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Showing papers on "Norbornene published in 2016"


Journal ArticleDOI
TL;DR: A synthetic methodology is discovered that combines selective C-H bond activation with sequential reactions that enables the selective functionalization of both the ortho and ipso positions of aryl halides and relates to alkylation and arylation reactions.
Abstract: ConspectusDirect C–H bond activation is an important reaction in synthetic organic chemistry. This methodology has the potential to simplify reactions by avoiding the use of prefunctionalized reagents. However, selectivity, especially site selectivity, remains challenging. Sequential reactions, in which different molecules or groups are combined in an ordered sequence, represent a powerful tool for the construction of complex molecules in a single operation.We have discovered and developed a synthetic methodology that combines selective C–H bond activation with sequential reactions. This procedure, which is now known as the “Catellani reaction”, enables the selective functionalization of both the ortho and ipso positions of aryl halides. The desired molecules are obtained with high selectivity from a pool of simple precursors. These molecules are assembled under the control of a palladacycle, which is formed through the joint action of a metal (Pd) and an olefin such as norbornene. These two species act c...

427 citations


Journal ArticleDOI
TL;DR: Both the identification of a monoprotected 3-amino-2-hydroxypyridine/pyridone-type ligand and the use of a modified norbornene as a mediator are crucial for the realization of these two unprecedented meta-C-H transformations.
Abstract: Using a modified norbornene (methyl bicyclo[2.2.1]hept-2-ene-2-carboxylate) as a transient mediator, meta-C–H amination and meta-C–H alkynylation of aniline and phenol substrates have been developed for the first time. Both the identification of a monoprotected 3-amino-2-hydroxypyridine/pyridone-type ligand and the use of a modified norbornene as a mediator are crucial for the realization of these two unprecedented meta-C–H transformations. A variety of substrates are compatible with both meta-C–H amination and meta-C–H alkynylation. Amination and alkynylation of heterocyclic substrates including indole, indoline, and indazole afford the desired products in moderate to high yields.

149 citations


Journal ArticleDOI
TL;DR: The first example of cooperative catalysis by palladium, norbornene, and copper, wherein the C(O)-S bond of thioesters is cleaved by a Pd(II) palladacycle with the assistance of CuI, has been observed.
Abstract: A Pd/norbornene/Cu cooperative catalysis for the efficient synthesis of 2-(arylthio)aryl ketones from aryl halides and thioesters has been developed. The first example of cooperative catalysis by palladium, norbornene, and copper, wherein the C(O)-S bond of thioesters is cleaved by a Pd(II) palladacycle with the assistance of CuI, has been observed.

127 citations


Journal ArticleDOI
Hang Shi1, Peng Wang1, Shin Suzuki1, Marcus E. Farmer1, Jin-Quan Yu1 
TL;DR: Pd-catalyzed meta-C-H chlorination of anilines and phenols is developed using norbornene as the mediator using heterocycles, including indole, thiophene, and indazole, and the identification of a new pyridone-based ligand is crucial.
Abstract: Pd-catalyzed meta-C–H chlorination of anilines and phenols is developed using norbornene as the mediator. Heterocycles, including indole, thiophene, and indazole, are tolerated. The identification of a new pyridone-based ligand is crucial for the success of this meta-C–H chlorination reaction. Subsequent diverse transformations of the chlorinated products demonstrate the versatility of meta-C–H chlorination.

91 citations


Journal ArticleDOI
TL;DR: A palladium-catalyzed, norbornene-mediated tandem amination/cyanation reaction via Catellani-type C-H functionalization was developed using N-benzoyloxyamines as the amination reagent and Zn(CN)2 as the terminating agent.

69 citations


Journal ArticleDOI
TL;DR: Complex 2 is the first catalyst to polymerize norbornene via ring expansion metathesis polymerization to yield highly cis-syndiotactic cyclic polynorbornene.
Abstract: The tungsten alkylidyne [tBuOCO]W≡C(tBu) (THF)2 (1) reacts with CO2, leading to complete cleavage of one C═O bond, followed by migratory insertion to generate the tungsten-oxo alkylidene 2. Complex 2 is the first catalyst to polymerize norbornene via ring expansion metathesis polymerization to yield highly cis-syndiotactic cyclic polynorbornene.

