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Nobuaki Kambe - One of the best experts on this subject based on the ideXlab platform.
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Transition metal catalyzed carbon‐silicon bond forming reactions using Chlorosilanes promoted by Grignard reagents
Chemical record (New York N.Y.), 2007Co-Authors: Jun Terao, Nobuaki KambeAbstract:New catalytic C--Si bond-forming reactions using Chlorosilanes are described. These reactions proceed efficiently under mild conditions by the combined use of Grignard reagents and transition metal catalysts, such as Ti, Zr, Ni, and Pd. It is proposed that ate complex intermediates formed by the reaction of transition metals with Grignard reagents play important roles as the active catalytic species. The present study demonstrates the practical use of Chlorosilanes in transition metal catalyzed silylation reactions providing convenient methods for allyl- or vinylsilane synthesis. The reaction pathways of these transformations as well as the scope and limitations are discussed.
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transition metal catalyzed carbon silicon bond forming reactions using Chlorosilanes promoted by grignard reagents
Chemical Record, 2007Co-Authors: Jun Terao, Nobuaki KambeAbstract:New catalytic C--Si bond-forming reactions using Chlorosilanes are described. These reactions proceed efficiently under mild conditions by the combined use of Grignard reagents and transition metal catalysts, such as Ti, Zr, Ni, and Pd. It is proposed that ate complex intermediates formed by the reaction of transition metals with Grignard reagents play important roles as the active catalytic species. The present study demonstrates the practical use of Chlorosilanes in transition metal catalyzed silylation reactions providing convenient methods for allyl- or vinylsilane synthesis. The reaction pathways of these transformations as well as the scope and limitations are discussed.
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Pd-catalyzed Coupling Reaction of Allyl and Propargyl Ethers with Chlorosilanes
Chemistry Letters, 2007Co-Authors: Yoshitaka Naitoh, Jun Terao, Hitoshi Kuniyasu, Fumiaki Bando, Kazutaka Otsuki, Nobuaki KambeAbstract:Pd-catalyzed synthesis of allylsilanes from Chlorosilanes and allyl ethers is described. The reaction proceeds efficiently at room temperature by the use of phenyl or vinyl Grignard reagent in the ...
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Silylation and alkylation of allenes using Chlorosilanes and alkyl halides in the presence of palladium catalyst and Grignard reagents
Journal of Organometallic Chemistry, 2006Co-Authors: Yuuki Fujii, Jun Terao, Hitoshi Kuniyasu, Nobuaki KambeAbstract:Allenes react with Grignard reagents and Chlorosilanes in the presence of a palladium catalyst giving rise to carbosilylated products bearing carbon groups from Grignard reagents at the central carbon and silyl groups at the terminal carbon. When alkyl halides were used instead of Chlorosilanes, the corresponding alkylated products were obtained.
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Palladium-Catalyzed Dimerization Disilylation of 1,3-Butadiene with Chlorosilanes
Organic letters, 2004Co-Authors: Jun Terao, Akihiro Oda, Nobuaki KambeAbstract:[reaction: see text] 1,3-Butadiene reacted with Chlorosilanes and Grignard reagents at 20 degrees C in the presence of a catalytic amount of Pd(acac)(2) to give disilylated dimers 2 regioselectively, which have two silyl groups (R(3)Si) at the 3- and 8-positions of a 1,6-octadiene skeleton. When phenyl- or allyl-substituted Chlorosilanes were used, coupling product was obtained stereo- as well as regioselectively, giving rise to only (E)-olefins. It is proposed that Pd-ate complexes play important roles in both C-Si bond-forming processes.
Jun Terao - One of the best experts on this subject based on the ideXlab platform.
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Transition metal catalyzed carbon‐silicon bond forming reactions using Chlorosilanes promoted by Grignard reagents
Chemical record (New York N.Y.), 2007Co-Authors: Jun Terao, Nobuaki KambeAbstract:New catalytic C--Si bond-forming reactions using Chlorosilanes are described. These reactions proceed efficiently under mild conditions by the combined use of Grignard reagents and transition metal catalysts, such as Ti, Zr, Ni, and Pd. It is proposed that ate complex intermediates formed by the reaction of transition metals with Grignard reagents play important roles as the active catalytic species. The present study demonstrates the practical use of Chlorosilanes in transition metal catalyzed silylation reactions providing convenient methods for allyl- or vinylsilane synthesis. The reaction pathways of these transformations as well as the scope and limitations are discussed.
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transition metal catalyzed carbon silicon bond forming reactions using Chlorosilanes promoted by grignard reagents
Chemical Record, 2007Co-Authors: Jun Terao, Nobuaki KambeAbstract:New catalytic C--Si bond-forming reactions using Chlorosilanes are described. These reactions proceed efficiently under mild conditions by the combined use of Grignard reagents and transition metal catalysts, such as Ti, Zr, Ni, and Pd. It is proposed that ate complex intermediates formed by the reaction of transition metals with Grignard reagents play important roles as the active catalytic species. The present study demonstrates the practical use of Chlorosilanes in transition metal catalyzed silylation reactions providing convenient methods for allyl- or vinylsilane synthesis. The reaction pathways of these transformations as well as the scope and limitations are discussed.
