- Extension of surface organometallic chemistry to metal?organic frameworks: Development of a well-defined single site [(≡Zr? O?)W(=O)(CH2TBu)3] olefin metathesis catalyst
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We report here the first step by step anchoring of a W(≡CtBu)(CH2tBu)3 complex on a highly crystalline and mesoporous MOF, namely Zr-NU-1000, using a Surface Organometallic Chemistry (SOMC) concept and methodology. SOMC allowed us to selectively graft the complex on the Zr6 clusters and characterize the obtained single site material using state of the art experimental methods including extensive solid-state NMR techniques and HAADF-STEM imaging. Further FT?IR spectroscopy revealed the presence of a W=O moiety arising from the in situ reaction of the W≡CtBu functionality with the coordinated water coming from the 8-connected hexanuclear Zr6 clusters. All the steps leading to the final grafted molecular complex have been identified by DFT. The obtained material was tested for gas phase and liquid phase olefin metathesis and exhibited higher catalytic activity than the corresponding catalysts synthesized by different grafting methods. This contribution establishes the importance of applying SOMC to MOF chemistry to get well-defined single site catalyst on MOF inorganic secondary building units, in particular the in situ synthesis of W=O alkyl complexes from their W carbyne analogues.
- Thiam, Zeynabou,Abou-Hamad, Edy,Dereli, Busra,Liu, Lingmei,Emwas, Abdul-Hamid,Ahmad, Rafia,Jiang, Hao,Isah, Abdulrahman Adamu,Ndiaye, Papa Birame,Taoufik, Mostafa,Han, Yu,Cavallo, Luigi,Basset, Jean-Marie,Eddaoudi, Mohamed
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supporting information
p. 16690 - 16703
(2020/11/09)
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- Carbonylative, Catalytic Deoxygenation of 2,3-Disubstituted Epoxides with Inversion of Stereochemistry: An Alternative Alkene Isomerization Method
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Reactions facilitating inversion of alkene stereochemistry are rare, sought-after transformations in the field of modern organic synthesis. Although a number of isomerization reactions exist, most methods require specific, highly activated substrates to achieve appreciable conversion without side product formation. Motivated by stereoinvertive epoxide carbonylation reactions, we developed a two-step epoxidation/deoxygenation process that results in overall inversion of alkene stereochemistry. Unlike most deoxygenation systems, carbon monoxide was used as the terminal reductant, preventing difficult postreaction separations, given the gaseous nature of the resulting carbon dioxide byproduct. Various alkyl-substituted cis- A nd trans-epoxides can be reduced to trans- A nd cis-alkenes, respectively, in >99:1 stereospecificity and up to 95% yield, providing an alternative to traditional, direct isomerization approaches.
- Lamb, Jessica R.,Hubbell, Aran K.,MacMillan, Samantha N.,Coates, Geoffrey W.
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supporting information
p. 8029 - 8035
(2020/05/01)
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- Photocatalytic Transfer Hydrogenolysis of Allylic Alcohols on Pd/TiO2: A Shortcut to (S)-(+)-Lavandulol
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We report herein a regio- and stereoselective photocatalytic hydrogenolysis of allylic alcohols to form unsaturated hydrocarbons employing a palladium(II)-loaded titanium oxide; the reaction proceeds at room temperature under light irradiation without stoichiometric generation of salt wastes. Olefin and saturated alcohol moieties tolerated the reaction conditions. Hydrogen atoms were selectively incorporated into less sterically congested carbons of the allylic functionalities. This protocol allowed a short-step synthesis of (S)-(+)-lavandulol from (R)-(?)-carvone by avoiding otherwise necessary protection/deprotection steps.
