scholarly journals Electrophilic bis-fluorophosphonium dications: Lewis acid catalysts from diphosphines

2015 ◽  
Vol 6 (3) ◽  
pp. 2016-2021 ◽  
Author(s):  
Michael H. Holthausen ◽  
Rashi R. Hiranandani ◽  
Douglas W. Stephan
Keyword(s):  
Lewis Acid ◽  
Lewis Acidity ◽  
Spatial Proximity ◽  
Acid Catalysts ◽  
Lewis Acid Catalysts ◽  
Acid Catalyzed

A series of electrophilic bis-fluorophosphonium dications dervied from diphosphines with naphthalene- and (oligo)methylene-linkers is presented. The resulting Lewis acidity is demonstrated to depend on the spatial proximity between the P moieties as evidenced in several Lewis acid catalyzed transformations.

Friedel–Crafts Chemistry. Part 48. Concise Synthesis of Condensed Azaheterocyclic [1,8]naphthyridinones, Azepino-, Azocino-, and Azoninoquinoline Systems via Friedel–Crafts Ring Closures

2017 ◽  
Vol 70 (10) ◽  
pp. 1082 ◽  
Author(s):  
Hassan A. K. Abd El-Aal
Keyword(s):  
Lewis Acid ◽  
Acid Catalysts ◽  
Lewis Acid Catalysts ◽  
Acid Catalyzed ◽  
Keto Analogues ◽  
Brønsted And Lewis Acid

Unprecedented construction of a novel series of quinoline heteropolycycles (tetracyclic keto-analogues of [1,8]naphthyridinones, azepino-, azocino- and azonino[2,3-b]quinolinones systems) 10a–i by Friedel–Crafts cycliacylation reactions is described. Starting heterocyclic acids precursors 3a–i were prepared from easily accessible 2-chloroquinoline-3-carbaldehyde 1 via a three different synthetic pathways. Acid-catalyzed ring closures of the resulting tosylated acids were achieved under the influence of both Brønsted and Lewis acid catalysts. The present strategy enables a straightforward synthesis to fused tetracyclic quinolinone skeletons as demonstrated by concise and atom-economical syntheses.

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 Recent Advances in the Brønsted/Lewis Acid Catalyzed Conversion of Glucose to HMF and Lactic Acid: Pathways toward Bio-Based Plastics

Catalysts ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1395
Author(s):  
Cristina Megías-Sayago ◽  
Sara Navarro-Jaén ◽  
Fabien Drault ◽  
Svetlana Ivanova
Keyword(s):  
Lactic Acid ◽  
Lewis Acid ◽  
Catalyst Design ◽  
Added Value ◽  
Present Review ◽  
Acid Catalysts ◽  
Lewis Acid Catalysts ◽  
Starting Point ◽  
Acid Catalyzed ◽  
Multifunctional Catalyst

One of the most trending topics in catalysis recently is the use of renewable sources and/or non-waste technologies to generate products with high added value. That is why, the present review resumes the advances in catalyst design for biomass chemical valorization. The variety of involved reactions and functionality of obtained molecules requires the use of multifunctional catalyst able to increase the efficiency and selectivity of the selected process. The use of glucose as platform molecule is proposed here and its use as starting point for biobased plastics production is revised with special attention paid to the proposed tandem Bronsted/Lewis acid catalysts.

Dehydrobromination of 1,1-diaryl-1,2-dibromoalkanes catalyzed by iron and iron bromides. An ion-pair-mediated reaction?

1995 ◽  
Vol 73 (1) ◽  
pp. 56-60 ◽  
Author(s):  
Angela R. Suárez ◽  
Alejandra G. Suárez ◽  
Sandra E. Martín ◽  
María R. Mazzieri
Keyword(s):  
Lewis Acid ◽  
Ion Pair ◽  
Lewis Base ◽  
Experimental Results ◽  
Chemical Hardness ◽  
Acid Catalysts ◽  
Lewis Acid Catalysts ◽  
Phenyl Rings ◽  
Acid Catalyzed

The participation of ion-paired Lewis acid/Lewis base in the dehydrohalogenations of 1,2-dibromo-1,1 -diarylalkanes catalyzed by Fe0 and by Fe(II) and Fe(III) bromides was investigated. The reactivities of the catalyst employed were correlated with their chemical hardness. The influence of para substituents on the phenyl rings of the substrates and the results obtained in Lewis-acid-catalyzed and thermal dehydrobromination of the same compounds were compared. The experimental results could not be explained in terms of a Lewis-acid-catalyzed dehydrobromination. Keywords: dehydrohalogenation, bromoalkanes, Lewis acid catalysts, ion-pair mechanism.

Homogeneously-acid catalyzed oligomerization of glycerol

2015 ◽  
Vol 17 (8) ◽  
pp. 4307-4314 ◽  
Author(s):  
N. Sayoud ◽  
K. De Oliveira Vigier ◽  
Tatiana Cucu ◽  
Bruno De Meulenaer ◽  
Zhaoyu Fan ◽  
...  
Keyword(s):  
Lewis Acid ◽  
Average Degree ◽  
Acid Catalysts ◽  
Lewis Acid Catalysts ◽  
Acid Catalyzed ◽  
Optimized Conditions ◽  
Brønsted And Lewis Acid

Here, we report the oligomerization of glycerol in the presence of various Brønsted and Lewis acid catalysts. Under optimized conditions, oligoglycerols with an average degree of oligomerization of 3.4 were selectively obtained at 80% conversion of glycerol.

