- Hydrogenation reaction method
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The invention relates to a hydrogenation reaction method, and belongs to the technical field of organic synthesis. The hydrogenation reaction method provided by the invention comprises the following steps: carrying out a hydrogen transfer reaction on a hydrogen acceptor compound, pinacol borane and a catalyst in a solvent in the presence of proton hydrogen, so that the hydrogen acceptor compound is subjected to a hydrogenation reaction; the catalyst is one or more than two of a palladium catalyst, an iridium catalyst and a rhodium catalyst; the hydrogen acceptor compound comprises one or morethan two functional groups of carbon-carbon double bonds, carbon-carbon triple bonds, carbon-oxygen double bonds, carbon-nitrogen double bonds, nitrogen-nitrogen double bonds, nitryl, carbon-nitrogentriple bonds and epoxy. The method is mild in reaction condition, easy to operate, high in yield, short in reaction time, wide in substrate application range, suitable for carbon-carbon double bonds,carbon-carbon triple bonds, carbon-oxygen double bonds, carbon-nitrogen double bonds, nitrogen-nitrogen double bonds, nitryl, carbon-nitrogen triple bonds and epoxy functional groups, good in selectivity and high in reaction specificity.
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Paragraph 0034; 0157-0160
(2020/05/14)
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- Generalized Chemoselective Transfer Hydrogenation/Hydrodeuteration
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A generalized, simple and efficient transfer hydrogenation of unsaturated bonds has been developed using HBPin and various proton reagents as hydrogen sources. The substrates, including alkenes, alkynes, aromatic heterocycles, aldehydes, ketones, imines, azo, nitro, epoxy and nitrile compounds, are all applied to this catalytic system. Various groups, which cannot survive under the Pd/C/H2 combination, are tolerated. The activity of the reactants was studied and the trends are as follows: styrene'diphenylmethanimine'benzaldehyde'azobenzene'nitrobenzene'quinoline'acetophenone'benzonitrile. Substrates bearing two or more different unsaturated bonds were also investigated and transfer hydrogenation occurred with excellent chemoselectivity. Nano-palladium catalyst in situ generated from Pd(OAc)2 and HBPin extremely improved the TH efficiency. Furthermore, chemoselective anti-Markovnikov hydrodeuteration of terminal aromatic olefins was achieved using D2O and HBPin via in situ HD generation and discrimination. (Figure presented.).
- Wang, Yong,Cao, Xinyi,Zhao, Leyao,Pi, Chao,Ji, Jingfei,Cui, Xiuling,Wu, Yangjie
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supporting information
p. 4119 - 4129
(2020/08/10)
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- Hydrogenation of Alkenes Catalyzed by a Non-pincer Mn Complex
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Hydrogenation of substituted styrenes and unactivated aliphatic alkenes by molecular hydrogen has been achieved using a Mn catalyst with a non-pincer, picolylphosphine ligand. This is the second reported example of alkene hydrogenation catalyzed by a Mn complex. Mechanistic studies showed that a Mn hydride formed by H2 activation in the presence of a base is the catalytically active species. Based on experimental and DFT studies, H2 splitting is proposed to occur via a metal-ligand cooperative pathway involving deprotonation of the CH2 arm of the ligand, leading to pyridine dearomatization.
- Rahaman, S. M. Wahidur,Pandey, Dilip K.,Rivada-Wheelaghan, Orestes,Dubey, Abhishek,Fayzullin, Robert R.,Khusnutdinova, Julia R.
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p. 5912 - 5918
(2020/10/30)
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- Combined Photoredox/Enzymatic C?H Benzylic Hydroxylations
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Chemical transformations that install heteroatoms into C?H bonds are of significant interest because they streamline the construction of value-added small molecules. Direct C?H oxyfunctionalization, or the one step conversion of a C?H bond to a C?O bond, could be a highly enabling transformation due to the prevalence of the resulting enantioenriched alcohols in pharmaceuticals and natural products,. Here we report a single-flask photoredox/enzymatic process for direct C?H hydroxylation that proceeds with broad reactivity, chemoselectivity and enantioselectivity. This unified strategy advances general photoredox and enzymatic catalysis synergy and enables chemoenzymatic processes for powerful and selective oxidative transformations.
