1
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Sato K, Fujita T, Takeuchi T, Suzuki T, Ikeuchi K, Tanino K. Alcohol synthesis based on the S N2 reactions of alkyl halides with the squarate dianion. Org Biomol Chem 2024; 22:1369-1373. [PMID: 38232248 DOI: 10.1039/d3ob01507f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2024]
Abstract
A convenient method has been developed for transforming alkyl halides into the corresponding alcohols via an SN2 reaction. Treatment of an alkyl halide with the squarate dianion at high temperature produces mono-alkyl squarate, and a one-pot basic hydrolysis of the intermediate affords the alcohol in good yield.
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Affiliation(s)
- Kazuto Sato
- Graduate School of Chemical Sciences and Engineering, Hokkaido University, Sapporo 060-0810, Japan
| | - Tomoyuki Fujita
- Graduate School of Chemical Sciences and Engineering, Hokkaido University, Sapporo 060-0810, Japan
| | - Takashi Takeuchi
- Graduate School of Chemical Sciences and Engineering, Hokkaido University, Sapporo 060-0810, Japan
| | - Takahiro Suzuki
- Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo 060-0810, Japan.
| | - Kazutada Ikeuchi
- Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo 060-0810, Japan.
| | - Keiji Tanino
- Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo 060-0810, Japan.
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2
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Ikeuchi K. Development of Methodologies toward the Unified Synthesis of Ellagitannins. Chem Pharm Bull (Tokyo) 2024; 72:349-359. [PMID: 38556326 DOI: 10.1248/cpb.c23-00920] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/02/2024]
Abstract
Ellagitannins, a class of polyphenols with divergent structures, have attracted considerable attention from synthetic organic chemists. The basic structures in ellagitannins contain esters of D-glucose with galloyl or hexahydroxyldiphenoyl groups, as well as diaryl ether structures. Thus, the synthesis methodologies of such components have been developed by various groups, including our group. This review describes the synthetic methods reported by our group during 2017-2023, aimed at increasing the number of ellagitannins that can be chemically synthesized. In addition, recent related reports are introduced.
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Affiliation(s)
- Kazutada Ikeuchi
- Graduate School of Pharmaceutical Sciences, Nagoya City University
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3
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Suzuki T, Ikeda W, Kanno A, Ikeuchi K, Tanino K. Diastereoselective Synthesis of trans-anti-Hydrophenanthrenes via Ti-mediated Radical Cyclization and Total Synthesis of Kamebanin. Chemistry 2023; 29:e202203511. [PMID: 36529687 DOI: 10.1002/chem.202203511] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2022] [Revised: 12/16/2022] [Accepted: 12/17/2022] [Indexed: 12/23/2022]
Abstract
Ent-kaurenes consist of an ABC-ring based on a trans-anti-hydrophenanthrene skeleton and a D ring with an exomethylene. Highly oxygen-functionalized ent-kauren-15-ones have promising antiinflammatory pharmacological activity. In this study, we developed a novel diastereoselective synthesis of trans-anti-hydrophenanthrenes via a Ti-mediated reductive radical cyclization. We also demonstrated the applicability of this method by developing the first total synthesis of (±)-kamebanin (longest linear sequence; 17 steps, overall yield; 6.5 %). Furthermore, this synthesis provided a formal semi-pinacol rearrangement for the construction of the quaternary carbon at C8 and a novel Thorpe-Ziegler-type reaction for the construction of the D-ring.
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Affiliation(s)
- Takahiro Suzuki
- Department of Chemistry, Faculty of Science, Hokkaido University, 060-0810, Sapporo, Hokkaido, Japan
| | - Wataru Ikeda
- Graduate School of Chemical Sciences and Engineering, Hokkaido University, 060-0810, Sapporo, Hokkaido, Japan
| | - Ayaka Kanno
- Graduate School of Chemical Sciences and Engineering, Hokkaido University, 060-0810, Sapporo, Hokkaido, Japan
| | - Kazutada Ikeuchi
- Department of Chemistry, Faculty of Science, Hokkaido University, 060-0810, Sapporo, Hokkaido, Japan
| | - Keiji Tanino
- Department of Chemistry, Faculty of Science, Hokkaido University, 060-0810, Sapporo, Hokkaido, Japan
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4
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Ikeuchi K, Haraguchi S, Fujii R, Yamada H, Suzuki T, Tanino K. Total Synthesis of (+)-Coriamyrtin via a Desymmetrizing Strategy Involving a 1,3-Cyclopentanedione Moiety. Org Lett 2023; 25:2751-2755. [PMID: 36853202 DOI: 10.1021/acs.orglett.3c00249] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/01/2023]
Abstract
We describe the total synthesis of (+)-coriamyrtin, which bears a highly functionalized cis-hydrindane skeleton and is a widely known neurotoxin of the Coriariaceae family. Our synthetic strategy involves the highly stereoselective construction of the cis-hydrindane skeleton via a desymmetrizing strategy involving a 1,3-cyclopentanedione moiety using an intramolecular aldol reaction and the formation of the 1,3-diepoxide moiety of coriamyrtin through the elaborate functionalization of the cyclopentane ring in the bicyclic structure.
