Yasumasa Matsumoto

Mitsubishi Tanabe Pharma Corporation

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Kiyoshi Tomioka

Kyoto University

Ken‐ichi Yamada

Tokushima University

Khalid B. Selim

Mansoura University

Yasutomo Yamamoto

Doshisha Women's College of Liberal Arts

Hirotsugu Nakanishi

Kyoto University

Keiichiro Hanada

Hashimoto Municipal Hospital

Shoji Fukuda

Tokyo Medical University

Akira Sagawa

Nagaoka University of Technology

Shinichi Kusaka

Mitsubishi Tanabe Pharma Corporation

Toshiyuki Kume

Mitsubishi Tanabe Pharma Corporation

Cooperative Institutions

Kyoto University

Kindai University

Hokkaido University

Mitsubishi Tanabe Pharma Corporation

Kyushu University

The University of Tokyo

Osaka University

Tokyo University of Science

Kyoto Pharmaceutical University

Doshisha Women's College of Liberal Arts

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Chiral N-Heterocyclic Carbene−Copper(I)-Catalyzed Asymmetric Allylic Arylation of Aliphatic Allylic Bromides: Steric and Electronic Effects on γ-Selectivity

The Journal of Organic Chemistry (2011)

Khalid B. Selim Hirotsugu Nakanishi Yasumasa Matsumoto Yasutomo Yamamoto Ken‐ichi Yamada

Chiral N-heterocyclic carbene ligands were electronically and sterically tuned to improve γ-selectivity in copper(I)-catalyzed asymmetric allylic arylation of aliphatic allylic bromides with several aryl Grignard reagents. High γ-selectivity was realized when either the aryl group of the Grignard reagent or the aryl group on the N-substituent of the carbene ligand was electron-deficient or when either the carbene ligand or allylic bromide was bulky. The results indicated that electron deficiency and steric hindrance of the initially formed σ-allyl copper intermediate enhance the rate of the reductive elimination to give γ-products as major isomers.

Electronic effect

10.1021/jo102386s

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Citations (61)

Novel Colored Luster Pigments

Journal of the Japan Society of Colour Material (1995)

N. Mronga Volker Radtke Bruno Baumann Yasumasa Matsumoto

Colored

10.4011/shikizai1937.68.411

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Citations (0)

Steric tuning of C2-symmetric chiral N-heterocyclic carbene in gold-catalyzed asymmetric cyclization of 1,6-enynes

Tetrahedron (2012)

Ken‐ichi Yamada Yasumasa Matsumoto Khalid B. Selim Yasutomo Yamamoto Kiyoshi Tomioka

Enyne

10.1016/j.tet.2012.03.107

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Citations (35)

p‐Phenylenediamine Epoxy Resin Film for Redox Enzyme Detection

Macromolecular Symposia (2010)

Ken‐ichi Kan'no Akimitsu Kugimiya Yasumasa Matsumoto Yuya Konishi Tsuyoshi Arakawa

Abstract Summary: Phenylenediamine derivatives (PDs) are environmentally hazardous, though very useful for chemical analysis. To minimize release into the environment, a PD‐containing epoxy resin film was developed that retained redox enzyme activity. p ‐Phenylenediamine and 2,2‐bis(4‐glycidyloxyphenyl)‐propane were cured to produce a violet film. This film was reactive against peroxidase, a redox enzyme that oxidizes phenylenediamine to afford an imine. Enzymatic oxidation caused the film to change color from violet to deep green. The film exhibited fluorescence at 394 nm under excitation at 350 nm, and the fluorescent intensity decreased with greater oxidation. Thus, the film could be used to detect redox enzyme activity.

p-Phenylenediamine

Propane

o-Phenylenediamine

10.1002/masy.200900047

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Modeling and Neutral-Point-Potential Control of Neutral-Point-Clamped PWM Rectifiers using an Optimal Regulator

IEEJ Transactions on Industry Applications (1999)

Shoji Fukuda Yasumasa Matsumoto Akira Sagawa

Neutral-point-clamped voltage source rectifiers (NPCR) are suitable for high voltage systems because of their circuit structure. The NPCRs, however, have a problem that the neutral point potential (NPP) varies when the current flows into or out of the neutral point. The variations cause voltage deviations in the input waveforms as well as unbalanced voltage stress on the devices. Accordingly, reducing NPP variations is very important. This paper describes a controlling method for NPCRs based on a state space model. The neutral point current is treated as one of the inputs. The controller is designed based on the optimal regulator theory in order to achieve the control of DC voltage, power factor and NPP, simultaneously. The validity of the proposed method is demonstrated by experimental results.