- Betori, Rick C.,May, Catherine M.,Scheidt, Karl A.
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supporting information
p. 16490 - 16494
(2019/11/03)
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- Room Temperature Iron-Catalyzed Transfer Hydrogenation and Regioselective Deuteration of Carbon-Carbon Double Bonds
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An iron catalyst has been developed for the transfer hydrogenation of carbon-carbon multiple bonds. Using a well-defined β-diketiminate iron(II) precatalyst, a sacrificial amine and a borane, even simple, unactivated alkenes such as 1-hexene undergo hydrogenation within 1 h at room temperature. Tuning the reagent stoichiometry allows for semi- and complete hydrogenation of terminal alkynes. It is also possible to hydrogenate aminoalkenes and aminoalkynes without poisoning the catalyst through competitive amine ligation. Furthermore, by exploiting the separate protic and hydridic nature of the reagents, it is possible to regioselectively prepare monoisotopically labeled products. DFT calculations define a mechanism for the transfer hydrogenation of propene with nBuNH2 and HBpin that involves the initial formation of an iron(II)-hydride active species, 1,2-insertion of propene, and rate-limiting protonolysis of the resultant alkyl by the amine N-H bond. This mechanism is fully consistent with the selective deuteration studies, although the calculations also highlight alkene hydroboration and amine-borane dehydrocoupling as competitive processes. This was resolved by reassessing the nature of the active transfer hydrogenation agent: experimentally, a gel is observed in catalysis, and calculations suggest this can be formulated as an oligomeric species comprising H-bonded amine-borane adducts. Gel formation serves to reduce the effective concentrations of free HBpin and nBuNH2 and so disfavors both hydroboration and dehydrocoupling while allowing alkene migratory insertion (and hence transfer hydrogenation) to dominate.
- Espinal-Viguri, Maialen,Neale, Samuel E.,Coles, Nathan T.,MacGregor, Stuart A.,Webster, Ruth L.
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supporting information
p. 572 - 582
(2019/01/08)
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- Polymethylhydrosiloxane reduction of carbonyl function catalysed by titanium tetrachloride
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Reduction of aromatic aldehydes and ketones into the corresponding methylene derivatives by polymethylhydrosiloxane in the presence of titanium tetrachloride as catalyst was achieved in good to excellent yields ranging from 55-90%. The reaction took place under relatively mild conditions and smoothly led to the desired target molecules in the presence of other functional groups such as halogens, hydroxyl, nitro and methoxy groups. However, in the reduction of the substrate with two methoxy groups in close proximity (1,2-positions), the reaction necessitated a larger amount of the titanium catalyst and a longer reaction time to complete the reduction of the carbonyl function due to a likely complex formation of titanium tetrachloride with the methoxy groups.
- Jumbam, Ndze D.,Makaluza, Siyavuya,Masamba, Wayiza
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p. 179 - 184
(2018/04/20)
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- Selective Cobalt-Catalyzed Reduction of Terminal Alkenes and Alkynes Using (EtO)2Si(Me)H as a Stoichiometric Reductant
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While attempting to effect Co-catalyzed hydrosilylation of β-vinyl trimethylsilyl enol ethers, we discovered that, depending on the silane, solvent, and the method of generation of the reduced cobalt catalyst, a highly efficient and selective reduction or hydrosilylation of an alkene can be achieved. This paper deals with this reduction reaction, which has not been reported before in spite of the huge research activity in this area. The reaction, which uses the air-stable [2,6-bis(aryliminoyl)pyridine)]CoCl2 activated by 2 equiv of NaEt3BH as the catalyst (0.001-0.05 equiv) and (EtO)2SiMeH as the hydrogen source, is best run at ambient temperature in toluene and is highly selective for the reduction of simple unsubstituted 1-alkenes and the terminal double bonds in 1,3- and 1,4-dienes, β-vinyl ketones, and silyloxy dienes. The reaction is tolerant of various functional groups such as bromide, alcohol, amine, carbonyl, di- or trisubstituted double bonds, and water. Highly selective reduction of a terminal alkyne to either an alkene or alkane can be accomplished by using stoichiometric amounts of the silane. Preliminary mechanistic studies indicate that the reaction is stoichiometric in the silane and both hydrogens in the product come from the silane.