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Affiliation(s)
- Kazutada Ikeuchi
- Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo 060-0810, Japan
| | - Shota Haraguchi
- School of Science and Technology, Kwansei Gakuin University, Sanda 669-1337, Japan
| | - Ryo Fujii
- School of Science, Hokkaido University, Sapporo 060-0810, Japan
| | - Hidetoshi Yamada
- School of Science and Technology, Kwansei Gakuin University, Sanda 669-1337, Japan
| | - Takahiro Suzuki
- Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo 060-0810, Japan
| | - Keiji Tanino
- Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo 060-0810, Japan
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5
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Ikeuchi K, Ozoe Y, Kato R, Suzuki T, Tanino K. Synthesis of 2-alkyl-2-(2-furanyl)-1,3-cyclopentanediones. SYNTHESIS-STUTTGART 2022. [DOI: 10.1055/a-2004-1333] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
2,2-Disubstituted-1,3-cyclopentanediones are versatile building blocks for synthesizing complex natural products with bicyclic structures including cyclopentane rings. The reported method for the synthesis of these compounds involves the semi-pinacol rearrangement of a Mukaiyama-aldol adduct prepared from a ketone/ketal and 1,2-bis(trimethylsilyloxy)cyclobutene. However, the adoption of α-oxy-functionalized ketones/ketals is quite difficult, as demonstrated by our experiments. To overcome this limitation of the method, we used 2-acylfuran derivatives as the reactants to synthesize 2,2-disubstituted-1,3-cyclopentanediones. Furthermore, two reaction conditions, that is, the use of 1.4 equivalents of a boron trifluoride-diethyl ether complex or 0.4 and 0.2 equivalents of trimethylsilyl triflate and methoxytrimethylsilane, respectively, were established for the conversion of 2-acylfurans into the corresponding 1,3-cyclopentanediones in acceptable yields. The transformations of the furan rings in the obtained products were also investigated.
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Affiliation(s)
| | - Yusuke Ozoe
- Graduate School of Chemical Sciences and Engineering, Hokkaido University, Sapporo, Japan
| | - Ranmaru Kato
- Graduate School of Chemical Sciences and Engineering, Hokkaido University, Sapporo, Japan
| | - Takahiro Suzuki
- Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo, Japan
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6
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Kato R, Saito H, Ikeuchi K, Suzuki T, Tanino K. Total Synthesis and Structural Revision of the 6,11-Epoxyisodaucane Natural Sesquiterpene Using an Anionic 8π Electrocyclic Reaction. Org Lett 2022; 24:7939-7943. [PMID: 36268969 DOI: 10.1021/acs.orglett.2c03068] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A new synthetic strategy that forms a seven-membered carbocycle using an anionic 8π electrocyclic reaction facilitated the first total synthesis of the 6,11-epoxyisodaucane natural sesquiterpene in 9.0% yield over 10 steps in the longest linear sequence. The misassigned proposed stereochemistry was corrected by the synthesis of both the proposed structure and its C6 epimer. In addition, the 5-7-fused ring system was concisely constructed by tandem decyanation/five-membered-ring formation from an epoxynitrile.
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Affiliation(s)
- Ranmaru Kato
- Graduate School of Chemical Sciences and Engineering, Hokkaido University, Sapporo 060-0810, Japan
| | - Hiroki Saito
- Graduate School of Chemical Sciences and Engineering, Hokkaido University, Sapporo 060-0810, Japan
| | - Kazutada Ikeuchi
- Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo 060-0810, Japan
| | - Takahiro Suzuki
- Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo 060-0810, Japan
| | - Keiji Tanino
- Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo 060-0810, Japan
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7
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Kato K, Ikeuchi K, Suzuki T, Tanino K. Total Synthesis of 2-Isocyanoallopupukeanane: Construction of Caged Skeleton by Intramolecular Alkylation of Bromonitriles. Org Lett 2022; 24:6407-6411. [PMID: 36017948 DOI: 10.1021/acs.orglett.2c02434] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A new method for constructing the bicyclo[3.2.1]octane skeleton was developed by the intramolecular alkylation of a nitrile-side-chain-containing cyclohexanone derivative. The cyclization precursors were prepared via the stereoselective bromination of the triisopropylsilyl enol ethers of 4-substituted cyclohexanones. Upon treatment with LiNEt2, the bromonitriles underwent a stereoselective intramolecular SN2 reaction to afford bicyclo[3.2.1]octane derivatives with a cyano group on the convex face. The total synthesis of 2-isocyanoallopupukeanane (6.5% yield) from methyl vinyl ketone was accomplished via a 17-step transformation.
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Affiliation(s)
- Kosuke Kato
- Graduate School of Chemical Sciences and Engineering, Hokkaido University, Sapporo 060-0810, Japan
| | - Kazutada Ikeuchi
- Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo 060-0810, Japan
| | - Takahiro Suzuki
- Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo 060-0810, Japan
| | - Keiji Tanino
- Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo 060-0810, Japan
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8
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Ogura R, Satoh K, Kiuchi W, Kato K, Ikeuchi K, Suzuki T, Tanino K. Two-Step Method for Constructing a Quaternary Carbon Atom with a Geminal Divinyl Group from a Ketone. Org Lett 2022; 24:5040-5044. [DOI: 10.1021/acs.orglett.2c01799] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Ryota Ogura
- Graduate School of Chemical Sciences and Engineering, Hokkaido University, Sapporo 060-0810, Japan
| | - Kazuto Satoh
- Graduate School of Chemical Sciences and Engineering, Hokkaido University, Sapporo 060-0810, Japan
| | - Wataru Kiuchi
- Graduate School of Chemical Sciences and Engineering, Hokkaido University, Sapporo 060-0810, Japan
| | - Kosuke Kato
- Graduate School of Chemical Sciences and Engineering, Hokkaido University, Sapporo 060-0810, Japan
| | - Kazutada Ikeuchi
- Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo 060-0810, Japan
| | - Takahiro Suzuki
- Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo 060-0810, Japan
| | - Keiji Tanino
- Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo 060-0810, Japan
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9
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Ikeuchi K, Haraguchi S, Yamada H, Tanino K. Model Synthetic Study of Tutin, a Picrotoxane-Type Sesquiterpene: Stereoselective Construction of a cis-Fused 5,6-Ring Skeleton. Chem Pharm Bull (Tokyo) 2022; 70:435-442. [PMID: 35650040 DOI: 10.1248/cpb.c22-00083] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Picrotoxinin, coriamyrtin, and tutin are representative natural products classified as picrotoxane-type sesquiterpenes and they function as strong neurotoxins. Because they possess a cis-fused 5,6-ring skeleton with a highly congested functionalization, organic chemistry researchers have pursued the development of a stereoselective synthesis method for such skeleton. This study aims to stereoselectively synthesize the cis-fused 5,6-ring skeleton with two tetrasubstituted carbons at both angular positions using a model compound. The results revealed that the desymmetrization of the 2-methyl-1,3-cyclopentanedione moiety via the DL-proline-mediated intramolecular aldol reaction of a pentanal derivative bearing an isopropenyl group and the five-membered ring at the 3- and 5-position, respectively, provided the desired cis-fused skeleton. This reaction can construct four contiguous stereogenic centers of the bicyclic skeleton with the two angular positions in good yield with high stereoselectivity. Further, this reaction was applied to the kinetic resolution of the racemate using L-proline, providing the enantiomeric pure aldol product with the desired skeleton. This method can be utilized for total synthesis of picrotoxane-type sesquiterpenes.
