- Iron-Catalyzed H/D Exchange of Primary Silanes, Secondary Silanes, and Tertiary Siloxanes
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A synthetic study into the catalytic hydrogen/deuterium (H/D) exchange of 1° silanes, 2° silanes, and 3° siloxanes is presented, facilitated by iron-β-diketiminato complexes (1a and 1b). Near-complete H/D exchange is observed for a variety of aryl- and alkyl-containing hydrosilanes and hydrosiloxanes. The reaction tolerates alternative hydride source pinacolborane (HBpin), with quantitative H/D exchange. A synthetic and density functional theory (DFT) investigation suggests that a monomeric iron-deuteride is responsible for the H/D exchange.
- Grayson, Matthew N.,Linford-Wood, Thomas G.,Mahon, Mary F.,Webster, Ruth L.
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p. 2979 - 2985
(2022/03/03)
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- Catalytic Enantioselective Dehydrogenative Si-O Coupling to Access Chiroptical Silicon-Stereogenic Siloxanes and Alkoxysilanes
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A rhodium-catalyzed enantioselective construction of triorgano-substituted silicon-stereogenic siloxanes and alkoxysilanes is developed. This process undergoes a direct intermolecular dehydrogenative Si-O coupling between dihydrosilanes with silanols or alocohols, giving access to a variety of highly functionalized chiral siloxanes and alkoxysilanes in decent yields with excellent stereocontrol, that significantly expand the chemical space of the silicon-centered chiral molecules. Further utility of this process was illustrated by the construction of CPL-active (circularly polarized luminescence) silicon-stereogenic alkoxysilane small organic molecules. Optically pure bis-alkoxysilane containing two silicon-stereogenic centers and three pyrene groups displayed a remarkable glum value with a high fluorescence quantum efficiency (glum = 0.011, φF = 0.55), which could have great potential application prospects in chiral organic optoelectronic materials.
- Zhu, Jiefeng,Chen, Shuyou,He, Chuan
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supporting information
p. 5301 - 5307
(2021/05/04)
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- PROCESS FOR THE STEPWISE SYNTHESIS OF SILAHYDROCARBONS
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The invention relates to a process for the stepwise synthesis of silahydrocarbons bearing up to four different organyl substituents at the silicon atom, wherein the process includes at least one step a) of producing a bifunctional hydridochlorosilane by a redistribution reaction, selective chlorination of hydridosilanes with an ether/HCI reagent, or by selective chlorination of hydridosilanes with SiCI4, at least one step b) of submitting a bifunctional hydridochloromonosilane to a hydrosilylation reaction, at least one step c) of hydrogenation of a chloromonosilane, and a step d) in which a silahydrocarbon compound is obtained in a hydrosilylation reaction.
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Page/Page column 54; 57
(2021/12/08)
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- Catalytic oxidation of diorganosilanes to 1,1,3,3-tetraorganodisiloxanes with gold nanoparticle assembly at the water-chloroform interface
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The formation of the spherical self-assembly of gold nanoparticles (AuNPs) of 200 ± 20 nm size at the water-chloroform interface is achieved by employing the cyclotetrasiloxane [RSCH2CH2SiMeO]4 (R = CH2CH2OH) as the stabilizing ligand. The interfacially stabilized AuNPs act as a versatile catalyst for selective hydrolytic oxidation of only one of the Si-H bonds in secondary organosilanes, RR1SiH2 (R, R1 = alkyl, aryl, and sila-alkyl), to afford the high yield synthesis of 1,1,3,3-tetraorganodisiloxanes, (HRR1Si)2O. The study unravels for the first time the role of the photothermal effect arising from the excitation of the surface plasmon resonance of the AuNPs under visible light irradiation in enhancing the catalytic activity at ambient temperature.
- Shankar, Ravi,Sharma, Asmita,Jangir, Bhawana,Chaudhary, Manchal,Kociok-K?hn, Gabriele
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p. 813 - 819
(2019/01/09)
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- Catalytic Reduction of Alkoxysilanes with Borane Using a Metallocene-Type Yttrium Complex
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The catalytic reduction of alkoxysilanes with the borane HBpin (pin = pinacolato) was achieved using a metallocene-type yttrium complex as a catalyst precursor. Mechanistic study supported the pivotal role of the rigid metallocene structure of the catalyst, which bears two bulky n5-C5Me4SiMe3 ligands, in suppressing the coordination of the side product MeOBpin that is generated during the reaction.
