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Takashi Ohshima Last modified date：2023.11.28

Professor / Department of Medicinal Sciences
Department of Chemo-Pharmaceutical Sciences
Faculty of Pharmaceutical Sciences


Graduate School
Department of Medicinal Sciences
Graduate School of Pharmaceutical Sciences
Undergraduate School
Department of General Pharmaceutical Sciences
School of Pharmaceutical Sciences
Other Organization
Other


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Homepage
https://kyushu-u.elsevierpure.com/en/persons/takashi-ohshima
　Reseacher Profiling Tool　Kyushu University Pure
http://www.facebook.com/ohshimatakashi
https://green.phar.kyushu-u.ac.jp/index_e.html
Green Pharmaceutical Chemistry .
Phone
092-642-6650
Academic Degree
Ph. D.
Country of degree conferring institution (Overseas)
No
Field of Specialization
Digitalization-driven Transformative Organic Synthesis, Synthetic Organic Chemistry, Catalysis, Green Sustainable Chemistry, Medicinal Chemistry
ORCID(Open Researcher and Contributor ID)
0000-0001-9817-6984
Total Priod of education and research career in the foreign country
02years00months
Outline Activities
The following topics are currently under investigation in our laboratories:
1. Development of Environmentally Benign Processes Based on the Catalytic Activation of Unreactive Functional Groups
2. Development of New Chemoselective Catalyses
3. Synthesis of Biologically Active Natural Products Using One-Pot Multistep Catalysis
4. Promotion of Drug Discovery Research with the “GreenPharma” Concept
5. Promotion of Digitalization-driven Transformative Organic Synthesis (Digi-TOS)
Research
Research Interests
  • Digitalization-driven Transformative Organic Synthesis (Digi-TOS)
    keyword : Digitalization-driven Organic Synthesis, Artificial Intelligence, Machine Learning, Deep Learning
    2020.06.
  • Peptide drug discovery research for the development of therapeutic agents for infectious diseases
    keyword : unnatural amino acids, COVID-19
    2020.04.
  • New Direct Catalysis for the Synthesis of Unnatural α-Amino Acid Derivatives
    keyword : α-Amino Acid, Catalyst
    2018.06～2021.03.
  • Direct Catalytic α-Functionalization of Carboxylic Acids
    keyword : Carboxylic Acid, Radical, Catalyst
    2018.06～2021.03.
  • Development of Functional Group-targeted Catalysis
    keyword : Catalyst, VChemoselectivity
    2017.04～2019.06.
  • Development of Molecular-targeted Anticancer Drug
    keyword : Anticancer Drug
    2011.03～2013.03.
  • Deacylation of Unactivated Amides to Amines
    keyword : transamidation. ammonium salt, microwave
    2011.03～2013.03.
  • Catalytic Asymmetric Addition of various nucleophiles to N-Unprotected α-Ketiminnoesters
    keyword : catalysis, enantioselective, ketoimine
    2007.04～2021.03.
  • Lewis acid-catalyzed direct substitution of the hydroxy group
    keyword : catalysis, green chemistry, hydroxy group, direct substitution
    2008.04～2011.08.
  • Direct Substitution Reaction of Hydroxyl Group Catalyzed by Platinum Complex
    keyword : catalysis, environmental harmony, platinum, p-allyl complex, allylamines, atom-economy
    2006.04～2013.03.
  • Development of Environmentally Friendly Acylation Reaction using Tetranuclear Zinc Cluster Catalyst
    keyword : catalysis, environmental harmony, transesterification, metal cluster, atom-economy, e-factor
    2005.04～2013.03.
Current and Past Project
  • Synthetic organic chemistry has supported manufacturing by creating highly complex and valuable molecules from readily available organic materials and is now facing major changes due to digitalization. For Japan to continue to lead the world in synthetic organic chemistry, it is urgent to build a foundation for digital organic synthesis (interdisciplinary fusion of experimental and information science) that leads to disruptive innovation in organic synthesis. In this Research Area, we are developing automated methods (molecular design, synthetic pathway search, optimization of reaction conditions, batch-to-flow conversion, and autonomous synthesis systems) that thoroughly utilize artificial intelligence (AI) techniques to eliminate waste and accelerate innovation for creating novel reactions and molecules. We will also construct our own database (DB) optimized for machine learning (ML) in organic chemistry, which will serve as the basis for the development of automated methods.
Academic Activities
Books
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1. Takashi Ohshima, Hiroyuki Morimoto, Tetsuya Kadota, Middle Molecular Strategy (Koichi Fukase, Takayuki Doi (Eds.)) Chapter 16 Development and Integration of New Green Reactions, Springer, 2021.06, Over the last few decades, the quest for environmentally benign chemical transformations has become an important topic in both industrial and academic research. An integrated synthesis that combines multiple reactions in a single operation in one-pot or a flow system without isolating intermediates has recently drawn much attention as a replacement for conventional step-by-step synthesis. Because in the reaction integration process the reaction mixtures are directly used to the next reaction without purification and the generated co- and by-products may have negative effects on the next reaction, integrating highly atom-economical reactions is quite important. To this end, we developed several highly atom-economical direct catalytic reactions. In this review, we focused on the developments of synthesis and reactions of N-unprotected ketimines and their applications for time integration (one-pot sequential process through N-unprotected ketimine synthesis). .
2. Yazaki Ryo, Ohshima Takashi, Cross-Dehydrogenative Coupling of Carbonyls for Heterocycle Synthesis. In Heterocycles via Cross Dehydrogenative Coupling, Srivastava A., Jana C. K. Eds.; pp. 213–229, Springer, Singapore, https://doi.org/10.1007/978-981-13-9144-6_6, 2019.08.
3. Ohshima Takashi, Tetranuclear Zinc Cluster-Catalyzed Transesterification, In New Horizons of Process Chemistry, Tomioka K., Shioiri T., Sajiki H. Eds.; pp. 65-87, Springer, Singapore, ISBN-13: 978-9811034206, 2017.03.
4. Ohshima, T., Comprehensive Chirality (Yamamoto, H. Carreira, E. Eds.)
Chapter 4.18 Catalytic Asymmetric 1,2-Alkynylation. , Elsevier, 2011.04.
Reports
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1. Shibasaki Masakatsu; Ohshima Takashi, Two-center Chiral Phase Transfer Catalysts for Asymmetric Synthesis, Asymmetric Phase Transfer Catalysis; Maruoka, K. Ed.; WILEY-VCH, Weinheim, 2008.03.
2. Shibasaki, Masakatsu; Ohshima, Takashi, Desymmetrizing Heck Reactions, The Heck Reaction; Oestreich, M. Ed.; WILEY-VCH, Weinheim, 2009.03.
Papers
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1. N. Saito, A. Nawachi, Y. Kondo, J. Choi, H. Morimoto, T. Ohshima, Functional Group Evaluation Kit for Digitalization of Information on the Functional Group Compatibility and Chemoselectivity of Organic Reactions, 10.1246/bcsj.20230047, 2023.05.
2. K. Yamada, Y. Kondo, A. Kitamura, T. Kadota, H. Morimoto, T. Ohshima, Organocatalytic Direct Enantioselective Hydrophosphonylation of N-Unsubstituted Ketimines for the Synthesis of α-Aminophosphonates., ACS Catal., 10.1021/acscatal.2c05953, 13, 3158-3163, 2023.02.
3. Tsukushi Tanaka, Yunosuke Koga, Yusaku Honda, Akito Tsuruta, Naoya Matsunaga, Satoru Koyanagi, Shigehiro Ohdo, Ryo Yazaki, Takashi Ohshima, Ternary catalytic α-deuteration of carboxylic acids, Nat. Synth. 2022, 1, 824–830, DOI: 10.1038/s44160-022-00139-9, 824-830, 2022.09, [URL].
4. Yuta Kondo, Yoshinobu Hirazawa, Tetsuya Kadota, Koki Yamada, Kazuhiro Morisaki, Hiroyuki Morimoto, Takashi Ohshima, One-Pot Catalytic Synthesis of α-Tetrasubstituted Amino Acid Derivatives via In Situ Generation of N-Unsubstituted Ketimines, Org. Lett. 2022, 24, 6594–6598, DOI: 10.1021/acs.orglett.2c02587, 2022.09, [URL].
5. Kazumasa Yoshida, Kensuke Nishi, Shuhei Ishikura, Kazuhiko Nakabayashi, Ryo Yazaki, Takashi Ohshima, Masahiko Suenaga, Senji Shirasawa, Toshiyuki Tsunoda, Cancer Spheroid Proliferation Is Suppressed by a Novel Low-toxicity Compound, Pyra-Metho-Carnil, in a Context-independent Manner, Anticancer Res. 2022, 42 (8) 3993–4001, DOI: 10.21873/anticanres.15895, 2022.08, [URL].