Synthesis and Applications of Chiral Bicyclic Bisborane Catalysts

Synthesis ◽  
2021 ◽  
Author(s):  
Zhao-Ying Yang ◽  
Ming Zhang ◽  
Xiao-Chen Wang
Keyword(s):  
Transition Metal ◽  
Lewis Acid ◽  
Asymmetric Hydrogenation ◽  
Acid Catalysts ◽  
Frustrated Lewis Pairs ◽  
Lewis Acid Catalysts ◽  
Lewis Bases ◽  
Metal Free ◽  
Hydrogenation Reactions ◽  
Acid Catalyzed

The development of chiral borane Lewis acid catalysts opened the door for transition-metal-free catalyzed asymmetric organic reactions. Herein, we have summarized our work on the preparation of two classes of novel chiral bicyclic bisborane Lewis acid catalysts derived from C2-symmetric [3.3.0] dienes and [4.4] dienes, respectively. These catalysts not only form frustrated Lewis pairs with Lewis bases to catalyze asymmetric hydrogenation reactions but also activate Lewis basic functional groups in traditional Lewis acid catalyzed asymmetric reactions.

scholarly journals Synthesis of 3,3′-Disubstituted Indolenines Utilizing the Lewis Acid Catalyzed Alkylation of 2,3-Disubstituted Indoles with Trichloroacetimidates

Synlett ◽  
2017 ◽  
Vol 28 (17) ◽  
pp. 2335-2339 ◽  
Author(s):  
John Chisholm ◽  
Arijit Adhikari ◽  
Léa Radal
Keyword(s):  
Transition Metal ◽  
Lewis Acid ◽  
Acid Catalysts ◽  
Lewis Acid Catalysts ◽  
Reaction Conditions ◽  
Complex Molecules ◽  
Synthetic Intermediates ◽  
Acid Catalyzed ◽  
Metal Catalyzed ◽  
Effective Reaction

Trichloroacetimidates function as effective electrophiles for the selective C3-alkylation of 2,3-disubstituted indoles to provide 3,3′-disubstituted indolenines. These indolenines are common synthetic intermediates that are often utilized in the synthesis of complex molecules. Effective reaction conditions utilizing Lewis acid catalysts have been determined, and the scope of the reaction with respect to indole and imidate reaction partner has been investigated. This chemistry provides an alternative to base promoted and transition-metal-catalyzed methods that are more commonly utilized to access similar indolenines.

Catalytic Carbonyl-Olefin Metathesis of Aliphatic Ketones: Iron(III) HomoDimers as Lewis Acidic Superelectrophiles

2018 ◽  
Author(s):  
Haley Albright ◽  
Paul S. Riehl ◽  
Christopher C. McAtee ◽  
Jolene P. Reid ◽  
Jacob R. Ludwig ◽  
...  
Keyword(s):  
Lewis Acid ◽  
Olefin Metathesis ◽  
Acid Activation ◽  
Lewis Acid Catalysts ◽  
Distinct Mode ◽  
Aliphatic Ketones ◽  
Carbon Carbon Bond ◽  
Metathesis Reactions ◽  
Acid Catalyzed

<div>Catalytic carbonyl-olefin metathesis reactions have recently been developed as a powerful tool for carbon-carbon bond</div><div>formation. However, currently available synthetic protocols rely exclusively on aryl ketone substrates while the corresponding aliphatic analogs remain elusive. We herein report the development of Lewis acid-catalyzed carbonyl-olefin ring-closing metathesis reactions for aliphatic ketones. Mechanistic investigations are consistent with a distinct mode of activation relying on the in situ formation of a homobimetallic singly-bridged iron(III)-dimer as the active catalytic species. These “superelectrophiles” function as more powerful Lewis acid catalysts that form upon association of individual iron(III)-monomers. While this mode of Lewis acid activation has previously been postulated to exist, it has not yet been applied in a catalytic setting. The insights presented are expected to enable further advancement in Lewis acid catalysis by building upon the activation principle of “superelectrophiles” and broaden the current scope of catalytic carbonyl-olefin metathesis reactions.</div>

Hydrothermal synthesis of Sn-Beta zeolites in F−-free medium

2018 ◽  
Vol 5 (11) ◽  
pp. 2763-2771 ◽  
Author(s):  
Hao Xu ◽  
Xudong Wang ◽  
Peng Ji ◽  
Haihong Wu ◽  
Yejun Guan ◽  
...  
Keyword(s):  
Hydrothermal Synthesis ◽  
Lewis Acid ◽  
Crystal Size ◽  
Acid Catalysts ◽  
Free Medium ◽  
Lewis Acid Catalysts ◽  
Structure Directing Agent ◽  
Highly Active ◽  
Beta Zeolites

Sn-Beta zeolites, with high Sn content and smaller crystal size, hydrothermally synthesized in F−-free medium using N-cyclohexyl-N,N-dimethylcyclohexanaminium hydroxide as the structure-directing agent with the assistance of Na+ and seed, are highly active as Lewis acid catalysts.

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