- Regioselective hydrosilylation of terminal acetylenes via acetylene-Co 2(CO)4dppm complex: Effects of the ligands in acetylenedicobalt complex
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The regioselective hydrosilylation of the acetylenedicobalt complex on the terminal acetylene with special reference to the ligands to produce a vinylsilane is described. It was found that the use of the ligands exchanged dicobalttetracarbonyl bis(diphenylphosphino)methane complex dramatically changed the regioselectivity compared to the corresponding dicobalthexacarbonyl complex.
- Tojo, Shingo,Isobe, Minoru
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- Manganese-Catalyzed Dehydrogenative Silylation of Alkenes following Two Parallel Inner-Sphere Pathways
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We report on an additive-free Mn(I)-catalyzed dehydrogenative silylation of terminal alkenes. The most active precatalyst is the bench-stable alkyl bisphosphine Mn(I) complex fac-[Mn(dippe)(CO)3(CH2CH2CH3)]. The catalytic process is initiated by migratory insertion of a CO ligand into the Mn-alkyl bond to yield an acyl intermediate which undergoes rapid Si-H bond cleavage of the silane HSiR3 forming the active 16e- Mn(I) silyl catalyst [Mn(dippe)(CO)2(SiR3)] together with liberated butanal. A broad variety of aromatic and aliphatic alkenes was efficiently and selectively converted into E-vinylsilanes and allylsilanes, respectively, at room temperature. Mechanistic insights are provided based on experimental data and DFT calculations revealing that two parallel reaction pathways are operative: an acceptorless reaction pathway involving dihydrogen release and a pathway requiring an alkene as sacrificial hydrogen acceptor.
- Weber, Stefan,Glavic, Manuel,St?ger, Berthold,Pittenauer, Ernst,Podewitz, Maren,Veiros, Luis F.,Kirchner, Karl
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supporting information
p. 17825 - 17832
(2021/11/04)
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- Manganese-catalysed divergent silylation of alkenes
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Transition-metal-catalysed, redox-neutral dehydrosilylation of alkenes is a long-standing challenge in organic synthesis, with current methods suffering from low selectivity and narrow scope. In this study, we report a general and simple method for the manganese-catalysed dehydrosilylation and hydrosilylation of alkenes, with Mn2(CO)10 as a catalyst precursor, by using a ligand-tuned metalloradical reactivity strategy. This enables versatility and controllable selectivity with a 1:1 ratio of alkenes and silanes, and the synthetic robustness and practicality of this method are demonstrated using complex alkenes and light olefins. The selectivity of the reaction has been studied using density functional theory calculations, showing the use of an iPrPNP ligand to favour dehydrosilylation, while a JackiePhos ligand favours hydrosilylation. The reaction is redox-neutral and atom-economical, exhibits a broad substrate scope and excellent functional group tolerance, and is suitable for various synthetic applications on a gram scale. [Figure not available: see fulltext.].
- Dong, Jie,Yuan, Xiang-Ai,Yan, Zhongfei,Mu, Liying,Ma, Junyang,Zhu, Chengjian,Xie, Jin
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p. 182 - 190
(2020/12/17)
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- Rh(I)/(III)-N-Heterocyclic Carbene Complexes: Effect of Steric Confinement Upon Immobilization on Regio- and Stereoselectivity in the Hydrosilylation of Alkynes
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Rh(I) NHC and Rh(III) Cp* NHC complexes (Cp=pentamethylcyclopentadienyl, NHC=N-heterocyclic carbene=pyrid-2-ylimidazol-2-ylidene (Py?Im), thiophen-2-ylimidazol-2-ylidene) are presented. Selected catalysts were selectively immobilized inside the mesopores
- Atwi, Boshra,Bauer, Matthias,Buchmeiser, Michael R.,Frey, Wolfgang,Nowakowski, Michal,Panyam, Pradeep K. R.,Ziegler, Felix
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supporting information
p. 17220 - 17229
(2021/11/10)
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- Atomically dispersed gold anchored on carbon nitride nanosheets as effective catalyst for regioselective hydrosilylation of alkynes
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The hydrosilylation of alkynes is a powerful process for producing vinylsilane compounds, which are synthetically versatile organosilicon reagents in organic chemistry. Herein, atomically dispersed Au anchored on g-C3N4 nanosheets is developed as a superi
- Chen, Zheng,Feng, Xueqing,Guo, Jiahui,Wang, Songrui,Wu, Qikang