6. Tsukasa Shimauchi, Takuro Numaga-Tomita, Yuri Kato, Hiroyuki Morimoto, Kosuke Sakata, Ryosuke Matsukane, Akiyuki Nishimura, Kazuhiro Nishiyama, Atsushi Shibuta, Yutoku Horiuchi, Hitoshi Kurose, Sang Geon Kim, Yasuteru Urano, Takashi Ohshima, Motohiro Nishida, A TRPC3/6 Channel Inhibitor Promotes Arteriogenesis after Hind-Limb Ischemia, Cells 2022, 11, 2041, DOI: 10.3390/cells11132041, 2022.06, [URL].
7. Taro Tsuji, Kayoko Hashiguchi, Mana Yoshida, Tetsu Ikeda, Yunosuke Koga, Yusaku Honda, Tsukushi Tanaka, Suyong Re, Kenji Mizuguchi, Daisuke Takahashi, Ryo Yazaki, Takashi Ohshima, α-Amino acid and peptide synthesis using catalytic cross-dehydrogenative coupling, Nat. Synth. 2022, 1, 304–312, https://doi.org/10.1038/s44160-022-00037-0, 304-312, Press Release from Kyushu University, NIBIO, AMED. Highlighted by Chem-Station, 2022.03, [URL], Ionic or radical α-amino Schiff base methods are well known for the synthesis of α,α-disubstituted α-amino acids. However, the incorporation of sterically demanding groups is challenging with ionic methods, and radical methods require prefunction- alization of the substrates. Now we have developed a dehydrogenative coupling process of α-amino acid Schiff bases with hydrocarbon feedstocks for the synthesis of α,α-disubstituted α-amino acid derivatives. These α-amino acid derivatives were transformed into C- and N-protected amino acids, which could be easily incorporated into peptide synthesis. A range of α-amino acid derivatives could be readily accessed, which includes, notably, those that bear contiguous quaternary cen- tres. Circular dichroism measurements show that the helical peptide structure is stabilized by the highly sterically congested unnatural α-amino acid. Mechanistic studies revealed that deprotonation of the α-amino acid Schiff base is a turnover-limiting step and the use of an enhanced Brønsted basic copper(I) tert-butoxide complex produced a superior catalytic performance. Photoinduction of the catalytic reaction, using blue light-emitting diode radiation, allowed the reaction to proceed without external heating..
8. Tetsu Ikeda, Haruka Ochiishi, Mana Yoshida, Ryo Yazaki, Takashi Ohshima, Catalytic Dehydrogenative β-Alkylation of Amino Acid Schiff Bases with Hydrocarbon, Org. Lett. 2022, 24, 369−373, https://doi.org/10.1021/acs.orglett.1c04042, 2021.12, [URL].
9. Sayuri Hashimoto, Masayoshi Nagai, Kensuke Nishi, Shuhei Ishikura, Kazuhiko Nakabayashi, Ryo Yazaki, Takashi Ohshima, Masahiko Suenaga, Seiji Shirasawa, Toshiyuki Tsunoda, Growth Suppression of Cancer Spheroids With Mutated KRAS by Low-toxicity Compounds from Natural Products, Anticancer Research, 2021, 41, 4061–4070, DOI: https://doi.org/10.21873/anticanres.15207, 2021.08, [URL].
10. Tetsuya Kadota, Masanao Sawa, Yuta Kondo, Hiroyuki Morimoto, Takashi Ohshima*, Catalytic Enantioselective Strecker Reaction of Isatin-Derived N‐Unsubstituted Ketimines, Organic Letters　2021, 23, 4553–4558, DOI: 10.1021/acs.orglett.1c01194, 2021.04, A catalytic enantioselective Strecker reaction of isatin-derived N-unsubstituted ketimines directly afforded the N-unprotected α-aminonitriles with a tetrasubstituted carbon stereocenter in up to 99% ee without requiring protection/deprotection steps. One-pot Strecker reactions from the parent carbonyl compounds were also realized with comparable yields and enantioselectivities. Direct transformations of the N-unprotected α-aminonitrile products streamlined the synthesis of unnatural amino acid derivatives and achieved the shortest one-pot stereoselective routes to a biologically active compound reported to date..
11. Hai-Long Xin, Bo Pang, Jeesoo Choi, Walaa Akkad, Hiroyuki Morimoto, Takashi Ohshima, C–C Bond Cleavage of Unactivated 2-Acylimidazoles, J. Org. Chem. 2020, 85, 11592–11606, 10.1021/acs.joc.0c01458, 2020.08, [URL].
12. Kazuhiro Morisaki, Hiroyuki Morimoto, Takashi Ohshima, Recent Progress on Catalytic Addition Reactions to N-Unsubstituted Imines, ACS Catal. 2020, 10, 6924-6951, 10.1021/acscatal.0c01212, 10, 6924-6951, 2020.05, [URL].
13. Taro Tsuji, Takafumi Tanaka, Tsukushi Tanaka, Ryo Yazaki, Takashi Ohshima, Catalytic Aerobic Cross-Dehydrogenative Coupling of Azlactones en Route to α,α-Disubstituted α-Amino Acids, Org. Lett. 2020, 22, 4164-4170, DOI: 10.1021/acs.orglett.0c01248, 22, 4164-4170, Press Release from Kyushu University, 2020.05, [URL].
14. Yohei Matsumoto, Jun Sawamura, Yumi Murata, Takashi Nishikata, Ryo Yazaki, Takashi Ohshima, Amino Acid Schiff Base Bearing Benzophenone Imine As a Platform for Highly Congested Unnatural α-Amino Acid Synthesis, J. Am. Chem. Soc. 2020, 142, 8498–8505., DOI: 10.1021/jacs.0c02707, 142, 8498-8505, Press Release from Kyushu University, 2020.04, [URL], α-アミノ酸は私たちの体をつくるたんぱく質の構成成分として、生命活動を維持するための重要な役割を担っています。また最近では、創薬分野において低分子と抗体の特徴を有した中分子ペプチド、中でも天然には存在しない非天然—アミノ酸を有する中分子ペプチドが革新的な次世代型医薬品として期待されています。そのため非天然α—アミノ酸の合成法は古くより盛んに研究が行われてきました。しかし立体的に大きな非天然α—アミノ酸、特に連続して立体的に大きな部位をもつ非天然—アミノ酸の合成はこれまで非常に困難で、その機能評価を行うための一般性の高い合成法の開発が強く望まれていました。このような背景のもと、我々は、立体的に大きな非天然α-アミノ酸を効率的に合成する手法の開発に世界に先駆けて成功しました。非天然α-アミノ酸の原料としてO’Donnell教授らによって40年以上前に開発されたアミノ酸Schiff塩基が広く用いられてきましたが、これまでは立体障害に弱いイオン型の反応機構に限定されていました。今回研究グループでは、大きな立体障害を克服するために反応性の高いラジカル型の反応機構に着目し、銅触媒を用いることでアミノ酸Schiff塩基を世界で初めてラジカル型機構で反応させることに成功しました。今回の合成手法を用いることで、様々な種類の立体的に大きな非天然α-アミノ酸合成が可能で、光学活性なα-アミノ酸への展開にも成功しました。本成果により、今後立体的に大きな非天然α-アミノ酸の機能評価や、中分子ペプチド医薬品などの様々な機能性分子創製への応用が期待されます。.
15. Yuta Kondo, Hiroyuki Morimoto, Takashi Ohshima, Recent Progress towards the Use of Benzophenone Imines as an Ammonia Equivalent, Chem. Lett. 2020, 49, 497–504., 10.1246/cl.200099, 49, 497-504, 2020.02, [URL].
16. Tsukushi Tanaka, Ryo Yazaki, Takashi Ohshima, Chemoselective Catalytic α–Oxidation of Carboxylic Acids: Iron/Alkali Metal Cooperative Redox Active Catalysis, J. Am. Chem. Soc. 2020, 142, 4517–4524., DOI: 10.1021/jacs.0c00727, 142, 4517-4524, Press Release from Kyushu University, Highlighted in Synfscts, DOI: 10.1055/s-0040-1707934, 2020.02, [URL], 医薬品等の機能性分子中に数多く見られるエステルやアミドといったカルボニル基の原料として、カルボン酸は入手性・安定性・変換反応の多様性の観点から理想的な構造の一つです。さらに、近年では脱炭酸的アルキル化試薬としての利用も広まりつつあり、より多様な化合物を容易に合成するためにカルボン酸の効率的な修飾法の開発は重要な研究課題です。
カルボン酸のエノラートである1,1-エンジオラートはα-官能基化反応における重要な活性中間体であり、より温和な生成法の開発が望まれていました。しかし、従来法ではカルボン酸特有の酸性のために化学量論量の外部塩基が必要であり、また古典的なイオン型反応を補完しうるレドックス活性な触媒系は未だ達成されていませんでした。このような背景のもと、我々は、化学量論量の外部塩基を必要としない、レドックス活性な金属触媒を用いたラジカル機構によるカルボン酸の触媒的α-酸化反応の開発を行いました。
本研究では詳細な反応機構解析により、鉄とアルカリ金属の異種金属協働型触媒系によるカルボン酸の新規エノラート化機構を明らかにしました。本機構により、本反応ではケトンやエステル、アミドといったカルボニル化合物の共存下におけるカルボン酸の化学選択的なα-酸化反応を達成しました。.