- Raya, Balaram,Biswas, Souvagya,Rajanbabu
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p. 6318 - 6323
(2016/09/09)
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- Tetrahydroxydiboron-Mediated Palladium-Catalyzed Transfer Hydrogenation and Deuteriation of Alkenes and Alkynes Using Water as the Stoichiometric H or D Atom Donor
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There are few examples of catalytic transfer hydrogenations of simple alkenes and alkynes that use water as a stoichiometric H or D atom donor. We have found that diboron reagents efficiently mediate the transfer of H or D atoms from water directly onto unsaturated C-C bonds using a palladium catalyst. This reaction is conducted on a broad variety of alkenes and alkynes at ambient temperature, and boric acid is the sole byproduct. Mechanistic experiments suggest that this reaction is made possible by a hydrogen atom transfer from water that generates a Pd-hydride intermediate. Importantly, complete deuterium incorporation from stoichiometric D2O has also been achieved.
- Cummings, Steven P.,Le, Thanh-Ngoc,Fernandez, Gilberto E.,Quiambao, Lorenzo G.,Stokes, Benjamin J.
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supporting information
p. 6107 - 6110
(2016/06/09)
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- An unprecedented anionic Ln-MOF with a cage-within-cage motif: Spontaneous reduction and immobilization of ion-exchanged Pd(II) to Pd-NPs in the framework
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An unprecedented microporous anionic Ln-MOF, [Me2NH2]24[Tb12(TATB)16(HCOO)12]·12DMF·48H2O (1) (H3TATB = 4,4′,4′′-s-triazine-2,4,6-tribenzoic acid), which is a rare cage-within-cage structure through interpenetration rather than covalent bonding, has been synthesized. Compound 1 contains a 3D net which is constructed using a large and a small Ln-carboxylate cage alternately arranged by sharing faces with each other. Interpenetration of two identical 3D nets occurs in such a way that each small cage of one net is encapsulated within the large cage of the other and vice versa, generating an overall 3D double-walled cage framework. Such interpenetration creates a unique structure of double-shelled hollow space to accommodate Pd nanoparticles (Pd-NPs), which could effectively prevent Pd-NPs from aggregation and leaching. Moreover, the ion-exchanged Pd(ii) embedded in the framework can be readily reduced at room temperature with no requirement of any chemical or thermal treatments, affording Pd-NPs with uniform size and even distribution. As a result, the as-prepared Pd-NPs@1 exhibits excellent activity and cycling stability for the hydrogenation of styrene and its derivatives.
- Han, Yun-Hu,Tian, Chong-Bin,Lin, Ping,Du, Shao-Wu
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p. 24525 - 24531
(2015/12/09)
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- A mild and efficient rhenium-catalyzed transfer hydrogenation of terminal olefins using alcoholysis of amine-borane adducts as a reducing system
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[ReBr2(NO)(CH3CN)(PTA)2] (PTA = 1, 3, 5-triaza-7-phosphaadamantane) catalyzes the alcoholysis of ammonia-borane and amine-boranes and the catalytic transfer hydrogenations of various terminal olefins. Excellent yields were achieved at 70 °C in isopropanol using tBuOK as a co-catalyst affording TOF values up to 396 h-1.
- Dong, Hailin,Berke, Heinz
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experimental part
p. 1803 - 1808
(2011/06/19)
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- MEDICINAL COMPOSITIONS
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The present invention relates to an agent for the prophylaxis or treatment of pain, an agent for suppressing activation of osteoclast, and an inhibitor of osteoclast formation, which contains a p38 MAP kinase inhibitor and/or a TNF-α production inhibitor.
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- Substituted 1,3-thiazole compounds, their production and use
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(1) A 1,3-thiazole compound of which the 5-position is substituted with a 4-pyridyl group having a substituent including no aromatic group or (2) a 1,3-thiazole compound of which the 5-position is substituted with a pyridyl group having at the position adjacent to a nitrogen atom of the pyridyl group a substituent including no aromatic group has an excellent p38 MAP kinase inhibitory activity.
