Showing papers on "Ring-opening metathesis polymerisation published in 1999"
TL;DR: These air- and water-tolerant complexes were shown to exhibit an increased ring-closing metathesis activity at elevated temperature when compared to that of the parent complex 2 and the previously developed complex 3.
3,127 citations
TL;DR: Two N-heterocyclic carbene ligands at once may be one too many, at least if you intend to have highly active ruthenium catalysts for olefin metathesis.
Abstract: Two N-heterocyclic carbene ligands at once may be one too many, at least if you intend to have highly active ruthenium catalysts for olefin metathesis. Density functional calculations recommend the replacement of the second carbene ligand in the successful ROMP catalysts 1 by coordinatively more labile ligands as in 2 or 3. In both cases, the catalytic activity is greatly improved.
433 citations
TL;DR: Ruthenium carbene complexes 2-8 bearing one or two imidazolin-2-ylidene ligands are highly active catalysts for all types of ring closing metathesis reactions (RCM) as mentioned in this paper.
368 citations
269 citations
TL;DR: An overview of the current knowledge about rhenium-based metathesis catalysts, in particular the industrially used Re 2 O 7 /Al 2 O 3 catalyst, is given in this article.
208 citations
TL;DR: The indenylidene−imidazolylidene complexes of ruthenium (IMes)(PR3)Cl2Ru(3-phenylindenylID-1-ene) and (IPr)(PR 3)Cl 2Ru(1-en-ene), and R= Ph, Cy) were prepared and found to be efficient catalyst precursors for ring-closing metathesis.
204 citations
TL;DR: In this paper, a new heterogeneous palladium(II)-based catalyst and its homogeneous analogue and their use for Heck-type, alkyne and amine couplings are described.
Abstract: The preparation of a new heterogeneous palladium(II)-based catalyst and its homogeneous analogue and their use for Heck-type, alkyne and amine couplings are described. The heterogeneous catalytic system is based on a polymer-bound dichloropalladium di(pyrid-2-yl)amide and was prepared via ring-opening metathesis copolymerization of norborn-2-ene-5-(N,N-di(pyrid-2-yl))carbamide with 1,4,4a,5,8,8a-hexahydro-1,4,5,8-exo-endo-dimethanonaphthalene and subsequent loading of the resulting resin with palladium(II) chloride. The heterogeneous catalyst is air, moisture, and temperature stable up to 150 °C and highly active (94−99% yields) in the vinylation of aryl iodides and aryl bromides (Heck-type couplings) with turn-over numbers (TONs) of up to 210000. Even higher TON's (up to 350000) may be achieved in the arylation of alkynes. High yields (≤95%) and TONs (≤24000) may additionally be achieved in the tetrabutylammonium bromide (TBAB) assisted vinylation of aryl chlorides. Moderate yields (<65%) and TONs (<4000...
174 citations
TL;DR: Polymer supported ruthenium catalyst 8 was found to be an effective catalyst for ring closing metathesis as mentioned in this paper, and the rate of reaction and activity was comparable to that of homogeneous catalyst 1.
157 citations
TL;DR: A trans configuration and phosphane dissociation are not necessarily necessary for catalytic activity in Grubbs-type ruthenium carbene complexes as mentioned in this paper, as shown by the fact that the chelate ligand tBu2PCH2PtBu2 (dtbpm) is an active catalyst for the ring opening metathesis polymerization of norbornene and cyclopentene.
Abstract: Atrans configuration and phosphane dissociation are not necessarily prerequisites for catalytic activity in Grubbs-type ruthenium carbene complexes [(PR3)2Cl2RuCR1R2]. This is shown by the fact that the complex [(η2-dtbpm)Cl2Ru=CH−CHCMe2] (1), in which the chelate ligand tBu2PCH2PtBu2 (dtbpm) enforces a cis geometry and disfavors phosphane dissociation, is an active catalyst for the ring opening metathesis polymerization (ROMP) of norbornene [Eq. (a)] and cyclopentene.
134 citations
TL;DR: In this paper, the synthesis of mixed carbene/phosphane-and homo- and heterobimetallic rutheniumalkylidene complexes is presented. But this work is restricted to the use of rutheium-based catalysts.
120 citations
TL;DR: Cationic RuII carbene complexes with tBu2 PCH2 PtBu2 (dtbpm) as a chelating ligand, which are accessible by chloride abstraction from neutral precursors, are established as highly efficient ring opening metathesis polymerization catalysts (see scheme).
Abstract: Cationic RuII carbene complexes with tBu2 PCH2 PtBu2 (dtbpm) as a chelating ligand, which are accessible by chloride abstraction from neutral precursors [(κ2 -dtbpm)Cl2 Ru=CHR] with trimethylsilyl triflate, are established as highly efficient ring opening metathesis polymerization catalysts (see scheme). Solv=solvent.