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10
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Saito H, Kato R, Ikeuchi K, Suzuki T, Tanino K. 8π Electrocyclic Reaction of Phosphonate Derivatives: Access to Seven-Membered Cross-Conjugated Cyclic Trienes. Org Lett 2021; 23:9606-9610. [PMID: 34881898 DOI: 10.1021/acs.orglett.1c03815] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
An anionic 8π electrocyclic reaction of 4-(diethoxyphosphoryl)-1,3,6-heptatriene derivatives was developed. Under the influence of a base, the substrate underwent deprotonation at the C5 position followed by the 8π electrocyclization of the resulting heptatrienyl anion. The subsequent Horner-Wadsworth-Emmons reaction in one pot, following the addition of an aldehyde, resulted in the production of the 3-alkylidene-1,4-cycloheptadiene derivative. The electrocyclic reaction proceeded in a stereospecific manner, resulting in the stereocontrolled formation of two neighboring stereogenic centers.
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Affiliation(s)
- Hiroki Saito
- Graduate School of Chemical Sciences and Engineering, Hokkaido University, Sapporo 060-0810, Japan
| | - Ranmaru Kato
- Graduate School of Chemical Sciences and Engineering, Hokkaido University, Sapporo 060-0810, Japan
| | - Kazutada Ikeuchi
- Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo 060-0810, Japan
| | - Takahiro Suzuki
- Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo 060-0810, Japan
| | - Keiji Tanino
- Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo 060-0810, Japan
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11
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Ikeuchi K, Sasage T, Yamada G, Suzuki T, Tanino K. Synthesis of a Bicyclo[2.2.1]heptane Skeleton with Two Oxy-Functionalized Bridgehead Carbons via the Diels-Alder Reaction. Org Lett 2021; 23:9123-9127. [PMID: 34761677 DOI: 10.1021/acs.orglett.1c03451] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We describe a synthetic method for a bicyclo[2.2.1]heptane skeleton with two oxy-functionalized bridgehead carbons. This method involves an intermolecular Diels-Alder reaction using 5,5-disubstituted 1,4-bis(silyloxy)-1,3-cyclopentadienes, the diene structure of which has never been synthesized. Furthermore, the intramolecular Diels-Alder reaction using a diene bearing a dienophile moiety at the C-5 position can provide a tricyclic carbon framework that includes the bicyclo[2.2.1]heptane skeleton. The novel bicyclo[2.2.1]heptane derivatives could be utilized as versatile building blocks for organic synthetic chemistry.
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Affiliation(s)
- Kazutada Ikeuchi
- Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo 060-0810, Japan
| | - Tomonari Sasage
- Graduate School of Chemical Sciences and Engineering, Hokkaido University, Sapporo 060-0810, Japan
| | - Gen Yamada
- Graduate School of Chemical Sciences and Engineering, Hokkaido University, Sapporo 060-0810, Japan
| | - Takahiro Suzuki
- Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo 060-0810, Japan
| | - Keiji Tanino
- Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo 060-0810, Japan
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12
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Kato R, Saito H, Uda S, Domon D, Ikeuchi K, Suzuki T, Tanino K. Synthesis of Seven-Membered Cross-Conjugated Cyclic Trienes by 8π Electrocyclic Reaction. Org Lett 2021; 23:8878-8882. [PMID: 34714079 DOI: 10.1021/acs.orglett.1c03383] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
A method for the synthesis of 3-methylene-1,4-cycloheptadiene derivatives via an 8π electrocyclization reaction was developed. The triene substrate bearing a phosphate or carbamate group was prepared from γ,δ-unsaturated esters and α,β-unsaturated aldehydes in four steps. Upon treatment with NaHMDS or KHMDS, the substrate formed a heptatrienyl anion, which underwent electrocyclization and subsequent β-elimination of the leaving group. The product could be converted into a tropylium salt in two steps.