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- CONCOMITANT DRUGS
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The present invention relates to a pharmaceutical agent containing one or more kinds of a p38 MAP kinase inhibitor and/or a TNF-α production inhibitor and one or more kinds of drugs selected from the group consisting of (1) a non-steroidal antiinflammator
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- JNK INHIBITOR
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The present invention relates to a c-Jun N-terminal kinase inhibitor containing an azole compound (I) substituted by a nitrogen-containing aromatic group having substituent(s)(except a compound represented by the formula: ) or a salt thereof or a prodrug thereof.
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Page/Page column 78
(2010/02/07)
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- p38MAP KINASE INHIBITORS
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A 1,3-thiazole compound substituted at the 5-position by a pyridyl group optionally having substituent(s) has a superior p38 MAP kinase inhibitory activity and TNF-α production inhibitory activity.
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- Conformational studies by dynamic NMR. 74. Stereomutations of the conformational enantiomers in peri-substituted 1-acylnaphthalenes
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Naphthalenes bearing an acyl and a phenyl group in a peri relationship give rise to a pair of enantiomers in the temperature range where the rotations of the acyl group are slow. Such enantiomers were observed by means of low temperature NMR spectra in chiral environments. The barrier to rotation for the acyl substituents, that causes the interconversion of the enantiomers, was demonstrated to be lower than that for the phenyl group. In an appropriately synthesized derivative it was possible to measure the two barriers that were found equal to 10.4 and 15.9 kcal mol-1, respectively. The barriers for the acyl group rotation increase regularly (from 9.5 to 13.2 kcal mol-1) with the increasing dimension of the RCO groups (R = Me, Et, Pr(i), Bu(t)). When a bromine atom replaces the phenyl group, the enantiomerization barrier for the corresponding acyl derivatives increases significantly.
- Lunazzi, Lodovico,Mazzanti, Andrea,Alvarez, Anna Munoz
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p. 3200 - 3206
(2007/10/03)
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- Direct Formation of (Haloaryl)copper Nucleophiles from Haloiodobenzenes and Active Copper
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(o-Halophenyl)-, (m-halophenyl)-, and (p-halophenyl)copper reagents have been formed in moderate to high yields at room temperature from active copper and the corresponding haloiodobenzenes.These reagents have been cross-coupled with a variety of alkyl and acyl halides to produce the respective haloarenes and haloaryl ketones.Remarkably, (o-fluorophenyl)- and (o-chlorophenyl)copper are produced in good yields by this procedure without undergoing elimination to form benzyne making this approach a convenient method for generating o-halophenyl nucleophiles.
- Ebert, Greg W.,Pfennig, Deborah R.,Suchan, Scott D.,Donovan, Thomas A.,Aouad, Emmanuel,et al.
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p. 2361 - 2364
(2007/10/02)
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- Synthesis of (+)-(R)-6-ethyl-2,3-dihydro-2-methyl-4H-pyran-4-one -sex-pheromone component of the male swift moth Hepialus hecta L.
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The synthesis of the male swift moth sex pheromone component, (+)-(R)-6-ethyl-2,3-dihydro-2-methyl-4H-pyran-4-one (6), from ethyl aniline and (S)-2-methyloxirane is described.
- Sanders,Wager,Seidel
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- Bromination of alkylbenzenes in organic solvents. Substrate and position selectivity and effects of substituents
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The relative reactivity and the orientation of the entering group in the reaction of bromine with alkylbenzenes (C1-C4 alkyl groups, the last two with normal and iso structures) in organic solvents (acetic acid, acetic anhydride, nitromethane) under polythermal conditions (25-75 deg C) are determined mainly by the steric effects of the substituents.Nathan-Baker position and substrate effects are observed.Correlations close to linear are observed between the orientation (in the form of log 2P/O, where P and O are the relative amounts of the isomers in their reaction mixture) and the purely steric constants of the alkyl groups Es0.The substrate selectivity depends nonlinearly and inversely on Es0.The sensitivity of the orientation to change in the steric characteristics of the substituents shows an extremal dependence on the temperature with a maximum at about 50 deg C.
