- Solvent-controlled intramolecular excimer emission from organosilicon derivatives of naphthalene
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New mono-, bis- and tetra-fluorophoric organosilicon naphthalene derivatives, that are able to form intramolecular excimers have been synthesized and characterized. The synthesized compounds show only monomeric fluorescence in dilute solutions of common organic solvents, but exhibit relatively strong excimer-like emission in DMSO-water and THF-water mixtures. In all cases, the intensity of excimer fluorescence increases with increasing water content and decreases with increasing temperature. Fully and partially overlapping excimer conformations have been modeled by DFT-based calculations. Properties of different intramolecular excimers in an ensemble of four naphthalene molecules linked to a cyclotetrasiloxane ring in an all-cis arrangement are considered.
- Alfimov, M. V.,Anisimov, A. A.,Belova, A. S.,Ionov, D. S.,Kononevich, Yu. N.,Muzafarov, A. M.,Safonov, A. A.,Sazhnikov, V. A.,Shchegolikhina, O. I.
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Read Online
- Modular Ni(0)/Silane Catalytic System for the Isomerization of Alkenes
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Alkenes are used ubiquitously as starting materials and synthetic targets in all areas of chemistry. Controlling their geometry and position along a chain is vital to their reactivity and properties yet remains challenging. Alkene isomerization is an atom-economical process to synthesize targeted alkenes, and selectivity can be controlled using transition metal catalysts. The development of mild, selective isomerization reactivity has enabled efficient tandem catalytic systems for the remote functionalization of alkenes, a process in which a starting alkene is isomerized to a new position prior to the functionalization step. The key challenges in developing isomerization catalysts for remote functionalization applications are (i) a lack of modularity in the catalyst structure and (ii) the requirement of nonmodular and/or harsh additives during catalyst activation. We address both challenges with a modular (NHC)Ni(0)/silane catalytic system (NHC, N-heterocyclic carbene), demonstrating the use of triaryl silanes and readily accessible (NHC)Ni(0) complexes to form the proposed active (NHC)(silyl)Ni-H species in situ. We show that modification of the steric and electronic nature of the catalyst via modification of the ancillary ligand and silane partner, respectively, is easily achieved, creating a uniquely versatile catalytic system that is effective for the formation of internal alkenes with high yield and selectivity for the E-alkene. The use of silanes as mild activators enables isomerization of substrates with a variety of functional groups, including acid-labile groups. The broad substrate scope, enabled by catalyst design, makes this catalytic system a strong candidate for use in tandem catalytic applications. Preliminary mechanistic studies support a Ni-H insertion/elimination pathway.
- Chang, Alison Sy-Min,Cook, Amanda K.,Kawamura, Kiana E.,Martin, Daryl J.,Morris, Parker T.,Smith, Haley M.
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supporting information
p. 486 - 496
(2022/03/02)
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- METHOD FOR PRODUCING ARENE COMPOUNDS AND ARENE COMPOUNDS PRODUCED BY THE SAME
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Provided is a method for producing (alkyl)arene compounds represented by Formulae 3-1, 3-2, and 3-3 by the Friedel-Crafts alkylation reaction of alkyl halide compounds and arene compounds using organic phosphine compounds as a catalyst.
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Paragraph 0033
(2021/06/26)
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- Direct oxidative isoperfluoropropylation of terminal alkenes: Via hexafluoropropylene (HFP) and silver fluoride
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A copper-mediated oxidative isoperfluoropropylation of unactivated terminal alkenes with commercially available hexafluoropropylene (HFP) has been developed. With operational simplicity of the procedure and broad substrate applicability, this strategy pro
- Wang, Xiaojun,Wu, Yongming
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supporting information
p. 1877 - 1880
(2018/02/23)
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- Palladium-catalyzed oxidative allylation of bis[(pinacolato)boryl]methane: Synthesis of homoallylic boronic esters
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A palladium-catalyzed oxidative allylation of bis[(pinacolato)boryl]methane to afford the corresponding homoallylic organoboronic esters with moderate to excellent yields is reported. This novel transformation provides an efficient strategy for the construction of homoallylic organoboronic esters in one step with a broad substrate scope. It is proposed that the palladium-catalyzed oxidative allylic C-H bond activation process may be involved in the catalytic cycle.
- Li, Chunsheng,Li, Meng,Li, Jianxiao,Wu, Wanqing,Jiang, Huanfeng
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supporting information
p. 66 - 69
(2017/12/27)
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- Cross-Coupling Reactions of Aryldiazonium Salts with Allylsilanes under Merged Gold/Visible-Light Photoredox Catalysis
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A method for the cross-coupling reactions of aryldiazonium salts with trialkylallylsilanes via merged gold/photoredox catalysis is described. The reaction is proposed to proceed through a photoredox-promoted generation of an electrophilic arylgold(III) intermediate that undergoes transmetalation with allyltrimethylsilane to form allylarenes.
