Faculty Profiles - ABE Takumi

Papers - ABE Takumi

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2‐Hydroxy‐3‐(Pyrrolidin‐1‐yl)‐Indolines: A Platform for Accessing Decorated Deaminokynurenines Enabled by a Double Tautomeric Control Reviewed

Keisuke Tokushige, Takumi Abe

Asian Journal of Organic Chemistry 2025.5

One-pot Stereoselective Synthesis of trans-2,3-Diaminoindolines through Differentiated 2,3-Diamination of Electrophilic Indolines

Yuito Kobori, Keisuke Tokushige, Takumi Abe

2025.4

Molecular Iodine-Catalyzed Synthesis of 3,3-Disubstituted Isatins: Total Synthesis of Indole Alkaloid, 3,3-Dimethoxy-2-oxindole Invited Reviewed

Keisuke Tokushige, Shota Asai, Takumi Abe

Chemistry 2025.3

Perspectives of traditional herbal medicines in treating retinitis pigmentosa Reviewed

Shihui Liu, Toshihiko Matsuo, Chie Matsuo, Takumi Abe, Jinghua Chen, Chi Sun, Qing Zhao

Frontiers in Medicine 2024.12

Authorship：Corresponding author Language：English Publishing type：Research paper (scientific journal)

<jats:p>Medicinal plants, also known as herbs, have been discovered and utilized in traditional medical practice since prehistoric times. Medicinal plants have been proven rich in thousands of natural products that hold great potential for the development of new drugs. Previously, we reviewed the types of Chinese traditional medicines that a Tang Dynasty monk Jianzhen (Japanese: Ganjin) brought to Japan from China in 742. This article aims to review the origin of Kampo (Japanese traditional medicine), and to present the overview of neurodegenerative diseases and retinitis pigmentosa as well as medicinal plants in some depth. Through the study of medical history of the origin of Kampo, we found that herbs medicines contain many neuroprotective ingredients. It provides us a new perspective on extracting neuroprotective components from herbs medicines to treat neurodegenerative diseases. Retinitis pigmentosa (one of the ophthalmic neurodegenerative diseases) is an incurable blinding disease and has become a popular research direction in global ophthalmology. To date, treatments for retinitis pigmentosa are very limited worldwide. Therefore, we intend to integrate the knowledge and skills from different disciplines, such as medical science, pharmaceutical science and plant science, to take a new therapeutic approach to treat neurodegenerative diseases. In the future, we will use specific active ingredients extracted from medicinal plants to treat retinitis pigmentosa. By exploring the potent bioactive ingredients present in medicinal plants, a valuable opportunity will be offered to uncover novel approaches for the development of drugs which target for retinitis pigmentosa.</jats:p>

DOI： 10.3389/fmed.2024.1468230

Potassium tert‐Butoxide‐Mediated Ring‐Opening of Indolines: Concise Synthesis of 2‐Vinylanilines Invited Reviewed

Keisuke Tokushige, Shota Asai, Takumi Abe

Asian Journal of Organic Chemistry 2024.11

Authorship：Last author,　Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：Wiley

A concise and metal‐free procedure has been developed for the synthesis of 2‐vinylanilines. Reactions of indolines with tert‐BuOK in DMSO afford the decorated 2‐vinylanilines in yields up to 92%. In addition, the 2, or 3‐substituted indolines could be converted to trisubstituted alkenes. Also, the protocol can be scaled to afford gram quantities of the decorated 2‐vinylanilines.

DOI： 10.1002/ajoc.202400552

Azidoindolines—From Synthesis to Application: A Review Invited Reviewed

Takumi Abe

Chemistry 2024.7

Indoline hemiaminals: a platform for accessing anthranilic acid derivatives through oxidative deformylation Reviewed

Keisuke Tokushige, Yuito Kobori, Shota Asai, Takumi Abe

Organic & Biomolecular Chemistry 2024.7

Authorship：Last author,　Corresponding author Language：English Publishing type：Research paper (scientific journal)

<jats:p>Herein, we introduce a new synthetic protocol using 2-aminobenzoyl surrogates, allowing concise entry to decorated 2-aminobenzoyl derivatives in the absence of transition metals, acid chlorides, and specific reagents.</jats:p>

DOI： 10.1039/d4ob01218f

Formal One Carbon Deletion of Indoline Hemiaminals under Tautomeric Control to Access 2-Aminobenzyl Compounds Reviewed

Keisuke Tokushige, Takumi Abe

The Journal of Organic Chemistry 2024.7

Switchable Synthesis of 3-Aminoindolines and 2’-Aminoarylacetic Acids Using Grignard Reagents and 3-Azido-2-hydroxyindolines Reviewed

Toshiki Yamashiro, Takumi Abe

Chemical Communications 2024.5

Authorship：Last author,　Corresponding author Language：English Publishing type：Research paper (scientific journal)

<jats:p>The switchable synthesis of 3-aminoindolines and 2’-aminoaryl acetic acids from the same substrates, 3-azido-2-hydroxyindolines, was developed through denitogenative electrophilic amination of Grignard reagents. The key to success is the serendipitous...</jats:p>

DOI： 10.1039/d4cc01448k

Synthetic strategies for the construction of C3–N1′ bisindoles Reviewed

Takumi Abe

Organic & Biomolecular Chemistry 2024.1

Authorship：Lead author,　Last author,　Corresponding author Language：English Publishing type：Research paper (scientific journal)

<jats:p>Natural products having a C3–N1′ bisindole framework are unique structures with potential axial chirality. This minireview summarizes the recent progress of the methodology for constructing C3–N1′ bisindoles along with the possible mechanism.</jats:p>

DOI： 10.1039/d3ob02089d

Concise Synthesis of Thiazolo[4,5‐b]indoles via Ring Switch/Cyclization Sequences Reviewed

Koji Yamada, Tetsu Tsubogo, Hikaru Kanazawa, Sayaka Ishizuka, Koutaro Ohyama, Masaki Kaida, Takumi Abe

European Journal of Organic Chemistry 2023.12

Total Synthesis of the Proposed Structure of Indolyl 1,2-Propanediol Alkaloid, 1-(1H-Indol-3-yloxy)propan-2-ol Invited Reviewed

Momoko Kimata, Takumi Abe

Chemistry 2023.12

On Demand Synthesis of C3-N1' Bisindoles by a Formal Umpolung Strategy: First Total Synthesis of (±)-Rivularin A. Reviewed International journal

Keisuke Tokushige, Takumi Abe

Chemistry (Weinheim an der Bergstrasse, Germany) e202302963 2023.11

Authorship：Last author,　Corresponding author Language：English Publishing type：Research paper (scientific journal)

In this work, a straightforward synthesis of C3-N1' bisindolines is achieved by a formal umpolung strategy. The protocols were tolerant of a wide variety of substituents on the indole and indoline ring. In addition, the C3-N1' bisindolines could be converted to C3-N1' indole-indolines and C3-N1'-bisindoles. Also, we have successfully synthesized (±)-rivularin A through a biomimetic late-stage tribromination as a key step.

DOI： 10.1002/chem.202302963

Oxytrofalcatin Puzzle: Total Synthesis and Structural Revision of Oxytrofalcatins B and C Reviewed

Kazuma Sugitate, Toshiki Yamashiro, Ibuki Takahashi, Koji Yamada, Takumi Abe

The Journal of Organic Chemistry 88 ( 14 ) 2023.7

One-Pot Synthesis of Core Structure of Shewanelline C Using an Azidoindoline Reviewed

Toshiki Yamashiro, Keisuke Tokushige, Takumi Abe

The Journal of Organic Chemistry 88 ( 6 ) 3992 - 3997 2023.3

Aluminum-Catalyzed Cross Selective C3–N1′ Coupling Reactions of N-Methoxyindoles with Indoles Invited Reviewed

Keisuke Tokushige, Toshiki Yamashiro, Seiya Hirao, Takumi Abe

Chemistry 5 ( 1 ) 452 - 462 2023.3

Authorship：Last author,　Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：MDPI AG

C3–N1′ bond formation of bisindoles has been a great challenge due to the intrinsic reactivity of indoles as both C3 and N1-nucleophilic character. Herein, we demonstrate an C3–N1′ cross-coupling reaction of indoles using N-methoxyindoles as N-electrophilic indole reagents in the presence of Lewis acid. The bisindoles generated in this transformation are latent C3-nucleophile, allowing them to be used as strategic intermediates in sequential C3–N1′–C3′–N1″ triindole formations. The potential synthetic usefulness of this sequential transformation was highlighted upon application to the construction of C3–N1 looped polyindoles.

