Showing papers on "Norbornene published in 2006"
TL;DR: The use of metallocene complexes and related compounds as catalysts in the dimerization or oligomerization of olefins (alkenes) or terminal acetylenes (alkynes) and in the dehydrocoupling/dehydro-oligomerisation of silanes is summarized in this article.
204 citations
TL;DR: In this article, Cationic rare earth metal alkyl species, generated by the treatment of mono(cyclopentadienyl) bis(alkyl) rare earth complex with 1 equiv. of a borate compound such as [Ph3C][B(C6F5)4], act as an excellent catalyst for the polymerization and copolymerization of various olefins.
198 citations
TL;DR: In this article, an overview of recent progress regarding ethene (E) and propene (P) -norbornene (N) copolymerization with early transition metal catalysts is provided.
171 citations
TL;DR: Regioselective additions of arylsulfonamides to vinylarenes, norbornene, and cyclohexadiene were achieved using a copper-diphosphine catayst under mild reaction conditions and appear to be ligand-accelerated.
124 citations
TL;DR: In this paper, a completely saturated homopolymer containing Si(CH3)3 group (APNSi) and a copolymer containing both Si (CH3)-3 and n-hexyl side groups (ACPNHSi) were obtained in the presence of nickel-II naphthenate/methylaluminoxane catalyst system.
Abstract: Polymerization of norbornene bearing Si(CH3)3 groups in the 5-position with the opening of double bonds and its copolymerization with 5-(n-hexyl)norbornene were realized in the presence of nickel(II) naphthenate/methylaluminoxane catalyst system. The completely saturated homopolymer containing Si(CH3)3 group (APNSi) and a copolymer containing both Si(CH3)3 and n-hexyl side groups (ACPNHSi) were prepared. The polymers have molecular mass of about 300 000 and a high glass transition temperature (Tg > 340 °C). Gas permeation properties of the polymers obtained were studied. APNSi reveals unusually high gas permeation parameters, e.g., P(O2) of about 800 Barrer for different samples. This polymer also exhibits solubility controlled gas permeation: the permeability coefficients increase in the series of n-alkanes C1−C4 when the size of the penetrant increases. Free volume in addition type substituted polynorbornenes was studied using positron annihilation lifetime spectroscopy (PALS). This method indicated th...
120 citations
TL;DR: The furan ring was replaced by different heterocycles, such as pyrroles, thiophenes, oxazoles, and a 2,4-dimethoxyphenyl group; gold catalysis then delivered no phenols, but occasionally other products were obtained.
Abstract: The effect of different substituents, such as bromo, chloromethyl, hydroxymethyl, formyl, acetyl, carboxy, and acylated hydroxymethyl and ammonium groups, on the furan ring of substrates in gold-catalyzed phenol synthesis has been investigated. The furan ring was also replaced by different heterocycles, such as pyrroles, thiophenes, oxazoles, and a 2,4-dimethoxyphenyl group; gold catalysis then delivered no phenols, but occasionally other products were obtained. [Ru(3)(CO)(12)] also catalyzed the conversion of 1 at a low rate, [Os(3)(CO)(12)] failed as a catalyst, and with [Co(2)(CO)(8)] the alkyne complex 19 can be obtained, it does not lead to any phenol but reacts with norbornene to give the product of a Pauson-Khand reaction. Efforts to prepare vinylidene complexes of 1 provided the only evidence for these species; in the presence of a phosphane ligand with ruthenium an interesting deoxygenation to 22 was observed. The phenol 2 c was converted to the allyl ether, a building block for para-Claisen rearrangements, and to the aryl triflate, a building block for cross-coupling reactions.
104 citations
TL;DR: The obtained polymeric manganese and cobalt complexes were successfully used as supported catalysts for the asymmetric epoxidation of olefins and the hydrolytic kinetic resolution of epoxides, providing further proof that catalyst density and site isolation are key toward highly active and selective supported salen catalysts.
Abstract: We report a modular approach toward polymer-supported, metalated, salen catalysts. This strategy is based on the synthesis of monofunctionalized Mn- and Co-salen complexes attached to a norbornene monomer via a stable phenylene-acetylene linker. The resulting functionalized monomers can be polymerized in a controlled fashion using ring-opening metathesis polymerization. This polymerization method allows for the synthesis of copolymers, resulting in an unprecedented control over the catalyst density and catalytic-site isolation. The obtained polymeric manganese and cobalt complexes were successfully used as supported catalysts for the asymmetric epoxidation of olefins and the hydrolytic kinetic resolution of epoxides. All polymeric catalysts showed outstanding catalytic activities and selectivities comparable to the original catalysts reported by Jacobsen. Moreover, the copolymer-supported catalysts are more active and selective than their homopolymer analogues, providing further proof that catalyst density and site isolation are key toward highly active and selective supported salen catalysts.
