Organization
School of Science Professor
Title
Professor
External link
OHMORI KEN
Degree
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博士（理学） ( 1996.3 慶應義塾大学 )
Papers
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Yoshio Ando, Daichi Ogawa, Shuichiro Morishita, Keisuke Suzuki, Ken Ohmori
Chemistry Letters 54 ( 11 ) 2025.10
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Facile synthetic route to isoxazoles from β-sulfinyl- and β-sulfonyl-cyclohexenones via regioselective nitrile oxide cycloaddition and in-situ elimination
Kazuki Murata, Keisuke Suzuki, Ken Ohmori
TETRAHEDRON LETTERS 151 2024.11
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Total Syntheses of β‐ and γ‐Naphthocyclinones
Yoshio Ando, Taiju Hoshino, Nozomi Tanaka, Mark M. Maturi, Yusuke Nakazawa, Takumi Fukazawa, Ken Ohmori, Keisuke Suzuki
Angewandte Chemie International Edition 64 ( 6 ) 2024.11
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Diastereoselective Access to anti -β-Hydroxy Sulfoxides from Chiral Epoxides and Prochiral Sulfenate Anions: Mechanistic Insights, Scope, and Limitation
Jian Zhang, Vipul V. Betkekar, Keisuke Suzuki, Ken Ohmori
SYNLETT 35 ( 12 ) 1458 - 1464 2024.7
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One-Pot Synthesis of Functionalized Benzotropones via a Phthalide Ring-Opening/Intramolecular Aldol Condensation Cascade
Sangeun Yeom, Ken Ohmori
ORGANIC LETTERS 26 ( 24 ) 5120 - 5124 2024.6
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Atomic-resolution structure analysis inside an adaptable porous framework
Yuki Wada, Pavel M. Usov, Bun Chan, Makoto Mukaida, Ken Ohmori, Yoshio Ando, Haruhiko Fuwa, Hiroyoshi Ohtsu, Masaki Kawano
Nature Communications 15 ( 1 ) 2024.1
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Total Syntheses of Sparsomycin and Sparoxomycins A1 and A2 via Sulfenate-Anion-Mediated Iterative C-S Bond Formation
Jian Zhang, Keisuke Suzuki, Ken Ohmori
ORGANIC LETTERS 25 ( 50 ) 9036 - 9040 2023.12
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Yoshio Ando, Keisuke Suzuki, Mark M. Maturi, Taiju Hoshino, Nozomi Tanaka, Takahiro Sakai, Ken Ohmori
Synlett 2023.7
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Yoshio Ando, Ken Ohmori, Daichi Ogawa, Fumihiro Wakita, Keisuke Suzuki
Synlett 35 ( 04 ) 441 - 444 2023.6
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Yoshio Ando, Daichi Ogawa, Ken Ohmori, Keisuke Suzuki
Angewandte Chemie International Edition 62 ( 5 ) 2022.12
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De novo synthesis of dimerization-ready flavan unit via intramolecular Pummerer/Friedel-Crafts cascade
Vipul V. Betkekar, Keisuke Suzuki, Ken Ohmori
ORGANIC & BIOMOLECULAR CHEMISTRY 20 ( 37 ) 7419 - 7423 2022.9
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Total Synthesis of Parameritannin A2, a Branched Epicatechin Tetramer with Two Double Linkages
Vipul V. Betkekar, Keisuke Suzuki, Ken Ohmori
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION 61 ( 28 ) 2022.7
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Total Syntheses of Spirooliganones A and B
Masao Morita, Nobuaki Nemoto, Ken Ohmori
Synlett 33 ( 06 ) 581 - 584 2022.3
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Total Synthesis and Structure Assignment of Saptomycin H Reviewed
Jun Shimura, Yoshio Ando, Ken Ohmori, Keisuke Suzuki
Organic Letters 24 ( 7 ) 1439 - 1443 2022.2
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Evaluation of amyloid polypeptide aggregation inhibition and disaggregation activity of a-type procyanidins
Taisei Tanaka, Vipul V. Betkekar, Ken Ohmori, Keisuke Suzuki, Hideyuki Shigemori
Pharmaceuticals 14 ( 11 ) 2021.11
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Ken Ohmori, Keisuke Suzuki, Seiya Matsuoka, Kohei Azami, Yusuke Fujiki, Reina Dohi, Tomokazu Yasuike
Synlett 32 ( 20 ) 2046 - 2052 2021.9
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Model Study toward Total Synthesis of Dimeric Pyranonaphthoquinones: Synthesis of Hemi-Actinorhodin Reviewed
Yoshio Ando, Takumi Fukazawa, Ken Ohmori, Keisuke Suzuki
Bulletin of the Chemical Society of Japan 94 ( 4 ) 1364 - 1376 2021.4
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Group-Selective Approaches to Complex Natural Product Synthesis: Three Examples of Diastereotopos-Selective Reactions
Ken Ohmori, Keisuke Suzuki
Synlett 33 ( 05 ) 429 - 439 2021
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Keisuke Suzuki, Hiroshi Nakakohara, Yoichi Hirano, Ken Ohmori, Hiroshi Takikawa
Synlett 32 ( 04 ) 423 - 428 2020.11
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Synthetic Study on Lactonamycins, Part 2: Stereoselective Access to ABCD-Ring System Reviewed
Hiroshi Takikawa, Kazuki Murata, Shogo Sato, Takuma Kawada, Hiroshi Nakakohara, Ken Ohmori, Keisuke Suzuki
Synlett 31 ( 16 ) 1623 - 1628 2020.10
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Thiolate-mediated Reductive Cyclizations: Scope, Limitation and Novel Mechanistic Insights Reviewed
Yoshio Ando, Takumi Fukazawa, Ken Ohmori, Keisuke Suzuki
Chemistry Letters 49 ( 9 ) 1103 - 1106 2020.9
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Synthesis of Enantiopure C<inf>2</inf>-Symmetric Anthracenophane and Dimerization en Route to Multiple-Bridged Cyclophanes Reviewed
Yasuyuki Ueda, Keisuke Suzuki, Ken Ohmori
Organic Letters 22 ( 5 ) 2002 - 2006 2020.3
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Intramolecular Benzyne–Phenolate [4+2] Cycloadditions Reviewed
Hiroshi Takikawa, Arata Nishii, Hiromu Takiguchi, Hirotoshi Yagishita, Masato Tanaka, Keiichi Hirano, Masanobu Uchiyama, Ken Ohmori, Keisuke Suzuki
Angewandte Chemie - International Edition 59 ( 30 ) 12440 - 12444 2020
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Thiolate-mediated reductive cyclization: asymmetric total synthesis of (+)-engelharquinone Reviewed
Yoshio Ando, Takumi Fukazawa, Subaru Hori, Ken Ohmori, Keisuke Suzuki
Phosphorus, Sulfur and Silicon and the Related Elements 194 ( 7 ) 723 - 725 2019.7
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Total Synthesis of Carthamin, a Traditional Natural Red Pigment Reviewed
Kohei Azami, Taiki Hayashi, Takenori Kusumi, Ken Ohmori, Keisuke Suzuki
Angewandte Chemie - International Edition 58 ( 16 ) 5321 - 5326 2019.4
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Total Synthesis of Actinorhodin Reviewed
Mamiko Ninomiya, Yoshio Ando, Fumitaka Kudo, Ken Ohmori, Keisuke Suzuki
Angewandte Chemie - International Edition 58 ( 13 ) 4264 - 4270 2019.3
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General Synthetic Approach to Rotenoids via Stereospecific, Group-Selective 1,2-Rearrangement and Dual S <inf>N</inf> Ar Cyclizations of Aryl Fluorides Reviewed
Seiya Matsuoka, Kayo Nakamura, Ken Ohmori, Keisuke Suzuki
Synthesis (Germany) 51 ( 5 ) 1139 - 1156 2019
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Syntheses of doubly linked proanthocyanidins using free flavan units as nucleophiles: Insight into the origin of the high regioselectivity of annulation Reviewed
Vipul V. Betkekar, Mio Harachi, Keisuke Suzuki, Ken Ohmori
Organic and Biomolecular Chemistry 17 ( 41 ) 9129 - 9134 2019
