34106-93-9Relevant academic research and scientific papers
Indenylidene complexes of ruthenium bearing NHC ligands - structure elucidation and performance as catalysts for olefin metathesis
Monsaert, Stijn,De Canck, Els,Drozdzak, Renata,Van Voort, Pascal Der,Verpoort, Francis,Martins, Jose C.,Hendrickx, Pieter M. S.
, p. 655 - 665 (2009)
Second-generation catalysts of the general formula Cl2Ru-(SIMes) (L)(3-phenylinden-1-ylidene), 3a (L = PCy3), 3b (L =PPh3), 3c (L = py), and Cl2Ru(SIMe)(L)(3-phenylinden-1-yl-idene), 4a (L = PCy 3), 4b (L = PPh
N-heterocyclic carbene, high oxidation state molybdenum alkylidene complexes: Functional-group-tolerant cationic metathesis catalysts
Buchmeiser, Michael R.,Sen, Suman,Unold, Joerg,Frey, Wolfgang
, (2014)
We synthesized the first N-heterocyclic carbene (NHC) complexes of Schrock's molybdenum imido alkylidene bis(triflate) complexes. Unlike existing bis(triflate) complexes, the novel 16-electron complexes represent metathesis active, functional-group-tolera
N-Heterocyclic Carbene Complexes Of Metal Imido Alkylidenes And Metal OXO Alkylidenes, And The Use Of Same
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Paragraph 0181, (2017/03/21)
The invention relates to an N-heterocyclic carbene complex of general formulas I to IV (I) (II) (III) (IV), according to which A1 stands for NR2 or PR2, A2 stands for CR2 R2′, NR2, PR2, 0 or S, A3 stands for N or P, and C stands for a carbene carbon atom, ring B is an unsubstituted or a mono or poly-substituted 5 to 7-membered ring, substituents R2 and R2′ stand, inter alia, for a linear or branched C1-Cw-alkyl group and, if N and N each stand for NR2 or PR2, are the same or different, M in formulas I, II, III or IV stands for Cr, Mo or W, X 1 or X2 in formulas I to IV are the same or different and represent, inter alia, C1-C1s carboxylates and C1-C1s-alkoxides, Y is inter alia oxygen or sulphur, Z is inter alia a linear or branched C1-Cw-alkylenoxy group, and R 1 and R1′ in formulas I to IV are, inter alia, an aliphatic or aromatic group. These compounds are particularly suitable for use as catalysts for olefin metathesis reactions and have the advantage, compared to known Schrock carbene complexes, of displaying clearly increased tolerance to functional groups such as, in particular, aldehydes, secondary amines, nitriles, carboxylic acids and alcohols.
First Neutral and Cationic Tungsten Imido Alkylidene N-Heterocyclic Carbene Complexes
Imbrich, Dominik A.,Elser, Iris,Frey, Wolfgang,Buchmeiser, Michael R.
, p. 2996 - 3002 (2017/08/15)
The synthesis of W(NAr′)(NHC)(=CHR)(2,5-Me2pyr)2 (1; Ar′: 2,6-iPr2C6H3; NHC: 1,3-diisopropylimidazol-2-ylidene; 2,5-Me2pyr: 2,5-dimethylpyrrolide; R: CMe2Ph), W(NAr′)(NHC)(=CHR)(2,5-Me2pyr)(OC6F5) (2), W(NAr′)(NHC)(=CHR)(OSiPh3)2 (3), [W(NAr′)(NHC)(=CHR)(OSiPh3))(MeCN)+][B(ArF)4 ?] (4; B(ArF)4 ?: B(3,5-(CF3)2C6H3)4 ?), [W(NAr′)(NHC)(=CHR)(2,5-Me2pyr))+][B(ArF)4 ?] (5), [W(NAr′)(NHC)(=CHR)(OC6F5))(tBuCN)+][B(ArF)4 ?] (6), W(NAr′)(NHC)(=CHR)(OtBu)2 (7), [W(NAr′)(NHC)(=CHR)(OtBu)+][B(ArF)4 ?] (8), and W(NAr′)(NHC)(=CHR)(OCMe(CF3)2)2 (9) is described, and the reactivity of the complexes in olefin metathesis and cyclopolymerization is reported. The cationic complexes 4, 5, and 6 showed high productivity and activity in olefin metathesis reactions, with turnover numbers of up to 40 000 and turnover frequencies (TOF5min) of up to 31 s?1, and also substantial functional group tolerance toward esters, nitriles, alcohols, and sulfides, particularly in the cyclopolymerization of α,ω-diynes.