- Akram, Manjur O.,Mali, Pramod S.,Patil, Nitin T.
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supporting information
p. 3075 - 3078
(2017/06/23)
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- Stereospecific Deoxygenation of Aliphatic Epoxides to Alkenes under Rhenium Catalysis
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The combination of a catalytic amount of Re2O7 and triphenyl phosphite as a reductant is effective for the deoxygenation of unactivated aliphatic epoxides to alkenes. The reaction proceeds stereospecifically with variously substituted epoxides under neutral conditions and is compatible with various functional groups. Protection and deprotection of a double bond functionality using an epoxide are shown as an example of the current rhenium-catalyzed deoxygenation protocol. The effect of reductants for the stereoselectivity has also been studied, indicating that the use of electron-deficient phosphines or phosphites is the key for the stereospecific deoxygenation. (Chemical Equation Presented).
- Nakagiri, Takuya,Murai, Masahito,Takai, Kazuhiko
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supporting information
p. 3346 - 3349
(2015/07/15)
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- Copper(I) 2-hydroxyethoxide-promoted cross-coupling of aryl- and alkenyldimethylsilanes with organic halides
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Fluoride-free cross-coupling of aryl- and alkenyldimethylsilanes with organic halides proceeded in the presence of monocopper(I) alkoxide of ethylene glycol.
- Takeda, Takeshi,Obata, Ryosuke,Muramatsu, Daisuke,Takeda, Yuichiro,Tsubouchi, Akira
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supporting information
p. 15156 - 15158
(2014/12/11)
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- A facile and convenient sequential homobimetallic catalytic approach towards β-methylstyrenes. A one-pot Stille cross-coupling/isomerization strategy
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An efficient one-pot synthetic approach towards β-methylstyrenes is reported. The transformation, based on sequential homobimetallic catalysis, involves a Stille cross-coupling reaction between aryl halides and allyltributylstannane, followed by an in situ palladium-catalyzed conjugative isomerization. The reaction was optimized, and the best results were obtained with 10 mol% Pd(PPh3)2Cl2, 8.0 equiv. LiCl, and 0.5 equiv. PPh3 in diglyme at 130 °C for 12 h. It was demonstrated that the reaction tolerates a wide variety of functional groups. This journal is the Partner Organisations 2014.
- Simonetti, Sebastian O.,Larghi, Enrique L.,Kaufman, Teodoro S.
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p. 3735 - 3743
(2014/06/09)
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- Generation of stoichiometric ethylene and isotopic derivatives and application in transition-metal-catalyzed vinylation and enyne metathesis
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Ethylene is one of the most important building blocks in industry for the production of polymers and commodity chemicals. 13C- and D-isotope-labeled ethylenes are also valuable reagents with applications ranging from polymer-structure determination, reaction-mechanism elucidation to the preparation of more complex isotopically labeled compounds. However, these isotopic derivatives are expensive, and are flammable gases, which are difficult to handle. We have developed a method for the controlled generation of ethylene and its isotopic variants including, for the first time, fully isotopically labeled ethylene, from simple alkene precursors by using Ru catalysis. Applying a two-chamber reactor allows both the synthesis of ethylene and its immediate consumption in a chemical transformation permitting reactions to be performed with only stoichiometric amounts of this two carbon olefin. This was demonstrated in the Ni-catalyzed Heck reaction with aryl triflates and benzyl chlorides, as well as Ru-mediated enyne metathesis. Why more when less works! A method for the controlled generation of ethylene including the fully isotopically labeled derivative is described, as well as their use in three transition-metal-catalyzed reactions. Applying a two-chamber reactor, only stoichiometric amounts of ethylene are required, which allows the simple installment of deuterium and 13C in the product (see scheme).
