KEIO RESEARCHERS INFORMATION SYSTEM

Career 【 Display / hide 】

Career 【 Display / hide 】

• 2005.04

  -

  2008.03

  独立行政法人 日本学術振興会, 特別研究員（DC1）

• 2008.04

  -

  2013.03

  名古屋大学, 工学研究科, 助教

• 2013.04

  -

  2015.04

  名古屋大学, トランスフォーマティブ生命分子研究所, 特任講師

• 2015.05

  -

  2024.03

  名古屋大学, トランスフォーマティブ生命分子研究所, 特任准教授

• 2024.04

  -

  Present

  慶應義塾大学, 理工学部化学科, 教授

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Academic Background 【 Display / hide 】

Academic Background 【 Display / hide 】

• 1999.04

  -

  2003.03

  Kyoto University, 理学部

  University, Graduated

• 2003.04

  -

  2005.03

  Kyoto University, 理学研究科, 化学専攻

  Graduate School, Completed, Master's course

• 2005.04

  -

  2008.03

  Kyoto University, 理学研究科, 化学専攻

  Graduate School, Completed, Doctoral course

Academic Degrees 【 Display / hide 】

Academic Degrees 【 Display / hide 】

• Ph.D.(Sci), Kyoto University, Coursework, 2008.03

Research Areas 【 Display / hide 】

Research Areas 【 Display / hide 】

• Nanotechnology/Materials / Synthetic organic chemistry (分子触媒、光化学、ラジカル、生物活性物質)

Books 【 Display / hide 】

Books 【 Display / hide 】

• 1,2,3-Triazoles and 1,2,3-Triazolium Ions as Catalysts

  Ohmatsu K., Ooi T., Anion Binding Catalysis, 2021.01

  　View Summary

  This chapter deals with the design and applications of 1, 2, 3-triazole-based anion-binding molecular catalysts. Initially, unique properties of 1, 2, 3-triazole derivatives and the leading examples of their exploitation in the field of supramolecular chemistry are described. The distinct ability of chiral oligotriazoles as anion-binding catalysts is highlighted in their use for the asymmetric dearomatization reactions of quinolines, pyridines, and pyryliums, and the differences in catalytic performance between triazole-based catalysts and other chiral anion-binding catalysts are delineated. The latter part of this chapter introduces the design of chiral 1, 2, 3-triazolium ions as anion-binding phase-transfer catalysts and provides an overview of their applications to otherwise difficult-to-achieve asymmetric transformations. The development of multifunctional catalysts featuring 1, 2, 3-triazolium motifs and their synthetic utility are also described.

  • Access to Document (DOI)

• Assembled Ionic Molecular Catalysts and Ligands

  Ohmatsu K., Uraguchi D., Ooi T., Supramolecular Catalysis New Directions and Developments, 2021.01

  　View Summary

  Hydrogen bond and metal–ligand coordinative interaction are widely exploited in asymmetric supramolecular catalysis for the construction of chiral catalytically active supramolecular architectures. Electrostatic interaction between cation and anion can also offer a unique platform for the design of supramolecular catalysts. This chapter describes our approaches toward the development of ionic supramolecular chiral ligands and molecular catalysts.

  • Access to Document (DOI)

Papers 【 Display / hide 】

Papers 【 Display / hide 】

• Deoxygenative [3 + 2] Annulation of α,β-Unsaturated Carbonyl Compounds and Electron-Rich Olefins via Photocatalytic Umpolung of Triarylphosphine

  Ando T., Yokogawa D., Ohmatsu K., Ooi T.

  Journal of the American Chemical Society 147 ( 28 ) 24220 - 24224 2025.07

  Lead author, Last author, Corresponding author, Accepted,  ISSN  00027863

  　View Summary

  A visible-light-driven deoxygenative [3 + 2] annulation between α,β-unsaturated carbonyl compounds and electron-rich olefins was developed, which proceeded under mild conditions with a broad substrate scope and functional group tolerance, enabling straightforward access to diverse substituted cyclopentenes. This cascade annulation strategy exploited the reactivity of phosphine radical cations, generated from triarylphosphines by the oxidation with the excited-state iridium-based photocatalysts, toward olefins to form the corresponding distonic radical cations with a chain length pertinent to constructing cyclopentene scaffolds via sequential radical addition and intramolecular Wittig reaction.