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Stereochemical Dichotomy in Two Competing Cascade Processes: Total Syntheses of Both Enantiomers of Spiroxin A Reviewed
Yoshio Ando, Daisuke Tanaka, Ryota Sasaki, Ken Ohmori, Keisuke Suzuki
Angewandte Chemie - International Edition 58 ( 36 ) 12507 - 12513 2019
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Synthesis of Oxygenated ortho-Methylbenzaldehydes via Aryne [2+2] Cycloaddition and Benzocyclobutenol Ring Opening Reviewed
Mark M. Maturi, Ken Ohmori, Keisuke Suzuki
CHIMIA vol. 72 ( No. 12 ) 870 - 873 2018.12
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Synthetic Studies on Flavan-Derived Natural Polyphenols: a Complex Molecular Platform in Organic Synthesis Reviewed
Ken OHMORI
Journal of Synthetic Organic Chemistry, Japan 76 ( 11 ) 1154 - 1162 2018.11
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Intramolecular photoredox reactions of 1,2-naphthoquinone derivatives Reviewed
Yoshio Ando, Fumihiro Wakita, Ken Ohmori, Keisuke Suzuki
Bioorganic and Medicinal Chemistry Letters 28 ( 16 ) 2663 - 2666 2018.9
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Model Reactions for the Enantioselective Synthesis of γ-Rubromycin: Stereospecific Intramolecular Photoredox Cyclization of an ortho-Quinone Ether to a Spiroacetal Reviewed
Fumihiro Wakita, Yoshio Ando, Ken Ohmori, Keisuke Suzuki
Organic Letters 20 ( 13 ) 3928 - 3932 2018.7
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Total Syntheses of Pusilatins A–C, Liverwort-Derived Macrocyclic Bisbibenzyl Dimers Reviewed
Takahiro Yamada, Hiromu Takiguchi, Ken Ohmori, Keisuke Suzuki
Organic Letters vol. 20 ( 12 ) 3579 - 3582 2018.6
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Total Synthesis of Selligueain A, a Sweet Flavan Trimer Reviewed
Yuka Noguchi, Rikako Takeda, Keisuke Suzuki, Ken Ohmori
Organic Letters vol. 20 ( 10 ) 2857 - 2861 2018.4
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First Total Synthesis of Oxirapentyn D, a Highly Oxidized Chromene Natural Product Reviewed
Takahiro Sakai, Keisuke Suzuki, Ken Ohmori
SYNLETT vol. 29 ( 10 ) 1351 - 1357 2018.4
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Impact of Green Tea Catechin ECG and Its Synthesized Fluorinated Analogue on Prostate Cancer Cells and Stimulated Immunocompetent Cells Reviewed
Sven Stadlbauer, Carmen Steinborn, Amy Klemd, Fumihiko Hattori, Ken Ohmori, Keisuke Suzuki, Roman Huber, Philipp Wolf, Carsten Gründemann
Planta Medica vol. 84 ( 11 ) 813 - 819 2018.2
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Stereospecificity in Intramolecular Photoredox ReactiStereospecificity in Intramolecular Photoredox Reactions of Naphthoquinones: Enantioselective Total Synthesis of (–)-Spiroxin C Reviewed
Yoshio Ando, Atsuko Hanaki, Ryota Sasaki, Ken OHMORI, KEISUKE SUZUKI
Angewandte Chemie - International Edition Vol. 56 ( 38 ) 11460 - 11465 2017.8
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Total Syntheses of Atrovenetin and Atrovenetinone: A Naphthalene Annulation Approach to a Discoid Tricycle using Allenic Acid Reviewed
Kyohei Matsushita, Ken Ohmori, Keisuke Suzuki
Synlett Vol. 28 ( 8 ) 944 - 950 2017.6
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Enantioselective Access to Bicyclo[3.2.1]octadienone Skeleton: Total Syntheses of (+)-Engelharquinone and Its Epoxide Reviewed
Takumi Fukazawa, Yoshio Ando, Ken OHMORI, KEISUKE SUZUKI
Organic Letters Vol. 19 ( 6 ) 1470 - 1473 2017.3
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Synthetic Study on Carthamin. 2. Stereoselective Approach to C-Glycosyl Quinochalcone via Desymmetrization Reviewed
Taiki Hayashi, Ken Ohmori, Keisuke Suzuki
Organic Letters vol. 19 ( 4 ) 866 - 869 2017.2
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Stereocontrolled Total Syntheses of (–)-Rotenone and (–)-Dalpanol by 1,2-Rearrangement and SNAr Oxycyclizations Reviewed
Kayo Nakamura, Ken OHMORI, KEISUKE SUZUKI
Angewandte Chemie International Edition Vol. 56 ( No. 1 ) 182 - 187 2016.12
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Total Synthesis of the Proposed Structure of Ardimerin, and Proposal for its Structural Revision Reviewed
Ryota Nakayama, Eva-Maria Tanzer, Ken Ohmori, Keisuke Suzuki
Helvetica Chimica Acta Vol. ( No. ) 944 - 960 2016.9
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Total Synthesis of (+)-Vicenin-2. Reviewed
Thanh C. Ho, HARUKI KAMIMURA, Ken Ohmori, Keisuke Suzuki
Organic Letters Vol. 18 ( No. 18 ) 4488 - 4490 2016.8
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Synthetic Study on Carthamin: Problem and Solution for Oxidative Dearomatization Approach to Quinol C-Glycoside Reviewed
Taiki Hayashi, Ken Ohmori, Keisuke Suzuki
SYNLETT 27 ( 16 ) 2345 - 2351 2016.7
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Stereocontrolled synthesis of planar chiral carba-paracyclophanes via modular assembly Reviewed
Sunna Jung, Yoko Kitajima, Yasuyuki Ueda, Keisuke Suzuki, Ken Ohmori
Synlett 27 ( 10 ) 1521 - 1526 2016.6
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Facile Synthesis of Stereodefined a-Iodovinyl Sulfides, Versatile Platform to Trisubstituted Olefins Reviewed
Sunna Jung, Yasuyuki Ueda, Keisuke Suzuki, Ken Ohmori
SYNLETT 27 ( 13 ) 2024 - 2028 2016.6
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Total Syntheses of Perenniporides Reviewed
Masao Morita, Ken Ohmori, Keisuke Suzuki
Organic Letters 17 (22) ( 22 ) 5634 - 5637 2015.11
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Procyanidins Negatively Affect the Activity of the Phosphatases of Regenerating Liver Reviewed
Sven Stadlbauer, Pablo Rios, Ken Ohmori, Keisuke Suzuki, Maja Köhn
PLOS ONE 10 ( 7 ) 2015.7
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Synthetic Study on Naphthospironone A: Construction of Benzobicyclo[3.2.1]octene Skeleton with Oxaspirocycle Reviewed
Juri Sakata, Yoshio Ando, Ken Ohmori, Keisuke Suzuki
Organic Letters 17 (15) ( 15 ) 3746 - 3749 2015.7
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Toward Naphthocyclinones: Doubly Connected Octaketide Dimers with a Bicyclo[3.2.1]octadienone Core by Thiolate-Mediated Cyclization Reviewed
Yoshio Ando, Subaru Hori, Takumi Fukazawa, Ken Ohmori, Keisuke Suzuki
Angewandte Chemie International Edition Vol. 54 ( 33 ) 9650 - 9653 2015.6
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Dioxanone-Fused Dienes Enable Highly Endo-Selective Intramolecular Diels–Alder Reactions Reviewed
Yoshifumi Aoki, Ken Ohmori, Keisuke Suzuki
Organic Letters 17 (11) ( 11 ) 2756 - 2759 2015.5
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The flavan–isoflavan rearrangement: bioinspired synthetic access to isoflavonoids via 1,2-shift–alkylation sequence Reviewed
Kayo Nakamura, Ken Ohmori, Keisuke Suzuk
Chemical Communications 51 ( 32 ) 7012 - 7014 2015.3
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Ambipolar Transistor Properties of 2,2′-Binaphthosemiquinones Reviewed
Toshiki Higashino, Kumeta Shouhei, Sumika Tamura, Yoshio Ando, Ken OHMORI, KEISUKE SUZUKI, Takehiko Mori
J. Mater. Chem. C Vol. 3 ( 7 ) 1588 - 1594 2014.12
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A seco-catechin cyclization approach to 4→6-linked catechin dimers Reviewed
Watanabe, G., Ken OHMORI, Suzuki, K.
