1066-54-2Relevant articles and documents
Silylation of Alcohols, Phenols, and Silanols with Alkynylsilanes – an Efficient Route to Silyl Ethers and Unsymmetrical Siloxanes
Kuciński, Krzysztof,Stachowiak, Hanna,Hreczycho, Grzegorz
, p. 4042 - 4049 (2020)
The formation of several silyl ethers (alkoxysilanes, R3Si-OR') and unsymmetrical siloxanes (R3Si-O-SiR'3) can be catalyzed by the commercially available potassium bis(trimethylsilyl)amide (KHMDS). The reaction proceeds via direct dealkynative coupling between various alcohols or silanols and alkynylsilanes, with a simultaneous formation of gaseous acetylene as the sole by-product. The dehydrogenative and dealkenative coupling of alcohols or silanols are well-investigated, whilst the utilization of alkynylsilanes as silylating agents has never been comprehensively studied in this context. Overall, the presented system allows the synthesis of various attractive organosilicon compounds under mild conditions, making this approach an atom-efficient, environmentally benign, and sustainable alternative to existing synthetic solutions.
Unique σ-bond metathesis of silylalkynes promoted by an ansa-dimethylsilyl and oxo-bridged uranium metallocene
Wang, Jiaxi,Gurevich, Ylia,Botoshansky, Mark,Eisen, Moris S.
, p. 9350 - 9351 (2006)
The tetrachloride salt of uranium reacts with 1 equiv of the lithium ligand Li2[(C5Me4)2SiMe2] in DME to form the complex [η5-(C5Me4)2SiMe2]UCl2·2LiCl·2DME (1), which undergoes a rapid hydrolysis in toluene to yield the dimeric bridged monochloride, monooxide complex [{[η5-(C5Me4)2SiMe2]UCl}2(μ-O)(μ-Cl)?Li?1/2DME]2 (2). Metathesis of 2 with BuLi in DME gives the mono-bridged dibutyl complex {[η5-(C5Me4)2SiMe2]UBu}2(μ-O) (3). Complex 2 was characterized by solid-state X-ray analysis. Complex 3 was found to be an active catalyst for the disproportionation metathesis of TMSC≡CH (TMS = SiMe3) and the cross-metathesis of TMSC≡CH or TMSC≡CTMS with various terminal alkynes. The metathesis of TMSC≡CH gives TMSC≡CTMS and HC≡CH, whereas the cross-metathesis of TMSC≡CH or TMSC≡CTMS with terminal alkynes (RC≡CH) yields TMSC≡CTMS, TMSC≡CR, and HC≡CH. In addition, TMSC≡CCH3 also was found to react with tBuC≡CH, yielding TMSC≡CBut and CH3C≡CH. A plausible mechanism for the catalytic process is presented. Copyright
Mechanistic Studies and Expansion of the Substrate Scope of Direct Enantioselective Alkynylation of α-Ketiminoesters Catalyzed by Adaptable (Phebox)Rhodium(III) Complexes
Morisaki, Kazuhiro,Sawa, Masanao,Yonesaki, Ryohei,Morimoto, Hiroyuki,Mashima, Kazushi,Ohshima, Takashi
, p. 6194 - 6203 (2016)
Mechanistic studies and expansion of the substrate scope of direct enantioselective alkynylation of α-ketiminoesters catalyzed by adaptable (phebox)rhodium(III) complexes are described. The mechanistic studies revealed that less acidic alkyne rather than more acidic acetic acid acted as a proton source in the catalytic cycle, and the generation of more active (acetato-κ2O,O′)(alkynyl)(phebox)rhodium(III) complexes from the starting (diacetato)rhodium(III) complexes limited the overall reactivity of the reaction. These findings, as well as facile exchange of the alkynyl ligand on the (alkynyl)rhodium(III) complexes led us to use (acetato-κ2O,O′)(trimethylsilylethynyl)(phebox)rhodium(III) complexes as a general precatalyst for various (alkynyl)rhodium(III) complexes. Use of the (trimethylsilylethynyl)rhodium(III) complexes as precatalysts enhanced the catalytic performance of the reactions with an α-ketiminoester derived from ethyl trifluoropyruvate at a catalyst loading as low as 0.5 mol % and expanded the substrate scope to unprecedented α-ketiminophosphonate and cyclic N-sulfonyl α-ketiminoesters.