TL;DR: In this article, the combination of N-heterocyclic carbenes and coordinatively labile ligands (phosphanes or chloro-bridged transition metals) on the ruthenium center proves not only successful regarding catalytic performance but also promising with respect to polymer properties.
TL;DR: In this article, the acyclic diene metathesis of vegetable oils utilizing Grubbs' ruthenium catalyst (Cy3P)2Cl2Ru = CHPh has been developed.
Abstract: A new process for the acyclic diene metathesis of vegetable oils utilizing Grubbs’ ruthenium catalyst (Cy3P)2Cl2Ru = CHPh has been developed. The higher molecular weight oligomers obtained can be separated from the unreacted oil and the lower molecular weight alkene by-products easily. The reaction proceeds in the absence of solvent, with very low catalyst concentrations (0.1 mole %) under moderate temperatures and low pressures. This process does not require the stringent exclusion of water and oxygen that the previous method (Me4Sn plus WCl6) required. Low pressures appear to favor polymerization by removing the alkene by-products. The metathesis reaction has been shown to be effective for many unsaturated vegetable oils, although some cases require oil pretreatment with silica gel. This process is effective on a 2–200 g scale. Chromatographic separation and characterization of metathesized soybean oil indicate that the process involves intermolecular and intramolecular carbon-carbon double-bond formation.
TL;DR: In this paper, the preparation of a polymer-supported ruthenium alkylidene metathesis catalyst is described, which is used to initiate a ring-opening metathesizing polymerization of norbornene derivatives onto a polymer support to prepare novel highloading resins for use in combinatorial chemistry.
TL;DR: In this article, a variety of polyethers were synthesized by a tandem approach incorporating ring-closing metathesis (RCM) followed by ring-opening polymerization (ROMP) using RuCl_2(=CHPh)(PCy_3)_2 (1) as an initiator.
Abstract: A variety of polyethers were synthesized by a tandem approach incorporating ring-closing metathesis (RCM) followed by ring-opening metathesis polymerization (ROMP) using RuCl_2(=CHPh)(PCy_3)_2 (1) as an initiator. Unsaturated crown ether monomers, including a 12-crown-4 analogue (3), a benzocrown ether (8), and a benzocrown ether with a pendent phenylalanine methyl ester (9), were synthesized in good yields using a lithium ion as a template and 1 as a catalyst for RCM. Saponification of 9 afforded the benzocrown phenylalanine carboxylic acid monomer 10. The ROMP of 3, 8, and 9 with 1 as an initiator yielded the homopolymers 11, 12e, and 13e, respectively. The relative concentrations of 3 to 1 were varied to produce 11 with a wide range of molecular weights (M_n from 10 900 to 206 300). Hydrogenation of 11 proceeded quantitatively to yield a saturated polyether. Monomers 8 and 9 were copolymerized with 3 to generate polymers 12a−d and 13a−d, respectively. The copolymer composition corresponded to the feed ratio of the monomers. Crown ether 10 was copolymerized with 3 at a low feed ratio to form the corresponding polyether with pendent amino acids.
TL;DR: The ring-opening metathesis polymerization (ROMP) of 2,3-difunctionalized norbornadienes and their 7-oxa analogues catalyzed by [RuCl2(p-cymene)]2 in the presence of trimethylsilyldiazomethane (TMS) was described in this paper.
Abstract: The ring-opening metathesis polymerization (ROMP) of 2,3-difunctionalized norbornadienes and their 7-oxa analogues catalyzed by [RuCl2(p-cymene)]2 in the presence of trimethylsilyldiazomethane (TMS...
Patent•
16 Jun 1999TL;DR: In this paper, a transition metal imine compound represented by general formula shown in the figure and at least one compound selected among (B-1) an organometallic compound, (B)-an organoaluminumoxy compound, and (B-) a compound which reacts with the compound (A) to form an ion pair.
Abstract: A catalyst for olefin polymerization which is highly active in olefin polymerization and with which a polyolefin having excellent properties can be produced; and a method of polymerizing an olefin using the catalyst. The catalyst comprises (A) a transition metal imine compound represented by general formula shown in the figure and (B) at least one compound selected among (B-1) an organometallic compound, (B-2) an organoaluminumoxy compound, and (B-3) a compound which reacts with the compound (A) to form an ion pair.
TL;DR: In this paper, a ring-opening metathesis with formation of graft copolymers and polymacromonomers has been used to synthesize poly(e-caprolactone) (PCL) macromers with norbornene and polymerizable derivatives.