  • Access to Document (DOI)

• Zwitterionic Acridinium Amidate for Photocatalytic Acceptorless Dehydrogenation

  Mori S., Entgelmeier L.M., Kansaku Y., Truong D.A., Mancheño O.G., Ohmatsu K., Ooi T.

  Synlett 36 ( 12 ) 1739 - 1742 2025.07

  Lead author, Last author, Corresponding author, Accepted,  ISSN  09365214

  　View Summary

  The development of catalytic systems that facilitate simple yet valuable molecular transformations in a sustainable manner is of fundamental importance in the field of synthetic organic chemistry. Herein, we report the expedient application of a zwitterionic acridinium amidate, a recently developed direct hydrogen-atom-transfer catalyst, in catalytic acceptorless dehydrogenation (CAD). The combined use of the acridinium amidate with a cobaloxime complex and a protic additive as a catalyst system enables the CAD of hydrocarbons to proceed with high efficiency under mild reaction conditions.

  • Access to Document (DOI)

• Acceptorless Dehydrogenative Aminoalkylation of Allylic C(sp3)-H Bonds via Reversible Hydrogen Atom Transfer

  Minami K., Fujita H., Ohmatsu K., Ooi T.

  Organic Letters 27 ( 26 ) 6919 - 6923 2025.07

  Lead author, Last author, Corresponding author, Accepted,  ISSN  15237060

  　View Summary

  Photoinduced acceptorless dehydrogenative cross-coupling between the benzylic C(sp³)-H bonds of N-benzylanilines and the allylic C(sp³)-H bonds of alkenes was developed through the combined use of an Ir-based photosensitizer, silyl thiol, and 1,2,3-triazolium amidate as catalysts. This protocol exploits the fast and reversible hydrogen atom transfer between α-aminoalkyl radicals and the silyl thiol to facilitate the cross-coupling, directly routing complex aniline derivatives from readily available, less functionalized starting materials under mild conditions.

  • Access to Document (DOI)

• Photocatalytic carbyne reactivity of phosphorus ylides for three-component formal cycloaddition reactions

  Suzuki R., Ando T., Deufel F., Ohmatsu K., Ooi T.

  Nature Synthesis 3 ( 11 ) 1385 - 1391 2024.11

  Lead author, Last author, Corresponding author, Accepted

  　View Summary

  Selective reactions between more than two molecules are governed by appropriate combinations of polar functionalities. This restriction can be ameliorated by photoredox umpolung reactivity, which enables the functionalization of unreactive bonds of chemical reagents while leaving their inherent reactive functional groups intact, paving the way for otherwise difficult multicomponent reactions. Here we report that the photocatalytic single-electron oxidation of phosphorus ylides underpins their sequential assembly with electron-rich olefins and α,β-unsaturated carbonyl compounds to form functionalized six-membered carbocycles. This three-component formal cycloaddition, featuring consecutive C–H functionalization and Wittig reaction of phosphorus ylides, offers a carbyne-like transformation that involves the conversion of inert C–H and C=P bonds into C–C and C=C bonds, respectively, as a powerful tool for the rapid construction of versatile synthetic building blocks from readily available substrates. (Figure presented.)

  • Access to Document (DOI)

• Zwitterionic Acridinium Amidate: A Nitrogen-Centered Radical Catalyst for Photoinduced Direct Hydrogen Atom Transfer

  Entgelmeier L.M., Mori S., Sendo S., Yamaguchi R., Suzuki R., Yanai T., García Mancheño O., Ohmatsu K., Ooi T.

  Angewandte Chemie International Edition 63 ( 43 )  2024.10

  Lead author, Last author, Corresponding author, Accepted,  ISSN  14337851

  　View Summary

  The development of small organic molecules that can convert light energy into chemical energy to directly promote molecular transformation is of fundamental importance in chemical science. Herein, we report a zwitterionic acridinium amidate as a catalyst for the direct functionalization of aliphatic C−H bonds. This organic zwitterion absorbs visible light to generate the corresponding amidyl radical in the form of excited-state triplet diradical with prominent reactivity for hydrogen atom transfer to facilitate C−H alkylation with a high turnover number. The experimental and theoretical investigations revealed that the noncovalent interactions between the anionic amidate nitrogen and a pertinent hydrogen-bond donor, such as hexafluoroisopropanol, are crucial for ensuring the efficient generation of catalytically active species, thereby fully eliciting the distinct reactivity of the acridinium amidate as a photoinduced direct hydrogen atom transfer catalyst.

