Recycling of homogeneous Pd catalysts using superparamagnetic nanoparticles as novel soluble supports for Suzuki, Heck, and Sonogashira cross-coupling reactions

Stevens, Philip D.; Li, Guifeng; Fan, Jinda; Yen, Max; Gao, Yong

doi:10.1039/b505424a

Cited by 361 publications

(164 citation statements)

References 37 publications

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“…In particular the use of a soluble polymer support to immobilize N-heterocyclic carbene metal complexes has often been limited to one catalytic moiety per polymer chain. [50,[54][55][56][57] One exception to this is the work by Buchmeiser et al, whose group reported the functionalization of insoluble monolithic polymer discs with a variety of ruthenium catalysts using elegant post-polymerization functionalizations. [58] In this contribution, we report the synthesis of supported NHCs using poly(norbornene) as soluble polymer support.…”

Section: Introductionmentioning

confidence: 94%

Poly(norbornene)‐Supported N‐Heterocyclic Carbenes as Ligands in Catalysis

Sommer

Weck

2006

Adv Synth Catal

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In this contribution, we present the synthesis of norbornene-supported N-heterocyclic (NHC) carbenes. These functionalized norbornenes were polymerized via ring-opening metathesis polymerization in a controlled fashion either before or after metalation with a variety of palladium and ruthenium precursors resulting in the formation of polymersupported NHC-based metal catalysts. The activities of the palladium-based catalysts in the SuzukiMiyaura, Sonogashira and Heck coupling reactions were studied in detail. In all cases, the polymeric catalysts demonstrated the same activity as their small molecule analogues. Furthermore, we carried out preliminary investigations into the stability of these catalysts using poisoning studies. A clear dependence of the stability of the polymer-supported catalysts on their palladium precursor was observed with palladium acetate-based polymeric NHC catalysts being the most stable. Finally, we have studied the reactivity of our supported NHC ruthenium complexes as catalysts for ring-closing metathesis. Again, in all cases good conversions were observed with comparable activities to other supported NHC-ruthenium catalysts. Lastly, we were able to remove the ruthenium catalysts from the solution quantitatively demonstrating the possibility of metal removal.

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Section: Introductionmentioning

confidence: 94%

Poly(norbornene)‐Supported N‐Heterocyclic Carbenes as Ligands in Catalysis

Sommer

Weck

2006

Adv Synth Catal

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“…However, the magnetic nanoparticle supported nano-Pd(0) catalysts are more active than the magnetic nanoparticle supported homogeneous catalysts using N-heterocyclic carbene-coordinated Pd complexes. [21] The lower interaction chance of reactants in the threephase reaction mixture and relatively strong electrostatic interaction might contribute to lowering the efficiency of the catalyst. [29] In addition, after 3 runs, no obvious aggregation of Pd on the support surface to form visible nanoparticles was observed; only magnetic particle cores were observed using TEM with the oxidation state of Pd(0) confirmed by XPS analysis (see Supporting Information).…”

Section: Resultsmentioning

confidence: 99%

Supported Ultra Small Palladium on Magnetic Nanoparticles Used as Catalysts for Suzuki Cross‐Coupling and Heck Reactions

et al. 2007

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Application of transition metal nanoparticles as catalysts for organic transformations has been attracting wide interest as nanoparticle-based catalytic systems might exhibit superior catalytic activities than the corresponding bulk materials. However, the main difficulty is that such small particles are almost impossible to separate by conventional means, which can lead to the blocking of filters and valves by the nanoparticle catalyst. We have conveniently prepared ultra small palladium(0) particles (less than 1 nm) on magnetic nanoparticle supports, in which immobilized auxiliaries are used as stabilizing ligands. These catalysts were active for Suzuki crosscoupling and Heck reactions giving isolated yields of 83 % and 56 %, respectively. In addition, the catalyst can be easily separated using a magnet and reused several times with sustained activity.

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“…The main synthetic routes for the preparation of substituted dihydropyridines are Hantzsch method via the cyclocondensation of an aldehyde, β-ketoester and ammonia, 9 regioselective [4+2] cycloaddition of 1-aryl-4-phenyl-1-azadienes and allenic esters for the synthesis of N-aryl-1,4-DHPs, 10 and a multi-component reaction of alkyl amines, ethyl propiolate, and benzal- Magnetic nanoparticles show a great potential as catalysts because of their large surface area and the large ratio of atoms available at the surface to perform the chemical transformation of substrates. 17,18 However, the bare Fe 3 O 4 nanoparticles have high reactivity and easily undergo degradation upon direct exposure to certain environments, leading to poor stability and dispersity. Therefore, the surface of magnetic nanoparticles should be modified to improve the dispersity and biocompatibility, which could significantly facilitate its utilization.…”

Section: Introductionmentioning

confidence: 99%

Fe3O4@SiO2-NH2 Nanocomposite as a Robust and Effective Catalyst for the One-pot Synthesis of Polysubstituted Dihydropyridines

Ghasemzadeh¹,

Abdollahi-Basir²

2016

ACSi

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A practical, simple and efficient method for the synthesis of polysubstituted dihydropyridines was described via multicomponent reactions of aldehydes, arylamines, dimethyl acetylenedicarboxylate and malononitrile/ethyl acetoacetate in the presence of Fe 3 O 4 @SiO 2 -NH 2 nanocomposites. The present methodology provides a novel and efficient method for the synthesis of dihydropyridine derivatives with some advantages, such as excellent yields, short reaction times, recoverability and low catalyst loading. The nanomagnetic catalyst could be readily recovered using an external magnet and reused several times without any significant loss in activity. The catalyst was fully characterized by FT-IR, SEM, XRD, EDX and VSM analysis.

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Recycling of homogeneous Pd catalysts using superparamagnetic nanoparticles as novel soluble supports for Suzuki, Heck, and Sonogashira cross-coupling reactions

Abstract: Recycling of homogeneous catalysts could be achieved by using magnetic nanoparticles and solid-phase beads, but nanoparticle-supported catalysis proceeded much faster than its counterpart on resins.

Cited by 361 publications

References 37 publications

Poly(norbornene)‐Supported N‐Heterocyclic Carbenes as Ligands in Catalysis

Poly(norbornene)‐Supported N‐Heterocyclic Carbenes as Ligands in Catalysis

Supported Ultra Small Palladium on Magnetic Nanoparticles Used as Catalysts for Suzuki Cross‐Coupling and Heck Reactions

Fe3O4@SiO2-NH2 Nanocomposite as a Robust and Effective Catalyst for the One-pot Synthesis of Polysubstituted Dihydropyridines

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