68 citations


Journal ArticleDOI
13 Oct 2016-Chem
TL;DR: A distinct method for preparing aryl carboxylic acid derivatives through ortho -alkoxycarbonylation of aryL iodides via palladium/norbornene catalysis, enabled by a carefully tuned mixed-anhydride reagent, which exhibits a board substrate scope and high functional-group compatibility.

65 citations


Journal ArticleDOI
TL;DR: Comparison of the intrinsic viscosity, radius of gyration, and elution time of the synthesized cyclic polynorbornene with those of linear analogues provides conclusive evidence for a cyclic topology.
Abstract: Tungsten alkylidynes [CF3–ONO]W≡CC(CH3)3(THF)2 (1) and [tBuOCO]W≡CC(CH3)3(THF)2 (3) react with ethylene. Complex 1 reacts reversibly with ethylene to give the metallacyclobutene (2). Complex 3 reacts with ethylene to form the tethered alkylidene (4) featuring a tetraanionic pincer ligand. Complexes 1 and 3 initiate the polymerization of norbornene at room temperature. The polymerization of norbornene by 1 is not stereoselective, whereas 3 generates a highly cis and syndiotactic cyclic polynorbornene. Comparison of the intrinsic viscosity, radius of gyration, and elution time of the synthesized cyclic polynorbornene with those of linear analogues provides conclusive evidence for a cyclic topology.

62 citations


Journal ArticleDOI
TL;DR: Ring-opening metathesis polymerization (ROMP) of various cyclic olefins especially using three (arylimido)vanadium(V)-alkylidene catalysts using dichlorophenylimido analogues were effective for ROMPs of various norbornene derivatives.
Abstract: Ring-opening metathesis polymerization (ROMP) of various cyclic olefins especially using three (arylimido)vanadium(V)-alkylidene catalysts, V(CHSiMe3)(N-2,6-Cl2C6H3) (OC6F5) (PMe3)2 (3), V(CHSiMe3) (NR)[OC(CF3)3](PMe3)2 [R = Ph (6), 2,6-Cl2C6H3 (7)] have been explored. Complex 3 exhibited the highest catalytic activity (ex. TOF = 603 000 h–1, 168 s–1) for ROMP of norbornene (NBE) among a series of (imido)vanadium(V)-alkylidenes, and the cis-specific living ROMPs of NBE proceeded with remarkable activities (TOF = 125 000–157 000 h–1 at 25 °C) by the fluorinated alkoxo analogues (6, 7). The activities by 6, 7 increased at high temperature (50 and 80 °C) and/or upon addition of PMe3 without decrease in the cis selectivity (98%). The ROMPs in the presence of 1-hexene by 3, 7 proceeded without significant decrease in the activities, and the Mn values could be controlled by degree of chain transfer (cross metathesis). These dichlorophenylimido analogues (3, 7) were effective for ROMPs of various norbornene deri...

58 citations


Journal ArticleDOI
TL;DR: In this article, a ring-opening metathesis polymerization was used to obtain high molecular weight renewable homopolymers and block copolymers derived from natural rosin, which exhibit structure-dependent glass transition temperatures, excellent thermal stabilities, and thermoplastic properties.
Abstract: Utilization of biomass for commodity polymers has gained tremendous interest. We report a method to prepare high molecular weight renewable homopolymers and block copolymers derived from natural rosin. Monomers with high renewable content (70 wt %) were prepared via a simple esterification reaction between dehydroabietic alcohol and 5-exo-norbornenecarboxylic acid. Living and controlled polymerization of these monomers were achieved by ring-opening metathesis polymerization to obtain polymers with molecular weight up to ∼500 kg/mol. These homopolymers exhibit structure-dependent glass transition temperatures, excellent thermal stabilities, and thermoplastic properties. Chain entanglement molecular weight was determined via rheological assessments for such polymers with bulky side moieties. Using the living ROMP, dehydroabietic-based homopolymer was chain-extended with a soybean oil-derived norbornene monomer to yield triblock copolymers, which showed behaviors of thermoplastic elastomers.

55 citations


Journal ArticleDOI
TL;DR: In this paper, a series of α-diimine ligands and their corresponding palladium complexes were synthesized and characterized, which could lead to metal complexes with very similar electronic and steric environments around a palladium center.

