789-25-3Relevant articles and documents
Hydride transfer reactions between penta- and tetra-coordinate silicon derivatives
Corriu, R.J.P.,Guerin, C.,Henner, B.J.L.,Wang, Q.
, p. C1 - C5 (1992)
K has been found to reduce Ph3SiF and Ph3SiCl and to induce H/D exchange with Ph3SiD and Ph2SiD2.The mechanism of this exchange seems to be a one-step concerted mechanism through an intermediate with bridging hydrogen and deuterium atoms.
The Role of (tBuPOCOP)Ir(I) and Iridium(III) Pincer Complexes in the Catalytic Hydrogenolysis of Silyl Triflates into Hydrosilanes
Berthet, Jean-Claude,Cantat, Thibault,Durin, Gabriel,Nicolas, Emmanuel,Thuéry, Pierre
supporting information, (2021/12/09)
Hydrosilanes are convenient reductants for a large variety of organic substrates, but they are produced via energy-intensive processes. These limitations call for the development of general catalytic processes able to transform Si-O into Si-H bonds. We report here the catalytic hydrogenolysis of R3SiOTf (R = Me, Et, and Ph) species in the presence of a base (e.g., NEt3), by the hydride complexes [(tBuPOCOP)IrH(X)] (X = H and OTf; (tBuPOCOP = [C6H3-2,6(OPtBu)2]. Syntheses and crystal structures of new iridium(I) and iridium(III) complexes are presented as well as their role in the R3SiOTf to R3SiH transformation. The mechanisms of these reactions have been examined by DFT studies, revealing that the active species involved in the reduction of the Si-OTf vs Si-Cl bond are different. The rate-determining transition state is a base-assisted splitting of H2, forming an iridium(III) dihydride species.
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.
Organocalcium Complex-Catalyzed Selective Redistribution of ArSiH3or Ar(alkyl)SiH2to Ar3SiH or Ar2(alkyl)SiH
Li, Tao,McCabe, Karl N.,Maron, Laurent,Leng, Xuebing,Chen, Yaofeng
, p. 6348 - 6356 (2021/05/29)
Calcium is an abundant, biocompatible, and environmentally friendly element. The use of organocalcium complexes as catalysts in organic synthesis has had some breakthroughs recently, but the reported reaction types remain limited. On the other hand, hydrosilanes are highly important reagents in organic and polymer syntheses, and redistribution of hydrosilanes through C-Si and Si-H bond cleavage and reformation provides a straightforward strategy to diversify the scope of such compounds. Herein, we report the synthesis and structural characterization of two calcium alkyl complexes supported by β-diketiminato-based tetradentate ligands. These two calcium alkyl complexes react with PhSiH3 to generate calcium hydrido complexes, and the stability of the hydrido complexes depends on the supporting ligands. One calcium alkyl complex efficiently catalyzes the selective redistribution of ArSiH3 or Ar(alkyl)SiH2 to Ar3SiH and SiH4 or Ar2(alkyl)SiH and alkylSiH3, respectively. More significantly, this calcium alkyl complex also catalyzes the cross-coupling between the electron-withdrawing substituted Ar(R)SiH2 and the electron-donating substituted Ar′(R)SiH2, producing ArAr′(alkyl)SiH in good yields. The synthesized ArAr′(alkyl)SiH can be readily transferred to other organosilicon compounds such as ArAr′(alkyl)SiX (where X = OH, OEt, NEt2, and CH2SiMe3). DFT investigations are carried out to shed light on the mechanistic aspects of the redistribution of Ph(Me)SiH2 to Ph2(Me)SiH and reveal the low activation barriers (17-19 kcal/mol) in the catalytic reaction.
Hydrogenolysis of Polysilanes Catalyzed by Low-Valent Nickel Complexes
Comas-Vives, Aleix,Eiler, Frederik,Grützmacher, Hansj?rg,Pribanic, Bruno,Trincado, Monica,Vogt, Matthias
supporting information, p. 15603 - 15609 (2020/04/29)
The dehydrogenation of organosilanes (RxSiH4?x) under the formation of Si?Si bonds is an intensively investigated process leading to oligo- or polysilanes. The reverse reaction is little studied. To date, the hydrogenolysis of Si?Si bonds requires very harsh conditions and is very unselective, leading to multiple side products. Herein, we describe a new catalytic hydrogenation of oligo- and polysilanes that is highly selective and proceeds under mild conditions. New low-valent nickel hydride complexes are used as catalysts and secondary silanes, RR′SiH2, are obtained as products in high purity.