93 citations
TL;DR: A total synthesis of cylindramide A has been completed in 19 steps with a tandem ring-opening-ring-closing-cross metathesis that converts a readily available norbornene into an advanced intermediate.
Abstract: A total synthesis of cylindramide A has been completed in 19 steps. The key step of the synthesis is a tandem ring-opening−ring-closing−cross metathesis that converts a readily available norbornene into an advanced intermediate.
92 citations
TL;DR: In this paper, the capacity of poly(5a)-based cell reached the theoretical value (109 Ah · kg -1 ) of the polymer, while poly(1, 3, and 4) gave polymers insoluble in common organic solvents in 88-100% yields.
Abstract: 2,2,6,6-Tetramethylpiperidine 1-oxyl (TEMPO)-containing N-propargylamide HC≡CCH 2 NHCO+TEMFO (1), propargyl ester HC≡CCH 2 OCO-4-TEMPO (2), phenylacetylene derivative HC≡CC 6 H 3 -3,4-(CO 2 -4-TEMPO) 2 (3), and norbornene diester monomers, NB-2,3-exo, exo-(CH 2 OCO-4-TEMPO)2 (4), NB-2,3-endo,exo-(COO-4-TEMPO) 2 (5a), NB-2,3-endo,endo-(COO-4-TEMPO)2 (5b) (NB = norbornorbornene, TEMPO = 2,2,6,6-tetramethyl-l-piperidinyloxyl) were synthesized and polymerized with rhodium and ruthenium catalysts. Monomers 2, 5a, and 5b gave polymers with number-average molecular weights of 47000-185000 in 59-100% yields, while 1, 3, and 4 gave polymers insoluble in common organic solvents in 88-100% yields. The capacities of cells fabricated with poly(1), poly(2), and poly(3) were 67, 82, and 23 Ah · kg -1 based on the weight, respectively. The capacity of poly(5a)-based cell reached the theoretical value (109 Ah · kg -1 ) of the polymer.
92 citations
TL;DR: In this article, the effects of both solvent and cocatalyst on catalytic activity in the ethylene polymerization by the (arylmido)(aryloxo)vanadium(V) complex, VCl2(N-2,6-Me 2 C 6 H 3 )(O-2 6 Me 2C 6 H3 ) (1), have been explored in detail.
Abstract: The effects of both Al cocatalyst and solvent on catalytic activity in the ethylene polymerization by the (arylmido)(aryloxo)vanadium(V) complex, VCl2(N-2,6-Me 2 C 6 H 3 )(O-2,6-Me 2 C 6 H 3 ) (1), have been explored in detail. The activity of 5.84 × 10 5 kgPE/molV-h (TOF 2.08 × 10 7 h -1 ) has been achieved by 1/EtAlCl 2 catalyst in CH 2 Cl 2 at 0°C, and the activity in toluene increased in the order: i-Bu 2 AlCl > EtAlCl 2 > Me 2 AlCl > Et 2 AlCl > Et 2 Al(OEt), AlEt 3 , AlMe 3 (negligible activities). Both aluminum alkyl cocatalyst and solvent also affected the catalytic activity and the norbornene (NBE) incorporation in the ethylene/NBE copolymerization using complex 1, whereas the NBE contents were not strongly affected by the kind of aryl oxide ligand in VCl2(N-2,6-Me 2 C 6 H 3 )(OAr) [OAr=O-2,6-Me 2 C 6 H 3 (1), O-2,6-i-Pr 2 C 6 H 3 (2), O-2,6-Ph 2 C 6 H 3 (3)].
92 citations
TL;DR: In this paper, an imidazolium salt with silver oxide forms the silver carbene complex {[Ag(C∧N)2]3I}I2 (2; C ∧N = 3-methyl-1-picolylimidazolin-2-ylidene).
TL;DR: In this article, several new bulky monophosphine-ligated methylpalladium complexes were synthesized, and the structures depended on the shape of the ligand: a mononuclear three-coordinate structure for 1a and a chloride-bridged dinuclear structure for 2b.
TL;DR: The enantioselective [2 + 2] cycloaddition of alkynes possessing an ester functionality and norbornene derivatives proceeded efficiently using a chiral rhodium catalyst.