DOI： 10.3390/chemistry5010033

Revisiting Cryptocyanine Dye, NK-4, as an Old and New Drug: Review and Future Perspectives Reviewed

Shihui Liu, Toshihiko Matsuo, Takumi Abe

International Journal of Molecular Sciences 24 ( 5 ) 2023.2

Synthesis of Spiro[indole-3,3′-pyrrolidine]-2′-(thi)ones Reviewed

Motohiro Yasui, Haruna Ohbu, Maho Ishikawa, Tatsuhito Yoshida, Norihiko Takeda, Seiya Hirao, Takumi Abe, Masafumi Ueda

The Journal of Organic Chemistry 88 ( 2 ) 1093 - 1106 2023.1

Outstanding Reviewers for RSC Advances in 2022

Takumi Abe

RSC Advances 2023

Traditional Chinese Medicines and Prescriptions Brought from China to Japan by a Monk (Jianzhen, Japanese: Ganjin): A Historical Review Invited Reviewed

Shihui Liu, Toshihiko Matsuo, Chie Matsuo, Takumi Abe

Compounds 2 ( 4 ) 267 - 284 2022.10

Authorship：Last author,　Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：MDPI AG

(1) Background: Japanese Kampo medicine has its origin in ancient Chinese medicine. In 742, a Tang Dynasty monk named Jianzhen (Ganjin) was invited by Japanese clerics to visit Japan and teach commandments in Buddhism. Because of the dangers of the voyage and also other obstacles, he took 11 years to reach Japan on the sixth voyage and he was blind when he arrived in Japan. He was the first person in China to go to Japan to establish the Buddhism commandments, and he was also the first person in Japan to directly teach traditional Chinese medicine. Until now, there have been few reports in English about the details of the Chinese herbal medicines he brought to Japan, including the types of herbal medicines, pharmacological activities, and formulations. In the review, we systematically and comprehensively summarized Jianzhen’s life from the standpoint of his medical and pharmaceutical knowledge and the types and pharmacological activities of Chinese herbal medicines and prescriptions that were brought to Japan by Jianzhen; (2) Methods: A review was made on the relevant literature written by Chinese, Japanese, and English languages regarding the medical and pharmacological knowledge of Jianzhen, the 36 Chinese herbal medicines brought to Japan by Jianzhen, and the pharmacological and therapeutic effects of these 36 herbal medicines, as well as their formulations; (3) Results: The review of the literature proved that Jianzhen’s prescriptions served as a basis for current herbal medicines (Kampo) in Japan. In the process of the literature search, we found a book entitled Jianshangren (Holy Priest Jianzhen)’s Secret Prescription, which recorded the complete prescription of the 36 traditional Chinese medicines Jianzhen brought to Japan; (4) Conclusions: Jianzhen is one of the ancestors of traditional Chinese medicine/Kampo medicine, and he brought traditional Chinese medicine and medical books to Japan for patients. He made important contributions to the development of traditional Chinese medicine in Japan.

DOI： 10.3390/compounds2040022

First Total Synthesis of Reassigned Echinosulfonic Acid D Reviewed

Takumi Abe, Ren Nakajima, Toshiki Yamashiro, Daisuke Sawada

Journal of Natural Products 85 ( 8 ) 2022.8

Outstanding Reviewers for Organic & Biomolecular Chemistry in 2021

Takumi Abe

Organic & Biomolecular Chemistry 20 ( 28 ) 5499 - 5499 2022.7

Language：English Publishing type：Research paper (scientific journal) Publisher：Organic & Biomolecular Chemistry

<jats:p>We would like to take this opportunity to highlight the Outstanding Reviewers for <jats:italic>Organic & Biomolecular Chemistry</jats:italic> in 2021, as selected by the editorial team for their significant contribution to the journal.</jats:p>

DOI： 10.1039/D2OB90069F

Indole Editing Enabled by HFIP-Mediated Ring-Switch Reactions of 3-Amino-2-Hydroxyindolines Reviewed

Abe, T., Yamashiro, T., Shimizu, K., Sawada, D.

Chemistry - A European Journal 28 ( 37 ) 2022.5

Chemo- and Site-Selective Replacement of N-Terminal Carbamates in Peptides Reviewed

Miho Ibara, Takumi Abe, Daisuke Sawada

Organic Letters 2022.3

Synthesis of 2-monosubstituted indolin-3-ones by cine-substitution of 3-azido-2-methoxyindolines Invited Reviewed

Toshiki Yamashiro, Takumi Abe, Daisuke Sawada

Organic Chemistry Frontiers 9 ( 7 ) 1897 - 1903 2022.2

Authorship：Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：Royal Society of Chemistry ({RSC})

We have developed an efficient reaction of 3-azido-2-methoxyindolines with <italic>O</italic>-nucleophiles in the presence of a Lewis acid, affording 2-monoacyloxy or alkoxy indolin-3-ones.

DOI： 10.1039/D2QO00048B

Cis-3-Azido-2-Methoxyindolines as Safe and Stable Precursors to Overcome the Instability of Fleeting 3-Azidoindoles Reviewed International journal

Toshiki Yamashiro, Takumi Abe, Masaru Tanioka, Shinichiro Kamino, Daisuke Sawada

Chemical Communications 57 ( 98 ) 13381 - 13384 2021.11

Authorship：Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：Royal Society of Chemistry (RSC)

Use of 3-azidoindoles in organic synthesis remains difficult task owing to their instabilities. Herein, we report a general and concise approach for tackling this problem by using 3-azidoindole surrogates. The...

DOI： 10.1039/d1cc06033c

Synthesis of α-substituted indolylacetamide using acetonitriles as acetamide enolate equivalents through O-transfer reactions. Reviewed International journal

Takumi Abe, Kenta Noda, Daisuke Sawada

Chemical communications (Cambridge, England) 57 ( 61 ) 7493 - 7496 2021.7

Authorship：Lead author,　Corresponding author Language：English Publishing type：Research paper (scientific journal)

We introduce readily available ammonium hemiaminals as O-transfer reagents and commercially available acetonitriles as a primary amide enolate precursor. The combination serves as an amide enolate equivalent, thereby providing one-pot access to α-substituted indolylacetamides. A broad substrate scope and good functional group tolerance as well as gram-scale synthesis make this protocol highly attractive. Mechanistic experiments suggest that the cyano group is trapped by a hydroxy group of hemiaminals en route to the desired primary amides under metal-free conditions.

DOI： 10.1039/d1cc02821a

A metal-, oxidant-, and fluorous solvent-free synthesis of alpha-indolylketones enabled by an umpolung strategy Reviewed

Takumi Abe, Seiya Hirao, Toshiki Yamashiro

CHEMICAL COMMUNICATIONS 56 ( 70 ) 10183 - 10186 2020.9

Authorship：Lead author,　Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：ROYAL SOC CHEMISTRY

Enamines undergo alpha-indolization with ammonium salts in the presence of Et3N to form alpha-indolylketones. This is the first example of transition metal-, oxidant-, and fluorous solvent-free alpha-indolization of ketones. Key to the success of this convenient protocol was the use ofin situgenerated electrophilic indole species, as well as the use of enamines as a ketone enolate equivalent.

DOI： 10.1039/d0cc04795c

レセルピンの立体化学表記の訂正

Takumi Abe

ファルマシア 2020.8

Rapid access to indole-fused bicyclo[2.2.2]octanones by merging umpolung strategy and molecular iodine as a green catalyst Reviewed

Takumi Abe

Organic & Biomolecular Chemistry 2020.5

Authorship：Lead author,　Corresponding author Language：English Publishing type：Research paper (scientific journal)

<p>One-pot synthesis of indole-fused bicyclo[2.2.2]octanones from DiMeOIN and 2-cyclohexen-1-one are accomplished under iodine catalyst. This simple and metal-free conditions provides a practical tool to construct Csp3-rich complex molecules via oxidative...</p>

DOI： 10.1039/d0ob01038c

Revisiting 2-Alkoxy-3-bromoindolines: Control C-2 vs. C-3 Elimination for Regioselective Synthesis of Alkoxyindoles. Reviewed

Takumi Abe, Yuta Kosaka, Takaaki Kawasaki, Yuki Ohata, Toshiki Yamashiro, Koji Yamada

Chemical & pharmaceutical bulletin 68 ( 6 ) 555 - 558 2020

Authorship：Lead author,　Corresponding author Language：English Publishing type：Research paper (scientific journal)

The regioselective synthesis of both 2- and 3-alkoxyindoles from a common intermediate, 2-alkoxy-3-bromoindolines (ROBIN), is described. The 2-alkoxyindoles are obtained by a base-promoted regioselective elimination of HBr from ROBIN, whereas the synthesis of 3-alkoxyindoles is achieved by a silver-mediated alkoxylation followed by an acid-promoted elimination of alkoxide. This key elimination features the complete regioselectivity and no need for catalysts, that makes it have potential synthetic applications. Furthermore, this protocol is user friendly because ROBIN is able to be prepared from commercially available indoles and is a bench-stable easy-to-handle crystalline substrate, thus allowing the concise synthesis of a variety of both 2- and 3-alkoxyindoles.