17. Ryohei Yonesaki, Ibuki Kusagawa, Hiroyuki Morimoto, Tamio Hayashi, Takashi Ohshima, Rhodium(I)/Chiral Diene-Catalyzed Enantioselective Addition of Boronic Acids to N-Unsubstituted Isatin-Derived Ketimines, Chem. Asian. J. 2020, 15, 499–502., https://doi.org/10.1002/asia.201901745, 15, 499-502, Highlighted by Chemistry Views, 2020.01, [URL].
18. Yuta Kondo, Tetsuya Kadota, Yoshinobu Hirazawa, Kazuhiro Morisaki, Hiroyuki Morimoto, Takashi Ohshima, Scandium(III) Triflate Catalyzed Direct Synthesis of N-Unprotected Ketimines, Org. Lett. 2020, 22, 120–125, 10.1021/acs.orglett.9b04038, 22, 120-125, Press Release from Kyushu University, 2019.12.
19. Takuya Yokoyama, Masaki Yukuhiro, Yuka Iwasaki, Chika Tanaka, Kazunari Sankoda, Risa Fujiwara, Atsushi Shibuta, Taishi Higashi, Keiichi Motoyama, Hidetoshi Arima, Kazumasa Yoshida, Nozomi Sugimoto, Hiroyuki Morimoto, Hidetaka Kosako, Takashi Ohshima, Masatoshi Fujita, Identification of candidate molecular targets of the novel antineoplastic antimitotic NP-10, Scientific Reports, 2019, 9, 16825-16832, 10.1038/s41598-019-53259-2, 9, 16825, 16832, 2019.11.
20. Ryo Yazaki, Takashi Ohshima, Recent strategic advances for the activation of benzylic C–H bonds for the formation of C–C bonds, Tetrahedron Lett. 2019, 60,151225-151236., DOI:10.1016/j.tetlet.2019.151225, 60, 45, 151225-151236, 2019.11.
21. Hiroyuki Morimoto, Walaa Akkad, Toru Deguchi, Takashi Ohshima, Mechanistic Studies of Nickel(II)-Catalyzed Direct Alcoholysis of 8-Aminoquinoline Amides, Heterocycles, 101, 471–485., DOI: 10.3987/COM-19-S(F)30, 101, 471-485, 2019.10.
22. Ryo Yazaki, Takashi Ohshima, Cross-Dehydrogenative Coupling of Carbonyls for Heterocycle Synthesis, Heterocycles via Cross Dehydrogenative Coupling 2019, 213–229, DOI: 10.1007/978-981-13-9144-6_6, 2019.08.
23. Yuta Kondo, Kazuhiro Morisaki, Yoshinobu Hirazawa, Hiroyuki Morimoto, Takashi Ohshima, A Convenient Preparation Method for Benzophenone Imine Catalyzed by Tetrabutylammonium Fluoride, Org. Process Res. Dev. 2019, 23, 1718–1724, DOI: 10.1021/acs.oprd.9b00226, 23, 1718-1724, 2019.07.
24. Seiya Taninokuchi, Ryo Yazaki, Takashi Ohshima, Mechanistic Insight into Catalytic Aerobic Chemoselective α-Oxidation of Acylpyrazoles, Heterocycles 2019, 99, 906–918, DOI: 10.3987/COM-18-S(F)58, 99, 906-918, 2018.12.
25. Matsumoto Yohei, Taro Tsuji, Nakatake Daiki, Ryo Yazaki, Takashi Ohshima, Thionoesters as 1,2-Dipolarophiles for [4+2] Cycloaddition with Cyclobutanones, Asian J. Org. Chem. 2019, 8, 1071–1074, DOI: 10.1002/ajoc.201900156, 8, 1071-1074, 2019.04.
26. Megumi Noshita, Yuhei Shimizu, Hiroyuki Morimoto, Shuji Akai, Yoshitaka Hamashima, Noriyuki Ohneda, Hiromichi Odajima, Takashi Ohshima, Ammonium Salt-Accelerated Hydrazinolysis of Unactivated Amides: Mechanistic Investigation and Application to a Microwave Flow Process., Org. Process Res. Dev. 2019, 23, 588–594, DOI: 10.1021/acs.oprd.8b00424, 23, 4, 588-594, 2019.03.
27. Masanao Sawa, Shotaro Miyazaki, Ryohei Yonesaki, Hiroyuki Morimoto, Takashi Ohshima, Catalytic Enantioselective Decarboxylative Mannich-Type Reaction of N-Unprotected Isatin-Derived Ketimines, Org. Lett. 2018, 20, 5393–5397, DOI:10.1021/acs.orglett.8b02306, 20, 5393-5397, 2018.08.
28. Ryohei Yonesaki, Yuta Kondo, Walaa Akkad, Masanao Sawa, Kazuhiro Morisaki, Hiroyuki Morimoto, Takashi Ohshima, 3‐Mono‐Substituted BINOL Phosphoric Acids as Effective Organocatalysts in Direct Enantioselective Friedel‐Crafts‐Type Alkylation of N‐Unprotected α‐Ketiminoester, Chem. Eur. J. 2018, 24, 15211–15214, DOI:10.1002/chem.201804078, 24, 15211-15214, 2018.08.
29. Hao Luo, Kensuke Nishii, Shusei Ishikura, Anthony Swain, Naoyuki Morishige Ryo Yazaki, Takashi Ohshima, Senji Shirasawa, Toshiyuki Tsunoda, Growth suppression of human colorectal cancer cells with mutated KRAS by 3-deaza-cytarabine in 3d floating culture, Anticancer research 2018, 38, 4247–4256., DOI: 10.21873/anticanres.12721, 38, 4247-4256, 2018.07.
30. Tsukushi Tanaka, Kayoko Hashiguchi, Takafumi Tanaka, Ryo Yazaki, Takashi Ohshima, Chemoselective Catalytic Dehydrogenative Cross-Coupling of 2-Acylimidazoles: Mechanistic Investigations and Synthetic Scope, ACS Catal. 2018, 8, 8430–8440, DOI:10.1021/acscatal.8b02361, 8, 8430-8440, 2018.07, Chemoselective iron-catalyzed dehydrogenative cross-coupling using 2-acylimidazoles is described. The addition of a phos-phine oxide ligand substantially facilitated the generation of tert-butoxy radicals from di-tert-butyl peroxide, allowing for efficient benzylic C–H bond cleavage under mild conditions. Extensive mechanistic studies revealed that the enolization of 2-acylimidazole proceeded through dual iron catalyst activation, followed by subsequent chemoselective cross-coupling with a benzyl radical over an undesired benzyl radical-derived homo-coupling dimer that inevitably formed in earlier reported con-ditions. A variety of alkylarenes, aliphatic alkane and functionalized 2-acylimidazoles were applicable, demonstrating the synthetic utility of the present catalysis. Contiguous all-carbon quaternary carbons were constructed through dehydrogenative cross-coupling for the first time. The catalytic chemoselective activation of 2-acylimidazole over bidentate coordinative and much more acidic malonate diester was particular noteworthy. Catalytic oxidative cross-enolate coupling of two distinct car-boxylic acid equivalents was also achieved using acetonitrile as a coupling partner..
31. Takafumi Tanaka, Tsukushi Tanaka, Taro Tsuji, Ryo Yazaki, Takashi Ohshima, Strategy for Catalytic Chemoselective Cross-Enolate Coupling Reaction via a Transient Homocoupling Dimer, Org. Lett. 2018, 20, 3541–3544., 10.1021/acs.orglett.8b01313, 20, 3541-3544, 2018.05.
32. Kazuhiro Morisaki, Hiroyuki Morimoto, Mashima, Kazushi, Takashi Ohshima, Development of Direct Enantioselective Alkynylation of α-Ketoester and α-Ketiminoesters Catalyzed by Phenylbis(oxazoline)Rh(III) Complexes, Journal of Synthetic Organic Chemistry, Japan, 2018, 76, 226–240, 10.5059/yukigoseikyokaishi.76.226, 76, 226-240, 2018.03.
33. Matsumoto Yohei, Nakatake Daiki, Ryo Yazaki, Takashi Ohshima, An Expeditious Route to trans-Configured Tetrahydrothiophenes Enabled by Fe(OTf)3-Catalyzed [3+2] Cycloaddition of Donor–Acceptor Cyclopropanes with Thionoesters., Chem. Eur. J. 2018, 24, 6062–6066, 10.1002/chem.201800957, 24, 6062, 6066, 2018.02.