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Pd-catalyzed Coupling Reaction of Allyl and Propargyl Ethers with Chlorosilanes
Chemistry Letters, 2007Co-Authors: Yoshitaka Naitoh, Jun Terao, Hitoshi Kuniyasu, Fumiaki Bando, Kazutaka Otsuki, Nobuaki KambeAbstract:Pd-catalyzed synthesis of allylsilanes from Chlorosilanes and allyl ethers is described. The reaction proceeds efficiently at room temperature by the use of phenyl or vinyl Grignard reagent in the ...
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Silylation and alkylation of allenes using Chlorosilanes and alkyl halides in the presence of palladium catalyst and Grignard reagents
Journal of Organometallic Chemistry, 2006Co-Authors: Yuuki Fujii, Jun Terao, Hitoshi Kuniyasu, Nobuaki KambeAbstract:Allenes react with Grignard reagents and Chlorosilanes in the presence of a palladium catalyst giving rise to carbosilylated products bearing carbon groups from Grignard reagents at the central carbon and silyl groups at the terminal carbon. When alkyl halides were used instead of Chlorosilanes, the corresponding alkylated products were obtained.
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Palladium-Catalyzed Dimerization Disilylation of 1,3-Butadiene with Chlorosilanes
Organic letters, 2004Co-Authors: Jun Terao, Akihiro Oda, Nobuaki KambeAbstract:[reaction: see text] 1,3-Butadiene reacted with Chlorosilanes and Grignard reagents at 20 degrees C in the presence of a catalytic amount of Pd(acac)(2) to give disilylated dimers 2 regioselectively, which have two silyl groups (R(3)Si) at the 3- and 8-positions of a 1,6-octadiene skeleton. When phenyl- or allyl-substituted Chlorosilanes were used, coupling product was obtained stereo- as well as regioselectively, giving rise to only (E)-olefins. It is proposed that Pd-ate complexes play important roles in both C-Si bond-forming processes.
Viatcheslav Jouikov - One of the best experts on this subject based on the ideXlab platform.
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Nucleophilic displacement versus electron transfer in the reactions of alkyl Chlorosilanes with electrogenerated aromatic anion radicals
Electrochimica Acta, 2015Co-Authors: Saida Soualmi, Mamadou Dieng, Ali Ourari, Diariatou Gningue-sall, Viatcheslav JouikovAbstract:Anion radicals of a series of aromatic compounds (C6H5CN, C6H5COOEt, anthracene, 9,10-dimethyl-, 9,10-diphenyl- and 9-phenylanthracene, pyrene and naphthalene) react with trialkyl Chlorosilanes R1R2R3SiCl (R1-3 = Me, Et; R1,2 = Me, R3 = t-Bu) in multiple ways, following classical bimolecular schemes. The ratio of one-electron transfer (ET) to a two-electron process (SN2-like nucleophilic attack of the reduced form of mediator on the chlorosilane, with k2 ≅ 102-108 M−1 s−1) is inversely related to the steric availability of Si for nucleophilic displacement reactions. The nucleophilic substitution pathway mainly results in mono- and disilylated aromatic products. Paralleling the electrochemical data with DFT calculations, the role of silicophilic solvent (DMF) in SN process was shown to be quite complex because of its involvement into coordination extension at silicon, dynamically modifying energetics of the process along the reaction coordinate. Although 2,2'-bipyridine also forms delocalized persistent anion radicals, they do not induce neither ET nor SN reactions in the same manner as aromatic mediators. Silicophilicity of 2,2'-bipyridine being superior to that of DMF, a R3SiCl·bipy complex of hypercoordinated silicon with electroactive ligand was formed instead, whose reduction requires about 1 V less negative potentials than bipyridine itself.
Richard A Register - One of the best experts on this subject based on the ideXlab platform.
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strategies for the synthesis of well defined star polymers by anionic polymerization with chlorosilane coupling and preservation of the star architecture during catalytic hydrogenation
Macromolecules, 2016Co-Authors: Adam B Burns, Richard A RegisterAbstract:The synthesis of isoprene-based star polymers by anionic polymerization, chlorosilane coupling, and catalytic hydrogenation was studied in detail, with the goal of obtaining and preserving a well-defined star architecture. The coupling reaction between polyisoprenyllithium (PI-Li) and Chlorosilanes, which can be intractably slow in apolar media, was dramatically accelerated by the concurrent addition of tetrahydrofuran (THF) with the coupling agent. In the presence of THF, PI-Li produces a yellow color allowing the living end concentration to be tracked visually, enabling near-stoichiometric coupling, as demonstrated by the synthesis of 6-arm star polymers and star block copolymers. Moreover, glassblowing techniques are not required. Star polymers coupled with chlorosilane terminating agents lost arms during catalytic hydrogenation. Several common hydrogenation catalysts were evaluated. The degree of degradation depended on the identity of the catalyst and the temperature of the reaction—more active catal...