DOI： 10.1248/cpb.c20-00135

2,3-Dimethoxyindolines: a latent electrophile for SNAr reactions triggered by indium catalysts Reviewed

Seiya Hirao, Toshiki Yamashiro, Kyouka Kohira, Naoki Mishima, Takumi Abe

Chemical Communications 2020

A Mild Bischler–Napieralski-Type Cyclization of Trichloromethyl Carbamates for the Synthesis of β-Carbolinones Reviewed

Takumi Abe

HETEROCYCLES 101 ( 1 ) 2020

Development and Application of Indole-2,3-epoxide Surrogates Reviewed

Abe Takumi, Yamada Koji, Nishi Takahide

Journal of Synthetic Organic Chemistry, Japan 78 ( 6 ) 597 - 607 2020

Authorship：Lead author,　Corresponding author Language：Japanese Publisher：The Society of Synthetic Organic Chemistry, Japan

<p>C3-Nucleophilic substitution of indoles has been limited because the transformation requires an umpolung of the C3 position of indoles. Among the indole derivatives, indole-2,3-epoxides could be potentially be used as C3-electrophilic reagents due to the electrophilic nature of the C2 and C3 positions. However, their use as C3 electrophilic reagents has not been possible so far due to their instability.</p><p>We describe a novel and bench stable surrogate of indole-2,3-epoxide, 2-hydroxyindoline-3-triethylammonium bromide (HITAB), which was found to be a convenient reagent for formal C3-electrophilic reactions of indoles with nucleophiles. By taking advantage of the nucleophilic character of the oxygen of the 2-hydroxyindoline, interrupted retro-Claisen and interrupted Feist-Bénary reactions with 1,3-dicarbonyl compounds, one-pot formation of furodiindolines from 3-substituted indoles were achieved. Furthermore, we developed a novel cascade reaction of the indole-2,3-epoxide surrogate with γ-carbolines to access multiheterocyclic compounds containing both isotryptamines and pyrimido［1,6-<i>a</i>］indoles. This reaction utilizes the <i>in situ</i> formation of a bulky quaternary ammonium salt via ammonium exchange, which undergoes Hofmann elimination/vinylogous Mannich/retro-Mannich/cyclization cascade sequences. The synthetic potential of the ammonium salts was demonstrated by the short synthesis of cryptolepine, iheyamine A, racemocine B derivative, and neocryptolepine derivative.</p>

DOI： 10.5059/yukigoseikyokaishi.78.597

Rapid access to indole-fused bicyclo[2.2.2]octanones by merging the umpolung strategy and molecular iodine as a green catalyst

Abe, T., Hirao, S.

Organic and Biomolecular Chemistry 18 ( 22 ) 2020

Rapid access to indole-fused bicyclo[2.2.2]octanones by merging the umpolung strategy and molecular iodine as a green catalyst

Takumi Abe, Seiya Hirao

Organic & Biomolecular Chemistry 18 ( 22 ) 2020

Silver-Mediated Intramolecular Friedel–Crafts-Type Cyclizations of 2-Benzyloxy-3-bromoindolines: Synthesis of Isochromeno[3,4-b] indolines and 3-Arylindoles Reviewed

Toshiki Yamashiro, Koji Yamada, Haruka Yoshida, Yutaro Tomisaka, Takahide Nishi, Takumi Abe

Synlett 30 ( 20 ) 2247 - 2252 2019.11

Authorship：Last author,　Corresponding author Publishing type：Research paper (scientific journal)

© 2019 Georg Thieme Verlag. All rights reserved. We disclose a silver-mediated intramolecular Friedel-Crafts-type cyclization of 2-benzyloxy-3-bromoindolines to afford an untapped family of isochromeno[3,4-b[indolines and 3-arylindoles, in which deformylative arylation of 2-(4-methoxybenzyloxy)-3-bromoindolines is reported for the first time. The isochromeno[3,4-b[indolines can be readily transformed into other heterocyclic moieties.

DOI： 10.1055/s-0039-1690734

Total Synthesis of Fontanesine B and Its Isomer: Their Antiproliferative Activity against Human Colorectal Cancer Cells Reviewed International journal

Takumi Abe

Helvetica Chimica Acta 102 ( 7 ) 2019.6

Total Synthesis of Proposed Structure of Azepinobisindole Alkaloid Rhodozepinone Reviewed

Takumi Abe

HETEROCYCLES 98 ( 6 ) 2019.5

Revisiting Furodiindolines: One-Pot Synthesis of Furodiindolines Using Indole 2,3-Epoxide Surrogates and Their Synthetic Applications Reviewed

Takumi Abe, Sakura Aoyama, Masami Ohmura, Masato Taniguchi, Koji Yamada

Organic Letters 21 ( 9 ) 3367 - 3371 2019.4

Direct C4-Benzylation of Indoles via Tandem Benzyl Claisen/Cope Rearrangements Reviewed

Takumi Abe, Yuta Kosaka, Miku Asano, Natsuki Harasawa, Akane Mishina, Misato Nagasue, Yuri Sugimoto, Kazuaki Katakawa, Shunsuke Sueki, Masahiro Anada, Koji Yamada

Organic Letters 21 ( 3 ) 826 - 829 2019.2

Total synthesis of pyrano[3,2-e]indole alkaloid fontanesine B by a double cyclization strategy Reviewed

Tomoki Itoh, Yuusuke Chiba, Shunsuke Kawaguchi, Yuki Koitaya, Yuuma Yoneta, Koji Yamada, Takumi Abe

RSC Advances 9 ( 18 ) 10420 - 10424 2019

Authorship：Last author,　Corresponding author Publishing type：Research paper (scientific journal) Publisher：Royal Society of Chemistry ({RSC})

<p>The regioselective synthesis of pyrano[3,2-<italic>e</italic>]indole alkaloid fontanesine B have been accomplished by C4 Pictet–Spengler cyclization and Bischler–Napieralski-type cyclization of a trichloromethyl carbamate.</p>

DOI： 10.1039/C9RA02321F

Biomimetic Synthesis of Iheyamine A from Spirocyclic Oxindoles Reviewed

Takumi Abe, Koji Yamada, Syuhei Satake

HETEROCYCLES 99 ( 0 ) 379 - 379 2019

Double "open and Shut" Transformation of γ-Carbolines Triggered by Ammonium Salts: One-Pot Synthesis of Multiheterocyclic Compounds Reviewed

Takumi Abe, Haruka Shimizu, Shiori Takada, Takahiro Tanaka, Mai Yoshikawa, Koji Yamada

Organic Letters 20 ( 6 ) 1589 - 1592 2018.3

Authorship：Lead author,　Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：American Chemical Society

A novel cascade reaction of indole-2,3-epoxide equivalents with γ-carbolines by utilizing a double "open and shut" transformation to access multiheterocyclic compounds containing both isotryptamines and pyrimido[1,6-a]indoles has been developed. This strategy utilizes the in situ formation of a bulky quaternary ammonium salt via ammonium exchange, which undergoes Hofmann elimination/vinylogous Mannich/retro-Mannich/cyclization cascade sequences.

DOI： 10.1021/acs.orglett.8b00332

Dehydrative Mannich-Type Reaction for the Synthesis of Azepinobisindole Alkaloid Iheyamine A Reviewed

Takumi Abe, Koji Yamada

Organic Letters 20 ( 5 ) 1469 - 1472 2018.3

Authorship：Lead author,　Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：American Chemical Society

A concise synthesis of the azepinobisindole alkaloid iheyamine A from an indole-2,3-epoxide equivalent has been achieved. This method features a formal C3 electrophilic reaction of an indole-2,3-epoxide equivalent with tryptamine to form a 3-aminoindoline and a novel In-catalyzed dehydrative Mannich-type reaction of the hemiaminal to give the azepinobisindole core.

DOI： 10.1021/acs.orglett.8b00330

Synthesis of Phaitanthrin E and Tryptanthrin through Amination/Cyclization Cascade Reviewed

Takumi Abe, Masaru Terasaki

Helvetica Chimica Acta 101 ( 2 ) e1700284 2018.2

Authorship：Lead author,　Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：Wiley Blackwell

Phaitanthrin E was biomimetically synthesized from methyl indole-3-carboxylate and methyl anthranilate or anthranilic acid using the ester group as an activating group. The reaction proceeds through NCS-mediated dearomatization/TFA-catalyzed protonation of indolenine/C(2) amination/Et3N-promoted aromatization and cyclization in one-pot procedure. This method is capable of converting simple biomass materials to phaitanthrin E. The synthesis not only allows assessment of antiproliferative activity, but also affords experimental support for the hypothetical biosynthetic pathway of phaitanthrin E. The resulting phaitanthrin E derivatives were evaluated for in vitro antiproliferative activity against human colorectal cancer cells (DLD-1). The biogenetic intermediate of phaitanthrin E showed higher antiproliferative activity than the natural product, phaitanthrin E. Furthermore, a concise synthesis of tryptanthrin is also accomplished from indole-3-carbaldehyde and methyl anthranilate using the aldehyde group as an activating group.