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Affiliation(s)
- Ranmaru Kato
- Graduate School of Chemical Sciences and Engineering, Hokkaido University, Sapporo 060-0810, Japan
| | - Hiroki Saito
- Graduate School of Chemical Sciences and Engineering, Hokkaido University, Sapporo 060-0810, Japan
| | - Shoko Uda
- Graduate School of Chemical Sciences and Engineering, Hokkaido University, Sapporo 060-0810, Japan
| | - Daisuke Domon
- Graduate School of Chemical Sciences and Engineering, Hokkaido University, Sapporo 060-0810, Japan
| | - Kazutada Ikeuchi
- Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo 060-0810, Japan
| | - Takahiro Suzuki
- Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo 060-0810, Japan
| | - Keiji Tanino
- Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo 060-0810, Japan
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13
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Tanino K, Yukutake Y, Hiramatsu T, Itoh R, Ikeuchi K, Suzuki T. Synthetic Studies toward Tubiferal A: Asymmetric Synthesis of a Model ABC-Ring Compound. Synlett 2021. [DOI: 10.1055/a-1697-7477] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
AbstractSynthetic studies on an ABC-ring model of tubiferal A, a triterpenoid isolated from the fruit bodies of the Tubifera dimorphotheca myxomycete, are described. The stereogenic centers at the angular positions were constructed through the stereoselective addition of a C-ring allylborane followed by an Eschenmoser–Claisen rearrangement reaction prior to the formation of the AB-ring system by a double intramolecular alkylation reaction of a dichloro nitrile intermediate.
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Affiliation(s)
- Keiji Tanino
- Department of Chemistry, Faculty of Science, Hokkaido University
| | - Yuki Yukutake
- Graduate School of Chemical Sciences and Engineering, Hokkaido University
| | - Takahiro Hiramatsu
- Graduate School of Chemical Sciences and Engineering, Hokkaido University
| | - Ryusei Itoh
- Graduate School of Chemical Sciences and Engineering, Hokkaido University
| | - Kazutada Ikeuchi
- Department of Chemistry, Faculty of Science, Hokkaido University
| | - Takahiro Suzuki
- Department of Chemistry, Faculty of Science, Hokkaido University
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14
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Tanino K, Kishi JI, Ikeuchi K, Suzuki T. Synthetic Studies of Daphniphyllum Alkaloids: A New Method for the Construction of [7-5-5] All-Carbon Tricyclic Skeleton. Synlett 2021. [DOI: 10.1055/a-1682-9415] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Abstract
Daphniphyllum alkaloids have complex molecular structures; consequently, their synthesis can be challenging. A new method for the construction of the [7-5-5] tricyclic core of Daphniphyllum alkaloids was developed. The bicyclo[5.3.0]decane skeleton was constructed through a divinylcyclopropane rearrangement of a cyclopentenone derivative with a vinylcyclopropyl group at the β-position. After introduction of a 2-iodoethyl group by a regioselective Michael addition with phenyl vinyl selenone, the [7-5-5] tricyclic system was formed by intramolecular alkylation of a cyclopentadienyl anion species.
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Affiliation(s)
- Keiji Tanino
- Department of Chemistry, Faculty of Science, Hokkaido University
| | - Jun-ichiro Kishi
- Graduate School of Chemical Sciences and Engineering, Hokkaido University
| | - Kazutada Ikeuchi
- Department of Chemistry, Faculty of Science, Hokkaido University
| | - Takahiro Suzuki
- Department of Chemistry, Faculty of Science, Hokkaido University
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15
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Ikeuchi K, Matsumoto S, Ikuta D, Yamada H. Glycosylation by Alkyne Activation of the 2-O-Substituted Propargyl Group in a β-Phenylthioglucoside with a 5
S
1 Conformation. Synlett 2021. [DOI: 10.1055/a-1384-2931] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
AbstractGenerally, glycosylation reactions activate an anomeric substituent in a glycosyl donor to generate an oxocarbenium ion intermediate. Here we report a novel glycosylation reaction triggered by the activation of a 2-O-substituted propargyl group in a 3,6-O-1,1′-[(ethane-1,2-diyl)bibenzene-2,2′-bis(methylene)]-β-thioglucoside. This reaction proceeds through a cationic Au(I)-mediated intramolecular migration of the anomeric substituent onto the alkyne moiety of the propargyl group, followed by α-attack by the hydroxy group in the glycosyl acceptor on the oxocarbenium ion. The migration of the anomeric group occurs selectively through a 6-exo-dig pathway. The 2-(phenylsulfanyl)prop-2-en-1-yl group produced during the glycosylation is removable under conditions similar to those used for removing an allyl group. This reaction will be developed for further applications in orthogonal oligosaccharide synthesis.
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Affiliation(s)
- Kazutada Ikeuchi
- Department of Chemistry, Faculty of Science, Hokkaido University
- School of Science and Technology, Kwansei Gakuin University
| | | | - Daiki Ikuta
- School of Science and Technology, Kwansei Gakuin University
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16
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Bando M, Kawasaki Y, Nagata O, Okada Y, Ikuta D, Ikeuchi K, Yamada H. β-Selective Glycosylation Using Axial-Rich and 2-O-Rhamnosylated Glucosyl Donors Controlled by the Protecting Pattern of the Second Sugar. Chem Pharm Bull (Tokyo) 2021; 69:124-140. [PMID: 33390514 DOI: 10.1248/cpb.c20-00733] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Herein, we describe two counterexamples of the previously reported β/α-selectivity of 96/4 for glycosylation using ethyl 2-O-[2,3,4-tris-O-tert-butyldimethylsilyl (TBS)-α-L-rhamnopyranosyl]-3,4,6-tris-O-TBS-thio-β-D-glucopyranoside as the glycosyl donor. Furthermore, we investigated the effects of protecting group on the rhamnose moieties in the glycosylation with cholestanol and revealed that β-selectivity originated from the two TBS groups at the 3-O and 4-O positions of rhamnose. In contrast, the TBS group at the 2-O position of rhamnose hampered the β-selectivity. Finally, the β/α-selectivity during the glycosylation was enhanced to ≥99/1. The results obtained herein suggest that the protecting groups on the sugar connected to the 2-O of a glycosyl donor with axial-rich conformation can control the stereoselectivity of glycosylation.
