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John F Hartwig - One of the best experts on this subject based on the ideXlab platform.
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Mechanistic Studies of Copper-Catalyzed Asymmetric Hydroboration of Alkenes
Journal of the American Chemical Society, 2017Co-Authors: Yumeng Xi, John F HartwigAbstract:Mechanistic studies of the copper-catalyzed asymmetric hydroboration of Vinylarenes and internal alkenes are reported. Catalytic systems with both DTBM-SEGPHOS and SEGPHOS as the ligands have been investigated. With DTBM-SEGPHOS as the ligand, the resting state of the catalyst, which is also a catalytic intermediate, for hydroboration of 4-fluorostyrene is a phenethylcopper(I) complex ligated by the bisphosphine. This complex was fully characterized by NMR spectroscopy and X-ray crystallography. The turnover-limiting step in the catalytic cycle for the reaction of Vinylarenes is the borylation of this phenethylcopper complex with pinacolborane (HBpin) to form the boronate ester product and a copper hydride. Experiments showed that the borylation occurs with retention of configuration at the benzylic position. β-Hydrogen elimination and insertion of the alkene to reform this phenethylcopper complex is reversible in the absence of HBpin but is irreversible during the catalytic process because reaction with ...
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Direct measurement of the thermodynamics of Vinylarene hydroamination.
Journal of the American Chemical Society, 2006Co-Authors: Adam M. Johns, Norio Sakai, And André Ridder, John F HartwigAbstract:The thermodynamics for intermolecular hydroamination of Vinylarenes with arylamines have been measured directly by conducting the addition processes, as well as cleavage of the addition products, under conditions in which amine, Vinylarene, and phenethylamine are all present. The reaction of N-methylaniline with styrene is exothermic by about 10 kcal/mol but nearly thermoneutral in free energy. The free energies for additions of various primary arylamines to styrene and for additions of primary arylamines to indene, dihydronaphthalene, and two Vinylarenes range from 1.3 to -3.5 kcal/mol (K = 0.16-155 M-1). The steric properties of the nucleophile significantly influenced the equilibrium constant for addition, but the electronic properties of the nucleophile had a minor effect on this equilibrium constant. These measurements have led to the first successful intermolecular addition of aniline to indene and 1,2-dihydronaphthalene and shed light on factors requiring consideration when choosing substrates and reaction conditions for this transformation.
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a highly active palladium catalyst for intermolecular hydroamination factors that control reactivity and additions of functionalized anilines to dienes and Vinylarenes
Journal of the American Chemical Society, 2006Co-Authors: Adam M. Johns, Masaru Utsunomiya, Christopher D Incarvito, John F HartwigAbstract:We report a catalyst for intermolecular hydroamination of Vinylarenes that is substantially more active for this process than catalysts published previously. With this more reactive catalyst, we demonstrate that additions of amines to Vinylarenes and dienes occur in the presence of potentially reactive functional groups, such as ketones with enolizable hydrogens, free alcohols, free carboxylic acids, free amides, nitriles, and esters. The catalyst for these reactions is generated from [Pd(η3-allyl)Cl]2 (with or without added AgOTf) or [Pd(CH3CN)4](BF4)2 and Xantphos (9,9-dimethyl-4,5-bis(diphenylphosphino)xanthene), which generates complexes with large P−Pd−P bite angles. Studies on the rate of the C−N bond-forming step that occurs by attack of amine on an η3-phenethyl and an η3-allyl complex were conducted to determine the effect of the bite angle on the rate of this nucleophilic attack. Studies on model η3-benzyl complexes containing various bisphosphines showed that the nucleophilic attack was faster f...
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intermolecular markovnikov hydroamination of Vinylarenes with alkylamines
Journal of the American Chemical Society, 2003Co-Authors: Masaru Utsunomiya, John F HartwigAbstract:A transition metal-catalyzed intermolecular hydroamination of Vinylarenes with alkylamines is reported. The combination of Pd(O2CCF3)4, DPPF, and TfOH was the most effective catalyst of those tested. Control experiments without palladium, acid, or ligand all occurred in low yield. The reaction of various Vinylarenes with cyclic and acyclic alkylamines in the presence of 5 mol % of this catalyst formed the corresponding arylethylamine products in moderate to high yields. For example, reactions of morpholine, 4-phenylpiperazine, 4-Boc-piperazine, isoindoline, and tetrahydroisoquinoline with styrene all occurred in 58−75% yield. Acyclic amines such as N-benzylmethylamine and n-hexylmethylamine reacted with 2-vinylnaphthalene in 63% and 53% yields, respectively. Mechanistic investigations showed that the reaction occurred through an η3-arylethyl palladium complex. The reactions of this complex with alkylamines generated product in combination with regenerating free Vinylarene, Pd(0), and ammonium salt. Thus, ...