- Takada, Yuki,Caner, Joaquim,Kaliyamoorthy, Selvam,Naka, Hiroshi,Saito, Susumu
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supporting information
p. 18025 - 18032
(2017/12/08)
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- METHOD FOR PRODUCING ORGANIC COMPOUND
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PROBLEM TO BE SOLVED: To provide a method of subjecting a compound having on one carbon atom a carbon atom constituting a carbon-carbon double bond and a functional group such as a hydroxyl group to a reductive reaction condition and producing an organic compound having the functional group substituted with a hydrogen atom. SOLUTION: There is provided a method for producing a compound represented by a formula (50) from a raw material compound represented by a formula (10). The method includes a step of irradiating a reaction system with light, the reaction system comprising the raw material compound, a hydrogen source compound, and a catalyst having a palladium component supported by a carrier containing titanium oxide. (R11 to R15 are a hydrogen atom, a hydrocarbon group having 1 to 40 carbon atoms which may have a cyclic structure or a derivative group thereof, or a heteroatom-containing group having 1 to 20 carbon atoms which may have a cyclic structure or a derivative group thereof; and R16 is a hydrogen atom, a hydrocarbon group having 1 to 40 carbon atoms or an acyl group having 1 to 20 carbon atoms which may have a cyclic structure, or -CH(CH2OH)2).) COPYRIGHT: (C)2015,JPO&INPIT
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Paragraph 0111-0112; 0115
(2018/10/16)
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- β-Diketiminate complexes of Group 4: Active complexes for the isomerization of α-olefins and the polymerization of propylene towards elastomeric polypropylene
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The β-diketiminate lithium ligand [{N(SiMe3)C(Ph)} 2CH][Li] reacted with Group 4 metal salts (Ti and Zr) to yield the complexes [{N(SiMe3)C(Ph)}2CH] 2TiCl2 (5) and [{N(SiMe3)C(Ph)} 2CH][N(SiMe3)C(Ph)NC(Ph)CH(SiMe3)] ZrCl2 (6). The crystal structure of 6 shows that one of the two ketamidinate ligands undergoes an isomerization to the corresponding substituted benzamidinate. A mechanism for the catalyzed isomerization of the β-diketiminate ligand is presented. Complex 5 was found to be active in the polymerization of propylene, producing remarkably high-molecular weight (>100,000 g mol-1) elastomeric polymer, whereas the zirconium complex was found inactive. Complex 5, and surprisingly complex 6, were found to be active catalysts, in the presence of MAO (methylalumoxane), for the isomerization of aliphatic olefins (1-octene, allylbenzene). Each complex catalyzed the olefins by different mechanisms. Kinetic studies for the isomerization of allylbenzene by complex 5 show that the reaction rate follows a first order in both catalyst and olefin concentrations with Δ H ?=14.7(4) kcal mol-1 and Δ S ?=-33(1) e.u. These findings support the epimerization mechanism of the last inserted monomer that is proposed for as the primary cause for the elastomeric properties of polypropylene produced by this complex. In addition, we show how complementary isomerization studies of α-olefins shed light on the polymerization mechanism.
- Shaviv, Ella,Botoshansky, Mark,Eisen, Moris S.
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p. 165 - 180
(2007/10/03)
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- Intramolecular Dehydration of β-Hydroxyalkylphosphonic Acid Monoesters. A Novel Type of Olefin Formation
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The title reaction using dicyclohexylcarbodiimide (DCC) gave stereospecifically the corresponding olefins in good yields via tetracoordinate 1,2-oxaphosphetanes.Use of more than one equivalent of DCC afforded better yields of the olefin.
- Kawashima, Takayuki,Nakamura, Mio,Nakajo, Akira,Inamoto, Naoki
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p. 1483 - 1486
(2007/10/02)
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- Alkyliron and Alkylcobalt Reagents, VII. - On the Substitution of the Halogen of Alkenyl Chlorides, Alkenyl Fluorides, and Alkynyl Halides by Reagents of the Type R4MLi2 (M = Fe, Co)
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Me4FeLi2 and Me4CoLi2, which are favourable reagents for the substitution of Br in alkenyl bromides, also proved to be favourable for the substitution of the halogen in alkenyl chlorides (yields 68-99 percent; nearly complete retention of configuration in the case of Me4FeLi2), β-fluorostyrene (best yield 92 percent), and 1-fluoronaphthalene (best yield 47 percent).Me4FeLi2 differentiates between various alkenyl chlorides in 1:1 competition experiments better than Me4CoLi2 and is the optimal reagent for the substitution of halogen in 1-chloro-2-phenylethyne (12), 1-bromo-2-phenylethyne (13), and 1-chloro-3-phenoxypropyne (15) by methyl (yields 70, 46, and 80 percent, respectively).Substitution of the halogen in 12 by the n-butyl, n-octyl, and phenyl residue is better achieved by the catalytic systems RMgBr + 2.5 mol percent FeCl2 (R = nBu, nOct, Ph; yields 75, 63, and 96 percent, respectively) than by the reagents nBu4FeLi2, nBu4Fe(MgBr)2, nOct4Fe(MgBr)2, or Ph4Fe(MgBr)2 (yields 18-28 percent). Key Words: Iron, organo complexes / Cobalt, organo complexes
- Kauffmann, Thomas,Saelker, Reiner,Voss, Karl-Uwe
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p. 1447 - 1452
(2007/10/02)
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- A Bridged Tetrahydrophosphole Ylide Derived from 9-Phenylphosphabicyclononane: A Reagent for E-Selective Wittig Reactions
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The bicyclic ylide 4 reacts with aldehydes to afford the E-alkenes.Selectivity is 94 - 6percent E for unbranched aldehydes, but the selectivity decreases with increasing α-branching.Ylide 4 is the first E-selective, nonstabilized ylide that allows efficient utilization of the P-alkyl substituent.
