- A General Concurrent Template Strategy for Ordered Mesoporous Intermetallic Nanoparticles with Controllable Catalytic Performance
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We report a general concurrent template strategy for precise synthesis of mesoporous Pt-/Pd-based intermetallic nanoparticles with desired morphology and ordered mesostructure. The concurrent template not only supplies a mesoporous metal seed for re-crystallization growth of atomically ordered intermetallic phases with unique atomic stoichiometry but also provides a nanoconfinement environment for nanocasting synthesis of mesoporous nanoparticles with ordered mesostructure and rhombic dodecahedral morphology under elevated temperature. Using the selective hydrogenation of 3-nitrophenylacetylene as a proof-of-concept catalytic reaction, mesoporous intermetallic PtSn nanoparticles exhibited remarkably controllable intermetallic phase-dependent catalytic selectivity and excellent catalytic stability. This work provides a very powerful strategy for precise preparation of ordered mesoporous intermetallic nanocrystals for application in selective catalysis and fuel cell electrocatalysis.
- Ariga, Katsuhiko,Liu, Ben,Lv, Hao,Qin, Huaiyu,Yamauchi, Yusuke
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supporting information
(2022/03/08)
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- A Magnetically Separable Pd Single-Atom Catalyst for Efficient Selective Hydrogenation of Phenylacetylene
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Selective hydrogenation of alkynes to alkenes plays a crucial role in the synthesis of fine chemicals. However, how to achieve high selectivity and effective separation of the catalyst and substrate while obtaining high activity is the key for this reaction. In this work, a Pd single-atom catalyst is anchored to the shell of magnetic core–shell particles that consist of a Ni-nanoparticles core and a graphene sheets shell (Ni@G) for semi-hydrogenation of phenylacetylene, delivering 93% selectivity to styrene at full conversion with a robust turnover frequency of 7074 h?1 under mild reaction conditions (303 K, 2?bar H2). Moreover, the catalyst can be recovered promptly from the liquid phase due to its magnetic separability, which makes it present good stability for enduring five cycles. Experimental and theoretical investigations reveal that H2 and substrates are activated by atomically dispersed Pd atoms and Ni@G hybrid support, respectively. The hydrogenation reaction occurs on the surface of Ni@G via hydrogen spillover from the metal to the support. Such a strategy opens an avenue for designing highly active, selective, and magnetically recyclable catalysts for selective hydrogenation in liquid reaction systems.
- Zhao, Linmin,Qin, Xuetao,Zhang, Xirui,Cai, Xiangbin,Huang, Fei,Jia, Zhimin,Diao, Jiangyong,Xiao, Dequan,Jiang, Zheng,Lu, Ruifeng,Wang, Ning,Liu, Hongyang,Ma, Ding
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- Development of LM98, a Small-Molecule TEAD Inhibitor Derived from Flufenamic Acid
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The YAP-TEAD transcriptional complex is responsible for the expression of genes that regulate cancer cell growth and proliferation. Dysregulation of the Hippo pathway due to overexpression of TEAD has been reported in a wide range of cancers. Inhibition of TEAD represses the expression of associated genes, demonstrating the value of this transcription factor for the development of novel anti-cancer therapies. We report herein the design, synthesis and biological evaluation of LM98, a flufenamic acid analogue. LM98 shows strong affinity to TEAD, inhibits its autopalmitoylation and reduces the YAP-TEAD transcriptional activity. Binding of LM98 to TEAD was supported by 19F-NMR studies while co-crystallization experiments confirmed that LM98 is anchored within the palmitic acid pocket of TEAD. LM98 reduces the expression of CTGF and Cyr61, inhibits MDA-MB-231 breast cancer cell migration and arrests cell cycling in the S phase during cell division.
- Mélin, Léa,Abdullayev, Shuay,Fnaiche, Ahmed,Vu, Victoria,González Suárez, Narjara,Zeng, Hong,Szewczyk, Magdalena M.,Li, Fengling,Senisterra, Guillermo,Allali-Hassani, Abdellah,Chau, Irene,Dong, Aiping,Woo, Simon,Annabi, Borhane,Halabelian, Levon,LaPlante, Steven R.,Vedadi, Masoud,Barsyte-Lovejoy, Dalia,Santhakumar, Vijayaratnam,Gagnon, Alexandre
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p. 2982 - 3002
(2021/08/03)
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- Selective and Additive-Free Hydrogenation of Nitroarenes Mediated by a DMSO-Tagged Molecular Cobalt Corrole Catalyst
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We report on the first cobalt corrole that effectively mediates the homogeneous hydrogenation of structurally diverse nitroarenes to afford the corresponding amines. The given catalyst is easily assembled prior to use from 4-tert-butylbenzaldehyde and pyrrole followed by metalation of the resulting corrole macrocycle with cobalt(II) acetate. The thus-prepared complex is self-contained in that the hydrogenation protocol is free from the requirement for adding any auxiliary reagent to elicit the catalytic activity of the applied metal complex. Moreover, a containment system is not required for the assembly of the hydrogenation reaction set-up as both the autoclave and the reaction vessels are readily charged under a regular laboratory atmosphere.
