The Experts below are selected from a list of 786 Experts worldwide ranked by ideXlab platform
Jean-luc Vasse - One of the best experts on this subject based on the ideXlab platform.
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Sequential Hydrozirconation/Cyclization of Dienes, a New Route toward Trans 2-Substituted Vinylcyclopentanes
Organic Letters, 2014Co-Authors: Sebastien Clergue, Jean-luc VasseAbstract:The diastereoselective synthesis of trans-2-substituted vinylcyclopentanes is described. The method is based on the intramolecular coupling of 7-methoxy-1,5-dienes involving a sequential activation of the C═C double bonds via Hydrozirconation and TMSOTf-promoted allylation.
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sequential Hydrozirconation cyclization of dienes a new route toward trans 2 substituted vinylcyclopentanes
Organic Letters, 2014Co-Authors: Sebastien Clergue, Jean-luc VasseAbstract:The diastereoselective synthesis of trans-2-substituted vinylcyclopentanes is described. The method is based on the intramolecular coupling of 7-methoxy-1,5-dienes involving a sequential activation of the C═C double bonds via Hydrozirconation and TMSOTf-promoted allylation.
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A Hydrozirconation/iodination-mediated access to tetrahydroquinolizinium salts. Application to the synthesis of Lupinine and (−)-Epiquinamide
Tetrahedron Letters, 2013Co-Authors: Majdi Hajri, Jean-luc Vasse, Clement Blondelle, Agathe Martinez, Jan SzymoniakAbstract:The preparation of tetrahydroquinolizinium salts, based on a Hydrozirconation/iodination sequence involving 2-pyridyl alkenes, is presented. This approach was applied to the synthesis of substituted quinolizines as illustrated by the synthesis of Lupinine and (−)-Epiquinamide.
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a Hydrozirconation iodination mediated access to tetrahydroquinolizinium salts application to the synthesis of lupinine and epiquinamide
Tetrahedron Letters, 2013Co-Authors: Majdi Hajri, Jean-luc Vasse, Clement Blondelle, Agathe Martinez, Jan SzymoniakAbstract:The preparation of tetrahydroquinolizinium salts, based on a Hydrozirconation/iodination sequence involving 2-pyridyl alkenes, is presented. This approach was applied to the synthesis of substituted quinolizines as illustrated by the synthesis of Lupinine and (−)-Epiquinamide.
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Diastereoselective Access to Nonracemic 2-cis-Substituted and 2,6-cis-Disubstituted Piperidines.
ChemInform, 2012Co-Authors: Nicolas Coia, Jean-luc Vasse, Naima Mokhtari, Jan SzymoniakAbstract:Access to enantiopure amino ketones (III) and (X) via a Hydrozirconation/transmetalation/ acylation sequence of protected 1-aminobut-3-enes (I) and (X) is reported.
Jan Szymoniak - One of the best experts on this subject based on the ideXlab platform.
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A Hydrozirconation/iodination-mediated access to tetrahydroquinolizinium salts. Application to the synthesis of Lupinine and (−)-Epiquinamide
Tetrahedron Letters, 2013Co-Authors: Majdi Hajri, Jean-luc Vasse, Clement Blondelle, Agathe Martinez, Jan SzymoniakAbstract:The preparation of tetrahydroquinolizinium salts, based on a Hydrozirconation/iodination sequence involving 2-pyridyl alkenes, is presented. This approach was applied to the synthesis of substituted quinolizines as illustrated by the synthesis of Lupinine and (−)-Epiquinamide.
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a Hydrozirconation iodination mediated access to tetrahydroquinolizinium salts application to the synthesis of lupinine and epiquinamide
Tetrahedron Letters, 2013Co-Authors: Majdi Hajri, Jean-luc Vasse, Clement Blondelle, Agathe Martinez, Jan SzymoniakAbstract:The preparation of tetrahydroquinolizinium salts, based on a Hydrozirconation/iodination sequence involving 2-pyridyl alkenes, is presented. This approach was applied to the synthesis of substituted quinolizines as illustrated by the synthesis of Lupinine and (−)-Epiquinamide.