Journal ArticleDOI
TL;DR: In this article, the first mesoporous films modified with two different photochromic homopolymers by surface-initiated ring opening metathesis polymerization (SI-ROMP) are presented.
Abstract: The control of ionic permselectivity in porous films is an interesting aspect in the context of lab-on-chip devices and μ-electronics. Especially, visible light triggered ionic permselectivity control is of relevance because control by light can be maintained externally without changing internal system parameters. In addition, light is a sustainable energy source if sunlight is used. Here, we present the first mesoporous films modified with two different photochromic homopolymers by surface-initiated ring opening metathesis polymerization (SI-ROMP). Spiropyran- and spirooxazine functionalized norbornene monomers and the corresponding ROMP homopolymers are synthesized in solution and in mesopores and compared concerning their optical properties such as photochromic conversion kinetics, photostability, and the ratio of converted molecules. Optical properties are investigated using UV/VIS spectroscopy and 1H-NMR spectroscopy. Especially, spirooxazine, whose surface functionalization has not been studied in detail, shows fast switching properties and higher ratios of photochromically interconverted molecules. After grafting spiropyran- and spirooxazine norbornene homopolymers into mesopores, a slightly faster photochromic interconversion of polymers located inside the mesopores is observed compared to the solution polymers.

Journal ArticleDOI
TL;DR: Efficient tandem ortho-C-H-amination/ipso-cyanation of iodoarenes was accomplished under a norbornene-mediated Pd-catalyzed process and a series of functionalized 2-aminobenzonitriles with much potential in the pharmaceutical industry were obtained.

Journal ArticleDOI
TL;DR: A palladium-catalyzed arylboration of norbornene or norbornadiene with aryL halides and bis(pinacolato)diboron has been disclosed and is complementary to the existing methods and well tolerable with a variety of functional groups.
Abstract: A palladium-catalyzed arylboration of norbornene or norbornadiene with aryl halides and bis(pinacolato)diboron has been disclosed. Mechanistic studies suggest that the reaction proceeds under a Catellani-type coupling to render versatile multifunctionalized alkylboranes in good yields. This reaction is complementary to the existing methods and is well tolerable with a variety of functional groups and readily scaled-up to a gram scale without deteriorating the yield.

Journal ArticleDOI
TL;DR: The controlled ring-opening polymerization of the β-thiolactone derived from N- Boc cysteine was achieved using N-Boc-L-cysteine methyl ester as the initiator in NMP at room temperature, demonstrating the utility of the thiol group at the propagating terminal.

Journal ArticleDOI
TL;DR: The novel pyridazine derivatives (8, 9) efficiently inhibited the cytosolic human carbonic anhydrase isoenzymes I and II and were evaluated for their in vitro acetylcholinesterase inhibitory activity.

Journal ArticleDOI
TL;DR: In this article, the ferrocene-chelating heteroscorpionate complex (FCP,B)PdMe, fc = 1,1′-ferrocenediyl, pz = pyrazole, catalyzes the addition polymerization of norbornene derivatives upon oxidation with [AcFc][BArF] {acetyl ferrocenium tetrakis(3,5-bis(trifluoromethyl)phenyl)borate}.
Abstract: The ferrocene-chelating heteroscorpionate complex [(fc(PPh2){BH{(3,5-Me)2pz}2})PdMe] {(fcP,B)PdMe, fc = 1,1′-ferrocenediyl, pz = pyrazole} catalyzes the addition polymerization of norbornene and norbornene derivatives upon oxidation with [AcFc][BArF] {acetyl ferrocenium tetrakis(3,5-bis(trifluoromethyl)phenyl)borate}. In situ reduction of [(fcP,B)PdMe][BArF] in the presence of a substituted norbornene results in significant decrease of catalytic activity. Addition of one equivalent of oxidant restores the activity.

Journal ArticleDOI
TL;DR: In this paper, a linear relationship between the Tg values and the NBE or TCD contents was observed in all cases; the relationship was not affected by α-olefin (number of methylene units in the side chain) employed.
Abstract: Highly efficient synthesis of cyclic olefin (CO) copolymers with high glass transition temperatures (Tg) as well as high catalytic activity have been attained not only by copolymerization of norbornene (NBE) with α-olefins (1-hexene, 1-octene, 1-dodecene), but also by copolymerization of tetracyclododecene (TCD) with α-olefins using half-titanocene catalysts, Cp′TiCl2(N═CtBu2) [Cp′ = tBuC5H4 (1), Cp (2)] in the presence of MAO. Linear relationships between the Tg values and the NBE or TCD contents were observed in all cases; Tg values in poly(TCD-co-α-olefin)s were higher than those in poly(NBE-co-α-olefin)s with the same CO contents. NBE and TCD incorporations in these copolymerization under high NBE or TCD feed conditions (especially by 2) were not affected by α-olefin (number of methylene units in the side chain) employed. An introduction of terminal olefinic double bond into the polymer side chain could be attained, if the copolymerization of NBE with 1-octene by 1 was conducted in the presence of 1,7...