- Sch?fberger, Wolfgang,Timelthaler, Daniel,Topf, Christoph
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supporting information
p. 2114 - 2120
(2021/07/22)
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- Exploring the nitro group reduction in low-solubility oligo-phenylenevinylene systems: Rapid synthesis of amino derivatives
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A small series of amino oligo-phenylenevinylenes (OPVs) were successfully synthesized from their nitro-analogs in a rapid, simple, and highly efficient fashion employing a sodium sulfide/pyridine system as a reducing agent. In this research, classic and sustainable reduction methodologies including NH4HCO2/Zn and a choline chloride/tin (II) chloride deep eutectic solvent (DES) were also evaluated, showing degradation products, incomplete reactivity, and product isolation difficulties in all cases. The straightforward Na2S/pyridine synthetic protocol proved to maintain the E-E stereochemistry of the OPV backbone that has been previously assembled by the Mizoroki–Heck cross-coupling reaction. Also, the optoelectronic properties were determined and discussed, considering the amino group insertion in these conjugated systems as a contribution for future construction of novel materials with applications in supramolecular electronics, light harvesting, and photocatalysis.
- Acelas, Mauricio,Sierra, Andrés Felipe,Sierra, César A.
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supporting information
p. 1335 - 1352
(2020/03/04)
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- Iron-Catalyzed Direct Julia-Type Olefination of Alcohols
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Herein, we report an iron-catalyzed, convenient, and expedient strategy for the synthesis of styrene and naphthalene derivatives with the liberation of dihydrogen. The use of a catalyst derived from an earth-abundant metal provides a sustainable strategy to olefins. This method exhibits wide substrate scope (primary and secondary alcohols) functional group tolerance (amino, nitro, halo, alkoxy, thiomethoxy, and S- A nd N-heterocyclic compounds) that can be scaled up. The unprecedented synthesis of 1-methyl naphthalenes proceeds via tandem methenylation/double dehydrogenation. Mechanistic study shows that the cleavage of the C-H bond of alcohol is the rate-determining step.
- Landge, Vinod G.,Babu, Reshma,Yadav, Vinita,Subaramanian, Murugan,Gupta, Virendrakumar,Balaraman, Ekambaram
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p. 9876 - 9886
(2020/09/03)
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- Tetrahydropyrrole compound, preparation method, pharmaceutical composition and application thereof
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The invention discloses a tetrahydropyrrole compound and a preparation method, a pharmaceutical composition and application thereof. The tetrahydropyrrole compound of the invention is as shown in thegeneral formula (I). The tetrahydropyrrole compound of the invention has an excellent inhibitory effect on the positive symptom of schizophrenia, and has equivalent or stronger efficacy in comparisonwith the positive medicine olanzapine. In addition, the compound of the invention has a dual inhibitory effect on a D2 receptor and a DAT receptor, can effectively treat schizophrenia and improve negative symptoms and cognitive functions, and helps reduce side-effect of centrum and secretion of lactogen.
- -
-
Paragraph 0408-0413
(2019/07/16)
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- Hydroxyl Assisted Rhodium Catalyst Supported on Goethite Nanoflower for Chemoselective Catalytic Transfer Hydrogenation of Fully Converted Nitrostyrenes
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Control of chemoselectivity is a special challenge for the reduction of nitroarenes bearing one or more unsaturated groups. Here, we report a flower-like Rh/α-FeOOH catalyst for the chemoselective hydrogenation of nitrostyrene to vinylaniline over full conversion, which benefits the new functionalized aminostyrene because the multisubstituted aminostyrenes are usually commercially unavailable. This catalyst does not only show desirable selectivity for the vinylanilines, but also exhibits the inertness to various other reducible groups over wide reaction duration. The catalytic selectivity for the reduction of the nitro group towards vinyl group was investigated by the control experiments and FT-IR analysis. We have found that the abundant hydroxyl groups in the α-FeOOH may contribute to the improvement of catalytic activity and selectivity. Furthermore, the catalyst exhibits excellent stability and keeps its catalytic performance even after 6 cycles. (Figure presented.).
- Hu, Zenan,Ai, Yongjian,Liu, Lei,Zhou, Junjie,Zhang, Gang,Liu, Hongqi,Liu, Xiangyu,Liu, Zhibo,Hu, Jianshe,Sun, Hong-bin,Liang, Qionglin
-
supporting information
p. 3146 - 3154
(2019/05/10)
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- Copper-Catalyzed Oxidative Difunctionalization of Terminal Unactivated Alkenes
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The copper(II)-promoted free-radical oxidative difunctionalization of terminal alkenes to access ketoazides by utilizing molecular oxygen has been reported. A series of styrene derivatives have been evaluated and were found to be compatible to give the desired difunctionalized products in moderate to good yields. The role of molecular oxygen both as an oxidant and oxygen atom source in this catalytic transformation has been unquestionably demonstrated by 18O-labeling studies and a radical mechanistic pathway involving the oxidative formation of azidyl radicals is also designed. This environment-friendly catalytic oxidative protocol can transform aldehyde to nitrile.