- Min, Geanna K.,Bjerglund, Klaus,Kramer, Soren,Gogsig, Thomas M.,Lindhardt, Anders T.,Skrydstrup, Troels
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supporting information
p. 17603 - 17607
(2014/01/06)
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- Palladium nanoparticles in glycerol: A versatile catalytic system for C-X bond formation and hydrogenation processes
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Palladium nanoparticles stabilised by tris(3-sulfophenyl)phosphine trisodium salt in neat glycerol have been synthesised and fully characterised, starting from both Pd(II) and Pd(0) species. The versatility of this innovative catalytic colloidal solution has been proved by its efficient application in C-X bond formation processes (X=C, N, P, S) and C-C multiple bond hydrogenation reactions. The catalytic glycerol phase could be recycled more than ten times, preserving its activity and selectivity. The scope of each of these processes has demonstrated the power of the as-prepared catalyst, isolating the corresponding expected products in yields higher than 90%. The dual catalytic behaviour of this glycerol phase, associated to the metallic nanocatalysts used in wet medium (molecular- and surface-like behaviour), has allowed attractive applications in one-pot multi-step transformations catalysed by palladium, such as C-C coupling followed by hydrogenation, without isolation of intermediates using only one catalytic precursor. Copyright
- Chahdoura, Faouzi,Pradel, Christian,Gomez, Montserrat
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supporting information
p. 3648 - 3660
(2014/01/06)
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- Palladium-catalyzed allyl cross-coupling reactions with in situ generated organoindium reagents
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Inter- and intramolecular palladium-catalyzed allyl cross-coupling reactions, using allylindium generated in situ from allyl halides and indium, is demonstrated. Allylindium compounds may be effective nucleophilic coupling partners in palladium-catalyzed cross-coupling reactions. A variety of allyl halides, such as allyl iodide, allyl bromide, crotyl bromide, prenyl bromide, geranyl bromide, and 3-bromocyclohexene afforded the allylic cross-coupling products in good to excellent yields. Stereochemistry of the double bond is retained in the allylic cross-coupling reactions. Electrophilic cross-coupling partners, such as aryl and vinyl halides, dibromoolefin, alkynyl iodide, and aryl and vinyl triflates participate in these reactions. The presence of various substituents, such as n-butyl, ketal, acetyl, ethoxycarbonyl, nitrile, N-phenylamido, nitro, and chloride groups on the aromatic ring of electrophilic coupling partners showed little effect on the efficiency of the reactions. The present conditions work equally well for not only intermolecular but also intramolecular palladium-catalyzed cross-coupling reactions. These methods provide an efficient synthetic method for the introduction of an allyl group, which can be easily further functionalized to afford an sp2- and sp-hybridized carbon. The present method complements existing synthetic methods as a result of advantageous features such as easy preparation and handling, thermal stability, high reactivity and selectivity, operational simplicity, and low toxicity of allylindium reagents.
- Lee, Kooyeon,Kim, Hyunseok,Mo, Juntae,Lee, Phil Ho
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scheme or table
p. 2147 - 2157
(2011/10/31)
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- Nickel-catalyzed heck-type reactions of benzyl chlorides and simple olefins
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Nickel-catalyzed intermolecular benzylation and heterobenzylation of unactivated alkenes to provide functionalized allylbenzene derivatives are described. A wide range of both the benzyl chloride and alkene coupling partners are tolerated. In contrast to analogous palladium-catalyzed variants of this process, all reactions described herein employ electronically unbiased aliphatic olefins (including ethylene), proceed at room temperature, and provide 1,1-disubstituted olefins over the more commonly observed 1,2-disubstituted olefins with very high selectivity.
- Matsubara, Ryosuke,Gutierrez, Alicia C.,Jamison, Timothy F.
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supporting information; experimental part
p. 19020 - 19023
(2011/12/21)
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- Chemoselective transfer of allyl or phenyl group from allyl(phenyl)germanes in Pd-catalyzed reactions with aryl halides
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Treatment of chloro(phenyl)germanes with allylmagnesium bromide yielded allyl(phenyl)germanes. Coupling of the allyl- (phenyl)germanes with aryl halides in 1,4-dioxane in the presence of aqueous NaOH and Pd catalyst resulted in Heck-type transfer of the allyl group providing the corresponding allylated aryls. On the other hand, reaction of allyl(phenyl)germanes with SbF5 intercalated in graphite in toluene and subsequent treatment of the resulting germanyl fluorides with TBAF generates reactive hypervalent fluorogermanates that undergo Stille-like Pd-catalyzed cross-coupling with aryl halides in wet toluene to provide biaryls.
- Pitteloud, Jean-Philippe,Liang, Yong,Wnuk, Stanislaw F.
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supporting information; experimental part
p. 967 - 969
(2011/12/05)
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- Polymer-supported pentaethylene glycol as a facile heterogeneous catalyst for nucleophilic fluorination
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Polymer-supported pentaethylene glycols (PSpentaEG) as promising catalysts for nucleophilic fluorination with alkali metal fluoride (MF) could significantly enhance the nucleophilicity of MF and provide simple purification and recycling in the reaction. F
- Jadhav, Vinod H.,Jang, Seung Ho,Jeong, Hwan-Jeong,Lim, Seok Tae,Sohn, Myung-Hee,Chi, Dae Yoon,Kim, Dong Wook
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supporting information; experimental part
p. 3740 - 3743
(2010/11/05)
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- Introduction of allyi and prenyl side-chains into aromatic systems by suzuki cross-coupling reactions
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This paper reports some studies aiming at the developement of a general protocol useful for the synthesis of allyl- and prenylaromatic compounds. The first part deals with, the preparation of boron reagents like arylboronic acids and their pinacol esters as well as of pinacol allyl- and prenylboronates. The second part of the paper is devoted to the use of these boron reagents in Suzuki-Miyaura cross-coupling reactions leading to allylation and prenylation of aromatic compounds. Of the six methods studied, the most promising re-suits were obtained by using the Pd2(dba)3-catalyzed reactions of arylboronic acids with allyl and prenyl bromides, that lead to the products of cross coupling in high yields (average 87%), and the reactions of aryl trifluoroborates with allyl and prenyl bromides catalyzed by Pd(OAc)2 that lead to the products of coupling in all cases in high yields (average 82%).