Journal ArticleDOI
TL;DR: A catalytically asymmetric palladium/norbornene-catalyzed reaction is reported, where α-aryl tetrahydroquinoline derived phosphoramidite L15 is found to be the optimum ligand.

Journal ArticleDOI
TL;DR: These findings establish protein bioconjugation with functionalized polynorbornenes as an effective alternative to conventional protein/polymer modification strategies and further expand the toolbox for protein biconjugates.

Journal ArticleDOI
TL;DR: In this paper, the synthesis of cyclic olefin copolymers (COCs) using group 4 transition metal (titanium and zirconium) complex catalysts has been reviewed.
Abstract: Selected results for the synthesis of cyclic olefin copolymers (COCs)—especially copolymerizations of norbornene (NBE) or tetracyclododecene (TCD) with ethylene and α-olefins (1-hexene, 1-octene, 1-dodecene)—using group 4 transition metal (titanium and zirconium) complex catalysts have been reviewed. Half-titanocenes containing an anionic ancillary donor ligand, Cp’TiX2(Y) (Cp’ = cyclopentadienyl; X = halogen, alkyl; Y = anionic donor ligand such as aryloxo, ketimide, imidazolin-2-iminato, etc.), are effective catalysts for efficient synthesis of new COCs; ligand modifications play an important role for the desired copolymerization. These new COCs possess promising properties (high transparency, thermal resistance (high glass transition temperature), low water absorption, etc.), thus it is demonstrated that the design of an efficient catalyst plays an essential role for the synthesis of new fine polyolefins with specified properties.

Journal ArticleDOI
TL;DR: A palladium/norbornene-catalyzed ortho-C–H alkylation and ipso-alkynylation reaction for the synthesis of 2-alkyl-1-alkYNyl arenes was reported, and good to excellent yields were achieved.
Abstract: A palladium/norbornene-catalyzed ortho-C–H alkylation and ipso-alkynylation reaction for the synthesis of 2-alkyl-1-alkynyl arenes was reported. By the use of 1,1-dimethyl-2-alkynols as alkynyl reagents, the side O-alkylation reaction was mostly inhibited, and the reactivity of the three components matched well. As a result, A- and B-type side-products could be substantially inhibited and good to excellent yields were achieved.

Journal ArticleDOI
TL;DR: B3LYP/6-31++G(d) calculations indicated that the reaction of (2E)-3-phenyl- 2-nitroprop-2-enenitrile with cyclopentadiene catalyzed by cations of 1,3-dialkylimidazolium ionic liquid shall not take place according to the classical scheme of one-step [2+4] Diels–Alder cycloaddition.
Abstract: B3LYP/6-31++G(d) calculations indicated that the reaction of (2E)-3-phenyl-2-nitroprop-2-enenitrile with cyclopentadiene catalyzed by cations of 1,3-dialkylimidazolium ionic liquid shall not take place according to the classical scheme of one-step [2+4] Diels–Alder cycloaddition. Along the path finally leading to bicyclo[2.2.1]hept-5-ene (norbornene) with a nitro group in endo orientation, the process of bicarbocyclic skeleton formation shall take place according to the domino mechanism, via [2+4] heterocycloadduct. On the other hand, along the path leading finally to bicyclo[2.2.1]hept-5-ene with a nitro group in exo orientation, acyclic adduct with a zwitterionic nature is formed in the first reaction, which undergoes cyclisation next in the second step of the reaction.

Journal ArticleDOI
TL;DR: Surprisingly, ring-opening metathesis, late-stage diallylation, followed by ring-closing met athesis delivers triquinane as well as propellane derivatives.