- Hussain, Muhammad Ijaz,Feng, Yangyang,Hu, Liangzhen,Deng, Qingfu,Zhang, Xiaohui,Xiong, Yan
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p. 7852 - 7859
(2018/05/30)
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- Enantioselective, Catalytic Vicinal Difluorination of Alkenes
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The enantioselective, catalytic vicinal difluorination of alkenes is reported by II/IIII catalysis using a novel, C2-symmetric resorcinol derivative. Catalyst turnover via in situ generation of an ArIIIIF2 species is enabled by Selectfluor oxidation and addition of an inexpensive HF–amine complex. The HF:amine ratio employed in this process provides a handle for regioselective orthogonality as a function of Br?nsted acidity. Selectivity reversal from the 1,1-difluorination pathway (geminal) to the desired 1,2-difluorination (vicinal) is disclosed (>20:1 in both directions). Validation with electron deficient styrenes facilitates generation of chiral bioisosteres of the venerable CF3 unit that is pervasive in drug discovery (20 examples, up to 94:06 e.r.). An achiral variant of the reaction is also presented using p-TolI (up to >95 % yield).
- Scheidt, Felix,Sch?fer, Michael,Sarie, Jér?me C.,Daniliuc, Constantin G.,Molloy, John J.,Gilmour, Ryan
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supporting information
p. 16431 - 16435
(2018/11/23)
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- Catalytic Geminal Difluorination of Styrenes for the Construction of Fluorine-rich Bioisosteres
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A geminal difluorination of alkenes based on I(I)/I(III) catalysis is disclosed, which is compatible with a range of electronically and substitutionally diverse styrenes (27 examples, up to 89% yield). Employing inexpensive p-TolI as the organocatalyst, turnover is enabled by Selectfluor-mediated oxidation to generate the ArIF2 species in situ. Extension to include α-substituted styrenes bearing fluorine-containing groups is disclosed and provides an expansive platform for the generation of fluorine-rich architectures.
- Scheidt, Felix,Neufeld, Jessica,Sch?fer, Michael,Thiehoff, Christian,Gilmour, Ryan
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supporting information
p. 8073 - 8076
(2019/01/04)
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- Terminal Alkenes from Acrylic Acid Derivatives via Non-Oxidative Enzymatic Decarboxylation by Ferulic Acid Decarboxylases
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Fungal ferulic acid decarboxylases (FDCs) belong to the UbiD-family of enzymes and catalyse the reversible (de)carboxylation of cinnamic acid derivatives through the use of a prenylated flavin cofactor. The latter is synthesised by the flavin prenyltransferase UbiX. Herein, we demonstrate the applicability of FDC/UbiX expressing cells for both isolated enzyme and whole-cell biocatalysis. FDCs exhibit high activity with total turnover numbers (TTN) of up to 55000 and turnover frequency (TOF) of up to 370 min?1. Co-solvent compatibility studies revealed FDC's tolerance to some organic solvents up 20 % v/v. Using the in-vitro (de)carboxylase activity of holo-FDC as well as whole-cell biocatalysts, we performed a substrate profiling study of three FDCs, providing insights into structural determinants of activity. FDCs display broad substrate tolerance towards a wide range of acrylic acid derivatives bearing (hetero)cyclic or olefinic substituents at C3 affording conversions of up to >99 %. The synthetic utility of FDCs was demonstrated by a preparative-scale decarboxylation.
- Aleku, Godwin A.,Prause, Christoph,Bradshaw-Allen, Ruth T.,Plasch, Katharina,Glueck, Silvia M.,Bailey, Samuel S.,Payne, Karl A. P.,Parker, David A.,Faber, Kurt,Leys, David
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p. 3736 - 3745
(2018/08/03)
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- Gold(i)-catalyzed cross-coupling reactions of aryldiazonium salts with organostannanes
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Gold(i)-catalyzed cross-coupling reactions of aryldiazonium salts with organostannanes are described. This redox neutral strategy offers an efficient approach to diverse biaryls, vinyl arenes and arylacetylenes. Monitoring the reaction with NMR and ESI-MS provided strong evidence for the in situ formation of Ph3PAuIR (R = aryl, vinyl and alkynyl) species which is crucial for the activation of aryldiazonium salts.
- Akram, Manjur O.,Shinde, Popat S.,Chintawar, Chetan C.,Patil, Nitin T.
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supporting information
p. 2865 - 2869
(2018/05/03)
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- Pd-Catalyzed Vinylation of Aryl Halides with Inexpensive Organosilicon Reagents Under Mild Conditions
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Pd-catalyzed Hiyama vinylation reaction of non-activated aryl chlorides and bromides under mild conditions was developed. The use of efficient vinyl donors and electron-rich sterically hindered phosphine ligands was critical for the success of the reaction. The products of this transformation can be used for Am/Cm separation, an important challenge in nuclear fuel reprocessing. The substituent effect on Am/Cm separating selectivity was also achieved, which could contribute to the development of new chromatographic materials for the separation of Am and Cm.
- Yang, Chu-Ting,Han, Jun,Liu, Jun,Li, Yi,Zhang, Fan,Yu, Hai-Zhu,Hu, Sheng,Wang, Xiaolin
-
supporting information
p. 10324 - 10328
(2018/07/31)
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- Efficient synthesis of functionalized olefins by Wittig reaction using Amberlite resin as a mild base
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A convenient procedure for the synthesis of olefins by the reaction of stabilized, semistabilized, and nonstabilized phosphorous ylides with various aldehydes or ketone using Amberlite resin as a mild base is described. Our developed method offers facile and racemization-free synthesis of α,β-unsaturated amino esters and chiral allylic amine. The developed methodology offers mild reaction conditions, high efficiency, and facile isolation of the final products, a practical alternative to known procedures.