TL;DR: CpTiCl2(N=CtBu2) exhibits both remarkable catalytic activity and efficient norbornene (NBE) incorporation for ethylene-NBE copolymerization: the NBE incorporation by Cp'TiCl 2(X) was related to the calculated coordination energy after ethylene insertion.
TL;DR: Post-ring-opening metathesis polymerization of the norbornene pendants of 1 enhances the thermal stability of the coiled assembly as well as the tubular one and disables a thermodynamic coil-to-tube transition.
Abstract: Newly designed norbornene-appended hexabenzocoronene 1 self-assembles, upon diffusion of an Et2O vapor into its CH2Cl2 solution, to form either graphitic nanocoils or nanotubes, depending on the self-assembling conditions. The coiled assembly, selectively formed at 15 °C, is a kinetic intermediate for the tubular assembly and transforms into nanotubes on standing at 25 °C. However, post-ring-opening metathesis polymerization of the norbornene pendants of 1 enhances the thermal stability of the coiled assembly as well as the tubular one and disables a thermodynamic coil-to-tube transition. The polymerized nanocoils show an electroconductivity of 1 × 10-4 S cm-1 upon doping with I2, while the nonpolymerized nanocoils are disrupted upon being doped.
TL;DR: In this paper, the synthesis of polymer-supported N-heterocyclic (NHC) carbenes with a variety of palladium and ruthenium precursors is presented.
Abstract: In this contribution, we present the synthesis of norbornene-supported N-heterocyclic (NHC) carbenes. These functionalized norbornenes were polymerized via ring-opening metathesis polymerization in a controlled fashion either before or after metalation with a variety of palladium and ruthenium precursors resulting in the formation of polymer-supported NHC-based metal catalysts. The activities of the palladium-based catalysts in the Suzuki–Miyaura, Sonogashira and Heck coupling reactions were studied in detail. In all cases, the polymeric catalysts demonstrated the same activity as their small molecule analogues. Furthermore, we carried out preliminary investigations into the stability of these catalysts using poisoning studies. A clear dependence of the stability of the polymer-supported catalysts on their palladium precursor was observed with palladium acetate-based polymeric NHC catalysts being the most stable. Finally, we have studied the reactivity of our supported NHC ruthenium complexes as catalysts for ring-closing metathesis. Again, in all cases good conversions were observed with comparable activities to other supported NHC-ruthenium catalysts. Lastly, we were able to remove the ruthenium catalysts from the solution quantitatively demonstrating the possibility of metal removal.
TL;DR: These two rare three-coordinate nickel(I) complexes exhibit paramagnetic properties as measured by their EPR and 1H NMR spectra and could polymerize norbornene to afford addition-type polynorbornene (PNB) with high molecular weight.
Abstract: Reaction of lithium salts of anilido-imine ligands bearing bulky substituentes on the nitrogen donor atoms with trans-chloro(phenyl)bis(triphenylphosphane)nickel(II) results in the formation of two rare three-coordinate nickel(I) complexes [(Ar1NCHC6H4NAr2)Ni(I)PPh3] (1: Ar1 = Ar2 = 2,6-i-Pr2C6H3; 2: Ar1 = 2,6-Me2C6H3, Ar2 = 2,6-i-Pr2C6H3). The molecular structures of complexes 1 and 2 have been confirmed by single crystal X-ray analyses. These two complexes exhibit paramagnetic properties as measured by their EPR and 1H NMR spectra. After being activated with methylaluminoxane (MAO) these complexes could polymerize norbornene to afford addition-type polynorbornene (PNB) with high molecular weight Mw (106 g mol−1), catalytic activities being high, up to 2.82 × 107 gPNB mol−1Ni h−1.
TL;DR: In this paper, a ring-opening metathesis polymerization of COD in d-limonene has been demonstrated to yield a trisubstituted alkene during chain transfer.
Abstract: d-Limonene has been utilized as a renewable solvent and chain transfer agent for the ring-opening metathesis polymerization (ROMP) of alkene macromonomers. The polymerization of various strained monomers, such as norbornene and 1,5-cyclooctadiene (COD), and low-strain monomers, such as cyclopentene, trans,trans,trans-1,5,9-cyclododecatriene and cycloheptene, have been initiated with a ruthenium carbene complex. The metathesis reactions with d-limonene resulted in decreased weight-average (Mw) molecular weight values compared to ROMP in toluene and hydrogenated d-limonene. For the ROMP of COD in d-limonene, the amount of chain transfer and chain degradation increased with increasing time (1−20 h) and temperature (23−70 °C). The formation of the trisubstituted alkene during chain transfer, as evidenced by a model compound, was characterized by 1H NMR (δ 5.14 ppm). Optimization of the reaction conditions for the ROMP of COD resulted in the synthesis of alkene macromonomers without the need for postpolymeriza...