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Rhodium-catalyzed anti-Markovnikov hydroamination of Vinylarenes.
Journal of the American Chemical Society, 2003Co-Authors: Masaru Utsunomiya, Ryoichi Kuwano, Motoi Kawatsura, John F HartwigAbstract:The transition metal-catalyzed anti-Markovnikov hydroamination of unactivated Vinylarenes with a rhodium complex of DPEphos is reported. The reaction of electron-neutral or electron-rich Vinylarenes with a variety of secondary amines in the presence of catalyst forms the products from anti-Markovnikov hydroamination in high yields. Reactions of morpholine, N-phenylpiperazine, N-Boc-piperazine, piperidine, 2,5-dimethylmorpholine, and perhydroisoquinoline reacted with styrene to form the amine product in 51-71% yield. Reactions of a variety of Vinylarenes with morpholine generated amine as the major product. Reactions of morpholine with electron-poor Vinylarenes gave lower amine:enamine ratios than reactions of electron-rich Vinylarenes at the same concentration of Vinylarene, but conditions were developed with lower concentrations of electron-poor Vinylarene to maintain formation of the amine as the major product. Reactions of dimethylamine with Vinylarenes were fast and formed amine as the major product. Mechanistic studies on the hydroamination process showed that the amine:enamine ratio was lower for reactions conducted with higher concentrations of Vinylarene and that one Vinylarene influences the selectivity for reaction of another. A mechanism proceeding through a metallacyclic intermediate that opens in the presence of a second Vinylarene accounts for these and other mechanistic observations.
Kyoko Nozaki - One of the best experts on this subject based on the ideXlab platform.
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Vinylarene co copolymerization and Vinylarene polar vinyl monomer co terpolymerization using palladium phosphine sulfonate catalysts
Chemistry-an Asian Journal, 2011Co-Authors: Takeharu Kageyama, Shingo Ito, Kyoko NozakiAbstract:Palladium/phosphine-sulfonate complexes were effective for the alternating copolymerization of Vinylarenes with carbon monoxide (CO). The obtained copolymers had iso-enriched microstructures with ll selectivity of up to circa 60 %. The catalytic system was successfully applied to the terpolymerization of Vinylarene and polar vinyl monomers with CO to produce novel terpolymers, which could not be obtained by using previously developed catalysts. NMR and DSC analyses suggested that Vinylarene/CO units and polar vinyl monomer/CO units were randomly distributed in the terpolymer main chains.
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Vinylarene/CO Copolymerization and Vinylarene/Polar Vinyl Monomer/CO Terpolymerization Using Palladium/Phosphine‐Sulfonate Catalysts
Chemistry an Asian journal, 2011Co-Authors: Takeharu Kageyama, Shingo Ito, Kyoko NozakiAbstract:Palladium/phosphine-sulfonate complexes were effective for the alternating copolymerization of Vinylarenes with carbon monoxide (CO). The obtained copolymers had iso-enriched microstructures with ll selectivity of up to circa 60 %. The catalytic system was successfully applied to the terpolymerization of Vinylarene and polar vinyl monomers with CO to produce novel terpolymers, which could not be obtained by using previously developed catalysts. NMR and DSC analyses suggested that Vinylarene/CO units and polar vinyl monomer/CO units were randomly distributed in the terpolymer main chains.
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Hydroesterification of Vinylarenes Catalyzed by Palladium Complexes of Dialkylmonoaryl- and Monoalkyldiarylphosphines
Bulletin of the Chemical Society of Japan, 2004Co-Authors: Yasutoyo Kawashima, Kyoko Nozaki, Kentaro Okano, Tamejiro HiyamaAbstract:Hydroesterification of Vinylarenes using a mixture of PdCl2 and monodentate phosphorus ligands as a catalyst was studied. As ligands, menthyldiphenylphosphine (MDPP), neomenthyldiphenylphosphine (N...
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liquid crystalline stereoregular polyketone prepared from a mesogenic Vinylarene and carbon monoxide
Journal of Polymer Science Part A, 2003Co-Authors: Yasutoyo Kawashima, Kyoko Nozaki, Tamejiro Hiyama, Masafumi Yoshio, Kiyoshi Kanie, Takashi KatoAbstract:Isotactic and syndiotactic polyketones were synthesized by the alternating copolymerizations of a mesogenic Vinylarene, 4-cyano-4'-[8-(4-vinylphenyl)octyl-1-oxy]-biphenyl, with carbon monoxide, and this revealed the influence of backbone tacticity on their thermal properties. The isotactic polyketone was an amorphous polymer that did not show any mesophase, whereas the syndiotactic polyketone exhibited liquid crystallinity.