DOI： 10.1002/hlca.201700284

Nazarov cyclization of an indolyl vinyl ketone promoted by acetyl chloride and sodium iodide: Formal synthesis of Bruceolline e Reviewed

Takumi Abe

Heterocycles 96 ( 3 ) 490 - 500 2018

Authorship：Lead author,　Last author,　Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：Japan Institute of Heterocyclic Chemistry

An acetyl chloride/NaI-mediated Nazarov-type cyclization of an indolyl vinyl ketone was developed to give a cyclopenta[b]indole in high yield. An acyl Finkelstein reaction is a key feature for this unprecedented Nazarov-type cyclization.

DOI： 10.3987/COM-18-13866

Synthesis of Indoloquinazoline Alkaloids Using Cascade Reactions Reviewed

Abe Takumi

Journal of Synthetic Organic Chemistry, Japan 76 ( 8 ) 802 - 809 2018

Authorship：Lead author,　Last author,　Corresponding author Language：Japanese Publisher：The Society of Synthetic Organic Chemistry, Japan

<p>We describe the total synthesis of indolo[2,1-b]quinazoline alkaloids tryptanthrin (1a), candidine (2), phaitanthrins A (3), B (4), C (5), cruciferane (8), and cephalanthrin A (9) using oxidative cascade sequences as the key step. Phaitanthrin E (7a) was synthesized by a novel methodology that features a concise approach involving the intermolecular condensation and intramolecular aryl C-H amination mediated by Cu-complexes to construct the indolo[2,1-b]quinazoline core. Moreover, an acid catalyzed one-pot synthesis of phaitanthrin E (7a) via intermolecular amination/intramolecular cyclization cascade using NCS was also developed.</p>

DOI： 10.5059/yukigoseikyokaishi.76.802

Radical Cyclizations of Aryl Bromides for Synthesis of Cyclopenta[b]Indoles from Vince Lactam Reviewed

Takumi Abe, Tsuyoshi Morita, Koji Yamada

HETEROCYCLES 97 ( 0 ) 141 - 141 2018

An Ullmann N-arylation/2-amidation cascade by self-relay copper catalysis: one-pot synthesis of indolo[1,2-a]quinazolinones Reviewed

Takumi Abe, Yuka Takahashi, Yuki Matsubara, Koji Yamada

ORGANIC CHEMISTRY FRONTIERS 4 ( 11 ) 2124 - 2127 2017.11

Authorship：Lead author,　Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：ROYAL SOC CHEMISTRY

We have developed a self-relay copper(I)-catalyzed Ullmann N-arylation/2-amidation cascade to form functionalized indolo[1,2-a]quinazolinones in one-pot from easily available indoles with 2-bromobenzamides. This novel transformation features a tandem process of Ullmann-type coupling, activation of indolenine, and 2-amidation in the presence of a single copper catalyst. In addition, among the substituents of indoles at the C3 position, methyl carboxylate could act as an activating group in this Ullmann N-arylation/2-amidation cascade.

DOI： 10.1039/c7qo00549k

C4 Pictet-Spengler Reactions for the Synthesis of Core Structures in Hyrtiazepine Alkaloids Reviewed

Takumi Abe, Tomohiro Haruyama, Koji Yamada

SYNTHESIS-STUTTGART 49 ( 18 ) 4141 - 4150 2017.9

Authorship：Lead author,　Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：GEORG THIEME VERLAG KG

The hyrtiazepine alkaloids are a family of bisindole natural products that have the azepinoindole backbone. We developed a biomimetic approach by constructing the azepinoindole core in a one-pot manner through 1,4-diazabicyclo[2.2.2]octane/2,2,2-trifluoroethanol (DABCO/TFE) promoted Pictet-Spengler reaction onto the C-4 position of tryptophan. This strategy allowed the synthesis of common key structures of these families. The key intermediate can be converted into the 3H-pyrano[2,3-b:5,6-e']diindol intermediate present in hyrtimomines A and B, as well as the azepinoindole core present in fargesine.

DOI： 10.1055/s-0036-1588438

2-Hydroxyindoline-3-triethylammonium Bromide: A Reagent for Formal C3-Electrophilic Reactions of Indoles Reviewed

Takumi Abe, Takuro Suzuki, Masahiro Anada, Shigeki Matsunaga, Koji Yamada

ORGANIC LETTERS 19 ( 16 ) 4275 - 4278 2017.8

Authorship：Lead author,　Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：AMER CHEMICAL SOC

A novel indole-2,3-epoxide equivalent, 2-hydroxyindbline-3-triethylammonium bromide, was found, to be a convenient reagent for formal C3-electrophilic reactions of indoles with various nudeophiles. By taking advantage of the nudeophilie character of the oxygen of the 2-hydroxyindo-line the interrupted retro-Claisen interrupted Feist - Benary reactions, with 1,3-dicarbonyl compounds Were efficiently achieved.

DOI： 10.1021/acs.orglett.7b01940

A copper-catalyzed Ritter-type cascade via iminoketene for the synthesis of quinazolin-4(3H)-ones and diazocines Reviewed

Takumi Abe, Koshiro Kida, Koji Yamada

CHEMICAL COMMUNICATIONS 53 ( 31 ) 4362 - 4365 2017.4

Authorship：Lead author,　Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：ROYAL SOC CHEMISTRY

We have developed a copper-catalyzed Ritter-type reaction/cyclization cascade of anthranilic acids and nitriles, affording the quinazolin-4(3H)-ones. The cascade proceeds through a Ritter-type reaction capturing the iminoketene intermediates by nitriles. Furthermore, we found a novel Ritter-type reaction/condensation/intramolecular anti-Markovnikov hydroamination cascade, providing access to functionalized diazocines in one-pot.

DOI： 10.1039/c7cc01406f

Concise Syntheses of Hyrtioreticulins C and D via a C-4 Pictet-Spengler Reaction: Revised Signs of Specific Rotations Reviewed

Takumi Abe, Koji Yamada

JOURNAL OF NATURAL PRODUCTS 80 ( 2 ) 241 - 245 2017.2

Authorship：Lead author,　Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：AMER CHEMICAL SOC

The first syntheses of hyrtioreticulins C and D via a Pictet Spengler reaction at the C-4 position of the indole rings are described. The synthesis proceeds in only two steps from commercially available starting materials. In this Communication, the structures of the natural products were confirmed. Furthermore, we revise the signs of the specific rotations of hyrtioreticulins C and D.

DOI： 10.1021/acs.jnatprod.7b00008

One-pot synthesis of fused 2-pyridones from heteroarylacrylic acid via curtius rearrangement & microwave-assisted thermal electrocyclization Reviewed

Takashi Nishiyama, Noriyuki Hatae, Kaori Hayashi, Manami Obata, Kimiko Taninaka, Masahiro Yamane, Shota Oda, Takumi Abe, Minoru Ishikura, Satoshi Hibino, Tominari Choshi

Heterocycles 95 ( 1 ) 251 - 267 2017

Publishing type：Research paper (scientific journal)

©2017 The Japan Institute of Heterocyclic Chemistry. We investigated the one-pot synthesis of several fused 2-pyridone ring systems based on a Curtius rearrangement, followed by a microwave-assisted thermal electrocyclization of a 2-aza-6?-electron system including isocyanate. We synthesized seven heterocyclic compounds containing a fused 2-pyridone ring. In these results, the one-pot synthesis of fused 2-pyridone ring system 5 from (E)-acrylic acids 1 under microwave irradiation conditions was more effective than the conventional reaction conditions in terms of the yield and the reaction time.

DOI： 10.3987/COM-16-S(S)13

SYNTHESIS OF (+/-)-CEPHALANTHRIN A USING BAEYER-VILLIGER OXIDATION

Takumi Abe

Heterocycles 95 ( 1 ) 2017

Amination/Cyclization Cascade by Acid-Catalyzed Activation of Indolenine for the One-Pot Synthesis of Phaitanthrin E Reviewed

Takumi Abe, Koji Yamada

ORGANIC LETTERS 18 ( 24 ) 6504 - 6507 2016.12

Authorship：Lead author,　Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：AMER CHEMICAL SOC

We have developed a concise one-pot synthesis of phaitanthrin E derivatives, where simple starting materials undergo an acid-catalyzed intermolecular amination/intramolecular cyclization cascade.

DOI： 10.1021/acs.orglett.6b03466

Concise synthesis of carbazole-1,4-quinones and evaluation of their antiproliferative activity against HCT-116 and HL-60 cells Reviewed

Takashi Nishiyama, Noriyuki Hatae, Teruki Yoshimura, Sawa Takaki, Takumi Abe, Minoru Ishikura, Satoshi Hibino, Tominari Choshi

EUROPEAN JOURNAL OF MEDICINAL CHEMISTRY 121 561 - 577 2016.10

Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER FRANCE-EDITIONS SCIENTIFIQUES MEDICALES ELSEVIER

We report a convenient synthesis of carbazole-1,4-quinone alkaloid koeniginequinones A and B using a tandem ring-closing metathesis with the dehydrogenation reaction sequence under an O-2 atmosphere as an important step. Using this method, carbazole-1,4-quinones substituted at the 5-, 6-, 7-, and/or 8-positions have been synthesized. Moreover, 24 compounds, including koeniginequinones A and B, have been evaluated for their antiproliferative activity against HCT-116 and HL-60 cells, and the 6-nitro analog exhibited the most potent activity against both tumor cell types. (C) 2016 Elsevier Masson SAS. All rights reserved.

