1048-08-4Relevant articles and documents
Hypervalent silicon hydrides: evidence for their intermediacy in the exchange reactions of di- and tri-hydrogenosilanes catalysed by hydrides (NaH, KH and LiAlH4)
Becker, B.,Corriu, R. J. P.,Guerin, C.,Henner, B. J. L.
, p. 147 - 154 (1989)
Di and tri-hydrogenosilanes, RR'SiH2 and RSiH3 (R=aryl, allyl or benzyl; R'=aryl or alkyl), readily undergo exchange reactions, involving silicon-carbon bonds and silicon-hydrogen bonds, in the presence of hydrides (LiAlH4, KH and NaH) as catalysts.These results are discussed in terms of five-coordinate silicon hydrides as intermediates in the reaction.
Disproportionation reactions of organohydrosilanes in the presence of base catalysts
Itoh, Masayoshi,Inoue, Koji,Ishikawa, Jun-Ichi,Iwata, Kenji
, p. 1 - 6 (2001)
Alkoxides, alkyl compounds, amides and hydrides of alkali metals (M) and barium, such as MOR, Ba(OR)2, n-BuM, PhM, MN(SiMe3)2 and MAlH4 showed high catalytic activities versus the disproportionation reactions of PhSiH3 to produce SiH4, Ph2SiH2 and Ph3SiH. A good correlation between the catalyst basicities and the catalytic activities was observed, and a reaction mechanism involving the metal hydride and alkyl metal was proposed. A considerable amount of SiH4 was produced in the reduction of PhSiCl3 with LiAlH4 when over three moles of LiAlH4 was used.
Nucleophilic attack of R-lithium at tetrahedral silicon in alkoxysilanes. An alternate mechanism
Furgal, Joseph C.,Laine, Richard M.
, p. 705 - 725 (2016)
The currently accepted mechanism for nucleophilic attack at silicon in tetraalkoxysilanes, e.g. Si(OEt)4 is suggested to involve formation of penta- and then hexacoordinated intermediates as supported by the apparent exclusive formation of R3SiOR′ and R4Si from nucleophilic attack by RLi and RMgX. Our recent discovery of a direct route from biogenic silica to tetraalkoxyspirosiloxanes prompted us to revisit this reaction as a potential route to diverse silicon-containing species with single SiC bonds as early studies demonstrate that spirosiloxanes form quite stable pentacoordinated alkoxysilane compounds. As anticipated, Si(2-methyl-2,4-pentanediolato)2 (SP) reacts with RLi (R = Ph, anthracene, phenylacetylene, etc.) at -78 °C to form pentacoordinated Si, e.g. LiPhSP equilibrates with the starting reagents even at 3:1 ratios of PhLi:SP with no evidence for formation of hexacoordinated species by mass spectral, NMR and quenching studies. Thus, quenching with MeI or Me3SiCl allows isolation of monosubstituted products from RLi:SP; RSi(OR′)3 including some ring-opened oligomers. Comparative studies of reactions of PhLi with Si(OEt)4 allows isolation of mono- and disubstituted products again even at 1:1 ratios of PhLi:Si(OEt)4. However, on standing at -78 °C for long periods of time or on warming to 0 °C, the primary product for both reactions is Ph4Si even with 0.5 equivalents of PhLi. At reaction temperatures ≥0 °C the primary product is again Ph4Si. These results suggest that hexacoordinated intermediates are not part of the substitution mechanism and may suggest that the higher-substituted compounds arise from disproportionation processes. We also briefly describe the conversion of anthracenylSP and 9,9-dimethylfluoreneSP to silsesquioxanes.
Continuous-flow Si-H functionalizations of hydrosilanesviasequential organolithium reactions catalyzed by potassiumtert-butoxide
Lee, Hyune-Jea,Kwak, Changmo,Kim, Dong-Pyo,Kim, Heejin
supporting information, p. 1193 - 1199 (2021/02/26)
We herein report an atom-economic flow approach to the selective and sequential mono-, di-, and tri-functionalizations of unactivated hydrosilanesviaserial organolithium reactions catalyzed by earth-abundant metal compounds. Based on the screening of various additives, we found that catalytic potassiumtert-butoxide (t-BuOK) facilitates the rapid reaction of organolithiums with hydrosilanes. Using a flow microreactor system, various organolithiums bearing functional groups were efficiently generatedin situunder mild conditions and consecutively reacted with hydrosilanes in the presence oft-BuOK within 1 min. We also successfully conducted the di-funtionalizations of dihydrosilane by sequential organolithium reactions, extending to a gram-scale-synthesis. Finally, the combinatorial functionalizations of trihydrosilane were achieved to give every conceivable combination of tetrasubstituted organosilane libraries based on a precise reaction control using an integrated one-flow system.