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supporting information
p. 17885 - 17892
(2021/08/30)
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- Short-chained platinum complex catalyzed hydrosilylation under thermomorphic conditions: Heterogeneous phase separation at ice temperature
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Homogeneous catalysts PtCl2 [5,5′-bis-(n-ClCF2 (CF2 )3 CH2 OCH2 )-2,2′-bpy] (2A) and PtCl2 [5,5′-bis-(n-HCF2 (CF2 )3 CH2 OCH2 )-2,2′-bpy] (2B), which contained short fluorous chains, were synthe-sized and used in catalysis of hydrosilylation of alkynes. In these reactions the thermomorphic mode was effectively used to recover these catalysts from the reaction mixture up to eight cycles by taking advantage of heterogeneous phase separation at ice temperature. This kind of catalysis had previously been observed in fluorous catalysts of platinum containing about 50% F-content, but in this work the percentage of F-content is decreased to only about 30%, by which we termed them as “very light fluorous”. Our new type of catalyst with limited number of F-content is considered as the important discovery in the fluorous technology field as the reduced number of fluorine atoms will help to be able to comply the EPA 8-carbon rule. The metal leaching after the reaction has been examined by ICP-MS, and the testing results show the leaching of residual metal to be minimal. Additionally, comparing these results to our previous work, fluorous chain assisted selectivity has been observed when different fluorous chain lengths of the catalysts are used. It has been found that there exists fluorous chain assisted better selectivity towards β-(E) form in the Pt-catalyzed hydrosilylation of non-symmetric terminal alkyne when the Pt catalyst contains short fluorous chain (i.e., 4 Cs). Phenyl acetylenes showed the opposite regioselectivity due to pi-pi interaction while using the same catalyst via Markovnikov’s addition to form terminal vinyl silane, which is then a major product for Pt-catalyzed hydrosilylation of terminal aryl acetylene with triethylsilane. Finally, the kinetic studies indicate that the insertion of alkyne into the Pt-H bond is the rate-determining step.
- Chiu, Chiao-Fan,Ho, Jinn-Hsuan,Lin, Chang-Wei,Lu, Norman,Lu, Yijing,Shen, Chia-Rui,Tessema, Eskedar
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supporting information
(2021/06/28)
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- Carboxylate-Assisted β-(Z) Stereoselective Hydrosilylation of Terminal Alkynes Catalyzed by a Zwitterionic Bis-NHC Rhodium(III) Complex
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The zwitterionic compound [Cp*RhCl{(MeIm)2CHCOO}] is an efficient catalyst for the hydrosilylation of terminal alkynes with excellent regio- and stereoselectivity toward the less thermodynamically stable β-(Z)-vinylsilane isomer under mild reaction conditions. A broad range of linear 1-alkynes, cycloalkyl acetylenes, and aromatic alkynes undergo the hydrosilylation with HSiMe2Ph to afford the corresponding β-(Z)-vinylsilanes in quantitative yields in short reaction times. The reaction of aliphatic alkynes with HSiEt3 is slower, resulting in a slight decrease of selectivity toward the β-(Z)-vinylsilane product, which is still greater than 90%. However, a significant selectivity decrease is observed in the hydrosilylation of aromatic alkynes because of the β-(Z) → β-(E) vinylsilane isomerization. Moreover, the hydrosilylation of bulky alkynes, such as t-Bu-CCH or Et3SiCCH, is unselective. Experimental evidence suggests that the carboxylate function plays a key role in the reaction mechanism, which has been validated by means of density functional theory calculations, as well as by mass spectrometry and labeling studies. On the basis of previous results, we propose an ionic outer-sphere mechanism pathway in which the carboxylate fragment acts as a silyl carrier. Namely, the hydrosilylation mechanism entails the heterolytic activation of the hydrosilane assisted by the carboxylate function to give the hydrido intermediate [Cp*RhH{(MeIm)2CHCOO-SiR3}]+. The transference of the silylium moiety from the carboxylate to the alkyne results in the formation of a flat β-silyl carbocation intermediate that undergoes a hydride transfer from the Rh(III) center to generate the vinylsilane product. The outstanding β-(Z) selectivity results from the minimization of the steric interaction between the silyl moiety and the ligand system in the hydride transfer transition state.
- Puerta-Oteo, Raquel,Munarriz, Julen,Polo, Víctor,Jiménez, M. Victoria,Pérez-Torrente, Jesús J.
