Efficient Synthesis of β-Aminoacrylates and β-Enaminones Catalyzed by Zn(OAc)2·2H2O

2005 ◽  
Vol 70 (11) ◽  
pp. 1943-1952 ◽  
Author(s):  
Ramandeep Kaur Vohra ◽  
Jean-Luc Renaud ◽  
Christian Bruneau
Keyword(s):  
Catalytic Activity ◽  
Lewis Acid ◽  
Primary Amines ◽  
Acid Catalysts ◽  
Efficient Synthesis ◽  
Substituted Anilines ◽  
Lewis Acid Catalysts ◽  
Mild Conditions ◽  
Good Catalytic Activity ◽  
Direct Condensation

The direct condensation of amines with β-ketoesters and β-diketones to produce functional enamine derivatives has been investigated with zinc Lewis acid catalysts. Zn(OAc)2·2H2O shows good catalytic activity and leads to a chemo- and stereoselective formation of (Z)-enamine derivatives from aliphatic primary amines and ring-substituted anilines under mild conditions.

Activation of Ethynyl-β-Ionol by Lewis Acid Catalysts: Synthesis of a Novel Branched C20 Molecule

2003 ◽  
Vol 2003 (2) ◽  
pp. 62-62 ◽  
Author(s):  
Frédéric Lamaty
Keyword(s):  
Low Temperature ◽  
Lewis Acid ◽  
Acid Catalysts ◽  
Efficient Synthesis ◽  
Lewis Acid Catalysts

A condensation C15 + C5 between ethynyl-β-ionol and a derivative of prenal was performed at low temperature in the presence of a Lewis acid. The coupling occurs at position 7 of ethynyl-β-ionol and led to the efficient synthesis of a new C20 molecule rather than the expected retinal.

scholarly journals A new class of solid Lewis acid catalysts based on interlayer expansion of layered silicates of the RUB-36 type with heteroatoms

2014 ◽  
Vol 2 (25) ◽  
pp. 9709-9717 ◽  
Author(s):  
Trees De Baerdemaeker ◽  
Hermann Gies ◽  
Bilge Yilmaz ◽  
Ulrich Müller ◽  
Mathias Feyen ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Lewis Acid ◽  
Layered Silicates ◽  
Acid Catalysts ◽  
Lewis Acid Catalysts ◽  
New Class

Interlayer expansion of the layered zeolite precursor RUB-36 in presence of an Fe source simultaneously achieved the expansion and the introduction of catalytic activity.

scholarly journals Synthesis, characterization, and properties of a benzofuran-based cage-shaped borate: photo activation of Lewis acid catalysts

2016 ◽  
Vol 52 (16) ◽  
pp. 3348-3351 ◽  
Author(s):  
Akihito Konishi ◽  
Ryosuke Yasunaga ◽  
Kouji Chiba ◽  
Makoto Yasuda
Keyword(s):  
Catalytic Activity ◽  
Lewis Acid ◽  
Light Irradiation ◽  
Lewis Acidity ◽  
Acid Catalysts ◽  
Lewis Acid Catalysts ◽  
Black Light

A benzofuran-based cage-shaped borate showed a higher degree of Lewis acidity and exhibited photo-activated catalytic activity under black-light irradiation.

scholarly journals Catalytic Allylic Chlorination of Natural Terpenic Olefins Using Supported and Nonsupported Lewis Acid Catalysts

2020 ◽  
Vol 2020 ◽  
pp. 1-8
Author(s):  
Ayoub Abdelkader Mekkaoui ◽  
Mouhsine Laayati ◽  
Hamza Orfi ◽  
Larbi El Firdoussi ◽  
Soufiane El Houssame
Keyword(s):  
Lewis Acid ◽  
High Selectivity ◽  
Acid Catalysts ◽  
Chlorination Reaction ◽  
Lewis Acid Catalysts ◽  
Short Reaction Time ◽  
Mild Conditions ◽  
Substrate Structure ◽  
Naturally Occurring ◽  
Combination System

A mild and convenient method for the allylic chlorination of naturally occurring terpenic olefins was investigated in the presence of different supported and non-supported Lewis acid catalysts. The reaction has been tested on carvone as a model substrate in the presence of sodium hypochlorite as chlorine donor. The scope and limitations of transition metal-based Lewis acid catalysts, stoichiometry, and substrate structure were evaluated. Among the iron precursors used, FeCl3 and FeCl2 provide the promise of a general approach to allylic or vinylic chlorination reaction. Various terpenic olefins were examined in the presence of FeCl3/NaOCl combination system. The catalytic chlorination proceeds under mild conditions with short reaction time and shows a high selectivity affording the corresponding chlorides in good to excellent yields.

