Showing papers on "Norbornadiene published in 2004"
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01 Jan 2004
TL;DR: Kaupp and Kropp as mentioned in this paper proposed a 2+2-cyclobutane synthesis (2+2)-cycle synthesis (Liquid Phase): Introduction and Mechanistic Consideration, G.G.
Abstract: Photochemistry Cis-Trans Isomerization of Alkenes, J. Saltiel, D.F. Sears, Jr., D.-H. Ko, and K.-M. Park Photorearrangement and Fragmentation of Alkenes, P.J. Kropp (2+2)-Cyclobutane Synthesis (Liquid Phase): Introduction and Mechanistic Consideration, G. Kaupp Cyclobutane Synthesis in the Solid Phase: Introduction and Mechanistic Considerations, G. Kaupp Photochemical Synthesis of Cage Compounds: Propellaprismanes and their Precursors, R. Gleiter and B. Treptow Copper(I) Catalyzed Intra- and Intermolecular Photocycloaddition Reactions of Alkenes, K. Langer and J. Mattay Photoreactions of Alkenes in Protic Media, P.J. Kropp The p-Cyclopropene Rearrangements, H.E. Zimmerman Diene/Cyclobutene Photochemistry, W.J. Leigh Photochemistry of Acyclic 1,3,5-Trienes and Related Compounds, W.H. Laarhoven and H.J.C. Jacobs Photochemistry of Vitamin D and Related Compounds, H.J.C. Jacobs and W.H. Laarhoven Photochemistry of Polyenes Related to Vitamin A, R.S.H. Liu Fulgides and Related Systems, H.G. Heller The Di-p-Methane Rearrangement, H.E. Zimmerman Photorearrangements of Benzobarrelenes and Related Analogues, C.-C. Liao and P.-H. Yang The Photochemistry of Dibenzobarrelene (9,10-Ethenoanthracene) and its Derivatives, J.R. Scheffer and J. Yang Valence Isomerization Between Norbornadiene and Quadricyclane Derivatives-A Solar Energy Storage Process, K. Maruyama and Y. Kubo Ring Isomerization of Benzene and Naphthalene Derivatives, A. Gilbert Phototransposition and Photo-Ring Contraction Reactions of 4-Pyrones and 4-Hydroxypyrylium Cations, J.W. Pavlik Photochemical Aromatic Substitution, J. Cornelisse Photochemical Reactions of Arenes with Amines, N.J. Bunce Intra- and Intermolecular Cycloadditions of Benzene Derivatives, P.A. Wender and T.M. Dore Cyclization of Stilbene and its Derivatives, A. Gilbert Ene Reactions with Singlet Oxygen, A.G. Griesbeck Photooxygenation of 1,3-Dienes, W. Adam and A.G. Griesbeck Photorearrangement of Endope roxides, J. Rigaudy Photochemical Methods for the Synthesis of 1,2-Dioxetanes, A.L. Baumstark and A. Rodriguez Oxidation of Aromatics, A. Albinia and M. Freccero Cyclobutane Photochemistry, K. Mizuno and C. Pac Photochemistry of Oxiranes - Photoreactions of Epoxynaphthoquinones, K. Maruyama and Y. Kubo Photodecarboxylation of Acids and Lactones, P. Wan and D. Budac The Photochemistry of Esters of Carboxylic Acids, J.A. Pincock Carbene Formation in the Photochemistry of Cyclic Ketones, S.M. Roberts Norrish Type I Processes of Ketones: Basic Concepts, C. Bohne Norrish Type I Processes of Ketones: Selected Examples and Synthetic Applications, C. Bohne Photoinduced Intermolecular Hydrogen Abstraction Reactions of Ketones, M. Rubin Hydrogen Abstraction Reactions of a-Diketones, M. Rubin Norrish Type II Photoelimination of Ketones: Cleavage of 1,4-Biradicals Formed by y-Hydrogen Abstraction, .J.-P. Wagner Norrish
596 citations
TL;DR: A rhodium-catalyzed asymmetric 1,4-addition of arylboronic acids to fumaric and maleic compounds has been developed and chiral norbornadiene ligands have proved to be uniquely effective to achieve high enantioselectivity.
