- Ga+-catalyzed hydrosilylation? about the surprising system Ga+/HSiR3/olefin, proof of oxidation with subvalent Ga+and silylium catalysis with perfluoroalkoxyaluminate anions
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Already 1 mol% of subvalent [Ga(PhF)2]+[pf]- ([pf]- = [Al(ORF)4]-, RF = C(CF3)3) initiates the hydrosilylation of olefinic double bonds under mild conditions. Reactions with HSiMe3 and HSiEt3 as substrates efficiently yield anti-Markovnikov and anti-addit
- Barthélemy, Antoine,Glootz, Kim,Hanske, Annaleah,Krossing, Ingo,Scherer, Harald
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p. 439 - 453
(2022/01/22)
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- METHOD FOR PRODUCING ARYLSILANE COMPOUND CONTAINING HALOSILANE COMPOUND AS RAW MATERIAL
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PROBLEM TO BE SOLVED: To provide a method for producing an arylsilane compound with low production cost. SOLUTION: A method for producing an arylsilane compound includes a reaction step for the cross-coupling reaction of a halosilane compound represented by general formula (A-1), (A-2), or (A-3) and an arylboronic acid pinacol ester in the presence of a nickel catalyst, a Lewis acid catalyst, and an organic base (R independently represent an aromatic hydrocarbon group, a heteroaromatic ring group, or a C1-20 hydrocarbon group; X independently represent a halogeno group or a trifluoromethanesulfonyloxy group). SELECTED DRAWING: None COPYRIGHT: (C)2020,JPOandINPIT
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Paragraph 0057
(2020/03/06)
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- Silylpalladium Cations Enable the Oxidative Addition of C(sp3)-O Bonds
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The synthesis and characterization of the room-temperature and solution-stable silylpalladium cations (PCy3)2Pd-SiR3+(C6F5)4B- (SiR3 = SiMe2Et, SiHEt2) and (Xantphos)Pd-SiR3+(BArf4) (SiR3 = SiMe2Et, SiHEt2; Xantphos = 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene; BArf4 = (3,5-(CF3)2C6H3)4B-) are reported. Spectroscopic and ligand addition experiments suggest that silylpalladium complexes of the type (PCy3)2Pd-SiR3+ are three-coordinate and T-shaped. Addition of dialkyl ethers to both the PCy3 and Xantphos-based silylpalladium cations resulted in the cleavage of C(sp3)-O bonds and the generation of cationic Pd-alkyl complexes. Mechanistically enabling is the ability of silylpalladium cations to behave as sources of both electrophilic silylium ions and nucleophilic LnPd(0).
- Wierschen, Andreas L.,Romano, Neyen,Lee, Stephen J.,Gagné, Michel R.
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supporting information
p. 16024 - 16032
(2019/11/11)
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- Wagner-Meerwein-Type Rearrangements of Germapolysilanes - A Stable Ion Study
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(Chemical Equation Presented). The rearrangement of tris(trimethylsilyl)silyltrimethylgermane 1 to give tetrakis(trimethylsilyl)germane 2 was investigated as a typical example for Lewis acid catalyzed Wagner-Meerwein-type rearrangements of polysilanes and polygermasilanes. Direct 29Si NMR spectroscopic evidence is provided for several cationic intermediates during the reaction. The identity of these species was verified by independent synthesis and NMR characterization, and their transformation was followed by NMR spectroscopy.