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Diastereoselective Access to Nonracemic 2-cis-Substituted and 2,6-cis-Disubstituted Piperidines.
ChemInform, 2012Co-Authors: Nicolas Coia, Jean-luc Vasse, Naima Mokhtari, Jan SzymoniakAbstract:Access to enantiopure amino ketones (III) and (X) via a Hydrozirconation/transmetalation/ acylation sequence of protected 1-aminobut-3-enes (I) and (X) is reported.
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access to enantiomerically enriched cis 2 3 disubstituted azetidines via diastereoselective Hydrozirconation
ChemInform, 2011Co-Authors: Tarun K Pradhan, Jean-luc Vasse, Syam K Krishnan, Jan SzymoniakAbstract:The reaction proceeds in three steps including Hydrozirconation/iodination/cyclization and affords the target azetidines mostly with excellent diastereoselectivity.
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Access to Enantiomerically Enriched cis‐2,3‐Disubstituted Azetidines via Diastereoselective Hydrozirconation.
ChemInform, 2011Co-Authors: Tarun K Pradhan, Jean-luc Vasse, K. Syam Krishnan, Jan SzymoniakAbstract:The reaction proceeds in three steps including Hydrozirconation/iodination/cyclization and affords the target azetidines mostly with excellent diastereoselectivity.
Tao Tang - One of the best experts on this subject based on the ideXlab platform.
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Hydrozirconated styrene copolymer as a macroinitiator to in situ synthesize polyethylene/polystyrene-g-polyethylene alloy via coordination polymerization
Polymer, 2017Co-Authors: Yanhui Wang, Jun Zheng, Lin Ye, Zi'an Chen, Tao TangAbstract:Abstract A new method to in situ synthesize polyethylene/polystyrene-g-polyethylene (PE/PS-g-PE) alloy based on Hydrozirconation reaction with Cp2ZrHCl and coordination polymerization was reported. Hydrozirconation of vinyl-containing polystyrene (copolymer of styrene and 4-(vinylphenyl)-1-butene (PSVS)) was found to be an efficient way for immobilization of zirconocene pre-initiator onto polymer backbone by carbon-zirconium (C-Zr) sigma (σ) bond. By activation with MAO, the resultant hydrozirconated PSVS could act as a macroinitiator with multiple-initiating sites (Zrδ+-Cδ-) for ethylene insertion and propagation in “graft from” fashion. The Hydrozirconation and the following ethylene polymerization were monitored by NMR and GPC, revealing the successful synthesis of PS-g-PE and the following formation of free PE chains due to chain transfer characteristic of metallocene catalyst. Thus we could prepare PE/PS-g-PE alloy through in situ ethylene polymerization by this method. The presence of PS-g-PE in the resultant alloy endowed some special functionalization, for example, acting as compatibilizer in PE/PS blends.
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surface coordination polymerization of ethylene by Hydrozirconation immobilized metallocene
Macromolecular Rapid Communications, 2014Co-Authors: Jun Zheng, Yanhui Wang, Lin Ye, Tao Tang, Jidong ZhangAbstract:Hydrozirconation on vinyl-terminated substrates (silicon wafer and nanosilica sphere) is employed as an efficient way for immobilization of zirconocene catalyst through Zr-C bonds, which is applied in surface coordination ethylene polymerization producing surface-tethered polyethylene (PE). The formation of Zr-C sigma bond induced by Hydrozirconation provides an initiator precursor for growing a layer of PE covalently linked onto substrates. The results from SEM, AFM, and TEM show that the surface polymerization is controlled by Hydrozirconation. Surface pattern or core-shell structure with crystalline PE coating can be formed, when silicon wafer is selectively functionalized with vinyl-groups or vinyl-modified nanosilica is applied. It is believed that Hydrozirconation for the synthesis of zirconocene initiator can be a versatile route to prepare polyolefin hybrid materials.