- Valkute, Tushar R.,Aratikatla, Eswar K.,Bhattacharya, Asish K.
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p. 581 - 589
(2017/03/15)
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- SQUALENE COMPOUNDS AS MODULATORS OF LDL-RECEPTOR EXPRESSION
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The present invention relates to compounds that modify low density lipoprotein receptor (LDLR) expression. The compounds have the structural formula I shown below: wherein m, R1, n, R2 and R3 are each as defined herein. The present invention also relates to processes for the preparation of these compounds, to pharmaceutical compositions comprising them, and to their use in the treatment of diseases or disorders associated with elevated levels of low density lipoprotein cholesterol (LDL-C).
- -
-
Paragraph 0005; 0023
(2016/04/20)
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- Mechanism of the Novel Prenylated Flavin-Containing Enzyme Ferulic Acid Decarboxylase Probed by Isotope Effects and Linear Free-Energy Relationships
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Ferulic acid decarboxylase from Saccharomyces cerevisiae catalyzes the decarboxylation of phenylacrylic acid to form styrene using a newly described prenylated flavin mononucleotide cofactor. A mechanism has been proposed, involving an unprecedented 1,3-dipolar cyclo-addition of the prenylated flavin with the α=β bond of the substrate that serves to activate the substrate toward decarboxylation. We measured a combination of secondary deuterium kinetic isotope effects (KIEs) at the α- and β-positions of phenylacrylic acid together with solvent deuterium KIEs. The solvent KIE is 3.3 on Vmax/KM but is close to unity on Vmax, indicating that proton transfer to the product occurs before the rate-determining step. The secondary KIEs are normal at both the α- and β-positions but vary in magnitude depending on whether the reaction is performed in H2O or D2O. In D2O, the enzyme catalyzed the exchange of deuterium into styrene; this reaction was dependent on the presence of bicarbonate. This observation implies that CO2 release must occur after protonation of the product. Further information was obtained from a linear free-energy analysis of the reaction through the use of a range of para- and meta-substituted phenylacrylic acids. Log(kcat/KM) for the reaction correlated well with the Hammett σ- parameter with p= -0.39 ± 0.03; r2 = 0.93. The negative p value and secondary isotope effects are consistent with the rate-determining step being the formation of styrene from the prenylated flavin-product adduct through a cyclo-elimination reaction.
- Ferguson, Kyle L.,Arunrattanamook, Nattapol,Marsh, E. Neil G.
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p. 2857 - 2863
(2016/07/16)
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- Polyaniline-anchored palladium catalyst-mediated Mizoroki-Heck and Suzuki-Miyauraa reactions and one-pot Wittig-Heck and Wittig-Suzuki reactions
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A polyaniline-anchored palladium catalyst was prepared and screened for coupling reactions of aryl halides. The robust and recyclable catalyst was effective in Mizoroki-Heck and Suzuki-Miyaura reactions of aryl bromides and aryl iodides. The catalyst system was further employed for one-pot Wittig-Heck and Wittig-Suzuki combinations to build conjugated compounds in good conversions.
- Patel, Heta A.,Patel, Arun L.,Bedekar, Ashutosh V.
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- In Situ Generation of Formaldehyde and Triphenylphosphine from (Hydroxymethyl)triphenylphosphonium and Its Application in Wittig Olefination
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The reaction of (hydroxymethyl)triphenylphosphonium with benzylic or allylic halide under basic conditions at room temperature affords terminal alkenes in 61-89% yields. In this reaction, both formaldehyde and triphenylphosphine are in situ generated from (hydroxymethyl)triphenylphosphonium and further undergo Wittig olefination with benzylic or allylic halide.
- Huang, Wenhua,Xu, Jie
-
supporting information
p. 1777 - 1782
(2015/08/06)
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- Preparation of functional styrenes from biosourced carboxylic acids by copper catalyzed decarboxylation in PEG
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A general protocol for the copper-catalyzed decarboxylation of α,β-unsaturated carboxylic acids in PEG, particularly of biosourced cinnamic acid analogues, is reported. Moderate to high isolated yields (31-96%) towards the styrene derivatives were obtained. For the first time, decarboxylation of α-amino acids to the corresponding amines was successfully performed with good to high yields and extended to the decarboxylation of a few condensed heterocyclic compounds. Both the use of PEG as a green solvent and direct separation of the pure product of the reaction by distillation permitted the reuse of the solvent and the Cu-based catalytic system over several cycles without deactivation. This was extended to the synthesis of 4-vinylguaiacol on the laboratory scale in an average 92% yield. This journal is the Partner Organisations 2014.
- Cadot, Stephane,Rameau, Nelly,Mangematin, Stephane,Pinel, Catherine,Djakovitch, Laurent
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supporting information
p. 3089 - 3097
(2014/06/10)
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- Oxidative alkoxycarbonylation of terminal alkenes with carbazates
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A range of terminal alkenes smoothly underwent palladium-catalyzed oxidative alkoxycarbonylation with carbazates under an oxygen atmosphere to afford structurally diverse α,β-unsaturated esters in moderate to good yields with excellent regioselectivity and E selectivity.
