111185-41-2Relevant articles and documents
Salicylaldimine ruthenium alkylidene complexes: Metathesis catalysts tuned for protic solvents
Binder, Joseph B.,Guzei, Ilia A.,Raines, Ronald T.
, p. 395 - 404 (2007)
Tuning the electronic and steric environment of olefin metathesis catalysts with specialized ligands can adapt them to broader applications, including metathesis in aqueous solvents. Bidentate salicylaldimine ligands are known to stabilize ruthenium alkylidene complexes, as well as allow ringclosing metathesis in protic media. Here, we report the synthesis and characterization of exceptionally robust olefin metathesis catalysts bearing both bidentate salicylaldimine and N-heterocyclic carbene ligands, including a trimethylammonium-functionalized complex adapted for polar solvents. NMR spectroscopy and X-ray crystallographic analysis confirm the structures of the complexes. Although the N-heterocyclic carbene-salicylaldimine ligand combination limits the activity of these catalysts in non-polar solvents, this pairing enables efficient ring-closing metathesis of both dienes and enynes in methanol and methanol/water mixtures under air.
Monolithic disk-supported metathesis catalysts for use in combinatorial chemistry
Mayr, Monika,Wang, Dongren,Kroell, Roswitha,Schuler, Norbert,Pruehs, Stefan,Fuerstner, Alois,Buchmeiser, Michael R.
, p. 484 - 492 (2005)
Two metathesis catalysts, RuCl2(PCy3)-(NHC)(CHPh) (1) [NHC = 1-(2,4,5-trimethylphenyl)-3-(6-hydroxyhexyl)-imidazol-2-ylidene] and Mo(N-2,6-i-Pr2-C6H3)(CHCMe2Ph) (BIPHEN) (2) [BIPHEN = -3
Metathesis in water conducted by tailor-made encapsulated Grubbs' catalyst
Pauly, Jan,Gr?ger, Harald,Patel, Anant V.
, p. 5179 - 5187 (2018)
Metathesis in water represents a current challenge in green chemistry, since hydrophobic catalysts are non-soluble in this medium. Although this issue has been addressed by modification of the hydrophobic ligand structure, alternative methods for conducting metathesis in water are of interest, such as catalyst encapsulation. In this contribution we report successful encapsulation of the Grubbs' second-generation catalyst in alginate hydrogels, representing a renewable resource, to perform ring-closing metathesis (RCM) in water. We initially investigated the influence of different solvents on the reaction rate and confirmed that water is a preferred solvent. A comparison of non-encapsulated and encapsulated catalyst in calcium alginate revealed that the reaction rate for non-encapsulated catalyst was notably higher, which can be explained by "on water" conditions in this case. Inside the beads the encapsulated catalyst remained heterogeneous, thus allowing to switch the catalysis mode between "in/on water" through encapsulation. To overcome diffusion limitation and enhance reaction rate, we prepared a tailor-made bead material by introducing hydrophobic octyl-grafted alginate amide. Using such a hydrogel, diffusion limitation was positively influenced by hydrophobisation of the matrix, resulting in up to quadrupled reaction rates compared to calcium alginate as a standard encapsulation material. In terms of recycling, this encapsulated catalyst revealed promising performance, retaining 80% of its activity after ten runs. This is the first reported application of hydrophobised alginate derivatives in catalysed organic synthesis, achieving excellent encapsulation efficiency, no measurable leaching and yields of up to 87%.
Vortex Fluidic Ethenolysis, Integrating a Rapid Quench of Ruthenium Olefin Metathesis Catalysts
Pye, Scott J.,Chalker, Justin M.,Raston, Colin L.
, p. 1138 - 1143 (2020/08/27)
Ruthenium-catalysed ethenolysis occurs in a vortex fluidic device (VFD)-a scalable, thin-film microfluidic continuous flow process. This process takes advantage of the efficient mass transfer of gaseous reagents into the dynamic thin film of liquid. Also reported is the rapid quenching of the ruthenium-based olefin metathesis catalyst by the addition of a saturated solution of N-acetyl-l-cysteine in MeCN, as a convenient alternative to previously reported quenching methods.
Olefin metathesis in air using latent ruthenium catalysts: Imidazole substituted amphiphilic hydrogenated ROMP polymers providing nano-sized reaction spaces in water
?ztürk, Bengi ?zgün,Durmu?, Burcu,Karabulut ?ehito?lu, Solmaz
, p. 5807 - 5815 (2018/11/24)
Imidazole substituted hydrogenated amphiphilic ROMP polymers were used as both surfactants and ligand precursors for olefin metathesis reactions in water. Amphiphilic ROMP polymers were synthesized using a two-step procedure. Firstly, dimethyl-5-norbornene-2,3-dicarboxylate was polymerized using ring-opening metathesis polymerization (ROMP)/cross-metathesis (CM) in the presence of allyl-PEG5000 methyl ether and a Grubbs 3rd generation (G3) catalyst. Secondly, a one-pot hydrogenation/aminolysis protocol was used for the post-polymerization modification of PEG end-capped polynorbornene derivatives. Hydrogenation reactions were carried out using residual G3 in the presence of formic acid/sodium formate in THF at 70 °C. The aminolysis reaction was carried out without isolation of the hydrogenated polymer, using triazabicyclodecene (TBD) and 1-(3-aminopropyl)-imidazole, forming imidazole substituted hydrogenated amphiphilic ROMP polymers (mod-Amph1) in an efficient manner. G1-mod-Amph1 formed micelle structures in water with an average particle size of 85.95 (±35) nm as determined by transmission electron microscopy (TEM) and dynamic light scattering (DLS) analysis. The diffusion of Grubbs 1st generation (G1) catalyst into the micelle structure has led to the formation of nano-sized catalysts which exhibited a latent characteristic. The diffusion of hydrophobic olefinic substrates into the nano-reaction spaces, followed by activation of the catalyst with HCl led to a very efficient catalytic system for ring-closing metathesis reactions. RCM reactions of various hydrophobic dienes can run in non-degassed water under an air atmosphere. The catalyst system exhibits similar performance under an air atmosphere even in tap water, reaching a conversion value of 90% for RCM of diethyl diallylmalonate with a catalytic loading of 1% Ru.
