Topic
Norbornadiene
About: Norbornadiene is a research topic. Over the lifetime, 2389 publications have been published within this topic receiving 38603 citations.
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TL;DR: In this paper, a polymer containing pendant norbornadiene (NBD) moieties, P(MMA0.43-co-GMA 0.57-PNCA), and measured absorbance and refractive index spectra before and after photoisomerization of NBD moieties.
Abstract: We prepared a polymer containing pendant norbornadiene (NBD) moieties, P(MMA0.43-co-GMA0.57-PNCA), and measured absorbance and refractive index spectra before and after photoisomerization of norbornadiene moieties. Large photoinduced refractive index changes of ∼0.01 were obtained at 632.8 nm, the region far from the absorption band. A quantum yield of 0.50 was obtained for the photoisomerization of NBD moieties in this polymer. These values are sufficient to make efficient channel waveguides by photoisomerization.
45 citations
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TL;DR: The polymerization of several 7-isopropylidene-2,3-disubstituted norbornadienes with a single tungsten oxo alkylidene catalyst, W(O)(CH-t-Bu)(OHMT)(Me2Pyr) to give cis, stereoregular polymers.
Abstract: We report here the polymerization of several 7-isopropylidene-2,3-disubstituted norbornadienes, 7-oxa-2,3-dicarboalkoxynorbornadienes, and 11-oxa-benzonorbornadienes with a single tungsten oxo alkylidene catalyst, W(O)(CH-t-Bu)(OHMT)(Me2Pyr) (OHMT = 2,6-dimesitylphenoxide; Me2Pyr = 2,5-dimethylpyrrolide) to give cis, stereoregular polymers. The tacticities of the menthyl ester derivatives of two polymers were determined for two types. For poly(7-isopropylidene-2,3-dicarbomenthoxynorbornadiene) the structure was shown to be cis,isotactic, while for poly(7-oxa-2,3-dicarbomenthoxynorbornadiene) the structure was shown to be cis,syndiotactic. A bis-trifluoromethyl-7-isopropylidene norbornadiene was not polymerized stereoregularly with W(O)(CHCMe2Ph)(Me2Pyr)(OHMT) alone, but a cis, stereoregular polymer was formed in the presence of 1 equiv of B(C6F5)3.
45 citations
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TL;DR: A cobalt-substrate complex was crystallographically characterized as the opposite diastereomer to that expected for productive hydrogenation demonstrating a Curtin-Hammett kinetic regime similar to rhodium catalysis.
Abstract: Chloride abstraction from [(R,R)-(iPr DuPhos)Co(μ-Cl)]2 with NaBArF 4 (BArF 4 =B[(3,5-(CF3 )2 )C6 H3 ]4 ) in the presence of dienes, such as 1,5-cyclooctadiene (COD) or norbornadiene (NBD), yielded long sought-after cationic bis(phosphine) cobalt complexes, [(R,R)-(iPr DuPhos)Co(η2 ,η2 -diene)][BArF 4 ]. The COD complex proved substitutionally labile undergoing diene substitution with tetrahydrofuran, NBD, or arenes. The resulting 18-electron, cationic cobalt(I) arene complexes, as well as the [(R,R)-(iPr DuPhos)Co(diene)][BArF 4 ] derivatives, proved to be highly active and enantioselective precatalysts for asymmetric alkene hydrogenation. A cobalt-substrate complex, [(R,R)-(iPr DuPhos)Co(MAA)][BArF 4 ] (MAA=methyl 2-acetamidoacrylate) was crystallographically characterized as the opposite diastereomer to that expected for productive hydrogenation demonstrating a Curtin-Hammett kinetic regime similar to rhodium catalysis.
45 citations
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TL;DR: It is shown that the calculated frontier molecular orbitals of Ar(iPr(4))GaGaAr(i Pr(4) are of π-π symmetry, allowing this molecule to engage in a wider range of reactions than permitted by the usual ρ-π* FMOs of C-C π bonds or the τ-n(+) F MOs of heavier group 14 alkyne analogues.
Abstract: The heavier group 13 element alkene analogue, digallene AriPr4GaGaAriPr4 (1) [AriPr4 = C6H3-2,6-(C6H3-2,6-iPr2)2], has been shown to react readily in [n + 2] (n = 6, 4, 2 + 2) cycloaddition reactions with norbornadiene and quadricyclane, 1,3,5,7-cyclooctatetraene, 1,3-cyclopentadiene, and 1,3,5-cycloheptatriene to afford the heavier element deltacyclane species AriPr4Ga(C7H8)GaAriPr4 (2), pseudoinverse sandwiches AriPr4Ga(C8H8)GaAriPr4 (3, 3iso), and polycyclic compounds AriPr4Ga(C5H6)GaAriPr4 (4) and AriPr4Ga(C7H8)GaAriPr4 (5, 5iso), respectively, under ambient conditions. These reactions are facile and may be contrasted with other all-carbon versions, which require transition-metal catalysis or forcing conditions (temperature, pressure), or with the reactions of the corresponding heavier group 14 species AriPr4EEAriPr4 (E = Ge, Sn), which give very different product structures. We discuss several mechanistic possibilities, including radical- and non-radical-mediated cyclization pathways. These mechanism...
45 citations
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TL;DR: The first practical asymmetric version of the intermolecular Pauson-Khand reaction has been developed based on novel chiral (non-racemic) alkoxy acetylene dicobalt hexacarbonyl complexes as discussed by the authors.
44 citations