149 citations
TL;DR: The photoluminescence quantum yield of the W-based poly(t-Bu2CzPA) was 55%, while that of the Rh-based one was as low as 3.6%.
Abstract: Novel carbazole-containing polymers, i.e., poly(3,6-di-tert-butyl-N-(p-ethynylphenyl)carbazole) [poly(t-Bu2CzPA)] and poly(N-(p-ethynylbenzoyl)carbazole) [poly(CzCOPA)] were synthesized by the polymerization of the corresponding carbazole-containing acetylene monomers using [(norbornadiene)RhCl]2−Et3N, WCl6−n-Bu4Sn, and WCl4 catalysts. The UV−vis absorption band edge wavelengths of the polymers obtained by the polymerization with W catalysts were longer than those of the Rh-based polymers. The photoluminescence quantum yield of the W-based poly(t-Bu2CzPA) was 55%, while that of the Rh-based one was as low as 3.6%. The photocurrent of poly(t-Bu2CzPA) was 40−50 times higher than the dark current. Poly(t-Bu2CzPA) in conjunction with iridium complexes exhibited electroluminescence (13−18 cd/m2).
97 citations
TL;DR: A practical synthesis of enantiomerically pure DIANANE is described, starting from norbornadiene in four steps: Pd-MOP catalyzed Hayashi-hydrosilylation/Tamao-Fleming oxidation, oxidation to norbornane-2,5-dione, endo-selective reductive amination with benzylamine, and hydrogenolytic debenzylation.
Abstract: DIANANE (endo,endo-2,5-diaminonorbornane) is a novel chiral C2-symmetric diamine, based on the rigid bicyclo[2.2.1]heptane scaffold. Schiff-base ligands derived from DIANANE have already found use in asymmetric catalysis, e.g., in the highly enantioselective Nozaki−Hiyama−Kishi reaction. We herein describe a practical synthesis of enantiomerically pure DIANANE, starting from norbornadiene in four steps: (i) Pd-MOP catalyzed Hayashi-hydrosilylation/Tamao−Fleming oxidation, (ii) oxidation to norbornane-2,5-dione, (iii) endo-selective reductive amination with benzylamine, and (iv) hydrogenolytic debenzylation. None of the steps involves chromatographic purification. For the Tamao−Fleming oxidation, the use of hydrogen peroxide in the form of its urea clathrate instead of aqueous solution proved beneficial. By the above sequence, enantiomerically pure (ee ≥99%) DIANANE was obtained from norbornadiene in 40−50% overall yield. The relative and absolute configuration of DIANANE was confirmed by X-ray crystallog...
64 citations
TL;DR: All the new compounds (apart from the CO and MeCN adducts) have been characterised by X-ray crystallography and can be considered as being "operationally unsaturated", effectively acting as a source of 16-electron.
Abstract: Chromium and ruthenium complexes of the chelating phosphine borane H3B·dppm are reported. Addition of H3B·dppm to [Cr(CO)4(nbd)]
(nbd = norbornadiene) affords [Cr(CO)4(η1-H3B·dppm)] in which the borane is linked to the metal through a single B–H–Cr interaction. Addition of H3B·dppm to [CpRu(PR3)(NCMe)2]+
(Cp =
η5-C5H5) results in [CpRu(PR3)(η1-H3B·dppm)][PF6]
(R = Me, OMe) which also show a single B–H–Ru interaction. Reaction with [CpRu(NCMe)3]+ only resulted in a mixture of products. In contrast, with [Cp*Ru(NCMe)3]+
(Cp*
=
η5-C5Me5) a single product is isolated in high yield: [Cp*Ru(η2-H3B·dppm)][PF6]. This complex shows two B–H–Ru interactions. Reaction with L = PMe3 or CO breaks one of these and the complexes [Cp*Ru(L)(η1-H3B·dppm)][PF6] are formed in good yield. With L = MeCN an equilibrium is established between [Cp*Ru(η2-H3B·dppm)][PF6] and the acetonitrile adduct. [Cp*Ru(η2-H3B·dppm)][PF6] can be considered as being “operationally unsaturated”, effectively acting as a source of 16-electron [Cp*Ru(η1-H3B·dppm)][PF6]. All the new compounds (apart from the CO and MeCN adducts) have been characterised by X-ray crystallography. The solid-state structure of H3B·dppm is also reported.
