Details of the Researcher

PHOTO

Ozora Sasamoto
Section
Graduate School of Pharmaceutical Sciences
Job title
Assistant Professor
e-Rad No.
30982409

Papers 6

  1. Phosphazene Base t-Bu-P2-Catalyzed Substitution Reactions of para-Hydroxybenzyl Alcohols Peer-reviewed

    Ozora Sasamoto, Kyosuke Osaka, Kazutoshi Hayashi, Toshinobu Korenaga, Yoshinori Kondo, Masanori Shigeno

    Asian Journal of Organic Chemistry　2025/05/22

    Publisher: Wiley

    DOI： 10.1002/ajoc.202500407 　

    ISSN： 2193-5807

    eISSN： 2193-5815

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    Abstract Herein, we report the substitution reactions of para‐hydroxybenzyl alcohols catalyzed by the phosphazene base t‐Bu‐P2. This system is compatible with substrates bearing various functionalities, including alkyl, methoxy, thiophenyl, halogen, ester, and amide moieties. Thiols, 1,3‐dicarbonyl compounds, and amines can be used as nucleophiles. Mechanistically, the reaction proceeds via E1cB elimination of the benzylic hydroxyl group from the phenoxide intermediate to generate a para‐quinone methide intermediate, followed by nucleophilic 1,6‐addition.

  2. Carboxylations of (Hetero)Aromatic C–H Bonds Using an Alkyl Silyl Carbonate Reagent

    Kanta Shimotai, Ozora Sasamoto, Masanori Shigeno

    Organic Letters　2025/01/10

    DOI： 10.1021/acs.orglett.4c04388 　

    ISSN： 1523-7060 1523-7052

  3. Catalytic Concerted SNAr Reactions of Fluoroarenes by an Organic Superbase

    Masanori Shigeno, Kazutoshi Hayashi, Ozora Sasamoto, Riku Hirasawa, Toshinobu Korenaga, Shintaro Ishida, Kanako Nozawa-Kumada, Yoshinori Kondo

    Journal of the American Chemical Society　2024/11/08

    Publisher: American Chemical Society (ACS)

    DOI： 10.1021/jacs.4c09042 　

    ISSN： 0002-7863

    eISSN： 1520-5126

  4. LiO-t-Bu/CsF-Mediated Formal Hydrolysis of Trifluoromethyl Arenes

    Masanori Shigeno, Moe Kiriyama, Koki Izumi, Keita Sasaki, Ozora Sasamoto, Kanako Nozawa-Kumada, Yoshinori Kondo

    Synthesis　2023/12/28

    Publisher: Georg Thieme Verlag KG

    DOI： 10.1055/a-2236-0209 　

    ISSN： 0039-7881

    eISSN： 1437-210X

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    Abstract This study investigates the formal hydrolysis of trifluoromethyl arenes without deprotonation functionality utilizing a combined Brønsted base system comprising LiO-t-Bu and CsF. The reaction conditions were optimized using 4-(trifluoromethyl)biphenyl as the model substrate, achieving a 94% yield with LiO-t-Bu/CsF. The scope of the substrate was explored, demonstrating the applicability of the system to various functionalities, such as (hetero)aryl, tert-butyl, methyl, amide, and alkenyl moieties. Mechanistic insights suggest a single electron transfer process.

  5. Synthesis and characterization of tetraphenylammonium salts

    Hikaru Fujita, Ozora Sasamoto, Shiori Kobayashi, Masanori Kitamura, Munetaka Kunishima

    Nature Communications　2022/05/09

    DOI： 10.1038/s41467-022-30282-y 　

  6. Substitution of the Dimethylamino Group in Gramines and One-Pot Cyclization to Tetrahydro-β-carbolines Using a Triazine-Based Activating Agent. International-journal

    Hikaru Fujita, Riho Nishikawa, Ozora Sasamoto, Masanori Kitamura, Munetaka Kunishima

