The Experts below are selected from a list of 264 Experts worldwide ranked by ideXlab platform
Rene Gree - One of the best experts on this subject based on the ideXlab platform.
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a tandem isomerization mannich reaction for the enantioselective synthesis of β Amino ketones and β Amino alcohols with applications as key intermediates for ent nikkomycins and ent funebrine
European Journal of Organic Chemistry, 2011Co-Authors: Thierry Roisnel, Alain Valleix, Rene GreeAbstract:P-Amino ketones, with a Primary Amino Group, are easily obtained in good yields and excellent enantioselectivities through a short sequence that involves, as a key step, a tandem isomerization-Mannich reaction from allylic alcohols with N-tert-butanesulfinimines. This method was used for the enantioselective synthesis of corresponding β-Amino alcohols and also for key intermediates in the preparation of ent-nikkomycins or ent-funebrine.
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Synthesis of β-Aminocyclohexanones and β-Aminocyclohexanols through an intramolecular tandem isomerization-Mannich reaction as a key step
SYNTHESIS, 2011Co-Authors: Hai Thuong Cao, Danielle Gree, Rene GreeAbstract:New β-Aminocyclohexanones and β-Aminocyclohexanols, with a Primary Amino Group, have been obtained by a short and efficient sequence involving an intramolecular tandem isomerization-Mannich reaction as the key step. This methodology takes advantage of tert-butanesulfinyl protection of the nitrogen atom.
M. H. Hyun - One of the best experts on this subject based on the ideXlab platform.
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liquid chromatographic enantioseparations on crown ether based chiral stationary phases
Journal of Chromatography A, 2016Co-Authors: M. H. HyunAbstract:Various liquid chromatographic chiral stationary phases (CSPs) have been developed for the resolution of racemic compounds. In particular, CSPs based on chiral crown ethers have been known to be useful in the resolution of racemic compounds containing a Primary Amino Group. In this paper, the development of two types of CSPs based on the chiral crown ethers containing 1,1'-binaphthyl unit(s) or tartaric acid units as chiral barrier(s) and their applications to the resolution of various racemic compounds were reviewed. The structural characteristics of eleven CSPs and their chromatographic behaviors for the resolution of racemic Primary Amino and non-Primary Amino compounds were included.
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Enantioseparations of Primary Amino compounds by high-performance liquid chromatography using chiral crown ether-based chiral stationary phase.
Methods in molecular biology (Clifton N.J.), 2012Co-Authors: M. H. HyunAbstract:Liquid chromatographic resolution of racemic compounds containing a Primary Amino Group has been known to be most successful when chiral crown ether-based chiral stationary phases (CSPs) are used. Among various crown ether-based CSPs, the stationary phase based on (+)-(18-crown-6)-2,3,11,12-tetracarboxylic acid covalently bonded to silica gel has been successfully applied in the resolution of various racemic compounds containing Primary Amino Groups. In this chapter, the preparation of the CSP based on (+)-(18-crown-6)-2,3,11,12-tetracarboxylic acid covalently bonded to silica gel and examples for the application to the enantioseparation of racemic compounds including α-Amino acids, cyclic amines, Amino alcohols, and chiral drugs are described.
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new chiral crown ether stationary phase for the liquid chromatographic resolution of α Amino acid enantiomers
Journal of Chromatography A, 2001Co-Authors: M. H. Hyun, S. C. Han, Bruce H Lipshutz, Youngjun Shin, Christopher J WelchAbstract:Abstract A new chiral stationary phase (CSP) for the liquid chromatographic separation of enantiomers was prepared by bonding a novel enantiopure (diphenyl-substituted 1,1′-binaphthyl) crown ether to 5 μm silica gel. The resulting CSP was applied to the separation of the enantiomers of various natural and unnatural α-Amino acids. All α-Amino acids tested were resolved very well on the new CSP, with the exception of proline, which does not contain a Primary Amino Group. The resolution of α-Amino acid enantiomers on this new CSP was found to be dependent on the type and amounts of organic and acidic modifiers, and on column temperature.
