- A One-Step Germole to Silole Transformation and a Stable Isomer of a Disilabenzene
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An unusual germole-to-silole transformation is described. As key intermediates hetero-fulvenes are formed which rearrange to more stable bicyclic carbene analogues. The so-formed germylenes undergo a reductive elimination yielding elemental germanium and siloles. In contrast, the analogous silylenes are stable at ambient conditions and were identified by MS spectrometry and NMR spectroscopy supported by the results of quantum mechanical calculations. These bicyclic silylenes are stable derivatives of the global minimum of the C4Si2H6 potential energy surface.
- Reinhold, Crispin R. W.,Dong, Zhaowen,Winkler, Jan M.,Steinert, Henning,Schmidtmann, Marc,Müller, Thomas
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- Silicon-carbon unsaturated compounds. XLVIII. Synthesis and reactions of silicon analogs of lithium enolates
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The reaction of mesitoyl- and (2-methylbenzoyl)tris(trimethylsilyl)silane with 1 equiv. of a silyllithium gave silicon analogs of lithium enolates.Hydrolysis of the lithium silenolates afforded hydrosilanes in high yields.The lithium silenolates can be readily transformed into silenes quantitatively, by treatment with a chlorosilane. Key words: Silicon; Lithium; Unsaturated compounds; Lithium enolates
- Ohshita, Joji,Masaoka, Yoshiteru,Masaoka, Shin,Ishikawa, Mitsuo,Tachibana, Akitomo,et al.
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- TRIS(TRIMETHYLSILYL)SILYLLITHIUM *3 THF: A STABLE CRYSTALLINE SILYLLITHIUM REAGENT
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A synthesis of crystalline tris(trimethylsilyl)silyllithium * 3 THF is described.This stable compound can be used in hydrocarbon solvents to give improved yields of coupling products.
- Gutekunst, Gerhard,Brook, Adrian G.
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- Disilene Fluoride Adducts versus β-Halooligosilanides
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Extending the chemistry of disilene fluoride adducts studied earlier by us, we investigated the formation of 1,1-bis(trimethylsilyl)fluorodiphenylsilylsilanide, which was prepared by reaction of (Me3Si)3SiSiPh2F with KOtBu. The formed FPh2SiSi(Me3Si)2K displays distinctively different structural and spectroscopic features compared to the earlier reported F(Me3Si)2SiSi(SiMe3)2K. While the latter eliminates metal fluoride upon reaction with MgBr2, the respective magnesium silanide is formed from FPh2SiSi(Me3Si)2K. Reaction of (Me3Si)3SiSiPh2Cl with KOtBu proceeded similarly, but the formed ClPh2SiSi(Me3Si)2K easily undergoes potassium chloride elimination to the disilene Ph2SiSi(SiMe3)2. Compared to F(Me3Si)2SiSi(SiMe3)2K, which can be regarded as a disilene fluoride adduct, structural, spectroscopic, and reactivity properties of FPh2SiSi(Me3Si)2K distinguish it as a β-fluorodisilanide.
- Balatoni, Istvan,Hlina, Johann,Zitz, Rainer,P?cheim, Alexander,Baumgartner, Judith,Marschner, Christoph
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p. 14185 - 14192
(2019/10/14)
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- Tris(trimethylsilyl)silylboronate Esters: Novel Bulky, Air- and Moisture-Stable Silylboronate Ester Reagents for Boryl Substitution and Silaboration Reactions
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New, bulky tris(trimethylsilyl)silylboronate pinacol and hexylene glycol esters ((TMS)3Si-B(pin) and (TMS)3Si-B(hg)) were prepared in 46 and 61% yields, respectively, by the reaction of tris(trimethylsilyl)silylpotassium with the corresponding boron electrophiles. Notably, these silylboronate esters exhibited high stability to air and silica gel and were applied to the transition-metal-free boryl substitution of aryl halides, providing the desired borylated products in high yields with excellent B:Si ratios (up to 96% yield, B/Si = 99/1). These new silylboronate esters were also applied to a sequential borylation/cross-coupling process with various aryl halides, as well as the base-mediated silaboration of styrene.