62 citations
TL;DR: Ru-catalyzed [2 + 2] cycloadditions between norbornadiene and alkynyl halides were found to occur in moderate to good yields and can be transformed into a variety of products that are difficult or impossible to obtain via directcycloaddition.
55 citations
TL;DR: In this article, a stereoregular polymerization of poly(n-n-octyl-3-carbazoyl)acetylene (PNOCzA) was successfully performed with a [Rh(NBD)Cl]2 (NBD = norbornadiene) catalyst to afford poly(N-n, octyl, 3-carbazoyal)acetyl) as a new type of possible electron-transporting polymer in fairly high yields when triethylamine, chloroform, or dimethylformamide was used as
Abstract: Stereoregular polymerization of (N-n-octyl-3-carbazoyl)acetylene was successfully performed with a [Rh(NBD)Cl]2 (NBD = norbornadiene) catalyst to afford poly(N-n-octyl-3-carbazoyl)acetylene (PNOCzA) as a new type of possible electron-transporting polymer in fairly high yields when triethylamine, chloroform, or dimethylformamide was used as the polymerization solvent. The resulting polymers were composed of amorphous cis−transoid isomers bearing a yellow color or crystalline cis−transoid isomers having an orange color, called a columnar, as a π-conjugated molecular assembly at the solid state. The cis-to-trans isomorization of the yellow and orange polymers was induced by compression at 200 kg/cm2 under vacuum at room temperature for 10 min. The polymers obtained before and after compression were characterized in detail using 1H NMR, wide-angle X-ray diffraction, laser Raman, electron spin resonance, and diffuse reflective UV−vis (DRUV−vis) methods. The data showed that compression of the orange polymers r...
54 citations
TL;DR: Copper-catalyzed Michael addition of a Grignard reagent followed by removal of the TMS group with TBAF were the most reliable methods to transform (+)-18 into valuable starting materials 20a-e for the enantioselective synthesis of cyclopentenoid systems.
Abstract: Here we describe the synthesis and use of the Pulegone-derived bidentate P,S ligands PuPHOS and CyPuPHOS in the intermolecular Pauson−Khand reaction. Ligand exchange reaction of hexacarbonyldicobalt−alkyne complexes with PuPHOS provides a diasteromeric mixture of complexes (up to 4.5:1) from which the major isomers can be conveniently separated by simple crystallization. An isomerization−crystallization sequence of the original mixture results in a dynamic resolution that allows the preparation of the pure major Co2(μ-TMSC2H)(CO)4−PuPHOS (15a) in a multigram scale. Pauson−Khand reaction of 15a with norbornadiene provided, for the first time, the corresponding enone 18 with up to 93% yield and 97% ee. The use of (+)-18 as a surrogate of chiral cyclopentadienone is also demonstrated. Copper-catalyzed Michael addition of a Grignard reagent followed by removal of the TMS group with TBAF were the most reliable methods to transform (+)-18 into valuable starting materials 20a−e for the enantioselective synthesis...
52 citations
TL;DR: X-ray crystallography, along with solution NMR structural analysis of the pi-allyl intermediate and competition experiments, conclusively established the reaction proceeded via a retention-retention pathway, which contrasts with that defined for Pd-catalyzed allylic alkylations, which proceed via an inversion-inversion pathway.
Abstract: Enantiomerically enriched, deuterated branched carbonates (Z)-(S)-PhCH(O2COMe)−CHCHD (1a), (Z)-(R)-PhCH(O2COMe)CHCHD (2a), and linear carbonate (E)-(S)-PhCHCHCHD(O2COMe) (12) were employed as probes in the Mo-catalyzed asymmetric allylic alkylation with sodium dimethyl malonate, catalyzed by ligand complex 10 derived from the mixed benzamide/picolinamide of (S,S)-trans-diaminocyclohexane and (norbornadiene)Mo(CO)4. X-ray crystallography, along with solution NMR structural analysis of the π-allyl intermediate and competition experiments, conclusively established the reaction proceeded via a retention−retention pathway. This mechanism contrasts with that defined for Pd-catalyzed allylic alkylations, which proceed via an inversion−inversion pathway.