Chemical Communications 50 ( 92 ) 14371 - 14373 2014.10
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Annulation approach to doubly linked (A-type) oligocatechins: Syntheses of (+)-procyanidin A2 and (+)-cinnamtannin B1 Reviewed
Ito, Y., Ken OHMORI, Suzuki, K.
Angewandte Chemie - International Edition 53 ( 38 ) 10129 - 10133 2014.9
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Synthetic Strategies and Tactics for Catechin and Related Polyphenols Reviewed
Ken OHMORI, Suzuki, K.
Recent Advances in Polyphenol Research 4 371 - 410 2014.8
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Synthesis and determination of the absolute configuration of cavicularin by a symmetrization/asymmetrization approach Reviewed
Takiguchi, H., Ken OHMORI, Suzuki, K.
Angewandte Chemie - International Edition 52 ( 40 ) 10472 - 10476 2013.9
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First regiocontrolled synthesis of procyanidin B6, a catechin dimer with rare connectivity: A halo-capping strategy for formation of 4,6-interflavan bonds Reviewed
Watanabe, G., Ken OHMORI, Suzuki, K.
Chemical Communications 49 ( 45 ) 5210 - 5212 2013.5
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Synthesis and structure revision of goupiolone A: A benzotropolone natural product Reviewed
Fukui, N., Ken OHMORI, Suzuki, K.
Helvetica Chimica Acta 95 ( 11 ) 2194 - 2217 2012.11
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Unified approach to catechin hetero-oligomers: First total synthesis of trimer EZ-EG-CA isolated from Ziziphus jujuba Reviewed
Yano, T., Ken OHMORI, Takahashi, H., Takenori Kusumi, Suzuki, K.
Organic and Biomolecular Chemistry 10 ( 38 ) 7685 - 7688 2012.10
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A new synthetic strategy for catechin-class polyphenols: Concise synthesis of (-)-epicatechin and its 3-O-gallate Reviewed
Stadlbauer, S., Ken OHMORI, Hattori, F., Suzuki, K.
Chemical Communications 48 ( 67 ) 8425 - 8427 2012.7
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Synthetic strategies and tactics for oligomeric proanthocyanidins Reviewed
Ken OHMORI, Suzuki, K.
Current Organic Chemistry 16 ( 5 ) 566 - 577 2012.3
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Ring Expansion of Cyclopropylbenzocyclobutenes En Route to Benzocycloheptenes Reviewed
Fukui, Nobuaki, Hamura, Toshiyuki, Ken OHMORI, Suzuki, Keisuke
CHEMISTRY LETTERS 40 ( 10 ) 1198 - 1200 2011.10
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Synthetic challenge to ubiquitous natural products from plant origin: Flavan-derived polyphenols Reviewed
Ken OHMORI
Chemical Record 11 ( 5 ) 252 - 259 2011.9
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Integrated synthetic strategy for higher catechin oligomers Reviewed
Ken OHMORI, Shono, T., Hatakoshi, Y., Yano, T., Suzuki, K.
Angewandte Chemie - International Edition 50 ( 21 ) 4862 - 4867 2011.5
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Regioselective approach to multisubstituted benzenes Reviewed
Seo, H., Ken OHMORI, Suzuki, K.
Chemistry Letters 40 ( 7 ) 744 - 746 2011
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Concise synthesis of riccardin C, macrocyclic bisbibenzyl natural product Reviewed
Takiguchi, H., Ken OHMORI, Suzuki, K.
Chemistry Letters Vol. 40 ( No. 10 ) 1069 - 1071 2011
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Ring expansion approach to azaspiro[4.5]decane skeletons via electrophilic activation of benzocyclobutenols bearing pyridyl group Reviewed
Hayashi, T., Ken OHMORI, Suzuki, K.
Chemistry Letters 40 ( 6 ) 612 - 613 2011
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Expeditious modular assembly of multisubstituted cyclohexanes via dioxanonedienes Reviewed
Aoki, Y., Mochizuki, Y., Yoshinari, T., Ken OHMORI, Suzuki, K.
Chemistry Letters 40 ( 10 ) 1192 - 1194 2011
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General synthesis of epi-series catechins and their 3-gallates: Reverse polarity strategy Reviewed
Ken Ohmori, Takahisa Yano, Keisuke Suzuki
Organic and Biomolecular Chemistry 8 ( 12 ) 2693 - 2696 2010.6
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Lecture Tour upon Receiving the 5th Merck-Banyu Lectureship Award (MBLA2008) Reviewed
Ken Ohmori
Yuki Gosei Kagaku Kyokaishi/Journal of Synthetic Organic Chemistry 68 ( 4 ) 411 - 418 2010.4
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Synthesis and chiroptical properties of π-conjugated polymer consisting of dihydropentahelicene units with axial chirality Reviewed
Masahiro Abe, Ken Ohmori, Keisuke Suzuki, Takakazu Yamamoto
Journal of Polymer Science, Part A: Polymer Chemistry 48 ( 8 ) 1844 - 1848 2010.4
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Total Synthesis and Absolute Configuration of Macrocidin A, a Cyclophane Tetramic Acid Natural Product Reviewed
Ken OHMORI
Angew. Chem. Int. Ed. Vol. 49 ( 5 ) 881 - 885 2010.1
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Anti-selective vinylogous aldol reaction by silylated alkyldioxinone dienolate Reviewed
Tomohiro Yoshinari, Ken Ohmori, Keisuke Suzuki
Chemistry Letters 39 ( 10 ) 1042 - 1044 2010
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Hydrogen-bond control in axially chiral styrenes: Selective synthesis of enantiomerically pure c<inf>2</inf>-symmetric paracyclophanes Reviewed
Keiji Mori, Ken Ohmori, Keisuke Suzuki
Angewandte Chemie - International Edition 48 ( 31 ) 5638 - 5641 2009.7
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Stereochemical relay via axially chiral styrenes: Asymmetric synthesis of the antibiotic tan-1085 Reviewed
Keiji Mori, Ken Ohmori, Keisuke Suzuki
Angewandte Chemie - International Edition 48 ( 31 ) 5633 - 5637 2009.7
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First stereoselective total synthesis of FD-594 aglycon Reviewed
Ritsuki Masuo, Ken Ohmori, Lukas Hintermann, Saki Yoshida, Keisuke Suzuki
Angewandte Chemie - International Edition 48 ( 19 ) 3462 - 3465 2009.4
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Stereocontolled synthesis of (-)-afzelechin: General route to catechin-class polyphenols by solving an S <inf>N</inf>2 vs. S <inf>N</inf>1 problem Reviewed
Ken Ohmori, Megumi Takeda, Takashi Higuchi, Tomohiro Shono, Keisuke Suzuki
Chemistry Letters 38 ( 9 ) 934 - 935 2009
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Synthesis and stereochemical assignment of angucycline antibiotic, PD-116740 Reviewed
