- CATALYST AND RELATED METHODS INVOLVING HYDROSILYLATION AND DEHYDROGENATIVE SILYLATION
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A catalyst having a specific structure and a method fop rearing the catalyst is disclosed. A composition is also disclosed, which comprises: (A) an unsaturated compound including at least one aliphatically unsaturated group per molecule, subject to at least one of the following two provisos: (1) the (A) unsaturated compound also includes at least one silicon-bonded hydrogen atom per molecule; and/or (2) the composition further comprises (B) a silicon hydride compound including at least one silicon-bonded hydrogen atom per molecule. The composition further comprises (C) the catalyst. A method of preparing a hydrosilylation reaction product and a dehydrogenative silylation reaction product are also disclosed.
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Paragraph 00152-00154; 00157; 00160
(2019/02/06)
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- Fe and Co Complexes of Rigidly Planar Phosphino-Quinoline-Pyridine Ligands for Catalytic Hydrosilylation and Dehydrogenative Silylation
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Co and Fe dihalide complexes of a new rigidly planar PNN ligand platform are prepared and examined as precatalysts for hydrosilylation of alkenes. Lithiation of Thummel's 8-bromo-2-(pyrid-2′-yl)quinoline followed by treatment with (i-Pr)2PCl and (C6F5)2PCl afforded the phosphine-quinoline-pyridine ligands, abbreviated RPQpy for R = i-Pr and C6F5, respectively. These ligands form 1:1 adducts with the dichlorides and dibromides of iron and cobalt. Crystallographic characterization of FeBr2(iPrPQpy), FeBr2(ArFPQpy), CoCl2(iPrPQpy), CoBr2(iPrPQpy), and CoCl2(ArFPQpy) confirmed that the M-P-C-C-N-C-C-N portion of these complexes is planar within 0.078 ? unlike previous generations of PNN complexes where deviations from planarity were ~0.35 ?. Bond distances as well as magnetism indicate that the Fe complexes are high spin and the cobalt complexes are high spin or participate in spin equilibria. Also investigated were the NNN analogues of the RPQpy ligands, wherein the phosphine group was replaced by the mesityl ketimine. The complexes FeBr2(MesNQpy) and CoCl2(MesNQpy) were characterized crystallographically. Reduction of MX2(RPQpy) complexes with NaBHEt3 generates catalysts active for anti-Markovnikov silylation of simple and complex 1-alkenes with a variety of hydrosilanes. Catalysts derived from MesNQpy exhibited low activity. Fe-RPQpy derived catalysts favor hydrosilylation, whereas Co-RPQpy based catalysts favor dehydrogenative silylation. Catalysts derived from CoX2(iPrPQpy) convert hydrosilanes and ethylene to vinylsilanes. Related experiments were conducted on propylene to give propenylsilanes.
- Basu, Debashis,Gilbert-Wilson, Ryan,Gray, Danielle L.,Rauchfuss, Thomas B.,Dash, Aswini K.
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p. 2760 - 2768
(2018/09/10)
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- Thieme Chemistry Journals Awardees - Where Are They Now? Titanium-Catalyzed Hydroaminoalkylation of Vinylsilanes and a One-Pot Procedure for the Synthesis of 1,4-Benzoazasilines
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Vinylsilanes undergo intermolecular alkene hydroaminoalkylation with secondary amines in the presence of a titanium mono(aminopyridinato) catalyst to give the branched hydroaminoalkylation products with high regioselectivity. Corresponding reactions of a suitable (2-bromophenyl)vinylsilane combined with a subsequent intramolecular Buchwald-Hartwig amination result in the development of an elegant one-pot procedure for the synthesis of 1,4-benzoazasilines.
- Lühning, Lars H.,Rosien, Michael,Doye, Sven
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supporting information
p. 2489 - 2494
(2017/11/04)
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- Direct and selective arylation of tertiary silanes with rhodium catalyst
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(Chemical Equation Presented) We have developed a convenient and efficient approach to the arylation of tertiary silanes under mild conditions. A variety of arylsilanes were synthesized in a one-step process with good to excellent yields in the presence of a rhodium catalyst with a base. The reaction was highly solvent dependent, and amides were the most effective of the various solvents used. This common catalyst system is highly tolerant of the various sensitive functional groups on the substrates, which might be difficult to extract by other methods. The rhodium-promoted silylation of aryl halides with electron-donating groups occurred more efficiently than the silylation of aryl halides substituted with electron-withdrawing groups. Heteroaromatic halides were also found to be readily silylated with tertiary silanes. The successful application of this reaction to the synthesis of a TAC-101 analogue, which is a trialkylsilyl-containing synthetic retinoid benzoic acid derivative with selective binding affinity for retinoic acid receptor-α, is also described.
- Yamanoi, Yoshinori,Nishihara, Hiroshi
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p. 6671 - 6678
(2008/12/22)
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- Process for the preparation of vinyl- or allyl-containing compounds
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A vinyl- or allyl-containing compound represented by following Formula (3): wherein R2, R3, R4, R5, and R6 each represent hydrogen atom or a nonmetallic atom-containing group; R7 represents a nonmetallic atom-containing group; Y represents a group selected from the group consisting of —Si(R8) (R9) —, —Si(R10) (R11)—O—, the left hand of which is combined with R7, and —NR12—, wherein R8, R9, R10, R11, and R12 each represent hydrogen atom or a nonmetallic atom-containing group; and “n” represents 0 or 1, is prepared by reacting a vinyl or allyl ester compound represented by following Formula (1): wherein R1 represents hydrogen atom or a nonmetallic atom-containing group; R2, R3, R4, R5, R6, and “n” are as defined above, with a compound represented by following Formula (2): [in-line-formulae]R7—Y—H ??(2)[/in-line-formulae] wherein R7 and Y are as defined above, in the presence of a transition element compound.