DOI： 10.1016/j.ejmech.2016.05.065

Synthesis of (±)-Cephalanthrin A using Baeyer-Villiger Oxidation

Takumi Abe

Heterocycles 2016.6

A ONE-POT SYNTHESIS OF PHAITANTHRIN E THROUGH INTERMOLECULAR CONDENSATION/INTRAMOLECULAR ARYL C-H AMINATION CASCADE Reviewed

Tomoki Itoh, Takumi Abe, Tominari Choshi, Takashi Nishiyama, Minoru Ishikura

HETEROCYCLES 92 ( 6 ) 1132 - 1136 2016.6

Language：English Publishing type：Research paper (scientific journal) Publisher：PERGAMON-ELSEVIER SCIENCE LTD

A one-pot synthesis of phaitanthrin E starting from methyl indole-3-carboxylate and isatoic anhydride through intermolecular condensation/intramolecular aryl C-H amination cascade was developed.

DOI： 10.3987/COM-16-13465

Other Link： http://orcid.org/0000-0003-1729-1097

Concise Total Syntheses of Pyrido[4,3-b]carbazole Alkaloids Using Copper-Mediated 6 pi-Electrocyclization Reviewed

Tomoki Itoh, Takumi Abe, Tominari Choshi, Takashi Nishiyama, Reiko Yanada, Minoru Ishikura

EUROPEAN JOURNAL OF ORGANIC CHEMISTRY 2016 ( 13 ) 2290 - 2299 2016.5

Language：English Publishing type：Research paper (scientific journal) Publisher：WILEY-V C H VERLAG GMBH

Concise syntheses of 9-methoxyellipticine, 3,4-dihydroellipticine (mu-alkaloid D), 1,2,3,4-tetrahydroellipticine, 2-methyl-1,2,3,4-tetrahydroellipticine, olivacine, 3,4-dihydroolivacine, (+/-)-guatambuine, and (+/-)-janetine were developed starting from hexatriene intermediates readily obtained by Pd-catalyzed tandem cyclization/cross-coupling reaction of indolylborates. The route enables the facile construction of pyrido[4,3-b]carbazoles by Cu-catalyzed 6 pi-electrocyclization and subsequent transformation of the pyridocarbazole intermediates into pyrido[4,3-b]carbazole alkaloids.

DOI： 10.1002/ejoc.201600246

TOTAL SYNTHESIS OF CARBAZOLE-1,4-QUINONE ALKALOID KOENIGINEQUINONES A AND B BASED ON A ONE-POT CYCLOCARBONYLATION PROCEDURE FROM 2-ALKENYL-3-IODOINDOLE Reviewed

Takashi Nishiyama, Nanase Satsuki, Satoshi Hibino, Mami Fujii, Takumi Abe, Minoru Ishikura, Tominari Choshi

HETEROCYCLES 93 ( 1 ) 84 - 100 2016.4

Language：English Publishing type：Research paper (scientific journal) Publisher：PERGAMON-ELSEVIER SCIENCE LTD

Total syntheses of koeniginequinones A and B, isolated from Murraya koenigii, were newly achieved by constructing of carbazole-1,4-quinone using a one-pot Pd-catalyzed cyclocarbonylation method with 2-(but-2-en-l-y1)-3-iodoindoles derived from known methyl 6-methoxyindole-2-carboxylate and methyl 5,6-dimethoxyindole-2-carboxylate, followed by desilylation, and an oxidation sequence.

DOI： 10.3987/COM-15-S(T)5

Palladium-catalyzed cross-coupling reaction of indolylborates and its application for the syntheses of indole alkaloids Reviewed

Takumi Abe, Minora Ishikura

Yuki Gosei Kagaku Kyokaishi/Journal of Synthetic Organic Chemistry 74 ( 2 ) 117 - 129 2016

Authorship：Lead author Language：Japanese Publisher：Society of Synthetic Organic Chemistry

In our continuing study of the reactivity and synthetic application of indolylborate as a versatile synthetic intermediate, we found that the use of indolylborate in palladium-catalyzed cross -coupling reaction is highly effective for the synthesis of indole derivatives. The present account deals with the results concerning a novel approach to indole alkaloids based on the use of the palladium-catalyzed cross-coupling. Dimeric indole alkaloid, yuechuke, was synthesized through the palladium-catalyzed carbonylative cross-coupling reaction. Pyridocarbazole alkaloids (ellip-ticine, olivacine, and their related alkaloids), and indolophenanthridine alkaloid (calothrixins A and B) were obtained by the use of cyclization/cross-coupling domino reaction. In addition, (CuOTf) 2 toluene complex was demonstrated to catalyze 6π-electrocyclization of hexatrienes, leading to pyrido [4,3-b] carbazoles.

DOI： 10.5059/yukigoseikyokaishi.74.117

Cu-MEDIATED OXIDATIVE DIMERIZATION OF SKATOLE TO TRYPTANTHRIN, AN INDOLO[2,1-b]QUINAZOLONE ALKALOID Reviewed

Tomoki Itoh, Takumi Abe, Shuhei Nakamura, Minoru Ishikura

HETEROCYCLES 91 ( 7 ) 1423 - 1428 2015.7

Pd-CATALYZED INTRAMOLECULAR OXIDATIVE COUPLING REACTION OF 1,1 '-CARBONYLDIINDOLES

Takumi Abe, Minoru Ishikura

HETEROCYCLES 90 ( 1 ) 673 - 680 2015.1

Authorship：Lead author Language：English Publishing type：Research paper (scientific journal) Publisher：PERGAMON-ELSEVIER SCIENCE LTD

The palladium-catalyzed intramolecular oxidative coupling reaction of 1,1'-carbonyldiindoles was achieved by using Pd(OAc)(2) and Cu(OAc)(2), producing 1,1'-carbonyl-2,2'-biindolyls, which were then converted to tjipanazoles D and I

DOI： 10.3987/COM-14-S(K)28

Simple indole alkaloids and those with a nonrearranged monoterpenoid unit Reviewed

Minoru Ishikura, Takumi Abe, Tominari Choshi, Satoshi Hibino

NATURAL PRODUCT REPORTS 32 ( 10 ) 1389 - 1471 2015

Language：English Publisher：ROYAL SOC CHEMISTRY

This review covers the literature on simple indole alkaloids and those with a nonrearranged monoterpenoid unit from the beginning of 2012 up to the end of 2013, which includes newly isolated alkaloids, structure determinations, total syntheses and biological activities.

DOI： 10.1039/c5np00032g

N-Substituted calothrixin B derivatives inhibited the proliferation of HL-60 promyelocytic leukemia cells Reviewed

Noriyuki Hatae, Risa Satoh, Hitomi Chiba, Takahiro Osaki, Takashi Nishiyama, Minoru Ishikura, Takumi Abe, Satoshi Hibino, Tominari Choshi, Chiaki Okada, Eiko Toyota

MEDICINAL CHEMISTRY RESEARCH 23 ( 11 ) 4956 - 4961 2014.11

Language：English Publishing type：Research paper (scientific journal) Publisher：SPRINGER BIRKHAUSER

Calothrixin B, whose structure consists of a pentacyclic indolo[3,2-j] phenanthridine framework, was originally isolated as a secondary metabolite from Calothrix cyanobacteria and was found to exhibit potent antiproliferative activity. In this study, treatment with 100 mu M of calothrixin B did not inhibit the proliferation of HL-60 promyelocytic leukemia cells, the result indicated that calothrixin B could possess weaker activity against leukemia cells. In a previous study of the structure-antiproliferative activity relationships of calothrixin B analogs, the tetracyclic 5H-pyrido[4,3-b] carbazole-4,11(6H)-dione structure, which does not include the benzene ring found in calothrixin B, was reported to be necessary for antiproliferative activity; however, the induction of substituents on the indole nitrogen atom of calothrixin B decreased the antiproliferative activity of the compound. To develop calothrixin B analogs with good antiproliferative activity against both HL-60 and HCT-116 cells, we synthesized various N-substituted calothrixin B analogs and assessed their activity. Compared with calothrixin B, N-OMe calothrixin B displayed almost the same or slightly stronger antiproliferative activity against HCT-116 cells, whereas the N-MOM analog demonstrated slightly weaker activity against these cells. These two analogs also inhibited proliferation of HL-60 cells, whereas calothrixin B did not exhibit antiproliferative activity toward these cells. Among calothrixin B analogs, N-OMe and N-MOM calothrixins B are cytotoxic against HCT-116 cells and not the lack of the effect on HL-60 cells.