51 citations
TL;DR: Complex OsHCl(CO)(P i Pr 3 ) 2 catalyzes the ring-opening metathesis polymerization (ROMP) of norbornene and 2,5-norbornadiene to give poly(norbornene) and poly(nakedadiene), respectively In both cases the resulting polymers have a high cis (74-95%) content as discussed by the authors.
50 citations
TL;DR: The octahedral cluster complex (iPr3P)6Rh6H12][Y]2 has been characterized by NMR, mass spectroscopy, and X-ray crystallography as discussed by the authors.
Abstract: Treatment of [(iPr3P)2Rh(nbd)][Y] {nbd = norbornadiene, Y = B{3,5-(CF3)2C6H3}4- [B(ArF)4] or 1-H-closo-CB11Me11-} with H2 (ca. 4 atm) results in the isolation, in moderate yield, of the octahedral cluster complex [(iPr3P)6Rh6H12][Y]2 1. The cluster (for both anions) has been characterized by NMR, mass spectroscopy, and X-ray crystallography. These show 1 to have 12 edge-bridging hydrogen atoms, and the structure bears more resemblance to clusters of the early transition metals with pi-donor ligands than those of the late transition metals with pi-acceptor ligands. Intermediate complexes on the route to 1, namely, the nonclassical dihydrogen complexes [(iPr3P)2Rh(H)2(eta2-H2)x][B(ArF)4] (x = 1 or 2), have been observed spectroscopically. The high hydride content of 1 makes it a possible model for nanocluster colloidal Rh(0) catalysts that are used in olefin and arene hydrogenation.
TL;DR: In this paper, the role of chiral amine cocatalyst in the recently discovered helix-sense-selective polymerization of a phenylacetylene using a catalytic system consisting of an achiral rhodium complex ([Rh(norbornadiene)Cl] 2 ) as the catalyst and a chiral amino acid as the cocat catalyst was examined.
TL;DR: In this article, the reaction between RuCl 2 (PPh 3 ) 3 ] and piperidine (pip) gives the novel [RuCl 2 PPh 3 ] complex, which quantitatively polymerizes norbornene (NBE) via ring opening metathesis polymerization for less than 1min at RT, in the presence of 5μL of ethydiazoacetate.
Abstract: Reaction between [RuCl 2 (PPh 3 ) 3 ] and piperidine (pip) gives the novel [RuCl 2 (PPh 3 ) 2 (pip)] complex, which quantitatively polymerizes norbornene (NBE) via ring opening metathesis polymerization for less than 1 min at RT, in the presence of 5 μL of ethydiazoacetate. An M w / M n value of 1.05 is obtained if amounts of norbornene are added in several batches up to the [NBE]/[Ru] = 5.000. Norbornadiene is polymerized with 48% yield for 5 min at RT. The precursor complex gives only 63% of polynorbornene and 6% of polynorbornadiene for 5 min at 50 °C. 31 P{ 1 H} NMR analyses indicate that the new complex does not undergo dimerization in solution as it occurs in the case of the precursor complex. It is proposed that the presence of the piperidine is appropriated in enhancing the rate of reaction and controlling the ruthenium metathesis catalysis via a highly active five-coordinated mononuclear Ru(II) complex.
TL;DR: Several optically active (CpR)Co(L) (L = 1,5-cyclooctadiene, norbornadiene) complexes were prepared as discussed by the authors.
TL;DR: This novel procedure constitutes the first asymmetric version with unstrained acyclic alkenes and the high stereoselectivity of the process is due to the easy thermodynamic epimerization at the C5 center in the resulting 5-sulfinyl-2-cyclopentenone adducts.