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p. 7367 - 7380
(2020/07/21)
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- [Rh(Cod)Cl]2/Pph3?catalyzed dehydrogenative silylation of styrene derivatives with NBE as a hydrogen acceptor
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Direct synthesis of arylalkenylsilanes by [Rh(COD)Cl]2/ PPh3-catalyzed dehydrogenative silylation of styrene derivatives with R3SiH (R = alkyl, alkoxy, aryl) was realized, in which norbornene (NBE) and PPh3 play a key role in achieving excellent selectivity in the formation of dehydrogenative silylation products. Moreover, this high-yielding transformation exhibits a broad substrate scope and good functional group tolerance.
- Li, Chengyang,Lu, Wenkui,Wu, Xiaoyu,Xie, Xiaomin,Zhang, Zhaoguo
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p. 3780 - 3788
(2020/11/23)
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- A Platinum Molecular Complex Immobilised on the Surface of Graphene as Active Catalyst in Alkyne Hydrosilylation
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A platinum complex bearing a N-heterocyclic carbene (NHC) ligand functionalised with a pyrene-tag is immobilised onto the surface of reduced graphene oxide (rGO). The hybrid material composed of an organometallic complex and a graphene derivative is ready
- Mollar-Cuni, Andres,Borja, Pilar,Martin, Santiago,Guisado-Barrios, Gregorio,Mata, Jose A.
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supporting information
p. 4254 - 4262
(2020/06/08)
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- Dichloro(ethylenediamine)platinum(II), a water-soluble analog of the antitumor cisplatin, as a heterogeneous catalyst for a stereoselective hydrosilylation of alkynes under neat conditions
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A stereoselective method for the hydrosilylation of internal and terminal alkynes under heterogeneous catalysis by dichloro(ethylenediamine)platinum(II) is discussed. This commercially available platinum complex operates under neat conditions at 90 °C, pr
- Fotie, Jean,Enechojo Agbo, Mercy,Qu, Fengrui,Tolar, Trevor
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supporting information
(2020/08/13)
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- Method for selective preparation of alkenyl silane
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A method for realizing selective silylation of terminal olefin by ligand regulation is disclosed. According to the method, terminal olefin and trisubstituted silane, which are used as raw materials, and trifluorotoluene, which is used as a solvent, react
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Paragraph 0019; 0020
(2019/10/01)
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- Nickel-Catalyzed Decarboxylative C–Si Bond Formation: A Regioselective Cross-Coupling Between Trialkyl Silanes and α,β-Unsaturated Carboxylic Acids
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This report presents the first example of nickel-catalyzed mild decarboxylative cross-coupling reaction for the regioselective formation of C–Si bond. An easily accessible and significantly stable Ni (dmg)2 owes the role of key promoter. This r
- Allam, Bharat Kumar,Azeez, Sadaf,Kandasamy, Jeyakumar
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- A Rh(I) complex with an annulated N-heterocyclic carbene ligand for E-selective alkyne hydrosilylation
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A Rh(I) complex supported by a fused π-conjugated imidazo[1,2-a][1,8]naphthyridine-based N-heterocyclic carbene ligand with a Dipp attachment on the imidazole nitrogen has been synthesized and structurally characterized. The title complex is found to be a
- Tyagi, Akshi,Yadav, Suman,Daw, Prosenjit,Ravi, Chitrakar,Bera, Jitendra K.
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p. 167 - 174
(2019/05/15)
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- Platinum nanoparticles confined in imidazolium-based ionic polymer for assembling a microfluidic reactor with enhanced catalytic activity
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A synthetic strategy is developed to grow Pt nanoparticles supported by imidazolium-based ionic polymers (Pt/ImIP-2BrB) on the inner surface of fused-silica capillary. The imidazolium-based ionic polymers ImIP-2BrB are prepared from condensation of tetrakis[4-(1-imidazolyl)phenyl]methane and 1,4-bis-bromomethyl-benzene and are employed to support Pt nanoparticles. The capillary coated with Pt/ImIP-2BrB is further assembled to achieve a catalytic micro?uidic reactor. The catalytic activity is probed in either the reduction of nitrobenzene derivatives or the hydrosilylation of phenylacetylene with triethylsilane by flowing through the micro?uidic reactor. The catalytic micro?uidic reactor demonstrates significantly enhanced activity about 2–8 times in comparison with the corresponding reactions under batch conditions. The reactor greatly reduces the amount of Pt upon achieving similar yields. It also shows good recyclability without significant decrease of the activity.