Keiji Mori, Yuuya Tanaka, Ken Ohmori, Keisuke Suzuki
Chemistry Letters 37 ( 4 ) 470 - 471 2008.4
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27 The Asymmetric Total Synthesis of TAN-1085
Mori Keiji, Ohmori Ken, Suzuki Keisuke
Symposium on the Chemistry of Natural Products, symposium papers ( 49 ) 157 - 162 2007.8
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Stereoselective access to functionalized dihydrophenanthrenes via reductive cyclization of biaryl ene-aldehydes Reviewed
Minoru Tamiya, Corinna Jager, Ken Ohmori, Keisuke Suzuki
Synlett ( 5 ) 780 - 784 2007.3
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Two isolable conformers of dihydropentahelicenediol derivatives: Stereochemical property and its utility for asymmetric reactions Reviewed
Ken Ohmori, Sanae Furuya, Shigeo Yamanoi, Keisuke Suzuki
Chemistry Letters 36 ( 2 ) 328 - 329 2007.2
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General synthesis route to benanomicin-pradimicin antibiotics Reviewed
Minora Tamiya, Ken Ohmori, Mitsuru Kitamura, Hirohisa Kato, Tadamasa Arai, Mami Oorui, Keisuke Suzuki
Chemistry - A European Journal 13 ( 35 ) 9791 - 9823 2007
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General and convenient approach to flavan-3-ols: Stereoselective synthesis of (-)-gallocatechin Reviewed
Takashi Higuchi, Ken Ohmori, Keisuke Suzuki
Chemistry Letters 35 ( 9 ) 1006 - 1007 2006.9
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P-245 Axially Chiral Styrene : Key for the Asymmetric Total Synthesis of TAN-1085
Mori Keiji, Ohmori Ken, Suzuki Keisuke
International Symposium on the Chemistry of Natural Products 2006 "P - 245" 2006.7
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天然物化学ー植物編 Reviewed
大森建, 鈴木啓介, 長谷川宏司
2006
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Regio- and stereocontrolled total synthesis of benanomicin B Reviewed
Ken Ohmori, Minoru Tamiya, Mitsuru Kitamura, Hirohisa Kato, Mami Oorui, Keisuke Suzuki
Angewandte Chemie - International Edition 44 ( 25 ) 3871 - 3874 2005.6
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Synthesis of (±)-lotthanongine, a novel natural product with a flavan-indole hybrid structure Reviewed
Keisuke Hatakeyama, Ken Ohmori, Keisuke Suzuki
Synlett ( 8 ) 1311 - 1315 2005.5
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Oligomeric catechins: An enabling synthetic strategy by orthogonal activation and C(8) protection Reviewed
Ken Ohmori, Naoko Ushimaru, Keisuke Suzuki
Proceedings of the National Academy of Sciences of the United States of America 101 ( 33 ) 12002 - 12007 2004.8
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Concise total synthesis and structure assignment of TAN-1085 Reviewed
Ken Ohmori, Keiji Mon, Yuji Ishikawa, Hideyuki Tsuruta, Shunsuke Kuwahara, Nobuyuki Harada, Keisuke Suzuki
Angewandte Chemie - International Edition 43 ( 24 ) 3167 - 3171 2004.6
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Cationic zirconocene- or hafnocene-based Lewis acids in organic synthesis: Glycoside-flavonoid analogy Reviewed
Ken Ohmori, Keisuke Hatakeyama, Hiroki Ohrui, Keisuke Suzuki
Tetrahedron 60 ( 6 ) 1365 - 1373 2004.2
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Evolution of synthetic strategies for highly functionalized natural products: A successful route to bryostatin 3 Reviewed
Ken Ohmori
Bulletin of the Chemical Society of Japan 77 ( 5 ) 875 - 885 2004
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38 Total Synthesis of TAN-1085
OHMORI Ken, ISHIKAWA Yuji, MORI Keiji, TSURUTA Hideyuki, SUZUKI Keisuke
Symposium on the Chemistry of Natural Products, symposium papers ( 45 ) 221 - 226 2003.9
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Stereoselective substitution of flavan skeletons: Synthesis of dryopteric acid Reviewed
Ken Ohmori, Naoko Ushimaru, Keisuke Suzuki
Tetrahedron Letters 43 ( 43 ) 7753 - 7756 2002.10
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Semi-pinacol strategy for constructing B-ring of pradimicin-benanomicin antibiotics Reviewed
Ken Ohmori, Mitsuru Kitamura, Yuji Ishikawa, Hirohisa Kato, Mami Oorui, Keisuke Suzuki
Tetrahedron Letters 43 ( 39 ) 7023 - 7026 2002.9
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Stereogenic tert-alcohols via group-selective hydroalumination: Further scope Reviewed
Ken Ohmori, Yoshifumi Hachisu, Takao Suzuki, Keisuke Suzuki
Tetrahedron Letters 43 ( 6 ) 1031 - 1034 2002.2
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Pseudo-C<inf>3</inf>-Symmetric Tertiary Alcohol Building Block via Group-Selective Hydroalumination: A Synthesis of (-)-Malyngolide Reviewed
Takao Suzuki, Ken Ohmori, Keisuke Suzuki
Organic Letters 3 ( 11 ) 1741 - 1744 2001.5
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Group-selective hydroalumination: A novel route to stereogenic tert-alcohol centers Reviewed
Ken Ohmori, Takao Suzuki, Kimiko Taya, Daisuke Tanabe, Toshihiro Ohta, Keisuke Suzuki
Organic Letters 3 ( 7 ) 1057 - 1060 2001.4
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Convenient procedure for one-pot conversion of azides to N-monomethylamines Reviewed
H. Kato, K. Ohmori, K. Suzuki
Synlett ( SPEC. ISS ) 1003 - 1005 2001
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Glycosylation study on pradimicin-benanomicin antibiotics Reviewed
H. Kato, K. Ohmori, K. Suzuki
Tetrahedron Letters 41 ( 35 ) 6827 - 6832 2000.8
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First synthesis of astilbin, biologically active glycosyl flavonoid isolated from Chinese folk medicine Reviewed
Ken Ohmori, Hiroki Ohrui, Keisuke Suzuki
Tetrahedron Letters 41 ( 29 ) 5537 - 5541 2000.7
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Total synthesis of bryostatin 3 Reviewed
Ken Ohmori, Yasuyuki Ogawa, Tetsuo Obitsu, Yuichi Ishikawa, Shigeru Nishiyama, Shosuke Yamamura
Angewandte Chemie - International Edition 39 ( 13 ) 2290 - 2294 2000.7
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Total synthesis of ravidomycin: Revision of absolute and relative stereochemistry Reviewed
Shin Futagami, Yoriko Ohashi, Koreaki Imura, Takamitsu Hosoya, Ken Ohmori, Takashi Matsumoto, Keisuke Suzuki
Tetrahedron Letters 41 ( 7 ) 1063 - 1067 2000.2
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(+)-3-{(4S,5S)-5-[1,1-dimethyl-2-(phenylthio)ethyl]-2,2-dimethyl-1,3-dioxolan-4-yl}prop-2-yn-1-ol Reviewed
Hiroyuki Hosomi, Shigeru Ohba, Ken Ohmori, Tetsuo Obitsu, Yasuyuki Ogawa, Yuichi Ishikawa, Shosuke Yamamura, Shigeru Nishiyama