Abstract: Poly(e-caprolactone) (PCL) macromonomers capped by a polymerizable norbornene end-group have been synthesized and (co)polymerized by ring-opening metathesis with formation of graft copolymers and polymacromonomers. α-Norbornenyl PCL macromonomers have been synthesized by ring opening polymerization (ROP) of e-caprolactone (eCL) initiated by 2-diethylaluminoxymethyl-5-norbornene. Copolymerization of these PCL macromonomers with norbornene and polymerizable derivatives has been catalyzed by the [RuCl2(p-cymene)]2 PCy3/(trimethylsilyl)diazomethane complex yielding a series of poly(norbornene)-graft-poly(e-caprolactone) copolymers. These new graft copolymers have been characterized by a set of analytical methods, i.e., SEC, 1H-NMR, FTIR, DSC, and TGA. Furthermore, PCL macromonomers have been polymerized into high molecular weight comb chains of narrow molecular weight distribution (Mw/Mn = 1.10) within high yields (90%). © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 2447–2455, 1999
TL;DR: The azabicycloalkenones 5, 6 and 7 were formed in excellent yields via ring-closing metathesis of the bis-alkenyl precursors 1, 2 and 3 as discussed by the authors.
Abstract: The azabicycloalkenones 5, 6 and 7 were formed in excellent yields via ring-closing metathesis of the bis-alkenyl precursors 1, 2 and 3.
TL;DR: In this article, a ring opening metathesis polymerization (ROMP) of norbomene was achieved using a new Ru(ID-vinylidene complex as catalyst precursor.
TL;DR: The mutual exchange of methyl groups of ethane molecules is catalyzed by a silica-supported tantalum hydride surface complex that is five times faster than the productive alkane metathesis.
Abstract: The mutual exchange of methyl groups of ethane molecules is catalyzed by a silica-supported tantalum hydride surface complex (see the schematic representation of the transition states). This process, which resembles degenerate olefin metathesis, is five times faster than the productive alkane metathesis.
TL;DR: In this paper, the combination of these two reactions in domino processes and their application to the synthesis of complex natural products is described. But less applications have been described for other metathesis types, namely cross and ring opening metatheses.
Abstract: Olefin methathesis allows for the catalytic cleavage and formation of C,C multiple bonds under mild conditions in the presence of various functional groups. Whereas ring closing metathesis has been widely used in the synthesis of cyclic olefins, less applications have been described for other metathesis types, namely cross and ring opening metathesis. The combination of these two reactions in domino processes and their application to the synthesis of complex natural products is described.
TL;DR: The dinuclear complex Cp*2Os2Br4 (Cp* = pentamethylcyclopentadienyl) and related mono(pentamethylcycledienyl)-osmium compounds are catalysts for the ring-opening metathesis polymerization (ROMP).
TL;DR: The first examples of ring-closing metathesis reactions with allylphosphonamides, vinyl phosphonamide, and vinylphosphoneates using the Grubbs ruthenium catalyst were described in this article.
TL;DR: In this article, a ring-opening metathesis polymerization of phosphazene-functionalized norbornenes was demonstrated with the use of (PCy3)2Cl2RuCHPh as catalyst (where Cy = cyclohexyl).
Abstract: Ring-opening metathesis polymerization (ROMP) of phosphazene-functionalized norbornenes was demonstrated with the use of (PCy3)2Cl2RuCHPh as catalyst (where Cy = cyclohexyl). This allowed the incor...
TL;DR: In this paper, block-co-polymers of norborn-2-ene and 7-oxanorborn-1-ene-5,6-dicarboxylate were used for the selective extraction of lanthanides.
TL;DR: The synthesis of the C1-C7 fragment of methymycin was achieved via a ring-closing olefin metathesis employing Grubb's catalyst in the presence of Ti(O i Pr) 4 as discussed by the authors.
TL;DR: A lactose-bearing norbornene imide template was poly- merized using (Cy3P)2Cl2Ru=CHPh to produce a lactOSE-substitut- ed neoglycopolymer that showed a 100-fold overall increase in inhibitory potency compared to monomeric lactose.
Abstract: A lactose-bearing norbornene imide template was poly- merized using (Cy3P)2Cl2Ru=CHPh to produce a lactose-substitut- ed neoglycopolymer. The resulting polymer showed a 100-fold overall increase in inhibitory potency (5-fold increase on a per sac- charide residue basis) compared to monomeric lactose in both a ga- lectin-binding assay and an Erythrina corallodendrum hemagglutination assay.
TL;DR: In this article, the ring-opening metathesis polymerization of norbornene monomers bearing two and three amino acid residues has been investigated and the results were obtained using Mo(CHCMe2Ph)(N-2,6-Pri2C6H3)(OR)2, [R = CMe3 1a, CMe2CF3 1b, Cme(CF3)2 1c].