    The Journal of organic chemistry　84　(13)　8380-8391　2019/07/05

    DOI： 10.1021/acs.joc.9b00039 　

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    A new method for the substitution of 3-[(dimethylamino)methyl]indoles (gramines) with malonate-based nucleophiles was developed using 2-chloro-4,6-dimethoxy-1,3,5-triazine (CDMT) as the activating agent for the dimethylamino group. The reaction was completed in 1.5-6 h at room temperature in the presence of a tert-amine base and lithium salt. CDMT afforded superior results to methyl iodide, a common activating agent for the dimethylamino group in Mannich bases, particularly in the reactions of 1-substituted gramines. The reactivity of the possible intermediates, bis(indol-3-ylmethyl)dimethylammonium salts, was examined to obtain mechanistic insights on the reaction. This substitution method with CDMT enabled the sequential transformation of gramines: substitution with ( N-alkylidene)aminomalonates followed by the Pictet-Spengler reaction under acidic conditions afforded 1,2,3,4-tetrahydro-β-carboline derivatives in one pot.

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Presentations 14

  1. 炭素-酸素結合変換に基づくケミカルリサイクルを志向した芳香族ポリマーの開発

    笹本大空, 大坂京介, 林和寿, 田原淳士, 根東義則, 重野真徳

    第13回JACI/GSCシンポジウム

  2. 触媒的な炭素ー酸素結合変換を基盤とする分解性芳香族ポリマーの開発

    笹本大空, 大坂京介, 林和寿, 田原淳士, 根東義則, 重野真徳

    第35回万有仙台シンポジウム　2024/05/18

  3. Pd触媒を用いたB,N-ナフタレンの合成反応

    伊勢谷優仁, 久米遼太郎, 柳田瞭, 笹本大空, 根東義則, 重野真徳

    日本薬学会第144年会

  4. アルキルシリルカルボナートを活用した芳香族化合物の直截的カルボキシル化反応

    下平貫太, 笹本大空, 重野真徳

    日本薬学会第144年会

  5. 炭素-酸素結合変換に基づく分解性芳香族ポリマーの設計と触媒的な分解反応の開発

    笹本大空, 林和寿, 田原淳士, 根東義則, 重野真徳

    日本薬学会第144年会

  6. 炭素-酸素結合切断に基づく芳香族ポリマーの分解

    2023/12/09

  7. アルキルシリルカルボナートを用いる炭素-水素結合のカルボキシル化反応

    2023/12/09

  8. アルキルシリルカルボナートを用いたカルボキシル化反応の開発

  9. 分解性芳香族ポリマーの設計と合成

  10. 分解性芳香族ポリマーの設計

    2023/10/28

  11. アルキルシリルカルボナートを用いるカルボキシル化反応

    2023/10/28

  12. Carboxylation reaction using alkylsilyl carbonates

    ○Kanta Shimotai, Ozora Sasamoto, Masanori Shigeno

  13. Combined Brønsted base for hydrolysis of trifluoromethylarenes

    ○Moe Kiriyama, Koki Izumi, Keita Sasaki, Ozora Sasamoto, Masanori Shigeno, Yoshinori Kondo

    Tohoku University GP-Chem Chemistry Summer School 2023

  14. Dicarboxylations of allylbenzenes by a combined Brønsted base

    ○Eito Toyama, Kazuya Hanasaka, Ozora Sasamoto, Masanori Shigeno, Yoshinori Kondo

    Tohoku University GP-Chem Chemistry Summer School 2023

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Research Projects 3

  1. 有機超塩基触媒を用いた炭素－酸素結合切断を基軸とする分子変換反応の開発

    笹本 大空

    Offer Organization: 日本学術振興会

    System: 科学研究費助成事業

    Category: 研究活動スタート支援

    Institution: 東北大学

    2023/08/31 - 2025/03/31

  2. 密度汎関数理論に基づいた有機超塩基が示す 特異な反応性の理論的考察

    Offer Organization: 東北大学サイバーサイエンスセンター

    System: 令和5年度若手・女性研究者支援課題/学際大規模情報基盤共同利用・共同研究拠点（JHPCN）萌芽型共同研究課題

    2024/04 - 2025/03

  3. 有機超塩基触媒を基盤とする反応の機構解明

    笹本大空

    Offer Organization: 東北大学サイバーサイエンスセンター

    System: 令和5年度若手・女性研究者支援課題/学際大規模情報基盤共同利用・共同研究拠点（JHPCN）萌芽型共同研究課題

    2023/10 - 2024/03