Acta Crystallographica Section C: Crystal Structure Communications 56 ( 4 ) e142 - e143 2000
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Thermodynamic and kinetic properties of trans-3,4,5,6-tetramethyl-9,10- dihydroxy-9, 10-dihydrophenanthrene: Pseudo-rotational barriers around biphenyl axis Reviewed
Hirohisa Kato, Ken Ohmori, Keisuke Suzuki
Chirality 12 ( 5-6 ) 548 - 550 2000
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(-)-(3S)-4-(2-{[4,4-Dimethoxy-6-(benzyloxymethyl)perhydropyran-2-yl]methyl}-1,3-dithian-2-yl)-4-methyl-3-(1,1,2,2-tetramethyl-1-silapropoxy)- Pentan-1-ol Reviewed
Hiroyuki Hosomi, Shigeru Ohba, Ken Ohmori, Tetsuo Obitsu, Yasuyuki Ogawa, Yuichi Ishikawa, Shosuke Yamamura, Shigeru Nishiyama
Acta Crystallographica Section C: Crystal Structure Communications 56 ( 4 ) e140 - e141 2000
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Divergent behavior of cobalt-complexed enyne having a leaving group Reviewed
Mitsuru Kitamura, Ken Ohmori, Keisuke Suzuki
Tetrahedron Letters 40 ( 24 ) 4563 - 4566 1999.6
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Total synthesis of pradimicinone, the common aglycon of the pradimicin-benanomicin antibiotics Reviewed
Mitsuru Kitamura, Ken Ohmori, Toshihisa Kawase, Keisuke Suzuki
Angewandte Chemie - International Edition 38 ( 9 ) 1229 - 1232 1999.5
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From axial chirality to central chiralities: Pinacol cyclization of 2,2′-biaryldicarbaldehyde to trans-9,10-dihydrophenanthrene-9,10-diol Reviewed
Ken Ohmori, Mitsuru Kitamura, Keisuke Suzuki
Angewandte Chemie - International Edition 38 ( 9 ) 1226 - 1229 1999.5
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From Axial Chirality to Central Chiralities:Pinacol Cyclization of 2 2 1-Biaryldicarbaldehyde en route to trans-9 10-Dihydrophenathren-9 10-diol Substructure of Pradimicin-Benanomicin Antibiotics Reviewed
Ken Ohmori, Mitsuru Kitanura, Keisuke Suzuki
Angew. Chem. Int. Ed. Engl. 38 1999
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Synthesis of the C<inf>17</inf>-C<inf>27</inf> fragment of bryostatin 3 Reviewed
Tetsuo Obitsu, Ken Ohmori, Yasuyuki Ogawa, Hiroyuki Hosomi, Shigeru Ohba, Shigeru Nishiyama, Shosuke Yamamura
Tetrahedron Letters 39 ( 40 ) 7349 - 7352 1998.10
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31 Synthetic studies on bryostatins
Ohmori Ken, Obitsu Tetsuo, Ogawa Yasuyuki, Ishikawa Yuuichi, Nishiyama Shigeru, Yamamura Shosuke
Symposium on the Chemistry of Natural Products, symposium papers ( 40 ) 181 - 186 1998.8
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Chemical study on hapalosin, a cyclic depsipeptide possessing multidrug resistance reversing activities: Synthesis, structure and biological activity Reviewed
Toshiaki Okuno, Ken Ohmori, Shigeru Nishiyama, Shosuke Yamamura, Kensuke Nakamura, K. N. Houk, Kazuya Okamoto
Tetrahedron 52 ( 47 ) 14723 - 14734 1996.11
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Synthetic study on hapalosin, a cyclic depsipeptide possessing multidrug resistance reversing activities Reviewed
Ken Ohmori, Toshiaki Okuno, Shigeru Nishiyama, Shosuke Yamamura
Tetrahedron Letters 37 ( 20 ) 3467 - 3470 1996.5
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Synthetic studies on bryostatins, potent antineoplastic agents: Synthesis of the C<inf>17</inf>C<inf>27</inf> fragment of C<inf>20</inf> oxygenated bryostatins
Ken Ohmori, Shigeru Nishiyama, Shosuke Yamamura
Tetrahedron Letters 36 ( 36 ) 6519 - 6522 1995.9
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Synthetic studies on bryostatins, potent antineoplastic agents: Synthesis of the C<inf>17</inf>C;<inf>27</inf> fragment of C<inf>20</inf> deoxybryostatins Reviewed
Ken Ohmori, Takayuki Suzuki, Shigeru Nishiyama, Shosuke Yamamura
Tetrahedron Letters 36 ( 36 ) 6515 - 6518 1995.9
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Keiko Mochizuki, Ken Ohmori, Harumi Tamura, Yoshikazu Shizuri, Shigeru Nishiyama, Eiichi Miyoshi, Shosuke Yamamura
Bulletin of the Chemical Society of Japan 66 ( 10 ) 3041 - 3046 1993.10
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Synthetic studies on bryostatins, antineoplastic metabolites: Convergent synthesis of the C<inf>1</inf>-C<inf>16</inf> fragment shared by all of the bryostatin family Reviewed
Ken Ohmori, Takayuki Suzuki, Kazuyuki Miyazawa, Shigeru Nishiyama, Shosuke Yamamura
Tetrahedron Letters 34 ( 31 ) 4981 - 4984 1993.7
MISC
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大森 建
化学と工業 = Chemistry and chemical industry 62 ( 2 ) 142 - 145 2009.2
Research Projects
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有機合成によるデザイン分子の実空間機能・構造パターン検証
Grant number：23H04888 2023.4 - 2028.3
日本学術振興会 科学研究費助成事業 学術変革領域研究(A)
大森 建, 塚野 千尋
Grant amount：\125450000 （ Direct Cost: \96500000 、 Indirect Cost：\28950000 ）
本年度の研究では、1) 特異な連結様式を有するフラバン二量体の合成研究、2)多環芳香族ポリケチド抗生物質の合成研究、3)マイクロフロー法を利用した直鎖型フラバンオリゴマーの効率的合成技術の開発の３点に関し、集中的に検討を進め、ケミカルスペースの拡充を推進した。まず、1)の検討に関しては、前年度にて検討済みのフラバン骨格４位同士の連結方法を適用し、実際に特異な連結様式を有するフラバン２量体であるアビサノールAの合成を行った。モデルとして行ったフラバン単位の二量化実験では、反応点に隣接する位置にある水酸基に特定の保護基を導入すると、カップリング時の立体選択性が向上することを見出した。また実際の天然物の合成に必要な稀少フラバン単位であるアフゼレキンの合成法に関して検討を行った結果、従来、市販化合物から11工程（総収率19％）必要であった合成を、僅か３工程（総収率36％）まで短縮することに成功した。そして、その知見を活かし最終的にアビサノールAの全合成に成功した。2)の検討に関しては、多くのアントラキノン系天然物に共通する骨格の、効率的構築法を見出すことができた。さらにそれらに対する新奇のビシクロ環形成法を見出し、複雑な多環系を構築する手法を見出した。3)の検討に関しては、マイクロミキサを用いたフラバン単位の効率的なオリゴマー化について詳細な条件検討を行い、高収率で活性型多量体を合成することに成功した。
一方、研究分担者（塚野）は、プロテインキナーゼC（PKC）の活性化作用を有する化合物の創製を目指して、機械学習を基盤とした新規骨格の設計、合成と生物活性評価を実施した。本年度はアロタケタール類からの構造の単純化とPKC活性化作用が期待されるジテルペンの合成に取り組んだ。 -
天然物が織り成す化合物潜在空間が拓く生物活性分子デザイン
Grant number：23H04880 2023.4 - 2028.3
日本学術振興会 科学研究費助成事業 学術変革領域研究(A)
菊地 和也, 榊原 康文, 伊藤 寛晃, 丹羽 節, 荒井 緑, 大森 建, 大上 雅史, 上田 実, 鎌田 真由美, 吉田 稔
Grant amount：\123630000 （ Direct Cost: \95100000 、 Indirect Cost：\28530000 ）
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可逆的な分子連結反応を鍵とする新規インターロック分子の設計と合成
Grant number：21K18950 2021.7 - 2024.3
日本学術振興会 科学研究費助成事業 挑戦的研究(萌芽)
大森 建
Grant amount：\6370000 （ Direct Cost: \4900000 、 Indirect Cost：\1470000 ）
本年度の研究においては、共有結合形成を基盤とした堅牢かつ柔軟なインターロック分子の合成経路を開拓するため、まずその基本となる「in-cyclophane」構造（官能基が環の内側を向いたシクロファン構造）のプラットホームとして、アントラセン誘導体の合成経路の開拓を行った。
はじめに1,5-ジブロモアントラセン酸誘導体と、9-bromonon-1-eneのヒドロホウ素化により調製したボランを用いた鈴木ー宮浦カップリング反応を行い対応するジエン誘導体を得た後、第一世代および第二世代のGrubbs触媒を用いたring closing olefin metathesis（RCM）による架橋鎖の構築を試みたが、不首尾に終わった。
