- Mixed Alkyl/Aryl Diphos Ligands for Iron-Catalyzed Negishi and Kumada Cross Coupling Towards the Synthesis of Diarylmethane
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Mixed alkyl/aryl diphos ligands have been prepared and their application in iron-catalyzed cross coupling of benzylic chlorides with diaryl zinc (Negishi) or aryl Grignard reagents (Kumada) towards the synthesis of diarylmethane has been evaluated. The iron?diphos catalytic system exhibited the enhanced activity and selectivity in the two coupling reactions. The electron-rich mixed PPh2/PCy2 ligands outperformed their symmetrical PPh2 congeners, and led to decreased homocoupling byproduct formation. It indicates that the electronic effect of the ligands plays an important role in the catalytic performance. The Fe catalyst supported by L8 bearing an electron-rich PCy2 substituent and a sterically demanding tert-butyl on ethene backbone exhibited the best catalytic performance and good functional group tolerance in the two cross coupling reactions.
- Ma, Xufeng,Wang, Han,Liu, Yao,Zhao, Xing,Zhang, Jun
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p. 5134 - 5140
(2021/11/16)
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- Preparation and application of blended nickel (II) complex with bisoxazoline derived azacyclo-carbene ligand and phosphite ester ligand
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The invention discloses a blended nickel (II) complex with a bisoxazoline derived azacyclo-carbene ligand and a phosphite ester ligand and application of the blended nickel (II) complex. The blended nickel (II) complex has a chemical formula of Ni(NHC)[P(OR)3]X2, in the formula, R is one of ethyl or isopropyl; X is one of bromine atoms or helium atoms; and NHC is the bisoxazoline derived azacyclo-carbene ligand. In the presence of magnesium chips, the blended nickel (II) complex with the bisoxazoline derived azacyclo-carbene ligand and the phosphite ester ligand, which is disclosed by the invention, is capable of catalyzing aromatic hydrocarbon or fluoro-aromatic hydrocarbon with low activity to have a reduction cross coupling reaction with a benzyl chloride type compound at a single temperature, then a diarylmethane compound can be generated at one step, and a novel method is provided for synthesizing diarylmethane compounds.
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Paragraph 0077-0078
(2019/10/17)
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- N-heterocyclic carbene–palladium complexes for Suzuki–Miyaura coupling reaction with benzyl chloride and aromatic boronic acid leading to diarylmethanes
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A family of N-heterocyclic carbene–palladium(II)–N,N-dimethylbenzylamine complexes ((NHC)LPdCl2; L?=?N,N-dimethylbenzylamine) were synthesized as well as characterized using single-crystal X-ray diffraction and spectroscopic data. These complexes exhibited higher catalytic activities for the Suzuki reaction of benzyl chlorides to afford diarylmethanes under milder conditions than other efficient (NHC)LPdCl2 complexes. Using the optimum conditions, the expected coupling products were obtained in moderate to high yields. All reactions were carried out in air and all starting materials were used as supplied without purification.
- Chen, Ming-Tsz,Wang, Wan-Rong,Li, Yi-Jun
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- Substrate switchable Suzuki-Miyaura coupling for benzyl ester: Vs. benzyl halide
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Two reaction conditions were developed to accomplish the substrate switchable Suzuki-Miyaura coupling of benzyl derivatives and arylboronic acid derivatives. Under conditions for esters, benzyl esters such as carbonates and acetates reacted with arylboronic acids to afford the corresponding diarylmethanes. However, the benzyl halides did not react under the same conditions. On the other hand, benzyl halides such as bromides and chlorides furnished diarylmethanes under conditions for halides, under which benzyl ester substrates did not react, in which water was found to play an important role. This switching system was tested using the intermolecular/intramolecular competitive reactions, during which the desired products could be synthesized by selecting the appropriate reaction conditions.