TL;DR: Several Pd-catalyzed cyclization methods were developed, including norbornene- mediated Catellani-type reactions, a pd-caralyzed coupling reaction of aryl iodides and allyl moieties, and a tandem C-N/C-C coupling of gem-dihalovinyl systems.
Abstract: Several Pd-catalyzed cyclization methods were developed, including norbornene- mediated Catellani-type reactions, a Pd-catalyzed coupling reaction of aryl iodides and allyl moieties, and a tandem C-N/C-C coupling of gem-dihalovinyl systems. These ring-forming methods were applied to the synthesis of highly functionalized carbocyclic and heterocyclic compounds. Intermolecular Pd-catalyzed methods for synthesis of highly substituted arene compounds were also developed.
TL;DR: A facile palladium-catalyzed carbocyclization reaction of aromatic iodides, bicyclic alkenes, and benzynes to furnish various annulated 9,10-dihydrophenanthrene derivatives is described.
TL;DR: In this article, the norbornene polymerization activity of PdCl 2 units and naked Pd 2+ cations as highly active species was investigated. And the study of activation mechanism by 31 P- and 19 F-NMR together with X-ray structural data points to the formation of Pc 2 units.
Abstract: Classes of mainly nickel(ll) and palladium(ll) complexes are comparatively presented in their norbornene polymerization activity to vinyl polynorbornene when activated with methylalumoxane, MAO, tris(pentafluorophenyl)borane/triethylaluminum, B(C 6 F 5 ) 3 /AlEt 3 or even B(C 6 F 5 ) 3 alone. Classes include Ni and Pd complexes with α-dioxime ligands, salts with [PdCl 4 ] 2- and [Pd 2 Cl 6 ] 2- units, dinuclear Ni and Pd complexes with multidentate Schiff-base ligands, polynuclear Ni- and Cr/Ni-carboxylate cage complexes, and dihalo(bisphosphane) Ni and Pd complexes. The study of activation mechanism by 31 P- and 19 F-NMR together with X-ray structural data points to the formation of PdCl 2 units and naked Pd 2+ cations as highly active species.
TL;DR: In this article, the authors used nickel(II) salicylaldiminato complexes [κ2-N,O-6-C(H)N(2,6-R2C6H3)-2,4-R‘2C 6H2O}NiMe(pyridine) to obtain high molecular weight copolymers (Mn > 104 g mol-1).
Abstract: Ethylene/norbornene and ethylene/1-butene copolymerization with nickel(II) salicylaldiminato complexes [{κ2-N,O-6-C(H)N(2,6-R2C6H3)-2,4-R‘2C6H2O}NiMe(pyridine)] (1a, R = 3,5-Me2C6H3, R‘ = I; 1b, R,R‘ = 3,5-(F3C)2C6H3; 1c, R = 3,5-(F3C)2C6H3, R‘ = I; 2, R = iPr, R‘ = I) were studied in toluene as a reaction medium and in emulsion, the latter affording polymer dispersions. High molecular weight copolymers (Mn > 104 g mol-1) are formed. Incorporation of ethylene is much preferred over butene incorporation, XBu/xBu ∼0.05 under typical reaction conditions, by comparison incorporation of the strained olefin norbornene is higher, XNB/xNB ∼0.25 (X = comonomer mole fraction in polymer; x = comonomer mole fraction in reaction mixture). Dispersions contained copolymers with up to 6 mol % comonomer (12 wt % for 1-butene; 20 wt % for norbornene). Incorporation of a few mol % of norbornene strongly decreases polymer crystallinity, which enhances the film forming properties of dispersions. Microstructure analysis by 13C...
TL;DR: In this paper, the synthesis, characterization, and polymerization behaviors of iron, cobalt, chromium, copper and zinc complexes (3-7b) bearing chelating bulky 2,6-bis[1-(2,6)-diisopropylphenylimino)ethyl]pyridine ligand (1) or 2, 6-bis [1-( 2,5-ditertbutylphenymylnylnynylimin)ethyl pyridineligand (2) are reported.