- Albers, Lena,Meshgi, Mohammad Aghazadeh,Baumgartner, Judith,Marschner, Christoph,Müller, Thomas
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supporting information
p. 3756 - 3763
(2015/08/19)
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- Elongated Gilman cuprates: The key to different reactivities of cyano- and iodocuprates
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In the past the long-standing and very controversial discussion about a special reactivity of cyano- versus iodocuprates concentrated on the existence of higher-order cuprate structures. Later on numerous structural investigations proved the structural equivalence of iodo and cyano Gilman cuprates and their subsequential intermediates. For dimethylcuprates similar reactivities were also shown. However, the reports about higher reactivities of cyanocuprates survived obstinately in many synthetic working groups. In this study we present an alternative structural difference between cyano- and iodocuprates, which is in agreement with the results of both sides. The key is the potential incorporation of alkyl copper in iodo but not in cyano Gilman cuprates during the reaction. In the example of cuprates with a highly soluble substituent (R = Me 3SiCH2) we show that in the case of iodocuprates during the reaction several copper-rich complexes are formed, which consume additional iodocuprate and provide lower reactivities. To confirm this, a variety of highly soluble copper-rich complexes were synthesized, and their molecular formulas, the position of the equilibriums, their monomers and their aggregation trends were investigated by NMR spectroscopic methods revealing extended iodo Gilman cuprates. In addition, the effect of these copper-rich complexes on the yields of cross-coupling reactions with an alkyl halide was tested, resulting in reduced yields for iodocuprates. Thus, this study gives an explanation for the thus far confusing results of both similar and different reactivities of cyano- and iodocuprates. In the case of small substituents the produced alkyl copper precipitates and similar reactivities are observed. However, iodocuprates with large substituents are able to incorporate alkyl copper units. The resulting copper-rich species have less polarized alkyl groups, i.e. gradually reduced reactivities.
- Neumeier, Maria,Gschwind, Ruth M.
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p. 5765 - 5772
(2014/05/06)
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- Recyclable self-assembly-supported catalyst for chelation-assisted hydroacylation of an olefin with a primary alcohol
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A novel recyclable catalyst for chelation-assisted hydroacylation of an olefin with a primary alcohol was developed by utilizing a hydrogen-bonding self-assembly motif consisting of a barbiturate bearing 2-aminopyridin-4-yl group and 5-hexyl-2,4,6-triaminopyrimidine. This was further applied to a mixed catalyst system to recycle both organic and organometallic catalysts.
- Kim, Do-Won,Lim, Sung-Gon,Jun, Chul-Ho
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p. 2937 - 2940
(2007/10/03)
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- Catalysis of hydrosilylation: Part XXXIV. High catalytic efficiency of the nickel equivalent of Karstedt catalyst [{Ni(η-CH2=CHSiMe2)2O} 2{μ-(η-CH2=CHSiMe2)2O}]
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The nickel equivalent of Karstedt catalyst [{Ni(η-CH2=CHSiMe2)2O} 2{μ-(η-CH2=CHSiMe2)2O}] (1) appeared to be a very efficient catalyst for dehydrogenative coupling of vinyl derivatives (styrene, vinylsilanes, vinylsiloxanes) with trisubstituted silanes HSi(OEt)3, HSiMe2Ph. The reaction occurs via three pathways of dehydrogenative coupling, involving formation of an unsaturated compound as the main product as well as a hydrogenated olefin (DS-1) pathway, hydrogenated dimeric olefin (DS-2) and dihydrogen (DC), respectively. The reaction is accompanied by side hydrosilylation. Stoichiometric reactions of 1 with styrene and triethoxysilane, in particular synthesis of the bis(triethoxysilyl) (divinyltetramethyldisiloxane) nickel complex 3 and the first documented insertion of olefin (styrene) into Ni-Si bond of complex 3, as well as all catalytic data have allowed us to propose a scheme of catalysis of this complex reaction by 1.
- Maciejewski,Marciniec,Kownacki
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p. 175 - 181
(2007/10/03)
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- Conversion of Vinylsilanes in the Presence of Triethoxysilane Catalyzed by Ruthenium Complexes
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Reaction of vinylsilanes with triethoxysilane catalyzed by ruthenium phosphine and non-phosphine complexes proceed via several competitive-consecutive routes including hydrosilylation, metathesis, hydrogenation and dehydrogenative silylation as well as migration and oxygenation of silyl groups, ethene hydrosilylation and catalytic redistribution of triethoxysilane.Ruthenium hydride and/or ruthenium silyl complexes seem to play the role of key intermediates in all the processes mentioned above.Key words: ruthenium complexes, silyl complexes, hydride complexes, competitive-consecutive reaction
- Gulinski, J.
