scholarly journals Silver and gold-catalyzed multicomponent reactions

2014 ◽  
Vol 10 ◽  
pp. 481-513 ◽  
Author(s):  
Giorgio Abbiati ◽  
Elisabetta Rossi
Keyword(s):  
Lewis Acids ◽  
Multicomponent Reactions ◽  
Catalytic Systems ◽  
Gold Salts

Silver and gold salts and complexes mainly act as soft and carbophilic Lewis acids even if their use as σ-activators has been rarely reported. Recently, transformations involving Au(I)/Au(III)-redox catalytic systems have been reported in the literature. In this review we highlight all these aspects of silver and gold-mediated processes and their application in multicomponent reactions.

Merging gold catalysis, organocatalytic oxidation, and Lewis acid catalysis for chemodivergent synthesis of functionalized oxazoles from N-propargylamides

2017 ◽  
Vol 53 (75) ◽  
pp. 10366-10369 ◽  
Author(s):  
Shaoyu Mai ◽  
Changqing Rao ◽  
Ming Chen ◽  
Jihu Su ◽  
Jiangfeng Du ◽  
...  
Keyword(s):  
Transition Metal ◽  
Lewis Acid ◽  
Lewis Acids ◽  
Acid Catalysis ◽  
Gold Catalysis ◽  
One Pot ◽  
Catalytic Systems ◽  
One Pot Synthesis ◽  
The One ◽  
Cationic Gold

Novel catalytic systems consisting of cationic gold complexes, N-hydroxyphthalimide (NHPI), and transition-metal-based Lewis acids have been developed for the one-pot synthesis of functionalized oxazoles.

scholarly journals Multicomponent reactions (MCRs): a useful access to the synthesis of benzo-fused γ-lactams

2019 ◽  
Vol 15 ◽  
pp. 1065-1085 ◽  
Author(s):  
Edorta Martínez de Marigorta ◽  
Jesús M de Los Santos ◽  
Ana M Ochoa de Retana ◽  
Javier Vicario ◽  
Francisco Palacios
Keyword(s):  
Multicomponent Reactions ◽  
Raw Materials ◽  
Working Time ◽  
Catalytic Systems

Benzo-fused γ-lactam rings such as isoindolin-2-ones and 2-oxindoles are part of the structure of many pharmaceutically active molecules. They can be often synthesized by means of multicomponent approaches and recent contributions in this field are summarized in this review. Clear advantages of these methods include the efficiency in saving raw materials and working time. However, there is still a need of new catalytic systems to allow the enantioselective preparation of these heterocycles by multicomponent reactions.

scholarly journals Catalytic Acetylation of Aromatics with Metal Chlorides and Solid Acids − a Comparative Study

2017 ◽  
Vol 6 (3) ◽  
pp. 193 ◽  
Author(s):  
Paul Wilson ◽  
Mark L. Kaliya ◽  
Miron V. Landau ◽  
Moti Herskowitz
Keyword(s):  
Lewis Acid ◽  
Sulfated Zirconia ◽  
Lewis Acids ◽  
Acid Sites ◽  
Solid Acids ◽  
Catalytic Systems ◽  
Metal Chlorides ◽  
Catalytic Behaviour ◽  
Turn Over ◽  
Redox Centers

<p>Evaluation of catalytic performances of selected metal chlorides such as AlCl<sub>3</sub>, SnCl<sub>4</sub>, ZnCl<sub>2</sub>, FeCl<sub>3</sub>, InCl<sub>3</sub> and GaCl<sub>3</sub> with solid acids such as sulfated zirconia, and zeolite beta was accomplished for acetylation of anisole, toluene and naphthalene. Presence of super acidity (Lewis or Bronsted acid) is found to be indispensable for activation of substrates towards acetylation reactions. In addition, presence of redox centers would further complement with the Lewis acid sites rendering catalytic stamina against deactivation. Strength of Lewis acid basically determines the activity of the metal chlorides towards acetylation. Among the Lewis acids investigated, FeCl<sub>3</sub>, InCl<sub>3</sub> and GaCl<sub>3</sub> exhibit their catalytic behaviour mostly through redox property as is evident from the conservation of Turn over number even after first cycle. Sulfated zirconia surpasses all the acid catalysts including metal chlorides and exhibits extended catalytic activity in acetylation of anisole. The pre-eminence of sulphated zirconia over other catalytic systems is owing to the synergistic effect of Lewis and Bronsted acidity.</p>

scholarly journals Catalytic Approaches to Multicomponent Reactions: A Critical Review and Perspectives on the Roles of Catalysis