Abstract: The use of sulfoxides as chiral auxiliaries in asymmetric intermolecular Pauson-Khand reactions is described. After screening a wide variety of substituents on the sulfur atom in alpha,beta-unsaturated sulfoxides, the readily available o-(N,N-dimethylamino)phenyl vinyl sulfoxide (1 i) has proved to be highly reactive with substituted terminal alkynes under N-oxide-promoted conditions (CH3CN, 0 degrees C). In addition, these Pauson-Khand reactions occurred with complete regioselectivity and very high diastereoselectivity (de=86->96 %, (S,R(S)) diastereomer). Experimental studies suggest that the high reactivity exhibited by the vinyl sulfoxide 1 i relies on the ability of the amine group to act as a soft ligand on the alkyne dicobalt complex prior to the generation of the cobaltacycle intermediate. On the other hand, both theoretical and experimental studies show that the high stereoselectivity of the process is due to the easy thermodynamic epimerization at the C5 center in the resulting 5-sulfinyl-2-cyclopentenone adducts. When it is taken into account that the known asymmetric intermolecular Pauson-Khand reactions are limited to the use of highly reactive bicyclic alkenes, mainly norbornene and norbornadiene, this novel procedure constitutes the first asymmetric version with unstrained acyclic alkenes. As a demonstration of the synthetic interest of this sulfoxide-based methodology in the enantioselective preparation of stereochemically complex cyclopentanoids, we have developed very short and efficient syntheses of the antibiotic (-)-pentenomycin I and the (-)-aminocyclopentitol moiety of a hopane triterpenoid.
TL;DR: In this article, a ring opening metathesis polymerisation (ROMP) of norbornene and norbornadiene derivatives containing oxygen is investigated using Grubbs well-defined ruthenium initiator.
TL;DR: In this article, the titanium-catalyzed reaction of norbornadiene and cyclooctadiene with decaborane was used to synthesize poly(6-(norbornenyl)decaborane) and poly(cyclooctenyldecabane) polymers with Mn > 30 kDa and polydispersities between 1.1 and 1.8.
TL;DR: In this article, the reactivity of the N-3-ligand rhodium nbd complex (fac-kappa(3)-Me-dpa)Rh-I(nbd)](+) (1111 toward H+ and the oxidants Ag+, FeCl3, and ferrocenium (Fc(+)) has been investigated.
TL;DR: In this article, N-trimethylsilyl-7-azanorbornadiene (TMSAN) is synthesized and chemisorbed on the silicon(100)-2 × 1 surface under ultra-high vacuum conditions and the resulting structure is determined using scanning tunnelling microscopy (STM).
Abstract: N-trimethylsilyl-7-azanorbornadiene (TMSAN) is synthesized and chemisorbed on the silicon(100)-2 × 1 surface under ultra-high vacuum conditions and the resulting structure is determined using scanning tunnelling microscopy (STM). The binding exhibits poor short-range order, similar to that for norbornadiene. Patterning of the adsorbate is demonstrated following STM electron-stimulated depassivation of a silicon(100)-2 × 1-H surface, indicating that the placement of TMSAN on the surface can be controlled. Density-functional theory (DFT) calculations verify the close analogy between the binding of TMSAN and its much studied parent compound, norbornadiene. This analogue is novel, however, in that it can provide anchor points for construction at the molecular level above the silicon surface. How such construction could proceed is controlled by the topology of the nitrogen atom and the torsional potential for rotation about the N–Si bond. While these key features are not readily apparent from the STM results, DFT predicts that TMSAN above silicon(100) adopts a structure containing an azimuthal rotor: the nitrogen atom is in a planar configuration so that the N–Si bond is normal to the silicon surface, there being also nearly free rotation about the N–Si bond. Further, variants of TMSAN are considered in which a double-well potential for nitrogen inversion is predicted, suggesting that chemical control can be established over the architectural function of this class of compounds.
TL;DR: The reactivity of the metalloligand [Pt 2 (μ-S) 2 (PPh 3 ) 4 ] towards a wide range of platinum(II) and palladium-II chloride complex substrates [L 2 MCl 2 ] has been explored, using the technique of electrospray ionisation mass spectrometry to directly analyse reaction solutions.
TL;DR: Variable temperature (1)H NMR experiments show that the [Ni(diene)] fragments are freely rotating even at 193 K.