- Krylov, E. N.,Paramonova, O. K.
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p. 149 - 154
(2007/10/02)
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- Alkylation of Arenes with Ethylene over H-ZSM-5 and Modernite-H Catalysis
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Attempts were made to alkylate acetophenone, benzene, benzonitrile, bromobenzene, chlorobenzene, ethylbenzene, fluorobenzene, iodobenzene, methoxybenzene, nitrobenzene, toluene and α,α,α-trifluorotoluene with ethylene over H-ZSM-5 and mordenite-H catalysts at 400 and 250 deg C, respectively.Over H-ZSM-5 benzene, bromobenzene, chlorobenzene, ethylbenzene and toluene gave monoethylarenes as the major product (95-100percent) with the para product as the dominant isomer (87-95percent).Over mordenite-H benzene, bromobenzene, chlorobenzene and toluene reacted.The monoethylarenes were again the major product (85-95percent) but the isomer distributions were close to the thermodynamically controlled ones due to isomerization of the initially formed products.Over H-ZSM-5 the results indicated the reaction to be of a Friedel-Crafts type.It was proposed that the product composition was determined by the chemical reaction, not by the rate of diffusion of the products.
- Akervold, Idar,Bakke, Jan M.,Steinsvik, Eirik
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p. 437 - 444
(2007/10/02)
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- Low-Resolution Microwave Studies of Substituted Ethyl- and Isopropylbenzenes
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A single conformation exists in ethylbenzenes with the ethyl C-C bond lying in a plane orthogonal to the benzene ring.This conclusion results from the observation that asymmetrically substituted ethylbenzenes each display only a single band series in low-resolution microwave (LRMW) spectra whereas any other conformation of the ethylphenyl fragment would result in two spectroscopically distinguishable species.LRMW spectra of isopropylbenzene derivatives display three spectroscopically distinguishable band series, two of which correspond to the conformation with the methine C-H bond eclipsed with the benzene ring and syn or anti with respect to an unsymmetrical phenyl substituent.The third series is much more intense, has a B + C value which is the average of the syn and anti forms, and is consistent with the superposition of spectra of torsionally excited species.
- True, Nancy S.,Farag, Maya, S.,Bohn, Robert K.,MacGregor, Malcolm A.,Radhakrishnan, J.
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p. 4622 - 4627
(2007/10/02)
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- Carbanion Rearrangements by Intramolecular 1,ω Proton Shifts, III. The Reaction of 2-, 3-, 4-, and 5-Phenylalkyllithium Compounds
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Upon addition of THF to a solution of 4-phenylbutyllithium (2) in diethyl ether a rapid intramolecular 1,4 proton shift takes place with the formation of 1-phenylbutyllithium (5).Similarly, although somewhat more slowly, 5-phenylpentyllithium (82) rearranges to 1-phenylpentyllithium (83) via 1,5 proton transfer.The corresponding rearrangements by 1,2 or 1,3 hydrogen shifts, however, starting with 2-phenylethyllithium (1) and 3-phenylpropyllithium (54), respectively, were not detected.With 3-phenylpropyllithium (54) a slow intramolecular 1,5 transfer an ortho proton is observed instead, yielding o-propylphenyllithium (100).The corresponding 1,6 shift with 4-phenylbutyllithium (2) was also detected in a minor amount in addition to the 1,4 proton shift already mentioned.There is no indication, however, for a 1,4 transfer of an ortho proton in 2-phenylethyllithium (1).The reaction products in this case can be exclusively explained by intermolecular transmetallation reactions.All ω-phenylalkyllithium compounds under investigation show interesting side and secondary reactions being rather different in deuterated solvents and in deuteriumfree solvents, respectively, due to the isotope effects.The analysis of the products is accomplished by 1H-NMR spectroscopy and, after derivatization, with the help of a GC-MS-combination.Stereoelectronic reasons are made responsible for the failure of the intramolecular 1,2 and 1,3 proton shift in these systems.
- Maercker, Adalbert,Passlack, Michael
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p. 540 - 577
(2007/10/02)
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