- Gerbino, Dario C.,Mandolesi, Sandra D.,Schmalz, Hans-Guenther,Podesta, Julio C.
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experimental part
p. 3964 - 3972
(2010/02/27)
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- Palladium-catalyzed cross-couplings of allylic phosphates
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A range of palladium-catalyzed cross-coupling reactions can be performed using allylic phosphates as electrophiles. Both conventional heating and microwave irradiation can be used.
- Maslak, Veselin,Tokic-Vujosevic, Zorana,Saicic, Radomir N.
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supporting information; experimental part
p. 1858 - 1860
(2009/07/19)
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- Palladium-catalyzed cross-coupling reactions of potassium alkenyltrifluoroborates with organic halides in aqueous media
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Potassium vinyl and alkenyltrifluoroborates are cross-coupled with aryl and heteroaryl bromides using 1 mol % Pd loading of 4-hydroxyacetophenone oxime derived palladacycle or Pd(OAc)2 as precatalysts, K 2CO3 as base, and TBAB as additive and water reflux under conventional or microwave heating to afford styrenes, stilbenoids, and alkenylbenzenes. These borates can be cross-coupled diastereoselectively with allyl and benzyl chlorides using KOH as base in acetone-water (3:2) at 50°C and 0.1 mol % Pd loading, giving the corresponding 1,4-dienes and allylarenes, respectively. These simple phosphine-free reaction conditions allow the palladium recycling from the aqueous phase during up to five runs by extractive separation of the products, which contain 58-105 ppm of Pd.
- Alacid, Emilio,Najera, Carmen
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supporting information; experimental part
p. 2321 - 2327
(2009/07/18)
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- Room-temperature palladium-catalyzed allyl cross-coupling reaction with boronic acids using phosphine-free hydrazone ligands
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Palladium-catalyzed allyl cross-coupling reaction of allylic acetates with a variety of boronic acids at room temperature using a catalytic amount of Pd(OAc)2 with phosphine-free hydrazone as a ligand gave the allylbenzene derivatives in good yields.
- Mino, Takashi,Kajiwara, Kenji,Shirae, Yoshiaki,Sakamoto, Masami,Fujita, Tsutomu
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experimental part
p. 2711 - 2715
(2009/04/11)
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- Palladium(0)-catalyzed direct cross-coupling reaction of allylic alcohols with aryl- and alkenylboronic acids
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Allylic alcohols can be used directly for the palladium(0)-catalyzed allylation of aryl- and alkenylboronic acids with a wide variety of functional groups. A triphenylphosphine-ligated palladium catalyst turns out to be most effective for the cross-coupling reaction and its low loading (less than 1 mol%) leads to formation of the coupling product in high yield. The Lewis acidity of the organoboron reagents and poor leaving ability (high basicity) of the hydroxyl group are essential for the cross-coupling reaction. The reaction process is atom-economical and environmentally benign, because it needs neither preparation of allyl halides and esters nor addition of stoichiometric amounts of a base. Furthermore, allylic alcohols containing another unsaturated carbon-carbon bond undergo arylative cyclization reactions leading to cyclopentane formation. The Royal Society of Chemistry.
- Tsukamoto, Hirokazu,Uchiyama, Tomomi,Suzuki, Takamichi,Kondo, Yoshinori
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supporting information; experimental part
p. 3005 - 3013
(2009/02/03)
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- Xantphos as an efficient ligand for palladium-catalyzed cross-coupling reactions of aryl bromides and triflates with allyl acetates and indium
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(Chemical Equation Presented) Xantphos was found to be an efficient ligand for palladium-catalyzed allyl cross-coupling reactions of aryl bromides and triflates with allylindium reagents generated in situ from allyl acetates and indium. These reactions occur in high yield with good functional group tolerance.
- Seomoon, Dong,Phil, Ho Lee
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p. 1165 - 1168
(2008/09/18)
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- Cross-coupling of aromatic bromides with allylic silanolate salts
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The sodium salts of allyldimethylsilanol and 2-butenyldimethylsilanol undergo palladium-catalyzed cross-coupling with a wide variety of aryl bromides to afford allylated and crotylated arenes. The coupling of both silanolates required extensive optimization to deliver the expected products in high yields. The reaction of the allyldimethylsilanolate takes place at 85°C in 1,2-dimethoxyethane with allylpalladium chloride dimer (2.5 mol %) to afford 73-95% yields of the allylation products. Both electron-rich and sterically hindered bromides reacted smoothly, whereas electron-poor bromides cross-coupled in poor yield because of a secondary isomerization to the 1-propenyl isomer (and subsequent polymerization). The 2-butenyldimethylsilanolate (E/Z, 80:20) required additional optimization to maximize the formation of the branched (γ-substitution) product. A remarkable influence of added alkenes (dibenzylideneacetone and norbornadiene) led to good selectivities for electron-rich and electron-poor bromides in 40-83% yields. However, bromides containing coordinating groups (particularly in the ortho position) gave lower, and in one case even reversed, selectivity. Configurationally homogeneous (E)-silanolates gave slightly higher γ-selectivity than the pure (Z)-silanolates. A unified mechanistic picture involving initial γ-transmetalation followed by direct reductive elimination or σ-π isomerization can rationalize all of the observed trends.
