Recent advances and applications of Glaser coupling employing greener protocols

Sindhu, Kallikkakam S.; Anilkumar, Gopinathan

doi:10.1039/c4ra02416h

Cited by 158 publications

(93 citation statements)

References 108 publications

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“…Such reactions provide important steps in a wide range of synthetic strategies for the production of, for example, fine chemicals, carbon rich materials relevant to molecular recognition, and yet others with interesting electronic and optical properties. 2 Subsequently, Hay showed that use of a Cu(I) salt with an amine solvent in the presence of O2 enabled facile homocoupling of terminal alkynes 3 whilst by working in an H2 atmosphere, Elangovan et al showed that exclusion of O2 actually inhibited Hay coupling. 4 Despite extensive investigation, uncertainties remain concerning the mechanism of the homogeneous reaction, in particular in regard to the role of the role of gaseous oxygen.…”

Section: Introductionmentioning

confidence: 99%

Critical Role of Oxygen in Silver-Catalyzed Glaser–Hay Coupling on Ag(100) under Vacuum and in Solution on Ag Particles

et al. 2017

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The essential role of oxygen in enabling heterogeneously catalyzed Glaser−Hay coupling of phenylacetylene on Ag(100) was elucidated by STM, laboratory and synchrotron photoemission, and DFT calculations. In the absence of coadsorbed oxygen, phenylacetylene formed well-ordered dense overlayers which, with increasing temperature, desorbed without reaction. In striking contrast, even at 120 K, the presence of oxygen led to immediate and complete disruption of the organic layer due to abstraction of acetylenic hydrogen with formation of a disordered mixed layer containing immobile adsorbed phenylacetylide. At higher temperatures phenylacetylide underwent Glaser−Hay coupling to form highly ordered domains of diphenyldiacetylene that eventually desorbed without decomposition, leaving the bare metal surface. DFT calculations showed that, while acetylenic H abstraction was otherwise an endothermic process, oxygen adatoms triggered a reaction-initiating exothermic pathway leading to OH(a) + phenylacetylide, consistent with the experimental observations. Moreover, it was found that, with a solution of phenylacetylene in nonane and in the presence of O 2 , Ag particles catalyzed Glaser−Hay coupling with high selectivity. Rigorous exclusion of oxygen from the reactor strongly suppressed the catalytic reaction. Interestingly, too much oxygen lowers the selectivity toward diphenyldiacetylene. Thus, vacuum studies and theoretical calculations revealed the key role of oxygen in the reaction mechanism, subsequently borne out by catalytic studies with Ag particles that confirmed the presence of oxygen as a necessary and sufficient condition for the coupling reaction to occur. The direct relevance of model studies to a mechanistic understanding of coupling reactions under conditions of practical catalysis was reaffirmed.

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Section: Introductionmentioning

confidence: 99%

Critical Role of Oxygen in Silver-Catalyzed Glaser–Hay Coupling on Ag(100) under Vacuum and in Solution on Ag Particles

et al. 2017

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“… The representative heterogeneous catalysts covered Amberlyst A‐21 supported CuI, CuNPs@ZnO–PTh, CuO/Fe 2 O 3 NPs, nano Cu 2 O–ZnO . No matter A 3 or KA 2 couplings, a terminal alkyne is a common reactant partner which occasionally produces the Glaser‐Hay homocoupling by‐product in the presence of some kind of metal catalytic systems resulting in decreasing the yield of the propargylamine product . To address these issues, the decarboxylative coupling reaction of an aryl aldehyde, an alkynyl carboxylic acid, and an amine (decarboxylative A 3 ) is a practical variant.…”

Section: Introductionmentioning

confidence: 99%

Cu^II@PAA/PVC mesoporous fibers: A hybrid wedding as a high‐performance versatile heterogeneous catalyst for A₃, KA₂, and decarboxylative A₃ reactions

Jiang

Zhou

Sun

et al. 2020

Applied Organom Chemis

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Efforts made on the development of a novel, simple, cost‐effective, and efficient approach to fabricate a copper catalyst immobilized on mesoporous poly (acrylic acid)/poly (vinyl chloride) hybrid fibers (CuII@PAA/PVC) for versatile catalytic applications in A3, KA2, and decarboxylative A3 couplings has been described in this present work. The characterization of the mesoporous hybrid fibers was well performed by BET, FTIR, SEM, EDX, XPS, and TGA techniques. The pore structure and surface area were calculated by using BET measurement analysis. The obtained mesoporous CuII@PAA/PVC fibers exert high catalytic performance in the synthesis of propargylamines via one‐pot A3, KA2, and decarboxylative A3 reactions over a series of substrates without employing expensive ligands or inert atmosphere. The active Cu2+ species chelating with carboxylate groups in PAA/PVC hybrid fibers plays a key role in the catalysis. Meanwhile, the unique mesoporous structure and fiber morphology facilitate a better mass transfer and enlarge its contact area with substrates in the course of a reaction. Moreover, the Cu2+–carboxylate chelation could suppress the leaching of active Cu2+ species from the catalyst and thus lead to the catalyst has excellent performance and good durability as well as reusability.

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“…[6-10] The reaction is usually performed with Cu or Pd as the catalyst and organic base under heated condition in organic solvents, which are not environmentally friendly. [11][12][13][14][15] An environmentally friendly, efficient and solvent-free method for the terminal alkyne homocoupling reaction was reported in 2010. [7] The terminal alkyne can be totally transformed at 60℃ after 6 h with catalytic amounts of Cu(II) salt and base.…”

Section: Introductionmentioning

confidence: 99%

Silica/chitosan core–shell hybrid-microsphere-supported CuI catalyst for terminal alkyne homocoupling reaction

Zhao¹,

Xu²,

Wang³

2015

Applied Catalysis A: General

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Recent advances and applications of Glaser coupling employing greener protocols

Abstract: Recent developments in Glaser coupling catalysed by copper(i) is discussed in the review with emphasis on its application.

Cited by 158 publications

References 108 publications

Critical Role of Oxygen in Silver-Catalyzed Glaser–Hay Coupling on Ag(100) under Vacuum and in Solution on Ag Particles

Critical Role of Oxygen in Silver-Catalyzed Glaser–Hay Coupling on Ag(100) under Vacuum and in Solution on Ag Particles

Cu^II@PAA/PVC mesoporous fibers: A hybrid wedding as a high‐performance versatile heterogeneous catalyst for A₃, KA₂, and decarboxylative A₃ reactions

Silica/chitosan core–shell hybrid-microsphere-supported CuI catalyst for terminal alkyne homocoupling reaction

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Recent advances and applications of Glaser coupling employing greener protocols

Abstract: Recent developments in Glaser coupling catalysed by copper(i) is discussed in the review with emphasis on its application.

Cited by 158 publications

References 108 publications

Critical Role of Oxygen in Silver-Catalyzed Glaser–Hay Coupling on Ag(100) under Vacuum and in Solution on Ag Particles

Critical Role of Oxygen in Silver-Catalyzed Glaser–Hay Coupling on Ag(100) under Vacuum and in Solution on Ag Particles

CuII@PAA/PVC mesoporous fibers: A hybrid wedding as a high‐performance versatile heterogeneous catalyst for A3, KA2, and decarboxylative A3 reactions

Silica/chitosan core–shell hybrid-microsphere-supported CuI catalyst for terminal alkyne homocoupling reaction

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Cu^II@PAA/PVC mesoporous fibers: A hybrid wedding as a high‐performance versatile heterogeneous catalyst for A₃, KA₂, and decarboxylative A₃ reactions