- Ohsumi, Masato,Ito, Akitaka,Nishiwaki, Nagatoshi
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p. 35056 - 35061
(2018/10/24)
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- Synthetic method of diarylmethanes
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The invention discloses a synthetic method of diarylmethanes. The method is characterized in that benzyl pseudohalide and aromatic boric acid are reacted in an organic solvent under alkaline condition. The method employs easily available raw materials, conversion is realized under effect of no transition metal catalysis, water-free and oxygen-free are not required, Lewis acid catalysis is not required, the method has wide substrate universality, and various substituted diarylmethanes can be synthesized by the method.
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Paragraph 0059; 0060; 0061; 0062; 0063
(2017/08/28)
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- Cooperative Al-H Bond Activation in DIBAL-H: Catalytic Generation of an Alumenium-Ion-Like Lewis Acid for Hydrodefluorinative Friedel-Crafts Alkylation
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The Ru-S bond in Ohki-Tatsumi complexes breaks oligomeric DIBAL-H structures into their more reactive monomer. That deaggregation is coupled to heterolytic Al-H bond activation at the Ru-S bond, formally splitting the Al-H linkage into hydride and an alumenium ion. The molecular structure of these Lewis pairs was established crystallographically, revealing an additional Ru-Al interaction next to the Ru-H and Al-S bonds. That bonding situation was further analyzed by quantum-chemical calculations and is best described as a three-center-two-electron (3c2e) donor-acceptor σ(Ru-H) → Al interaction. Despite the extra stabilization of the aluminum center by the interaction with both the sulfur atom and the Ru-H bond, the hydroalane adducts are found to be stronger Lewis acids and electrophiles than the free ruthenium catalyst and DIBAL-H in its different aggregation states. Hence, the DIBAL-H molecule and its Al-H bond are activated by the Ru-S bond, but these hydroalane adducts are not to be mistaken as sulfur-stabilized alumenium ions in a strict sense. The Ohki-Tatsumi complexes catalyze C(sp3)-F bond cleavage with DIBAL-H, and the catalytic setup is applied to hydrodefluorinative Friedel-Crafts alkylations. A broad range of CF3-substituted arenes is efficiently converted into unsymmetrical diarylmethanes with various arenes as nucleophiles. Computed fluoride-ion affinities (FIAs) of the hydroalane adducts as well as DIBAL-H in its aggregation states support this experimental finding.
- Forster, Francis,Mets?nen, Toni T.,Irran, Elisabeth,Hrobárik, Peter,Oestreich, Martin
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supporting information
p. 16334 - 16342
(2017/11/22)
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- Container Chemistry: Manipulating excited state behavior of organic guests within cavitands that form capsules in water
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Two new cavitands substituted with acid and alcohol groups (tetra-acid tetra-alcohol [TATA] and inverted TATA [iTATA]) bearing the same molecular skeleton as octa acid (OA) have been synthesized and their use as photochemical reaction containers explored. Isothermal calorimetric titration experiments suggest that the inclusion of organic molecules within these cavitands is driven both by favorable ΔH and ΔS and the substituents at the portals have little role to play. Comparison of the 2 new cavitands with the previous results on OA reveals that the presence of benzoate anion at the top periphery is essential for the cavitand to be a triplet sensitizer. Polarity within the water-soluble capsules, resulting from TATA and iTATA, was found to be close to that of ethylacetate and hydrocarbons, similar to that of OA. Photophysical studies with anthracene and camphorthione as guests disclose that the capsules made of 2 molecules of cavitands do not disassemble in the time scale of the excited states of the above guests (S1 in the case of anthracene and T1 in the case of camphorthione). Capsules ability to confine guests and the resulting photochemical intermediates has been tested by examining the photochemistry of 1-phenyl-3-para-tolyl-2-propanone. The radicals resulting from the Norrish type 1 cleavage of 1-phenyl-3-para-tolyl-2-propanone did not escape the cage and gave products, resulting from 100% cage effect. Availability of TATA and iTATA along with already reported similar cavitands expands the list of water-soluble capsule forming cavitands that could be used as molecular containers.