  • Access to Document (DOI)

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Reviews, Commentaries, etc. 【 Display / hide 】

Reviews, Commentaries, etc. 【 Display / hide 】

• Creating Molecules in the Infinite Space

  Ohmatsu K.

  Yuki Gosei Kagaku Kyokaishi Journal of Synthetic Organic Chemistry 83 ( 10 ) 926 - 929 2025.10

  Lead author, Last author, Corresponding author,  ISSN  00379980

  • Access to Document (DOI)

• Titelbild: Zwitterionic Acridinium Amidate: A Nitrogen‐Centered Radical Catalyst for Photoinduced Direct Hydrogen Atom Transfer (Angew. Chem. 43/2024)

  Angewandte Chemie  2024.10

  Lead author, Last author, Corresponding author

  • Access to Document (DOI)

• Zwitterionic Acridinium Amidate: A Nitrogen‐Centered Radical Catalyst for Photoinduced Direct Hydrogen Atom Transfer

  Angewandte Chemie  2024.10

  Lead author, Last author, Corresponding author

  • Access to Document (DOI)

• Zwitterionic Acridinium Amidate: A Nitrogen‐Centered Radical Catalyst for Photoinduced Direct Hydrogen Atom Transfer

  Angewandte Chemie International Edition  2024.08

  Lead author, Last author, Corresponding author

  • Access to Document (DOI)

• Front Cover: Catalytic Asymmetric Strecker Reaction of Ketoimines with Potassium Cyanide (Asian J. Org. Chem. 12/2021)

  Asian Journal of Organic Chemistry  2021.12

  Lead author, Last author, Corresponding author

  • Access to Document (DOI)

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Research Projects of Competitive Funds, etc. 【 Display / hide 】

Research Projects of Competitive Funds, etc. 【 Display / hide 】

• 水素結合ゲーティング型光触媒の創成

  2026.04

  -

  2028.03

  Research grant, Principal investigator

• ラジカル触媒反応による天然物SReP

  2025.04

  -

  2027.03

  学術変革領域研究(A), Principal investigator

• 光励起窒素ラジカルの触媒機能攻究

  2024.04

  -

  2027.03

  Grants-in-Aid for Scientific Research, Grant-in-Aid for Scientific Research (B), Principal investigator