- Su, Yu-Han,Wu, Zhao,Tian, Shi-Kai
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supporting information
p. 6528 - 6530
(2013/07/26)
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- Compounds for use as therapeutic agents affecting p53 expression and/or activity
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The present invention relates to compound (I) wherein R1 and R2 independently represent a hydrogen atom, a (C1-C4)alkoxy group, a fluoro(C1-C4)alkoxy group, a hydroxyl group, a benzyloxy group, a di(C1-C4)alkylamino group, a pyridyl-vinyl group, a pyrimidinyl-vinyl group, a styryl group, or a -NHCOphenyl group; R3, R4 and R5 independently represent a hydrogen atom, a (C1-C4)alkyl group, a CONHR6 group, a -CONR7R8 group, a -SO2NHR6 group, or a heteroaryl group optionally substituted by a halogen atom, a -(CH2)nNR7R8 group or a hydroxy(C1-C4)alkyl group; R6 represents a hydrogen atom, a -(CHR9)m(CH2)nNR7R8 group or a (C1-C6)alkyl group optionally substituted by a hydroxyl group; or anyone of its pharmaceutically acceptable salt, for use as an agent for preventing, inhibiting or treating a disease in a patient suffering thereof, said disease involving a deregulated p53. Some of said compounds are new and also form part of the invention.
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Page/Page column 47
(2012/10/18)
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- Fluorous oxime palladacycle: A precatalyst for carbon-carbon coupling reactions in aqueous and organic medium
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To facilitate precatalyst recovery and reuse, we have developed a fluorous, oxime-based palladacycle 1 and demonstrated that it is a very efficient and versatile precatalyst for a wide range of carbon-carbon bond formation reactions (Suzuki-Miyaura, Sonogashira, Stille, Heck, Glaser-type, and Kumada) in either aqueous or organic medium under microwave irradiation. Palladacycle 1 could be recovered through F-SPE in various coupling reactions with recovery ranging from 84 to 95% for the first cycle. Inductively coupled plasma optical emission spectrometry (ICP-OES) analyses of the Pd content in the crude product from each class of transformation indicated extremely low levels of leaching and the palladacycle could be reused four to five times without significant loss of activity.
- Susanto, Woen,Chu, Chi-Yuan,Ang, Wei Jie,Chou, Tzyy-Chao,Lo, Lee-Chiang,Lam, Yulin
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experimental part
p. 2729 - 2742
(2012/05/21)
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- An easy access to styrenes: Trans aryl 1,3-, 1,4- and 1,5-dienes, and 1,3,5-trienes by Hiyama cross-coupling catalyzed by palladium nanoparticles
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A convenient and efficient procedure has been developed for the vinylation of aryl-, styrenyl-, cinnamyl- and dienyl-halides by a Pd(0) nanoparticle-catalyzed Hiyama cross-coupling to provide the corresponding dienes and trienes in high yields. The reaction does not require any ligand or co-catalyst, and is carried out using PdCl2 and tetrabutyl ammonium fluoride (TBAF) in THF. Pd nanoparticles are generated in situ and are the active catalytic species in this reaction. A wide range of functionalized styrenes, trans aryl 1,3-, 1,4- and 1,5- dienes, 1,2-, 1-3 and 1,4-bis(1,3-dienes), and 1,3,5-trienes can be obtained by this procedure. The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2011.
- Chatterjee, Tanmay,Dey, Raju,Ranu, Brindaban C.
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experimental part
p. 1103 - 1110
(2011/07/08)
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- Generation of the CF3 radical from trifluoromethylsulfonium triflate and its trifluoromethylation of styrenes
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The CF3 radical was generated from the reaction of S-(trifluoromethyl)diphenylsulfonium triflate with Na2S 2O4 or HOCH2SO2Na under suitable conditions without further reduction. Based on this, a method for the synthesis of α-trifluoromethylated ketones has been successfully developed.
- Zhang, Cheng-Pan,Wang, Zong-Ling,Chen, Qing-Yun,Zhang, Chun-Tao,Gu, Yu-Cheng,Xiao, Ji-Chang
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supporting information; experimental part
p. 6632 - 6634
(2011/06/27)
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- Highly selective and potent μ opioid ligands by unexpected substituent on morphine skeleton
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Unexpected substituent on the well-known morphine skeleton is described to be account for highly selective and potent μ opioid ligands, which is strongly connected to substituted aromatic groups on this omitted 8α-position.
- Li, Wei,Tao, Yi-Min,Tang, Yun,Xu, Xue-Jun,Chen, Jie,Fu, Wei,Wang, Xing-Hai,Chao, Bo,Sheng, Wei,Xie, Qiong,Qiu, Zhui-Bai,Liu, Jing-Gen
-
supporting information; body text
p. 418 - 421
(2010/03/25)
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- Vinylation of aromatic halides using inexpensive organosilicon reagents. Illustration of design of experiment protocols
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The preparation of styrenes by palladium-catalyzed cross-coupling of aromatic iodides and bromides with divinyltetramethyldisiloxane (DVDS) in the presence of inexpensive silanolate activators has been developed. To facilitate the discovery of optimal reaction conditions, Design of Experiment (DoE) protocols were used. By the guided selection of reagents, stoichiometries, temperatures, and solvents, the vinylation reaction was rapidly optimized with three stages consisting of ca. 175 experiments (of a possible 1440 combinations). A variety of aromatic iodides undergo cross-coupling at room temperature in the presence of potassium trimethylsilanoate using Pd(dba) 2 in DMF in good yields. Triphenylphosphine oxide is needed to extend catalyst lifetime. Application of these conditions to aryl bromides was accomplished by the development of two complementary protocols. First, the direct implementation of the successful reaction conditions using aryl iodides at elevated temperature in THF provided the corresponding styrenes in good to excellent yields. Alternatively, the use of potassium triethylsilanolate and a bulky "Buchwald-type" ligand allows for the vinylation reactions to occur at or just above room temperature. A wide range of bromides underwent coupling in good yields for each of the protocols described.