scholarly journals Pt/CeO2 with residual chloride as reusable soft Lewis acid catalysts: application to highly efficient isomerization of allylic esters

2021 ◽  
Author(s):  
Qi-An Huang ◽  
Asahi Haruta ◽  
Yuhya Kumamoto ◽  
Haruno Murayama ◽  
Eiji Yamamoto ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Lewis Acid ◽  
High Catalytic Activity ◽  
Acid Catalysts ◽  
Lewis Acid Catalysts ◽  
X Ray ◽  
Solvent Free Conditions ◽  
Highly Dispersed ◽  
Silica Alumina ◽  
Allylic Esters

Abstract Heterogeneous acid and base catalysts play a crucial role in many important chemical processes. Hard Lewis and Brønsted acid catalysts like silica-alumina and zeolites have been widely applied in numerous reactions; however, developing reusable and active soft Lewis acid catalysts remain a challenge. Herein, we demonstrate for the first time that a highly dispersed supported platinum catalyst can act as a heterogeneous soft Lewis acid. High turnover numbers and reusability were observed in the isomerization of allylic esters under solvent-free conditions. Moreover, the as-prepared catalysts are characterized by X-ray photoelectron spectroscopy (XPS) and X-ray absorption fine structure (XAFS) analyses, revealing that the highly dispersed Pt clusters with Pt–Cl bonds play a key role in the high activity. The residual chloride anion enhances the Lewis acidity of the Pt metal center and thus improves the catalytic activity. Simultaneously, the high catalytic activity of Pt/CeO2 with residual chloride and the soft Lewis acid mechanism are also proved by density functional theory (DFT) calculations based on the model reaction.

Reprocessing Cross-linked Polyurethanes by Catalyzing Carbamate Exchange

2019 ◽  
Author(s):  
David J. Fortman ◽  
Daylan T. Sheppard ◽  
William Dichtel
Keyword(s):  
Environmental Impact ◽  
Lewis Acid ◽  
Compression Molding ◽  
Cross Linking ◽  
Acid Catalysts ◽  
Lewis Acid Catalysts ◽  
Mild Conditions ◽  
Cross Links ◽  
Synthesized Materials

<div> <div> <div> <p>The reprocessing or recycling of cross-linked polymers by incorporating dynamic covalent cross- links has the potential to increase their usable lifetimes and reduce their environmental impact. Polyurethanes (PUs) are the largest class of cross-linked polymers; however, their direct recycling into similar value materials is not well-developed. We demonstrate that several Lewis acid catalysts mediate urethane exchange selectively and under mild conditions. Incorporating these catalysts into cross-linked polyether and polyester PUs with structures similar to commercial PU thermosets gives cross-linked materials that can completely relax stress in 100 seconds at temperatures as low as 140 oC. The dynamic polymers were reprocessed via compression molding to provide materials with similar cross-linking densities to as-synthesized materials. Because these systems are based on commercially available PU monomers and inexpensive Lewis acid catalysts, we anticipate that these findings will enable the recycling of traditional thermosetting PUs. </p> </div> </div> </div>

Reprocessing Cross-linked Polyurethanes by Catalyzing Carbamate Exchange

2019 ◽  
Author(s):  
David J. Fortman ◽  
Daylan T. Sheppard ◽  
William Dichtel
Keyword(s):  
Environmental Impact ◽  
Lewis Acid ◽  
Compression Molding ◽  
Cross Linking ◽  
Acid Catalysts ◽  
Lewis Acid Catalysts ◽  
Mild Conditions ◽  
Cross Links ◽  
Synthesized Materials

<div> <div> <div> <p>The reprocessing or recycling of cross-linked polymers by incorporating dynamic covalent cross- links has the potential to increase their usable lifetimes and reduce their environmental impact. Polyurethanes (PUs) are the largest class of cross-linked polymers; however, their direct recycling into similar value materials is not well-developed. We demonstrate that several Lewis acid catalysts mediate urethane exchange selectively and under mild conditions. Incorporating these catalysts into cross-linked polyether and polyester PUs with structures similar to commercial PU thermosets gives cross-linked materials that can completely relax stress in 100 seconds at temperatures as low as 140 oC. The dynamic polymers were reprocessed via compression molding to provide materials with similar cross-linking densities to as-synthesized materials. Because these systems are based on commercially available PU monomers and inexpensive Lewis acid catalysts, we anticipate that these findings will enable the recycling of traditional thermosetting PUs. </p> </div> </div> </div>

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