- Fang, Haobin,Chen, Junxing,Xiao, Yali,Zhang, Jianyong
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- FeCl2/DTBP: An efficient and highly E-selective cross - coupling of silanes with styrene and its derivatives
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An efficient FeCl2-catalyzed cross-coupling of silanes with styrene and its derivatives using DTBP as oxidant for selective synthesis of vinylsilanes was developed. This method presented an inexpensive, non-toxic and environmentally benign cata
- Xu, Rui,Cai, Chun
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- Metal-Free Catalytic Reductive Cleavage of Enol Ethers
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In contrast to the well-known reductive cleavage of the alkyl-O bond, the cleavage of the alkenyl-O bond is much more challenging especially using metal-free approaches. Unexpectedly, alkenyl-O bonds were reductively cleaved when enol ethers were reacted with Et3SiH and a catalytic amount of B(C6F5)3. Supposedly, this reaction is the result of a B(C6F5)3-catalyzed tandem hydrosilylation reaction and a silicon-assisted β-elimination. A mechanism for this cleavage reaction is proposed based on experiments and density functional theory (DFT) calculations.
- Chulsky, Karina,Dobrovetsky, Roman
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supporting information
p. 6804 - 6807
(2018/11/02)
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- A recyclable and reusable K2PtCl4/Xphos-SO3Na/PEG-400/H2O system for highly regio- and stereoselective hydrosilylation of terminal alkynes
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K2PtCl4/Xphos-SO3Na in a mixture of poly(ethylene glycol) (PEG-400) and water is shown to be a highly regio- and stereoselective catalyst for the hydrosilylation of terminal alkynes with hydrosilanes. The reaction could be conducted under mild conditions, yielding a variety of functionalized β-(E)-vinylsilanes in good to excellent yields with a total β-(E)-selectivity. The isolation of the products is readily performed by extraction with cyclohexane and more importantly, both expensive K2PtCl4 and Xphos-SO3Na in a PEG-400/H2O system could be easily recycled and reused at least eight times without any loss of catalytic activity.
- Xu, Caifeng,Huang, Bin,Yan, Tao,Cai, Mingzhong
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supporting information
p. 391 - 397
(2018/02/07)
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- Highly selective hydrosilylation of olefins and acetylenes by platinum(0) complexes bearing bulky N-heterocyclic carbene ligands
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Platinum complexes bearing bulky N-heterocyclic carbene (NHC) ligands, i.e., [Pt(IPr?)(dvtms)] (where, IPr? = 1,3-bis{2,6-bis(diphenylmethyl)-4-methylphenyl}imidazol-2-ylidene) and [Pt(IPr?OMe)(dvtms)] (where, IPr?OMe = 1,3-bis{2,6-bis(diphenylmethyl)-4-m
- Zak,Bo?t,Kubicki,Pietraszuk
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supporting information
p. 1903 - 1910
(2018/02/17)
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- Regio- and stereoselective hydrosilylation of alkynes catalyzed by SiO2 supported Pd-Cu bimetallic nanoparticles
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An efficient, recyclable Pd-Cu bimetallic nanoparticle catalyst has been prepared, which exhibits superior activity and selectivity toward the hydrosilylation of internal and terminal alkynes under mild reaction conditions with a low catalyst loading. Distinct enhancement in catalytic performance is observed when compared with traditional monometallic catalysts, and the composition of BMNPs is found to be crucial in both selectivity and yield. This kind of elevation in catalytic performance can be ascribed to the enrichment of active sites (Pd) on the catalyst surface and a phenomenon collectively referred to as "synergistic effects". The successful application of BMNPs as catalysts in the alkyne hydrosilylation opens up new possibilities for the excavation of the value of bimetallic nanoparticles in catalysts' development for sustainable chemistry.
