Equilibrium Ring-Closing Metathesis

Monfette, Sébastien; Fogg, Deryn E.

doi:10.1021/cr800541y

Cited by 350 publications

(228 citation statements)

References 286 publications

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“…It is assumed that this could be caused by back biting, metathesis of the unsaturated olefinic bonds in the growing polymer chain. 18 The polymer yields with HG1 and HG2 were limited up to 76%, relatively lower than the best results with G2 under the given condition. These catalysts apparently tended to show multimodal peaks in the lower molecular weight regions on their GPC curve, especially in the case of the higher monomer/catalyst ratio of 10,000 with HG2.…”

Section: Articlementioning

confidence: 76%

Synthesis of hydrocarbon polymers containing bulky dibenzobicyclic moiety by ROMP and their characteristic optical properties

Shiotsuki

Endō

2014

J. Polym. Sci. Part A: Polym. Chem.

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The eight-membered cyclic monomer, prepared by Diels-Alder reaction of 1,5-cyclooctadiene and anthracene, polymerized via Ru-catalyzed ring-opening metathesis to efficiently afford high polymers (M n up to 631,000). Unsaturated moieties in the main chain of the obtained polymer were hydrogenated with a homogeneous ruthenium catalyst in quantitative conversion, confirmed by 1 H-NMR measurement. The self-standing membranes were provided by casting the tetrahydrofuran solutions of both nonhydrogenated and hydrogenated polymers. The obtained membranes showed high transparency in the region of >300 nm with mechanical flexibility. Thermal gravimetric analysis revealed that both nonhydrogenated and hydrogenated polymers decomposed in two stages. The first-stage decomposition starting at around 230 C was caused by retro Diels-Alder reaction forming anthracene, proven by pyrolysis gas chromatography mass spectroscopy (GC-MS) analyses. Mechanical grinding of the polymers induced the formation of anthracene in solid state, which transformed the polymer into blue-luminescent materials under UV irradiation.

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Section: Articlementioning

confidence: 76%

Synthesis of hydrocarbon polymers containing bulky dibenzobicyclic moiety by ROMP and their characteristic optical properties

Shiotsuki

Endō

2014

J. Polym. Sci. Part A: Polym. Chem.

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“…14a) that the macrocycle 47 ( Fig. 14a) undergoes (>95%) ring opening metathesis polymerization ROMP (for reviews, see [53][54][55][56]) in the presence of a Ru catalyst (Fig. 14a) and produces Fig.…”

Section: Dynamic Covalent Changes That Make Linear Molecularmentioning

confidence: 99%

Synthetic Molecular Machines and Polymer/Monomer Size Switches that Operate Through Dynamic and Non-Dynamic Covalent Changes

Stadler

Ramírez

2011

Constitutional Dynamic Chemistry

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The present chapter is focused on how synthetic molecular machines (e.g. shuttles, switches and molecular motors) and size switches (conversions between polymers and their units, i.e., conversions between relatively large and small molecules) can function through covalent changes. Amongst the interesting examples of devices herein presented are molecular motors and size switches based on dynamic covalent chemistry which is an area of constitutional dynamic chemistry.

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“…This came as a surprise as the presence of ethene in closed-vessel reactions is not favorable for RCM reactions. [24] To demonstrate the broad applicability of these complexes for the synthesis of tetrasubstituted olefins, we tested a number of additional RCM transformations (Table 1, entries 2-5, Table 2, entries 1-6, and Table 3, entries 1-3). In almost all of the test reactions, complex 5 g with N,N'-Me,iPr substituents shows the best catalytic performance.…”

Section: Rcm Reactions Utilizing [(Nhcmentioning

confidence: 99%

[(NHC)(NHC_ewg)RuCl₂(CHPh)] Complexes with Modified NHC_ewg Ligands for Efficient Ring‐Closing Metathesis Leading to Tetrasubstituted Olefins

Sashuk

Peeck

Plenio

2010

Chemistry A European J

101

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Imidazolium salts (NHC(ewg)HCl) with electronically variable substituents in the 4,5-position (H,H or Cl,Cl or H,NO(2) or CN,CN) and sterically variable substituents in the 1,3-position (Me,Me or Et,Et or iPr,iPr or Me,iPr) were synthesized and converted into the respective [AgI(NHC)(ewg)] complexes. The reactions of [(NHC)RuCl(2)(CHPh)(py)(2)] with the [AgI(NHC(ewg))] complexes provide the respective [(NHC)(NHC(ewg))RuCl(2)(CHPh)] complexes in excellent yields. The catalytic activity of such complexes in ring-closing metathesis (RCM) reactions leading to tetrasubstituted olefins was studied. To obtain quantitative substrate conversion, catalyst loadings of 0.2-0.5 mol % at 80 degrees C in toluene are sufficient. The complex with the best catalytic activity in such RCM reactions and the fastest initiation rate has an NHC(ewg) group with 1,3-Me,iPr and 4,5-Cl,Cl substituents and can be synthesized in 95 % isolated yield from the ruthenium precursor. To learn which one of the two NHC ligands acts as the leaving group in olefin metathesis reactions two complexes, [(FL-NHC)(NHC(ewg))RuCl(2)(CHPh)] and [(FL-NHC(ewg))(NHC)RuCl(2)(CHPh)], with a dansyl fluorophore (FL)-tagged electron-rich NHC ligand (FL-NHC) and an electron-deficient NHC ligand (FL-NHC(ewg)) were prepared. The fluorescence of the dansyl fluorophore is quenched as long as it is in close vicinity to ruthenium, but increases strongly upon dissociation of the respective fluorophore-tagged ligand. In this manner, it was shown for ring-opening metathesis ploymerization (ROMP) reactions at room temperature that the NHC(ewg) ligand normally acts as the leaving group, whereas the other NHC ligand remains ligated to ruthenium.

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Equilibrium Ring-Closing Metathesis

Cited by 350 publications

References 286 publications

Synthesis of hydrocarbon polymers containing bulky dibenzobicyclic moiety by ROMP and their characteristic optical properties

Synthesis of hydrocarbon polymers containing bulky dibenzobicyclic moiety by ROMP and their characteristic optical properties

Synthetic Molecular Machines and Polymer/Monomer Size Switches that Operate Through Dynamic and Non-Dynamic Covalent Changes

[(NHC)(NHC_ewg)RuCl₂(CHPh)] Complexes with Modified NHC_ewg Ligands for Efficient Ring‐Closing Metathesis Leading to Tetrasubstituted Olefins

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Equilibrium Ring-Closing Metathesis

Cited by 350 publications

References 286 publications

Synthesis of hydrocarbon polymers containing bulky dibenzobicyclic moiety by ROMP and their characteristic optical properties

Synthesis of hydrocarbon polymers containing bulky dibenzobicyclic moiety by ROMP and their characteristic optical properties

Synthetic Molecular Machines and Polymer/Monomer Size Switches that Operate Through Dynamic and Non-Dynamic Covalent Changes

[(NHC)(NHCewg)RuCl2(CHPh)] Complexes with Modified NHCewg Ligands for Efficient Ring‐Closing Metathesis Leading to Tetrasubstituted Olefins

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[(NHC)(NHC_ewg)RuCl₂(CHPh)] Complexes with Modified NHC_ewg Ligands for Efficient Ring‐Closing Metathesis Leading to Tetrasubstituted Olefins