Lewis base mediated β-elimination and lewis acid mediated insertion reactions of disilazido zirconium compounds
Yan, Kaking,Duchimaza Heredia, Juan J.,Ellern, Arkady,Gordon, Mark S.,Sadow, Aaron D.
, p. 15225 - 15237 (2013)
The reactivity of a series of disilazido zirconocene complexes is dominated by the migration of anionic groups (hydrogen, alkyl, halide, OTf) between the zirconium and silicon centers. The direction of these migrations is controlled by the addition of two-electron donors (Lewis bases) or two-electron acceptors (Lewis acids). The cationic nonclassical [Cp2ZrN(SiHMe 2)2]+ ([2]+) is prepared from Cp2Zr{N(SiHMe2)2}H (1) and B(C 6F5)3 or [Ph3C][B(C 6F5)4], while reactions of B(C 6F5)3 and Cp2Zr{N(SiHMe 2)2}R (R = Me (3), Et (5), n-C3H7 (7), CH? -CHSiMe3 (9)) provide a mixture of [2]+ and [Cp2ZrN(SiHMe2)(SiRMe2)]+. The latter products are formed through B(C6F5)3 abstraction of a β-H and R group migration from Zr to the β-Si center. Related β-hydrogen abstraction and X group migration reactions are observed for Cp2Zr{N(SiHMe2)2}X (X = OTf (11), Cl (13), OMe (15), O-i-C3H7 (16)). Alternatively, addition of DMAP (DMAP = 4-(dimethylamino)pyridine) to [2]+ results in coordination to a Si center and hydrogen migration to zirconium, giving the cationic complex [Cp2Zr{N(SiHMe2)(SiMe2DMAP)}H] + ([19]+). Related hydrogen migration occurs from [Cp 2ZrN(SiHMe2)(SiMe2OCHMe2)] + ([18]+) to give [Cp2Zr{N(SiMe 2DMAP)(SiMe2OCHMe2)}H]+ ([22] +), whereas X group migration is observed upon addition of DMAP to [Cp2ZrN(SiHMe2)(SiMe2X)]+ (X = OTf ([12]+), Cl ([14]+)) to give [Cp 2Zr{N(SiHMe2)(SiMe2DMAP)}X]+ (X = OTf ([26]+), Cl ([20]+)). The species involved in these transformations are described by resonance structures that suggest β-elimination. Notably, such pathways are previously unknown in early metal amide chemistry. Finally, these migrations facilitate direct Si-H addition to carbonyls, which is proposed to occur through a pathway that previously had been reserved for later transition metal compounds.
A new synthetic route to donor-acceptor porphyrins
Plater, M.John,Aiken, Stuart,Bourhill, Grant
, p. 2405 - 2413 (2002)
Some new donor-acceptor porphyrins have been prepared based on a metallated bis(ethynyl) porphyrin core. 4-(Dimethylamino)phenyl was used as the donor group and 4-nitrophenyl, 4-cyanophenyl and 5-nitrothiazoyl as the acceptor groups. Dipyrrylmethane was used for large scale porphyrin ring synthesis because the absence of methylene substituents reduces the difficulty of substituent scrambling that occurs during porphyrin synthesis.
Simple procedures for ethynylmagnesium bromide, ethynyltrialkylsilanes and ethynyltrialkylstannanes
Brandsma,Verkruijsse
, p. 1727 - 1728 (1999)
1 Molar solutions of ethynylmagnesium bromide in tetrahydrofuran can be successfully prepared by introducing acetylene into a cooled solution of ethylmagnesium bromide. Subsequent reaction with trialkylsilyl or trialkylstannyl chloride gives the expected ethynyl derivatives in excellent yields.
