72761-85-4Relevant academic research and scientific papers
Markovnikov Hydrosilylation of Alkynes with Tertiary Silanes Catalyzed by Dinuclear Cobalt Carbonyl Complexes with NHC Ligation
Deng, Liang,Lai, Yuhang,Leng, Xuebing,Wang, Dongyang,Wang, Peng,Xiao, Jie
supporting information, p. 12847 - 12856 (2021/08/24)
Metal-catalyzed hydrosilylation of alkynes is an ideal atom-economic method to prepare vinylsilanes that are useful reagents in the organic synthesis and silicone industry. Although great success has been made in the preparation of β-vinylsilanes by metal-catalyzed hydrosilylation reactions of alkynes, reported metal-catalyzed reactions for the synthesis of α-vinylsilanes suffer from narrow substrate scope and/or poor selectivity. Herein, we present selective Markovnikov hydrosilylation reactions of terminal alkynes with tertiary silanes using a dicobalt carbonyl N-heterocyclic carbene (NHC) complex [(IPr)2Co2(CO)6] (IPr = 1,3-di(2,6-diisopropylphenyl)imidazol-2-ylidene) as catalyst. This cobalt catalyst effects the hydrosilylation of both alkyl- and aryl-substituted terminal alkynes with a variety of tertiary silanes with good functional group compatibility, furnishing α-vinylsilanes with high yields and high α/β selectivity. Mechanistic study revealed that the stoichiometric reactions of [(IPr)2Co2(CO)6] with PhCCH and HSiEt3 can furnish the dinuclear cobalt alkyne and mononuclear cobalt silyl complexes [(IPr)(CO)2Co(μ-ν2:ν2-HCCPh)Co(CO)3], [(IPr)(CO)2Co(μ- ν2:ν2-HCCPh)Co(CO)2(IPr)], and [(IPr)Co(CO)3(SiEt3)], respectively. Both dicobalt bridging alkyne complexes can react with HSiEt3 to yield α-triethylsilyl styrene and effect the catalytic Markovnikov hydrosilylation reaction. However, the mono(NHC) dicobalt complex [(IPr)(CO)2Co(μ- ν2:ν2-HCCPh)Co(CO)3] exhibits higher catalytic activity over the di(NHC)-dicobalt complexes. The cobalt silyl complex [(IPr)Co(CO)3(SiEt3)] is ineffective in catalyzing the hydrosilylation reaction. Deuterium labeling experiments with PhCCD and DSiEt3 indicates the syn-addition nature of the hydrosilylation reaction. The absence of deuterium scrambling in the hydrosilylation products formed from the catalytic reaction of PhCCH with a mixture of DSiEt3 and HSi(OEt)3 hints that mononuclear cobalt species are less likely the in-cycle species. These observations, in addition to the evident of nonsymmetric Co2C2-butterfly core in the structure of [(IPr)(CO)2Co(μ- ν2:ν2-HCCPh)Co(CO)3], point out that mono(IPr)-dicobalt species are the genuine catalysts for the cobalt-catalyzed hydrosilylation reaction and that the high α selectivity of the catalytic system originates from the joint play of the dicobalt carbonyl species to coordinate alkynes in the Co(μ- ν2:ν2-HCCR′)Co mode and the steric demanding nature of IPr ligand.
The cobalt(II) complex of a new tridentate Schiff-base ligand as a catalyst for hydrosilylation of olefins
Gorczyński, Adam,Zaranek, MacIej,Witomska, Samanta,Bocian, Aleksandra,Stefankiewicz, Artur R.,Kubicki, MacIej,Patroniak, Violetta,Pawlu?, Piotr
, p. 71 - 74 (2016/02/26)
Condensation of 1-methyl-2-imidazolecarboxaldehyde with 2-(1-methylhydrazinyl)pyridine results in the synthesis of new, tridentate Schiff-base ligand L, which readily reacts with CoCl2 to form a monometallic [CoLCl2] complex that, upon reduction, functions as active hydrosilylation catalyst. The ligand and the [CoLCl2] catalyst have been characterized spectroscopically (MS, NMR, FTIR) and by single crystal X-ray diffraction techniques. The results of preliminary catalytic experimentation show that the cobalt complex can induce hydrosilylation and dehydrogenative silylation of olefins, depending upon the hydrosilane substrate used.
Synthesis and catalytic application of: N -heterocyclic carbene copper complex functionalized conjugated microporous polymer
Zhou, Hui,Zhang, Qing-Yong,Lu, Xiao-Bing
, p. 44995 - 45000 (2016/06/06)
A N-heterocyclic carbene copper(i) complex functionalized conjugated microporous polymer (CMP-NHC-CuCl) was synthesized by palladium-catalyzed Sonogashira cross-coupling chemistry. The resulting CMP-NHC-CuCl proved to be a good heterogeneous catalyst in the hydrosilylation of functionalized terminal alkynes with boryldisiloxane to afford (β,β)-(E)-vinyldisiloxane with high stereoselectivity, and the catalyst could be used four times without obvious loss in catalytic activity. Moreover, CMP-NHC-CuCl was also efficient in catalyzing the hydrosilylation of CO2 with triethoxysilane to form silyl formate under mild conditions.
