scholarly journals Ruthenium-Based Catalytic Systems Incorporating a Labile Cyclooctadiene Ligand with N-Heterocyclic Carbene Precursors for the Atom-Economic Alcohol Amidation Using Amines.

2018 ◽  
Author(s):  
Cheng Chen ◽  
Yang Miao ◽  
Kimmy De Winter ◽  
Hua-Jing Wang ◽  
Patrick Demeyere ◽  
...  
Keyword(s):  
Catalytic System ◽  
Amide Bond ◽  
Catalyst Loading ◽  
Catalytic Systems ◽  
Carbene Complexes ◽  
Amide Bond Formation ◽  
Highly Active ◽  
Metal Catalyzed ◽  
Ru Species

Transition-metal-catalyzed amide bond formation from alcohols and amines is an atom-economic and eco-friendly route. Herein, we identified a highly active in situ N-heterocyclic carbene (NHC)/ruthenium (Ru) catalytic system for this amide synthesis. Various substrates, including sterically hindered ones, could be directly transformed into the corresponding amides with the catalyst loading as low as 0.25 mol%. In this system, we replaced the p-cymene ligand of the Ru source with a relatively labile cyclooctadiene (cod) ligand so as to more efficiently obtain the corresponding poly-carbene Ru species. Expectedly, the weaker cod ligand could be more easily substituted with multiple mono-NHC ligands. Further HR-MS analyses revealed that two tetra-carbene complexes were probably generated from the in situ catalytic system.

scholarly journals Ruthenium-Based Catalytic Systems Incorporating a Labile Cyclooctadiene Ligand with N-Heterocyclic Carbene Precursors for the Atom-Economic Alcohol Amidation Using Amines

Molecules ◽  
2018 ◽  
Vol 23 (10) ◽  
pp. 2413 ◽  
Author(s):  
Cheng Chen ◽  
Yang Miao ◽  
Kimmy De Winter ◽  
Hua-Jing Wang ◽  
Patrick Demeyere ◽  
...  
Keyword(s):  
Catalytic System ◽  
High Resolution Mass Spectrometry ◽  
Amide Bond ◽  
Catalyst Loading ◽  
Catalytic Systems ◽  
Amide Bond Formation ◽  
Highly Active ◽  
Metal Catalyzed ◽  
Ru Species

Transition-metal-catalyzed amide-bond formation from alcohols and amines is an atom-economic and eco-friendly route. Herein, we identified a highly active in situ N-heterocyclic carbene (NHC)/ruthenium (Ru) catalytic system for this amide synthesis. Various substrates, including sterically hindered ones, could be directly transformed into the corresponding amides with the catalyst loading as low as 0.25 mol.%. In this system, we replaced the p-cymene ligand of the Ru source with a relatively labile cyclooctadiene (cod) ligand so as to more efficiently obtain the corresponding poly-carbene Ru species. Expectedly, the weaker cod ligand could be more easily substituted with multiple mono-NHC ligands. Further high-resolution mass spectrometry (HRMS) analyses revealed that two tetra-carbene complexes were probably generated from the in situ catalytic system.

scholarly journals Highly Efficient N-Heterocyclic Carbene/Ruthenium Catalytic Systems for the Acceptorless Dehydrogenation of Alcohols to Carboxylic Acids: Effects of Ancillary and Additional Ligands

Catalysts ◽  
2019 ◽  
Vol 10 (1) ◽  
pp. 10 ◽  
Author(s):  
Wan-Qiang Wang ◽  
Hua Cheng ◽  
Ye Yuan ◽  
Yu-Qing He ◽  
Hua-Jing Wang ◽  
...  
Keyword(s):  
Transition Metal ◽  
Carboxylic Acids ◽  
Catalytic System ◽  
Efficient Manner ◽  
Catalytic Systems ◽  
Highly Efficient ◽  
Highly Active ◽  
Ru Complexes ◽  
Alcohol Dehydrogenation ◽  
Metal Catalyzed

The transition-metal-catalyzed alcohol dehydrogenation to carboxylic acids has been identified as an atom-economical and attractive process. Among various catalytic systems, Ru-based systems have been the most accessed and investigated ones. With our growing interest in the discovery of new Ru catalysts comprising N-heterocyclic carbene (NHC) ligands for the dehydrogenative reactions of alcohols, we designed and prepared five NHC/Ru complexes ([Ru]-1–[Ru]-5) bearing different ancillary NHC ligands. Moreover, the effects of ancillary and additional ligands on the alcohol dehydrogenation with KOH were thoroughly explored, followed by the screening of other parameters. Accordingly, a highly active catalytic system, which is composed of [Ru]-5 combined with an additional NHC precursor L5, was discovered, affording a variety of acid products in a highly efficient manner. Gratifyingly, an extremely low Ru loading (125 ppm) and the maximum TOF value until now (4800) were obtained.