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Surface Coordination Polymerization of Ethylene by Hydrozirconation‐Immobilized Metallocene
Macromolecular Rapid Communications, 2014Co-Authors: Jun Zheng, Yanhui Wang, Lin Ye, Tao Tang, Jidong ZhangAbstract:Hydrozirconation on vinyl-terminated substrates (silicon wafer and nanosilica sphere) is employed as an efficient way for immobilization of zirconocene catalyst through Zr-C bonds, which is applied in surface coordination ethylene polymerization producing surface-tethered polyethylene (PE). The formation of Zr-C sigma bond induced by Hydrozirconation provides an initiator precursor for growing a layer of PE covalently linked onto substrates. The results from SEM, AFM, and TEM show that the surface polymerization is controlled by Hydrozirconation. Surface pattern or core-shell structure with crystalline PE coating can be formed, when silicon wafer is selectively functionalized with vinyl-groups or vinyl-modified nanosilica is applied. It is believed that Hydrozirconation for the synthesis of zirconocene initiator can be a versatile route to prepare polyolefin hybrid materials.
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controlled chain scission of polybutadiene by the schwartz Hydrozirconation
Chemistry: A European Journal, 2013Co-Authors: Jun Zheng, Yanhui Wang, Tao TangAbstract:Controlled chain-scission of polybutadiene (PB), polyisoprene, and poly(styrene-co-butadiene), induced by bis(cyclopentadienyl) zirconium hydrochloride (Cp2ZrHCl), was revealed at room temperature. The chain-scission reaction of linear PB was studied by means of GPC, NMR spectroscopy, and MALDI-TOF-MS. It was confirmed that the molecular weights of degraded products were quasi-quantitatively controlled by Cp2ZrHCl loading, irrespective of the starting PB, whereas the microstructure of PB chains was crucial to the scission reaction. The Hydrozirconation of model molecules indicated that the existence of an internal double bond in compounds with multiple double bonds was essential for chain cleavage. The chain-cleavage mechanism was proposed to involve Hydrozirconation of internal double bonds in PB chains and beta-alkyl elimination. Furthermore, metallocene-catalyzed chain-scission by a chain-transfer reaction was developed. It is believed that the reported chain scission offers a promising pathway for end-group functionalization by chain cleavage and presents a new application of Schwartz's reagent.
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synthesis of diverse well defined functional polymers based on Hydrozirconation and subsequent anti markovnikov halogenation of 1 2 polybutadiene
Macromolecules, 2012Co-Authors: Jun Zheng, Zhijie Zhang, Guangchun Zhang, Lu Wang, Tao TangAbstract:For the first time, Hydrozirconation and halogenolysis of 1,2-polybutadiene (1,2-PBD, by living anionic polymerization) were studied to synthesize reactive poly-halohydrocarbons, which provide a platform for preparing well-defined functional polymers via macromolecular substitution. Hrirozirconation and halogenolysis afforded quite convenience for anti-Markovnikov hydrohalogenation of 1,2-PBD with controllable degree of functionalization. Diverse functional polymers and branched polymers were synthesized after macromolecular substitution reaction with a broad range of commercially available nucleophiles (amines, phenols, alcohols, carbanions, carboxylates, and azide) or macromolecular nucleophiles. NMR and GPC characterizations confirmed high conversion in substitution reaction and narrow molecular weight distribution of the resultant functional polymers, respectively. The methodology utilizing Schwartz's reagent for Hydrozirconation of macromolecules could greatly facilitate the modification of vinyl groups containing polymers with high efficiency.
Jun Zheng - One of the best experts on this subject based on the ideXlab platform.
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Hydrozirconated styrene copolymer as a macroinitiator to in situ synthesize polyethylene/polystyrene-g-polyethylene alloy via coordination polymerization
Polymer, 2017Co-Authors: Yanhui Wang, Jun Zheng, Lin Ye, Zi'an Chen, Tao TangAbstract:Abstract A new method to in situ synthesize polyethylene/polystyrene-g-polyethylene (PE/PS-g-PE) alloy based on Hydrozirconation reaction with Cp2ZrHCl and coordination polymerization was reported. Hydrozirconation of vinyl-containing polystyrene (copolymer of styrene and 4-(vinylphenyl)-1-butene (PSVS)) was found to be an efficient way for immobilization of zirconocene pre-initiator onto polymer backbone by carbon-zirconium (C-Zr) sigma (σ) bond. By activation with MAO, the resultant hydrozirconated PSVS could act as a macroinitiator with multiple-initiating sites (Zrδ+-Cδ-) for ethylene insertion and propagation in “graft from” fashion. The Hydrozirconation and the following ethylene polymerization were monitored by NMR and GPC, revealing the successful synthesis of PS-g-PE and the following formation of free PE chains due to chain transfer characteristic of metallocene catalyst. Thus we could prepare PE/PS-g-PE alloy through in situ ethylene polymerization by this method. The presence of PS-g-PE in the resultant alloy endowed some special functionalization, for example, acting as compatibilizer in PE/PS blends.