Molecules ◽  
2021 ◽  
Vol 27 (1) ◽  
pp. 132
Author(s):  
Brenno A. D. Neto ◽  
Rafael O. Rocha ◽  
Marcelo O. Rodrigues
Keyword(s):  
Solvent Effects ◽  
Critical Review ◽  
Multicomponent Reactions ◽  
Reaction Times ◽  
Multiple Roles ◽  
Reaction Pathways ◽  
Reaction Route ◽  
Catalytic Systems ◽  
Shortening Reaction ◽  
Byproduct Formation

In this review, we comprehensively describe catalyzed multicomponent reactions (MCRs) and the multiple roles of catalysis combined with key parameters to perform these transformations. Besides improving yields and shortening reaction times, catalysis is vital to achieving greener protocols and to furthering the MCR field of research. Considering that MCRs typically have two or more possible reaction pathways to explain the transformation, catalysis is essential for selecting a reaction route and avoiding byproduct formation. Key parameters, such as temperature, catalyst amounts and reagent quantities, were analyzed. Solvent effects, which are likely the most neglected topic in MCRs, as well as their combined roles with catalysis, are critically discussed. Stereocontrolled MCRs, rarely observed without the presence of a catalytic system, are also presented and discussed in this review. Perspectives on the use of catalytic systems for improved and greener MCRs are finally presented.

scholarly journals Lewis acids immobilized in ionic liquid – application for the acetal synthesis

2013 ◽  
Vol 15 (3) ◽  
pp. 78-80 ◽  
Author(s):  
Ewa Janus
Keyword(s):  
Ionic Liquid ◽  
Catalytic Activity ◽  
Lewis Acids ◽  
Metal Chloride ◽  
Triethyl Orthoformate ◽  
High Yield ◽  
Catalytic Systems ◽  
Metal Chlorides ◽  
Acetalization Reaction

Abstract Catalytic systems composed of metal chloride (InCl3, ScCl3, YCl3, YbCl3, LaCl3, BiCl3, ZnCl3 and CuCl3) and 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)-imide, [C1C4Pyrr][NTf2] as ionic liquid were prepared. Catalytic activity of all the systems were compared in acetalization reaction between cyclohexanone and triethyl orthoformate. 1,1-Diethoxycyclohexane were formed with high yield and the selectivity at 0°C within 5 minutes. Selected metal chlorides immobilized in ionic liquid were recycled 5 times without a decrease in their activities

scholarly journals N-hexylpyridinium bis(trifluoromethylsulfonyl)imide and Lewis acids — catalytic systems for Diels-Alder reaction

2011 ◽  
Vol 9 (1) ◽  
pp. 192-198 ◽  
Author(s):  
Bożena Bittner ◽  
Ewa Janus ◽  
Eugeniusz Milchert
Keyword(s):  
Ionic Liquid ◽  
Rate Constants ◽  
Lewis Acids ◽  
Reaction Rate ◽  
Alder Reaction ◽  
Diels Alder ◽  
Catalytic Systems ◽  
Reaction Rate Constants ◽  
Diels Alder Reaction ◽  
Reaction Media

AbstractA comparative study of the Diels-Alder reactions between cyclopentadiene (1) and dienophiles (2 a–c) in N-hexylpyridinium bis(trifluoromethylsulfonyl)imide in a temperature range of 20–45°C is reported. The reaction rate constants and activation energies were calculated. Moreover, the catalytic systems based on N-hexylpyridinium bis(trifluoromethylsulfonyl)imide and Lewis acids were tested as a reaction media to perform the Diels-Alder reaction. Yb, Y, Mg, Zn triflates and chlorides (0.005 to 0.1 mmol) were used as catalysts. The recycling of catalytic system consisted of YCl3 and ionic liquid was performed.

Chiral Lewis acids integrated with single-walled carbon nanotubes for asymmetric catalysis in water

Science ◽  
2018 ◽  
Vol 362 (6412) ◽  
pp. 311-315 ◽  
Author(s):  
Taku Kitanosono ◽  
Pengyu Xu ◽  
Shū Kobayashi
Keyword(s):  
Carbon Nanotubes ◽  
Asymmetric Catalysis ◽  
Lewis Acids ◽  
Single Walled Carbon Nanotubes ◽  
Synthetic Methods ◽  
Catalytic Systems ◽  
Single Walled Carbon ◽  
Straightforward Application ◽  
High Yields ◽  
Walled Carbon Nanotubes

The development of highly reactive and stereoselective catalytic systems is required not only to improve existing synthetic methods but also to invent distinct chemical reactions. Herein, a homogenized combination of nickel-based Lewis acid–surfactant-combined catalysts and single-walled carbon nanotubes is shown to exhibit substantial activity in water. In addition to the enhanced reactivity, stereoselective performance and long-term stability were demonstrated in asymmetric conjugate addition reactions of aldoximes to furnish chiral nitrones in high yields with excellent selectivities. The practical and straightforward application of the designed catalysts in water provides an expedient, environmentally benign, and highly efficient pathway to access optically active compounds.

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