Acceleration of Baylis-Hillman reaction using ionic liquid supported organocatalyst

2021 ◽  
Vol 08 ◽  
Author(s):  
Vivek Srivastava
Keyword(s):  
Ionic Liquid ◽  
Ionic Liquids ◽  
Reaction Rate ◽  
Reaction Medium ◽  
Catalyst Loading ◽  
Catalyst Recycling ◽  
Catalytic Systems ◽  
Heterogeneous Catalytic ◽  
Highly Active ◽  
Low Catalyst Loading

Background: Baylis-Hillman reaction suffers from the requirement of cheap starting materials, easy reaction protocol, possibility to create the chiral center in the reaction product has increased the synthetic efficacy of this reaction, and high catalyst loading, low reaction rate, and poor yield. Objective: The extensive use of various functional or non-functional ionic liquids (ILs) with organocatalyst increases the reaction rate of various organic transformations as a reaction medium and as a support to anchor the catalysts. Methods: In this manuscript, we have demonstrated the synthesis of quinuclidine-supported trimethylamine-based functionalized ionic liquid as a catalyst for the Baylis-Hillman reaction. Results: We obtained the Baylis-Hillman adducts in good, isolated yield, low catalyst loading, short reaction time, broad substrate scope, accessible product, and catalyst recycling. N-((E,3S,4R)-5-benzylidene-tetrahydro-4-hydroxy-6-oxo-2H-pyran-3-yl) palmitamide was also successfully synthesized using CATALYST-3 promoted Baylis-Hillman reaction. Conclusion: We successfully isolated the 25 types of Baylis-Hillman adducts using three different quinuclidine-supported ammonium-based ionic liquids such as Et3AmQ][BF4] (CATALYST-1), [Et3AmQ][PF6] (CATALYST-2), and [TMAAmEQ][NTf2](CATALYST-3) as new and efficient catalysts. Tedious and highly active N-((E,3S,4R)-5-benzylidene-tetrahydro-4-hydroxy-6-oxo-2H-pyran-3-yl) palmitamide derivative was also synthesized using CATALYST-3 followed by Baylis-Hillman reaction. Generally, all the responses demonstrated higher activity and yielded high competition with various previously reported homogenous and heterogeneous Catalytic systems. Easy catalyst and product recovery followed by six catalysts recycling were the added advantages of the prosed catalytic system.

scholarly journals Visible Light-Promoted Amide Bond Formation via One-Pot Nitrone in Situ Formation/Rearrangement Cascade

CCS Chemistry ◽  
2020 ◽  
pp. 2764-2771
Author(s):  
Bao-Gui Cai ◽  
Shuai-Shuai Luo ◽  
Lin Li ◽  
Lei Li ◽  
Jun Xuan ◽  
...  
Keyword(s):  
Visible Light ◽  
Bond Formation ◽  
Amide Bond ◽  
One Pot ◽  
Amide Bond Formation ◽  
In Situ Formation

scholarly journals Poly(methylhydrosiloxane) as a green reducing agent in organophosphorus-catalysed amide bond formation

2017 ◽  
Vol 15 (30) ◽  
pp. 6426-6432 ◽  
Author(s):  
Daan F. J. Hamstra ◽  
Danny C. Lenstra ◽  
Tjeu J. Koenders ◽  
Floris P. J. T. Rutjes ◽  
Jasmin Mecinović
Keyword(s):  
Carboxylic Acids ◽  
Phosphine Oxide ◽  
Bond Formation ◽  
Reducing Agent ◽  
Amide Bond ◽  
Amide Bond Formation ◽  
Amidation Reaction

In situ reduction of phosphine oxide by poly(methylhydrosiloxane) leads to efficient amidation reaction between carboxylic acids and amines.

scholarly journals Copolymerization of Ethylene and 1-Hexene Catalyzed by the Zirconocene/Al(i-Bu)3/B(C6F5)3 Catalytic System

e-Polymers ◽  
2008 ◽  
Vol 8 (1) ◽  
Author(s):  
Puyu Zhang ◽  
Yonghong Li ◽  
Yun Chai
Keyword(s):  
Molecular Weight ◽  
Catalytic Activity ◽  
Catalytic System ◽  
Catalytic Systems ◽  
Catalytic Activities

