Scandium-Catalyzed Cyclocopolymerization of 1,5-Hexadiene with Styrene and Ethylene: Efficient Synthesis of Cyclopolyolefins Containing Syndiotactic Styrene–Styrene Sequences and Methylene-1,3-cyclopentane Units

Guo, Fang; Nishiura, Masayoshi; Koshino, Hiroyuki; Hou, Zhaomin

doi:10.1021/ma201271r

Cited by 77 publications

(51 citation statements)

References 63 publications

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“…Similar results have been observed by several workers [188,189,190] for syndiospecific polymerization of styrene using a series of Cp'Ti(OMe) 3 complexes. They explain the high activity by assuming that electron-donating substituents stabilize the active sites [189,190].…”

Section: Role and Type Of Catalystssupporting

confidence: 91%

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The Influence of Ziegler-Natta and Metallocene Catalysts on Polyolefin Structure, Properties, and Processing Ability

et al. 2014

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50 years ago, Karl Ziegler and Giulio Natta were awarded the Nobel Prize for their discovery of the catalytic polymerization of ethylene and propylene using titanium compounds and aluminum-alkyls as co-catalysts. Polyolefins have grown to become one of the biggest of all produced polymers. New metallocene/methylaluminoxane (MAO) catalysts open the possibility to synthesize polymers with highly defined microstructure, tacticity, and steroregularity, as well as long-chain branched, or blocky copolymers with excellent properties. This improvement in polymerization is possible due to the single active sites available on the metallocene catalysts in contrast to their traditional counterparts. Moreover, these catalysts, half titanocenes/MAO, zirconocenes, and other single site catalysts can control various important parameters, such as co-monomer distribution, molecular weight, molecular weight distribution, molecular architecture, stereo-specificity, degree of linearity, and branching of the polymer. However, in most cases research in this area has reduced academia as olefin polymerization has seen significant advancements in the industries. Therefore, this paper aims to further motivate interest in polyolefin research in academia by highlighting promising and open areas for the future.

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Section: Role and Type Of Catalystssupporting

confidence: 91%

“…They explain the high activity by assuming that electron-donating substituents stabilize the active sites [189,190]. However, the tBu 2 Cp analog shows lower catalytic activity in 1-hexene and 1-octene polymerization due to the presence of steric bulk on Cp' [191].…”

Section: Role and Type Of Catalystsmentioning

confidence: 99%

The Influence of Ziegler-Natta and Metallocene Catalysts on Polyolefin Structure, Properties, and Processing Ability

et al. 2014

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“…As reported previously, the s PS ( rrrr > 99%, M n = 127,000, M w / M n = 1.47, [ η ] inh = 0.86) was efficiently obtained by the polymerization of styrene in the presence of scandium catalyst system [(C 5 Me 4 SiMe 3 )Sc(CH 2 C 6 H 4 NMe 2 ‐o ) 2 ]/[Ph 3 C][B(C 6 F 5 ) 4 ] (Table , entry 1) . To obtain amino‐containing functionalized s PS, the polymerization of the amino‐containing styrenic monomers, such as DMAS, DEAS, and DPAS by the half‐sandwich scandium complex [(C 5 Me 4 SiMe 3 )Sc(CH 2 C 6 H 4 NMe 2 ‐o ) 2 ] in combination with [Ph 3 C][B(C 6 F 5 ) 4 ] as cocatalyst was conducted at room temperature in toluene.…”

Section: Introductionmentioning

confidence: 85%

Synthesis of amino‐containing syndiotactic polystyrene as efficient polymer support for palladium nanoparticles

Shi

Guo

et al. 2014

J. Polym. Sci. Part A: Polym. Chem.

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Amino‐containing functionalized syndiotactic polystyrenes with high melting temperatures and temperature stability are synthesized by the direct polymerization of amino‐containing styrenic monomers in the presence of a half‐sandwich scandium catalyst system [(C5Me4SiMe3)Sc(CH2C6H4NMe2‐o)2]/[Ph3C][B(C6F5)4]. The high syndiotactic poly(N,N‐dimethylamino)styrene (rrrr > 99%), then used as novel polymer supports, effectively anchored Pd nanoparticles (3 wt % of Pd) with a diameter of 4 or 5 nm that were uniformly dispersed on polymer matrix.

