- Distorted Sandwich α-Diimine PdII Catalyst: Linear Polyethylene and Synthesis of Ethylene/Acrylate Elastomers
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The introduction of m-xylyl substituents to α-diimine PdII catalyst promotes living ethylene polymerization at room temperature and low pressure to yield high molecular weight polyethylene (PE) with low branching (a highly effective blockage to the axial sites of the catalytic center and form a distorted sandwich geometry. The shielding prevents chain-transfer and easy accessibility of polar monomers, leading to a living polymerization. Conducting a light irradiation as part of the one-step metal-organic insertion light initiated radical (MILRad) process leads to diblock copolymers of ethylene and acrylates. Incorporation of different acrylate block sequences can significantly modify the mechanical and chemical properties of block copolymers which can be modulated to be a hard plastic, elastomer, or semi-amorphous polymer.
- Liu, Yu-Sheng,Harth, Eva
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supporting information
p. 24107 - 24115
(2021/10/07)
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- Catalyst- And Silane-Controlled Enantioselective Hydrofunctionalization of Alkenes by Cobalt-Catalyzed Hydrogen Atom Transfer and Radical-Polar Crossover
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The catalytic enantioselective synthesis of tetrahydrofurans, which are found in the structures of many biologically active natural products, via a transition-metal-catalyzed hydrogen atom transfer (TM-HAT) and radical-polar crossover (RPC) mechanism is described herein. Hydroalkoxylation of nonconjugated alkenes proceeded efficiently with excellent enantioselectivity (up to 94% ee) using a suitable chiral cobalt catalyst, N-fluoro-2,4,6-collidinium tetrafluoroborate, and diethylsilane. Surprisingly, the absolute configuration of the product was highly dependent on the steric hindrance of the silane. Slow addition of the silane, the dioxygen effect on the solvent, thermal dependence, and DFT calculation results supported the unprecedented scenario of two competing selective mechanisms. For the less-hindered diethylsilane, a high concentration of diffused carbon-centered radicals invoked diastereoenrichment of an alkylcobalt(III) intermediate by a radical chain reaction, which eventually determined the absolute configuration of the product. On the other hand, a more hindered silane resulted in less opportunity for a radical chain reaction, instead facilitating enantioselective kinetic resolution during the late-stage nucleophilic displacement of the alkylcobalt(IV) intermediate.
- Ebisawa, Kousuke,Izumi, Kana,Ooka, Yuka,Kato, Hiroaki,Kanazawa, Sayori,Komatsu, Sayura,Nishi, Eriko,Shigehisa, Hiroki
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supporting information
p. 13481 - 13490
(2020/09/02)
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- Catalysts, ligands and use thereof
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According to the present invention, there is provided a catalytic complex comprising a metal, one or more ligands and one or more counterions, wherein said one or more ligands include a non-racemic chiral ligand and wherein said one or more counterions include a triflimide counterion. Also provided are methods of making said catalytic complex and processes for producing chiral compounds which involve the use of said catalytic complex. In addition, the present invention provides compounds of the formula (2) as defined herein. The compounds of formula (2) may be useful as ligands in catalytic complexes.
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Page/Page column 67; 68
(2017/05/17)
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- Crystal structures and isometricity comparison of methylated bisphenol F derivatives
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The syntheses and X-ray structures of three methylated bisphenol F derivatives and one respective analogue are reported. A special emphasis lies on the influence of methyl groups on the conformation of the common diphenylmethane scaffold. The introduction of four methyl groups to bisphenol F was found not to disturb its typical strong hydrogen bond network, and yet, to change the pattern of the aromatic interactions in the overall packing. According to the isometricity comparison, the addition of methyl groups to the diphenylmethane core has a greater influence on the conformation of the individual molecules, than the presence or absence of hydrogen bonding donors or acceptors.
- Gruber, Tobias,Nestler, Robert,Seichter, Wilhelm,Bombicz, Petra
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p. 319 - 325
(2013/12/04)
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- Steric tuning of C2-symmetric chiral N-heterocyclic carbene in gold-catalyzed asymmetric cyclization of 1,6-enynes
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Steric tuning of C2-symmetric chiral N-heterocyclic carbene (NHC) was performed in Au(I)-catalyzed asymmetric cyclization of 1,6-enyne. Higher enantioselectivity was realized when chiral NHC-AuCl/AgSbF6 catalysts whose N-substituent on the NHC overlays the Au-Cl bond was utilized.
- Yamada, Ken-Ichi,Matsumoto, Yasumasa,Selim, Khalid B.,Yamamoto, Yasutomo,Tomioka, Kiyoshi
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experimental part
p. 4159 - 4165
(2012/07/27)
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- Direct catalytic asymmetric aminoallylation of aldehydes: Synergism of chiral and nonchiral Bronsted acids
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The development of a catalytic asymmetric method for the direct aminoallylation of aldehydes is described that gives high asymmetric inductions for a broad range of substrates including both aromatic and aliphatic aldehydes. This method allows for direct isolation of unprotected analytically pure homoallylic amines without chromatography. The unique catalyst system developed for this process involves the synergistic interaction between a chiral and a nonchiral Bronsted acid.
- Ren, Hong,Wulff, William D.
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supporting information; experimental part
p. 5656 - 5659
(2011/06/18)
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- MODULATORS OF C3A RECEPTOR AND METHODS OF USE THEREOF
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Provided are compounds that are modulators of C3a receptor activity, compositions containing the compounds and methods of use of the compounds and compositions. In certain embodiments, the compounds are pyridones. In certain embodiments, provided are methods for treatment or amelioration of diseases associated with modulation of C3a receptor activity.
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Page/Page column 104
(2008/12/07)
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- Catalytic asymmetric epoxidation
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The present invention relates to the synthesis of chiral epoxides via a catalytic asymmetric oxidation of olefins. Additionally, the methodology provides a method of asymmetrically oxidizing sulfides and phosphines. This asymmetric oxidation employs a catalyst system composed of a metal and a chiral bishydroxamic acid ligand, which, in the presence of a stoichiometric oxidation reagent, serves to asymmetrically oxidize a variety of substrates.
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Page/Page column 27
(2010/02/12)
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