The Experts below are selected from a list of 177 Experts worldwide ranked by ideXlab platform
Takashi Sakai - One of the best experts on this subject based on the ideXlab platform.
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the Pentafluorophenyl Group as a module for the direct modification of chiral diamines for asymmetric catalysis
Tetrahedron-asymmetry, 2008Co-Authors: Toshinobu Korenaga, Kenji Nomura, Shinichi Minami, Hitomi Sasaki, Takashi SakaiAbstract:Abstract A Pentafluorophenyl Group embedded in a chiral diamine allows the direct modification of an aryl Group. The diamine is readily converted into para -disubstituted diamines. Although the electronic effect of the modified diamine somewhat lowers the catalytic activity of BINAP–Ru–diamine-catalyzed asymmetric hydrogenation, the enantioselectivity of the product is higher than that obtained by using a typical chiral diamine. Such an easy and direct modification of the chiral ligand has the potential to facilitate the optimization of the steric effect of chiral ligands in asymmetric catalysis.
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effect of conformational control of chiral oxazaborolidine by π π stacking interaction of a Pentafluorophenyl Group toward asymmetric borane reduction
Journal of Fluorine Chemistry, 2007Co-Authors: Toshinobu Korenaga, Koichi Kadowaki, Takashi SakaiAbstract:Abstract A Pentafluorophenyl Group can act as a stereo-controlling Group in oxazaborolidine-catalyzed asymmetric borane reduction through intramolecular π–π stacking interaction with a phenyl Group. The intramolecular π–π interaction in oxazaborolidine bearing Pentafluorophenyl Group is confirmed by calculations and 1 H NMR study. The interaction affects the enantioselectivity of the asymmetric reduction of acetophenone while the extent is small.
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Effect of conformational control of chiral oxazaborolidine by π–π stacking interaction of a Pentafluorophenyl Group toward asymmetric borane reduction
Journal of Fluorine Chemistry, 2007Co-Authors: Toshinobu Korenaga, Koichi Kadowaki, Takashi SakaiAbstract:Abstract A Pentafluorophenyl Group can act as a stereo-controlling Group in oxazaborolidine-catalyzed asymmetric borane reduction through intramolecular π–π stacking interaction with a phenyl Group. The intramolecular π–π interaction in oxazaborolidine bearing Pentafluorophenyl Group is confirmed by calculations and 1 H NMR study. The interaction affects the enantioselectivity of the asymmetric reduction of acetophenone while the extent is small.
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Synthesis of molecular tweezers bearing Pentafluorophenyl and several pendant aryl Groups: Effective application of the modified Suzuki–Miyaura coupling reaction
Journal of Fluorine Chemistry, 2006Co-Authors: Toshinobu Korenaga, Takahiro Kosaki, Yusuke Kawauchi, Takashi SakaiAbstract:Abstract A molecular tweezer bearing two Pentafluorophenyl Groups 2b and its o-methylated aryl homologue 2c were newly synthesized by the slight modification of the known procedure. The low yield in the introduction of Pentafluorophenyl Group to the precursor dibromide 6 was improved by application of the modified Suzuki–Miyaura coupling reaction using C6F5B(OH)2 with Pd2(dba)3/P(t-Bu)3/CsF/Ag2O catalytic system, which was recently developed by us.
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synthesis of a molecular tweezer containing Pentafluorophenyl Groups and investigation of the π π stacking interaction for a Pentafluorophenyl Group in a polar organic solvent
Bulletin of the Chemical Society of Japan, 2005Co-Authors: Toshinobu Korenaga, Takahiro Kosaki, Yusuke Kawauchi, Takashi SakaiAbstract:A molecular tweezer having two bidentate Pentafluorophenyl (C6F5) Groups was synthesized, and the π–π stacking ability of the C6F5 Groups toward benzene derivatives in a polar organic solvent was e...
Toshinobu Korenaga - One of the best experts on this subject based on the ideXlab platform.
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the Pentafluorophenyl Group as a module for the direct modification of chiral diamines for asymmetric catalysis
Tetrahedron-asymmetry, 2008Co-Authors: Toshinobu Korenaga, Kenji Nomura, Shinichi Minami, Hitomi Sasaki, Takashi SakaiAbstract:Abstract A Pentafluorophenyl Group embedded in a chiral diamine allows the direct modification of an aryl Group. The diamine is readily converted into para -disubstituted diamines. Although the electronic effect of the modified diamine somewhat lowers the catalytic activity of BINAP–Ru–diamine-catalyzed asymmetric hydrogenation, the enantioselectivity of the product is higher than that obtained by using a typical chiral diamine. Such an easy and direct modification of the chiral ligand has the potential to facilitate the optimization of the steric effect of chiral ligands in asymmetric catalysis.