種々検討の結果、1,5-ジブロモアントラセン誘導体とアルキン（7-octyn-1-ol）を用いた薗頭反応にて調製したビスアルキニルアントラセン誘導体が目的とするシクロファン単位の合成前駆体となることを見出した。具体的には、シス選択的な炭素-炭素三重結合の半還元およびアルコール部の酸化、Wittig反応および、続く第一世代のGrubbs触媒を用いたring closing olefin metathesis（RCM）反応により架橋鎖を構築し、目的とするアントラセノファン構造の簡便な合成経路の開拓に成功した。
さらに本研究においては合成したアントラセノファン誘導体の反応性を調べた。まず、TCNE（テトラシアノエチレン）とのDielsーAlder反応および逆DielsーAlder反応を試みたところ、期待した可逆的付加環化反応性を示すことが分った。さらに、アントラセノファン誘導体の二量化反応および逆二量化反応を光および熱的条件下で行ったところ、優れた可逆性が示された。また架橋鎖導入の検討の途上、スルフェートアニオンのオキシラン環に対する予期せぬ反応性を発見した。 -
ポリフェノール構造をプラットホームとする新規化合物空間の構築と機能開拓
Grant number：21H04703 2021.4 - 2026.3
日本学術振興会 科学研究費助成事業 基盤研究(A)
大森 建
Grant amount：\41990000 （ Direct Cost: \32300000 、 Indirect Cost：\9690000 ）
本年度の研究においては、１）フラボノイドオリゴマーの合成に必要なモノマー単位の効率合成法の開発、２）複雑な分岐構造をもつ二重連結型フラバンオリゴマー、parameritannin A2の全合成研究、３）剛直な大環状構造を有するクラウンプロシアニジン類の全合成研究、４）マイクロフローミキサを用いた、直鎖型フラバンオリゴマーの効率的合成技術の開発の４点に関し、集中的に検討を進めた。
まず、１）の検討に関しては、フラバン骨格中のフェノール性水酸基が異なる保護基により区別された誘導体の効率的な合成経路の開拓を行った結果、光学活性なグリシドールを出発化合物とした簡便かつ効率的な合成経路を確立することができた。次に２）に関しては、フロログルシノールとジオキシ基を有するフラバンモノマーを１：２の比で反応させ、一挙に２つの二重連結構造を構築する方法を見出した。さらにPummerer反応とFriedel-Crafts反応のカスケードプロセスによる新規フラバン骨格構築法を開発し、parameritannin A2の初の全合成に成功した。一方、３）の検討に関しては、一般に形成が難しい、フラバン単位の４位と６位間の連結を可能とする手法を見出した。具体的には、求核成分として用いるフラバン単位のＡ環部（ベンゼン環部）のフェノール性水酸基を無保護としたうえで、副反応を抑えるために同ベンゼン環部の8位に塩素原子を導入した（8位をクロロキャップした）フラバン誘導体を用いると、望む位置でのみ反応を進行させることができることを見出した。そして４）の検討に関しては、従来のフラスコを用いたバッチ反応に比べ、より効率的なマイクロミキサを用いたフロー法に基づくオリゴマー化技術の開発に成功し、新技術として特許を出願した。 -
Synthesis and development of densely functionalized meddle-size flavonoids
Grant number：18H04391 2018.4 - 2020.3
Japan Society for the Promotion of Science Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research on Innovative Areas (Research in a proposed research area) Grant-in-Aid for Scientific Research on Innovative Areas (Research in a proposed research area)
Grant amount：\4680000 （ Direct Cost: \3600000 、 Indirect Cost：\1080000 ）
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Studies on Chemical Synthesis of Polyketide-Derived, Biologically Active Complex Natural Products
Grant number：16H06351 2016.5 - 2021.3
Japan Society for the Promotion of Science Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (S) Grant-in-Aid for Scientific Research (S)
Suzuki Keisuke
Grant amount：\184340000 （ Direct Cost: \141800000 、 Indirect Cost：\42540000 ）
The project on “Studies on Chemical Synthesis of Polyketide-Derived, Biologically Active Complex Natural Products” has been performed at the total synthesis of various complex natural products derived from type-II polyketide biosynthesis. Particular focus was laid on the natural process of evolving the structure diversity and complexity, trying to gain inspiration in developing new synthetic strategies and tactics in organic synthesis. More specifically, we focused three biosynthetic processes by which molecular complexity is enhanced, 1) oxidative structure modification, 2) oligomerization, and 3) hybridization, and aimed at the realization of these complexity/diversity-generating processes in chemical synthesis. Throughout the five-year research, we have succeeded in developing several synthetic routes to some useful/interesting classes of bioactive molecules.
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Controlled Synthesis and Development of Higher-order Functional Biomass Polyphenols
Grant number：16H04107 2016.4 - 2019.3
Japan Society for the Promotion of Science Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B) Grant-in-Aid for Scientific Research (B)
Ohmori Ken, Suzuki Keisuke, Misaka Takumi
Grant amount：\17030000 （ Direct Cost: \13100000 、 Indirect Cost：\3930000 ）
Although natural polyphenols have long played a part in human life as ingredients of wine, tea, or herbal medicines, it was only recently that their biological functions have been unveiled at the molecular level. The realization that specific interactions of polyphenols with biomolecules, such as proteins, exert powerful biological activities has stimulated the search for new pharmaceutical entities derived from polyphenolic entities. These investigations, however, are often hampered by the difficulty in isolating the requisite compounds in pure and structurally defined form, largely because their procurement has relied on natural sources, e.g., plant extracts. This study successfully offers one of synthetic solutions to provide such compounds, in particular, doubly-linked oligomeric flavans. The present study is based on an orthogonal synthetic strategy coupled with an annulation method, enabling efficient accesses to various types of flavan oligomers.
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フラボノイドを合成モジュールとした集積ポリフェノール構造の構築と機能開拓
Grant number：16H01137 2016.4 - 2018.3
日本学術振興会 科学研究費助成事業 新学術領域研究(研究領域提案型) 新学術領域研究(研究領域提案型)
大森 建
Grant amount：\5720000 （ Direct Cost: \4400000 、 Indirect Cost：\1320000 ）
ポリフェノールは、植物全般に豊富に含まれる天然有機成分であり、古来より染料や鞣皮料あるいは健康薬等として、広く利用されてきた。そのため有用生理活性物質の宝庫と期待されるが、天然から高純度の化合物を得ることが難しいため、個々の化学的性質が明らかにされた例は限られている。このような背景の下、本研究においては、天然から入手困難なフラボノイド系ポリフェノールを合成により構造が定まった単一化合物として得、それらの化学的諸性質の理解を通じ、未知であるポリフェノールと生体高分子との相互作用の解明や新機能の発見に寄与することを目指す。当研究事業の最終年度である本年度においては、次の課題に取り組み成果を得た。まず、これまでの研究により確立したフラボノイドのde novo 合成法を活かし、希少フラボノイドの一つであるアフゼレキンおよびエピアフゼレキン誘導体の合成を行った。そして合成したそれらフラバン単位を本研究で開発したアヌレーション法とオルトゴナル法を用い、順次結合させることにより、甘味を呈するフラバン三量体、Selligueain Aの初の効率全合成に成功した。また、得られた知見をもとにさらに合成難度の高いフラバン４量体の合成を試みた結果、その基本オリゴマー構造を構築するための基本合成技術を開拓することができた。本法の鍵は、フラバン骨格にジチオ基を導入することにより、オルトゴナルアヌレーションを可能とした点にある。本法は、集積二重連結型フラバンオリゴマーの一般的合成法となり得る信頼性の高い方法であり、今後、様々な誘導体の合成に応用可能と期待される。
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Synthetic study on planar-chiral compounds and its dynamic behavior on their ratchet structures
Grant number：15K13690 2015.4 - 2018.3
Japan Society for the Promotion of Science Grants-in-Aid for Scientific Research Grant-in-Aid for Challenging Exploratory Research Grant-in-Aid for Challenging Exploratory Research
Ohmori Ken
Grant amount：\3900000 （ Direct Cost: \3000000 、 Indirect Cost：\900000 ）
Syntheses of planar planar-chiral cyclophane derivatives and their stereochemical property was studied by exploiting the orthogonal Suzuki-Miyaura coupling strategy by using a selectively-protected phenyldiboronic acid derivative and planar-chral carba-paracyclophane units. This method enabled efficient assembly of various heptaphenylene derivatives incorporating non-substituted phenylene spacers. circular dichroism (CD) spectra of these oligophenylenes show characteristic CD curve patterns, suggesting a helical conformation on their oligophenylene axis.