- Denmark, Scott E.,Werner, Nathan S.
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supporting information; experimental part
p. 16382 - 16393
(2009/05/08)
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- Pd(OAc)2/P(cC6H11) 3-catalyzed allylation of aryl halides with homoallyl alcohols via retro-allylation
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Allylations of aryl halides take place upon treatment of tertiary homoallyl alcohols with aryl halides in the presence of cesium carbonate and a palladium catalyst. The allylation reaction would consist of the following steps: (1) oxidative addition of ar
- Iwasaki, Masayuki,Hayashi, Sayuri,Hirano, Koji,Yorimitsu, Hideki,Oshima, Koichiro
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p. 4463 - 4469
(2008/02/04)
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- Inter- and intramolecular palladium-catalyzed allyl cross-coupling reactions using allylindium generated in situ from allyl acetates, indium, and indium trichloride
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Inter- and intramolecular palladium-catalyzed ally! cross-coupling reactions using allylindium generated in situ by treatment of allyl acetates with indium and indium trichloride in the presence of Pd0 catalyst and nBuNMe2 in DMF were successfully demonstrated. Allylindium species generated in situ by reductive transmetalation of π- allylpalladium(II) complexes, obtained from a variety of allyl acetales in the presence of Pd0 catalyst together with indium and indium trichloride, were found to be capable of acting as effective nucleophilic coupling partners in Pd-catalyzed cross-coupling reactions. A variety of allyl acetates such as but-l-en-3-yl acetate, crotyl acetate, and 2-methylallyl acetate afforded the corresponding allylic compounds in good yields in cross-coupling reactions. Various electrophilic cross-coupling partners such as aryl iodides and vinyl bromides and triflates participate in these reactions. Not only intermolecular but also intramolecular Pd-catalyzed cross-coupling reactions work equally well to produce the desired allylic coupling products in good yields.
- Seomoon, Dong,Lee, Kooyeon,Kim, Hyunseok,Lee, Phil Ho
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p. 5197 - 5206
(2008/02/10)
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- Palladium-catalyzed stereo- and regiospecific allylation of aryl halides with homoallyl alcohols via retro-allylation: Selective generation and use of σ-allylpalladium
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Treatment of tertiary homoallyl alcohol with aryl halide under palladium catalysis resulted in the transfer of the allyl moiety of the homoallyl alcohol to aryl halide and yielded the corresponding cross-coupling product stereo- and regiospecifically. The
- Hayashi, Sayuri,Hirano, Koji,Yorimitsu, Hideki,Oshima, Koichiro
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p. 2210 - 2211
(2007/10/03)
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- Sodium dithionite initiated addition of 1-bromo-1-chloro-2,2,2-trifluoroethane to allylaromatics. Facile synthesis of conjugated dienes substituted with terminal CF3 group
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Sodium dithionite effectively promotes the addition of 1-bromo-1-chloro-2,2,2-trifluoroethane to the terminal double bond of allylbenzenes 1. The reactions proceeded in MeCN/H2O to give a 3:1 mole ratio of diastereoisomers of 1-(2-bromo-4-chloro-5,5,5-trifluoropentyl)benzenes 2 as the main products together with small amounts of its reductive debromination products 3. Total yields of 2 and 3 were dependent on the nature of the aromatic ring substituents in 1. Treatment of adducts 2 with DBU in refluxing hexanes resulted in double dehydrohalogenation affording, in good yields, conjugated dienes 4 (1,1,1-trifluoro-5-phenyl-2,4-pentadienes) terminated with the CF3 group at the one end and the phenyl group at the opposite end. These dienes were found to be sufficiently reactive to undergo Diels-Alder condensation with active dienophiles to give trifluoromethylated carbocycles. The reactions of CF3CHClBr with allylheterocycles were less successful and lead to low yields of mixtures of hardly separable compounds or to polymeric resins.
- Ignatowska, Jolanta,Dmowski, Wojciech
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p. 720 - 729
(2008/03/28)
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- Intermolecular heck-type coupling of aryl iodides and allylic acetates
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(Chemical Equation Presented) A palladium-catalyzed arylation of allylic acetates followed by β-acetoxy elimination was shown to produce Heck-type coupling products. Optimal reaction conditions employed ligand-free palladium on carbon in the presence of tetrabutylammonium chloride, a trialkylamine base, and water.