Journal ArticleDOI
TL;DR: It is proposed the chemistry is best rationalized as a formal insertion of Pt(0) into a Zr-C or Ti-Cl bond.
Abstract: Reaction of transition metal “frustrated” Lewis pair compounds of the type [Cp2Zr(Me)(OC(CF3)2CH2PtBu2)] with the low valent platinum species [Pt(norbornene)3] leads to the unexpected formation of a heterobimetallic species [Cp2Zr{Pt(Me)}(OC(CF3)2CH2PtBu2)]. Single crystal X-ray analysis reveals an unusual T-shaped geometry at the platinum center, with a relevant C–Pt–P angle of 163.3(3)°. Treatment of this compound with PMe3 yields [Pt(PMe3)4] and regenerates the zirconium precursor. Treatment with [(Et2O)2H][B(C6F5)4] protonates off the methyl ligand to give an ether adduct at platinum. Analogous observations are made with titanium–platinum species. We propose the chemistry is best rationalized as a formal insertion of Pt(0) into a Zr–C or Ti–Cl bond.

Journal ArticleDOI
TL;DR: In this paper, the synthesis, characterization, and ring-opening metathesis polymerization (ROMP) of a novel norbornene-based boron difluoride (BF2) formazante monomer are described in detail.
Abstract: The synthesis, characterization, and ring-opening metathesis polymerization (ROMP) of a novel norbornene-based boron difluoride (BF2) formazante monomer are described in detail. The polymerization studies confirmed ROMP to occur in the presence of BF2 formazanates, and also demonstrated the controlled nature of the polymerization. The polymers retained many of the unique characteristics of the monomers in dichloromethane, including absorption and emission at maximum wavelengths of 518 and 645 nm, large Stoke's shifts (υST = 127 nm, 3800 cm−1), and the ability to act as electron reservoirs to form borataverdazyl-based poly(radical anions) (). Furthermore, the results described in this paper demonstrate the potential of these and related polymers based on BF2 formazanates as redox-active, light-harvesting materials.

Journal ArticleDOI
TL;DR: In this article, the role of (ONSO)CrCl complex on the cis/trans selectivity of resulting polyester as well as enhancement of the reaction rate has been revealed.
Abstract: A (ONSO)CrCl complex-based binary catalyst for efficient ring-opening copolymerization (ROCOP) of epoxide and norbornene anhydride (NA) in a stereoselective manner to afford polymers with variable stereoisomerism is reported. The role of (ONSO)CrCl complex on the cis/trans selectivity of resulting polyester as well as enhancement of the reaction rate has been revealed. The formation of chelates between the endo-diester unit of the polyester chain and the metal center plays a determinate role in the stereoselectivity of the cis-(endo, endo)-polyester in solution copolymerization of endo-NA with epoxides in the presence of metal complex. Additionally, the stereostructure of resulting polyester is also dependent on the polymerization method, NA type, and the bulkiness of the substituent of the formed ester units in the polyester chain. Accordingly, a proposed mechanistic pathway for the stereostructure formation of polyesters is provided.

Journal ArticleDOI
TL;DR: In this article, the [Co(2-hydroxy-1-naphthaldehyde)2(DMF)2] complex was prepared and characterized by X-ray crystallography, successfully supported on modified Fe3O4 nanoparticles using tetraethylorthosilicate (TEOS) and (3-aminopropyl)trimethoxysilane (APTMS).
Abstract: The [Co(2-hydroxy-1-naphthaldehyde)2(DMF)2] complex 1 was prepared and characterized by X-ray crystallography, successfully supported on modified Fe3O4 nanoparticles using tetraethylorthosilicate (TEOS) and (3-aminopropyl)trimethoxysilane (APTMS) and designated as Fe3O4@SiO2@APTMS@complex nanocatalyst. FT-IR, elemental analysis, XRD, VSM and TEM studies have been used to characterize the nanocatalyst. The catalytic activity of Fe3O4@SiO2@APTMS@complex was evaluated by the epoxidation of norbornene, cyclooctene, styrene, α-methyl styrene, trans-stilbene and limonene, with 50–100% conversions and 83–100% selectivities. Furthermore, it was found that Fe3O4@SiO2@APTMS@complex successfully catalyzes the oxidation of activated secondary alkanes such as fluorene, adamantane, diphenyl methane, and ethylbenzene with 40–100% conversions and 80–100% selectivities toward the corresponding products. Based on the obtained results, the heterogeneity and reusability of the catalyst seems promising.

Journal ArticleDOI
TL;DR: A detailed experimental/theoretical study of the migratory insertion of norbornene into gold(III)−carbon bonds of discrete (P,C)-cyclometalated gold (III) alkyl complexes is reported in this paper.

Journal ArticleDOI
TL;DR: In this paper, the synthesis of ruthenium metathesis catalysts containing unsymmetrical N-trifluoromethyl NHC ligands was reported.