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“…Coordination of the nitrogen atom of 4 a to the scandium center in cationic species A , generated in situ from the reaction of 2 a ‐Sc with B(C 6 F 5 ) 3 , promotes deprotonation of the ortho ‐C(sp 2 )−H bond of 4 a by the alkyl scandium species to give pyridyl intermediate B ,,. Compound 3 a approaches the scandium site from the 2,6‐diisopropylphenyl group side of intermediate B to avoid unfavorable steric interactions from the coordinated aminobenzyl unit of the counteranion, and insertion of a C=C bond of 3 a into the scandium–pyridyl bond in a 2,1‐fashion diastereoselectively gives intermediate C (favored) or C′ (disfavored) . Subsequent rapid intramolecular 2,1‐insertion of the coordinated C=C bond into the Sc−C bond in C or C′ yields D or D′ , respectively, which upon reaction with 4 a (C−H deprotonation) regenerates B with release of cis ‐ 5 aa (major) or trans ‐ 5 aa (minor), respectively.…”

Section: Methodsmentioning

confidence: 99%

Diastereoselective Cyclization of 1,5‐Dienes with the C−H Bond of Pyridine Catalyzed by a Cationic Mono(phosphinoamide) Alkyl Scandium Complex

Chen

Song

et al. 2017

ChemCatChem

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The carbocyclization of non-conjugated dienes mediated by organometallicsi sa ni mportant reaction for the synthesis of a variety of carbocyclic derivatives, but the directa nnulation of dienes with an inert CÀHbond of asubstrate has remained unexplored to date. We herein report as eries of novel rare-earth dialkyl complexes bearing ap hosphinoamide anion and demonstrate that the combination of am ono(phosphinoamido)-ligated scandium dialkyl complex with B(C 6 F 5 ) 3 resultsi na ne xcellent catalyst for the cis-selective cyclization of 1,5-dienes with the ortho-C(sp 2 )ÀHb ond of pyridines to afford an ew family of pyridyl-functionalized 1,3-disubstituted cyclopentane derivatives containing monocyclic,bicyclic, spirocyclic, and heterocyclic skeletons in moderatet oexcellent yields with high diastereoselectivities (cis/trans up to 99:1).The cyclization of non-conjugated dienes prompted by organometallics has emergeda sap owerful methodt oc onvert simple, readilya ccessible substrates into more complex cyclic skeletons that exist widely in natural products and bioactive molecules. [1][2][3] In principle, the cyclization of dienesw ith the CÀHb onds of organic compounds is the most straightforward and atom-efficient route for the construction of C-substituted carbocyclic molecules. However,t he CÀH-activation-mediated annulation of dienes hasn ot been reported previously,d espite extensive studies on diene cyclizationc ombined with various transformationss uch as silylation, boration, hydrogenation, hydrogermylation, and carbometalation. [1b,c, 4-8] This is probably owing to the lack of as uitable catalyst that shows high activity not only for the CÀHa ctivation of an organic compound but also for the cyclization of ad iene.Some of us recently showed that cationic half-sandwich rare-earth alkyls served as efficient catalysts for the CÀHa ddition of heteroatom-containing aromatic compounds such as pyridines,a nisoles,a nd N,N-dimethylanilines to aw ider ange of C=Cb onds such as those in 1-alkenes, styrenes,a nd allenes; [9, 10] these catalysts were also found to be efficient for the cyclopolymerizationo f1 ,5-and 1,6-dienes. [11] We therefore envisioned that ac atalytic protocol based on the integration of theset wo processes might be feasible for the direct cyclization of dienes with the CÀHb onds of arenes mediated by an appropriate rare-earth complex. In these studies, we became interested in the analogous rare-earth complexes bearing noncyclopentadienyl (Cp) ligands such as phosphinoamides. [12,13] The h 2 -N-P coordinationm ode of ap hosphinoamide ligand could partly resemble the h 5 -bonding fashion of aC pl igand, but the catalytic potential of ac ationic phosphinoamido-ligated rare-earth alkyl species has remained unexplored to date. Herein, we reportt he first mono(phosphinoamido)-ligated rare-earth dialkyl complexesa nd their application in catalytic pyridine CÀHa ddition/diene cyclization reactions. We found that ac ationic alkyl scandium species bearing mono(phosphinoamide) ligands generated from ne...

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Scandium-Catalyzed Cyclocopolymerization of 1,5-Hexadiene with Styrene and Ethylene: Efficient Synthesis of Cyclopolyolefins Containing Syndiotactic Styrene–Styrene Sequences and Methylene-1,3-cyclopentane Units

Abstract: |Macromolecules 2011, 44, 6335-6344 Macromolecules ARTICLE ' ASSOCIATED CONTENTb S Supporting Information. GPC curve, NMR spectra, and DSC charts of representative polymer products. This material is available free of charge via the Internet at http://pubs.acs.org.

Cited by 77 publications

References 63 publications

The Influence of Ziegler-Natta and Metallocene Catalysts on Polyolefin Structure, Properties, and Processing Ability

The Influence of Ziegler-Natta and Metallocene Catalysts on Polyolefin Structure, Properties, and Processing Ability

Synthesis of amino‐containing syndiotactic polystyrene as efficient polymer support for palladium nanoparticles

Diastereoselective Cyclization of 1,5‐Dienes with the C−H Bond of Pyridine Catalyzed by a Cationic Mono(phosphinoamide) Alkyl Scandium Complex

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