34. Watanabe Kenji, Ohshima Takashi, Bioconjugation with Thiols by Benzylic Substitution, Chem. Eur. J. 2018, 24, 3959–3964, 10.1002/chem.201706149, 24, 3959-3964, 2018.02, タンパク質などの生体由来の分子と合成分子を結びつける手法に生体共役反応があります。医 薬の分野において幅広く用いられており、抗体と薬物の複合体や生命機能を解明するための分子 を合成する上で欠かす事ができません。多くの場合、高い反応性を持つことから、タンパク質中 に含まれるチオール基が生体共役反応の反応点としてよく用いられてきました。しかし、これ までに開発されてきた反応は適用可能な水素イオン濃度指数(pH)に制限があり、pH によっては チオール基の空気酸化、チオールの付加物からのチオール基の脱離が起こるなど問題点がありま した。
今回我々は、これまで生体共役 反応の反応点として用いられてこなかったベンジリック型水酸基に着目しました。ベンジリッ ク型水酸基が適切に配置された反応剤(図)を用いる事で、チオール基の空気酸化が起こらない 弱酸性条件の下で生体共役反応を開発することに成功しました。本反応剤は、中性やアルカリ性 条件ではベンジリック位水酸基が活性化されないため、チオールやアミンと反応せず、弱酸性条件でチオールとのみ特異的に反応しました。反応によって生成したチオールの付加物は、他のチオール類が共存する条件でもチオール基の交換を起こさず、安定に存在しました。さらに、本反応が実際に様々なタンパク質のチオール基の修飾に適用可能であることを見出し、タンパク質への機能性分子の導入にも成功しました。.
35. Das Amrita, Watanabe Kenji, Morimoto Hiroyuki, Ohshima Takashi, Boronic Acid Accelerated Three-Component Reaction for the Synthesis of α-Sulfanyl-Substituted Indole-3-acetic Acids, Org. Lett. 2017, 19, 5794–5797, 10.1002/chem.201703516, 19, 5794-5797, 2017.10.
36. Sawa Masanao, Morisaki Kazuhiro, Kondo Yuta, Morimoto Hiroyuki, Ohshima Takashi, Direct Access to N-Unprotected α- and/or α-Tetrasubstituted Amino Acid Esters via Direct Catalytic Mannich-Type Reactions Using N-Unprotected Trifluoromethyl Ketimines, Chem. Eur. J. 2017, 23, 17022–17028., 10.1002/chem.201703516, 23, 17022-17028, 2017.09, 不斉四置換炭素を持つ非天然アミノ酸類は、天然由来のアミノ酸類とは異なる特性を有し、医薬品や生物活性物質の合成において重要な化合物の1つです。この非天然アミノ酸類の化学合成法の1つとして、ケチミンとカルボニル化合物との反応が世界中で研究されてきました。しかし、これまでの合成法では窒素原子があらかじめ保護されたケチミンを用いており、不要な保護基の着脱が必要となるため合成効率の面で改善の余地を残していました。
　今回、我々は金属触媒を用いることで、窒素原子が無保護のケチミンに対する反応が原子効率100%で円滑に進行し、不斉四置換炭素を持つ様々な窒素上無保護の非天然アミノ酸類を直接合成可能であることを実証しました。また、本反応が有機触媒を用いて不斉合成へと適用可能であることも見出し、種々の不斉四置換炭素を有する非天然アミノ酸類の立体選択的な合成も達成しました。さらに、連続した不斉四置換炭素を有する窒素上無保護の非天然アミノ酸類の立体選択的な直接合成にも世界で初めて成功しました。.
37. Morisaki Kazuhiro, Kondo Yuta, Sawa Masanao, Morimoto Hiroyuki, Ohshima Takashi, Synthesis of 1-Tetrasubstituted 2,2,2-Trifluoroethylamine Derivatives via Palladium-Catalyzed Allylation of sp3 C–H Bonds, Chem. Phar. Bull. 2017, 65, 1089–1092., 10.1248/cpb.c17-00580, 65, 1089-1092, 2017.11.
38. Kazuhiro Morisaki, Hiroyuki Morimoto, Takashi Ohshima, Direct access to N-unprotected tetrasubstituted propargylamines via direct catalytic alkynylation of N-unprotected trifluoromethyl ketimines, Chem. Commun. 2017, 53, 6319–6322., DOI: 10.1039/c7cc02194a, 53, 6319-6322, 2017.04, 医薬品などの原料として有用な化合物にアミン類があります。イミンに対する付加反応は、 種々のアミン類を効率的に合成することができるため、世界中で研究が行われてきました。しか し、これまで開発された反応は、反応性・選択性の制御や生成物の安定性の面から窒素原子があ らかじめ保護されたイミン (N-protected imines) を用いるのが常識でした。そのため、合成素子として有用な無保護のアミン類を得るためには不要な保護基を取り除く必要があり、合成工程数 や環境調和性の面で改善の余地を残していました。
今回我々は、 これまであまり用いられてこなかった窒素原子が保護されていないイミン (N-unprotected imines) を用いることで、保護基を不要とする新しい無保護アミン類の合成手法を確立すること に成功しました。大嶋教授・森本講師らは、窒素原子が保護されていないイミンが末端アルキン*2 の付加反応に利用可能であることを見出し、容易に入手可能な亜鉛試薬とカルボン酸を組み合わ せた新たな触媒によって、種々の無保護アミン類を直接的かつ効率的に合成することに成功しま した(下図)。また、得られた無保護アミン類が生物活性物質の誘導体へと直接変換可能であるこ とも実証しました。.
39. Seiya Taninokuchi, Ryo Yazaki, Takashi Ohshima, Chemoselective α-Oxidation of Acylpyrazoles en Route to α-Hydroxy Acid Derivatives, Org. Lett., 2017, 19, 3187–3190, DOI: 10.1021/acs.orglett.7b01293, 19, 12, 3187-3190, 2017.03.
40. Toru Deguchi, Hai-Long Xin, Hiroyuki Morimoto, Takashi Ohshima, Direct Catalytic Alcoholysis of Unactivated 8-Aminoquinoline Amides, ACS Catal. 2017, 7, 3157–3161., DOI: 10.1021/acscatal.7b00442, 7, 3157-3161, 2017.03, アミドはタンパク質や高分子、生理活性物質などに広くみられる重要な構造の１つです。近年は有機化合物の炭素—水素結合官能基化反応における合成中間体としても注目されていますが、活性化されていないアミド結合の切断はその安定性の高さから一般に困難であり、強酸や強塩基などの厳しい条件が必要なため、官能基共存性に改善の余地を残していました。また、近年アルコールを用いる触媒的切断手法も開発されていましたが、アミド型配向基を直接切断可能な反応は報告がありませんでした。今回我々は、アミド型配向基として数多く利用されている8-アミノキノリンアミドについてアルコールによる切断反応の検討を行った結果、入手容易で水や空気に安定なニッケル触媒が有効に機能することを見出し、対応するエステルへの変換を達成しました。本反応は、炭素—水素結合官能基化反応の生成物に対しても有効に機能し、グラムスケール合成への適用や配向基の回収も可能でした。また、既存の切断反応では実現困難な高い官能基共存性や化学選択性も実現しており、同分野で開発した鉄(III)サレン触媒を用いることでアルコールの適用基質の拡大にも成功していることから、多様な構造を有するエステルの合成への応用も期待されます。.
41. Kazuhiro Morisaki, Hiroyuki Morimoto, Kazushi Mashima, Takashi Ohshima, DIRECT ENANTIOSELECTIVE ALKYNYLATION OF α-KETOESTERS AND α-KETIMINOESTERS CATALYZED BY [BIS(OXAZOLINE)PHENYL] RHODIUM(III) COMPLEXES, Heterocycles 2017, 95, 637–661., DOI: 10.3987/REV-16-SR(S)4, 95, 637-661, 2017.01.
42. Renshi Li, Tomoki Takeda, Takashi Ohshima, Hideyuki Yamada, Yuji Ishii, Metabolomic profiling of brain tissues of mice chronically exposed to heroin, Drug Metab. Pharmacokinet. 2017, 32, 108–111, DOI: 10.1016/j.dmpk.2016.10.410, 32, 108-111, 2017.02.
43. Zhao Li, Masamichi Tamura, Ryo Yazaki, Takashi Ohshima, Catalytic Chemoselective Conjugate Addition of Amino Alcohols to α,β-Unsaturated Ester: Hydroxy Group over Amino Group and Conjugate Addition over Transesterification., Chem. Pharm. Bull. 2017, 65, 19–21, DOI: 10.1248/cpb.c16-00333, 65, 19-21, 2017.01.
44. Megumi Noshita, Yuhei Shimizu, Hiroyuki Morimoto, Takashi Ohshima, Diethylenetriamine-Mediated Direct Cleavage of Unactivated Carbamates and Ureas, Org. Lett. 2016, 18, 6062–6065, DOI: 10.1021/acs.orglett.6b03016, 2016.11.
45. Yumi Yamamoto, Jun Arai, Takuya Hisa, Yohei Saito, Takahiro Mukai, Takashi Ohshima, Minoru Maeda, Isomeric iodinated analogs of nimesulide: synthesis, physicochemical characterization, cyclooxygenase-2 inhibitory activity, and transport across Caco-2 cells, Bioorg. Med. Chem. 2016, 24, 3727–3733., DOI: org/10.1016/j.bmc.2016.06.015, 2016.06.
46. Daiki Nakatake, Ryo Yazaki, Takashi Ohshima, Chemoselective Transesterification of Acrylate Derivatives for Functionalized Monomer Synthesis Using a Hard Zinc Alkoxide Generation Strategy, Eur. J. Org. Chem. 2016, 10.1002/ejoc.201600737, 2016.07.