- Mariampillai, Brian,Herse, Christelle,Laufens, Mark
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p. 4745 - 4747
(2007/10/03)
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- Method for producing Grignard compounds
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The invention relates to a process for preparing Grignard compounds of the formula I. The invention additionally relates to compounds of the formula I and to polymer-bound compounds of the formula Ia. The invention further relates to the use of the process for preparing substance libraries and to the use of the compounds of the formulae I and Ia in chemical synthesis.
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Page/Page column 11
(2008/06/13)
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- Method of preparing organomagnesium compounds
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The present invention is directed to a reagent for use in the preparation of organomagnesium compounds as well as to a method of preparing such organomagnesium compounds. The present invention furthermore provides a method of preparing functionalized or unfunctionalized organic compounds as well as the use of the reagents of the present invention in the preparation of organometallic compounds and their reaction with electrophiles. Finally, the present invention is directed to the use of lithium salts - LiY in the preparation of organometallic compounds and their reactions with electrophiles and to an organometallic compound which is obtainable by the disclosed method.
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Page/Page column 15
(2010/02/14)
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- Semivolatile and volatile compounds in combustion of polyethylene
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The evolution of semivolatile and volatile compounds in the combustion of polyethylene (PE) was studied at different operating conditions in a horizontal quartz reactor. Four combustion runs at 500 and 850°C with two different sample mass/air flow ratios and two pyrolytic runs at the same temperatures were carried out. Thermal behavior of different compounds was analyzed and the data obtained were compared with those of literature. It was observed that α,ω-olefins, α-olefins and n-paraffins were formed from the pyrolytic decomposition at low temperatures. On the other hand, oxygenated compounds such as aldehydes were also formed in the presence of oxygen. High yields were obtained of carbon oxides and light hydrocarbons, too. At high temperatures, the formation of polycyclic aromatic hydrocarbons (PAHs) took place. These compounds are harmful and their presence in the combustion processes is related with the evolution of pyrolytic puffs inside the combustion chamber with a poor mixture of semivolatile compounds evolved with oxygen. Altogether, the yields of more than 200 compounds were determined. The collection of the semivolatile compounds was carried out with XAD-2 adsorbent and were analyzed by GC-MS, whereas volatile compounds and gases were collected in a Tedlar bag and analyzed by GC with thermal conductivity and flame ionization detectors.
- Font, Rafael,Aracil, Ignacio,Fullana, Andrés,Conesa, Juan A.
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p. 615 - 627
(2007/10/03)
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- Palladium(0)-catalyzed direct cross-coupling reaction of allyl alcohols with aryl- and vinyl-boronic acids
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Allyl alcohols can be directly used for the palladium-catalyzed allylation of aryl- and vinyl-boronic acids without the aid of a base.
- Tsukamoto, Hirokazu,Sato, Masanori,Kondo, Yoshinori
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p. 1200 - 1201
(2007/10/03)
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- Palladium-indium-indium(III) chloride-mediated allyl cross-coupling reactions using allyl acetates
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Allylindiums in situ generated by reductive transmetalation of π-allylpalladium(II) complexes, obtained from allyl acetates and palladium(0) catalyst, with indium and indium(III) chloride are effective nucleophilic cross-coupling partners in Pd-catalyzed allyl cross-coupling reactions with a variety of electrophilic cross-coupling partners.
- Lee, Phil Ho,Seomoon, Dong,Lee, Kooyeon,Kim, Sundae,Kim, Hyunseok,Kim, Hyun,Shim, Eunkyong,Lee, Miae,Lee, Seokju,Kim, Misook,Sridhar, Madabhushi
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p. 1641 - 1645
(2007/10/03)
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- Cobalt-catalyzed direct electrochemical cross-coupling between aryl or heteroaryl halides and allylic acetates or carbonates
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The electroreduction of a mixture of functionalized aromatic or heteroaromatic bromides or chlorides and allylic compounds such as acetates or carbonates in an electrochemical cell fitted with a sacrificial iron anode affords, in the presence of cobalt halide associated with pyridine as ligand in acetonitrile or DMF, the corresponding coupling product in good yields.