Copper(I)-catalyzed highly regio- and stereoselective hydrosilylation of terminal alkynes with boryldisiloxane
Zhou, Hui,Wang, Yan-Bo
, p. 2512 - 2516 (2015/04/14)
By employing 1,1,3,3-tetramethyl-1,3-(pinacolboryl)disiloxane as a novel silicon source, the N-heterocyclic carbene copper complex catalyzed hydrosilylation of terminal alkynes was developed to prepare vinyldisiloxanes in a highly regio- and stereoselective manner. A number of functional groups, including ether, ester, cyano, nitro, halo, hydroxyl, cyclopropyl, and aryl groups, were tolerated under the optimized conditions. A mechanistic investigation was undertaken by using density functional theory calculations. This approach allows facile entry to unsymmetrical disubstituted (E)-alkenes by Pd-catalyzed cross-coupling reactions.
Preparation of vinyl silyl ethers and disiloxanes via the silyl-heck reaction of silyl ditriflates
Martin, Sara E. S.,Watson, Donald A.
supporting information, p. 13330 - 13333 (2013/09/24)
Vinyl silyl ethers and disiloxanes can now be prepared from aryl-substituted alkenes and related substrates using a silyl-Heck reaction. The reaction employs a commercially available catalyst system and mild conditions. This work represents a highly practical means of accessing diverse classes of vinyl silyl ether substrates in an efficient and direct manner with complete regiomeric and geometric selectivity.
Palladium-catalysed cross-coupling of vinyldisiloxanes with benzylic and allylic halides and sulfonates
Frye, Elizabeth C.,O'Connor, Cornelius J.,Twigg, David G.,Elbert, Bryony,Laraia, Luca,Hulcoop, David G.,Venkitaraman, Ashok R.,Spring, David R.
supporting information; experimental part, p. 8774 - 8779 (2012/09/21)
The Hiyama cross-coupling reaction is a powerful method for carbon-carbon bond formation. To date, the substrate scope of this reaction has predominantly been limited to sp2-sp2 coupling reactions. Herein, the palladium-catalysed Hiyama type cross-coupling of vinyldisiloxanes with benzylic and allylic bromides, chlorides, tosylates and mesylates is reported. A wide variety of functional groups were tolerated, and the synthetic utility of the methodology was exemplified through the efficient total synthesis of the cytotoxic natural product bussealin A. In addition, the antiproliferative ability of bussealin A was evaluated in two cancer-cell lines. Copyright
Vinyldisiloxanes: Their synthesis, cross coupling and applications
Sore, Hannah F.,Boehner, Christine M.,Laraia, Luca,Logoteta, Patrizia,Prestinari, Cora,Scott, Matthew,Williams, Katharine,Galloway, Warren R. J. D.,Spring, David R.
experimental part, p. 504 - 515 (2011/03/17)
During the studies towards the development of pentafluorophenyldimethylsilanes as a novel organosilicon cross coupling reagent it was revealed that the active silanolate and the corresponding disiloxane formed rapidly under basic conditions. The discovery that disiloxanes are in equilibrium with the silanolate led to the use of disiloxanes as cross coupling partners under fluoride free conditions. Our previous report focused on the synthesis and base induced cross coupling of aryl substituted vinyldisiloxanes with aryl halides; good yields and selectivities were achieved. As a continuation of our research, studies into the factors which influence the successful outcome of the cross coupling reaction with both alkyl and aryl substituted vinyldisiloxanes were examined and a proposed mechanism discussed. Further investigation into expanding the breadth and diversity of substituted vinyldisiloxanes in cross coupling was explored and applied to the synthesis of unsymmetrical trans-stilbenes and cyclic structures containing the trans-alkene architecture.
Fluoride-free cross coupling using vinyldisiloxanes
Sore, Hannah F.,Boehner, Christine M.,MacDonald, Simon J. F.,Norton, David,Fox, David J.,Spring, David R.
supporting information; experimental part, p. 1068 - 1071 (2009/05/30)
Vinyldisiloxanes equilibrate with the corresponding silanolates under basic conditions and subsequently undergo palladium catalysed cross coupling with aryl/heteroaryl iodides and bromides. The Royal Society of Chemistry 2009.
A novel approach to stilbenoid dendrimer core synthesis
Pruka?a, Wies?aw
experimental part, p. 3026 - 3030 (2009/07/03)
A new synthetic protocol for the one-pot, stereoselective synthesis of 1,3,5-tris[(E)-4-halostyryl]benzene and 1,2,4,5-tetrakis[(E)-4-halostyryl] benzene derivatives as stilbenoid dendrimer cores via palladium-catalyzed Hiyama cross-coupling of aryl trior tetrahalides with 1,3-bis[(E)-4-halostyryl] disiloxanes is described. Georg Thieme Verlag Stuttgart.
Competitive acylation of arylstyrylsilanes: Controlling silanucleophile reactivity
Brook, Michael A.,Henry, Courtney
, p. 861 - 868 (2007/10/03)
Electrophilic substitution reactions occurred cleanly between acyl cations and arylstyrylsilanes 2-4. With an unsubstituted aryl group, 2 underwent transfer of the styryl group to form styryl ketone 5 as would be predicted from previous kinetic studies. With increasing methyl group substitution of the aryl group, aryl group transfer occurred competitively such that 3 showed a 2:1 preference for destyrylation: dearylation giving 10:11 while 4 underwent exclusive transfer of the mesityl group to give mesityl ketones 6-8. These results are not consistent with electrophilic aromatic substitution reactions of nonsilylated compounds. With increasing methyl group substitution of the aryl group, its reactivity should increase for electronic reasons but not to the extent that is surpasses that of the styryl group. When the silyl group is flanked by methyl groups, however, cleavage of the silicon-aryl bond is additionally facilitated by the relief of steric congestion such that this process occurs preferentially to transfer of the styryl group.