- Vedejs, E.,Peterson, M. J.
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p. 1985 - 1986
(2007/10/02)
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- THE HYDRIDOPENTACYANOCOBALTATE ANION INDUCED DEOXYGENATION OF ALLYLIC ALCOHOLS USING β-CYCLODEXTRIN AS A PHASE TRANSFER AGENT
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β-Cyclodextrin promotes the deoxygenation of allylic alcohols to olefins using hydrogen and the in situ generated hydridopentacyanocobaltate anion.Internal olefins, of trans-stereochemistry, are the principal reaction products (i. e., no cis-products are formed).
- Lee, Jong-Tae,Alper, Howard
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p. 4101 - 4104
(2007/10/02)
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- Organoborane-Catalyzed Hydroalumination of Terminal Allenes
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Organoborane-catalyzed hydroalumination of terminal allenes with dichloroaluminum hydride gives rise to the corresponding allylaluminum compounds under mild conditions with high regioselectivity.
- Nagahara, Shigeru,Maruoka, Keiji,Doi, Yoshiharu,Yamamoto, Hisashi
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p. 1595 - 1598
(2007/10/02)
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- AIR-STABLE BINUCLEAR ALKOXYTUNGSTEN COMPLEXES AS CATALYST PRECURSORS FOR OLEFIN METATHESIS
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The use of the air-stable complexes tetrachlorobis(μ-methoxy)bis(methanolo)dimethoxyditungsten (1) and tetrachlorobis(μ-ethoxy)tetraethoxyditungsten (2) as catalyst precursors for the metathesis of 1-octene is described.Using mild conditions, the latter was converted to 7-tetradecene (4) in fair yields when diethylaluminum chloride (3) was used as a cocatalyst.Product stereoselectivity was 4/1 in favor of the trans isomer.The reaction was also shown to be efficient for the production of 2-nonenes.
- Savard, Jacques,Alper, Howard
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p. 2483 - 2486
(2007/10/02)
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- Untersuchungen von Polymerisation- und Metathese-Reaktionen XIV. Darstellung heterogener, bimetallischer Metathese-Katalysatoren durch Reaktionen von Carbin-Wolfram-Komplexen des Fischer-Typs mit reduziertem Phillips-Katalysator
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Reactions of Fischer-type carbyne tungsten complexes X(CO)nWCPh (X=Cl, Br, I, n=4; X=Cp, n=2) with reduced Phillips catalyst, a chromium(II) compound surface-bound to silica, yield heterogeneous bimetallic metathesis catalysts for alkenes.The reactions probably proceed via a cycloaddition of the WC-carbyne bond with the chromium(II) atoms to give dimetallacyclopropene derivatives.The bimetallic catalysts formed by reaction with the halogeno substituted carbyne complexes are very active alkene metathesis catalysts, as demonstrated by the reaction with 1-octene.The original polymerisation activity towards 1-alkenes of the surface-bound chromium(II) atoms disappeared after reaction with carbyne complexes.
- Weiss, Karin,Denzner, Michael
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p. 273 - 280
(2007/10/02)
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- Regioselective Synthesis of Therminal Olefins from Alkanes via Rhodium-Catalyzed C-H Activation
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Pentane and decane were regioselectively transformed into 1-butene and 1-nonene with the simultaneous formation of acetaldehyde by photocatalysis in the presence of RhCl(CO)(PMe3)2 under carbon monoxide.
- Sakakura, Toshiyasu,Hayashi, Teruyuki,Tanaka, Masato
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p. 859 - 862
(2007/10/02)
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- "Counter" Phase Transfer Catalysis by Water-soluble Phosphine Complexes. Catalytic Reduction of Allyl Chlorides and Acetates with Sodium Formate in Two-phase Systems
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In the reduction of allyl chlorides and acetates with sodium formate in a heptane-water two-phase system, water-soluble palladium complexes function as a novel type of catalyst which transports the substrate into the aqueous phase and causes it to react with sodium formate.