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Liquid‐crystalline stereoregular polyketone prepared from a mesogenic Vinylarene and carbon monoxide
Journal of Polymer Science Part A, 2003Co-Authors: Yasutoyo Kawashima, Kyoko Nozaki, Tamejiro Hiyama, Masafumi Yoshio, Kiyoshi Kanie, Takashi KatoAbstract:Isotactic and syndiotactic polyketones were synthesized by the alternating copolymerizations of a mesogenic Vinylarene, 4-cyano-4'-[8-(4-vinylphenyl)octyl-1-oxy]-biphenyl, with carbon monoxide, and this revealed the influence of backbone tacticity on their thermal properties. The isotactic polyketone was an amorphous polymer that did not show any mesophase, whereas the syndiotactic polyketone exhibited liquid crystallinity.
Qi-lin Zhou - One of the best experts on this subject based on the ideXlab platform.
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Nickel-Catalyzed Highly Selective Hydrovinylation of α-Ketals of Vinylarenes
Advanced Synthesis & Catalysis, 2008Co-Authors: Qi Zhang, Li‐xin Wang, Shou-fei Zhu, Xiang‐chen Qiao, Qi-lin ZhouAbstract:A nickel-catalyzed hydrovinylation of α-ketal derivatives of Vinylarenes has been developed, providing a new method for preparing functional olefins with a quarternary carbon center in high yields and selectivities.
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Highly Enantioselective Hydrovinylation of α-Alkyl Vinylarenes. An Approach to the Construction of All-Carbon Quaternary Stereocenters
Journal of the American Chemical Society, 2006Co-Authors: Wen-jian Shi, Jian-hua Xie, Shou-fei Zhu, Qi Zhang, Guo-hua Hou, Qi-lin ZhouAbstract:The highly enantioselective hydrovinylation of α-alkyl Vinylarenes was realized by using nickel complexes of chiral spiro phosphoramidite ligands. The method provided a new approach to the construction of chiral all-carbon quaternary centers.
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Palladium-catalyzed asymmetric hydrovinylation under mild conditions using monodentate chiral spiro phosphoramidite and phosphite ligands
Tetrahedron: Asymmetry, 2005Co-Authors: Wen-jian Shi, Jian-hua Xie, Qi-lin ZhouAbstract:Palladium complexes of chiral spiro phosphoramidite and phosphite ligands are effective catalysts in the asymmetric hydrovinylation of Vinylarenes with ethylene. The hydrovinylation products were obtained in modest selectivity with enantioselectivities up to 92% ee. The structures of the palladium catalysts have been analyzed by X-ray diffraction. The active catalyst contained one monodentate ligand. A kinetic resolution accompanied the isomerization of the hydrovinylation product in the reaction.
Debabrata Maiti - One of the best experts on this subject based on the ideXlab platform.
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Orthogonal Selectivity in C–H Olefination: Synthesis of Branched Vinylarene with Unactivated Aliphatic Substitution
ACS Catalysis, 2019Co-Authors: Soumitra Agasti, Bhaskar Mondal, Tapas Kumar Achar, Soumya Kumar Sinha, Anjana Sarala Suseelan, Kálmán J. Szabó, Franziska Schoenebeck, Debabrata MaitiAbstract:Oxidative coupling is a useful tool to synthesize Vinylarenes. Despite remarkable successes in linear Vinylarene, branched Vinylarene synthesis has remained underdeveloped. Overcoming this limitation, herein, we report a chelation-assisted oxidative coupling to generate branched olefinated product in high yield. Exclusive branched selectivity was obtained using alkenyl carboxylic acid. Detailed experimental studies combined with computational investigations suggest that β-migratory insertion, followed by a decarboxylation pathway is operative for the overall transformation.
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orthogonal selectivity in c h olefination synthesis of branched Vinylarene with unactivated aliphatic substitution
ACS Catalysis, 2019Co-Authors: Soumitra Agasti, Bhaskar Mondal, Tapas Kumar Achar, Soumya Kumar Sinha, Anjana Sarala Suseelan, Kálmán J. Szabó, Franziska Schoenebeck, Debabrata MaitiAbstract:Oxidative coupling is a useful tool to synthesize Vinylarenes. Despite remarkable successes in linear Vinylarene, branched Vinylarene synthesis has remained underdeveloped. Overcoming this limitation, herein, we report a chelation-assisted oxidative coupling to generate branched olefinated product in high yield. Exclusive branched selectivity was obtained using alkenyl carboxylic acid. Detailed experimental studies combined with computational investigations suggest that β-migratory insertion, followed by a decarboxylation pathway is operative for the overall transformation.