47. Zhao Li, Ryo Yazaki, Takashi Ohshima, Chemo- and Regioselective Direct Functional Group Installation through Catalytic Hydroxy Group Selective Conjugate Addition of Amino Alcohols to α,β-Unsaturated Sulfonyl Compounds, Org. Lett. 2016, 10.1021/acs.orglett.6b01464, 2016.06.
48. Rikiya Horikawa, Chika Fujimoto, Ryo Yazaki, Takashi Ohshima, μ-Oxo-Dinuclear Iron(III) Catalyzed O-Selective Acylation of Aliphatic and Aromatic Amino Alcohols and Transesterification of tert-Alcohols, Chem. Eur. J. 2016, 10.1002/chem.201602801, 2016.06, 我々は、従来の触媒では達成困難であったエステル合成を可能とする高活性鉄触媒の開発に成功しました。　エステルは医薬品などの様々な機能成分子が含まれるためその合成法の研究が盛んに行われてきました。近年ではグリーンケミストリーの観点から「触媒」を用いたエステル合成法が多く研究されています。しかし用いることのできる原料に制限があり、特に立体障害の大きなエステルの触媒的合成法の開発が強く望まれていました。今回本研究グループでは、これまで困難であった原料を用いたエステル合成を可能とする高活性鉄触媒の開発に成功しました。例えば、安価なメチルエステルから合成化学上有用なtert-ブチルエステルを合成することが可能であり、これは世界で初めての成功例です。tert-ブチルエステルはアミノ酸のペプチド合成やポリエステルなどの高分子材料の合成で非常に重要です。また私たち独自の化学選択的な反応においても、より精密な制御が要求される活性エステルを原料として用いることが可能で、様々な医薬品を原料として用いることもでき、芳香族アミノアルコールの水酸基選択的アシル化も世界初となります。.
49. Kazuhiro Morisaki, Masanao Sawa, Ryohei Yonesaki, Hiroyuki Morimoto, Kazushi Mashima, Takashi Ohshima, Mechanistic Studies and Expansion of the Substrate Scope of Direct Enantioselective Alkynylation of α-Ketiminoesters Catalyzed by Adaptable (Phebox)Rh(III) Complexes, J. Am. Chem. Soc. 2016, DOI: 10.1021/jacs.6b01590, 2016.06, 今回我々は、α位二置換非天然アミノ酸誘導体の不斉合成に有効な末端アルキンの触媒的付加反応の反応機構解析および適応範囲の拡大に成功しました。　α位二置換非天然アミノ酸は、生体内での生物学的安定性の観点などからペプチド医薬品の原料としての利用が期待されています。我々は以前の研究で、環境調和性に優れたα位二置換非天然アミノ酸合成に有効である、ロジウム触媒による末端アルキンの直接的付加反応を見出していました。本反応の詳細な反応機構解析の結果、より高活性な新規触媒を見いだし、反応性の向上・触媒量の低減化・適応範囲の拡大に成功しました。これにより、種々のα位二置換非天然アミノ酸誘導体の効率的合成が可能となりました。.
50. Daiki Nakatake, Ryo Yazaki, Yoshimasa Matsushima, Takashi Ohshima, Transesterification Reaction Catalyzed by Recyclable Heterogeneous Zinc/Imidazole Catalyst, Adv. Synth. Catal. 2016, 10.1002/adsc.201600229, 2016.06.
51. Kazushi Agura, Yukiko Hayashi, Mari Wada, Daiki Nakatake, Kazushi Mashima, Takashi Ohshima, Studies of the Electronic Effects of Zinc Cluster Catalysts and their Application to the Transesterification of β-Keto Esters, Chem. Asian J. 2016, 10.1002/asia.201600062, 2016.04.
52. Keisuke Tokumasu, Ryo Yazaki, Takashi Ohshima, Direct Catalytic Chemoselective α-Amination of Acylpyrazoles: A Concise Route to Unnatural α-Amino Acid Derivatives, J. Am. Chem. Soc., 2016, 138, 2664–2669. , 10.1021/jacs.5b11773, 2016.02.
53. Daiki Nakatake, Yuki Yokote, Yoshimasa Matsushima, Ryo Yazaki, Takashi Ohshima, A highly stable but highly reactive zinc catalyst for transesterification supported by a bis(imidazole) ligand, Green Chem., 2016, Advance Article, DOI: 10.1039/C5GC02056E , 10.1039/C5GC02056E, 2015.10.
54. Ming Zhang, Kenji Watanabe, Masafumi Tsukamoto, Ryozo Shibuya, Hiroyuki Morimoto, Takashi Ohshima, A Short Scalable Route to (−)-α-Kainic Acid Using Pt-Catalyzed Direct Allylic Amination, Chemistry - A European Journal, DOI: 10.1002/chem.201406557, Volume 21, Issue 10, pages, 3937-3941, 2015.03, An increased supply of scarce or inaccessible natural products is essential for the development of more sophisticated pharmaceutical agents and biological tools, and thus the development of atom-economical, step-economical and scalable processes to access these natural products is in high demand. Herein we report the development of a short, scalable total synthesis of (−)-α-kainic acid, a useful compound in neuropharmacology that is, however, limited in supply from natural resources. The synthesis features sequential platinum-catalyzed direct allylic aminations and thermal ene-cyclization, enabling the gram-scale synthesis of (−)-α-kainic acid in six steps and 34 % overall yield..
55. Yuhei Shimizu, Megumi Noshita, Yuri Mukai, Hiroyuki Morimoto, Takashi Ohshima, Cleavage of unactivated amide bonds by ammonium salt-accelerated hydrazinolysis (Backcover), Chem. Commun. , DOI: 10.1039/C4CC02014F , 50, 12623-12625, 2014.05.
56. Ryozo Shibuya, Lu Lin, Yasuhito Nakahara, Kazushi Mashima, Takashi Ohshima, Dual Platinum and Pyrrolidine Catalysis in the Direct Alkylation of Allylic Alcohols: Selective Synthesis of Monoallylation Products, Angew. Chem. Int. Ed., 10.1002/anie.201311200, 53, 4377–4381, 2014.04, A dual platinum- and pyrrolidine-catalyzed direct allylic alkylation of allylic alcohols with various active methylene compounds to produce products with high monoallylation selectivity was developed. The use of pyrrolidine and acetic acid was essential, not only for preventing undesirable side reactions, but also for obtaining high monoallylation selectivity.(Article first published online: 6 MAR 2014).
57. Hiroyuki Morimoto, Risa Fujiwara, Yuhei Shimizu, Kazuhiro Morisaki, Takashi Ohshima, Lanthanum(III) Triflate Catalyzed Direct Amidation of Esters, Org. Lett., 10.1021/ol500593v, 16, 2018–2021., 2014.03.
58. Shuhei　Uesugi, Zhao Li, Ryo Yazaki, Takashi Ohshima, Chemoselective Catalytic Conjugate Addition of Alcohols over Amines., Angew. Chem. Int. Ed., 10.1002/anie.201309755, 53, 1611–1615., 2014.02, A highly chemoselective conjugate addition of alcohols in the presence of amines is described. The cooperative nature of the catalyst enabled chemoselective activation of alcohols over amines, allowing the conjugate addition to soft Lewis basic α,β-unsaturated nitriles. Divergent transformation of the nitrile functionality highlights the utility of the present catalysis.（Article first published online: 22 JAN 2014）.
59. Kazuhiro Morisaki, Masanao Sawa, Jun-ya Nomaguchi, Hiroyuki Morimoto, Yosuke Takeuchi, Kazushi Mashima, Takashi Ohshima, Rh-Catalyzed Direct Enantioselective Alkynylation of α-Ketiminoesters, Chem. Eur. J. , 19,(26), 8417-8420, 2013.06, A green way to amino acids: α-Tetrasubstituted α-amino acid derivatives are formed in high yield and enantioselectivity by using a Rh-catalyzed enantioselective alkynylation of α-ketiminoesters. This reaction, which involves a proton transfer and can be conducted at room temperature, has high substrate scope (see scheme; Cbz=benzyloxycarbonyl, Fmoc=9-fluorenylmethyloxycarbonyl)..
60. Yukiko Hayashi,, Stefano Santoro, Yuki Azuma, Fahmi Himo, Takashi Ohshima, Kazushi Mashima, Enzyme-like Catalysis via Ternary-Complex Mechanism: Alkoxy-bridged Dinuclear Cobalt Complex Mediates Chemoselective O-Esterification over N-Amidation, J. Am. Chem. Soc., 10.1021/ja400367h, 135, 16, 6192-6199, 2013.03.
61. Takashi Ohshima, Kazushi Mashima, Platinum-Catalyzed Direct Amination of Allylic Alcohols, Journal of Synthetic Organic Chemistry, Japan , 10.1002/anie.201202354, 70, 1145-1156, 2012.07.
62. Takashi Ohshima, Junji Ipposhi, Yasuhito Nakahara, Ryozo Shibuya, Kazushi Mashima, Aluminum Triflate as a Powerful Catalyst for Direct Amination of Alcohols, Including Electron-Withdrawing Group-Substituted Benzhydrols, Adv. Synth. Catal., 10.1002/adsc.201200536, 354, 2447-2452, 2012.08.