- Okano, Tamon,Moriyama, Yoshiyuki,Konishi, Hisatoshi,Kiji, Jitsuo
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p. 1463 - 1466
(2007/10/02)
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- HOMOALLYLIC SUBSTITUTION REACTIONS OF LITHIUM DIALKYL CUPRATES WITH CYCLOPROPYLCARBINYL HALIDES: MECHANISTIC CONSIDERATIONS
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Highly reactive lithium dialkyl cuprates and 1-bromo-1-cyclopropylalkanes, 4, react to give good yields of the homoallylic substitution product, 6.Less reactive organocuprates react with 4 to give mixtures of 6 and the direct substitution product 7.These results are consistent with a copper(I) radical intermediate which undergoes facile rearrangement prior to reductive coupling.
- Hrubiec, Robert T.,Smith, Michael B.
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p. 1457 - 1468
(2007/10/02)
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- Diastereoselectivity in the Alkylation of Enolates having an Adjacent Silyl Group
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The methylation of open-chain enolates having an adjacent silyl group is highly diastereoselective in favour of the isomer (2) having the silyl and methyl groups trans on the carbon chain; protonation of the corresponding enolate, already carrying the methyl group, gives the other diastereoisomer (3), but with somewhat lower diastereoselectivity.
- Bernhard, Werner,Fleming, Ian,Waterson, David
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- THE RELATIVE STEREOCHEMISTRY OF SOME α-METHYL-β-SILYLCARBONYL COMPOUNDS PRODUCED BY THE DIASTEREOSELECTIVE ALKYLATION OF β-SILYLENOLATES
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Conjugate addition of lithium bis(dimethylphenylsilyl)cuprate to methyl cinnamate (1), to 4-phenylbut-3-en-2-one (4), and to dec-3-en-2-one (15), followed by methylation of the intermediate enolate, gives largely one diastereoisomer of the α-methyl-β-silylcarbonyl compound (the β-silyl ester (3), 3-methyl-4-dimethyl(phenyl)silyl-4-phenylbutan-2-one (5), and 4-dimethyl(phenyl)silyl-3-methyldecan-3-one (16), respectively).The relative configurations of the two chiral centres in these products are proved to be (RR,SS), (RR,SS), and (RS,SR), respectively, by conversion of the ester 3 into the ketone 5, and by Baeyer-Villiger oxidation of the ketone 5, its diastereoisomer (RS,SR)-3-methyl-4-dimethyl(phenyl)silyl-4-phenylbutan-2-one (8), and the ketone 16 to the corresponding acetates ((RR,SS)-1-phenyl-1-dimethyl(phenyl)silylprop-2-yl acetate (9), (RS,SR)-1-phenyl-1-dimethyl(phenyl)silylprop-2-yl acetate (12), and (RR,SS)-3-dimethyl(phenyl)silylnon-2-yl acetate (17)).Fluoride ion-catalysed elimination of the silyl and acetate groups is not stereospecific when the silyl group is benzylic (9 and 12), but is stereospecifically anti for the saturated acetate (17).Reduction of the acetates 9, 12 and 17 followed by syn-Peterson elimination gives the alkenes E-phenylpropene (11), Z-phenylprop-1-ene (14) and E-non-2-ene (19).
- Bernhard, Werner,Fleming, Ian
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p. 281 - 288
(2007/10/02)
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- Electrochemical Reduction and Oxidation of Allenes
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The allenes 1 - 3 are reduced on mercury at -2.17 V (sce) (1), -3.12 V (2), and below -3.30 V (3); they are oxidized on glassy carbon at 1.25, 1.65 V (1), 1.75 V (2), and above 2.25 V (3).In the preparative reduction 1 forms, depending on the workup, 86percent of 1,1,3,3-tetraphenyl-1-propene (6a) or up to 50percent of aldehyde 9, a formylation product of the rearranged radical anion intermediate; on carboxylation of the electrolyte 54percent of carboxylic acid 8 are formed.The allene 2 is hydrogenenated to give 30 percent of (E)-1-phenyl-1-propene (10) and hydrodimerized to form 30percent of yield s in methylene dichloride/methanol 61 - 73percent of 2-chloro-1,1,3-triphenylidene (13), which is probably formed by chlorine, that is electrochemically generated from methylene chloride.In methanol/dioxane 13 is not obtained but 71percent of indanone 16 are produced.The oxidation of 2 and 3 is unselective; due to follow-up oxidations many products are formed in low yield.
- Schlegel, Guenter,Schaefer, Hans J.