- Zhang, Jia-Wei,Lu, Guo-Ping,Cai, Chun
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supporting information
p. 2535 - 2540
(2017/07/17)
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- Functionalized vinylsilanes via highly efficient and recyclable Pt-nanoparticle catalysed hydrosilylation of alkynes
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A mild, selective and facile synthesis of vinylsilanes via a recyclable platinum nanoparticle catalysed hydrosilylation of alkynes is reported. Various functionalized alkynes are selectively hydrosilylated to furnish functional β-E vinylsilanes in high yi
- Chauhan, Bhanu P. S.,Sarkar, Alok
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supporting information
p. 8709 - 8715
(2017/07/24)
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- Stereoselective synthesis of vinylsilanes: Via copper-catalyzed silylation of alkenes with silanes
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An efficient and stereoselective synthesis of vinylsilanes via copper-catalyzed direct silylation of alkenes with silanes was developed. This study offers a new and expedient strategy for the synthesis of synthetically useful alkenyl organosilicon compoun
- Gu, Jian,Cai, Chun
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supporting information
p. 10779 - 10782
(2016/09/07)
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- A Free-Radical-Promoted Stereospecific Decarboxylative Silylation of α,β-Unsaturated Acids with Silanes
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A stereospecific decarboxylative silylation of acrylic and propiolic acids with silanes was developed. This reaction represents the first example of decarboxylative C-Si bond formation and provides an efficient and convenient approach to various synthetically useful alkenyl and alkynyl organosilicon compounds through the reaction of α,β-unsaturated acids with silanes. Spin-trapping and EPR experiments support a radical addition/elimination process.
- Zhang, Lizhi,Hang, Zhaojia,Liu, Zhong-Quan
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supporting information
p. 236 - 239
(2016/01/25)
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- Solid supported palladium(0) nanoparticles: An efficient heterogeneous catalyst for regioselective hydrosilylation of alkynes and suzuki coupling of β-arylvinyl iodides
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The solid supported palladium(0) nanoparticles (NPs) were found as an active heterogeneous catalyst for regioselective hydrosilylation of alkynes with organosilanes in the presence of NaI as additive. Aliphatic as well as aromatic terminal/substituted alkynes with both electron releasing and withdrawing functionalities similarly participated in the hydrosilylation to produce regioselective β-isomers of vinylsilanes under mild reaction conditions. Reducible functional groups such as nitrile, ester, halide, alkene and alkyne were also found to be tolerated under this condition. Furthermore, the triethylsilylstyrene was applied for consecutive iododesilylation followed by Suzuki coupling reaction to produce stilbenes. The air/moisture stable SS-Pd catalyst was recycled for hydrosilylation reaction up to ten runs without significant loss of its catalytic activity. Graphical Abstract: Solid Supported Palladium(0) Nanoparticles: An Efficient Heterogeneous Catalyst for Regioselective Hydrosilylation of Alkynes and Suzuki Coupling of β-Arylvinyl Iodides[Figure not available: see fulltext.]
- Bal Reddy, C.,Shil, Arun K.,Guha, Nitul Ranjan,Sharma, Dharminder,Das, Pralay
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p. 1530 - 1536,7
(2014/10/15)
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- An alternative mechanistic paradigm for the β-Z hydrosilylation of terminal alkynes: The role of acetone as a silane shuttle
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The β-Z selectivity in the hydrosilylation of terminal alkynes has been hitherto explained by introduction of isomerisation steps in classical mechanisms. DFT calculations and experimental observations on the system [M(I)2{κ-C,C,O,O-(bis-NHC)}]BF4 (M=Ir (3 a), Rh (3 b); bis-NHC=methylenebis(N-2-methoxyethyl)imidazole-2-ylidene) support a new mechanism, alternative to classical postulations, based on an outer-sphere model. Heterolytic splitting of the silane molecule by the metal centre and acetone (solvent) affords a metal hydride and the oxocarbenium ion [R 3Si - O(CH3)2]+, which reacts with the corresponding alkyne in solution to give the silylation product [R 3Si - CHi£C - R]+. Thus, acetone acts as a silane shuttle by transferring the silyl moiety from the silane to the alkyne. Finally, nucleophilic attack of the hydrido ligand over [R3Si - CHi£C - R]+ affords selectively the β-(Z)- vinylsilane. The β-Z selectivity is explained on the grounds of the steric interaction between the silyl moiety and the ligand system resulting from the geometry of the approach that leads to β-(E)-vinylsilanes. Silanes catch the shuttle: An outer-sphere mechanism that explains the β-Z hydrosilylation of terminal alkynes based on the role of acetone as a silane shuttle is disclosed. Heterolytic splitting of the silane molecule by the metal centre and acetone affords a metal hydride and the oxocarbenium ion [R 3Si - O(CH3)2]+, which reacts with the alkyne in solution to give the silylation product [R3Si - CHi£C - R]+ (see figure).
- Iglesias, Manuel,Sanz Miguel, Pablo J.,Polo, Victor,Fernandez-Alvarez, Francisco J.,Perez-Torrente, Jesus J.,Oro, Luis A.