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Orthogonal Selectivity in C–H Olefination : Synthesis of Branched Vinylarene with Unactivated Aliphatic Substitution
ACS Catalysis, 2019Co-Authors: Soumitra Agasti, Bhaskar Mondal, Tapas Kumar Achar, Soumya Kumar Sinha, Anjana Sarala Suseelan, Kálmán J. Szabó, Franziska Schoenebeck, Debabrata MaitiAbstract:Oxidative coupling is a useful tool to synthesize Vinylarenes. Despite remarkable successes in linear Vinylarene, branched Vinylarene synthesis has remained underdeveloped. Overcoming this limitati...
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orthogonal selectivity in c h olefination synthesis of branched Vinylarene with unactivated aliphatic substitution
ACS Catalysis, 2019Co-Authors: Soumitra Agasti, Bhaskar Mondal, Tapas Kumar Achar, Soumya Kumar Sinha, Anjana Sarala Suseelan, Kálmán J. Szabó, Franziska Schoenebeck, Debabrata MaitiAbstract:Oxidative coupling is a useful tool to synthesize Vinylarenes. Despite remarkable successes in linear Vinylarene, branched Vinylarene synthesis has remained underdeveloped. Overcoming this limitati...
Tamejiro Hiyama - One of the best experts on this subject based on the ideXlab platform.
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Nickel-Catalyzed Hydroheteroarylation of Vinylarenes.
ChemInform, 2010Co-Authors: Yoshiaki Nakao, Natsuko Kashihara, Kyalo Stephen Kanyiva, Tamejiro HiyamaAbstract:In the presence of a nickel/carbene catalyst, the hydroheteroarylation of Vinylarenes with indoles, benzimidazoles, and analogues affords exclusively 1-aryl-1-heteroarylethanes.
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Nickel-catalyzed alkenylation and alkylation of fluoroarenes via activation of C-H bond over C-F bond.
Journal of the American Chemical Society, 2008Co-Authors: Yoshiaki Nakao, Natsuko Kashihara, Kyalo Stephen Kanyiva, Tamejiro HiyamaAbstract:Nickel/P(c-C5H9)3 (PCyp3) catalyst effects the addition reactions of fluoroarenes across alkynes, 1,3-dienes, and Vinylarenes via the activation of C−H bonds over C−F bonds. The acidic C−H bonds located ortho to fluorine are exclusively activated to afford a range of alkenylated and alkylated fluoroarenes.
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Hydroesterification of Vinylarenes Catalyzed by Palladium Complexes of Dialkylmonoaryl- and Monoalkyldiarylphosphines
Bulletin of the Chemical Society of Japan, 2004Co-Authors: Yasutoyo Kawashima, Kyoko Nozaki, Kentaro Okano, Tamejiro HiyamaAbstract:Hydroesterification of Vinylarenes using a mixture of PdCl2 and monodentate phosphorus ligands as a catalyst was studied. As ligands, menthyldiphenylphosphine (MDPP), neomenthyldiphenylphosphine (N...
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liquid crystalline stereoregular polyketone prepared from a mesogenic Vinylarene and carbon monoxide
Journal of Polymer Science Part A, 2003Co-Authors: Yasutoyo Kawashima, Kyoko Nozaki, Tamejiro Hiyama, Masafumi Yoshio, Kiyoshi Kanie, Takashi KatoAbstract:Isotactic and syndiotactic polyketones were synthesized by the alternating copolymerizations of a mesogenic Vinylarene, 4-cyano-4'-[8-(4-vinylphenyl)octyl-1-oxy]-biphenyl, with carbon monoxide, and this revealed the influence of backbone tacticity on their thermal properties. The isotactic polyketone was an amorphous polymer that did not show any mesophase, whereas the syndiotactic polyketone exhibited liquid crystallinity.
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Liquid‐crystalline stereoregular polyketone prepared from a mesogenic Vinylarene and carbon monoxide
Journal of Polymer Science Part A, 2003Co-Authors: Yasutoyo Kawashima, Kyoko Nozaki, Tamejiro Hiyama, Masafumi Yoshio, Kiyoshi Kanie, Takashi KatoAbstract:Isotactic and syndiotactic polyketones were synthesized by the alternating copolymerizations of a mesogenic Vinylarene, 4-cyano-4'-[8-(4-vinylphenyl)octyl-1-oxy]-biphenyl, with carbon monoxide, and this revealed the influence of backbone tacticity on their thermal properties. The isotactic polyketone was an amorphous polymer that did not show any mesophase, whereas the syndiotactic polyketone exhibited liquid crystallinity.