- Gomes, Paulo,Gosmini, Corinne,Perichon, Jacques
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p. 1142 - 1145
(2007/10/03)
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- Trimethyl phosphite as a trap for alkoxy radicals formed from the ring opening of oxiranylcarbinyl radicals. Conversion to alkenes. Mechanistic applications to the study of C-C versus C-O ring cleavage
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Trimethyl phosphite, (MeO)3P, is introduced as an efficient and selective trap in oxiranylcarbinyl radical (2) systems, formed from haloepoxides 8-13 under thermal AIBN/n-Bu3SnH conditions at about 80 °C. Initially, the transformations of 8-13, in the absence of phosphite, to allyl alcohol 7 and/or vinyl ether 5 were measured quantitatively (Table 1). Structural variations in the intermediate oxiranylcarbinyl (2), allyloxy (3), and vinyloxycarbinyl (4) radicals involve influences of the thermodynamics and kinetics of the C-O (2 → 3, k1) and C-C (2 → 4, k2) radical scission processes and readily account for the changes in the amounts of product vinyl ether (5) and allyl alcohol (7) formed. Added (MeO)3P is inert to vinyloxycarbinyl radical 4 and selectively and rapidly traps allyloxy radical 3, diverting it to trimethyl phosphate and allyl radical 6. Allyl radicals (6) dimerize or are trapped by n-Bu3SnH to give alkenes, formed from haloepoxides 8, 9, and 13 in 69-95% yields. Intermediate vinyloxycarbinyl radicals (4), in the presence or absence of (MeO)3P, are trapped by n-Bu3SnH to give vinyl ethers (5). The concentrations of (MeO)3P and n-Bu3SnH were varied independently, and the amounts of phosphate, vinyl ether (5), and/or alkene from haloepoxides 10, 11, and 13 were carefully monitored. The results reflect readily understood influences of changes in the structures of radicals 2-4, particularly as they influence the C-O (k1) and C-C (k2) cleavages of intermediate oxiranylcarbinyl radical 2 and their reverse (k-1, k-2). Diversion by (MeO)3P of allyloxy radicals (3) from haloepoxides 11 and 12 fulfills a prior prediction that under conditions closer to kinetic control, products of C-O scission, not just those of C-C scission, may result. Thus, for oxiranylcarbinyl radicals from haloepoxides 11, 12, and 13, C-O scission (k1, 2 → 3) competes readily with C-C cleavage (k2, 2 → 4), even though C-C scission is favored thermodynamically.
- Ding, Bangwei,Bentrude, Wesley G.
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p. 3248 - 3259
(2007/10/03)
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- Pd-Catalyzed Cross-Coupling of Haloarenes and Chloroarene-Cr(CO) 3 Complexes with Stabilized Vinyl- and Allylaluminium Reagents
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The palladium-catalyzed cross-coupling of intramolecularly stabilized divinyl- and diallylaluminium compounds 1 and 2 with haloarenes and chloroarene-Cr(CO)3 complexes has been studied. The coupling products were obtained in high yields (up to
- Schumann, Herbert,Kaufmann, Jens,Schmalz, Hans-Günther,B?ttcher, Andreas,Gotov, Battsengel
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p. 1783 - 1788
(2007/10/03)
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- Highly efficient allyl cross-coupling reactions of allylindiums with organic electrophiles
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This paper describes highly efficient allyl cross-coupling reactions of allylindiums with organic electrophiles such as aryl and vinyl triflates, vinyl halides, dibromoolefin, and alkynyl iodide. The reactions were carried out using 4 mol % Pd(PPh3)4 in the presence of 3 equiv of LiCl in DMF at 100 °C under a nitrogen atmosphere. Allylindium, generated from the reaction of 1 equiv of indium with 1.5 equiv of allyl halide, gave the best result as a coupling partner. The present method is mild and simple to apply, and it produces a diverse range of allylic compounds in good to excellent yields.
- Lee, Kooyeon,Lee, Jinsung,Lee, Phil Ho
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p. 8265 - 8268
(2007/10/03)
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- Palladium-catalyzed cross-coupling reactions of in situ generated allylindium reagents with aryl halides
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(equation presented) X = Br, I In situ generated allylindium reagents from the reaction of 1 equiv of indium with 1.5 equiv of allyl halides could be effective cross-coupling partners in palladium-catalyzed cross-coupling reactions to aryl halides. The best results were obtained with 2% Pd2dba3CHCl3 and 16% Ph3P in the presence of 3 equiv of LiCl in DMF at 100 °C.
- Lee, Phil Ho,Sung, Sun-Young,Lee, Kooyeon
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p. 3201 - 3204
(2007/10/03)
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- Selective halogen - Magnesium exchange reaction via organomagnesium ate complex
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Halogen-magnesium exchange of various aryl halides is achieved with a magnesium ate complex at low temperatures. Tributylmagnesate (nBu3MgLi) induces facile iodine-magnesium exchange at -78 °C. Dibutylisopropylmagnesate (iPrnBu2MgLi) is more reactive than nBu3MgLi, and this reagent accomplishes selective bromine-magnesium exchange at -78 °C. This procedure is utilized for the preparation of various polyfunctionalized arylmagnesium species. The exchange of alkenyl halides using this method proceeds with retention of configuration of the double bond.