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Affiliation(s)
- Masafumi Bando
- School of Science and Technology, Kwansei Gakuin University
| | - Yuri Kawasaki
- School of Science and Technology, Kwansei Gakuin University
| | - Osamu Nagata
- School of Science and Technology, Kwansei Gakuin University
| | - Yasunori Okada
- School of Science and Technology, Kwansei Gakuin University
| | - Daiki Ikuta
- School of Science and Technology, Kwansei Gakuin University
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Yamashita K, Kume Y, Ashibe S, Puspita CAD, Tanigawa K, Michihata N, Wakamori S, Ikeuchi K, Yamada H. Total Synthesis of Mallotusinin. Chemistry 2020; 26:16408-16421. [PMID: 32614090 DOI: 10.1002/chem.202002753] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Indexed: 11/11/2022]
Abstract
The total synthesis of mallotusinin, which bears a tetrahydroxydibenzofuranoyl (THDBF) bridge between the 2-oxygen and 4-oxygen of glucose on corilagin with a 3,6-O-(R)-hexahydroxydiphenoyl (HHDP) bridge, is described. The key features of the total synthesis are: 1) improvements of our previously reported method to synthesize corilagin; 2) establishment of the THDBF skeleton via an unusual intramolecular SN Ar reaction of an HHDP analogue, and 3) the application of a two-step bislactonization strategy for a HHDP bridge construction into the 2,4-O-THDBF bridge. Oxidative phenol coupling of 1,2,4-orthoacetyl-3,6-di-(4-O-benzylgalloyl)-α-d-glucopyranose and the orthoester cleavage of the coupling product without the pyranose-furanose ring transformation are key reactions for the improved synthesis of corilagin, which enabled the adequate supply of a corilagin precursor that was required to develop the mallotusinin synthesis. These established methods are expected to help develop the synthesis of other ellagitannins with a bridge between the two oxygens of corilagin.
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Affiliation(s)
- Kohei Yamashita
- School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda, 669-1337, Japan
| | - Yuji Kume
- School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda, 669-1337, Japan
| | - Seiya Ashibe
- School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda, 669-1337, Japan
| | - Cicilia A D Puspita
- School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda, 669-1337, Japan
| | - Kotaro Tanigawa
- School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda, 669-1337, Japan
| | - Naoki Michihata
- School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda, 669-1337, Japan
| | - Shinnosuke Wakamori
- School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda, 669-1337, Japan
| | - Kazutada Ikeuchi
- School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda, 669-1337, Japan.,Department of Chemistry, Faculty of Science, Hokkaido University, Kita 10, Nishi 8, Kita-ku, Sapporo, 060-0810, Japan
| | - Hidetoshi Yamada
- School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda, 669-1337, Japan
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18
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Ikeuchi K, Murasawa K, Arai T, Yamada H. p-Methylbenzyl 2,2,2-Trichloroacetimidate: Simple Preparation and Application to Alcohol Protection. CHEM LETT 2020. [DOI: 10.1246/cl.200303] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Kazutada Ikeuchi
- School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda, Hyogo 669-1337, Japan
- Department of Chemistry, Faculty of Science, Hokkaido University, Kita 10, Nishi 8, Kita-ku, Sapporo, Hokkaido 060-0810, Japan
| | - Kentaro Murasawa
- School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda, Hyogo 669-1337, Japan
| | - Tomoki Arai
- School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda, Hyogo 669-1337, Japan
| | - Hidetsohi Yamada
- School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda, Hyogo 669-1337, Japan
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19
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Hashimoto H, Ishimoto T, Konishi H, Hirokane T, Wakamori S, Ikeuchi K, Yamada H. Synthesis of an Ellagitannin Component, the Macaranoyl Group with a Tetra- ortho-Substituted Diaryl Ether Structure. Org Lett 2020; 22:6729-6733. [PMID: 32845154 DOI: 10.1021/acs.orglett.0c02066] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Herein, a practical synthesis of the macaranoyl group contained in ellagitannins, i.e., a C-O digallate structure with a tetra-ortho-substituted diaryl ether bond, is described. The methodology involved an oxa-Michael addition/elimination reaction between a brominated ortho-quinone monoketal and a phenol with a hexahydroxydiphenoyl moiety in the presence of 18-crown-6 under dark conditions, followed by reductive aromatization. The existence of rotamers originating from the constructed ether moiety is discussed as well.
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Affiliation(s)
- Hajime Hashimoto
- School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda, Hyogo 669-1337, Japan
| | - Takayuki Ishimoto
- School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda, Hyogo 669-1337, Japan
| | - Hayato Konishi
- School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda, Hyogo 669-1337, Japan
| | - Tsukasa Hirokane
- School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda, Hyogo 669-1337, Japan
| | - Shinnosuke Wakamori
- School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda, Hyogo 669-1337, Japan
| | - Kazutada Ikeuchi
- School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda, Hyogo 669-1337, Japan.,Department of Chemistry, Faculty of Science, Hokkaido University, Kita 10, Nishi 8, Kita-ku, Sapporo, 060-0810, Japan
| | - Hidetoshi Yamada
- School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda, Hyogo 669-1337, Japan
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20
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Abstract
This study involves the total synthesis of casuarinin, a naturally occurring ellagitannin, in which an open-chain glucose is esterified with two (S)-hexahydroxydiphenoyl (HHDP) groups. One HHDP group incorporates a C-glycosidic bond between its benzene ring and the glucose moiety, which was constructed with complete stereoselectivity using a benzyl oxime group that opened the glucopyranose ring and acted as a scaffold for C-glycoside production. This total synthesis enables future structure-activity relationship studies of this compound.