Abstract: The nickelacarboranes [NEt(4)][2-(eta(3)-C(3)H(4)R)-closo-2,1,7-NiC(2)B(9)H(11)] (R = H (1a), Ph (1b)) have been synthesized via reaction between [Na](2)[nido-7,9-C(2)B(9)H(11)] and [Ni(2)(micro-Br)(2)(eta(3)-C(3)H(4)R)(2)] in THF (THF = tetrahydrofuran), followed by addition of [NEt(4)]Cl. Protonation of 1a in the presence of a donor ligand L affords the complexes [2,2-L(2)-closo-2,1,7-NiC(2)B(9)H(11)] (L = CO (2), CNBu(t) (3)). Addition of PEt(3) (1 equiv) to 2 produces quantitative conversion to [2-CO-2-PEt(3)-closo-2,1,7-NiC(2)B(9)H(11)], 4. Species 2-4 exhibit in solution hindered rotation of the NiL(2) fragment with respect to the eta(5)-C(2)B(9) cage unit. Protonation of 1a in the presence of a diene affords the neutral complexes [2-(eta(2):eta(2)-diene)-closo-2,1,7-NiC(2)B(9)H(11)] (diene = C(5)Me(5)H (5), dcp (6), cod (7), nbd (8), chd (9), and cot (10a); dcp = dicyclopentadiene, cod = 1,5-cyclooctadiene, nbd = norbornadiene, chd = 1,3-cyclohexadiene, and cot = cyclooctatetraene). Variable temperature (1)H NMR experiments show that the [Ni(diene)] fragments are freely rotating even at 193 K. A small quantity of the di-cage species [2,2'-micro-(1,2:5,6-eta-3,4:7,8-eta-cot)-(closo-2,1,7-NiC(2)B(9)H(11))(2)] (10b) is formed as a coproduct in the synthesis of 10a. This species can be rationally synthesized by protonation of 1a and subsequent addition of 10a.
TL;DR: In this article, the synthesis of cyclic oligomers with pendant norbornadiene (NBD) moieties based on the calixarenes was examined, and it was found that the photochemical valence isomerization of the obtained Calixarene derivatives containing NBD moieties proceeded very smoothly to afford the corresponding quadricyclane (QC) moivities, and the large refractive index changes (An's = 0.028-0.061) before and after photo-isomerization.
Abstract: We have examined the synthesis of cyclic oligomers with pendant norbornadiene (NBD) moieties based on the calixarenes [p-tert-butylcalix[8]arene (BCA), p-methylcalix[6]arene (MCA), )calix[4]resorcinarene (CRA), 2,8,14,20-tetra-decylcalix]4]resorcinarene (CRA 1 0 ), and 2,8,14,20-tetrakis(p-hydroxyphenyl)calix[4]resorcinarene (CRA p h )]. The photochemical valence isomerization of the obtained calixarene derivatives containing NBD moieties proceeded very smoothly to afford the corresponding quadricyclane (QC) moieties, and it was found that the large refractive-index changes (An's = 0.028-0.061) before and after photo-isomerization.
TL;DR: The results of these studies, along with x-ray crystallography and solution NMR structural analysis of the pi-allyl intermediate, conclusively established the reaction proceeded by a retention-retention pathway.
Abstract: Enantiomerically enriched, deuterated branched carbonates (Z)-(S)-PhCH(OCO2Me)-CH = CHD (1-D), (Z)-(R)-PhCH(OCO2Me)CH = CHD (2-D), and linear carbonate (E)-(S)-PhCH = CHCHD(OCO2Me) (3-D) were used as probes in the Mo-catalyzed asymmetric allylic alkylation with sodium dimethyl malonate, catalyzed by ligand-complex 11 derived from the mixed benzamide/picolinamide of (S,S)-transdiaminocyclohexane and (norbornadiene)Mo(CO)4. The results of these studies, along with x-ray crystallography and solution NMR structural analysis of the π-allyl intermediate, conclusively established the reaction proceeded by a retention–retention pathway. This mechanism contrasts with that defined for Pd-catalyzed allylic alkylations, which proceed by an inversion–inversion pathway. A proposed rationale for the retention pathway for nucleophilic substitution involves CO-coordination to form a tri-CO intermediate, followed by complexation with the anion of dimethyl malonate to produce a seven-coordinate intermediate, which reductively eliminates to afford product with retention of configuration.