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p. 17559 - 17566
(2014/01/06)
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- A synthon for a 14-electron Ir(iii) species: Catalyst for highly selective β-(Z) hydrosilylation of terminal alkynes
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A synthon for a 14-electron Ir(iii) species is described. The geometrical control exerted by the ligand system over the Ir-alkenyl intermediate in hydrosilylation of terminal alkynes precludes formation of the more thermodynamically stable β-(E)-vinylsila
- Iglesias, Manuel,Perez-Nicolas, Maria,Miguel, Pablo J. Sanz,Polo, Victor,Fernandez-Alvarez, Francisco J.,Perez-Torrente, Jesus J.,Oro, Luis A.
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supporting information
p. 9480 - 9482
(2012/10/29)
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- Probing the catalytic potential of chloro nitrosyl rhenium(i) complexes
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The reduction of the mononitrosyl Re(ii) salt [NMe4] 2[ReCl5(NO)] (1) with zinc in acetonitrile afforded the Re(i) dichloride complex [ReCl2(NO)(CH3CN)3] (2). Subsequent ligand substitution reactions with PCy3, PiPr 3 and P(p-tolyl)3 afforded the bisphosphine Re(i) complexes [ReCl2(NO)(PR3)2(CH3CN)] (3, R = Cy a, iPr b, p-tolyl c) in good yields. The acetonitrile ligand in 3 is labile, permitting its replacement with H2 (1 bar) to afford the dihydrogen Re(i) complexes [ReCl2(NO)(PR3) 2(η2-H2)] (4, R = Cy a, iPr b). The catalytic activity of 2, 3 and 4 in hydrogen-related catalyses including dehydrocoupling of Me2NH·BH3, dehydrogenative silylation of styrenes, and hydrosilylation of ketones and aryl aldehydes were investigated, with the main focus on phosphine and halide effects. In the dehydrocoupling of Me2NH·BH3, the phosphine-free complex 2 exhibits the same activity as the bisphosphine-substituted systems. In the dehydrogenative silylation of styrenes, 3a and 4a bearing PCy3 ligands exhibit high catalytic activities. Monochloro Re(i) hydrides [Re(Cl)(H)(NO)(PR3)2(CH3CN)] (5, R = Cy a, iPr b) were proven to be formed in the initiation pathway. The phosphine-free complex 2 showed in dehydrogenative silylations even higher activity than the bisphosphine derivatives, which further emphasizes the importance of a facile phosphine dissociation in the catalytic process. In the hydrosilylation of ketones and aryl aldehydes, at least one rhenium-bound phosphine is required to ensure high catalytic activity.
- Jiang, Yanfeng,Blacque, Olivier,Berke, Heinz
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experimental part
p. 2578 - 2587
(2011/05/03)
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- Hydrosilylation of alkynes catalysed by platinum on titania
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The heterogeneous hydrosilylation of alkynes catalysed by platinum on titania is reported. A variety of hydrosilanes react with both terminal and internal alkynes to furnish the corresponding vinyl silanes in high yields and short reaction times as well as in a regio- and stereoselective manner. The catalyst can be easily recovered and reused in several consecutive cycles.
- Alonso, Francisco,Buitrago, Robison,Moglie, Yanina,Ruiz-Martínez, Javier,Sepúlveda-Escribano, Antonio,Yus, Miguel
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experimental part
p. 368 - 372
(2011/02/16)
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- Facile synthetic access to rhenium(II) complexes: Activation of carbonbromine bonds by single-electron transfer
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The five-coordinated Re1 hydride complexes [Re(Br)(H)(NO) (PR3)2] (R = Cy la, iPr lb) were reacted with benzylbromide, thereby affording the 17-electron mononuclear ReII hydride complexes [Re(Br)2(H)(NO)(PR3)2] (R = Cy 3a, iPr 3b), which were characterized by EPR, cyclic voltammetry, and magnetic susceptibility measurements. In the case of dibromomethane or bromoform, the reaction of 1 afforded ReII hydrides 3 in addition to Re1 carbene hydrides [Re(= CHR1)(Br)(H)(NO)(PR3)2,] (R 1 = H 4, Br 5; R = Cy a, iPr b) in which the hydride ligand is positioned cis to the carbene ligand. For comparison, the dihydrogen Re 1 dibromide complexes [Re(Br)2(NO)(PR3MIf- H2)] (R = Cy 2 a, iPr 2 b) were reacted with allyl- or benzylbromide, thereby affording the monophosphine ReII complex salts [R 3PCH2R'][Re(Br)4(NO)(PR3)] (R' = -CH=CH2 6, Ph 7). The reduction of ReII complexes has also been examined. Complex 3 a or 3 b can be reduced by zinc to afford la or lb in high yield. Under catalytic conditions, this reaction enables homocoupling of benzylbromide (turnover frequency (TOF): 3a 150, 3b 134 h-1) or allylbromide (TOF: 3a 150, 3b 562 h-1). The reaction of 6 a and 6 b with zinc in acetonitrile affords in good yields the monophosphine Re 1 complexes [Re(Br)2(NO)(MeCN)2(PR 3)] (R = Cy 8a, iPr 8b), which showed high catalytic activity toward highly selective dehydrogenative silylation of styrenes (maximum TOF of 61 h-1). Single-electron transfer (SET) mechanisms were proposed for all these transformations. The molecular structures of 3 a, 6 a, 6 b, 7 a, 7 b, and 8 a were established by single-crystal X-ray diffraction studies.