Preparation of a Diethynyl Hypervalent Silicon Monomer by Coordination-selective Cleavage: Structure and Polymerization to give Novel Polycarbosilanes containing Main-chain Hexacoordinate Silicon
Boyer-Elma, Karine,Carre, Francis H.,Corriu, Robert J.-P.,Douglas, William E.
, p. 725 - 726 (1995)
The hexacoordinate monomer R2Si(CCH)2 , formed from R2Si(CCSiMe3)2 by coordination-selective cleavage of the trimethylsilyl-acetylene bonds in the presence of Bun4NF, undergoes palladium-catalysed cross-coupling polymerization with dihaloarenes to afford novel polycarbosilanes n (Ar = 1,4-phenylene, 4,4'-biphenylene, 9,10-anthrylene) containing hexacoordinate silicon.
Trimethylsilylacetylene synthesis process
-
Paragraph 0024; 0025, (2021/01/11)
The invention discloses a process route for synthesizing trimethylsilylacetylene, which comprises the following steps of: generating trimethylchlorosilylethylene by taking ethylene bromide and trimethylchlorosilane as initial raw materials through a Grignard method, and forming 1-bromo trimethylchlorosilylethylene under the action of alkali through a bromination reagent; and removing monomolecularhydrogen bromide under the action of strong alkali to generate trimethylsilylacetylene. Compared with the traditional process, the process route has the advantages that the use of gas acetylene is avoided, the risk is reduced, the safety is improved, the used raw materials are easily available, the operation is easy, the safety and the environmental protection are realized, and the industrial production can be realized.
Three-coordinate copper(II) alkynyl complex in C-C bond formation: The sesquicentennial of the glaser coupling
Warren, Timothy H.,Bakhoda, Abolghasem,Okoromoba, Otome E.,Greene, Christine,Boroujeni, Mahdi Raghibi,Bertke, Jeffery A.
supporting information, p. 18483 - 18490 (2020/11/27)
Copper(II) alkynyl species are proposed as key intermediates in numerous Cu-catalyzed C-C coupling reactions. Supported by a β-diketiminate ligand, the three-coordinate copper(II) alkynyl [CuII]-C≡CAr (Ar = 2,6-Cl2C6H3) forms upon reaction of the alkyne H-C≡CAr with the copper(II) tertbutoxide complex [CuII]-OtBu. In solution, this [CuII]-C≡CAr species cleanly transforms to the Glaser coupling product ArC≡C-C≡CAr and [CuI](solvent). Addition of nucleophiles R′C≡C-Li (R′ = aryl, silyl) and Ph-Li to [CuII]-C≡CAr affords the corresponding Csp-Csp and Csp-Csp2 coupled products RC≡C-C≡CAr and Ph-C≡CAr with concomitant generation of [CuI](solvent) and {[CuI]-C≡CAr}-, respectively. Supported by density functional theory (DFT) calculations, redox disproportionation forms [CuIII](C≡CAr)(R) species that reductively eliminate R-C≡CAr products. [CuII]-C≡CAr also captures the trityl radical Ph3C· to give Ph3C-C≡CAr. Radical capture represents the key Csp-Csp3 bond-forming step in the copper-catalyzed C-H functionalization of benzylic substrates R-H with alkynes H-C≡CR′ (R′ = (hetero)aryl, silyl) that provide Csp-Csp3 coupled products R-C≡CR via radical relay with tBuOOtBu as oxidant.
Preparation technology of trimethylsilylacetylene
-
Paragraph 0001; 0002, (2017/07/19)
Trimethylsilylacetylene is an important chemical product. The technological process comprises steps as follows: (1) preparation of an n-butyl magnesium chloride Grignard reagent; (2) preparation of a unilateral ethynylmagnesium chloride Grignard reagent; (3) preparation of trimethylsilylacetylene; (4) distillation; (5) washing; (6) removal of calcium chloride by suction filtration; (7) atmospheric distillation.