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p. 960 - 969
(2007/10/02)
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- Syntheses a l'aide de sulfones. XVIII. Utilisation des disulfones-1,1 pour la synthese stereoselective de composes olefiniques
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2-Alkenyl-1,1-disulfones 4 are readily available in excellent yields by condensation of aldehydes with bisaryl or bisalkylsulfonylmethanes in the presence of piperidine acetate and molecular sieves at room temperature.A small amount of the 1-alkenyl isomer is also found when the aldehyde is α-substituted but it can be converted into the 2-alkenyl isomer by base catalysed equilibration.The 2-alkenyl-1,1-disulfones display only E geometry whereas E allylic monosulfones are difficult to isolate in a state of stereochemical purity (about 20percent of the Z isomer at equilibrium (8)).Alkylation is readily performed: treatment of 4 and 6 by sodium hydride in dimethylformamide and then by methyl iodide gives disulfones 5 E and 7 in 78-95percent yields.The alkylation of 4 (R=Et) by butyl iodide gives 70percent of 5 E(R=Et, R'=n-Bu) resulting from alkylation at the α position and 8percent of 3 (R=Et, R'=n-Bu) resulting from alkylation at the γ position.The α isomer is readily purified by crystallization.Reduction of disulfones 4 or 5 by aluminium amalgam leads quantitatively to allylic sulfones 2E or 8E.Olefins 9E are obtained upon total reduction of disulfones 4 or 5 by lithium in ethylamine at -78 deg C but in the case of disulfones 5 the olefins 9E are contaminated by isomers 10E and 10Z.
- Cuvigny, Therese,Penhoat, Catherine Herve Du,Julia, Marc
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- Stereoselectivity in the Cross-metathesis of Oct-1-ene and cis- or trans-Oct-2-ene
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The yields and the initial ratios of cis and trans geometries of non-2-ene, tridec-6-ene, or tetradec-7-ene, formed by the cross-metathesis of oct-1-ene and cis- or trans-oct-2-ene catalyzed by tungsten hexachloride-tetraphenyltin (A), hexaphenoxytungsten-ethylaluminium dichloride (B), or tungsten hexachloride-triethylaluminium (C), have been correlated to the interactions of alkyl substituents on tungstacyclobutane.The results strongly suggest that the 2,4-interaction, between the alkyl substituent on C2 and the tungsten moiety, plays an important part in determining the distribution of products.
- Uchida, Akira,Hinenoya, Masayoshi,Yamamoto, Toshihiko
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p. 1089 - 1092
(2007/10/02)
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- Anwendungen der Phasentransfer-Katalyse 17. Wittig-Reaktionen in verschiedenen Zweiphasen-Systemen
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EINE vergleichende Untersuchung von Wittig-Reaktionen unter Phasentransfer-Katalyse (PTC) bei verschiedenen Bedingungen wurde durchgefuehrt.Es erwies sich als unnoetig, ausser den Phosphoniumsalzen einen PTC-Katalysator zu verwenden.Mechanistische Konsequenzen dieses Befundes werden diskutiert.Als ein besonders geeignetes Basensystem stellte sich Kalium-tert-butoxid in Benzol heraus.Erstmals gelang die Umzetzung von Ketonen und aliphatischen Aldehyden.Einige sehr hohe Literaturausbeuten von PTC-Wittig-Reaktionen konnten unter praeparativen Bedingungen nicht reproduziert werden.
- Dehmlow, Eckehard V.,Barahona-Naranjo, Simon
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p. 1748 - 1762
(2007/10/02)
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- THE EFFECT OF CROWN ETHER ON STERIC HINDRANCE TO BASE APPROACH IN BIMOLECULAR ELIMINATION: EVIDENCE AGAINST CLUMP AGGREGATE MODEL OF ION-PAIRED ALKOXIDE BASE
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The effect of 18-crown-6-ether upon geometrical orientation and rates was investigated in tert-C4H9OK-tert-C4H9OH promoted anti-elimination from two homologous series of tosylates, RCH2CHOTsC5H11 and RCHOTsCH2C5H11 (R = H, CH3, C2H5, n-C3H5, iso-C3H7, tert-C4H9).Steric requirements of the cis- and trans-stereoselective base species operating in the reaction in the absence and in the presence of the crown ether, respectively, have been assessed.An unambiguous distinction has been made between two pending models of the cis-stereoselective (ion-paired) base.
- Pankova, Magdalena,Zavada, Jiri
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p. 3150 - 3159
(2007/10/02)
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