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liquid chromatographic resolution of racemic compounds containing a Primary Amino Group on a dynamic chiral stationary phase derived from chiral crown ether
Journal of Liquid Chromatography & Related Technologies, 2000Co-Authors: M. H. Hyun, J. S. Jin, Hye Jin Koo, W. LeeAbstract:A dynamic chiral stationary phase (CSP) prepared by hydrophobically bonding N-dodecyl diamide of (+)-(18-crown-6)-2,3,11,12-tetracarboxylic acid to octadecyl silica gel was successfully employed in resolving various racemic compounds containing a Primary Amino functional Group. The racemic compounds resolved on the CSP include α-Amino acids, α-Amino esters, Amino alcohols, amines, α-Aminocarbonyl compounds, and fluoroquinolone antibacterial agents. In order to see the effect of organic and acidic modifiers in the mobile phase and the temperature of the column on the enantioselectivity exerted by the CSP, five racemic compounds that resolved well on the CSP were selected and their resolutions were investigated with the variation of organic and acidic modifiers in the mobile phase and the temperature of the column. The results demonstrate that the chromatographic factors such as capacity factors (k'), separation factors (α), and resolution factors (RS) might be controlled, to some extent, by varying organic...
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Separation of the stereoisomers of racemic fluoroquinolone antibacterial agents on a crown-ether-based chiral HPLC stationary phase
Chromatographia, 2000Co-Authors: M. H. Hyun, S. C. Han, J. S. Jin, W. LeeAbstract:A chiral stationary phase derived from (+)-(18-crown-6)-2,3,11,12-tetracarboxylic acid has been successfully used for the direct separation of the enantiomers of recemic fluoroquinolines containing a Primary Amino Group being investigated as antibacterial agents. The chromatographic resolution behavior was found to depend on the content and the type of acidic and organic modifiers in the mobile phase and on the column temperature.
M. Ángeles Monge - One of the best experts on this subject based on the ideXlab platform.
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Rhodium(I) complexes with unsymmetric aliphatic diamines. Crystal structure of [Rh(C8H12)(C7N2H16)][RhCl2(C8H12)] and [Rh(C8H12)(C7N2H16)]ClO4
Inorganica Chimica Acta, 1991Co-Authors: Elena Anzuela, María A. Garralda, Ricardo Hernández, Lourdes Ibarlucea, Elena Pinilla, M. Ángeles MongeAbstract:Abstract Reactions of [Rh(COD)Cl]2 with unsymmetric aliphatic diamines (LL′) have been studied. The 1:1 ligand:dimer reactions yield ionic products [Rh(C8H12)(LL′)][RhCl2(C8H12)] that in solution are in equilibrium with the respective binuclear compounds {[RhCl2(C8H12)]2(μ-LL′)}. The X-ray structure of [Rh(C8H12)(C7N2H16)][RhCl2(C8H12)] is presented. When the reactions are performed in media saturated with CO, carbonylated ion-pair complexes are obtained. The 2:1 ligand:dimer reactions afford neutral tetracoordinated [Rh(COD)(LL′)Cl] compounds bonded through the Primary Amino Group, and show rapid interchange of olefinic protons at room temperature. The synthesis and properties of cationic complexes of general formulae [Rh(COD)(LL′)]Cl2 and [Rh(CO)(PPh3)(LL′)]CO4 are also discussed. Cyclooctadiene compounds show association processes in acetone solution, though they are monomeric in the solid state. The X-ray structure of [Rh(C8H12)(C7N2H16)]ClO4 indicates the existence of hydrogen bonding between the oxygens in the perchlorate anion and the Primary Amino Group in the cation.
Jingchao Tao - One of the best experts on this subject based on the ideXlab platform.
