Polyisobutylene-supported N-heterocyclic carbene palladium catalysts

Bergbreiter, David E.; Su, Haw‐Lih; Koizumi, Hiroyuki; Tian, Jinying

doi:10.1016/j.jorganchem.2010.10.058

Cited by 41 publications

(36 citation statements)

References 56 publications

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“…Usually, the supported Pd‐NHCs are assessed in the Suzuki, Sonogashira, or Heck reactions. Following the early examples of polymer‐supported NHC complexes, the use of Pd‐loaded polymer‐bound NHCs in C−C coupling reactions has been reported by using polystyrene, polyethyleneglycol, polyoxazoline, polyisobutylene, and ROMP–polynorbornene matrixes . Polymeric imidazolium salts, or NHC‐coordination polymers have also been used .…”

Section: Introductionmentioning

confidence: 99%

Vinylic Addition Polynorbornene as Support for N‐Heterocyclic Carbene Palladium Complexes: Use as Reservoir of Active Homogeneous Catalytic Species in C−C Cross‐Coupling Reactions

Torre

Albéniz

2016

ChemCatChem

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A vinylic addition polynorbornene (VA‐PNB) functionalized with imidazolium groups can be used to synthesize a well‐defined supported palladium carbene complex. This complex is a suitable precatalyst for Suzuki and Negishi cross‐coupling reactions, and it can be reused. A close look at how the catalysis works reveals that palladium aggregates form on the polymer surface after the first catalytic reaction. However, they are not easily washed out and serve as a source of small amounts of homogeneous palladium active species (about 0.01% mol), which are responsible for the catalysis. The recovered polymer can be reused several times although increased induction and reaction times are observed in consecutive uses from one run to the next. The reaction was followed up by in situ IR spectroscopy by using the ν(C−Br) absorption band of the electrophile, so there is no need for an additional functional group to apply this technique.

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Section: Introductionmentioning

confidence: 99%

Vinylic Addition Polynorbornene as Support for N‐Heterocyclic Carbene Palladium Complexes: Use as Reservoir of Active Homogeneous Catalytic Species in C−C Cross‐Coupling Reactions

Torre

Albéniz

2016

ChemCatChem

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“…The catalyst was recovered in the heptane phase in this case and recycled at least ten times. [76] In this and in most systems working under biphasic conditions, it has been shown that the products can be partially extracted in the catalyst phase (heptane in this case). However, this is not a problem because it only reduces the yield of the first cycle.…”

Section: Polymer-supported Ligands For Phase Separation Recoverymentioning

confidence: 94%

Polymers for Green C–C Couplings

Albéniz

Carrera

2011

Eur J Inorg Chem

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Cleaner and environmentally more friendly cross-coupling reactions can be carried out by the use of polymers as supports. A lot of work has been devoted to attach palladium catalysts on polymers, so they can be easily separated from the reaction mixture and reused. An overview of the methods used for this purpose is given; they include the encapsulation of palladium complexes or palladium nanoparticles by polymers and the synthesis of polymeric ligands that coordinate to palladium. Polymer-supported reagents are also important

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“…40 Moreover, the preparation of a bis[(tridecafluorooctyl)imidazol-2-ylidene]palladium complex with a pyridine ligand, 41 and its use in the MizorokiHeck reaction of 4-iodotoluene and 1-octene have been described. 42 New polymeric materials containing imidazolium moieties have been synthesized via a modification of commercially available Merrifield resin, 43 or polyisobutylene (PIB) oligomers 44 by reaction with imidazole derivatives. These functionalized polymers have been employed in the preparation of NHCpalladium-supported materials, which effectively catalyzed the MizorokiHeck reaction.…”

Section: ç Mizoroki-heck Reactionmentioning

confidence: 99%

Heterocyclic Carbene–Metal-catalyzed Csp2–Csp2 and Csp–Csp2 Couplings Using Nonmetallic Substrates

Yus¹,

Pastor²

2013

Chemistry Letters

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The use of carbene ligands for transition-metal complexes has been developed in the last decades, being of special interest those carbenes derived from a nitrogen-containing heterocyclic system. An interesting variety of carbenemetal complexes has been tested in the MizorokiHeck reaction. In comparison, few examples can be found for the MatsudaHeck version of this coupling reaction. Additionally, the Sonogashira coupling has been also catalyzed with different carbenemetal catalysts. Ç IntroductionN-Heterocyclic carbenes (NHCs) have emerged in the last years as a new family of ligands with interesting electronic and structural properties.1 The combination of their strong ·-donor and poor ³-acceptor abilities results in good coordination stability and versatility. Consequently, the use of NHC ligands based on imidazolium ions and related heterocycles has appeared as an alternative to phosphanes in the design of new organometallic catalysts.2 One of the main advantages of employing NHC-based catalysts compared with phosphanebased ones is that they are far less prone to oxidation, allowing their prolonged use, and reuse. Although NHCs were presented as simple tertiary phophane mimics, they have been recognized as much more over the past decade. Therefore, NHC ligands have become an interesting alternative to other types of ligands in different cross-coupling catalytic reactions mediated by transition metals.3 Moreover, the easy introduction of chiral elements in the corresponding precursors have made chiral NHCs promising chiral ligands in metal-based asymmetric catalysis. 4 The comparison between phosphane and NHC ligands, from a mechanistic point of view, has been studied, clear differences being found.5 First, the possibility of carbene ligand dissociation is greatly reduced due to its stronger donor ability; and second, the reactivity of the NHCmetal complex is higher probably caused by the lack of back-donation from the metal to the carbene ligand. Jutand and co-workers studied the reactivity of monocarbene and bis(carbene) Pd(0) complexes toward the oxidative addition of aryl halides, concluding that the electronic and steric properties of the carbene ligand are important factors in this step of the catalytic process. 6 Among the carboncarbon coupling reactions, the activation of a CH from an alkene (MizorokiHeck reaction) or an alkyne (Sonogashira reaction) are of special interest. This highlight review describes the progress on the topic of NHC ligands for transition-metal-catalyzed coupling reactions, employing nonmetallic reagents. Thus, both different NHC precursors and NHCmetal complexes with catalytic activity in the Mizoroki Heck, MatsudaHeck, and Sonogashira reactions are compiled. Ç Mizoroki-Heck ReactionIn 1995, Herrmann and co-workers introduced the use of bis(NHC)Pd complexes as catalysts with long-term stability in the MizorokiHeck reaction.7 Indeed, the carbenes derived from imidazole stabilized the palladium complexes due to their pronounced donor properties, being more stable toward...

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Polyisobutylene-supported N-heterocyclic carbene palladium catalysts

Cited by 41 publications

References 56 publications

Vinylic Addition Polynorbornene as Support for N‐Heterocyclic Carbene Palladium Complexes: Use as Reservoir of Active Homogeneous Catalytic Species in C−C Cross‐Coupling Reactions

Vinylic Addition Polynorbornene as Support for N‐Heterocyclic Carbene Palladium Complexes: Use as Reservoir of Active Homogeneous Catalytic Species in C−C Cross‐Coupling Reactions

Polymers for Green C–C Couplings

Heterocyclic Carbene–Metal-catalyzed Csp2–Csp2 and Csp–Csp2 Couplings Using Nonmetallic Substrates

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