- Aoyagi, Keiya,Matsumoto, Kazuhiro,Shimada, Shigeru,Sato, Kazuhiko,Nakajima, Yumiko
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supporting information
p. 210 - 212
(2019/02/01)
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- MANUFACTURING METHOD OF HYDROSILANE
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PROBLEM TO BE SOLVED: To provide a manufacturing method of hydrosilane capable of manufacturing hydrosilane at good efficiency. SOLUTION: Hydrosilane having a structure represented by the following formula (b) can be manufactured at good efficiency by reacting borohydride and hydrocarbon having a halogen atom and 1 to 20 carbon atoms, and/or a metal salt and further reacting the reaction product with alkoxysilane having a structure represented by the following formula (a) in the presence of triamide phosphate. In the formula (a), R represents a hydrocarbon group having 1 to 20 carbon atoms. SELECTED DRAWING: None COPYRIGHT: (C)2019,JPOandINPIT
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Paragraph 0037-0038
(2019/07/13)
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- Synthesis of hydrosilanes: Via Lewis-base-catalysed reduction of alkoxy silanes with NaBH4
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Hydrosilanes were synthesized by reduction of alkoxy silanes with BH3 in the presence of hexamethylphosphoric triamide (HMPA) as a Lewis-base catalyst. The reaction was also achieved using an inexpensive and easily handled hydride source NaBH4, which reacted with EtBr as a sacrificial reagent to form BH3in situ.
- Aoyagi, Keiya,Ohmori, Yu,Inomata, Koya,Matsumoto, Kazuhiro,Shimada, Shigeru,Sato, Kazuhiko,Nakajima, Yumiko
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supporting information
p. 5859 - 5862
(2019/05/27)
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- Organometallic Complexes of Bulky, Optically Active, C 3-Symmetric Tris(4 S -isopropyl-5,5-dimethyl-2-oxazolinyl)phenylborate (ToP)
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A bulky, optically active monoanionic scorpionate ligand, tris(4S-isopropyl-5,5-dimethyl-2-oxazolinyl)phenylborate (ToP), is synthesized from the naturally occurring amino acid l-valine as its lithium salt, Li[ToP] (1). That compound is readily converted to the thallium complex Tl[ToP] (2) and to the acid derivative H[ToP] (3). Group 7 tricarbonyl complexes ToPM(CO)3 (M = Mn (4), Re (5)) are synthesized by the reaction of MBr(CO)5 and Li[ToP] and are crystallographically characterized. The νCO bands in their infrared spectra indicate that π back-donation in the rhenium compounds is greater with ToP than with non-methylated tris(4S-isopropyl-2-oxazolinyl)phenylborate (ToP). The reaction of H[ToP] and ZnEt2 gives ToPZnEt (6), while ToPZnCl (7) is synthesized from Li[ToP] and ZnCl2. The reaction of ToPZnCl and KOtBu followed by addition of PhSiH3 provides the zinc hydride complex ToPZnH (8). Compound 8 is the first example of a crystallographically characterized optically active zinc hydride. We tested its catalytic reactivity in the cross-dehydrocoupling of silanes and alcohols, which provided Si-chiral silanes with moderate enantioselectivity (Chemical Equation).
- Xu, Songchen,Magoon, Yitzhak,Reinig, Regina R.,Schmidt, Bradley M.,Ellern, Arkady,Sadow, Aaron D.
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p. 3508 - 3519
(2015/08/06)
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- Activation of N-heterocyclic carbenes by {BeH2} and {Be(H)(Me)} fragments
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A stable three-coordinate dimethylberyllium species coordinated by the 1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene (IMes) ligand is readily converted to the corresponding methylhydrido derivative through metathetical reaction with phenylsilane. Attempts to synthesize the corresponding molecular dihydrides are, however, unsuccessful and result in ring opening of an IMes ligand through hydride transfer to the donor carbon atom and the consequent formation of a heterocyclic beryllium organoamide. In agreement with previous calculations, we suggest that this process occurs via a Schlenk-type equilibration process and formation of a four-coordinate bis-NHC beryllium dihydride. These species are not observed, however, as the steric pressure exerted by coordination of the two sterically demanding IMes ligands is sufficient to induce hydride transfer. The latter deduction is supported by the observation that a similar ring-opened product, but derived from methyl and hydride transfer, is available through the introduction of a further equivalent of IMes to the isolated beryllium methyl hydride species. In the latter case the ring-opening process is more facile, which we ascribe to the increased steric pressure achieved upon the formation of four-coordinate beryllium. In a further striking reaction under more forcing thermal conditions, the carbene carbon center of an IMes ligand is observed to be completely eliminated with selective formation of a three-coordinate diamidoberyllium species.
- Arrowsmith, Merle,Hill, Michael S.,Kociok-K??hn, Gabriele
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p. 653 - 662
(2015/03/05)
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- Magnesium-catalyzed hydrosilylation of α,β-unsaturated esters
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ToMMgHB(C6F5)3 (1, ToM = tris(4,4-dimethyl-2-oxazolinyl)phenylborate) catalyzes the 1,4-hydrosilylation of α,β-unsaturated esters. This magnesium hydridoborate compound is synthesized by the reaction of ToMMgMe, PhSiH3, and B(C6F5)3. Unlike the transient ToMMgH formed from the reaction of ToMMgMe and PhSiH3, the borate adduct 1 persists in solution and in the solid state. Crystallographic characterization reveals tripodal coordination of the HB(C6F5)3 moiety to the six-coordinate magnesium center with a ∠Mg-H-B of 141(3)°. The pathway for formation of 1 is proposed to involve the reaction of ToMMgMe and a PhSiH3/B(C6F5)3 adduct because the other possible intermediates, ToMMgH and ToMMgMeB(C6F5)3, react to give an intractable black solid and ToMMgC6F5, respectively. Under catalytic conditions, silyl ketene acetals are isolated in high yield from the addition of hydrosilanes to α,β-unsaturated esters with 1 as the catalyst.