63. Yuhei Shimizu, Hiroyuki Morimoto, Ming Zhang, Takashi Ohshima, Microwave-Assisted Deacylation of Unactivated Amides to Amines Using Ammonium Salt-Accelerated Transamidation, Angew. Chem. Int. Ed, 10.1002/anie.201202354, 51, 8564-8567, 2012.07, Deacylation of unactivated amides to give amines is a fundamental reaction in organic chemistry, but classical hydrolysis of amides generally requires harsh reaction conditions, i.e., strong acids or bases at high temperature, because amide bonds are chemically robust due to delocalization of the electrons in amides. Although a number of reports have been published to overcome the problems, these methods have limitations such as the use of moisture-sensitive reagents and substrate specificity. Therefore, there is need for developing a practical and efficient method to promote deacylation of unactivated amides to produce amines under mild conditions.

Transamidation is another method to cleave amide bonds to give amines, which could be performed under milder conditions than hydrolysis because amine is more nucleophilic than water. However, reported transamidations were mostly limited to the reactions of primary amides to give secondary or tertiary amides or an intramolecular variant with the release of ring strains, both of which could not be applied for deacylation of amines. Although Gellman and Stahl reported aluminum or zirconium amide-catalyzed intermolecular transamidations of secondary and tertiary amides, these catalytic methods suffer from producing equilibrium mixtures of starting and targeting materials as well as sensitivity to acidic functionalities. Thus, practical application of transamidation for the deacylation of unactivated amides to amines requires further development.

In this paper, we describe microwave-assisted deacylation of unactivated amides to amines using ammonium salt-accelerated transamidation. The reactions proceed under mild conditions (as low as 50°C) with simple and readily available ammonium salts and ethylenediamine as reagents without special care regarding air and moisture. This method is applicable to a variety of acylated amines and compatible with a wide range of functional groups, including unprotected carboxylic acid, phenol, and indole, as well as acid-labile MOM, MEM, and THP groups, and a base-labile TIPS group. Such acylated amines are well utilized in asymmetric hydrogenation of enamides and kinetic resolution as well as C–H activation reactions in recent years.
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64. Takashi Ohshima, Yukiko Hayashi,, Kazushi Agura, Yuka Fujii, Asako Yoshiyama, Kazushi Mashima, Sodium methoxide: a simple but highly efficient catalyst for the direct amidation of esters, Chem. Commun., 10.1039/c2cc32153j, 48, 5434-5436, 2012.04, A simple NaOMe catalyst provides superior accessibility to a wide variety of functionalized amides including peptides through direct amination of esters in an atom-economical and environmentally benign way..
65. Das, Kalpataru; Shibuya, Ryozo; Nakahara, Yasuhito; Germain, Nicolas; Ohshima, Takashi; Mashima, Kazushi, Platinum-Catalyzed Direct Amination of Allylic Alcohols with Aqueous Ammonia for Selective Synthesis of Primary Allylamines., Angew. Chem. Int. Ed., 10.1002/anie.201106737, 51, 150-154, 2011.11, Direct amination of unactivated allylic alcohols with aqueous ammonia was catalyzed by Pt–DPEphos complex to give the corresponding allylamines along with water as a sole co-product. Under optimized conditions, primary allylamines were obtained as major products with excellent monoallylation selectivity (90:10 ~ >99:1). Aqueous conditions were essential for achieving primary allylamines in high yield..
66. Takashi Ohshima, Direct substitution of the hydroxy group with highly functionalized nitrogen nucleophiles catalyzed by Au(III)., Chem. Commun., 10.1039/c1cc12760h, 47, 8322-8234, 2011.06, A direct catalytic substitution of various allylic and benzylic alcohols with synthetically useful, but acid-sensitive Boc, Bus, and Dios protected amine nucleophiles, which have not been well utilized for Lewis acid catalysis, with various functionalities (OTBS, OTHP, etc.) were efficiently catalyzed by 1 mol% of Au(III) under mild conditions..
67. T. Ohshima, T. Kawabata, Y. Takeuchi, T. Kakinuma, T. Iwasaki, T. Yonezawa, H. Murakami, H. Nishiyama, K. Mashima, C1-Symmetric Rh-Phebox-Catalyzed Asymmetric Alkynylation of α-Keto Ester, Angew. Chem. Int. Ed., 10.1002/anie.201100252, accepted, 2011.05, Bifunctional Acid/Base Rh Catalyst: A newly developed C1-symmetric Rh-Phebox complex efficiently catalyzed an asymmetric alkynylation of α-keto ester with various aryl and alkyl substituted terminal alkynes to provide the corresponding chiral tertiary propargylic alcohols with up to 99% ee..
68. T. Ohshima, T. Iwasaki, Y. Maegawa, A. Yoshiyama, K. Mashima, Enzyme-like Chemoselective Acylation of Alcohols in the presence of Amines Catalyzed by a Tetranuclear Zinc Cluster, J. Am. Chem. Soc., 10.1021/ja711349r, 130, 2945-2946, 130, 2944-2945 (2008), 2008.03.
Presentations
 Show All Presentations >>
1. Takashi Ohshima, Controlling and Digitization of Chemoselectivity by Functional Group Targeted Catalyst and by Functional Group Evaluation Kit, 11th Singapore International Chemistry Conference (SICC-11), 2022.12.
2. Takashi Ohshima, Preparation and Reactions of N-Unprotected Ketimines (Invited Lecture), Pacifichem 2021, 2021.12.
3. Takashi Ohshima, Catalytic radical cross-coupling reaction for the synthesis of highly congested unnatural α-amino acids (Invited Lecture), Pacifichem 2021, 2021.12.
4. Takashi Ohshima, Recent Progress on Catalytic Synthesis of Unnatural α-Amino Acid Derivatives (Invited Lecture), Asian Core Program Lectureship (Southern University, Shenzhen, Dec.4), 2019.12.
5. Takashi Ohshima, Recent Progress on Catalytic Synthesis of Unnatural α-Amino Acid Derivatives (Invited Lecture), Asian Core Program Lectureship (Peking University, Shenzhen, Dec.5), 2019.12.
6. Takashi Ohshima, Integration of Environmentally Friendly Direct Transformations (Invited Lecture), The 18th Asian Chemical Congress (ACC), 2019.12.
7. Takashi Ohshima, Yuta Kondo, Kazuhiro Morisaki, Tetsuya Kadota, Yoshinobu Hirazawa, Hiroyuki Morimoto, New Catalytic Synthetic Methods of N-Unprotected Ketimines (Poster), Tateshina Conference 2019, 2019.11.
8. Takashi Ohshima, One-Pot Process Based on Sc-Catalyzed Direct N-Unprotected Ketimine Synthesis (Poster), International Joint Symposium on Synthetic Organic Chemistry, 2019.11.
9. Takashi Ohshima, Recent Progress on the Synthesis of Unnatural α-Amino Acid Derivatives (Invited Lecture), National Taiwan Normal University Department Seminar, 2019.11.
10. Takashi Ohshima, N-Unprotected Ketimines (Invited Lecture), The 14th International Conference on Cutting-Edge Organic Chemistry in Asia (ICCEOCA-14), 2019.09, Ketimines are highly useful compounds for the synthesis of various pharmaceuticals and biologically active amines and amino acids. For example, enantioselective nucleophilic addition to ketimines is one of the most straightforward approaches to synthesize optically active tetrasubstituted amines. Recently, several direct catalytic additions to N-protected ketimines were reported including our Rh-catalyzed enantioselective alkynylation.1 To obtain N-unprotected amines, however, they require additional deprotection steps, which limit their synthetic utilities. Although a prominent way to address these issues is using N-unprotected ketimines, there is only limited success using N-unprotected ketimines as an electrophile.
In this presentation, I disclose the direct catalytic asymmetric addition of various nucleophiles to N-unprotected ketimines. By proper choice of catalysts, alkynylation, Mannich-type reaction, Friedel-Crafts-type reaction, and decarboxylative Mannich-type reaction proceeded smoothly to afford the corresponding N-unprotected tetrasubstituted amines, including highly sterically congested α- and β-tetrasubstituted amino acid esters, in high yield with high enantio- and diastereoselectivity. In addition, we also succeeded in the development of new catalytic methods for synthesizing N-unprotected ketimines. Application to the one-pot synthesis of valuable compounds via N-unprotected ketimines is also demonstrated..
11. Takashi Ohshima, Catalytic α-Amination of Acylpyrazoles and Catalytic Addition of Various Nucleophile to N-Unprotected Ketimines for the Synthesis of Unnatural α-Amino Acid Derivatives (Invited Lecture), University of Strasbourg Department Seminar, 2019.07.
12. Takashi Ohshima, Development of Direct Catalysis for the Synthesis of Unnatural α-Amino Acid Derivatives (Invited Lecture), the 2019 National Taiwan Normal University (NTNU)-Kyushu University Joint Forum on Facilitating Interdisciplinary Research and Education, 2019.05.