- Jiang, Yanfeng,Blacque, Olivier,Fox, Thomas,Freeh, Christian M.,Berke, Heinz
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scheme or table
p. 2240 - 2249
(2010/07/05)
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- Platinum(ii) complexes with polydentate N-heterocyclic carbenes: Synthesis, structural characterization and hydrosilylation catalysis
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The platinum(ii) complexes of multidentate N-heterocyclic carbenes, [Pt(L1)2Cl](PF6) (1, L1 = N-methyl-N-(2-pyrimidinyl) imidazolylidene), [Pt(L2)Cl](PF6) (2, L2 = N-butyl-N-(1,10- phenanthrolin-2-yl)imidazolylidene), [PtL
- Lu, Chunxin,Gu, Shaojin,Chen, Wanzhi,Qiu, Huayu
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experimental part
p. 4198 - 4204
(2010/07/09)
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- Highly selective dehydrogenative silylation of alkenes catalyzed by rhenium complexes
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Rhenium(I) complexes of type [ReBr2(L)(NO)(PR3) 2] (L = H2 (1), CH3CN (2), and ethylene (3); R = iPr (a) and cyclohexyl (Cy; b)) catalyze dehydrogenative silylation of alkenes in a highly selective ma
- Jiang, Yanfeng,Blacque, Olivier,Fox, Thomas,Freeh, Christian M.,Berke, Heinz
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experimental part
p. 2121 - 2128
(2009/09/30)
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- Platinum chloride/Xphos-catalyzed regioselective hydrosilylation of functionalized terminal arylalkynes
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Totally regioselective hydrosilylation of functionalized terminal arylalkynes was achieved using PtCl2 associated with the air-stable and bulky Xphos ligand with various silanes. Regardless of the electronic nature of the substituents on the ar
- Hamze, Abdallah,Provot, Olivier,Brion, Jean-Daniel,Alami, Mouad
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p. 2429 - 2431
(2008/09/20)
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- Xphos ligand and platinum catalysts: A versatile catalyst for the synthesis of functionalized β-(E)-vinylsilanes from terminal alkynes
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Hydrosilylation of functionalized terminal arylalkynes with a variety of silanes catalyzed by PtCl2 or PtO2 in the presence of the air-stable and bulky Xphos ligand was investigated. Regardless of the electronic nature (electron withdrawing or donating group) and the position (o, m, p) of the substituents on the aromatic ring, a single β-(E)-styrylsilanes was obtained in good to excellent yields. The regioselectivity of the H-Si bond addition was found to be governed by steric effects induced by the bulky Xphos ligand. A dramatic regioselectivity was also observed when functionalized terminal aliphatic alkynes were employed as a substrate and in these cases regioisomeric β-(E)-vinylsilanes were generated with excellent selectivity.