DOI： 10.1007/s00044-014-1061-6

One-pot synthesis of tryptanthrin by the Dakin oxidation of indole-3-carbaldehyde Reviewed

Takumi Abe, Tomoki Itoh, Tominari Choshi, Satoshi Hibino, Minoru Ishikura

TETRAHEDRON LETTERS 55 ( 38 ) 5268 - 5270 2014.9

Authorship：Lead author Language：English Publishing type：Research paper (scientific journal) Publisher：PERGAMON-ELSEVIER SCIENCE LTD

A one-pot approach to indolo[2,1-b]quinazolines from indole-3-carbaldehydes through the Dakin oxidation was developed. It was shown that the reaction proceeded through the condensation of indole-3-carbaldehydes with isatoic anhydrides, derived in situ from indole-3-carbaldehydes by the Dakin oxidation, and further oxidation/cyclization steps. (C) 2014 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.tetlet.2014.07.113

A novel one-pot synthesis of carbazole-1,4-quinones through Pd-catalyzed cyclocarbonylation, desilylation and oxidation processes from 3-iodo-2-propenylindoles Reviewed

Mami Fujii, Takashi Nishiyama, Tominari Choshi, Nanase Satsuki, Takaya Fujiwaki, Takumi Abe, Minoru Ishikura, Satoshi Hibino

TETRAHEDRON 70 ( 9 ) 1805 - 1810 2014.3

Language：English Publishing type：Research paper (scientific journal) Publisher：PERGAMON-ELSEVIER SCIENCE LTD

novel one-pot synthesis of carbazole-1,4-quinone by consecutive Pd-catalyzed cyclocarbonylation, desilylation, and oxidation reactions is described. We propose a possible mechanism of the cyclocarbonylation reaction between 3-iodo-2-propenylindole and CO (1 atm) in the presence of a tributyl(vinyl)tin and Pd-catalyst and the resulting acylpalladium species was directly coupled with a terminal alkene to produce the carbazole-1,4-quinone. To our knowledge, this is the first example of this type of reaction. A new formal total synthesis of a carbazole-1,4-quinone alkaloid, murrayaquinone A was established using this reaction. (C) 2014 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.tet.2014.01.015

ONE-POT ACCESS TO 3,3 '-BISINDOLYLMETHANES THROUGH THE INTERMOLECULAR PUMMERER REACTION Reviewed

Takumi Abe, Toshiaki Ikeda, Tomoki Itoh, Noriyuki Hatae, Eiko Toyota, Minoru Ishikura

HETEROCYCLES 88 ( 1 ) 187 - 191 2014.1

Authorship：Lead author Language：English Publishing type：Research paper (scientific journal) Publisher：PERGAMON-ELSEVIER SCIENCE LTD

A one-pot synthesis of 3,3'-bisindolylmethanes was developed through the intermolecular Pummerer reaction using indole as a nucleophile.

DOI： 10.3987/COM-13-S(S)31

Effect of the orthoquinone moiety in 9,10-phenanthrenequinone on its ability to induce apoptosis in HCT-116 and HL-60 cells Reviewed

Noriyuki Hatae, Jun Nakamura, Tetsuo Okujima, Minoru Ishikura, Takumi Abe, Satoshi Hibino, Tominari Choshi, Chiaki Okada, Hiroko Yamada, Hidemitsu Uno, Eiko Toyota

BIOORGANIC & MEDICINAL CHEMISTRY LETTERS 23 ( 16 ) 4637 - 4640 2013.8

Language：English Publishing type：Research paper (scientific journal) Publisher：PERGAMON-ELSEVIER SCIENCE LTD

9,10-Phenanthrenequinone (9,10-PQ) is one of the most abundant quinones among diesel exhaust particulates. Recent data have suggested that quinones induce apoptosis in immune, epithelial and tumor cells, leading to respirator illness; however, the mechanisms by which quinones induce apoptosis and the structure required for this remain unknown. We studied the antitumor activity of 9,10-PQ analogs against two human tumor cell lines, HCT-116 colon tumor cells and HL-60 promyelocytic leukemia cells. The loss of the cis-orthoquinone unit in 9,10-PQ abrogated its ability to induce apoptosis in the two tumor cell lines, and the LC50 values of these analogs were indicated over 10 mu M. An analog of 9,10-PQ in which the biaryl unit had been deleted displayed a reduced ability to induce tumor cell apoptosis, while the analogs 1,10-phenanthroline-5,6-dione (9) and pyrene-4,5-dione (10), which also had modified biaryl units, exhibited increased tumor cell apoptotic activity. The cis-orthoquinone unit in 9,10-PQ was identified as essential for its ability to induce apoptosis in tumor cells, and its biaryl unit is also considered to influence orthoquinone-mediated apoptotic activity. (C) 2013 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.bmcl.2013.06.015

Biomimetic transamination of α-keto esters Reviewed

Takumi Abe

Yuki Gosei Kagaku Kyokaishi/Journal of Synthetic Organic Chemistry 71 ( 1 ) 62 - 63 2013.7

Authorship：Lead author,　Last author,　Corresponding author Language：Japanese Publisher：The Society of Synthetic Organic Chemistry, Japan

The development of biomimetic reactions is one of the major challenges for synthetic chemists, because mimicking these complicated reactions in the laboratory by simple catalytic systems is difficult to achieve in general. Vitamine B6-dependent aminotransferase-catalyzed transamination of α-keto acids from pyridoxamine is an important process to generate α-amino acids in nature. In this review, recent progresses on the biomimetic transamination of α-keto esters are described.

DOI： 10.5059/yukigoseikyokaishi.71.62

One-pot construction of 3,3′-bisindolylmethanes through Bartoli indole synthesis Reviewed

Takumi Abe, Shuuhei Nakamura, Reiko Yanada, Tominari Choshi, Satoshi Hibino, Minoru Ishikura

Organic Letters 15 ( 14 ) 3622 - 3625 2013.7

Authorship：Lead author Language：English Publishing type：Research paper (scientific journal)

A one-pot approach to 3,3′-bisindolylmethane derivatives from nitrobenzene derivatives through the Bartoli indole synthesis was developed, in which the acid used to quench the reaction markedly affected its outcome. Quenching the reaction with concd HCl produced 3,3′-bisindolylmethane in contrast to the formation of 7-substituted indole by quenching with NH 4Cl. © 2013 American Chemical Society.

DOI： 10.1021/ol401486s

Synthesis of indole compounds using multifunctional synthons Reviewed

Takumi Abe

Yakugaku Zasshi 133 ( 1 ) 99 - 106 2013

Authorship：Lead author,　Last author,　Corresponding author Language：Japanese Publisher：日本薬学会

This review describes a synthesis of indole compounds using multifunctional synthons. The multifunctional synthons, trienes and gramines, were respectively synthesized using Pd-catalyzed tandem cyclization/cross-coupling reaction of indolylborate with vinyl bromide, and reaction of indolylcuprate with iminium chloride. As an application of the multifunctional synthons to the indole alkaloids synthesis, we accomplished the total synthesis of ellipticine, 9-methoxyellipticine, 9-hydroxyellipticine, tetrahydroellipticine, μ-alkaloid B, μ-alkaloid D, calothrixin A, calothrixin B, tubifoline, and yuehchukene. We have also developed 6π-electrocyclization of hexatrienes catalyzed by Cu(I) trifluoromethanesulfonate toluene complexe, which is unprecedented. © 2013 The Pharmaceutical Society of Japan.

DOI： 10.1248/yakushi.12-00233

Simple indole alkaloids and those with a non-rearranged monoterpenoid unit Reviewed

Minoru Ishikura, Takumi Abe, Tominari Choshi, Satoshi Hibino

NATURAL PRODUCT REPORTS 30 ( 5 ) 694 - 752 2013

Language：English Publisher：ROYAL SOC CHEMISTRY

This review covers the literature on simple indole alkaloids and those with a non-rearranged monoterpenoid unit from the beginning of 2010 up to the end of 2011, which includes newly isolated alkaloids, structure determinations, total syntheses and biological activities.

DOI： 10.1039/c3np20118j

SHORT APPROACH TO BISINDOLE ALKALOID, YUEHCHUKENE, USING 2-INDOLYLCYANOCUPRATE

Takumi Abe, Hiroyuki Komatsu, Toshiaki Ikeda, Noriyuki Hatae, Eiko Toyota, Minoru Ishikura

HETEROCYCLES 86 ( 1 ) 505 - 513 2012.12

Authorship：Lead author Language：English Publishing type：Research paper (scientific journal) Publisher：PERGAMON-ELSEVIER SCIENCE LTD

A short total synthesis of a bisindole alkaloid, yuechukene, was achieved through the dimerization of beta-dehydroprenylindole generated in situ from 1-(indol-3-yl)-3-methylbut-2-en-1-amine.

DOI： 10.3987/COM-12-S(N)49

Total Synthesis of Calothrixins A and B by Palladium-Catalyzed Tandem Cyclization/Cross-Coupling Reaction of Indolylborate

Takumi Abe, Toshiaki Ikeda, Tominari Choshi, Satoshi Hibino, Noriyuki Hatae, Eiko Toyata, Reiko Yanada, Minoru Ishikura

EUROPEAN JOURNAL OF ORGANIC CHEMISTRY 2012 ( 26 ) 5018 - 5027 2012.9

Authorship：Lead author Language：English Publishing type：Research paper (scientific journal) Publisher：WILEY-V C H VERLAG GMBH

The palladium-catalyzed tandem cyclization/cross-coupling reaction of triethyl(indol-2-yl)borate with vinyl bromide was successfully used in the concise total synthesis of the indolophenanthridine alkaloids, calothrixins A and B.