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p. 1266 - 1272
(2007/10/02)
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- Competitive-consecutive reaction of vinyltrimethylsilane with triethylsilane catalyzed by ruthenium complexes
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A complex reaction of vinyltrimethylsilane with triethylsilane catalyzed by ruthenium carbonyl and ruthenium phosphine complexes and performed at 80-130 degC in air or oxygen-free conditions was followed by GC-MS.Catalytic examinations and identification of the products (I-X) allowed us to propose a general scheme for the competitive-consecutive reaction in which the complexes containing Ru-H and Ru-Si bonds play the role of key intermediates. ruthenium complex / dehydrogenative silylation / metathesis / vinyltrimethylsilane / triethylsilane
- Gulinski, Jacek,Pietraszuk, Cezary,Marciniec, Bogdan,Maciejewski, Hieronim
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p. 609 - 614
(2007/10/02)
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- Thiazine and thiazepine containing compounds
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This invention is directed to compounds of the formula STR1 wherein X is a thiazine or thiazepine of the formula STR2 These compounds possess angiotensin converting enzyme inhibition activity and are thus useful as hypotensive agents.
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- NOUVELLES UTILISATIONS DU TETRAMETHYLSILANE COMME AGENT DE METHYLATION DES CHLOROSILANES; VALORISATION DU METHYLTRICHLOROSILANE
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In the presence of catalytic amounts of AlCl3, the chlorosilanes MeSiCl3, ClMe2SiCH2Cl and PhSiCl3 convert Me4Si into Me3SiCl.In the first case, at 130 deg C, two by-products from the industrial synthesis of Me2SiCl2 provide the useful Me3SiCl as the unique product with a 44percent conversion ratio from Me4Si.From ClMe2SiCH2CL, the only products formed are Me3SiCl and Me3SiCH2Cl, which is a useful reagent for organic syntheses (formation ratio: 32percent), if the reaction is performed under atmospheric pressure, but if an autoclave is used EtMe2SiCl (88percent maximal yield) is obtained.
- Bordeau, M.,Djamei, S. M.,Calas, R.,Dunogues, J.
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p. 131 - 138
(2007/10/02)
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- Reduction of Halosilanes by Organotin Hydrides
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A study of the reduction of halosilanes with organotin hydrides is described.The free radical chain mechanism indicated by the results obtained parallels that known for the comparable reduction of haloalkanes, but the reactivity of α-haloalkanes is considerable enhanced.Mechanistic studies suggest that the polar nature of the halogen abstraction step in the radical chain sequence, which places incremental negative charge adjacent to silicon, is the principal reason for this enhanced reactivity.Structure-reactivity studies indicat the gem-dimethylsilyl function to be an electronic transmitter.The ρ values for reduction of aryldimethyl(chloromethyl)silanes and substituted benzyl chlorides by tri-n-butyltin hydride are essentially identical (+0.45).Reduction of (chloromethyl)trimethylsiulane with aryldimethyltin hydrides, conversely, yielded a ρ value of -1.61.The reduction produced racemic product from an optically active α-chlorosilane, the synthesis of which appears to the first reported.Other syntheses of variuos halosilanes of interest are also described.The title reduction is specific for carbon-halogen bonds.Silicon-halogen bonds are not affected, a distinction that should make the reduction synthetically useful.Because the increased reactivity of α-halosilanes in the reduction has thus been ascribed to a kinetic polar effect in a critical step of the mechanism, no compelling argument for special thermodynamic stability in α-silyl radicals themselves can be made.
- Wilt, James W.,Belmonte, Frank G.,Zieske, Paul A.
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p. 5665 - 5675
(2007/10/02)
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