- Yamamoto, Eiji,Shishido, Ryosuke,Seki, Tomohiro,Ito, Hajime
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supporting information
p. 3019 - 3022
(2017/09/05)
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- Synthesis, characterization and reactivity of yttrium and gadolinium silyl complexes
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The syntheses of yttrium and gadolinium-silyl complexes of the form R(Me3Si)2SiMI2(THF)3 (M = Y, Gd; R = Et, SiMe3) through reactions of potassium silyl reagents, KSiR(SiMe3)2(TH
- Sgro, Michael J.,Piers, Warren E.
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p. 243 - 250
(2014/12/10)
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- Allylsilanes in "tin-free" oximation, alkenylation, and allylation of alkyl halides
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Tin-free oximation, vinylation, and allylation of alkyl halides have been developed by using allylsilanes as di-tin surrogates. Initiation of the radical process with a peroxide provides the silyl radical, which can abstract a halogen from the corresponding alkyl halide. The resulting carbon-centered radical then adds to various acceptors, including a sulfonyloxime, a vinylsulfone, and an allylsulfone, leading to formation of the desired products along with the corresponding allylsulfone resulting from the reaction of the PhSO2 radical with the allylsilane precursor. Better results were generally obtained with methallylsilane 1b than with 1a. This observation was rationalized by invoking the higher nucleophilicity of 1b and the faster β-fragmentation of the corresponding β-silyl radical intermediate. Calculation of the energy barrier for the β-fragmentation of a series of β-silyl radicals at the DFT level supported this hypothesis. Finally, a second version of these oximation and vinylation reactions, based on the utilization of 3-tris(trimethylsilyl)silylthiopropene, was devised, affording the desired oximes and olefins in reasonable yields. This strategy allowed the title reaction to be performed under milder conditions (AIBN, benzene, 80°C), as a result of the easier β-fragmentation of the C-S bond as compared with the C-Si bond.
- Rouquet, Guy,Robert, Frederic,Mereau, Raphael,Castet, Frederic,Landais, Yannick
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supporting information; experimental part
p. 13904 - 13911
(2012/01/15)
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- Process for preparing tetrakis (trimethylsily) silane and tris (trimethysilyl) silane
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Tetrakis(trimethylsilyl)silane is prepared by reacting tetrachlorosilane with chlorotrimethylsilane in the presence of lithium metal, adding a compound with active proton(s) to the reaction mixture for treating the residual lithium metal therewith while maintaining the mixture neutral or acidic, and separating tetrakis(trimethylsilyl)silane from the organic layer. The residual lithium metal is treated in a safe and simple manner. Reaction of the tetrakis(trimethylsilyl)silane with an alkyl lithium or alkali metal alkoxide, followed by acid hydrolysis, affords tris(trimethylsilyl)silane. The desired compounds are prepared in high yields and on an industrial scale.
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Example 1 - 2
(2008/06/13)
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- Photolysis of tris(trimethylsilyl)silane: Trapping of sisyl radicals
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The photolysis of tris(trimethylsilyl)silane (TTMSS) was studied in the absence and in the presence of added trapping agents such as alkenes and alcohols. It was found that, unlike the case with pyrolysis, silyl radicals rather than silylenes are produced
- Mohamed, Mustafa,Brook, Michael A.
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p. 1357 - 1362
(2007/10/03)
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- Reactions of tris(trimethylsilyl) silanecarboxylates with organolithium reagents
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Chemical behavior of tris(trimethylsilyl)silanecarboxylates toward organolithium reagents was investigated. Treatment of triethylsilyl, triphenylsilyl, and methyl tris(trimethylsilyl)silanecarboxylate (1a - c) with organolithium reagents gave products which can be explained in terms of three types of reactions, the formation of lithium tris(trimethylsilyl)silanecarboxylate, abstraction of a trimethylsilyl group by the organolithium reagents, and addition of the organolithium reagents across the carbonyl bond. The formation of lithium tris(trimethylsilyl)silanecarboxylate was observed in the reactions of silyl carboxylates 1a and 1b, while addition of the organolithium to the carbonyl bond occurred in the reactions of 1b and 1c. Abstraction of a trimethytsilyl group was observed when tris(trimethylsilyl)silyllithium was used as the organolithium reagent. The reaction of 1b with dimethylphenylsilyllithium afforded dimethylphenylsilyl tris(trimethylsilyl)silyl ketone in good yield, but the bis(silyl) ketone thus formed readily underwent evolution of carbon monoxide even at -80°C, yielding (dimethylphenylsilyl)tris(trimethylsilyl)silane.