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Development of Efficient Synthetic Transformation based on Intramolecular Redox Reaction
Grant number：24350021 2012.4 - 2016.3
Japan Society for the Promotion of Science Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)
Ohmori Ken, SUZUKI Keisuke, ANDO Yoshio
Grant amount：\18330000 （ Direct Cost: \14100000 、 Indirect Cost：\4230000 ）
This research project focused on development of new synthetic strategy and tactics focusing on intra-molecular redox transformations. Three research topics are addressed. At first, retro-[4+2] cycloaddition reaction for enolsilyl ether of dioxinone derivative was studied. The planned reaction proved feasible by heating of the substrate in toluene or xylene, giving the corresponding allene derivatives in moderate to high yield. In second, reaction of allenes and nitrones were studied. Upon heating of the allenes with nitrones underwent unusual homolytic N-O bond cleavage followed by recombination of resulting radicals to form a C-C bond, affording the corresponding lactams albeit in low yields. This research has been also studied intramolecular redox reaction of naphthoquinone derivatives, enabling construction of a new heterocyclic ring, typically furan ring skeletons. This method would serve as an efficient way to synthesize various polycyclic compounds.
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Studies on the Synthesis of Highly Oxidized Complex Natural Products of Biological Significance
Grant number：23000006 2011 - 2015
Japan Society for the Promotion of Science Grants-in-Aid for Scientific Research Grant-in-Aid for Specially Promoted Research Grant-in-Aid for Specially Promoted Research
SUZUKI Keisuke, OHMORI Ken, ANDO Yoshio, TAKIKAWA Hiroshi, TAKAHASHI Haruko, MATSUMOTO Takashi, KUSUMI Takenori
Grant amount：\433940000 （ Direct Cost: \333800000 、 Indirect Cost：\100140000 ）
The project has dealt with the total synthesis of highly oxidized complex natural products, including (1) polyketides, (2) polyphenols, and (3) glycoconjugates with polycyclic structures. Subject 1 exploited isoxazole as a platform for stereo-controlled dimerization of anthraquinone and installation of angular cis-diol, enabling total syntheses of BE-43472B, pleospdione, and tetracenomycin C. Study on the pyranonaphthoquinone dimers led to the development of unusual dimerization protocols, enabling the first total synthesis of actinorhodin and a promising access to naphthocylines via thiolate-mediated dimerization protocol. Subject 2 was associated with synthesis of the catechin oligomers. Based on the concept of catechin–sugar analogy as well as the orthogonal activation, effective approaches have been established for synthesizing the linear as well as doubly-connected oligomers. Subject 3 dealt with the synthesis of bis-aryl C-glycoside antibiotics, and the first total synthesis of saptomycin B has been accomplished, enabling assignment of the C14-stereochmistry.
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Stereoselective synthesis and higher-order derivatization of planar chiral cyclophanes
Grant number：23655031 2011 - 2012
Japan Society for the Promotion of Science Grants-in-Aid for Scientific Research Grant-in-Aid for Challenging Exploratory Research Grant-in-Aid for Challenging Exploratory Research
OHMORI Ken
Grant amount：\3900000 （ Direct Cost: \3000000 、 Indirect Cost：\900000 ）
This syntheses of C_2-symmetric enantiomerically pure polyparacyclophane derivatives were achieved by Suzuki-Miyaura coupling method, where the synthesis of these C_2 -symmetrical paracyclophanes was based on the hydrogen-bond controlling strategy by using styryl sulfoxide derivatives. Bistriflates, derived from dihydroquinone derivative of monomeric cyclophanes, were used as building blocks for their oligomer synthesis. Incorporation of phenyl spacer to sustain π-conjugation was successful, giving a heptaphenylene derivative. The structure was confirmed by single crystal X-ray analysis, revealing its linear structure. UV-vis and CD spectra of the compound suggested a helical conformation of thepolyphenylene skeleton in organic solvents, such as chloroform.
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Synthetic Study on Bioactive Oligomeric and Polymeric Flavonoids
Grant number：21350050 2009 - 2011
Japan Society for the Promotion of Science Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B) Grant-in-Aid for Scientific Research (B)
OHMORI Ken
Grant amount：\19240000 （ Direct Cost: \14800000 、 Indirect Cost：\4440000 ）
Natural polyphenols have traditional relation to human life as ingredients of wine, tea or herbal medicines, which has stimulated the search for new pharmaceutical candidates relevant to polyphenols. However, the biological studies of polyphenols are often hampered by the difficulty in isolating respective compounds in pure and structurally-defined forms, because the major availability has relied on natural sources, e. g., plant extracts, which are generally a mixture of closely related compounds, hardly tractable even by the aid of modern separation and analytical methods.
This study focused on development of general synthetic method enabling access to various catechin derivatives, and exploited its selective oligomerization. Monomeric catechins are synthesized from 1, 3, 5-trifluorobenzene via intermolecular S_N2 reaction with the B-ring fragment followed by intramolecular S_NAr reaction. Oligomerizations of monomers are conducted based on the orthogonal synthetic strategy, giving higher oligomers ranging from 3-mer to 24-mer. The method was applicable to the synthesis of the hetero-trimer, which was isolated from Ziziphus jujuba, composing of epiafzelechin, epigallocatechin, and catechin units. -
高次複合型カテキンオリゴマーの合成と機能探索に関する研究
Grant number：17685007 2005 - 2007
日本学術振興会 科学研究費助成事業 若手研究(A) 若手研究(A)
大森 建
Grant amount：\28990000 （ Direct Cost: \22300000 、 Indirect Cost：\6690000 ）
カテキン、エピカテキン等のフラボノイド系ポリフェノールは、茶やワインの成分としてなじみ深いが、これらは容易に構造変化を受けやすく、一般に近縁化合物の分離困難な混合物としてしか得られないため、個々の化合物の性質が調べられた例はほとんどない。その一方で、天然由来のポリフェノール類は多種多様な一大化合物群を成しており、カテキンオリゴマーに顕著な抗腫瘍性が報告されたことなどに注目すると、未知の有用な生理活性の発見が期待される。したがって、天然から得ることが難しい各種の類縁体を合成により供給できれば、この領域のさらなる進展に大きく寄与できる。そこで本研究では、カテキン類(モノマー)ならびにカテキンオリゴマーの一般的な合成法の開発を目指し研究を行った。その結果、水酸基の数や立体配置が異なる様々なカテキンユニットを合成とする可能な汎用性の高い方法論を開拓することに成功した。本法の特徴は以下の三点である。第一に、2つの合成単位を設計、合成し、これらをC-O結合を介して結合させる。第二に、Baldwin則では不利とされる(6-endo-tet)型の閉環を避けるため、合成中間体内に存在するオキシラン環を開環し、ハロヒドリンヘと変換する。第三にはピラン環を構築するために4位と4a位の炭素間でC-C結合形成する。実際に本法を用い、ガロカテキン、エピガロカテキンをはじめとする各種のカテキン類縁体を効率的かつ立体選択的に合成することに成功した。