- Jagadesan, Pradeepkumar,Samanta, Shampa R.,Choudhury, Rajib,Ramamurthy, Vaidhyanathan
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- A Zwitterionic Palladium(II) Complex as a Precatalyst for Neat-Water-Mediated Cross-Coupling Reactions of Heteroaryl, Benzyl, and Aryl Acid Chlorides with Organoboron Reagents
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The Suzuki–Miyaura cross-coupling (SMC) reactions of several heteroaryl chlorides, benzyl chlorides, and aryl acid chlorides with (hetero)arylboron reagents have been investigated in the presence of [Pd(HL1)(PPh3)Cl2] (I) [HL1 = 3-[(2,6-diisopropylphenyl)-1-imidazolio]-2-quinoxalinide] as catalyst and K2CO3 as base in neat water. The synthesis of the heterocycle-containing biaryls required the addition of 2 mol-% of a phosphine ligand (PPh3 or X-Phos). A combination of more than 115 substrates were screened and it was found that I is a versatile catalyst that can produce heterocycle-containing biaryls, diarylmethanes, and benzophenones in moderate-to-excellent yields.
- Ramakrishna, Visannagari,Rani, Morla Jhansi,Reddy, Nareddula Dastagiri
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p. 7238 - 7255
(2018/01/01)
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- Coupling of arylboronic acids with benzyl halides or mesylates without adding transition metal catalysts
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We report herein a transition-metal-free coupling reaction of arylboronic acids with benzyl halides and mesylates for the construction of C(sp2)[sbnd]C(sp3) bonds. A unique feature of this coupling reaction is the formation regioisomers in some cases. Mechanistic studies suggest that this reaction may proceed via an unprecedented Friedel–Crafts-type reaction pathway under base conditions with the assistance of boronic acid moiety.
- Wu, Guojiao,Xu, Shuai,Deng, Yifan,Wu, Chaoqiang,Zhao, Xia,Ji, Wenzhi,Zhang, Yan,Wang, Jianbo
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p. 8022 - 8030
(2016/11/19)
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- Functional Ionic Liquids as Efficient and Recyclable Catalysts for the Methylation of Formaldehyde with Aromatics
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Abstract: Methylation of formaldehyde with various aromatics under functional ionic liquids catalysis has been developed. Among the ionic liquids investigated, triphenyl-(4-sulfobutyl)-phosphonium triflate ([TTPBs][CF3SO3]) showed high activity and afforded excellent yields of diarylmethane derivatives. A mechanism for the catalytic performance of [TTPBs][CF3SO3] is proposed. Besides, the catalyst can simply be separated from the reaction mixture by centrifugation and be recycled ten times without noticeable loss of activity. Graphical Abstract: Diarylmethane derivatives were successfully synthesized from the methylation of formaldehyde with aromatics using efficient and recyclable functional ionic liquids as catalysts, excellent yields and selectivities were obtained under solvent free conditions. The catalyst was reused at least ten consecutive recycles without noticeable loss in its catalytic activity. Meanwhile, the usability of catalyst was explored.[Figure not available: see fulltext.]
- Song, Heyuan,Jin, Fuxiang,Jin, Ronghua,Kang, Meirong,Li, Zhen,Chen, Jing
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p. 1264 - 1272
(2016/07/06)
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- Benzylation of arenes with benzyl halides synergistically promoted by in situ generated superacid boron trifluoride monohydrate and tetrahaloboric acid
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To examine the assembly methodology of diarylmethanes, a benzylation of (hetero)arenes with benzyl halides has been developed and various diarylmethanes were furnished with yields of up to 98% and regioselectivities of up to >99%. The complexation of the by-product halogen hydride with BF3·OEt2 generated the Bronsted acid BF3·HX (HBF3X, X=Cl or Br) in situ to synergistically promote the benzylation.