- Denmark, Scott E.,Butler, Christopher R.
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p. 3690 - 3704
(2008/10/09)
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- Efficient heterogeneous vinylation of aryl halides using potassium vinyltrifluoroborate
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An efficient heterogeneously palladium catalysed procedure for the vinylation of aryl iodides and bromides is reported. Using common reaction conditions (Pd/C 2 mol %, AcONa·3H2O, NMP or NMP/H2O), good to complete conversions (40-100%) with high selectivities (79-100%) towards the expected vinylaromatic were achieved.
- Joucla, Lionel,Cusati, Giuseppe,Pinel, Catherine,Djakovitch, Laurent
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p. 4738 - 4741
(2008/12/21)
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- Copper-carbene complexes as catalysts in the synthesis of functionalized styrenes and aliphatic alkenes
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(NHC)-Cu (NHC = N-heterocyclic carbene) complexes efficiently catalyzed the methylenation of a variety of aliphatic and aromatic aldehydes and ketones in the presence of trimethylsilyldiazomethane, triphenylphosphine, and 2-propanol. The copper catalysts are not only inexpensive compared to rhodium complexes, but they also exhibit better functional group compatibility with aromatic aldehydes and ketones. Indeed very high yields were obtained for the formation of styrenes containing nitro, trifluoromethyl, amino, and ester groups, as well as for pyridine-, pyrrole-, and indole-substituted alkenes.
- Lebel, Helene,Davi, Michael,Diez-Gonzalez, Silvia,Nolan, Steven P.
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p. 144 - 149
(2007/10/03)
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- Enantioconvergent hydrolysis of styrene epoxides by newly discovered epoxide hydrolases in mung bean
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Two novel epoxide hydrolases were discovered in mung bean (Phaseolus radiatus L.) for the first time, either of which can catalyze enantioconvergent hydrolysis of styrene epoxides. Their regioselectivity coefficients are more than 90% for the p-nitrostyrene oxide. Furthermore, the crude mung bean powder was also shown to be a cheap and practical biocatalyst, allowing a one-step asymmetric synthesis of chiral (R)-diols from racemic epoxides, in up to >99% ee and 68.7% overall yield (after recrystallization).
- Xu, Wei,Xu, Jian-He,Pan, Jiang,Gu, Qing,Wu, Xin-Yan
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p. 1737 - 1740
(2007/10/03)
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- Tetraorganoindates as Nucleophilic Coupling Partners in Pd-Catalyzed Cross-Coupling Reactions
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(Equation presented) In situ generated ate complex In situ-generated tetraorganoindate complexes from the reaction of 1 equiv of indium trichloride with 4 equiv of appropriate organometallics are efficient nucleophiles in Pd-catalyzed cross-coupling reactions. In this novel reaction tetraorganoindates containing methyl, 1°- and 2°-alkyl, vinyl, alkynyl, and aryl groups transfer the four organic groups to a variety of electrophiles with high atom efficiency.
- Lee, Phil Ho,Lee, Sung Wook,Seomoon, Dong
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p. 4963 - 4966
(2007/10/03)
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- Novel irreversible butyrylcholinesterase inhibitors: 2-chloro-1-(substituted-phenyl)ethylphosphonic acids.
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2-Chloroethylphosphonic acid (ethephon) as the dianion phosphorylates butyrylcholinesterase (BChE) at its active site. In contrast, the classical organophosphorus esterase inhibitors include substituted-phenyl dialkylphosphates (e.g., paraoxon) with electron-withdrawing aryl substituents. The chloroethyl and substituted-phenyl moieties are combined in this study as 2-chloro-1-(substituted-phenyl)ethylphosphonic acids (1) to define the structure--activity relationships and mechanism of BChE inhibition by ethephon and its analogues. Phenyl substituents considered are 3- and 4-nitro, 3- and 4-dimethylamino, and 3- and 4-trimethylammonium. Phosphonic acids were synthesized via the corresponding O,O-diethyl phosphonate precursors followed by deprotection with trimethylsilyl bromide. They decompose under basic conditions about 100-fold faster than ethephon to yield the corresponding styrene derivatives. Electron-withdrawing substituents on the phenyl ring decrease the hydrolysis rate while electron-donating substituents increase the rate. The 4-trimethylammonium analogue has the highest affinity (K(i)=180 microM) and potency (IC(50)=19 microM) in first binding reversibly at the substrate site (possibly with stabilization in a dianion--monoanion environment) and then progressively and irreversibly inhibiting the enzyme activity. These observations suggest dissociation of chloride as the first and rate-limiting step both in the hydrolysis and by analogy in phosphorylation of BChE by bound at the active site.