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surface coordination polymerization of ethylene by Hydrozirconation immobilized metallocene
Macromolecular Rapid Communications, 2014Co-Authors: Jun Zheng, Yanhui Wang, Lin Ye, Tao Tang, Jidong ZhangAbstract:Hydrozirconation on vinyl-terminated substrates (silicon wafer and nanosilica sphere) is employed as an efficient way for immobilization of zirconocene catalyst through Zr-C bonds, which is applied in surface coordination ethylene polymerization producing surface-tethered polyethylene (PE). The formation of Zr-C sigma bond induced by Hydrozirconation provides an initiator precursor for growing a layer of PE covalently linked onto substrates. The results from SEM, AFM, and TEM show that the surface polymerization is controlled by Hydrozirconation. Surface pattern or core-shell structure with crystalline PE coating can be formed, when silicon wafer is selectively functionalized with vinyl-groups or vinyl-modified nanosilica is applied. It is believed that Hydrozirconation for the synthesis of zirconocene initiator can be a versatile route to prepare polyolefin hybrid materials.
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Surface Coordination Polymerization of Ethylene by Hydrozirconation‐Immobilized Metallocene
Macromolecular Rapid Communications, 2014Co-Authors: Jun Zheng, Yanhui Wang, Lin Ye, Tao Tang, Jidong ZhangAbstract:Hydrozirconation on vinyl-terminated substrates (silicon wafer and nanosilica sphere) is employed as an efficient way for immobilization of zirconocene catalyst through Zr-C bonds, which is applied in surface coordination ethylene polymerization producing surface-tethered polyethylene (PE). The formation of Zr-C sigma bond induced by Hydrozirconation provides an initiator precursor for growing a layer of PE covalently linked onto substrates. The results from SEM, AFM, and TEM show that the surface polymerization is controlled by Hydrozirconation. Surface pattern or core-shell structure with crystalline PE coating can be formed, when silicon wafer is selectively functionalized with vinyl-groups or vinyl-modified nanosilica is applied. It is believed that Hydrozirconation for the synthesis of zirconocene initiator can be a versatile route to prepare polyolefin hybrid materials.
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controlled chain scission of polybutadiene by the schwartz Hydrozirconation
Chemistry: A European Journal, 2013Co-Authors: Jun Zheng, Yanhui Wang, Tao TangAbstract:Controlled chain-scission of polybutadiene (PB), polyisoprene, and poly(styrene-co-butadiene), induced by bis(cyclopentadienyl) zirconium hydrochloride (Cp2ZrHCl), was revealed at room temperature. The chain-scission reaction of linear PB was studied by means of GPC, NMR spectroscopy, and MALDI-TOF-MS. It was confirmed that the molecular weights of degraded products were quasi-quantitatively controlled by Cp2ZrHCl loading, irrespective of the starting PB, whereas the microstructure of PB chains was crucial to the scission reaction. The Hydrozirconation of model molecules indicated that the existence of an internal double bond in compounds with multiple double bonds was essential for chain cleavage. The chain-cleavage mechanism was proposed to involve Hydrozirconation of internal double bonds in PB chains and beta-alkyl elimination. Furthermore, metallocene-catalyzed chain-scission by a chain-transfer reaction was developed. It is believed that the reported chain scission offers a promising pathway for end-group functionalization by chain cleavage and presents a new application of Schwartz's reagent.