TL;DR: In this article, the structure of the adduct 2a was re-investigated and determined by X-ray structural analysis, and the rhodiadithiolene complexes and those adducts showed the catalytic activities for the thermal isomerization from Q to norbornadiene (NBD).
TL;DR: The homo-Diels-Alder (HDA) reaction of norbornadiene and internal functionalized alkynes leading to 8,9 disubstituted deltacyclenes using readily available electron-rich phosphine-ruthenium(II) catalysts is described in this paper.
TL;DR: A family of terminal alkyne dicobalthexacarbonyl complexes bearing groups with a range of electron-withdrawing abilities has been synthesized as mentioned in this paper.
TL;DR: In this article, the presence of alkyne in the reaction mixture leads to an increase in cycloolefin conversion and to the formation of blocky polymers with high molecular weights and better solubility in CHCl 3 than polynorbornene and polynornadiene homopolymers.
Abstract: Metathesis polymerization of norbornene and norbornadiene in the presence of tert -butylacetylene initiated by seven-coordinate bimetallic tungsten–tin and molybdenum–tin compounds of the [MCl(SnCl 3 )(CO) 3 (NCMe) 2 ] (M = Mo, W) type was investigated. The presence of alkyne in the reaction mixture leads to an increase in cycloolefin conversion and to the formation of blocky polymers with high molecular weights and better solubility in CHCl 3 than polynorbornene and polynorbornadiene homopolymers. The structure of polymers was determined by 1 H and 13 C{ 1 H} NMR spectroscopy. In addition to polymers small amounts of cooligomers and cyclotrimers were also detected in the above reactions. The reactivity of tungsten(II) and molybdenum(II) complexes towards tert -butylacetylene is higher than towards olefins. Monitoring of reactions of [WCl(SnCl 3 )(CO) 3 (NCEt) 2 ] with norbornadiene and tert -butylacetylene by 1 H NMR spectroscopy made it possible to observe the coordination of alkyne to the metal atom in the step preceding polymerization and copolymerization. In those reactions the alkyne plays the role of an activator.
TL;DR: Methylene-bridged ansa-metallocene complexes bearing substituents on the cyclopentadienyl (Cp) and fluorenyl (Flu) moieties have been prepared from (2,7-di-tert-butyl)-9-prop-2-ynyl-9H-fluorene (2), which includes the use of 3-bromo-1propyne which affords the methylene bridging unit by way of an intermolecular Pauson-Khand reaction in which norborn
TL;DR: In this article, a stereospecific polymerization of a novel aromatic acetylene containing an alkyl sulfide group was successfully performed to selectively give the corresponding polymerbearing a cis-transoid structure as a main geometrical form and a very high molecular weight, M n = 1.7-5.8 ×10 6 in high yields.
Abstract: A stereospecific polymerization of a novel aromatic acetylene containing an alkyl sulfide group, i.e., (p-methylthiophenyl)acetylene (pMeSPA) was successfully performed to selectively give the corresponding polymerbearing a cis-transoid structure as a main geometrical form and a very high molecular weight, M n =1.7-5.8 ×10 6 in high yields. This was accomplished when a Rh complex catalyst, [Rh(norbornadiene)Cl] 2 was used in the presence of triethylamine (TEA) solvent as a cocatalyst and its mixed solvents with TEA, together with a detailed characterization of the resulting polymers before and after compression at room temperature. Based on the data obtained before and after compression, it was concluded that compression of the PpMeSPA polymers induced a cis-to-trans isomerization at room temperature under vacuum even in the solid state (the Figure shows the radical generated by compression).
TL;DR: In this article, a bidentate N, 2 1 N 2 2 -1,2-diphenyletheno-bridged porphyrin ligand, Pd I I (Me)(Cl)(N 2 1,N 2 2 −(PhC=CPh)(TPP))(CO)]ClO 4.