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Affiliation(s)
- Shinnosuke Wakamori
- School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda, Hyogo 669-1337, Japan
| | - Shintaro Matsumoto
- School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda, Hyogo 669-1337, Japan
| | - Reina Kusuki
- School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda, Hyogo 669-1337, Japan
| | - Kazutada Ikeuchi
- School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda, Hyogo 669-1337, Japan
| | - Hidetoshi Yamada
- School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda, Hyogo 669-1337, Japan
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21
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Affiliation(s)
- Kazutada Ikeuchi
- School of Science and Technology; Kwansei Gakuin University; 2-1 Gakuen 669-1337 Sanda Japan
| | - Tatsuya Ueji
- School of Science and Technology; Kwansei Gakuin University; 2-1 Gakuen 669-1337 Sanda Japan
| | - Shintaro Matsumoto
- School of Science and Technology; Kwansei Gakuin University; 2-1 Gakuen 669-1337 Sanda Japan
| | - Shinnosuke Wakamori
- School of Science and Technology; Kwansei Gakuin University; 2-1 Gakuen 669-1337 Sanda Japan
| | - Hidetoshi Yamada
- School of Science and Technology; Kwansei Gakuin University; 2-1 Gakuen 669-1337 Sanda Japan
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22
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Konishi H, Hirokane T, Hashimoto H, Ikeuchi K, Matsumoto S, Wakamori S, Yamada H. Synthesis of diaryl ether components of ellagitannins using ortho-quinone with consonant mesomeric effects. Chem Commun (Camb) 2020; 56:3991-3994. [DOI: 10.1039/d0cc00889c] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Methods for synthesizing C–O digallate structures, the basic unit of diaryl ether components of natural ellagitannins, are described. In the designed building block, consonantly overlapped mesomeric effects enhanced its electrophilicity.
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Affiliation(s)
- Hayato Konishi
- School of Science and Technology
- Kwansei Gakuin University
- Hyogo 669-1337
- Japan
| | - Tsukasa Hirokane
- School of Science and Technology
- Kwansei Gakuin University
- Hyogo 669-1337
- Japan
| | - Hajime Hashimoto
- School of Science and Technology
- Kwansei Gakuin University
- Hyogo 669-1337
- Japan
| | - Kazutada Ikeuchi
- School of Science and Technology
- Kwansei Gakuin University
- Hyogo 669-1337
- Japan
| | - Shintaro Matsumoto
- School of Science and Technology
- Kwansei Gakuin University
- Hyogo 669-1337
- Japan
| | - Shinnosuke Wakamori
- School of Science and Technology
- Kwansei Gakuin University
- Hyogo 669-1337
- Japan
| | - Hidetoshi Yamada
- School of Science and Technology
- Kwansei Gakuin University
- Hyogo 669-1337
- Japan
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23
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Abstract
We describe the practical removal of p-methylbenzyl (MBn) protections of alcohols by treatment with 2,3-dichloro-5,6-dicyano-p-benzoquinone. When a molecule bears benzyl and MBn groups, the oxidant selectively removes the latter groups. Further, the MBn groups tolerate ceric ammonium nitrate, resulting in chemoselective removal of the p-methoxybenzyl group in the presence of the MBn groups. These orthogonal alcohol deprotections would provide novel synthetic strategies of organic compounds.
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Affiliation(s)
- Kazutada Ikeuchi
- School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda 669-1337, Japan.,Department of Chemistry, Faculty of Science, Hokkaido University, North 10, West 8, Kita-ku, Sapporo 060-0810, Japan
| | - Kentaro Murasawa
- School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda 669-1337, Japan
| | - Kenya Ohara
- School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda 669-1337, Japan
| | - Hidetoshi Yamada
- School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda 669-1337, Japan
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24
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Abstract
We describe a method for obtaining various allylic, benzylic, and glucosyl 2,2,2-trichloroacetimidates (TCAIs) as stainless liquids or solids at the crude stage. The general synthetic method for the preparation of TCAIs often leads to stained products, and further purification of crude TCAIs causes decomposition due to their instability. In the described method, we use a solvent that barely dissolves the reactant, providing stainless and sufficiently pure TCAIs without requiring a purification step. Furthermore, the reaction mixture is turbid at the beginning and clear at the end, allowing us to monitor the progress of the reaction visually.
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Affiliation(s)
- Kazutada Ikeuchi
- School of Science and Technology
- Department of Chemistry, Faculty of Science, Hokkaido University
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25
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Ikuta D, Hirata Y, Wakamori S, Shimada H, Tomabechi Y, Kawasaki Y, Ikeuchi K, Hagimori T, Matsumoto S, Yamada H. Conformationally supple glucose monomers enable synthesis of the smallest cyclodextrins. Science 2019; 364:674-677. [DOI: 10.1126/science.aaw3053] [Citation(s) in RCA: 57] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2018] [Accepted: 03/28/2019] [Indexed: 11/02/2022]
Abstract
Cyclodextrins (CDs) are cyclic oligomers of α-1,4-d-glucopyranoside and are known mainly as hexamers to octamers. The central cavities of CDs can retain small molecules, enabling diverse applications. The smallest members, CD3 and CD4, have ring sizes too small to permit the most stable conformations of glucopyranose and have not been accessible synthetically. In this study, we present methods to chemically synthesize both CD3 and CD4. The main factor in the successful synthesis is the creation of a glucopyranose ring conformationally counterbalanced between equatorial- and axial-rich forms. This suppleness is imparted by a bridge between O-3 and O-6 of glucose, which enables the generation of desirable, albeit deformed, conformers when synthesizing the cyclic trimer and tetramer.
