Palladium-free and ligand-free Sonogashira cross-coupling

Thathagar, Mehul B.; Beckers, Jurriaan; Rothenberg, Gadi

doi:10.1039/b401586j

Cited by 192 publications

(90 citation statements)

References 33 publications

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“…Our previous studies showed that Cu clusters are particularly suited to Suzuki, [18,19] and Sonogashira [20] cross-coupling reactions. In this paper, we show the use of nanometric copper clusters as efficient ligand-free catalysts for 1,3-dipolar cycloaddition reactions between azides and terminal alkynes.…”

Section: Introductionmentioning

confidence: 99%

Click Chemistry: Copper Clusters Catalyse the Cycloaddition of Azides with Terminal Alkynes

2005

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Section: Introductionmentioning

confidence: 99%

Click Chemistry: Copper Clusters Catalyse the Cycloaddition of Azides with Terminal Alkynes

2005

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“…8 With respect to catalysis by metals, Van Gelderen et al showed that silica-4 supported Cu was effective 9 as were ligand-stabilized Cu clusters. 10 Most recently, Boronat et al…”

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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“…54 More recently, it has been shown that nanoscale copper catalysts are released from copper bronze in ionic liquid media and these particles were active in the Heck reaction. 45 Further copper nanoparticle IL systems were active in well-known reactions like the Stille, 46 Sonogashira, 44 and Buchwald-Hartwig coupling. 47 Moreover, copper nanocatalysts in IL support the coupling of aryl halides with ammonia yielding anilines, 55 diaryl ethers (or thioethers) are obtained by coupling phenols with aryl halides, 40,50,53 and unexpected coupling of olefins with THF was observed.…”

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“…38,40,43 There are some reports about application of copper and copper oxide nanoparticles in ionic liquids, however most of them are related to electrochemistry and microelectronics and only very few report about application as catalysts in the wide field of organic synthesis. 37,38,40,[44][45][46][47][48][49][50][51][52][53][54] The first report about colloidal copper catalysts for the coupling of aryl halides and activated olefins was reported by Heck and Nolley in 1972. 54 More recently, it has been shown that nanoscale copper catalysts are released from copper bronze in ionic liquid media and these particles were active in the Heck reaction.…”

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Recyclable nanoscale copper(i) catalysts in ionic liquid media for selective decarboxylative C–C bond cleavage

Kessler

Gedig

Sahler

et al. 2013

Catal. Sci. Technol.

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Here we report the synthesis and application of finely divided Cu 2 O nanoparticles (Cu 2 O-NPs) in the range from 5.5 nm to 8.0 nm in phosphonium ionic liquids as the first recyclable and effective catalytic system for smooth, ligand-and additive-free protodecarboxylation of 2-nitrobenzoic acid as a model substrate and further derivatives. The reactions run with low catalyst loadings and result in quantitative yield in ten consecutive recycling experiments. In addition this system is highly selective towards electron-poor 2-nitrobenzoic acids.

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Palladium-free and ligand-free Sonogashira cross-coupling

Cited by 192 publications

References 33 publications

Click Chemistry: Copper Clusters Catalyse the Cycloaddition of Azides with Terminal Alkynes

Click Chemistry: Copper Clusters Catalyse the Cycloaddition of Azides with Terminal Alkynes

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

Recyclable nanoscale copper(i) catalysts in ionic liquid media for selective decarboxylative C–C bond cleavage

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