- Ohshita, Joji,Nekoda, Eri,Masaoka, Shin,Ishikawa, Mitsuo
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- Reductive Coupling of 2,2-Dibromo-1,1,1,3,3,3-hexaalkyltrisilanes. A Novel Route to Persilylcyclotetrasilanes of the Type 1R2R3Si)2Si>4
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Persilylcyclotetrasilanes of the type 1R2R3Si)2Si>4 (R1=R2=R3=Me; R1=Et, R2=R3=Me) were readily obtained by the reductive coupling of the corresponding 2,2-dibromo-1,1,1,3,3,3-hexaalkyltrisilanes using sodium; the Si4 frameworks of these persilyl compounds act as much more intense chromophore than those of peralkyl analogues.
- Matsumoto, Hideyuki,Yokoyama, Noriyasu,Sakamoto, Atsushi,Aramaki, Yumiko,Endo, Reiko,Nagai, Yoichiro
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p. 1643 - 1646
(2007/10/02)
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- The Synthesis of the First Spiropentasilane, Octamethylspiropentasilane
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The action of lithium metal on tetrakis(dimethylbromosilyl)silane or tetrakis(dimethylchlorosilyl)silane in tetrahydrofuran produces the first spiropentasilane, a highly strained polysilane that undergoes efficient cleavage reactions with lithium aluminium hydride, methylmagnesium bromide, and phosphorus pentachloride.
- Boudjouk, Philip,Sooriyakumaran, Ratnasabapathy
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p. 777 - 778
(2007/10/02)
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- Aluminium Chloride Catalyzed Skeletal Rearrangement of Permethylated Acyclic Polysilanes
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Permethylated linear polysilanes, Me(Me2Si)nMe with n = 4-10 and 12, underwent skeletal rearrangement to give branched isomers in almost quantitative yields when treated with a catalytic amount of aluminium chloride in refluxing benzene.From the linear polysilanes with n = 4, 5, and 6, (Me3Si)3SiMe, (Me3Si)4Si, and (Me3Si)SiSiMe2SiMe3 were obtained, respectively, as single isomer.The polysilanes with n = 7, 8, and 9 were converted into an equilibrium mixture, each consisting of a pair of branched isomers: (Me3Si)SiSiMe32SiMe2SiMe3 (15) and (Me3Si)SiSiMe(SiMe3)2 (16); (Me3Si)3SiSiMe2SiMe(SiMe3)2 (18) and 2 (19); and (Me3Si)3SiSiMe2SiMe2SiMe(SiMe3)2 and 2SiMe2 respectively.Under identical conditions, from 15 an equilibrium mixture of 15 and 16 was formed, while from 19 an equilibrium mixture of 18 and 19 was formed.Isomerization of the polysilane with n = 10 produced 2 as a single product, and the polysilane with n = 12 was converted to a single isomer 2.The 29Si NMR chemical shifts for permethylated linear polysilanes with n = 4-12 and for isomerization products are recorded.
- Ishikawa, Mitsuo,Iyoda, Jun,Ikeda, Haruhiko,Kotake, Kazunori,Hashimoto, Toshio,Kumada, Makoto
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p. 4845 - 4850
(2007/10/02)
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- Tris(trimethylsilyl)silyllithium
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An investigation has been made of the relative reactivity of tris(trimethylsilyl)silyllithium (I) in an attempt to estimate the importance of (dπ-pπ) bonding involving two contiguous silicon atoms. The procedure used were: (1) a comparative metalation reaction; (2) a kinetic study; and (3) a cleavage reaction of a silicon-silicon bond. The results are not definitive; although they seem to imply that the reactivity of I is comparable to or less than that of triphenylsilyllithium. The reactivity of I, together with its ultraviolet and NMR spectra, has been explained in terms of dative π-bonding.
- Gilman, Henry,Smith, Clifford L.
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