- Zhang, Nanjing,Casida, John E
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p. 1281 - 1290
(2007/10/03)
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- Cross-coupling of vinylpolysiloxanes with aryl iodides
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Commercially available vinylpolysiloxane (1) rapidly undergoes cross-coupling reactions with aryl and alkenyl iodides in the presence of tetrabutylammonium fluoride (two to three equivalents) and Pd(dba)2 (1-5 mol%) at room temperature to affor
- Denmark, Scott E.,Wang, Zhigang
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p. 372 - 375
(2007/10/03)
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- Synthesis of styrenes through the biocatalytic decarboxylation of trans-cinnamic acids by plant cell cultures
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A novel method for producing styrenes from trans-cinnamic acids was developed. When trans-cinnamic acid was incubated with plant cell cultures at room temperature, styrene was obtained. 4-Hydroxy-3-methoxystyrene (2a), 3-nitrostyrene (2f) and furan (2g) were synthesized quantitatively.
- Takemoto,Achiwa
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p. 639 - 641
(2007/10/03)
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- 1-methyl-1-vinyl- and 1-methyl-1-(prop-2-enyl)silacyclobutane: Reagents for palladium-catalyzed cross-coupling reactions of aryl halides
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1-Methyl-1-vinylsilacyclobutane (1) and 1-methyl-1(prop-2- enyl)silacyclobutane (2) undergo rapid and high yielding cross-coupling with aromatic halides. Many different substituents and patterns on the aromatic moiety are tolerated. All reactions can be r
- Denmark, Scott E.,Wang, Zhigang
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p. 999 - 1003
(2007/10/03)
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- Effect of cyclodextrin on elimination reactions
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The reaction of 1-bromo-2-X-2-(Y-phenyl) ethane derivatives (1: X = Y = H; 2: X = Ph, Y = H; 3: X = H, Y = 4-Ac; 4: X = H, Y = 3-NO2; 5: X = H, Y = 4-NO2; 6: X = H, Y = 3-Me; 7: X = H, Y = 4-Me) in basic solution was studied, and in most cases, only the elimination product is formed. Only (2-bromo-1-phenylethyl)benzene, 2, yielded significant substitution product, and this yield decreased with the concentration of HO-. Addition of cyclodextrin (β-CD) diminished (about half for 0.02 M cyclodextrin concentration) the reaction rate of all substrates but 4 and 5. In the latter two cases, the rate rises. The observed rate-constant value at 0.5 M NaOH is 6.78 × 104 s-1 (at 40°C) and 1.80 × 10-3 s-1 (at 25°C) for 4 and 5, respectively. Under the same reaction conditions but with 0.01 M β-CD, the corresponding rates were 7.70 × 10-4 s-1 and 5.20 × 10-3 s-1. The elimination yield for 2 increased from 64 to 98% when the β-CD changed from zero to 0.02 M at 0.5 M NaHO. Also, there was an increase in the relative elimination products of 20-40% for compounds 6 and 7. The Hammet ρ values were 1.3 and 2.3 for the reaction in pure solvent and in the presence of β-cyclodextrin, indicating an increase in the negative character of the transition state for the reactions in the latter conditions. The results are interpreted in terms of the formation of an inclusion complex whose structure depends on the substrate.
- Viola, Luis,De Rossi, Rita H.
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p. 860 - 867
(2007/10/03)
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- Synthesis of styrenes through the decarboxylation of trans-cinnamic acids by plant cell cultures
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A new method has been developed for the synthesis of styrenes through the decarboxylation of trans-cinnamic acids by plant cell cultures at room temperature. 4-Hydroxy-3-methoxystyrene (2a), 3-nitrostyrene (2d) and furan (2e) were synthesized quantitatively.
- Takemoto, Masumi,Achiwa, Kazuo
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p. 6595 - 6598
(2007/10/03)
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- Oxidative addition of dimethyl malonate to styrenes mediated by cerium(IV) ammonium nitrate: Some novel observations
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The oxidative addition of dimethyl malonate to ring substituted styrenes leads to the formation of substituted dimethyl (2-oxo-2-phenylethyl) malonate and methyl 2-oxo-5-phenyltetrahydrofuran-3-carboxylate along with small amounts of substituted dimethyl [2-(nitrooxy)-2-phenylethyl] malonate and dimethyl 2-methoxy-2-phenylethyl) malonate. A tentative mechanism which supports the formation of these products is also presented.
- Nair, Vijay,Mathew, Jessy,Nair, Latha G.
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p. 3053 - 3064
(2007/10/03)
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- Kynurenic acid derivatives useful in the treatment of neurodegenerative disorders
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4-Oxo-1,4-dihydroquinoline compounds having a 2-acidic group or a group convertible thereto in vivo, and their pharmaceutically acceptable salts, are potent specific antagonists of N-methyl-D-aspartate (NMDA) receptors and are therefore useful in the treatment of neurodegenerative disorders. 4-Oxo-1,4-dihydroquinoline compounds having a 2-acidic group or a group convertible thereto in vivo, other than carboxy or C 1-6 alkoxycarbonyl, are novel compounds, as also are compounds of formula II STR1 wherein R 2 represents carboxy or a group convertible thereto in vivo, R 6 is hydrogen and R 5 and R 7 represent C 1-6 alkyl or halogen, provided that R 5 and R 7 are not simultaneously chlorine or simultaneously bromine; a process for preparing the novel compounds is described, as also are pharmaceutical compositions containing the novel compounds.