DOI： 10.1002/ejoc.201200657

Synthesis and antimalarial activity of calothrixins A and B, and their N-alkyl derivatives Reviewed

Kohji Matsumoto, Tominari Choshi, Mai Hourai, Yoshito Zamami, Kenji Sasaki, Takumi Abe, Minoru Ishikura, Noriyuki Hatae, Tatsunori Iwamura, Shigeo Tohyama, Junko Nobuhiro, Satoshi Hibino

BIOORGANIC & MEDICINAL CHEMISTRY LETTERS 22 ( 14 ) 4762 - 4764 2012.7

Language：English Publishing type：Research paper (scientific journal) Publisher：PERGAMON-ELSEVIER SCIENCE LTD

We synthesized calothrixin B using our developed biomimetic method and derived N-alkyl-calothrixins A and B. The in vitro antimalarial activity of the calothrixin derivatives, including calothrixins A and B, against the Plasmodium falciparum FCR-3 strain was evaluated. All test compounds exhibited antimalarial activity over a concentration range of 6.4 x 10(-6)-1.2 x 10(-7) M. (C) 2012 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.bmcl.2012.05.064

Concise Total Synthesis of Calothrixins A and B Reviewed

Takumi Abe, Toshiaki Ikeda, Reiko Yanada, Minoru Ishikura

ORGANIC LETTERS 13 ( 13 ) 3356 - 3359 2011.7

Authorship：Lead author Language：English Publishing type：Research paper (scientific journal) Publisher：AMER CHEMICAL SOC

The concise total synthesis of calothrixins A and B has been accomplished by utilizing the one-pot formation of hexatriene as a key intermediate via the palladium-catalyzed tandem cyclization/cross-coupling reaction of triethyl(indo1-2-yl)borate. In another key transformation, the indolo[3,2-j]phenanthridine core was prepared in high yield via Cu(I)-mediated 6 pi-electrocyclization.

DOI： 10.1021/ol201107a

FACILE SYNTHESIS OF PYRANO[3,2-e]INDOLES VIA THE BASE-PROMOTED PICTET-SPENGLER REACTION OF N-b-BENZYLSEROTONIN

Koji Yamada, Sayaka Yamaguchi, Noriyuki Hatae, Takumi Abe, Tatsunori Iwamura, Minoru Ishikura

HETEROCYCLES 83 ( 4 ) 815 - 826 2011.4

Language：English Publishing type：Research paper (scientific journal) Publisher：PERGAMON-ELSEVIER SCIENCE LTD

A novel and simple protocol for the synthesis of 1-(2-aminoethyl)pyrano[3,2-e]indole derivatives has been developed using the Pictet-Spengler reaction of N-b-benzylserotonin with alpha,beta-unsaturated aldehydes in the presence of Et3N in 2-propanol or MeOH.

DOI： 10.3987/COM-11-12144

Metal-Catalyzed Reactions between 2-Azabicyclo[2.2.1]hept-5-en-3-ones and Arylboronic Acids Reviewed

Takumi Abe, Hiroyuki Takeda, Yumi Takahashi, Yoshihisa Miwa, Koji Yamada, Minoru Ishikura

EUROPEAN JOURNAL OF ORGANIC CHEMISTRY 2010 ( 17 ) 3281 - 3294 2010.6

Language：English Publishing type：Research paper (scientific journal) Publisher：WILEY-V C H VERLAG GMBH

Cu- and Rh-catalyzed coupling reactions of 2-azabicyclo[2.2.1]hept-5-en-3-ones (1) with arylboronic acids were successful carried out under microwave irradiation conditions and yielded N-aryl and C-aryl derivatives of 1, respectively.

DOI： 10.1002/ejoc.201000135

Other Link： http://orcid.org/0000-0003-1729-1097

Copper-Catalyzed Ritter-Type Reaction of Unactivated Alkenes with Dichloramine-T

Takumi Abe, Hiroyuki Takeda, Yoshihisa Miwa, Koji Yamada, Reiko Yanada, Minoru Ishikura

HELVETICA CHIMICA ACTA 93 ( 2 ) 233 - 241 2010

Language：English Publishing type：Research paper (scientific journal) Publisher：WILEY-V C H VERLAG GMBH

It was shown that dichloramine-T (1) reacted with cyclohexene in acetonitrile to give N'-(2-chlorocyclohexyl) amidine 2a and N-(2-chlorocyclohexyl)acetamide (3) via the competitive addition of acetonitrile and N-chloro-N-tosylamino anion to cyclohexenechloronium ion. This reaction can be catalyzed by Cu(OAc)(2), primarily affording 2a. Furthermore, the resulting 2a can be cyclized to benzimidazol 14a in good yield by treating with KOH in dioxane.

DOI： 10.1002/hlca.200900214

Simple indole alkaloids and those with a nonrearranged monoterpenoid unit Reviewed

Minoru Ishikura, Koji Yamada, Takumi Abe

NATURAL PRODUCT REPORTS 27 ( 11 ) 1630 - 1680 2010

Language：English Publisher：ROYAL SOC CHEMISTRY

This review covers the literature on simple indole alkaloids and those with a nonrearranged monoterpenoid unit, and includes newly isolated alkaloids, structure determinations, total syntheses and biological activities.

DOI： 10.1039/c005345g

Other Link： http://orcid.org/0000-0003-1729-1097

Revisiting AI-2 Quorum Sensing Inhibitors: Direct Comparison of Alkyl-DPD Analogues and a Natural Product Fimbrolide Reviewed

Colin A. Lowery, Takumi Abe, Junguk Park, Lisa M. Eubanks, Daisuke Sawada, Gunnar F. Kaufmann, Kim D. Janda

JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 131 ( 43 ) 15584 - + 2009.11

Language：English Publishing type：Research paper (scientific journal) Publisher：AMER CHEMICAL SOC

Quorum sensing (QS) systems have been discovered in a wide variety of bacteria, and mediate both intra- and interspecies communication. The AI-2-based QS system represents the most studied of these proposed interspecies systems and has been shown to regulate diverse functions such as bioluminescence, expression of virulence factors, and biofilm formation. As such, the development of modulatory compounds, both agonists and antagonists, is of great interest for the study of unknown AI-2-based QS systems and the potential treatment of bacterial infections. The fimbrolide class of natural products has exhibited excellent inhibitory activity against AI-2-based QS and as such may be considered the "gold standard" of AI-2 inhibitors. Thus, we sought to include a fimbrolide as a control compound for our recently developed alkyl-DPD panel of AI-2 modulators. Herein, we present a revised synthesis of a commonly studied fimbrolide as well as a direct comparison between the fimbrolide and alkyl-DPD analogues. We demonstrate that our alkyl-DPD analogues are more potent inhibitors of QS in both Vibrio harveyi and Salmonella typhimurium, the two organisms with defined AI-2 QS systems, and in doing so call into question the widely accepted use of fimbrolide-derived compounds as the "gold standard" of AI-2 inhibition.

DOI： 10.1021/ja9066783

Other Link： http://orcid.org/0000-0003-1729-1097

REACTION OF N-beta-BENZYLSEROTONIN WITH alpha,beta-UNSATURATED AND ARYL ALDEHYDES IN THE PRESENCE OF A BASE Reviewed

Koji Yamada, Yuichi Namerikawa, Takumi Abe, Minoru Ishikura

HETEROCYCLES 77 ( 2 ) 825 - 828 2009.2

Language：English Publishing type：Research paper (scientific journal) Publisher：PERGAMON-ELSEVIER SCIENCE LTD

The reaction of N-beta-benzylserotonin with alpha,beta-unsaturated and aryl aldehydes in the presence of a base produced 1H-azepino[5,4,3-cd]indoles.

DOI： 10.3987/COM-08-S(F)98

Other Link： http://orcid.org/0000-0003-1729-1097

RHODIUM-CATALYZED ARYLATION OF 2-AZABICYCLO[2.2.1]HEPT-5-EN-3-ONE WITH ARYLBORONIC ACIDS UNDER MICROWAVE IRRADIATION Reviewed

Takumi Abe, Hiroyuki Takeda, Yumi Takahashi, Yoshihisa Miwa, Koji Yamada, Minoru Ishikura

HETEROCYCLES 75 ( 12 ) 2931 - 2936 2008.12

Authorship：Lead author Language：English Publishing type：Research paper (scientific journal) Publisher：PERGAMON-ELSEVIER SCIENCE LTD

Rhodium-catalyzed arylation of 2-azabicyclo[2.2.1]hept-5-en-3-one was successfully performed by applying microwave irradiation.