- Huang, Ruofeng,Zhang, Xiaohui,Pan, Jing,Li, Jiaqiang,Shen, Hang,Ling, Xuege,Xiong, Yan
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supporting information
p. 1540 - 1546
(2015/03/04)
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- Multimetallic Ir-Sn3-catalyzed substitution reaction of π-activated alcohols with carbon and heteroatom nucleophiles
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An atom economic and catalytic substitution reaction of π-activated alcohols by a multimetallic IreSn3 complex has been demonstrated. The multimetallic IreSn3 complex can be easily synthesized from the reaction between [Cp*IrCl2]2 and SnCl2. In presence of as little as 1 mol % of the catalyst three different types of π-activated alcohols, namely benzyl, allyl, and propargyl alcohols, have been successfully transformed into alkylated products using carbon (arenes, heteroarenes, allyltrimethylsilane, and 1,3-dicarbonyls), nitrogen (sulfonamides), oxygen (alcohols), and sulfur (thiols) nucleophiles in very high yields. An electrophilic mechanism is proposed from the Hammett correlation study.
- Maity, Arnab Kumar,Chatterjee, Paresh Nath,Roy, Sujit
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p. 942 - 956
(2013/07/25)
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- Palladium-catalyzed desulfitative cross-coupling reaction of sodium sulfinates with benzyl chlorides
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A palladium-catalyzed approach for the synthesis of diarylmethanes from sodium sulfinates and benzyl chlorides is described. Various aromatic sodium sulfinates were used as aryl sources via extrusion of SO2 and gave the diarylmethanes in moderate to good yields.
- Zhao, Feng,Tan, Qi,Xiao, Fuhong,Zhang, Shufeng,Deng, Guo-Jun
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supporting information
p. 1520 - 1523
(2013/06/26)
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- Exploiting boron-zinc transmetallation for the arylation of benzyl halides: What are the reactive species?
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One step Beyond: The transmetallation reactions of ArB(OH)2 and Ar3B3O3 with Et2Zn are far more complicated than previously supposed, with solvent-dependent equilibria between ArB(OY)2 at one side and [RZn(solv)3][BR4] at the other (see picture). While the role of the highly reactive organozinc cation has not been implicated before, its importance for the activation of an otherwise sluggish class of electrophiles is shown. Copyright
- Bedford, Robin B.,Gower, Nicholas J.,Haddow, Mairi F.,Harvey, Jeremy N.,Nunn, Joshua,Okopie, Rukeme A.,Sankey, Rosalind F.
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supporting information; experimental part
p. 5435 - 5438
(2012/07/03)
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- Influence of lewis acid and solvent in the hydrosiylation of aldehydes and ketones with Et3SiH; Tris(pentafluorophenyl)borane B(C 6F5)3 versus Metal inflates [M(OTf) 3; M = Sc, Bi, Ga, and Al] - Mecha
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The scope of the B(C6F5)3-catalyzed hydrosilylation of (X)Ph- CH=O and (X)Ph-C(R)=O was expanded to include a large set of subslitulents (X =H, p-Me, o-Me, p-F, o-F, p-Cl, p-Br, p-NO2m, m-NO2, p-Et; R
- Bach, Peter,Albright, Andrea,Laali, Kenneth K.
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experimental part
p. 1961 - 1966
(2009/09/06)
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- Chlorine borrowing: An efficient method for an easier use of alcohols as alkylation agents
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Chlorine functionalised tin dioxide nanoparticles proved able to partially convert alcohols into the corresponding chlorides, which act as alkylation agents with an increased electrophilicity, as evidenced on ether formation and Friedel-Crafts reactions.
