluminum dichloride is a more effective cocatalyst than ethylaluminum sesquichloride. IR, 1H NMR, and 13C NMR measurements showed that 1-decene isomerizes in the presence of these catalytic systems into a mixture of all theoretically possible positional and geometrical isomers. Based on the results obtained, the nature of the active sites and the mechanism of 1-decene isomerization are discussed.
- Startseva,Matkovskii,Churkina,Boiko,Knerel'man,Davydova,Troitskii,Aldoshin,Demidov,Shamsutdinov,Il'yasov
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- Alkynylsilanes as convenient precursors for the stereoselective synthesis of (E)-disubstituted alkenes
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Hydromagnesiation of alkynylsilanes 1 gives (Z)-α-silylvinyl Grignard reagents 2, which are reacted with alkyl iodides or aryl iodides in the presence of Cul or Pd(PPh3)4 catalysts to afford (Z)-1,2-disubstituted vinylsilanes 3 in good yields. Intermediates 3 can undergo a desilylation reaction to give (E)-disubstituted alkenes 4 in high yields.
- Zhao, Hong,Cai, Mingzhong
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p. 608 - 610
(2007/10/03)
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- InCl3-Zn. A novel reduction system for the deoxygenative coupling of carbonyl compounds to olefins
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A simple and inexpensive procedure for the deoxygenative homo-coupling and cross-coupling of carbonyl compounds with InCl3-Zn system in dry acetonitrile at ambient pressure is achieved. The procedure gives excellent yields of E-olefinic products.
- Barman,Thakur,Prajapati,Sandhu
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p. 515 - 516
(2007/10/03)
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- Debrominations of vic-Dibromides with Diorganotellurides. 1. Stereoselectivity, Relative Rates, and Mechanistic Implications
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Debrominations of vic-dibromides with diaryl tellurides 1-4 and di-n-hexyl telluride (9) are described. A mechanistic explanation of the debromination is offered which accounts for several key experimental observations: (1) the reaction is highly stereoselective with erythro-dibromides giving trans-olefins and threo-dibromides giving cis-olefins, (2) the reaction is accelerated by more electron-rich diorganotellurides, (3) the reaction is accelerated in a more polar solvent, (4) the reaction is accelerated by the addition of carbocation-stabilizing substituents to the carbons bearing the bromo substituents, and (5) erythro-dibromides are much more reactive than threo-dibromides. It is proposed that bromonium ion formation from the vic-dibromide is slow and rate-determining. Bromonium ion formation is followed by rapid scavenging of "Br-" by the diorganotelluride. The bromonium ion formation provides stereoselectivity and eclipsing interactions lower the reactivity of threo-dibromides. No intermediate species were observed by 1H NMR.
- Butcher, Timothy S.,Zhou, Feng,Detty, Michael R.
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p. 169 - 176
(2007/10/03)
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- Unusual Reactivity of Lithiated 2-Alkylbenzotriazoles
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Treatment of a 2-alkylbenzotriazole (BtCH2R) (2) with LDA at -78 deg C produces rapidly a mixture of a coupling product (BtCHR-CHRBt) (5) and a compound formed from four molecules of the starting material (BtCHR-CHR-CHR-CHRBt) (6).A mixture of 2-methylbenzotriazole and benzophenone, treated with LDA, gives adduct Ph2C(OH)CH2Bt (14) quantitatively whereas benzaldehyde does not react under these conditions. 2-Alkylbenzotriazoles (2) are alkylated at the α-carbon atom when their mixtures with alkyl halides are treated with LDA. - Key Words: Benzotriazoles, 2-alkyl / Lithiation / Alkenes / Radicals
- Katritzky, Alan R.,Wu, Jing,Kuzmierkiewicz, Wojciech,Rachwal, Stanislaw,Balasubramanian, Marudai,Steel, Peter J.
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- Reactions of α-epoxysilanes with organocopper reagents. A stereoselective route to alkenes
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Reactions of α-epoxysilanes with cuprate reagents can be controlled to give β-silyl alcohols as major products. An oxidation, Grignard addition, and elimination sequence then provides alkenes with up to 98% de.
- Chauret, Denise C.,Chong, J. Michael
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p. 3695 - 3698
(2007/10/02)
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