DOI： 10.3987/COM-08-11483

Other Link： http://orcid.org/0000-0003-1729-1097

A concise approach to (+/-)-tubifoline based on the palladium-catalyzed cross-coupling reaction of indolylborate Reviewed

Minoru Ishikura, Norinobu Takahashi, Koji Yamada, Takumi Abe

HETEROCYCLES 75 ( 1 ) 107 - 118 2008.1

Language：English Publishing type：Research paper (scientific journal) Publisher：PERGAMON-ELSEVIER SCIENCE LTD

The palladium-catalyzed tandem cyclization-cross-coupling protocol using 1H-indol-2-yltrialkylborate (indolylborate) proved to be a versatile approach to the generation of 2-(4-piperidylmethyl)indole, which was successfully used for the preparation of (+/-)-tubifoline.

DOI： 10.3987/COM-07-11190

Other Link： http://orcid.org/0000-0003-1729-1097

Formal Synthesis of Olivacine via Indolylborate Reviewed

Minoru Ishikura, Norinobu Takahashi, Koji Yamada, Takumi Abe, Reiko Yanada

HELVETICA CHIMICA ACTA 91 ( 10 ) 1828 - 1837 2008

Language：English Publishing type：Research paper (scientific journal) Publisher：WILEY-V C H VERLAG GMBH

Palladium-catalyzed tandem cyclization - cross-coupling reaction of indolylborate 2 and vinyl bromide 5 was successfully applied in a short formal synthesis of olivacine. The reaction of 2 with 5 in the presence of Pd(OAc)(2) readily afforded three kinds of products, triene derivative 6 and vinylindole derivative 7, along with a small amount of the piperidine derivative 8 (Scheme 2). On the other hand, the reactions of 2 with bromide 10 or 15 were also examined (Schemes 4 and 5) and their outcome markedly depended oil the relative ease of ring closure as a function of ring size. Irradiation of 6 with a high-pressure pressure mercury lamp (-9; Scheme 2), followed by removal of the N-[(benzyloxy)carbonyl] group and subsequent oxidation afforded, after deprotection, pyridocarbazole 23, and the conversion of 23 to olivacine is known (Scheme 6).

DOI： 10.1002/hlca.200890195

Other Link： http://orcid.org/0000-0003-1729-1097

Copper-catalyzed N-arylation reaction of 2-azabicyclo[2.2.1]hept-5-en-3-one with arylboronic acids under microwave irradiation Reviewed

Takumi Abe, Hiroyuki Takeda, Koji Yamada, Minoru Ishikura

Heterocycles 76 ( 1 ) 133 - 136 2008

Authorship：Lead author Language：English Publishing type：Research paper (scientific journal)

Copper-catalyzed N-arylation reaction of 2-azabicyclo[2.2.1]hept-5-en-3-one (ABH) with arylboronic acids was successively performed in the presence of KOH and trimethylamine-N-oxide under microwave irradiation. © The Japan Institute of Heterocyclic Chemistry.

DOI： 10.3987/COM-07-S(N)6

Other Link： http://orcid.org/0000-0003-1729-1097

Asymmetric syntheses of diarylheptanoid natural products (-)-centrolobine and (-)-de-O-methylcentrolobine via hetero-Diels-Alder reaction catalyzed by dirhodium(II) tetrakis[(R)-3-(benzene-fused-phthalimido)-2-piperidinonate] Reviewed

Takuya Washio, Reika Yamaguchi, Takumi Abe, Hisanori Nambu, Masahiro Anada, Shunichi Hashimoto

TETRAHEDRON 63 ( 48 ) 12037 - 12046 2007.11

Language：English Publishing type：Research paper (scientific journal) Publisher：PERGAMON-ELSEVIER SCIENCE LTD

Catalytic asymmetric syntheses of (-)-centrolobine and (-)-de-O-methylcentrolobine have been achieved, incorporating a hetero-Diels-Alder (HDA) reaction between 4-aryl-2-silyloxy-1,3-butadienes and phenylpropargyl aldehyde derivatives as a key step. The HDA reaction using dirhodium(II) tetrakis[(R)-3-(benzene-fused-phthalimido)-2-piperidinonate], Rh-2(R-BPTPI)(4), as a chiral Lewis acid catalyst provides exclusively cis-2,6-disubstituted tetrahydropyran-4-ones in up to 93% ee. (C) 2007 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.tet.2007.09.003

Other Link： http://orcid.org/0000-0003-1729-1097

Catalytic enantioselective Amination of silyl enol ethers using chiral Dirhodium(II) carboxylates: Asymmetric formal synthesis of (-)-metazocine Reviewed

Masahiro Anada, Masahiko Tanaka, Takuya Washio, Minoru Yamawaki, Takumi Abe, Shunichi Hashimoto

ORGANIC LETTERS 9 ( 22 ) 4559 - 4562 2007.10

Language：English Publishing type：Research paper (scientific journal) Publisher：AMER CHEMICAL SOC

[GRAPHICS]
Dirhodium(II) tetrakis[N-tetrafluorophthaloyl-(S)-tert-leucinate], Rh-2(S-FPTTL)(4), is an exceptionally efficient catalyst for enantioselective aminations of silyl enol ethers derived from acyclic ketones or a,beta-enones with [N-(2-nitrophenyisulfonyl)imino]phenyliodinane (NsN=IPh), providing N-(2-nitrophenyisulfonyl)-alpha-amino ketones in high yields and with enantioselectivities of up to 95% ee. The effectiveness of the present catalytic protocol has been demonstrated by an asymmetric formal synthesis of (-)-metazocine.

DOI： 10.1021/o1702019b

Other Link： http://orcid.org/0000-0003-1729-1097

Catalytic enantioselective aziridination of alkenes using chiral dirhodium(II) carboxylates Reviewed

Minoru Yamawaki, Masahiko Tanaka, Takumi Abe, Masahiro Anada, Shunichi Hashimoto

HETEROCYCLES 72 709 - 721 2007.4

Language：English Publishing type：Research paper (scientific journal) Publisher：PERGAMON-ELSEVIER SCIENCE LTD

The enantioselective aziridination of alkenes with [N-(4-nitrophenylsulfonyl)imino]phenyliodinane catalyzed by dirhodium(II) tetrakis[N-tetrachlorophthaloyl-(S)-tert-leucinate], Rh-2(S-TCPTTL)(4), is described. While such enantioselectivities are highly dependent on the properties of the alkenes, 2,2-dimethylchromene was found to be a particularly suitable substrate which can be efficiently transformed into the aziridine product in 98% yield with 94% ee.

DOI： 10.3987/COM-07-S(K)63

Catalytic enantioselective tandem carbonyl ylide formation/1,3-dipolar cycloaddition reactions of alpha-diazo ketones with aromatic aldehydes using dirhodium(II) tetrakis[N-benzene-fused-phthaloyl-(S)-valinate] Reviewed

Hideyuki Tsutsui, Naoyuki Shimada, Takumi Abe, Masahiro Anada, Makoto Nakajima, Seiichi Nakamura, Hisanori Nambu, Shunichi Hashimoto

ADVANCED SYNTHESIS & CATALYSIS 349 ( 4-5 ) 521 - 526 2007.3

Language：English Publishing type：Research paper (scientific journal) Publisher：WILEY-V C H VERLAG GMBH

The first successful example of the enantioselective intermolecular 1,3-dipolar cycloaddition of a chiral dirhodium(II) catalyst-associated carbonyl ylide with an aromatic aldehyde dipolarophile is described. The tandem carbonyl ylide formation/cycloaddition reactions of 1-diazo-5-aryl-2,5-pentanediones with aromatic aldehydes using dirbodium(II) tetrakis[N-benzene-fused-phthaloyl-(S)-valinate] as a catalyst provide exclusively exo cycloadducts in up to 92% ee.

DOI： 10.1002/adsc.200600591

Investigation of the regioselectivity on the reaction of 2-indolylcyanocuprate with N-(prop-2-en-1-ylidene)aminium chloride derivatives Reviewed

Minoru Ishikura, Hiroyuki Komatsu, Koji Yamada, Takumi Abe, Reiko Yanada

HETEROCYCLES 71 ( 11 ) 2325 - 2329 2007

Practical synthesis of dirhodium(II) Tetrakis[N-phthaloyl-(S)-tert-leucinate] Reviewed

H Tsutsui, T Abe, S Nakamura, M Anada, S Hashimoto

CHEMICAL & PHARMACEUTICAL BULLETIN 53 ( 10 ) 1366 - 1368 2005.10

Language：English Publishing type：Research paper (scientific journal) Publisher：PHARMACEUTICAL SOC JAPAN

An efficient and reliable procedure for the preparation of dirhodium(II) tetrakis[N-phthaloyl-(S)-tert-leucinate], Rh-2(S-PTTL)(4), a universally effective catalyst for a range of enantioselective carbene transformations, is described. The N-phthaloylation of (S)-tert-leucine by the method of Bose with essentially no racemization is a key to this process.

DOI： 10.1248/cpb.53.1366

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