- Makowski, Philippe,Rothe, Regina,Thomas, Arne,Niederberger, Markus,Goettmann, Frederic
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scheme or table
p. 34 - 37
(2010/04/22)
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- Cooperative Friedel-Crafts catalysis in heterobimetallic regime: Alkylation of aromatics by π-activated alcohols
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The highly active Friedel-Crafts alkylation (FCA) catalyst, [Ir(COD)Cl(SnCl3)(SnCl4)(arene)]+Cl- (1-SnCl4), is easily generated in one-pot from [Ir(COD)Cl]2 or [Ir(COD)(μ-Cl)Cl(SnCl3)]2 (1) and SnCl4. The reaction of arenes, heteroarenes with benzyl, and allyl alcohols is promoted by 1-SnCl4 (1 mol %) with high turnover frequency. Kinetic evidence is presented to establish FCA pattern. From dual-catalyst combination studies varying the transition metal and main group metal partner, the efficiency of the present catalysts is attributed to the electrophilic "IrIII-SnIV" core. Copyright
- Choudhury, Joyanta,Podder, Susmita,Roy, Sujit
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p. 6162 - 6163
(2007/10/03)
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- Synthesis and structural characterization of complexes derived from treatment of gallium trichloride with 3,5-diphenylpyrazole
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The adduct GaCl3(Ph2pzH) (Ph2pzH, 3,5-diphenylpyrazole) was synthesized in 96% yield upon treatment of equimolar amounts of gallium trichloride with Ph2pzH in toluene at room temperature. The tetrachlorogallate
- Yu, Zhengkun,Korolev, Andrey V.,Heeg, Mary Jane,Winter, Charles H.
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p. 1117 - 1123
(2008/10/08)
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- A Study of N-Nitrosoamide-Mediated Friedel-Crafts Type Benzylation of Benzene-Toluene and Benzene-Anisole1a
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Nitrogen-separated carbocation-carboxylate ion pairs were employed as sources of carbocations in the alkylation of aromatic compounds. The N-nitrosoamide approach to these nitrogenous-molecule-separated ion pairs is an excellent alternative to the standard acid-catalyzed Friedel-Crafts approach for studies of the alkylation because of the following variables: high reactivity of the electrophile, stability of the products, strict kinetic control, homogeneity, lack of over alkylation, straightforward chemistry, and good product balance. In deaminative benzylations of benzene-toluene and anisole-benzene mixtures, the values of kX/kB and % meta isomer are significantly different from those observed in the standard benzylations in a manner that indicates the deaminative electrophiles are more reactive than those generated by the standard Friedel-Crafts approach. The reactions show a direct proportionality between inter- and intramolecular selectivities and thus follow the Brown selectivity relationship (BSR). The benzylation of 2,4,6-trideuteriotoluene provided no evidence for deuterium rearrangements (or coupled benzyl rearrangements) in the arenium ion intermediate. Kinetic isotope effects were not detected. The methyl substituent on toluene appears to affect intermolecular selectivity (kT/kB) and intramolecular selectivity (o, m, p distribution) to similar degrees. A mechanism is proposed in which both selectivities are determined by activation energy differences in the transition states leading to the σ-complex intermediates. The observation that most standard Friedel-Crafts benzylations do not follow the BSR is discussed in terms of possible systematic errors in those cases. Silver ion-assisted Friedel-Crafts benzylations were performed under dry, basic conditions to investigate whether the standard approach could lead to data that obey the BSR.
- Darbeau, Ron W.,White, Emil H.
