Olefin Metathesis in the Ionic Liquid 1‐Butyl‐3‐methylimidazolium Hexafluorophosphate Using a Recyclable Ru Catalyst: Remarkable Effect of a Designer Ionic Tag

Yao, Qingwei; Zhang, Yiliang

doi:10.1002/anie.200351222

Cited by 174 publications

(9 citation statements)

References 52 publications

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“…According to the ions attached directly with the neutral complexes, ionic‐pair substituents are divided into two classifications: anion‐cationic and cation‐anionic substituents. Due to the combination of different cations and anions of the catalysts with ionic‐pair substituents, their catalytic activities can be tuned in an appropriate extent . To check out the reasons for this tuneability, most of the previous papers aimed at steric and solvation effect .…”

Section: Introductionmentioning

confidence: 99%

Electronic effect of ionic‐pair substituents

Chen

Liu

et al. 2013

J of Physical Organic Chem

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For conventional organic substituents, an almost linear relationship can be established between the para Hammett constants in aqueous solutions and chemical shifts or natural population analysis charges (NPA charges). Based on these correlations, the Hammett constants of six synthesized ionic-pair substituents were estimated via the chemical shifts, which were well in agreement with the results calculated by NPA charges. The para Hammett constants of 89 different ionic-pair substituents (77 anion-cationic and 12 cation-anionic) were therefore calculated in the gas phase based on the density functional theory method. The results show that both the anion-cationic and cation-anionic substituents are electron-withdrawing groups and the different cation-anion combinations could tune the Hammett constants of the ionic-pair substituents in a range from 0.03 to 0.77.

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Section: Introductionmentioning

confidence: 99%

Electronic effect of ionic‐pair substituents

Chen

Liu

et al. 2013

J of Physical Organic Chem

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“…As a highly effective means for creating carbon−carbon bonds, olefin metathesis is a privileged reaction in the armamentarium of synthetic and polymer chemists . Readily available and highly active ruthenium catalysts 1 − 4 have popularized metathesis chemistry in organic solvents (Figure ). , On the other hand, metathesis in aqueous solvents largely remains the domain of catalysts designed expressly for use in water (Figure ). − Despite the allure of aqueous olefin metathesis for biological applications 7 and green chemistry, the synthesis of these water-soluble ligands and complexes imposes barriers to their wider use. Developing aqueous reaction conditions suitable for catalysts such as 1 − 4 is an alternative approach.…”

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confidence: 99%

Olefin Metathesis in Homogeneous Aqueous Media Catalyzed by Conventional Ruthenium Catalysts

2007

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Olefin metathesis in aqueous solvents is sought for applications in green chemistry and with the hydrophilic substrates of chemical biology, such as proteins and polysaccharides. Most demonstrations of metathesis in water, however, utilize exotic complexes. We have examined the performance of conventional catalysts in homogeneous water-organic mixtures, finding that the second-generation Hoveyda-Grubbs catalyst has extraordinary efficiency in aqueous dimethoxyethane and aqueous acetone. High (71-95%) conversions are achieved for ring-closing and cross metathesis of a variety of substrates in these solvent systems.As a highly effective means for creating carbon-carbon bonds, olefin metathesis is a privileged reaction in the armamentarium of synthetic and polymer chemists. 1 Readily available and highly active ruthenium catalysts 1-4 have popularized metathesis chemistry in organic solvents ( Figure 1). 2,3 On the other hand, metathesis in aqueous solvents largely remains the domain of catalysts designed expressly for use in water (Figure 2). 4,5,6 Despite the allure of aqueous olefin metathesis for biological applications 7 and green chemistry, 8 the synthesis of these water-soluble ligands and complexes imposes barriers to their wider use. Developing aqueous reaction conditions suitable for catalysts such as 1-4 is an alternative approach. In the initial work with well-defined catalysts in aqueous systems, Grubbs and coworkers performed ring-openingmetathesis polymerization (ROMP) with 1 in aqueous emulsions, 9 a method that allowed Kiessling and coworkers to synthesize biologically active glycopolymers. 10 For ringclosing metathesis (RCM) and cross metathesis (CM), Blechert and coworkers employed commercially-available 2 and complex 6c, a relative of commercially-available 4, in watermethanol and water-DMF mixtures. 6 Although they achieved high conversion in the ringclosure of N-tosyldiallylamine (8) in 3:1 water/methanol and 3:1 water/DMF over an extended reaction time of 12 h, these reactions were not accomplished in homogenous systems: neither the substrate nor the catalyst was dissolved completely in the aqueous phase. In most cases raines@biochem.wisc.edu. NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author Manuscript detailed in their report, the ruthenium complex was only sparingly soluble in the aqueous reaction mixture.Metathesis in homogeneous aqueous systems would likely be faster and more versatile than in these heterogeneous systems. An effective system for metathesis with commercially available catalysts in homogeneous aqueous media would not only make this chemistry more accessible, but also highlight the limitations of the standard catalysts in water, informing catalyst-design efforts. Yet, reports of the use of common metathesis catalysts in an aqueous context are limited. For these reasons, we chose to test the capabilities of catalysts 1-4 in homogeneous aqueous media, and we report the results of our exploration herein. First, we screened various organic solvents as co-s...

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“…However, in certain cases, the transition-metal catalysts are often removed from the ionic liquid catalyst solution by polar products. When this occurs it is necessary to use specially designed polar ligands to avoid catalyst leaching. 3c, To date, some efforts have been made to address this by introducing functional groups into the ionic liquid which can complex the metal centers. , Such functional groups include thiourea, thioether, and urea which were employed for the extraction of metal ions from aqueous solutions, amines, 9a, amides, phosphines,2c nitriles,2a and alkynes. , Recently, metal complexes with pending imidazolium tags have also been reported. 2b, These incorporated functional groups are sometimes play a role in the reaction. Herein, we report a new type of ionic liquid-coordinated palladium complex for the Heck reaction.…”

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confidence: 99%