Highly selective redistribution of primary arylsilanes to secondary arylsilanes catalyzed by Ln(CH2C6H4NMe2-: O)3@SBA-15
Guo, Chenjun,Li, Min,Chen, Jue,Luo, Yunjie
supporting information, p. 117 - 120 (2019/12/25)
Rare-earth metal tris(aminobenzyl) complexes Ln(CH2C6H4NMe2-o)3 (Ln = La, Y) were grafted onto the dehydroxylated periodic mesoporous silica support SBA-15 to generate the organometallic-inorganic hybrid materials Ln(CH2C6H4NMe2-o)3@SBA-15 (Ln = La (2a), Y (2b)), which demonstrated extremely high selectivity (>99%) in catalyzing the redistribution of primary arylsilanes to secondary arylsilanes without the requisition of strict control of the reaction conditions. The hybrid materials still showed a perfect selectivity and activity after three catalytic cycles.
Electrochemical properties of arylsilanes
Biedermann, Judith,Wilkening, H. Martin R.,Uhlig, Frank,Hanzu, Ilie
, p. 13 - 18 (2019/03/27)
In the past, the electrochemical properties of organosilicon compounds were investigated for both fundamental reasons and synthesis purposes. Little is, however, known about the electrochemical behaviour of hydrogen-bearing arylsilanes. Here, we throw light on the electrochemical properties of 11 arylsilanes compounds, 2 of them synthesized for the first time. The oxidation potentials are found to depend on both the nature and number of the aryl groups. Based on these findings it was possible to establish some variation trends that match the expected structure–property correlations. Furthermore, we present first insights into the electrochemical reaction kinetics behind and identify several soluble electrochemical oxidation products.
Synthesis of hydrosilanes: Via Lewis-base-catalysed reduction of alkoxy silanes with NaBH4
Aoyagi, Keiya,Ohmori, Yu,Inomata, Koya,Matsumoto, Kazuhiro,Shimada, Shigeru,Sato, Kazuhiko,Nakajima, Yumiko
supporting information, p. 5859 - 5862 (2019/05/27)
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.
Nucleophile induced ligand rearrangement reactions of alkoxy- and arylsilanes
Docherty, Jamie H.,Dominey, Andrew P.,Thomas, Stephen P.
, p. 3330 - 3335 (2019/05/10)
The ligand-redistribution reactions of aryl- and alkoxy-hydrosilanes can potentially cause the formation of gaseous hydrosilanes, which are flammable and pyrophoric. The ability of generic nucleophiles to initiate the ligand-redistribution reaction of commonly used hydrosilane reagents was investigated, alongside methods to hinder and halt the formation of hazardous hydrosilanes. Our results show that the ligand-redistribution reaction can be completely inhibited by common electrophiles and first-row transition metal pre-catalysts.
Distinct Catalytic Performance of Cobalt(I)- N -Heterocyclic Carbene Complexes in Promoting the Reaction of Alkene with Diphenylsilane: Selective 2,1-Hydrosilylation, 1,2-Hydrosilylation, and Hydrogenation of Alkene
Gao, Yafei,Wang, Lijun,Deng, Liang
, p. 9637 - 9646 (2018/10/02)
Selectivity control on the reaction of alkene with hydrosilane is a challenging task in the development of non-precious-metal-based hydrosilylation catalysts. While the traditional way of selectivity control relies on the use of different ligand type and/or different metals, we report herein that cobalt(I) complexes bearing different N-heterocyclic carbene ligands (NHCs) exhibit distinct selectivity in catalyzing the reaction of alkene with Ph2SiH2. [(IAd)(PPh3)CoCl] (IAd = 1,3-diadamantylimidazol-2-ylidene) is an efficient catalyst for anti-Markovnikov hydrosilylation of monosubstituted alkenes. [(IMes)2CoCl] (IMes = 1,3-dimesitylimidazol-2-ylidene) shows Markovnikov-addition selectivity in promoting the hydrosilylation of aryl-substituted alkenes. [(IMe2Me2)4Co][BPh4] (IMe2Me2 = 1,3-dimethyl-4,5-dimethylimidazol-2-ylidene) can catalyze hydrogenation of alkenes with Ph2SiH2 as the terminal hydrogen source. Mechanistic studies in combination with the knowledge on the steric nature of cobalt-NHC species suggest that (NHC)cobalt(I) silyl species and bis(NHC)cobalt(I) hydride species are the probable key intermediates for these hydrosilylation and hydrogenation reactions, respectively. The different steric nature of IAd versus IMes and the potential of IMes incurring π···π interaction with aryl-substituted alkenes are thought to be the causes of the observed 1,2- and 2,1-addition selectivity.
