scholarly journals Ambient gold-catalyzed O-vinylation of cyclic 1,3-diketone: A vinyl ether synthesis

2013 ◽  
Vol 9 ◽  
pp. 2537-2543 ◽  
Author(s):  
Yumeng Xi ◽  
Boliang Dong ◽  
Xiaodong Shi
Keyword(s):  
Vinyl Ether ◽  
Catalytic Amount ◽  
Direct Access ◽  
Vinyl Ethers ◽  
Ether Synthesis ◽  
First Time

Gold-catalyzed O-vinylation of cyclic 1,3-diketones has been achieved for the first time, which provides direct access to various vinyl ethers. A catalytic amount of copper triflate was identified as the significant additive in promoting this transformation. Both aromatic and aliphatic alkynes are suitable substrates with good to excellent yields.

scholarly journals Characteristics and Mechanism of Vinyl Ether Cationic Polymerization in Aqueous Media Initiated by Alcohol/B(C6F5)3/Et2O

Polymers ◽  
2019 ◽  
Vol 11 (3) ◽  
pp. 500
Author(s):  
Jinghan Zhang ◽  
Yibo Wu ◽  
Kaixuan Chen ◽  
Min Zhang ◽  
Liangfa Gong ◽  
...  
Keyword(s):  
Vinyl Ether ◽  
Cationic Polymerization ◽  
Density Functional ◽  
Aqueous Media ◽  
Vinyl Ethers ◽  
Experimental Conditions ◽  
Functional Theory ◽  
Air Atmosphere ◽  
Significant Difference ◽  
First Time

Aqueous cationic polymerizations of vinyl ethers (isobutyl vinyl ether (IBVE), 2-chloroethyl vinyl ether (CEVE), and n-butyl vinyl ether (n-BVE)) were performed for the first time by a CumOH/B(C6F5)3/Et2O initiating system in an air atmosphere. The polymerization proceeded in a reproducible manner through the careful design of experimental conditions (adding initiator, co-solvents, and surfactant or decreasing the reaction temperature), and the polymerization characteristics were systematically tested and compared in the suspension and emulsion. The significant difference with traditional cationic polymerization is that the polymerization rate in aqueous media using B(C6F5)3/Et2O as a co-initiator decreases when the temperature is lowered. The polymerization sites are located on the monomer/water surface. Density functional theory (DFT) was applied to investigate the competition between H2O and alcohol combined with B(C6F5)3 for providing a theoretical basis. The effectiveness of the proposed mechanism for the aqueous cationic polymerization of vinyl ethers using CumOH/B(C6F5)3/Et2O was confirmed.

scholarly journals Successive Activation of C–H and C–O Bonds of Vinyl Ethers by a Diphosphine and Hydrido-Bridged Diiridium Complex

Inorganics ◽  
2019 ◽  
Vol 7 (10) ◽  
pp. 121
Author(s):  
Takahashi ◽  
Shimbayashi ◽  
Fujita
Keyword(s):  
Vinyl Ether ◽  
Bond Activation ◽  
Ethyl Vinyl Ether ◽  
Vinyl Ethers ◽  
Ethyl Vinyl

The reaction of [(Cp*Ir)2(μ-dmpm)(μ-H)][OTf] (2) [Cp* = η5-C5Me5, dmpm = bis(dimethylphosphino)methane] with 2,3-dihydrofuran gives [(Cp*IrH)2(μ-dmpm){μ-(2,3-dihydrofuranyl)}][OTf] (3) in an isolated yield of 70% via the C–H bond activation at the 5-position of 2,3-dihydrofuran. Complex 3 is slowly converted into [(Cp*Ir)2(μ-dmpm)(μ-C=C(H)CH2CH2OH)][OTf] (4) quantitatively via the proton-mediated C–O bond activation. The reaction of 2 with ethyl vinyl ether gives [(Cp*Ir)2(μ-dmpm)(μ-CH=CH2)][OTf] (5) in the isolated yield of 64% via the successive activation of C–H and C–O bonds.

Nickel-catalysed alkylation of C(sp3)–H bonds with alcohols: direct access to functionalised N-heteroaromatics

2018 ◽  
Vol 54 (87) ◽  
pp. 12369-12372 ◽  
Author(s):  
Mari Vellakkaran ◽  
Jagadish Das ◽  
Sourajit Bera ◽  
Debasis Banerjee
Keyword(s):  
Base Metal ◽  
Direct Access ◽  
First Time

Base-metal catalysed C(sp3)–H bond functionalisation of methyl-N-heteroaromatics with alcohols is reported for the first time.

Stereoselective Preparation of Precursors of α-C-(1→3)-Disaccharides

2005 ◽  
Vol 70 (9) ◽  
pp. 1411-1428 ◽  
Author(s):  
Petr Štěpánek ◽  
Ondřej Vích ◽  
Lukáš Werner ◽  
Ladislav Kniežo ◽  
Hana Dvořáková ◽  
...  
Keyword(s):  
Vinyl Ether ◽  
Vinyl Ethers ◽  
Chiral Catalyst ◽  
Substituted 1

The stereoselectivity of cycloaddition of sugar-containing substituted 1-(thiazol-2-yl)but-2-en-1-ones 1 and vinyl ethers was studied using the achiral vinyl ether/chiral catalyst as well as the chiral vinyl ether/achiral catalyst combinations. It has been shown that Eu(fod)3-catalyzed cycloaddition of oxadienes 1a-1e with the chiral vinyl ethers 9 and 10 affords stereoselectively almost pure cycloadducts 11a-11e and 12a-12e, respectively. The obtained cycloadducts are suitable precursors for the synthesis of α-C-(1→3)-disaccharides, containing 2-deoxy-arabino-hexopyranose moiety of D- or L-configuration.

scholarly journals Visualization of the Ludford column

2013 ◽  
Vol 721 ◽  
pp. 438-453 ◽  
Author(s):  
Oleg Andreev ◽  
Yurii Kolesnikov ◽  
André Thess
Keyword(s):  
Liquid Metals ◽  
Basic Feature ◽  
Direct Access ◽  
Experimental Procedure ◽  
Stagnant Region ◽  
Tracer Particles ◽  
Image Velocimetry ◽  
Truncated Cylinder ◽  
First Time ◽  
Flow Experiments

AbstractWhen a liquid metal flows around a truncated cylinder in the presence of a magnetic field which is parallel to the axis of the cylinder, a stagnant region develops above the cylinder. We call this region a Ludford column. The Ludford column represents the magnetohydrodynamics (MHD) analogue of the well-known Taylor columns in rotating flows. Whereas Taylor columns can be easily visualized using dye, the visualization of Ludford columns has remained elusive up to now because liquid metals are opaque. We demonstrate that this fundamental limitation of experimental MHD can be overcome by using a superconducting 5 T magnet. This facility permits us to perform MHD experiments in which the opaque liquid metals are replaced with a transparent electrolyte while maintaining the key MHD effects. We report results of a series of flow experiments in which an aqueous solution of sulphuric acid flows around a bar with square cross-section (which for simplicity shall be referred to as a cylinder). We vary the Reynolds number in the range $5\lt Re\lt 100$ and the Hartmann number in the range $0\lt Ha\lt 14$. The experimental procedure involves flow visualizations using tracer particles as well as velocity measurements using particle image velocimetry (PIV). Our experiments provide direct access to the Ludford column for the first time and reveal the spatial structure of this basic feature of MHD flows.

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