Abstract: The syntheses, characterization, and ethylene and norbornene polymerization behaviors of iron, cobalt, chromium, copper and zinc complexes (3–7b) bearing chelating bulky 2,6-bis[1-(2,6-diisopropylphenylimino)ethyl]pyridine ligand (1) or 2,6-bis[1-(2,5-ditertbutylphenylimino)ethyl]pyridine ligand (2) are reported. X-ray diffraction study of the cobalt complex (4) shows the geometry of the cobalt center to be distorted trigonal bipyramid. Treatment of the iron, cobalt 2,6-bis[1-(2,5-ditertbutylphenylimino)ethyl pyridine complexes (3 and 4) with methylaluminoxane (MAO) lead to a highly active ethylene polymerization catalysts converting ethylene to highly linear polyethylene (PE), while the corresponding chromium complex (5) is disclosed as moderate catalytic activity for the polymerization of ethylene. The specific catalytic activities were evaluated at different temperature and Al/M (M = Fe, Co and Cr) ratio. In addition, the complexes 3–5 and corresponding compounds of FeCl2, CoCl2(THF)1.5 and CrCl3(THF)3 can also catalyze vinyl polymerization of norbornene activated with MAO and show good activities. However, the copper and zinc complexes (6a–7b) showed no active in ethylene and norbornene polymerization in the presence of MAO.
TL;DR: Aryl cyanides add to norbornene and norbornadiene under nickel catalysis to give (2R*,3S*)-3-aryl-2-cyanobicyclo[2.2.1]heptanes and 3-aryl 2.5-cycles in good yields.
Abstract: Aryl cyanides add to norbornene and norbornadiene under nickel catalysis to give (2R*,3S*)-3-aryl-2-cyanobicyclo[2.2.1]heptanes and (2R*,3S*)-3-aryl-2-cyanobicyclo[2.2.1]hept-5-enes in good yields ...
TL;DR: In this paper, four cationic palladium(II) α-diimine complexes were used for copolymerization of ethene with norbornene, and the copolymers were characterized using 13C NMR spectroscopy, differential scanning calorimetry, and gel permeation chromatography techniques.
TL;DR: In this paper, the authors proposed a catalysis pathway for doubly functionalized polar norbornane derivatives bearing both cyano and ester groups, using benzonorbornadiene and norbornadienes as the substrates.
TL;DR: The preparation and characterization of a series of first to fourth generation dendronized poly-(norbornenes)s are presented and the monomers were synthesized in a divergent fashion from 5-norbornene-2.
Abstract: The preparation and characterization of a series of first to fourth generation dendronized poly-(norbornene)s are presented. The monomers were synthesized in a divergent fashion from 5-norbornene-2 ...
TL;DR: In this paper, the Cp-Ni and -Pd complexes with appropriate activators have been found to induce the addition polymerization of norbomene in excellent yields, for example (Cp)Pd(allyl)/ [Ph 3 C][B(C 6 F 5 ) 4 ] gave 105120 kg-polymer/cat-mol · h at room temperature.
Abstract: In non-polar solvents such as toluene, Cp-Ni and -Pd complexes (Cp = η 5 -C 5 H 5 ) with appropriate activators have been found to induce the addition polymerization of norbomene in excellent yields, for example (Cp)Pd(allyl)/ [Ph 3 C][B(C 6 F 5 ) 4 ] gave 105120 kg-polymer/cat-mol · h at room temperature. While the Cp-Pd system was not suitable in the presence of ester-substituted norbornenes, the Cp-Ni system, for example (Cp)Ni(Cl)(PPh 3 )/AlMe 3 /B(C 6 P 5 ) 3 can copolymerize norbornene with 5-norbomene-2-carboxylic acid methyl ester in toluene to give high yields (up to 68% in 2 h at room temperature) of copolymer with variable contents of the methyl ester monomer unit (17.4-60.7 mol-%). These copolymers have high molecular weights (M n = 234100-109500) and narrow molecular weight distributions (M w /M n = 1.78-1.89). In addition, they are soluble in common organic solvents giving flexible and transparent films on casting, that show very high Tg in the range of 352.8 to 316.0 °C. The same Ni-catalyst system can also copolymerize norbornene derivatives with bulky substituents, i.e., 2-butyl-5-norbornene and 5-norbornene-2-carboxylic acid butyl ester. The Tg of these copolymers are lower (294.9-267.3 °C) than the methyl ester-based copolymers, demonstrating that the Tg of the polynorbornene copolymer film can be tailored simply by changing the alkyl group of the monomer to within the range of 352 to 267 °C.