- Inoue,Kitagawa,Shinokubo,Oshima
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p. 4333 - 4339
(2007/10/03)
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- Halogen-magnesium exchange via trialkylmagnesates for the preparation of aryl- and alkenymagnesium reagents
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Significantly better than simple Grignard reagents are the trialkylmagnesium-ate complexes in the halogen-metal exchange reaction of aryl or alkenyl halides to the corresponding magnesates (see reaction scheme). The subsequent reaction of these ate complexes with electrophiles proceeds in good to excellent yields, and a number of functional groups (FG) can be tolerated.
- Kitagawa, Kazuya,Inoue, Atsushi,Shinokubo, Hiroshi,Oshima, Koichiro
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p. 2481 - 2483
(2007/10/03)
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- Characterization of the combustion products of polyethylene
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Polyethylene (PE) was burned in a tube-type furnace with an air flow at a temperature of 600~900°C. Combustion products were collected with glass wool, glass fiber filter, and XAD-2 adsorbent. The analysis of the products was performed with GC-FID and GC-MSD. At low temperature, hydrocarbons were the major components, while at higher temperature the products were composed of polycyclic aromatic hydrocarbons. With the high performance of the Hewlett-Packard 6890GC-5973MSD, more compounds were identified in comparison with previous studies.
- Piao, Mingjun,Chu, Shaogang,Zheng, Minghui,Xu, Xiaobai
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p. 1497 - 1512
(2007/10/03)
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- Preparation of highly functionalized Grignard reagents by an iodine-magnesium exchange reaction and its application in solid-phase synthesis
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At -40°C aryl iodides that contain other functional groups can be selectively converted into Grignard reagents, which react with electrophiles such as benzaldehyde in the usual manner [Eq. (a)]. Aryl bromides and iodides that are immobilized as esters on a Wang resin behave analogously.
- Boymond, Laure,Rottlaender, Mario,Cahiez, Gerard,Knochel, Paul
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p. 1701 - 1703
(2007/10/03)
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- Rapid Fluorous Stille Coupling Reactions Conducted under Microwave Irradiation
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Palladium-catalyzed fluorous Stille cross-coupling reactions with organic halides or triflates require only 90-120 s for completion when conducted under microwave irradiation. Comparable thermal reactions require about 1 day. Fourteen different coupling products were synthesized and isolated in good yields after three-phase extraction (FC-84, dichloromethane, water) and chromatography. The examples extend the scope of the fluorous Stille coupling with respect to both the tin and halide/triflate components. Applications in parallel synthesis are suggested.
- Larhed, Mats,Hoshino, Masahide,Hadida, Sabine,Curran, Dennis P.,Hallberg, Anders
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p. 5583 - 5587
(2007/10/03)
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- Novel process for the synthesis of 2-fluoro-1-olefins
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A process for preparing 2-fluoro-1-olefins or terminal bis-beta-fluoro-olefins which comprises reacting an appropriate allyl or alpha-olefinated starting material with phenylselenyl chloride and silver fluoride, and then reacting the intermediate phenylselenyl fluoride compound with ozone, and further reacting the resulting phenylselenoxide compound with an appropriate amine, to yield the desired fluorinated compounds.
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- Acyclic analogues of 2-(4-phenylpiperidino)cyclohexanol (vesamicol): Conformationally mobile inhibitors of vesicular acetylcholine transport
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Several 1,3-disubstituted propan-2-ols and one α,β-disubstituted ethanol (11i) were synthesized and evaluated as potential acyclic mimics of the vesicular acetylcholine transport inhibitor 2-(4-phenylpiperidinyl)cyclohexanol (1, vesamicol, AH5183). Analogues containing the 4-phenylpiperidyl fragment (11a, 11b) were more potent than those containing the 4-phenylpiperazyl moiety (11e, 11f). Substitution at the second terminal carbon of the propyl (or ethyl) fragment with simple lipophilic aryl substituents yielded potent inhibitors of vesicular acetylcholine storage, including (-)-11a and d-11i, which are equipotent with vesamicol. However, the activity of analogues containing bicyclic aryl groups was susceptible to aryl substitution patterns (11g vs 11h), indicating a definite receptor site topography. In addition, the inhibitory activity of these acyclic analogues was enantioselective, exhibiting a preference, similar to the parent vesamicol, for the levorotatory isomer [(-)-11a vs (+)-11a]. Therefore, the simple lipophilic acyclic vicinal amino alcohols may successfully mimic the biological activity of vesamicol.
- Efange,Michelson,Dutta,Parsons
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p. 2638 - 2643
(2007/10/02)
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- REACTIVITY OF SOME AROMATIC HYDROCARBONS DURING ALLYLATION
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The reactivity of biphenyl, diphenylmethane, 1,2-diphenylethane, cyclohexylbenzene, naphthalene, and α- and β-methylnaphthalenes during allylation with allyl alcohol in the presence of zinc chloride was investigated.It was found that the reactivity of the aromatic hydrocarbons varies in relation to structural factors.
- Magerramov, M. N.
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p. 305 - 307
(2007/10/02)
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