Diazo Reagents in Copper(I)-Catalyzed Olefination of Aldehydes
作者:Hélène Lebel、Michaël Davi
DOI:10.1002/adsc.200800381
日期:2008.10.6
The olefination of aldehydes to synthesize unsaturated ketones, esters, amides and phosphonates using diazo reagents and triphenylphosphine in the presence of copper(I) iodide as catalyst, is described. Good to excellent E:Z selectivities as well as yields were obtained for a large variety of aliphatic, aromatic and heteroaromatic aldehydes. The reaction showed also an excellent functional group compatibility
Atomically precise palladium nanocluster catalyzed tandem oxidation processes of alcohols and phosphorous ylides: Facile access to α,β-unsaturated esters
作者:Taiping Gao、Jialei Du、Wenyan Liu、Mingxia Ren
DOI:10.1016/j.tetlet.2020.152385
日期:2020.10
mesoporous silica nanosphere supportedpalladium nanocluster was synthesized through a simple impregnation method and well characterized. The as prepared catalyst shows excellent catalytic performance in tandem oxidation process (TOP) of alcohol and phosphorous ylide, which provides an efficient access to α,β-unsaturated esters with high yields utilizes 1 atmosphere of molecular oxygen as sole oxidant
Synthesis of β-branched Morita–Baylis–Hillman-type adducts from 1,3-diaryl-2-propynyl trimethylsilyl ethers and aldehydes catalyzed by potassium tert-butoxide
作者:Kazuhiro Yoshizawa、Takayuki Shioiri
DOI:10.1016/j.tetlet.2005.11.118
日期:2006.1
1,3-Diaryl-2-propynyl trimethylsilyl ethers were easy to isomerize into the corresponding siloxyallenes using a catalytic amount of potassiumtert-butoxide under very mild conditions. The siloxyallenes reacted in situ with various aldehydes to afford Z-selective β-branched Morita–Baylis–Hillman-type adducts in a one-pot reaction after acid treatment.
Redox-Neutral Photocatalytic Cyclopropanation via Radical/Polar Crossover
作者:James P. Phelan、Simon B. Lang、Jordan S. Compton、Christopher B. Kelly、Ryan Dykstra、Osvaldo Gutierrez、Gary A. Molander
DOI:10.1021/jacs.8b05243
日期:2018.6.27
A benchtop stable, bifunctional reagent for the redox-neutral cyclopropanation of olefins has been developed. Triethylammonium bis(catecholato)iodomethylsilicate can be readily prepared on multigram scale. Using this reagent in combination with an organic photocatalyst and visible light, cyclopropanation of an array of olefins, including trifluoromethyl- and pinacolatoboryl-substituted alkenes, can
An EZ switch: The cationic species of the heteropoly compounds has a critical impact on the Z/E selectivity of the Meyer–Schuster rearrangement of propargyl alcohols (see scheme). The isolation of the thermodynamically unfavorable Z‐α,β‐unsaturatedcarbonylcompounds is notable. The high Z selectivities were obtained at a reaction temperature as high as 50 °C.
一个 EZ 开关:杂多化合物的阳离子物质对一个临界冲击ž / é炔丙基醇的迈耶-舒斯特重排反应的选择性(见方案)。分离出热力学上不利的Z -α,β-不饱和羰基化合物。在高达 50°C的反应温度下可获得较高的Z选择性。