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高次構造を有するフラボン系ポリフェノールの合成研究
Grant number：13740351 2001 - 2002
日本学術振興会 科学研究費助成事業 若手研究(B) 若手研究(B)
大森 建
Grant amount：\2100000 （ Direct Cost: \2100000 ）
フラボン系ポリフェノール類は茶、ワイン、果物等に多く含まれており、抗酸化作用をはじめとし、抗腫瘍作用、血圧上昇抑制作用、抗菌作用等の生理活性を有するが、その多くはフラバン骨格の4位が官能基化されている。そこで本研究においては4位に官能基を備えた種々のフラボノイドの一般的な合成法の開発を行った。
はじめに、フラバン骨格の4位に脱離基を備えたカテキン誘導体の合成を行った。すなわち、カテキンの全ての水酸基をベンジル基で保護した後、DDQ酸化、アセチル化を経て、フラバン骨格の4位にアセトキシ基を導入した。続いて、得られたアセタートを用い実際に、種々の求核剤との反応を試みた。その結果、塩化メチレン中、種々の求核剤存在下(3モル量)、-78℃下にてBF_3・OEt_2(1モル量)を作用させると、速やかに反応が進行し、対応する置換生成物がいずれも収率よく得られることが分った。なお、NMRより、いずれの反応においても、β体が主生成物として得られたことが分った。
続いて、カテキン重合体の合成を行った。具体的には、異なる脱離能を有するカテキン供与体を用い、これらを選択的に活性化するオルソゴナル活性化法に着目し、検討を進めた。その結果、脱離基としてアセタート並びにスルフィドを有するものが有用であった。すなわち、アセタートはBF_3・OEt_2、スルフイドはNISにより速やかに活性化されることが分った。そしてこの条件を用い、カテキンユニットの伸長を試みた結果、実際に三量体、四量体、五量体をそれぞれ高収率で得ることができた。 -
グループ選択的反応を鍵とした新しい合成手法の開発
Grant number：11740347 1999 - 2000
日本学術振興会 科学研究費助成事業 奨励研究(A) 奨励研究(A)
大森 建
Grant amount：\2200000 （ Direct Cost: \2200000 ）
平成11年度から12年度にかけての2年間の研究を通じ、グループ選択的ヒドロアルミニウム化反応を鍵とする第三級アルコール不斉中心の新たな立体選択的構築法を開発した。すなわち、隣接位に不斉点を有するビスアルキニルアルコールに対し、適切な条件でヒドロアルミニウム化反応を行うと、還元反応が一段階で停止し、一方のアルキニル基が優先的に反応することを見出した。そして乳酸由来の非環状基質とグリセリン酸由来の環状基質を用いた反応とでは、それぞれ高選択的に反応が進行するものの、グループ選択性の様式が異なることをつきとめた。また、様々な検討結果から立体制御に必要な要素を抽出し、それらを総合してグループ選択性を合理的に説明できるモデルを提案した。このモデルはリチウムキレート構造における各置換基の占有空間の考察に基づくものであり、種々の反応例についてどちらのアルキニル基が優先して反応するかをよく予測する。さらに、このモデルをヒントとして、選択性を向上させる反応条件を見出した。また、当反応において生成するアルケニルアルミナート中間体を様々な求電子剤で捕捉し、合成上有用な三置換オレフィンを効率的に合成することに成功した。さらに、このグループ選択的ヒドロアルミニウム化反応を反復利用することにより、第三級アルコールに基づく連続不斉中心を高選択的に構築できることも見出した。これら一連の生成物は様々な化学変換が可能なアルキニル基とアルケニル基を備えた第三級アルコールであり、こうした連続構造を持つ天然有機化合物の合成に有用である。
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Synthetic Study of Pradimicns, Antiviral Antibiotics Possessing the Binding Abilities to Oligosacchrides
Grant number：10440214 1998 - 1999
Japan Society for the Promotion of Science Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B) Grant-in-Aid for Scientific Research (B)
SUZUKI Keisuke, OHMORI Ken, MATSUMOTO Takashi
Grant amount：\13400000 （ Direct Cost: \13400000 ）
The pradimicin-benanomicin antibiotics constitute a new class of natural products with a benzo[a]naphthacenequinone core wkh an amino acid and a disaccharide.They show anti-fungal and anti-HIV activities, which are related to the selective binding abilities to mannose-rich oligosaccharides, e.g. the mannane surface of fungi or gp 120 of HIV. The unique structure as well as the significant biological activities led me to undertake the synthesis of this class of compounds.
The most intriguing challenge among the synthetic issues is the control of the vicinal diol stereogenicities at the corner of the pentacyclic skeleton comprises, to which we explored the possible use of intramolecular pinacol coupling of bis-aldehyde. Along these lines, we found that this reaction is useful for the above issue.
The SmIィイD22ィエD2-mediated pinacol coupling of biphenyl o, o'-dialdehyde was found to proceed stereo selectivelly and gave only trans diol, which enabled us to achieve the synthesis of the trans diol structure of B ring as diastereomerically pure form. Furthermore, the reaction proved to proceed stereospecifically, thereby enabling the full transmission of the axial chirality into the two central chiralities. Thus, we studied the stereoselective and -specific pinacol coupling of bis-aldehyde, providing the requisite trans-diol in enantio- and diastereomerically pure form, which served as a basic strategy for the total synthesis of the pradimicin-benanomicin class antibiotics.
Total synthesis of the pradimicinone (benanomicinone), the common aglycon of the class of natural products, based on the above mentioned pinacol cyclization, has been achieved. -
Development of viable synthetic route to the furaquinocins and its application to creating new antitumor agents
Grant number：09554045 1997 - 1999
Japan Society for the Promotion of Science Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)
SUZUKI Keisuke, FUJIMOTO Katsumi, OHMORI Ken, MATSUMOTO Takashi
Grant amount：\10200000 （ Direct Cost: \10200000 ）
An efficient and flexible synthetic route to the furaquinocins, a new class of antibiotics which show cytotoxic activity against HeLa S3 and B16 melanoma cells but no antimicrobial activity, was developed. These compounds pose new synthetic challenges due to their unique hybrid structure composed of the polyketide-derived naphthoquinone and the isoprenoid side chain, including (1) stereocontrol of three contiguous stereogenic centers at C-2, C-3 (quaternary), and C-10, (2) selective construction of the densely functionalized naphthoquinone, and (3) establishment of the sterically congested aromatic-isoprenoid hybrid structure.
Stereocontrolled construction of two of the three contiguous stereogenic centers, including a quaternary chiral center, was effected by the 1,2-rearrangement of optically active epoxy alcohol armed with the cobalt-complexed alkyne as the migrating group. The alkyne in the resulting homopropargyl alcohol, after decoordination of the cobalt, effectively worked as the C2 unit for constructing the naphthofuran skeleton by an electrocyclic benzannulation. The third chiral center was constructed by stereoselective methylenation of the aldehyde, adjacent to the quaternary chiral center, by a sulfur ylide. Through the resulting epoxide as the common intermediate, total syntheses of furaquinocin D, furaquinocin A, furaquinocin B, and furaquinocin H were achieved in a convergent manner.
Biological activity test revealed that some of the synthetic intermediates exhibit potent cyctocidal activities comparable to natural furaquinocins, which provides a valuable information for designing new synthetic antitumor agents. -
糖錯結合性物質の合成と分子設計に関する研究
Grant number：09740463 1997 - 1998
日本学術振興会 科学研究費助成事業 奨励研究(A)
大森 健
Grant amount：\2000000 （ Direct Cost: \2000000 ）
プラジミシン類はActinomadura hibiscaより単離された化合物群であり、抗真菌、抗HIV活性を示す。その化学構造は、母核となるベンゾ[a]ナフタセンキノン骨格にアミノ酸、および糖が結合した構造を持つ。本研究では、この特徴的な構造と生理活性に興味を持ち、これらの合成研究を行った。
本研究において、鍵となるフェナントレンジオール骨格を立体選択的かつ、立体特異的に構築する有効な手法を見出した。すなわち、芳香族ジアルデヒドに対しSmI_2を作用させると対応するジオールを与え、その立体化学はトランスのみであることが分った。また、アトロプ異性的に純粋な芳香族ジアルデヒドを用いて環化の条件に付すと、それぞれ光学的に純粋なトランスジオールを与えることが判明した。すなわち、反応を通じて軸不斉を二つの中心不斉へと転写できることが明らかとなった。
この知見をもとに、上記の反応を利用して実際に光学的に純粋なプラジミシンのB環部骨格を構築した。さらに検討を加え、効率的なプラジミシノンの合成法を開発した。
続いて、プラジミシン類の構成糖に相当する糖供与体の合成を検討した。その結果、キシロース誘導体、およびトモサミン誘導体を各合成し、それらをグリコシル化することにより目的のフッ素化二糖を合成することができた。さらに、これをアルコール共存下、Cp_2HfCl_2-AgClO_4複合活性化剤で処理すると円滑に反応が進行し、望みのグリコシル体が得られることが分かった。