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26
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Yamada H, Motoyama A, Arai T, Ikeuchi K, Aki K, Wakamori S. α-Selective Glycosylation of 3,6-O-o-Xylylene-Bridged Glucosyl Fluoride. SYNTHESIS-STUTTGART 2018. [DOI: 10.1055/s-0037-1610841] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Yamada H, Wakamori S, Hirokane T, Ikeuchi K, Matsumoto S. Structural Revisions in Natural Ellagitannins. Molecules 2018; 23:E1901. [PMID: 30061530 PMCID: PMC6222896 DOI: 10.3390/molecules23081901] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2018] [Revised: 07/09/2018] [Accepted: 07/17/2018] [Indexed: 11/16/2022] Open
Abstract
Ellagitannins are literally a class of tannins. Triggered by the oxidation of the phenolic parts on β-pentagalloyl-d-glucose, ellagitannins are generated through various structural conversions, such as the coupling of the phenolic parts, oxidation to highly complex structures, and the formation of dimer and lager analogs, which expand the structural diversity. To date, more than 1000 natural ellagitannins have been identified. Since these phenolic compounds exhibit a variety of biological activities, ellagitannins have potential applications in medicine and health enhancement. Within the context of identifying suitable applications, considerations need to be based on correct structural features. This review describes the structural revisions of 32 natural ellagitannins, namely alnusiin; alnusnin A and B; castalagin; castalin; casuarinin; cercidinin A and B; chebulagic acid; chebulinic acid; corilagin; geraniin; isoterchebin; nobotanin B, C, E, G, H, I, J, and K; punicalagin; punicalin; punigluconin; roxbin B; sanguiin H-2, H-3, and H-6; stachyurin; terchebin; vescalagin; and vescalin. The major focus is on the outline of the initial structural determination, on the processes to find the errors in the structure, and on the methods for the revision of the structure.
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Affiliation(s)
- Hidetoshi Yamada
- School of Science and Technology, Kwansei Gakuin University, Sanda 669-1337, Japan.
| | - Shinnosuke Wakamori
- School of Science and Technology, Kwansei Gakuin University, Sanda 669-1337, Japan.
| | - Tsukasa Hirokane
- Faculty of Pharmaceutical Sciences, Tokushima Bunri University, Tokushima 770-8514, Japan.
| | - Kazutada Ikeuchi
- Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo 060-0810, Japan.
| | - Shintaro Matsumoto
- School of Science and Technology, Kwansei Gakuin University, Sanda 669-1337, Japan.
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29
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Kajimoto R, Nakamura M, Inamura Y, Kamazawa K, Ikeuchi K, Iida K, Ishikado M, Murai N, Kira H, Nakatani T, Ohira-Kawamura S, Takahashi R, Kubo N, Kambara W, Nakajima K, Aizawa K. Status report of the chopper spectrometer 4SEASONS. ACTA ACUST UNITED AC 2018. [DOI: 10.1088/1742-6596/1021/1/012030] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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30
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Ashibe S, Ikeuchi K, Kume Y, Wakamori S, Ueno Y, Iwashita T, Yamada H. Non-Enzymatic Oxidation of a Pentagalloylglucose Analogue into Members of the Ellagitannin Family. Angew Chem Int Ed Engl 2017. [DOI: 10.1002/ange.201708703] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Seiya Ashibe
- School of Science and Technology; Kwansei Gakuin University; 2-1 Gakuen Sanda 669-1337 Japan
| | - Kazutada Ikeuchi
- School of Science and Technology; Kwansei Gakuin University; 2-1 Gakuen Sanda 669-1337 Japan
| | - Yuji Kume
- School of Science and Technology; Kwansei Gakuin University; 2-1 Gakuen Sanda 669-1337 Japan
| | - Shinnosuke Wakamori
- School of Science and Technology; Kwansei Gakuin University; 2-1 Gakuen Sanda 669-1337 Japan
| | - Yuri Ueno
- School of Science and Technology; Kwansei Gakuin University; 2-1 Gakuen Sanda 669-1337 Japan
| | - Takashi Iwashita
- Bioorganic Research Institute; Suntory Foundation for Life Sciences; 8-1-1 Seikadai, Seika-cho Soraku-gun Kyoto 619-0284 Japan
| | - Hidetoshi Yamada
- School of Science and Technology; Kwansei Gakuin University; 2-1 Gakuen Sanda 669-1337 Japan
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31
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Ashibe S, Ikeuchi K, Kume Y, Wakamori S, Ueno Y, Iwashita T, Yamada H. Non-Enzymatic Oxidation of a Pentagalloylglucose Analogue into Members of the Ellagitannin Family. Angew Chem Int Ed Engl 2017; 56:15402-15406. [DOI: 10.1002/anie.201708703] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2017] [Revised: 10/01/2017] [Indexed: 11/08/2022]
Affiliation(s)
- Seiya Ashibe
- School of Science and Technology; Kwansei Gakuin University; 2-1 Gakuen Sanda 669-1337 Japan
| | - Kazutada Ikeuchi
- School of Science and Technology; Kwansei Gakuin University; 2-1 Gakuen Sanda 669-1337 Japan
| | - Yuji Kume
- School of Science and Technology; Kwansei Gakuin University; 2-1 Gakuen Sanda 669-1337 Japan
| | - Shinnosuke Wakamori
- School of Science and Technology; Kwansei Gakuin University; 2-1 Gakuen Sanda 669-1337 Japan
| | - Yuri Ueno
- School of Science and Technology; Kwansei Gakuin University; 2-1 Gakuen Sanda 669-1337 Japan
| | - Takashi Iwashita
- Bioorganic Research Institute; Suntory Foundation for Life Sciences; 8-1-1 Seikadai, Seika-cho Soraku-gun Kyoto 619-0284 Japan
| | - Hidetoshi Yamada
- School of Science and Technology; Kwansei Gakuin University; 2-1 Gakuen Sanda 669-1337 Japan
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32
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Yamada H, Motoyama A, Arai T, Ikeuchi K, Aki K, Wakamori S. α-Selective Glycosylation of 3,6-O-o-Xylylene-Bridged Glucosyl Fluoride. SYNTHESIS-STUTTGART 2017. [DOI: 10.1055/s-0036-1590927] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
A 1,2-cis-(α)-selective glycosylation has been developed. An ortho-xylylene group bridged between 3-O and 6-O of d-glucosyl fluoride, which straddles the β-face of the pyranose ring, hinders the approach of glycosyl acceptors from that face. The determination of the three-dimensional structure of the bridged glucosyl fluoride, the optimization process of the reaction conditions oriented toward kinetic control to realize the high α-selectivity, and the scope of the reaction are described.