A well-defined NHC-Ir(III) catalyst for the silylation of aromatic C-H bonds: Substrate survey and mechanistic insights
Rubio-Pérez, Laura,Iglesias, Manuel,Munárriz, Julen,Polo, Victor,Passarelli, Vincenzo,Pérez-Torrente, Jesús J.,Oro, Luis A.
, p. 4811 - 4822 (2017/07/11)
A well-defined NHC-Ir(iii) catalyst, [Ir(H)2(IPr)(py)3][BF4] (IPr = 1,3-bis-(2,6-diisopropylphenyl)imidazol-2-ylidene), that provides access to a wide range of aryl- and heteroaryl-silanes by intermolecular dehydrogenative C-H bond silylation has been prepared and fully characterized. The directed and non-directed functionalisation of C-H bonds has been accomplished successfully using an arene as the limiting reagent and a variety of hydrosilanes in excess, including Et3SiH, Ph2MeSiH, PhMe2SiH, Ph3SiH and (EtO)3SiH. Examples that show unexpected selectivity patterns that stem from the presence of aromatic substituents in hydrosilanes are also presented. The selective bisarylation of bis(hydrosilane)s by directed or non-directed silylation of C-H bonds is also reported herein. Theoretical calculations at the DFT level shed light on the intermediate species in the catalytic cycle and the role played by the ligand system on the Ir(iii)/Ir(i) mechanism.
Application of the sila-Friedel-Crafts reaction to the synthesis of π-extended silole derivatives and their properties
Furukawa, Shunsuke,Kobayashi, Junji,Kawashima, Takayuki
experimental part, p. 9329 - 9336 (2011/01/07)
The intramolecular sila-Friedel-Crafts reaction was developed as a new method for the construction of a dibenzosilole skeleton. This reaction proceeds under mild conditions to afford the target in relatively good yield, indicating its availability as a versatile synthetic method. This reaction can be applied to the synthesis of π-extended silole derivatives such as ladder-type silafluorene 8 and spiro-type silabifluorene 9. Furthermore, the synthesis of two-dimensionally extended silole derivatives utilizing the sila-Friedel-Crafts reaction as the multiple intramolecular cyclization was achieved, including the first synthesis of trisilasumanene 18. The X-ray crystallographic analysis of trisilasumanene 18 demonstrated the planarity in the main π-framework, in contrast to sumanene and its sulfur analogue, trithiasumanene, bearing the bowl-shaped structures. In the UV-vis absorption spectra, the absorption bands of triphenylenosiloles 18 and 19 were slightly red-shifted compared to that of hexabutoxytriphenylene 22. The weak absorption bands were also observed in the longer-wavelength region in 18 and 19, which is derived from σ*-π* conjugation of the silole skeletons. In addition, 18 and 19 showed the blue fluorescence in dichloromethane and in the solid state. The Royal Society of Chemistry.
Efficient preparation of monohydrosilanes using palladium-catalyzed Si-C bond formation
Yamanoi, Yoshinori,Taira, Takafumi,Sato, Jun-Ichi,Nakamula, Ikuse,Nishihara, Hiroshi
, p. 4543 - 4546 (2008/03/13)
(Chemical Equation Presented) The arylation of dihydrosilanes with aryl iodides or heteroaryl iodides in the presence of a palladium catalyst provides the corresponding monohydrosilanes in good to high yield. Moderate to good yields are obtained even in the presence of a variety of reactive functional groups, such as -NH2, -OH, or -CN, without their protection.
Reactions of organolanthanide compounds RLnI (Ln = Yb, Eu, Sm) with organic derivatives of silicon, tin, lead, and antimony
Rybakova,Syutkina,Petrov
, p. 244 - 246 (2007/10/03)
Reactions of compounds RLnI (R = Alk, Ar; Ln = Yb, Eu, Sm) with hexaalkyl(aryl)-distannanes, trimethylsilyltriphenyltin, and lead and antimony acetates were studied. The reactions with Sn-Sn and Si-Sn organic derivatives result in cleavage of Sn-Sn amd Sn-Si bonds with formation of tetrasubstituted stannanes and reactive organometallic derivatives with an Sn-Ln or Si-Ln bond. The reactions of RYbI with lead and antimony acetates and with tetraethoxysilane cause cleavage of the Pb-O, Sb-O, or Si-O bond with formation of tetrasubstituted derivatives of lead and silicon or trisubstituted antimony derivatives.
Utilization of bottoms of the direct synthesis of methylchlorosilanes in production of the crude mixtures of phenylethoxysilanes by continuous organomagnesium Procedure
Klokov
, p. 476 - 478 (2007/10/03)
Utilization of the bottoms after distillation of methylchlorosilanes in continuous organomagnesium synthesis of organosilicon raw materials for production of polyphenylsiloxane resins and lacquers and enamels based on them was analyzed.
Reactions of tris(trimethylsilyl) silanecarboxylates with organolithium reagents
Ohshita, Joji,Nekoda, Eri,Masaoka, Shin,Ishikawa, Mitsuo
, p. 49 - 54 (2007/10/03)
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.