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p. 1121 - 1131
(2007/10/03)
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- A Study of Essentially Free Carbocations Derived via Diazonium and Oxo Diazonium Ions in the Liquid Phase
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Nitrogen- and nitrous oxide-separated ion pairs containing 4-substituted benzyl cations and carboxylate or tosylate anions were prepared by thermolysis of N-nitroso- and N-nitroamides, acidification of phenyldiazomethane, and nitrosation of N-benzyl-O-benzoylhydroxylamine. The cations were generated in benzene/toluene and benzene/anisole mixtures and were found to partition between the counterion and the solvent and between the aromatic cosolvent and benzene. A familial relationship among the methods was observed. As the cation became more reactive, the yield of solvent-derived products (SDPs) rose and the ratio of rate constants for its reaction with toluene versus benzene, kT/kB, fell. The yield of SDP also rose as the temperature was decreased and as N2 was replaced by N2O; however, kT/kB remained unchanged. Inert diluents had no effect on kT/kB but decreased hydrocarbon yield by 40% on 2-fold dilution. In the presence of reactive diluents that are converted into secondary alkylating agents, both the % hydrocarbon and kT/kB rose. These results are interpreted in terms of the intermediacy of inert-molecule-separated ion pairs (IMSIPs) in deamination. The cation reacted with benzoates and tosylates not only at the oxygens but also at the ipso carbon; subsequent decarboxylation and desulfonylation, respectively, led to diphenylmethanes. The ester/SDP ratio is introduced as a new measure of carbocation reactivity.
- Darbeau, Ron W.,White, Emu H.,Song, Fenhong,Darbeau, Nyla R.,Chou, James
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p. 5966 - 5978
(2007/10/03)
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- Structural requirements for decarbonylative α,α-diarylation reaction of 2-methoxyalkanoic acids in phosphorus pentoxide-methanesulfonic acid mixture yielding 1,1-diarylalkane homologs
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2-Methoxyalkanoic acids were found to undergo consecutive decarbonylative α,α-diarylation in P2O5-MsOH instead of Friedel-Crafts type arylation on the carbonyl carbon. The influence of the substituents of the arenes and the carboxylic acids in this reaction was elucidated based on the reaction yields. The reaction behavior was found to be primarily governed by the electron-withdrawing/releasing property of the α-substituents on the carboxylic acids as well as the positive species-accepting ability of the arenes. The steric hindrance was shown to participate in determining the reaction feasibility as a secondary factor.
- Yonezawa, Noriyuki,Hino, Tetsuo,Tokita, Yoshimi,Matsuda, Kazuhisa,Ikeda, Tomiki
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p. 14287 - 14296
(2007/10/03)
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- Superacid-Catalyzed Reductive Friedel-Crafts Reaction of Arenes Using Arenecarbaldehyde Acetals
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Reaction of 2-aryl-1,3-dioxane with arenes in the presence of a catalytic amount of trifluoromethane-sulfonic acid gave the corresponding diarylmethanes in good to excellent yields. The acid-catalyzed Friedel-Crafts benzylation of arenes could altenatively be carried out using arenecarbaldehyde and 1,3-propanediol. The reaction was assumed to proceed through a redox process involving hydride shift from the cyclic acetal moiety to the benzylic carbon. The hydride shift was confirmed by the reaction with 5-ethyl-2-phenyl-4,4,6,6-tetradeuterio-1,3-dioxane, wherein more than 90% deuterium was incorporated into the benzylic carbon of the diphenylmethane. Diphenylmethyl ether Ph2CHOCH2CH2CH2OH also reacted with benzene to afford diphenylmethane under the same reaction conditions, suggesting that the ether should be the plausible intermediate that underwent the hydride shift.