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- Palladium-Catalyzed Arylation of Unsymmetrical Olefins. Bidentate Phosphine Ligand Controlled Regioselectivity
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The palladium-catalyzed arylation of several unsymmetrical olefins by aryl triflates in the presence of bidentate phosphine ligands is described.The use of these ligands increases the influence that electronic factors have in determining the regioselectivity of the reaction.The catalyst performances allow a revisiting of the scheme that describes the regioselectivity outcome in Heck-type reactions.Furthermore, a general mechanism for the palladium-catalyzed arylation of olefins is proposed.
- Cabri, Walter,Candiani, Ilaria,Bedeschi, Angelo,Santi, Roberto
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p. 3558 - 3563
(2007/10/02)
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- A High-Yield Regiospecific Synthesis of Keto Oximes from Aryl-Conjugated Ethylenes and Ethyl Nitrite in the Presence of Cobalt Complex and BH4- Ion
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The title reaction of substituted styrenes, 1-phenyl-1,3-butadiene, and some cyclic aryl-conjugated ethylenes proceeds smoothly at room temperature, affording the corresponding oximes in moderate to nearly quantitative yields.The reaction mechanism is discussed on the basis of the formation of an alkylcobalt intermediate and its subsequent reaction with ethyl nitrite.
- Okamoto, Tadashi,Kobayashi, Kenji,Oka, Shinzaburo,Tanimoto, Shigeo
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p. 4897 - 4901
(2007/10/02)
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- Addition of Arenesulphonyl Iodides to Substituted Phenylacetylenes
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The products of the addition of toluene-p-sulphonyl iodide to substituted phenylacetylenes (and styrenes) are studied.The regiospecificity and stereoselectivity of trans addition to acetylenes is inferred from (1)H n.m.r. spectroscopy.The effect of substituents on the reactivity of substituted phenylacetylenes towards substituted beenzenesulphonyl radicals generated by photolysis of sulphonyl iodides is studied.Phenylacetylenes with electron-donating substituents react faster.Relative reactivities yield good Hammet-Brown correlations showing the electrophilic character of sulphonyl radicals towards phenylacetylenes.The selectivity of the addition (measured by ρ) of different sulphonyl radicals towards the same set of acetylenes ranges from -0.53 to -0.93 and shows a tendency to be smaller for benzenesulphonyl iodides carrying electron donating substituents.Results are discussed in terms of polar effects on the transition state and frontier molecular orbital theory.
- Silva Correa, Carlos M. M. da,Fleming, Maria Daniela C. M.
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p. 103 - 108
(2007/10/02)
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- Heavy Atom Isotope Effect Studies of Elimination Reaction Mechanisms. 1. A Kinetic and Carbon-14 Kinetic Isotope Effect Study of the Base-Promoted Dehydrochlorination of Substituted 1-Phenylethyl-2-14C Chlorides
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Upon treatment with the solvent conjugate base, the primary reaction of substituted 1-phenyl chloride is elimination to substituted styrenes in t-BuOH-10percent v/v Me2SO at 60 deg C and in bis(2-hydroxyethyl) ether-10percent v/v Me2SO at 45 deg C.Kinetics studies using eight substituted chlorides show that these reactions are strongly accelerated by both electron-donating and electron-withdrawing substituents, probably indicating a fairly reactant-like E2 transition state with the mechanism changing from E1-like E2 to E1cB-like E2 as the substituents change from EDG to EWG.In this first carbon isotope effect study of an elimination reaction of an alkyl chloride, carbon-14 kinetic isotope effects have been measured in the alkoxide/bis(2-hydroxyethyl) ether-Me2SO system for 1-(4-methylphenyl)ethyl-2-14C chloride, k/βk = 1.038, 1-phenylethyl-2-14C chloride, k/βk = 1.058, and 1-(4-chlorophenyl)ethyl-2-14C chloride, k/βk = 1.068.Clearly none of these compounds reacts by an irreversible E1 mechanism, for which no β-carbon isotope effect should be observed.The trend in the results is what would be expected from increased Cβ-H bond rupture as the E2 transition state shifts from E1-like to E1cB-like.Theoretical calculations involving E1-like E2 transition-state models show that in this region only for a reaction coordinate motion that strongly couples Cβ-H bond rupture, Cα-Cβ double bond formation, and Cα-Cl bond rupture does the calculated value for k/βk come into the experimentally observed range, and then only for reactant-like models.
- Hasan, Tayyaba,Sims, Leslie B.,Fry, Arthur
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p. 3967 - 3975
(2007/10/02)
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- Mercury in Organic Chemistry. 25. Rhodium(I)-Catalyzed Alkenylation of Arylmercurials
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Arylmercurials and vinyl halides are catalytically cross-coupled to aryl olefins in fair to good yields by 10percent ClRh(PPh3)3.This reaction appears to proceed through an arylvinylrhodium(III) intermediate.
- Larock, R. C.,Narayanan, K.,Hershberger, S. S.
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p. 4377 - 4380
(2007/10/02)
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