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a highly efficient large scale asymmetric michael addition of isobutyraldehyde to maleimides promoted by a novel multifunctional thiourea
ChemInform, 2012Co-Authors: Yuxia Liu, Hang Ren, Yu Zhu, Jingchao TaoAbstract:The new chiral thiourea TUC bearing a chiral lipophilic beyerane scaffold and a Primary Amino Group, catalyzes the asymmetric Michael addition between aliphatic aldehydes and different maleimides (I) with only 0.5 mol % loading.
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A highly efficient large-scale asymmetric Michael addition of isobutyraldehyde to maleimides promoted by a novel multifunctional thiourea
Tetrahedron-asymmetry, 2011Co-Authors: Yuxia Liu, Hang Ren, Yu Zhu, Jingchao TaoAbstract:Abstract A novel class of chiral multifunctional thioureas bearing a chiral lipophilic beyerane scaffold and a Primary Amino Group were designed and prepared. The thioureas were proven to be effective for catalyzing the asymmetric Michael addition between isobutyraldehyde and maleimides with only 0.5 mol % catalyst loading, and exhibited double asymmetric induction. Both of the catalysts afforded the corresponding adduct with high to excellent yields (up to 98%) and excellent enantioselectivities (up to 99%). Furthermore, this catalytic system can be used efficiently in large-scale reactions with the yields and enantioselectivities being maintained at the same level.
Zhiwu Liang - One of the best experts on this subject based on the ideXlab platform.
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Impact of the Inter- and Intramolecular Tertiary Amino Group on the Primary Amino Group in the CO2 Absorption Process
Industrial & Engineering Chemistry Research, 2016Co-Authors: Rui Zhang, Shupanxiang Chen, Qi Yang, Zhiwu LiangAbstract:This work has investigated CO2 absorption using 3-(diethylAmino)propylamine (DEAPA), a diamine that contains one Primary and one tertiary amine in the same molecule. The results are compared with those for the blended amine system of monoethanolamine and methyldiethanolamine (MEA–MDEA), a mixed amine solvent with an equal number of moles of Primary and tertiary amine. The 2 M DEAPA, 2 M MEA, and 4 M MEA–MDEA (1:1 mole ratio) were tested for their CO2 absorption performance. The experimental results show that the intramolecular tertiary Amino Group of DEAPA can promote the CO2 absorption rate of the intramolecular Primary Amino Group and enhance its CO2 absorption capacity. The results using 13C nuclear magnetic resonance also showed that the intermolecular tertiary amine in the MEA–MDEA system was more favored for the promotion of the Primary amine in the blend to form bicarbonate at an earlier CO2 equivalent loading stage and produced less carbamate than the intramolecular tertiary Amino Group of DEAPA d...
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Impact of the Inter- and Intramolecular Tertiary Amino Group on the Primary Amino Group in the CO2 Absorption Process
Industrial & Engineering Chemistry Research, 2016Co-Authors: Rui Zhang, Shupanxiang Chen, Qi Yang, Zhiwu LiangAbstract:This work has investigated CO2 absorption using 3-(diethylAmino)propylamine (DEAPA), a diamine that contains one Primary and one tertiary amine in the same molecule. The results are compared with those for the blended amine system of monoethanolamine and methyldiethanolamine (MEA–MDEA), a mixed amine solvent with an equal number of moles of Primary and tertiary amine. The 2 M DEAPA, 2 M MEA, and 4 M MEA–MDEA (1:1 mole ratio) were tested for their CO2 absorption performance. The experimental results show that the intramolecular tertiary Amino Group of DEAPA can promote the CO2 absorption rate of the intramolecular Primary Amino Group and enhance its CO2 absorption capacity. The results using 13C nuclear magnetic resonance also showed that the intermolecular tertiary amine in the MEA–MDEA system was more favored for the promotion of the Primary amine in the blend to form bicarbonate at an earlier CO2 equivalent loading stage and produced less carbamate than the intramolecular tertiary Amino Group of DEAPA d...