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Page/Page column 6
(2008/06/13)
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- Titanocene-mediated homolytic opening of epoxysilanes
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The titanocene(III) chloride mediated opening of silyloxiranes has been examined. Electron transfer from the metal leads to α-silyl radicals with total regiocontrol. The radicals could be trapped by various olefins, and the corresponding adducts were obtained in good yields (Table). Further substitution of the oxirane by alkyl groups proved detrimental to the reactions, but ring opening remained essentially regioselective.
- Puljic, Nicolas,Albert, Matthias,Dhimane, Anne-Lise,Fensterbank, Louis,Lacote, Emmanuel,Malacria, Max
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p. 2297 - 2305
(2007/10/03)
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- Investigating the kinetics of homogeneous hydrogenation reactions using PHIP NMR spectroscopy
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The combination of parahydrogen induced polarization (PHIP), kinetics and NMR spectroscopy yields a powerful analytical tool: quantitative in situ NMR spectroscopy. Two versions of PHIP NMR experiments are presented to investigate the kinetics of homogeneously catalyzed hydrogenations. The first method, an experimental variation of the ROCHESTER experiment (ROCHESTER = rates of catalytic hydrogenation estimated spectroscopically through enhanced resonances), allows one to determine the hydrogenation rate independently of relaxation and other sources of decay, e.g., subsequent chemical reaction steps. The second method named DYPAS (dynamic PASADENA spectroscopy) uses a variable delay between the end of the hydrogen-addition period and the detection pulse. In principle, all processes during this delay can be described by a set of coupled differential equations. Their solutions can be fitted to the experimental data by a least-squares optimization of the involved kinetic parameters. The DYPAS method can be used to determine the rates of formation as well as the rates of decomposition of stable intermediates and has been applied to the case of freshly hydrogenated and still catalyst-attached product molecules. We provide kinetic data for the formation and decomposition of these unusual product-catalyst complexes during the hydrogenation of different styrene derivatives with a cationic Rh1 catalyst containing a chelating diphosphine ligand. The kinetic measurements indicate that the rate of formation of the catalyst-attached product increases whereas the rate constant of its decomposition diminishes if the para position of the arene ring of styrene carries an electron- donating substituent. In the case of p-aminostyrene as the substrate, the detachment step turned out to be rate limiting for the catalytic cycle. With certain substituted styrenes and cationic Rh1 complexes containing chiral chelating diphosphine ligands, two geometrically different (diastereomeric) product-catalyst adducts can be discriminated via PHIP NMR spectroscopy. The associated alternative reaction pathways have been analyzed by applying the DYPAS method, which can also be used to investigate the mechanism of an asymmetric hydrogenation.
- Hübler, Patrick,Giernoth, Ralf,Kümmerle, Günther,Bargon, Joachim
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p. 5311 - 5318
(2007/10/03)
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- Addition of sulphenyl halides to alkenyl-metal compounds III. Arenesulphenyl chloride additions to triethoxy- and triphenylvinylsilanes and to triphenylvinylgermanium. Crystal structure of (4-Me-2-O2NC6H3S)CH(SiPh3)CH2Cl
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Additions of arenesulphenyl chlorides (e.g.ArSCl=p-XC6H4SCl; X=Me or Cl; 4-Y-2-O2NC6H4SCl; Y=H, Me or NO2) to R3MCH=CH2 can provide both possible adducts: R3MCHSArCH2Cl (the anti-Markovnikov adducts) and R3MCHClCH2SAr (the Markovnikov adducts).In reactions in CH2Cl2 at room temperature, the former adducts always dominate (>77percent) and can be the exclusive products.The ratio of : increases in the sequences Ar=p-ClC6H4 > o-O2NC6H4 > 2,4-(O2N)2C6H3; (Me3SiCH=CH2) > Ph3SiCH=CH2 > (EtO)3SiCH=CH2; and Ph3SiCH=CH2 > Ph3GeCH=CH2.A crystal structure determination of (4-Me-2-O2NC6H3S)CH(SiPh3)CH2Cl revealed a slightly distorted tetrahedral geometry about Si with a staggered conformation about the central C-C bond (Si-C-C-Cl dihedral angle is 167 deg).There is a short S...O intramolecular distance of 2.781 Angstroem.
- Howie, R. Alan,Spencer, Gavin M.,Wardell, James L.
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p. 111 - 125
(2007/10/02)
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- FORMATION OF ALKYLATED TRIPHENYLSILYLALKENES FROM THE REACTION OF TRIPHENYLSILYL-SUBSTITUTED OXIRANYL ANION WITH ORGANOALUMINIUM REAGENTS
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Oxiranyl anion generated from 2-methyl-3-triphenylsilyloxirane and sec-BuLi gave (E)-2-triphenylsilyl-2-butene or (E,E)-3-triphenylsilyl-2,4-nonadiene upon treatment with trimethylaluminium or (E)-1-hexenyldiisobutylaluminium.
- Taniguchi, Masahiko,Oshima, Koichiro,Utimoto, Kiitiro
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p. 2783 - 2786
(2007/10/02)
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