13. Takashi Ohshima, Takafumi Tanaka, Tsukushi Tanaka, Taro Tsuji, Ryo Yazaki, Catalytic Chemoselective Cross-Enolate Coupling Reaction via a Transient Homo-Coupling Dimer (Poster), The 13th International Conference on Cutting-Edge Organic Chemistry in Asia (ICCEOCA-13), 2018.11.
14. Takashi Ohshima, Catalytic Chemoselective Cross-Enolate Coupling Reaction via a Transient Homo-Coupling Dimer (Poster), Tateshina Conference on Organic Chemistry, 2018.11.
15. Takashi Ohshima, Catalytic Chemoselective Cross-Enolate Coupling Reaction via a Transient Homo-Coupling Dimer (Invited Lecture), The 13th International Symposium on Organic Reactions (ISOR-13), 2018.11.
16. Takashi Ohshima, Construction of Tetrasubstituted Carbon Stereocenters via Catalytic Nucleophilic Additions to N-Unprotected Ketimines (Invited Lecture), 6th Japan–UK Symposium on Asymmetric Catalysis, 2018.11.
17. Takashi Ohshima, Takafumi Tanaka, Tsukushi Tanaka, Taro Tsuji, Ryo Yazaki , Catalytic Chemoselective Cross-Enolate Coupling Reaction (Poster), The 4th International Symposium on Middle Molecular Strategy (ISMMS-4), 2018.11.
18. Takashi Ohshima, Development of Direct Catalysis without Using Protecting or Activating Group (Invited Lecture), Asian Core Program Lectureship (Taiwan), 2018.08.
19. Takashi Ohshima, Development of Direct Catalysis without Using Protecting or Activating Group (Invited Lecture), Asian Core Program Lectureship (Taiwan), 2018.08.
20. Takashi Ohshima, Development of Direct Catalysis without Using Protecting or Activating Group (Invited Lecture), Asian Core Program Lectureship (Taiwan), 2018.08.
21. Takashi Ohshima, Catalytic Addition of Various Nucleophile to N-Unprotected Ketimines for the Synthesis of Unnatural N-Amino Acid Derivatives (Invited Lecture), Seoul National University Department Seminar, 2018.08.
22. Takashi Ohshima, Catalytic Addition of Various Nucleophile to N-Unprotected Ketimines for the Synthesis of Unnatural N-Amino Acid Derivatives(Invited Lecture), The 1st Scripps Korea Society Symposium, 2018.08.
23. Takashi Ohshima, Das Amrita, Takumi Kimijima, Kenji Watanabe, Development of Mild and Selective Oxidative Heck Reaction to Derivatize Complex Molecules and Reactivity Study of Heteroarenes(Poster), 28th International Conference on Organometallic Chemistry (ICOMC-2018), 2018.07.
24. Takashi Ohshima, Development of Direct Catalysis without Using Protecting or Activating Group (Invited Lecture), Heidelberg University Department Seminar, 2018.07.
25. Takashi Ohshima, Direct Catalytic Asymmetric Addition of Various Nucleophiles to N-Unprotected Ketimines (Award Lecture), International Congress on Pure & Applied Chemistry (ICPAC) 2018, 2018.03.
26. Takashi Ohshima, Catalytic α-Amination of Acylpyrazoles and Catalytic Addition of Various Nucleophile to N-Unprotected α-Ketimins for the Synthesis of Unnatural α-Amino Acid Derivatives (Invited Lecture), Asian Core Program Lectureship (Singapore), 2018.01.
27. Takashi Ohshima, Catalytic α-Amination of Acylpyrazoles and Catalytic Addition of Various Nucleophile to N-Unprotected α-Ketimins for the Synthesis of Unnatural α-Amino Acid Derivatives (Invited Lecture), Asian Core Program Lectureship (Singapore), 2018.01.
28. Takashi Ohshima, Direct Catalytic Asymmetric Addition of Various Nucleophiles to N-Unprotected Ketimines (Invited Lecture), IRCCS-JST CREST Joint Symposium (IMCE), 2018.01.
29. Takashi Ohshima, μ-Oxo-Dinuclear Iron(III) Catalyzed O-Selective Acylation of Aliphatic and Aromatic Amino Alcohols and Transesterification of tert-Alcohols(Poster Presentation), The 12th International Conference on Cutting-Edge Organic Chemistry in Asia (ICCEOCA-12)/The 3rde Advanced Research Network on Cutting-Edge Organic Chemistry in Asia (ARNCEOCA-3), 2017.11.
30. Takashi Ohshima, Direct Catalytic Asymmetric Addition to N-Unprotected Ketimines (Poster Presentation), The Eleventh International Symposium on Integrated Synthesis (ISONIS-11), 2017.11.
31. Takashi Ohshima, New Zinc and Iron Catalysts for Transesterification (Oral Presentation), World Chemistry Conference & Exhibition, 2017.09.
32. Takashi Ohshima, Direct Catalytic Asymmetric Addition to N-Unprotected Ketimines (Plenary Lecture), International Symposium on Pure & Applied Chemistry (ISPAC) 2017, 2017.06.
33. Takashi Ohshima, Direct Catalytic Asymmetric Addition of Various Nucleophiles to N-Unprotected Ketimines (Oral Presentation), The 19th IUPAC International Symposium on Organometallic Chemistry Directed Towards Organic Synthesis (OMCOS19), 2017.06.
34. Takashi Ohshima, Direct Catalytic Asymmetric Addition of Various Nucleophiles to N-Unprotected Ketimines(Oral Presentation), International Symposium on Green Chemistry 2017 (ISGC-2017), 2017.05.
35. Takashi Ohshima, Ryo Yazaki, Keisuke Tokumasu, Direct Catalytic Chemoselective α-Amination of Acylpyrazoles: A Concise Route to Unnatural α-Amino Acid Derivatives, International Symposium on Catalysis and Fine Chemicals (C&FC2016), 2016.11.
36. Takashi Ohshima, Zn-Catalyzed Direct Alkynylation of N-Unprotected Trifluoromethyl Ketimines, The11th International Conference on Cutting-edge Organic Chemistry in Asia (ICCEOCA-11), 2016.10.
37. Takashi Ohshima, Kazuhiro Morisaki, Hiroyuki Morimoto, Zn-Catalyzed Direct Alkynylation of N-Unprotected Trifluoromethyl Ketimine, The 11th International Conference on Cutting-Edge Organic Chemistry in Asia (ICCEOCA-11) & The 2nd Advanced Research Network on Cutting-Edge Organic Chemistry in Asia (ARNCEOCA-2), 2016.10.
38. Takashi Ohshima, Catalytic Chemoselective Conjugate Addition of Alcohol over Amine, The 2nd HU-TMU-KU Joint Symposium for Pharmaceutical Sciences, 2016.09.
39. Takashi Ohshima, Rhodium-Catalyzed Direct Enantioselective Alkynylation of Ketimines: Mechanistic Studies and Expansion of Substrate Generality, The 3rd International Conference on Organometallics and Catalysis 2016 (OM&Cat-2016), 2016.08.
40. Takashi Ohshima, Direct Catalytic Chemoselective α-Amination of Acylpyrazoles:A Concise Route to Unnatural α-Amino Acid Derivatives, International Symposium on Pure & Applied Chemistry (ISPAC2016), 2016.08.
41. Takashi Ohshima, Ryo Yazaki, Keisuke Tokumasu, Direct Catalytic Chemoselective α-Amination of Acylpyrazoles, The 27th International Conference on Organometallic Chemistry (ICOMC 2016), 2016.07.
42. Takashi Ohshima, Dinuclear Iron(III) Catalyzed O-Selective Acylation of Aliphatic and Aromatic Amino Alcohols and Transesterification of tert-Alcohols, The International Symposium on Homogeneous Catalysis (ISHC) 2016, 2016.07.
43. Takashi Ohshima, New Zinc and Iron Catalysts for Transesterification, The 2nd International Symposium on Middle Molecular Strategy (ISMMS-2), 2016.07.
44. Takashi Ohshima, Rikiya Horikawa, Chika Fujimoto, Ryo Yazaki, μ-Oxo-Dinuclear Iron(III) Catalyzed O-Selective Acylation of Aliphatic and Aromatic Amino Alcohols and Transesterification of tert-Alcohols, French-Japanese Society of Medicinal and Fine Chemistry (FJS2016), 2016.05.
45. Takashi Ohshima, Ryo Yazaki, Keisuke Tokumasu, Direct Catalytic Chemoselective α-Amination of Acylpyrazoles:A Concise Route to Unnatural α-Amino Acid Derivatives
, The 12th International Symposium on Organic Reactions and The 6th German-Japanese Symposium on Electrosynthesis (ISOR-12 and GJSE-6), 2016.04.
46. Takashi Ohshima, Kazuhiro Morisaki, Masanao Sawa, Ryohei Yonesaki, Hiroyuki Morimoto, Rhodium-Catalyzed Direct Enantioselective Alkynylation of Ketimines: Mechanistic Studies and Expansion of Substrate Generality, The 2015 International Chemical Congress of Pacific Basin Societies (Pacifichem), 2015.12.