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effect of conformational control of chiral oxazaborolidine by π π stacking interaction of a Pentafluorophenyl Group toward asymmetric borane reduction
Journal of Fluorine Chemistry, 2007Co-Authors: Toshinobu Korenaga, Koichi Kadowaki, Takashi SakaiAbstract:Abstract A Pentafluorophenyl Group can act as a stereo-controlling Group in oxazaborolidine-catalyzed asymmetric borane reduction through intramolecular π–π stacking interaction with a phenyl Group. The intramolecular π–π interaction in oxazaborolidine bearing Pentafluorophenyl Group is confirmed by calculations and 1 H NMR study. The interaction affects the enantioselectivity of the asymmetric reduction of acetophenone while the extent is small.
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Effect of conformational control of chiral oxazaborolidine by π–π stacking interaction of a Pentafluorophenyl Group toward asymmetric borane reduction
Journal of Fluorine Chemistry, 2007Co-Authors: Toshinobu Korenaga, Koichi Kadowaki, Takashi SakaiAbstract:Abstract A Pentafluorophenyl Group can act as a stereo-controlling Group in oxazaborolidine-catalyzed asymmetric borane reduction through intramolecular π–π stacking interaction with a phenyl Group. The intramolecular π–π interaction in oxazaborolidine bearing Pentafluorophenyl Group is confirmed by calculations and 1 H NMR study. The interaction affects the enantioselectivity of the asymmetric reduction of acetophenone while the extent is small.
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Synthesis of molecular tweezers bearing Pentafluorophenyl and several pendant aryl Groups: Effective application of the modified Suzuki–Miyaura coupling reaction
Journal of Fluorine Chemistry, 2006Co-Authors: Toshinobu Korenaga, Takahiro Kosaki, Yusuke Kawauchi, Takashi SakaiAbstract:Abstract A molecular tweezer bearing two Pentafluorophenyl Groups 2b and its o-methylated aryl homologue 2c were newly synthesized by the slight modification of the known procedure. The low yield in the introduction of Pentafluorophenyl Group to the precursor dibromide 6 was improved by application of the modified Suzuki–Miyaura coupling reaction using C6F5B(OH)2 with Pd2(dba)3/P(t-Bu)3/CsF/Ag2O catalytic system, which was recently developed by us.
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synthesis of a molecular tweezer containing Pentafluorophenyl Groups and investigation of the π π stacking interaction for a Pentafluorophenyl Group in a polar organic solvent
Bulletin of the Chemical Society of Japan, 2005Co-Authors: Toshinobu Korenaga, Takahiro Kosaki, Yusuke Kawauchi, Takashi SakaiAbstract:A molecular tweezer having two bidentate Pentafluorophenyl (C6F5) Groups was synthesized, and the π–π stacking ability of the C6F5 Groups toward benzene derivatives in a polar organic solvent was e...
Kari Rissanen - One of the best experts on this subject based on the ideXlab platform.
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the Pentafluorophenyl Group as π acceptor for anions a case study
Chemical Science, 2015Co-Authors: Michael Giese, Markus Albrecht, Arto Valkonen, Kari RissanenAbstract:The present study gives a comprehensive insight into anion–π interactions in the solid state, focusing on purely organic and charge-neutral fluorophenyl Groups bearing a positive charge located at a side chain. The detailed statistical analysis of a series of structural data sets shows the geometrical variability of anion–π bonding in the solid state. It reveals the directing substituents at the arene as key elements for the positional preferences of anions above π-systems. The structural variety of the interaction between anions and electron-deficient arenes is considered by use of the hapticity concept. Together with new evaluation criteria, two helpful tools to understand and describe anion–π interactions in the solid are used.
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Di-, tri-, and tetra(Pentafluorophenyl) derivatives for oligotopic anion-π interactions.
Inorganic Chemistry, 2013Co-Authors: Michael Giese, Markus Albrecht, Arto Valkonen, Simon Steike, Anton Ackermann, Kari RissanenAbstract:The present study describes a series of pentafluorobenzyl ammonium salts with two, three, or four C6F5 units in order to investigate simultaneous interactions of several perfluorinated arenes with anions in the crystalline state. Most of the structures show multiple anion−π contacts. However, only 6·2HI reveals an effective encapsulation of the iodide ion by the aromatic units. For comparison, the structure of 4b is investigated because it offers two π-systems with inverse charge distribution to a bromide anion. Only the electron-deficient π-system of the Pentafluorophenyl Group interacts with the anion.
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controlling the position of anions relative to a Pentafluorophenyl Group
New Journal of Chemistry, 2012Co-Authors: Michael Giese, Markus Albrecht, Katharina Wiemer, Arto Valkonen, Kari RissanenAbstract:The position of an anion above an electron-deficient arene can be controlled by the geometry of appended directing Groups. Here a series of ammonium substituted Pentafluorophenyl derivatives is investigated. The presented results are one step on the way to find the ideal structural features for an effective and superior receptor for anion–π studies.