Molybdenum Imido Alkylidene N-Heterocyclic Carbene Complexes: Structure–Productivity Correlations and Mechanistic Insights
Buchmeiser, Michael R.,Sen, Suman,Lienert, Christina,Widmann, Laura,Schowner, Roman,Herz, Katharina,Hauser, Philipp,Frey, Wolfgang,Wang, Dongren
, p. 2710 - 2723 (2016/08/30)
The syntheses and single-crystal X-ray structures of a series of Mo–imido alkylidene N-heterocyclic carbene (NHC) complexes (1–15) and of the first complexes containing bidentate NHC-phenolate ligands (16–18) are reported. Mo(N-2,6-Me2-C6H3)((1-R-phenethyl)-3-mesitylimidazolidin-2-ylidene)(CHR)(OTf)2 (R=CMe2Ph, 1) is the first enantiomerically pure Mo–imido alkylidene NHC catalyst. With [Mo(N-2,6-Me2-C6H3)(IMes)(CHR)(CH3CN)(OTf)(CH3CN)+ B(ArF)4?] (7), turnover numbers up to 545 000 were achieved in the homometathesis (HM) of 1-octene and 1-nonene (≤95 percent E). With 7 and 1-nonene, a turnover frequency (TOF4 min) of 8860 min?1 was determined. Productivity and E/Z-selectivity were correlated with catalyst structure. For 1, Mo(N-3,5-Me2-C6H3)(IMesH2)(CHR)(OTf)2 (9) and Mo(N-3,5-Me2-C6H3)(IMes)(CHR)(OTf)2 (10), productivity was correlated with the coalescence temperature of the two triflates, determined by variable-temperature 19F NMR spectroscopy. The square-planar conformer is postulated to be the most relevant for the catalyst activation.
18-electron ruthenium phosphine sulfonate catalysts for olefin metathesis
Bashir, Oumar,Piche, Laurence,Claverie, Jerome P.
, p. 3695 - 3701 (2014/08/18)
The first instances of ruthenium alkylidene complexes based on chelating phosphine sulfonates are presented. Although these complexes are formally 18-electron complexes bearing cis phosphines and cis one-electron donors (sulfonates and chlorides), they are surprisingly active for ring-closing metathesis, cross-metathesis, and ring-opening metathesis polymerization, thus highlighting the unique potential of the sulfonate ligand in the design of a ruthenium metathesis catalyst.
[(NHC)(NHCewg)RuCl2(CHPh)] complexes with modified NHCewg ligands for efficient ring-closing metathesis leading to tetrasubstituted olefins
Sashuk, Volodymyr,Peeck, Lars H.,Plenio, Herbert
supporting information; experimental part, p. 3983 - 3993 (2010/07/04)
Imidazolium salts (NHCewg-HCl) with electronically variable substituents in the 4,5-position (H,H or C1,C1 or H,NO2 or CN 5CN) 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(NHQw8)] complexes provide the respective [(NHC)(NHCewg)RuCl2(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°C in toluene are sufficient. The complex with the best catalytic activity in such RCM reactions and the fastest initiation rate has an NHCewg group with l,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)-(NHCcwg)RuCl2(CHPh)] and [(FLNHCewg)(NHC)RuCl2(CHPh)], with a dansyl fluorophore (FL)-tagged electron-rich NHC ligand (FL-NHC) and an electron-deficient NHC ligand (FLNHCewg) 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 NHCewg ligand normally acts as the leaving group, whereas the other NHC ligand remains ligated to ruthenium.
Synthesis and RCM activity of [(NHC)(NHCewg)RuCl 2(3-phenylindenylid-1-ene)] complexes
Peeck, Lars H.,Plenio, Herbert
experimental part, p. 2761 - 2766 (2010/08/06)
[(NHC)RuCl2(3-phenylindenylid-1-ene)(py)] (1) serves as a convenient starting material for the synthesis of [(NHC)(NHCewg) RuCl2(3-phenylindenylid-1-ene)] complexes 3a-3g utilizing [AgI(NHCewg)] complexes (2) as NHC transfer reagents. The respective complexes 3 display excellent activities in RCM reactions leading to tetrasubstituted olefins. The most active precatalyst, 3f, is characterized by 3,4-dichloro and N,N′-diethyl substituents and can be obtained in 94% isolated yield. The redox potentials of complexes 3 and the crystal structure of 3g (3,4-dichloro and N,N′-diisopropyl substituents) were determined.
Diels-Alder chemistry of siloles and their transformation into cyclohex-2-ene-1,4-cis-diols
Stevens, Andrew C.,Pagenkopf, Brian L.
supporting information; experimental part, p. 3658 - 3661 (2010/10/20)
The synthesis of siloles with substitution patterns that are continuative toward natural product synthesis are described. Their reactivity in Diels-Alder chemistry was explored through thermal, Lewis acid, and high-pressure reactions. Furthermore, bicycli
Palladium-catalyzed silylene-1,3-diene [4 + 1] cycloaddition with use of (aminosilyl)boronic esters as synthetic equivalents of silylene
Ohmura, Toshimichi,Masuda, Kohei,Takase, Ichiro,Suginome, Michinori
supporting information; experimental part, p. 16624 - 16625 (2010/02/16)
(Chemical Equation Presented) Silylboronic esters bearing a dialkylamino group on the silicon atoms reacted with 1,3-dienes in the presence of a palladium catalyst to give silacyclopent-3-enes (i.e., 2,5-dihydrosiloles) in high yields via efficient silyle