47. Takashi Ohshima, Rikiya Horikawa, Chika Fujimoto, Ryo Yazaki, Dinuclear iron complex-catalyzed transesterification: Synthesis of tert-butyl esters and unprecedented chemoselectivity, The 2015 International Chemical Congress of Pacific Basin Societies (Pacifichem), 2015.12.
48. Takashi Ohshima, Direct Catalytic Chemoselective Amination: A Concise Route to α-Amino Acid Derivatives, The 10th International Conference on Cutting-edge Organic Chemistry in Asia (ICCEOCA-10), 2015.11.
49. Takashi Ohshima, Direct Catalytic Chemoselective Amination: A Concise Route to α-Amino Acid Derivatives, The 10th International Conference on Cutting-edge Organic Chemistry in Asia (ICCEOCA-10), 2015.11.
50. Takashi Ohshima, Catalytic Chemoselective Conjugate Addition of Alcohol over Amine, The 18th IUPAC International Symposium on Organometallic Chemistry Directed Towards Organic Synthesis (OMCOS 18), 2015.06.
51. Takashi Ohshima, Kazuhiro Morisaki, Masanao Sawa, Ryohei Yonesaki, Hiroyuki Morimoto, Rhodium-Catalyzed Direct Enantioselective Alkynylation of Ketimines: Mechanistic Studies and Expansion of Substrate Generality, The 7th Spanish-Portuguese- Japanese Organic Chemistry Symposium (7th SPJ-OCS), 2015.06.
52. Takashi Ohshima, Development of Rhodium-Catalyzed Direct Enantioselective Alkynylation of α-Ketiminoesters, 8th Singapore International Chemical Conference (SICC8), 2014.12.
53. Takashi Ohshima, Catalyst Control of Chemoselectivity for the Development of New Green Processes, Nanyang Technological University Department Seminar, 2014.12.
54. Takashi Ohshima, Platinum-Catalyzed Direct Substitution of Allylic Alcohols with Nitrogen Nucleophiles and its Application to Short Total Synthesis of (-)-α-Kainic Acid, Vietnam Malaysia International Chemical Congress (VMICC), 2014.11.
55. Takashi Ohshima, Catalytic　Chemoselective Conjugate Addition of Alcohols over Amines, Malaysian International Chemical Congress (18MICC) , 2014.11.
56. Takashi Ohshima, Catalyst Control of Chemoselectivity for the Development of New Direct Catalyses, Asian Core Program Lectureship (Korea), 2014.10.
57. Takashi Ohshima, Catalyst Control of Chemoselectivity for the Development of New Direct Catalyses, Asian Core Program Lectureship (Korea), 2014.10.
58. Takashi Ohshima, Catalyst Control of Chemoselectivity for the Development of New Direct Catalyses, Asian Core Program Lectureship (Korea), 2014.09.
59. Takashi Ohshima, Catalytic　Chemoselective Conjugate Addition of Alcohols over Amines, 2014　Pusan-Kyushu International Joint Semina, 2014.08.
60. Takashi Ohshima, Platinum-Catalyzed Direct Substitution of Allylic Alcohols with Nitrogen and Carbon Nucleophiles and Its Application to Short Total Synthesis of (–)-α-Kainic Acid, IGER International Symposium on Chemical Science in Asia, 2014.05.
61. Takashi Ohshima, Catalyst Control of Chemoselectivity for the Development of New Direct Catalyses, Dr. Harisingh Gour University, 2014.01.
62. Takashi Ohshima, Ryo Yazaki, Shuhei Uesugi, Li Zhao, Catalytic Chemoselectivity Conjugate Addition of Alcohol over Amine, The 8th International Conference on Cutting-Edge Organic Chemistry in Asia (ICCEOCA-8)/The 4th New Phase International Conference on Cutting-Edge Organic Chemistry in Asia (NICCEOCA-4), 2013.11.
63. Takashi Ohshima, Catalyst Control of Chemoselectivity for the Development of New Direct Catalyses, 第23回 光学活性化合物シンポジウム, 2013.11.
64. Takashi Ohshima, Catalyst Control of Chemoselectivity for the Development of New Direct Catalyses, Lecture at Hangzhou Normal University, 2013.10.
65. Takashi Ohshima, Catalyst Control of Chemoselectivity for the Development of New Direct Catalyses, Lecture at Shanghai Institute of Materia Medica, 2013.10.
66. Takashi Ohshima, Catalyst Control of Chemoselectivity for the Development of New Direct Catalyses, Lecture at Fudan University, 2013.10.
67. Takashi Ohshima, Catalyst Control of Chemoselectivity for the Development of New Direct Catalyses, Lecture at East China Normal University, 2013.10.
68. Takashi Ohshima, Catalyst Control of Chemoselectivity for the Development of New Direct Catalyses, Lecture at Shanghai Institute of Organic Chemistry, 2013.10.
69. Takashi Ohshima, Catalyst Control of Chemoselectivity for the Development of New Direct Catalyses, Lecture at University of Science and Technology of China, 2013.10.
70. Takashi Ohshima, Catalyst Control of Chemoselectivity for the Development of New Direct Catalyses, Lecture at Nanjing University, 2013.10.
71. Takashi Ohshima, Kazuhiro Morisaki, Masanao Sawa, Jun-ya Nomaguchi, Hiroyuki Morimoto, Yosuke Takeuchi, Kazushi Mashima, Rh-Catalyzed Direct Enantioselective Alkylation of α-Ketoiminoesters, OMCOS17, 2013.07.
72. Takashi Ohshima, Kazuhiro Morisaki, Masanao Sawa, Jun-ya Nomaguchi, Hiroyuki Morimoto, Yosuke Takeuchi, Kazushi Mashima, Rh-Catalysed Direct Enantioselective Alkynylation of α-Ketiminoesters, Thieme Nagoya Symposium, 2013.05.
73. Takashi Ohshima, Development of Direct Transformations, Twenty-third French-Japanese Symposium on Medicinal and Fine Chemistry (FJS-2013), 2013.05.
74. Takashi Ohshima, Yuhei Shimizu, Hiroyuki Morimoto, Ming Zhang, Deacylation of Unactivated Amides to Amines Using Ammonium Salt-Accelerated Transamidation, The 7th International Conference on Cutting-Edge Organic Chemistry in Asia (ICCEOCA-7)/The 3rd New Phase International Conference on Cutting-Edge Organic Chemistry in Asia (NICCEOCA-3), 2012.12.
75. Takashi Ohshima, Kazushiro Morisaki, Jun-ya Nomaguchi, Hiroyuki Morimoto, Takahito Kawabata, Yosuke Takeuchi, Kazushi Mashima, Rh-Phebox-Catalyzed Asymmetric Alkynylation of α-Ketoesters and α-Ketoiminoesters, 13th Beligian Organic Synthesis Symposium BOSS 2012, 2012.07.
76. C1-Symmetric Rh-Phebox-Catalyzed Asymmetric Alkynylation of α-Keto Ester, The 1st Junior International Conference on Cutting-Edge Organic Chemistry in Asia (1st JACP), China, Dec.2011.
77. Takashi Ohshima, Development of New Direct Catalytic Reactions Using Tetranuclear Zinc Clusters, 14th Asian Chemical Congress (14 ACC), 2011.09.
78. Takashi Ohshima, Development of New Direct Catalytic Reactions Using Tetranuclear Zinc Clusters, The International Chemical Congress of Pacific Basin Societies, 2010.12.
Membership in Academic Society
  • Japanese Society for Chemical Biology
  • Catalysis Society of Japan
  • KINKA CHEMICAL SOCIETY
  • The Chemical Society of Japan
  • The Japanese Society of Process Chemistry
  • American Chemical Society
  • The Society of Synthetic Organic Chemistry, Japan
  • The Pharmaceutical Society of Japan
Awards
  • Direct Catalytic Asymmetric Addition to N-Unprotected Ketimines
  • Lanthanum(III) Triflate-Catalyzed Direct Amidation of Esters
  • The Asian Core Program Lectureship Award, The 8th International Conference on Cutting-Edge Organic Chemistry in Asia /The 4th New Phase International Conference on Cutting-Edge Organic Chemistry in Asia, Catalytic Chemoselectivity Conjugate Addition of Alcohol over Amine, Nov. 2013
  • The Asian Core Program Lectureship Award, The 7th International Conference on Cutting-Edge Organic Chemistry in Asia /The 3rd New Phase International Conference on Cutting-Edge Organic Chemistry in Asia, Deacylation of Unactivated Amides to Amines Using Ammonium Salt-Accelerated Transamidation, Dec.2012
  • Development of Environmentally Benign Direct Reactions Using Multinuclear Metal Cluster Catalysts
  • Development of Protecting Free Catalytic O-Selective Acylation of Aminoalcohols, JSPC Award for Excellence 2008, The Japanese Society for Process Chemistry, Dec. 2008
Educational
Other Educational Activities
  • 2015.03.
  • 2016.01, Global Initiative of Academic Network (GIAN) Programme
    Department of Chemistry, School of Chemical Sciences and Technology, Dr. Harisingh Gour Vishwavidyalaya Sagar (India).


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