Michael Giese - One of the best experts on this subject based on the ideXlab platform.
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the Pentafluorophenyl Group as π acceptor for anions a case study
Chemical Science, 2015Co-Authors: Michael Giese, Markus Albrecht, Arto Valkonen, Kari RissanenAbstract:The present study gives a comprehensive insight into anion–π interactions in the solid state, focusing on purely organic and charge-neutral fluorophenyl Groups bearing a positive charge located at a side chain. The detailed statistical analysis of a series of structural data sets shows the geometrical variability of anion–π bonding in the solid state. It reveals the directing substituents at the arene as key elements for the positional preferences of anions above π-systems. The structural variety of the interaction between anions and electron-deficient arenes is considered by use of the hapticity concept. Together with new evaluation criteria, two helpful tools to understand and describe anion–π interactions in the solid are used.
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Di-, tri-, and tetra(Pentafluorophenyl) derivatives for oligotopic anion-π interactions.
Inorganic Chemistry, 2013Co-Authors: Michael Giese, Markus Albrecht, Arto Valkonen, Simon Steike, Anton Ackermann, Kari RissanenAbstract:The present study describes a series of pentafluorobenzyl ammonium salts with two, three, or four C6F5 units in order to investigate simultaneous interactions of several perfluorinated arenes with anions in the crystalline state. Most of the structures show multiple anion−π contacts. However, only 6·2HI reveals an effective encapsulation of the iodide ion by the aromatic units. For comparison, the structure of 4b is investigated because it offers two π-systems with inverse charge distribution to a bromide anion. Only the electron-deficient π-system of the Pentafluorophenyl Group interacts with the anion.
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controlling the position of anions relative to a Pentafluorophenyl Group
New Journal of Chemistry, 2012Co-Authors: Michael Giese, Markus Albrecht, Katharina Wiemer, Arto Valkonen, Kari RissanenAbstract:The position of an anion above an electron-deficient arene can be controlled by the geometry of appended directing Groups. Here a series of ammonium substituted Pentafluorophenyl derivatives is investigated. The presented results are one step on the way to find the ideal structural features for an effective and superior receptor for anion–π studies.
Koichi Kadowaki - One of the best experts on this subject based on the ideXlab platform.
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Effect of conformational control of chiral oxazaborolidine by π–π stacking interaction of a Pentafluorophenyl Group toward asymmetric borane reduction
Journal of Fluorine Chemistry, 2007Co-Authors: Toshinobu Korenaga, Koichi Kadowaki, Takashi SakaiAbstract:Abstract A Pentafluorophenyl Group can act as a stereo-controlling Group in oxazaborolidine-catalyzed asymmetric borane reduction through intramolecular π–π stacking interaction with a phenyl Group. The intramolecular π–π interaction in oxazaborolidine bearing Pentafluorophenyl Group is confirmed by calculations and 1 H NMR study. The interaction affects the enantioselectivity of the asymmetric reduction of acetophenone while the extent is small.
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effect of conformational control of chiral oxazaborolidine by π π stacking interaction of a Pentafluorophenyl Group toward asymmetric borane reduction
Journal of Fluorine Chemistry, 2007Co-Authors: Toshinobu Korenaga, Koichi Kadowaki, Takashi SakaiAbstract:Abstract A Pentafluorophenyl Group can act as a stereo-controlling Group in oxazaborolidine-catalyzed asymmetric borane reduction through intramolecular π–π stacking interaction with a phenyl Group. The intramolecular π–π interaction in oxazaborolidine bearing Pentafluorophenyl Group is confirmed by calculations and 1 H NMR study. The interaction affects the enantioselectivity of the asymmetric reduction of acetophenone while the extent is small.
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reestimation of the taft s substituent constant of the Pentafluorophenyl Group
Journal of Organic Chemistry, 2004Co-Authors: Toshinobu Korenaga, Koichi Kadowaki, Takashi SakaiAbstract:The Taft's substituent constant of the Pentafluorophenyl Group (σ*(C6F5)) was reestimated to be 1.50 by correlation between IR spectral data (vCO) and σ* constants for a series of esters (involving the pentafluorobenzyl Group) of 3-phenylpropanoic acid and butanoic acid. The possibility of the disturbance of the correlation by the intramolecular π−π interaction between C6F5 and C6H5 Groups in pentafluorobenzyl 3-phenylpropanoate was excluded by ab initio and DFT calculations of the stable conformations and their carbonyl frequencies. The reestimated σ*(C6F5) value was used for calculation of the pKa value of pentafluorobenzyl alcohol [14.5 (or 14.3)].