- Lampland, Nicole L.,Pindwal, Aradhana,Neal, Steven R.,Schlauderaff, Shealyn,Ellern, Arkady,Sadow, Aaron D.
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p. 6901 - 6907
(2015/11/23)
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- Titanocene(III) catalyzed homogeneous hydrosilation-hydrogenation of pyridines
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The homogeneous catalytic hydrosilation-hydrogenation of pyridines is observed in the presence of Cp2TiMe2 (Cp = η5-C5H5) and CpCp*TiMe2 (Cp* = η5-C5Me5) as catalysts and using PhSiH3 or PhMeSiH2 as the source of Si-H. Under appropriate conditions, and with appropriate ring-substitution, good yields of the N-silyldihydropyridine or N-silyltetrahydropyridine products are be obtained. Although complete saturation is not achieved with organosilane alone, carrying out the reaction under moderate H2 pressures can give excellent yields of N-silylpiperidines. Under moderate pressures of H2, [Cp2TiH]2 catalyzes rapid H-D exchange between H2 and the 2- and 6-positions of C5D5N. Under the same conditions, only traces of hydrogenation are observed. This, together with the regioselectivity of 3-picoline hydrosilation-hydrogenation, leads to the conclusion that the key step in the reaction is probably addition of Ti-Si to C=N.
- Harrod,Shu,Woo,Samuel
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p. 1075 - 1085
(2007/10/03)
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- Redistribution of dichlorosilanes and dihydridosilanes. Synthesis of chloro hydridosilanes
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The redistribution of dichlorosilanes RSi(CH3)Cl2 and dihydridosilanes RSi(CH3)H2, prepared by reduction of the homologues dichlorosilanes, in the presence of a quaternary ammonium salt is presented. The influence of the nature of R (fluoroalkyl chain RFCH2CH2 with RF = CF3, C4F9, C8F17, alkyl chain R = C6H13 or aromatic R = C6H5) and of the temperature on the rate of the reaction is studied. The equilibrium constants and free enthalpies are calculated and discussed taking into account the nature of R. The new products described were characterized from I.R, 1H, 19F and 29Si NMR spectroscopies.
- Benouargha,Boulahia,Boutevin,Caporiccio,Guida-Pietrasanta,Ratsimihety
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- Reactions of symmetrical and unsymmetrical disilanes in the presence of Cp2MCl2/nBuli ( M = Ti, Zr, Hf)
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The reactions of disilanes with catalytic quantities of Cp2MCl2/n BuLi (M = Ti, Zr) and cis-cyclooctene in a disilane/cyclooctene/metal ratio of approximately 30 : ≥ 30: 1 exhibited rapid formation of monosilanes and trisilanes. The product distributions produced from H(PhMeSi)2H, H(BuMeSi)2H (symmetrical disilanes) and from HPh2SiSiPhMeH, HPhMeSiSiMe2H, HPhMeSiSiPrMeH and HPh2SiSiPhH2 (unsymmetrical disilanes) were determined by GCMS in all cases and the trisilanes from HPh2SiSiPhMeH and HPhMeSiSiMe2 H were isolated and characterized spectroscopically. Major and minor isomers of Ph4Me2Si3H2 and Ph5MeSi3H2 (formed from HPh2SiSiPhMeH) and of PhMe5Si3H2 and Ph2Me4Si3H2 (formed from HPhMeSiSiMe2H) were identified. Analysis of the product distribution in these reactions indicated that both Si-Si bond cleavage and Si-H dehydrocoupling of the starting disilane occurs. Rationalization of the product distributions and apparent isomer preferences through both σ-bond metathesis steps and metal silylene intermediates is presented. The rapid reaction of the Si-Si bond in H(SiPhMe)χH was found to be characteristic of the disilane and occurred only to a minor extent in the trisilane and was absent in the tetrasilane.
- Corey,Rooney
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- SYNTHESIS OF AMINOTITANOSILOXANES
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Two methods for the synthesis of aminotitanosiloxanes based on hydrosilylation were developed, differing in the order of addition of allyl derivatives to dihydrosilanes.
- Khonina, T. G.,Podol'skii, A. V.,Suvorov, A. L.
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p. 2513 - 2518
(2007/10/02)
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- Reactivity of Hypervalent Species: Reactions of Anionic Penta-Coordinated Silicon Complexes towards Nucleophiles
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The reactivity of anionic penta-coordinated silicon complexes 4-O)2>-Na+ 1 with nucleophilic reagents has been studied. 1 can be reduced to organosilanes RSiH3 by metallic hydrides.Reactions with an excess of Grignard or organolithium reagents (R'MgX or R'Li) gave tetraorganosilanes RSiR'3.When only two molar equivalents of Grignard reagents (R'MgX) or lithium reagents (R'Li) are added to complexs 1 functional silanes RR'2SiX can be prepared.
- Boudin, Alain,Cerveau, Genevieve,Chuit, Claude,Corriu, Robert J. P.
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p. 101 - 106
(2007/10/02)
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