  　View Summary

  本研究では、物質創製の合理化・効率化に資する合成化学技術の開拓を指向し、多種多様な化合物を原料としたC(sp3)-H結合変換を可能にする新規触媒の創製に挑む。特に、可視光を駆動力として高い反応性を発揮する光励起窒素ラジカルの設計と触媒機能の創出に注力する。分子中に存在する官能基の反応性を足掛かりとして化学反応を実現してきた従来の合成化学と一線を画し、反応性の高い官能基存在下、安定なC(sp3)-H結合の選択的変換を可能にする光励起ラジカル触媒によって、天然物等の複雑分子の効率的合成や直接構造変換を実現する。
  不活性結合の直接変換を可能とする光励起窒素ラジカル触媒の機能探求にもとづき、高難度な分子変換反応の開発を行なった。今年度の研究ではとくに、ラジカル触媒と金属触媒とのハイブリッドシステムとして、双性イオン性アクリジニウムアミデートとコバルト錯体を組み合わせたアルカン類の脱水素反応の開発に注力した。酸化剤を必要としない触媒的脱水素化反応（Catalytic Acceptorless Dehydrogenation, CAD）は、分子状水素(H2)のみを副生成物として発生させつつ、芳香族化合物やオレフィン類を構築する持続可能かつ直接的な方法として注目されているが、反応自体が吸熱的であり、進行には強力な駆動力が必要となる。本研究では、光誘起による直接的水素原子移動（direct Hydrogen Atom Transfer, d-HAT）を担うアクリジニウムアミデート触媒と、水素発生に関与するコバルト錯体を組み合わせることで、温和な条件下で効率的なCAD反応を実現した。具体的には、テトラヒドロナフタレンやインドール、イソキノリン、2-ピリドンといった複素環化合物を含む幅広い基質に対して適用可能であり、選択的かつ高収率で不飽和化合物へと変換することに成功した。また、ベンジルアルコール類の酸化的変換や、複雑なステロイド化合物に対して、特定部位の脱水素化が達成され、その応用可能性の広さを実証した。
  本研究では、光励起窒素ラジカルの機能追究と水素原子移動反応等による不活性結合の直接変換の開拓を目指しており、当初の計画に沿って着実に進展を見せている。今年度においては、独自に開発した双性イオン型アクリジニウムアミデートを用いた光誘起水素原子移動（direct HAT）と、コバルト錯体による水素発生反応を融合させたハイブリッド触媒系を構築し、温和な条件下で多様な基質の脱水素化に成功した。ベンゼン縮環化合物や含窒素複素環に加え、天然物誘導体に対しても高い変換効率と選択性を示し、実用的な有機合成手法としての有望性を明示した。また、触媒作用機構の検証においても、ラジカル種の生成と反応経路に関する知見を得ることができ、触媒設計の指針となる基盤的知識を確立しつつある。これらの成果は、研究目標に対して極めて良好な進捗を与えるものであり、今後さらに多様な結合変換反応の検討を通じて、研究の深化と波及的展開が期待される。
  これまでに得られた成果に基づき、今後は以下の三点を中心に研究のさらなる推進を図る。第一に、基質適用範囲の拡大である。現時点でベンゼン縮環系や含窒素複素環への適用が可能であることを確認しており、今後は脂肪族化合物や複数の官能基を含む医薬品候補化合物への応用を目指す。また、結合活性化の位置選択性制御の高度化やC-H結合以外の不活性結合を標的とした官能基選択的活性化の可能性も検討する。第二に、アクリジニウムアミデート光触媒の構造多様化を通じた触媒性能の最適化である。電子的・立体的特性を精密に調整することで、励起状態のエネルギープロファイルやラジカル生成能を制御し、より選択的かつ効率的な反応設計を可能とする。第三に、反応機構の更なる解明を通じて触媒作用の本質を明らかにし、設計指針の汎用化を図る。特に、時間分解分光法や理論計算を活用し、反応中間体や電子移動過程を詳細に解析する計画である。これらの戦略的方策を通じて、有機分子光触媒を基盤とした持続可能な分子変換技術の確立を目指す。

• オルソゴナル結合変換が拓く新しい合成化学

  2023.04

  -

  2030.03

  国立研究開発法人科学技術振興機構（JST）, 創発的研究支援事業, Research grant, Principal investigator

• Zwitterionic Triazolium Amidate for Previously Difficult Transformations

  2021.04

  -

  2024.03

  Grants-in-Aid for Scientific Research, Ohmatsu Kohsuke, Grant-in-Aid for Scientific Research (B), Research grant, Principal investigator

  　View Summary

  Zwitterionic N-phosphinyl triazolium amides have been developed as a highly active hydrogen atom transfer (HAT) catalyst. This new catalyst allowed for the unique C-H functionalization of the unreactive yet less hindered terminal C-H bonds. By exploiting the features of triazolium amidates, the chemoselective C-H alkylations in the presence of highly reactive polar functional groups have been realized, enabling a new molecular transformation, namely the geminal two-carbon functionalization of benzylic fluorides. Furthermore, the discovery that the conjugate acid of triazolium amidates can realize the proton reduction under the photoredox catalysis led to the development of acceptorless dehydrogenative cross-couplings between two different C-H bonds.
  <BR>
  Translated with DeepL.com (free version)

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Courses Taught 【 Display / hide 】

Courses Taught 【 Display / hide 】

• ORGANIC STRUCTURE AND REACTIONS (BASIC ORGANIC CHEMISTRY 1)

  2026

• LABORATORIES IN CHEMISTRY 2

  2026

• GRADUATE RESEARCH ON CHEMISTRY, LIFE SCIENCE, AND INFORMATICS 2

  2026

• DOCTORAL RESEARCH ON CHEMISTRY, LIFE SCIENCE, AND INFORMATICS

  2026

• MOLECULAR CHEMISTRY AND CHEMICAL BIOLOGY PRACTICAL RESEARCH A

  2026

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