- Fukuzawa, Shin-Ichi,Tsuchimoto, Teruhisa,Hiyama, Tamejiro
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p. 151 - 156
(2007/10/03)
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- Scandium(III) Triflate-Catalyzed Friedel-Crafts Alkylation Reactions
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The Sc(OTf)3-catalyzed Friedel-Crafts alkylation reaction with an alcohol, an arenecarbaldehyde or an arenecarbaldehyde acetal as the alkylating agent affords a diarylmethane or an allylbenzene derivative highly selectively. The salient feature of this reaction is that only a catalytic amount of Sc(OTf)3 can effect the reaction. Furthermore, Sc(OTf)3 is recoverable and reusable after the synthetic reaction. The Sc(OTf)3-catalyzed benzylation using an arenecarbaldehyde and 1,3-propanediol or their acetal affords diarylmethane as a sole product in excellent yields in sharp contrast to the original Friedel-Crafts reaction. Since no reaction occurs in the absence of 1,3-propanediol, the reaction is considered to proceed through a redox process including a hydride shift. The hydride shift mechanism is strongly supported by the experimental evidence. The reaction of benzaldehyde with benzene in the presence of 1,3-propanediol-1,1,3,3,-d4 gives rise to the deuterium incorporation into the benzylic carbon of diphenylmethane. Worthy of note is that 1,3-propanediol acts as the hydride source. Herein, diphenylmethyl 3-hydroxypropyl ether is assumed to be the most likely intermediate. In this reaction, Sc(OTf)3 catalyst effectively promotes initial acetal formation, electrophilic aromatic substitution, and successive intramolecular hydride transfer.
- Tsuchimoto, Teruhisa,Tobita, Kazuo,Hiyama, Tamejiro,Fukuzawa, Shin-Ichi
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p. 6997 - 7005
(2007/10/03)
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- Scandium(III) trifluoromethanesulfonate-catalysed reductive Friedel-Crafts benzylation of aromatic compounds using arenecarbaldehydes and propane-1,3-diol
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Scandium(III) trifluoromethanesulfonate catalyses the Friedel-Crafts benzylation of aromatic compounds with arenecarbaldehydes and propane-1,3-diol to produce, through a clean redox process, diarylmethanes in high to excellent yields.
- Tsuchimoto, Teruhisa,Hiyama, Tamejiro,Fukuzawa, Shin-Ichi
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p. 2345 - 2346
(2007/10/03)
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- C,O-dilithiated diarylmethanols: Easy and improved preparation by naphthalene-catalysed lithiation of diaryl ketones and reactivity toward electrophiles
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The lithiation of different diaryl ketones 1 with an excess of lithium powder and a catalytic amount (8 mol %) of naphthalene in tetradrofuran at -30°C leads to the formation of the corresponding dianions of the type I, with Met=Li, which react with several electrophiles (E+=MeI, EtBr, Pr(i)CHO, PhCHO, cyclohexanone, MeCN) to give, after hydrolysis, the expected substituted diarylmethanols 2.
- Guijarro,Mancheno,Yus
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p. 1327 - 1334
(2007/10/02)
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- Acylation du methyl-1 cyclohexene par chlorures d'acide benzoique catalysee par CF3SO3H et resolution chromatographique sur triacetylcellulose des chloro-9 methyl-4a tetrahydro-2,3,4,4a 1H-fluorenes obtenus
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Acetylation of 1-methylcyclohexene with substituted aromatic acyl halides in the presence of CF3SO3H gives diphenylmethane derivatives 3 and 9-chloro-4a-methyl tetrahydro-1H-fluorenes 4.Compounds 4 are separated into enantiomers by liquid chromatography o
- Roussel, Christian,Shaimi, Latifa,Chemlal, Ahmed
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p. 688 - 693
(2007/10/02)
-
- ARYLALKYLATION OF 4-tert-BUTYLTOLUENE WITH SUBSTITUTED BENZYL CHLORIDES
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The reaction of 4-alkylbenzyl chlorides with 4-tert-butyltoluene in the presence of titanium tetrachloride and ferric chloride leads to the formation of 2-methyl-4'-alkyl-5-tert-butyldiphenylmethanes.The arylalkylation of 4-tert-butyltoluene with 2- and 4-chlorobenzyl chlorides, catalyzed by titanium tetrachloride, leads to the formation of mixtures of 2-methyl-5-tert-butyldiphenylmethane, 2-tert-butyl-5-methyldiphenylmethane, and isomeric methyldiphenylmethanes containing a chloride atom in the benzyl fragment.The products of the reaction catalyzed by ferric chloride do not contain 2-tert-butyl-5-methylchlorodiphenylmethanes.The reacti on of 4-nitrobenzyl chloride with 4-tert-butyltoluene in the presence of ferric chloride leads to the formation of a mixture of 2-methyl-4'-nitro-5-tert-butyldiphenylmethane and isomeric methylnitrodiphenylmethanes.Under the influence of AlCl3-CH3NO2 in benzene 2,4'-dimethyl-5-tert-butyldiphenylmethane eliminates both the 4-methylbenzyl group and the tert-butyl group.Under analogous conditions 2-methyl-5-tert-butyldiphenylmethanes containing a chlorine atom or a nitro group in the benzyl fragment are dealkylated with the elimination of only the tert-butyl group.