AbstractCopolymerizations of ethylene/1-hexene were conducted using different zirconocene/AlR3/B(C6F5)3 catalytic systems at 50°C. When AlEt3 was used as alkylate agent, very low copolymerization activity was observed with both bridged catalyst Et[Ind]2ZrCl2 and unbridged zirconocene Cp2ZrCl2 in-situ activated with B(C6F5)3. In appropriate Al/Zr mole ratio using Al(i-Bu)3, the catalytic activities of both zirconocene catalytic systems were similar to those of sophisticated zirconocene/methylaluminoxane(MAO) catalytic system. The catalytic activities, comonomer incorporation and molecular weight of the copolymer synthesized with Et[Ind]2ZrCl2/Al(i-Bu)3/B(C6F5)3 were higher than those obtained with Cp2ZrCl2/Al(i- Bu)3/B(C6F5)3. The effect of the concentration of 1-hexene on catalytic activity, copolymer molecular weight, and comonomer incorporation was investigated. The complicated “co-monomer effect”, together with an increase in comonomer incorporation, a decrease in the copolymer molecular weight, was found when the comonomer concentration was increased.

scholarly journals A protocol for amide bond formation with electron deficient amines and sterically hindered substrates

2016 ◽  
Vol 14 (2) ◽  
pp. 430-433 ◽  
Author(s):  
Maria E. Due-Hansen ◽  
Sunil K. Pandey ◽  
Elisabeth Christiansen ◽  
Rikke Andersen ◽  
Steffen V. F. Hansen ◽  
...  
Keyword(s):  
Elevated Temperature ◽  
Bond Formation ◽  
Amide Bond ◽  
Standard Methods ◽  
Amide Bond Formation ◽  
Amide Coupling ◽  
Sterically Hindered

A protocol for amide coupling by in situ formation of acyl fluorides and reaction with amines at elevated temperature has been developed and found to be efficient for coupling of sterically hindered substrates and electron deficient amines where standard methods failed.

ChemInform Abstract: Metal-Catalyzed Approaches to Amide Bond Formation

ChemInform ◽  
2011 ◽  
Vol 42 (48) ◽  
pp. no-no
Author(s):  
C. Liana Allen ◽  
Jonathan M. J. Williams
Keyword(s):  
Bond Formation ◽  
Amide Bond ◽  
Amide Bond Formation ◽  
Metal Catalyzed

scholarly journals Acyl azide generation and amide bond formation in continuous-flow for the synthesis of peptides

2020 ◽  
Vol 5 (4) ◽  
pp. 645-650 ◽  
Author(s):  
Alejandro Mata ◽  
Ulrich Weigl ◽  
Oliver Flögel ◽  
Pius Baur ◽  
Christopher A. Hone ◽  
...  
Keyword(s):  
Continuous Flow ◽  
Nitrous Acid ◽  
Flow System ◽  
Bond Formation ◽  
Amide Bond ◽  
Peptide Coupling ◽  
Amide Bond Formation ◽  
Acyl Azides ◽  
Acyl Azide

Acyl azides were safely generated by using nitrous acid in water and reacted in situ within a flow system. The acyl azide was efficiently extracted into the organic phase containing an amine nucleophile for a highly enantioselective peptide coupling.

Recent Advances in the Synthesis of Amides via Oxime Rearrangements and its Applications

2018 ◽  
Vol 15 (5) ◽  
pp. 666-706 ◽  
Author(s):  
Pradip Debnath
Keyword(s):  
Natural Products ◽  
Metal Catalysts ◽  
Beckmann Rearrangement ◽  
Biologically Active ◽  
Amide Bond ◽  
Catalytic Systems ◽  
Widespread Occurrence ◽  
Amide Bond Formation ◽  
Enormous Amount ◽  
Secondary Amides

Background: Amide bond formation reactions are the most important transformations in (bio)organic chemistry because of the widespread occurrence of amides in pharmaceuticals, natural products and biologically active compounds. The Beckmann rearrangement is a well-known method used for the preparation of secondary amides from ketoximes. But, most of the traditional protocols used for the Beckmann rearrangement create enormous amount of wastes. Thus, the atom economical synthesis of amides has got high priority among the chemists. However, under classical Beckmann conditions, aldoximes do not rearrange into the corresponding primary amides. Indeed, reactions of aldoximes lead to nitriles. In recent years, it has been demonstrated that the aldoxime rearrangements can be carried out efficiently and selectively with the help of metal catalysts. <p> Objective: This review focuses on the recent progress in the amides synthesis via ketoxime and aldoxime rearrangements. Applications of the rearrangements in the synthesis of heterocycles and natural products are also covered in this review. Conclusion: In the first part of the review, relevant pathways of oxime rearrangements are discussed and it is shown that several catalytic systems have been developed for the atom-economical synthesis of N-substituted amides from ketoximes. But similar reactions with aldoximes are, however, more challenging. The advances reached in the aldoxime rearrangement are also covered in this review. It is revealed that a large variety of homogeneous and heterogeneous metal catalysts have been developed to affect aldoxime rearrangements.

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