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Strategies for the Synthesis of Well-Defined Star Polymers by Anionic Polymerization with Chlorosilane Coupling and Preservation of the Star Architecture during Catalytic Hydrogenation
2016Co-Authors: Adam B Burns, Richard A RegisterAbstract:The synthesis of isoprene-based star polymers by anionic polymerization, chlorosilane coupling, and catalytic hydrogenation was studied in detail, with the goal of obtaining and preserving a well-defined star architecture. The coupling reaction between polyisoprenyllithium (PI-Li) and Chlorosilanes, which can be intractably slow in apolar media, was dramatically accelerated by the concurrent addition of tetrahydrofuran (THF) with the coupling agent. In the presence of THF, PI-Li produces a yellow color allowing the living end concentration to be tracked visually, enabling near-stoichiometric coupling, as demonstrated by the synthesis of 6-arm star polymers and star block copolymers. Moreover, glassblowing techniques are not required. Star polymers coupled with chlorosilane terminating agents lost arms during catalytic hydrogenation. Several common hydrogenation catalysts were evaluated. The degree of degradation depended on the identity of the catalyst and the temperature of the reactionmore active catalysts and higher temperatures led to more scissionbut not the reaction time. Degradation closely tracked the hydrogenation reaction indicating that scission is a catalytically activated process. This phenomenon is attributed to a decreasing affinity of the polymer for the catalyst with increasing saturation. Degradation of the star architecture depended strongly on the steric environment at the core. It was shown that the steric strain can be reduced by tuning the topology of the coupling agent to limit the number of arms per Si atom. The steric constraints at the core were further relaxed by adding a short run of butadiene units to the arms just prior to coupling, which nearly eliminated degradation during hydrogenation of a 6-arm star
Bogdan Marciniec - One of the best experts on this subject based on the ideXlab platform.
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Iridium-Promoted Conversion of Chlorosilanes to Alkynyl Derivatives in a One-Pot Reaction Sequence
Organometallics, 2014Co-Authors: Ireneusz Kownacki, Bartosz Orwat, Bogdan MarciniecAbstract:By making use of the catalytic potential of the iridium system [{Ir(μ-Cl)(CO)2}2]/NEt(i-Pr)2 in the synthesis of silyl-functionalized alkynes via silylative coupling of terminal alkynes/diynes with iodosilanes, we propose a new protocol allowing employment of various mono- and diChlorosilanes as reagents. The process is based on a sequence of two reactions occurring simultaneously: i.e., conversion of initial chlorosilane (SiR1nCl4–n) to the appropriate iodosilane via Cl/I nucleophilic substitution and its further conversion to a silylalkyne derivative ((SiR1n(C≡CR2)4–n) via iridium-catalyzed silylative coupling with terminal alkyne. Under optimum conditions, the method has proved to be effective and versatile in the conversion of a wide range of Chlorosilanes to a rich portfolio of various corresponding alkynyl-functionalized silicon derivatives. Additionally, NMR studies of the equimolar reaction of a well-defined iridium(I) alkynyl precursor with Me3Si–I revealed that ≡Si–I bond activation in iodosilan...
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Iridium-Promoted Conversion of Chlorosilanes to Alkynyl Derivatives in a One-Pot Reaction Sequence
2014Co-Authors: Ireneusz Kownacki, Bartosz Orwat, Bogdan MarciniecAbstract:By making use of the catalytic potential of the iridium system [{Ir(μ-Cl)(CO)2}2]/NEt(i-Pr)2 in the synthesis of silyl-functionalized alkynes via silylative coupling of terminal alkynes/diynes with iodosilanes, we propose a new protocol allowing employment of various mono- and diChlorosilanes as reagents. The process is based on a sequence of two reactions occurring simultaneously: i.e., conversion of initial chlorosilane (SiR1nCl4–n) to the appropriate iodosilane via Cl/I nucleophilic substitution and its further conversion to a silylalkyne derivative ((SiR1n(CCR2)4–n) via iridium-catalyzed silylative coupling with terminal alkyne. Under optimum conditions, the method has proved to be effective and versatile in the conversion of a wide range of Chlorosilanes to a rich portfolio of various corresponding alkynyl-functionalized silicon derivatives. Additionally, NMR studies of the equimolar reaction of a well-defined iridium(I) alkynyl precursor with Me3Si–I revealed that Si–I bond activation in iodosilane molecules occurred via oxidative addition to the iridium center