10.1541/ieejias.119.109

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Citations (2)

C₂ Symmetric Chiral NHC Ligand for Asymmetric Quaternary Carbon Constructing Copper-Catalyzed Conjugate Addition of Grignard Reagents to 3-Substituted Cyclohexenones

The Journal of Organic Chemistry (2008)

Yasumasa Matsumoto Ken‐ichi Yamada Kiyoshi Tomioka

The asymmetric construction of quaternary carbon centers by conjugate addition of Grignard reagents to 3-methyl- and 3-ethylcyclohexenones was realized in a maximum enantioselectivity of 80% by using a C2 symmetric chiral N-heterocyclic carbene (NHC)-copper catalyst, generated from (4S,5S)-1,3-bis(2-methoxyphenyl)-4,5-diphenyl-4,5-dihydro-1H-imidazol-3-ium tetrafluoroborate and copper(II) triflate. The stereostructures of the NHC-Au complexes were analyzed by X-ray crystallography, which rationalized the good stereocontrolling ability of N-aryl NHCs.

Trifluoromethanesulfonate

Tetrafluoroborate

Conjugate

10.1021/jo800613h

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Citations (130)

ChemInform Abstract: Chiral Carbene Approach to Gold‐Catalyzed Asymmetric Cyclization of 1,6‐Enynes.

ChemInform (2010)

Yasumasa Matsumoto Khalid B. Selim Hirotsugu Nakanishi Ken‐ichi Yamada Yasutomo Yamamoto

Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

10.1002/chin.201016050

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ChemInform Abstract: Steric Tuning of C₂‐Symmetric Chiral N‐Heterocyclic Carbene in Gold‐Catalyzed Asymmetric Cyclization of 1,6‐Enynes.

ChemInform (2012)

Ken‐ichi Yamada Yasumasa Matsumoto Khalid B. Selim Yasutomo Yamamoto Kiyoshi Tomioka

Abstract Eight chiral NHC‐gold(I) complexes are prepared and investigated.

10.1002/chin.201239052

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Efficient Chiral N‐Heterocyclic Carbene/Copper(I)‐Catalyzed Asymmetric Allylic Arylation with Aryl Grignard Reagents

Angewandte Chemie International Edition (2009)

Khalid B. Selim Yasumasa Matsumoto Ken‐ichi Yamada Kiyoshi Tomioka

Gamma rules: The title reaction was achieved in a highly regioselective manner using aryl Grignard reagents with monodentate chiral N-heterocyclic carbene–copper(I) catalyst to give diarylvinylmethanes with excellent enantiomeric excess in excellent yield (see scheme). Detailed facts of importance to specialist readers are published as "Supporting Information". Such documents are peer-reviewed, but not copy-edited or typeset. They are made available as submitted by the authors. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

Phosphoramidite

Enantiomeric excess

10.1002/anie.200904676

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Citations (148)

Efficient Chiral N‐Heterocyclic Carbene/Copper(I)‐Catalyzed Asymmetric Allylic Arylation with Aryl Grignard Reagents

Angewandte Chemie (2009)

Khalid B. Selim Yasumasa Matsumoto Ken‐ichi Yamada Kiyoshi Tomioka

Gamma ist entscheidend: Die Titelreaktion gelang hoch regioselektiv mit Aryl-Grignard-Reagentien und einem Kupfer(I)-Katalysator mit einzähnigem chiralem N-heterocyclischem Carbenliganden und lieferte Diarylvinylmethane mit ausgezeichnetem Enantiomerenüberschuss und in hoher Ausbeute (siehe Schema).

10.1002/ange.200904676

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Citations (41)