- Pozdnyakovich, Yu. V.,Savyak, R. P.,Shein, S. M.
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p. 522 - 526
(2007/10/02)
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- Reduction of carbonyl compounds promoted by silicon hydrides under the influence of trimethylsilyl-based reagents
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The synthetic utility of hydrosilanes under the influence of trimethylsilyl-based reagents as new reducing systems is described. 1,1,3,3-Tetramethyldisiloxane (TMDS) reagent in combination with iodotrimethylsilane or bromotrimethylsilane produces alkyl halides from aldehydes in good to excellent yields.Polymethylhydrosiloxane (PMS) in the presence of iodotrimethylsilane also produces benzyl iodides in excellent yields.On the contrary, PMS reagent was found unsuitable for the synthesis of benzyl bromides.Similary, TMDS reagent in combination with trimethylsilyl triflate produces symmetrical ethers from aldehydes without concomitant formation of competitive products.Under similar conditions, PMS reagent failed to provide the expected symmetrical ethers and Friedel-Crafts products were formed.Reduction of quinones to hydroquinones is also described.
- Aizpurua, Jesus M.,Lecea, Begona,Palomo, Claudio
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p. 2342 - 2347
(2007/10/02)
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- Sonochemical Switching of Reaction Pathways in Solid-Liquid Two-phase Reactions
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Ultrasonic irradiation of a mixture of benzyl bromide, potassium cyanide, and alumina in an aromatic solvent yields benzyl cyanide, whereas mechanical agitation gives the Friedel-Crafts type product; sonication changes the main reaction pathway from aromatic electrophilic to aliphatic nucleophilic substitution.
- Ando, Takashi,Sumi, Shinjiro,Kawate, Takehiko,Ichihara, Junko,Hanafusa, Terukiyo
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p. 439 - 440
(2007/10/02)
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- PREPARATION OF SOME TRIMETHYL- AND METHYLETHYLBIPHENYLS AND REACTIVITY OF AROMATIC HYDROCARBONS IN THE GOMBERG REACTION
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Trimethyl- and methylethylbiphenyls with the alkyl groups in the both phenyl rings have been prepared by the Gomberg reaction and identified by the capillary gas-liquid chromatography.Depending on choice of the aromatic hydrocarbon either individual isomers or their mixtures (three at the most) have been obtained which were contaminated with compounds of diarylmethane type in many cases.The methylethylbiphenyls have only been prepared as mixtures contaminated with diarylmethanes.These side products have been prepared by independent syntheses.A method has been developed for isolation and separation of mixtures of trimethyl- and methylethylbiphenyls from the reaction products containing tarry products.The method is suitable for preparation of small amounts of some analytical standards.The HMO method has been used for calculation of values of the radical superdelocalizabilities at individual centres in the molecules of o-, m- and p-xylene, toluene and ethylbenzene, and these values have been compared with composition of the Gomberg reaction products from these hydrocarbons.The competitive technique has been used for comparison of the reactivities of the mentioned aromatic substrates in the Gomberg reactions.
- Novrocik, Jan,Novrocikova, Marta,Titz, Milos
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p. 3140 - 3149
(2007/10/02)
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