- Hamze, Abdallah,Provot, Olivier,Brion, Jean-Daniel,Alami, Mouad
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p. 2789 - 2797
(2008/12/20)
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- Selective synthesis of (E)-triethyl(2-arylethenyl)silane derivatives by reaction of aryl bromides with triethyl vinylsilane catalysed by a palladium-tetraphosphine complex
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Cis, cis, cis-1,2,3,4-tetrakis(diphenylphosphinomethyl)cyclopentane / 0.5 [PdCl(C3H5)]2 system catalyses the Heck reaction of vinylsilane derivatives with a range of aryl bromides with high ratio substrate/catalyst in good yields. The formation of mixtures of styrene, (E)-triethyl(2-arylethenyl)silane and triethyl(1-arylethenyl)silane derivatives was observed in some cases. Very high selectivities (up to 100%) in favour of the formation of (E)-triethyl(2-arylethenyl)silane derivatives were obtained in the presence of sodium acetate as base. With other bases such as potassium carbonate, the formation of large amounts of styrene derivatives was observed. The reaction tolerates several functions such as fluoro, trifluoromethyl, methoxy, dimethylamino, acetyl, formyl, benzoyl, carboxylate, nitro or nitrile. Moreover, turnover numbers up to 10,000 can be obtained for this reaction.
- Battace, Ahmed,Zair, Touriya,Doucet, Henri,Santelli, Maurice
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p. 3790 - 3802
(2007/10/03)
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- Reaction pathways of zirconocene-catalyzed silylation of alkenes with chlorosilanes
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Reaction pathways as well as stereochemistries and stoichiometries of zirconocene-catalyzed silylation of olefins with chlorosilanes in the presence of nBuMgCl were studied and discussed in detail. Rate determining steps were examined by kineti
- Terao, Jun,Jin, Yingshi,Torii, Kazushi,Kambe, Nobuaki
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p. 1301 - 1308
(2007/10/03)
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- A highly regio- and stereoselective transition metal-catalyzed hydrosilylation of terminal alkynes under ambient conditions of air, water, and room temperature
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A highly efficient and stereoselective hydrosilylation of terminal alkynes was developed at room temperature in air and water.
- Wu, Wei,Li, Chao-Jun
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p. 1668 - 1669
(2007/10/03)
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- Zirconocene-catalyzed silylation of alkenes with chlorosilanes
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Vinylsilanes and/or allylsilanes are formed upon silylation of terminal alkenes with R3SiCl in the presence of a Grignard reagent and a catalytic amount of [Cp2ZrCl2] [Eq. (a)]. The reaction also proceeds under mild condit
- Terao, Jun,Torii, Kazushi,Saito, Koyu,Kambe, Nobuaki,Baba, Akio,Sonoda, Noboru
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p. 2653 - 2656
(2007/10/03)
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- Completely selective synthesis of (E)-β-(triethylsilyl)styrenes by Fe3(CO)12-catalyzed reaction of styrenes with triethylsilane
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Using Fe3(CO)12 as the catalyst, the reaction of styrenes (C6H5CH=CH2, p-CH3C6H4CH=CH2, p-ClC6H4CH=CH2, and p-CH3OC6H4CH=CH2) with triethylsilane gave (E)-β-(triethylsilyl)styrenes (2a, (E)-C6H5CH=CHSiEt3; 2b, (E)-p-CH3C6H4CH=CHSiEt3; 2c, (E)-p-ClC6H4CH=C
- Kakiuchi, Fumitoshi,Tanaka, Yasuo,Chatani, Naoto,Murai, Shinji
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- Single-Operation Synthesis of Vinylsilanes from Alkenes and Hydrosilanes with the Aid of Ru3(CO)12
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Alkenes (RCH=CH2, where R = C6H5, p-CH3C6H4, p-CH3OC6H4, p-ClC6H4, 2-naphthyl, (CH3)3C, Me3SiO(CH3)2C, n-C4H9O, and Et3Si) with HSiEt3 with Ru3(CO)12 as a catalyst gave corresponding vinylsilanes (1, 6-13) without formation of simple addition products.Hydrosilanes such as HSiMe3, HSiEt2Me, HSiPhMe2, and HSi(OEt)3 also yielded vinylsilanes.Alkenes having a hydrogen atom at the allylic position (1-hexene, allylbenzene, 3-phenoxyprop-1-ene, vinylcyclohexane, β-methylstyrene, α-methylstyrene, 2-hexene) formed mixtures of vinylsilanes and allylsilanes.The ratio of vinylsilane 16 to allylsilane 17 decreased with an increase in temperature and with time.Substituted styrenes with a hydrosilane in the presence of 1-hexene gave vinylsilanes 1 and 6-8 in good yields based on the styrenes along with n-hexane.
- Seki, Yoshio,Takeshita, Kenji,Kawamoto, Kazuaki,Murai, Shinji,Sonoda, Noboru
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p. 3890 - 3895
(2007/10/02)
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