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synthesis of diverse well defined functional polymers based on Hydrozirconation and subsequent anti markovnikov halogenation of 1 2 polybutadiene
Macromolecules, 2012Co-Authors: Jun Zheng, Zhijie Zhang, Guangchun Zhang, Lu Wang, Tao TangAbstract:For the first time, Hydrozirconation and halogenolysis of 1,2-polybutadiene (1,2-PBD, by living anionic polymerization) were studied to synthesize reactive poly-halohydrocarbons, which provide a platform for preparing well-defined functional polymers via macromolecular substitution. Hrirozirconation and halogenolysis afforded quite convenience for anti-Markovnikov hydrohalogenation of 1,2-PBD with controllable degree of functionalization. Diverse functional polymers and branched polymers were synthesized after macromolecular substitution reaction with a broad range of commercially available nucleophiles (amines, phenols, alcohols, carbanions, carboxylates, and azide) or macromolecular nucleophiles. NMR and GPC characterizations confirmed high conversion in substitution reaction and narrow molecular weight distribution of the resultant functional polymers, respectively. The methodology utilizing Schwartz's reagent for Hydrozirconation of macromolecules could greatly facilitate the modification of vinyl groups containing polymers with high efficiency.
Xian Huang - One of the best experts on this subject based on the ideXlab platform.
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Studies on Hydrozirconation of 1-alkynyl sulfoxides or sulfones and the application for the synthesis of stereodefined vinyl sulfoxides or sulfones.
Journal of Organic Chemistry, 2003Co-Authors: Xian Huang, De‐hui Duan, Weixin ZhengAbstract:The Hydrozirconation reaction of 1-alkynyl sulfoxides or sulfones with Cp2Zr(H)Cl in THF at room temperature predominantly gave Z-β-zirconated vinyl sulfoxides or sulfones with excellent regioselectivity. Compared with 1-alkynyl sulfoxides, the Hydrozirconation reaction of 1-alkynyl sulfones exhibits great synthetic potential, leading to the efficient preparation of Z-β-halovinyl sulfones, Z-β-sulfonyl α,β-unsaturated ketones, and Z-β-alkynyl vinyl sulfones. Although the reaction mechanisms are still not clear, the neighboring group participation of the sulfinyl or sulfonyl group may be playing an important role in this unique Hydrozirconation reaction.
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stereoselective synthesis of substituted allyl selenide by the reaction of e 3 selanyl vinylzirconocene chloride with aldehydes or acyl chlorides
Journal of Chemical Research-s, 2003Co-Authors: Xian HuangAbstract:A regio- and stereoselective synthesis of substituted allyl selenides is described. Hydrozirconation of propargyl selenides and its further reaction with aldehydes or acyl chlorides afford 4-selanyl allyl alcohols or 4-selanyl-2-en-1-one, respectively.
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stereoselective synthesis of e 2 alkyl and 2 phenyl 1 silylvinyl sulfides via Hydrozirconation of alkyl silyl acetylenes
Journal of Chemical Research-s, 2000Co-Authors: Ping Zhong, Xian HuangAbstract:Hydrozirconation of alkyl silyl acetylenes gave organozirconium complexes, which reacted with aryl or alkyl sulfonyl chlorides to afford (E)-1-silylvinyl sulfides in high yields.
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STEREOSELECTIVE SYNTHESIS OF (E)-VINYLSULFIDES VIA THE REACTION OF VINYLZIRCONIUM COMPOUNDS WITH DISULFIDES
Synthetic Communications, 1999Co-Authors: Xian Huang, Xinhua Xu, Weixin ZhengAbstract:Abstract Hydrozirconation of alk-1-ynes gives vinyl zirconium complexes, which react with disulfides to afford (E)-vinylic sulfides in high yield.
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Hydrozirconation of alkynyl(phenyl)iodonium salts and stereoselective synthesis of (E)-trisubstituted olefins
Journal of The Chemical Society-perkin Transactions 1, 1999Co-Authors: Xian Huang, Junhua Wang, De-yu YangAbstract:Hydrozirconation of alkynyl(phenyl)iodonium salts affords alkenylchlorozirconocenes with the Zr-C bond germinal to the iodonium moiety, and two subsequent substitution reactions proceed with retention of the configuration of the carbon-carbon double bond.