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33
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Abstract
This account describes methods for synthesizing natural ellagitannins. The ellagitannins, a class of polyphenols, has a wide variety of chemical structures and biological activities. Here, we focus on three topics, which are the synthesis of the hexahydroxydiphenoyl group, construction of the hexahydroxydiphenoyl bridge, and synthesis of C–O digallates. The hexahydroxydiphenoyl group and the C–O digallates are C–C and C–O coupled galloyl groups, respectively, both group of which are the two major components of ellagitannins. By combining methods described in this account, many ellagitannins might be synthesized.
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Affiliation(s)
- Hidetoshi Yamada
- School of Science and Technology, Kwansei Gakuin University, Gakuen, Sanda 669-1337, Japan
| | - Tsukasa Hirokane
- Faculty of Pharmaceutical Sciences, Tokushima Bunri University, Yamashiro-cho, Tokushima 770-8514, Japan
| | - Kazutada Ikeuchi
- School of Science and Technology, Kwansei Gakuin University, Gakuen, Sanda 669-1337, Japan
| | - Shinnosuke Wakamori
- School of Science and Technology, Kwansei Gakuin University, Gakuen, Sanda 669-1337, Japan
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34
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Yamada H, Kaneko Y, Wakamori S, Ikeuchi K, Ohara K, Tanaka T. Total Synthesis of Lagerstannin C: Follow-up of the Khanbabaee’s Synthesis. SYNTHESIS-STUTTGART 2017. [DOI: 10.1055/s-0036-1588477] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
This report describes the total synthesis of lagerstannin C, a natural ellagitannin that has d-gluconic acid in the molecule. The study presented here is the first synthesis of the gluconic acid containing ellagitannin. The key step in the synthesis is the opening of δ-lactone through transesterification to form the corresponding benzyl ester.
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Affiliation(s)
| | - Yuki Kaneko
- School of Science and Technology, Kwansei Gakuin University
| | | | | | - Kenya Ohara
- School of Science and Technology, Kwansei Gakuin University
| | - Takashi Tanaka
- Graduate School of Biomedical Sciences, Nagasaki University
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35
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Horigane K, Kihou K, Fujita K, Kajimoto R, Ikeuchi K, Ji S, Akimitsu J, Lee CH. Spin excitations in hole-overdoped iron-based superconductors. Sci Rep 2016; 6:33303. [PMID: 27615691 PMCID: PMC5018845 DOI: 10.1038/srep33303] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2016] [Accepted: 08/24/2016] [Indexed: 11/16/2022] Open
Abstract
Understanding the overall features of magnetic excitation is essential for clarifying the mechanism of Cooper pair formation in iron-based superconductors. In particular, clarifying the relationship between magnetism and superconductivity is a central challenge because magnetism may play a key role in their exotic superconductivity. BaFe2As2 is one of ideal systems for such investigation because its superconductivity can be induced in several ways, allowing a comparative examination. Here we report a study on the spin fluctuations of the hole-overdoped iron-based superconductors Ba1-xKxFe2As2 (x = 0.5 and 1.0; Tc = 36 K and 3.4 K, respectively) over the entire Brillouin zone using inelastic neutron scattering. We find that their spin spectra consist of spin wave and chimney-like dispersions. The chimney-like dispersion can be attributed to the itinerant character of magnetism. The band width of the spin wave-like dispersion is almost constant from the non-doped to optimum-doped region, which is followed by a large reduction in the overdoped region. This suggests that the superconductivity is suppressed by the reduction of magnetic exchange couplings, indicating a strong relationship between magnetism and superconductivity in iron-based superconductors.
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Affiliation(s)
- K. Horigane
- Graduate School of Natural Science and Technology, Okayama University, Okayama 700-8530, Japan
| | - K. Kihou
- National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8568, Japan
| | - K. Fujita
- Aoyama Gakuin University, Sagamihara, Kanagawa 229-8558, Japan
| | - R. Kajimoto
- J-PARC Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195, Japan
| | | | - S. Ji
- Max Plank POSTECH Center for Complex Phase Materials, Pohang University of Science and Technology, Pohang 37673, Republic of Korea
| | - J. Akimitsu
- Research Center of New Functional Materials for Energy Production, Storage, and Transport, Okayama University, Okayama 700-8530, Japan
| | - C. H. Lee
- National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8568, Japan
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Ikeuchi K, Kobayashi Y, Suzuki K, Itoh M, Kajimoto R, Bourges P, Christianson AD, Nakamura H, Machida M, Sato M. Phonons of Fe-based superconductor Ca10Pt4As8(Fe1-x Pt x As)10. J Phys Condens Matter 2015; 27:465701. [PMID: 26510184 DOI: 10.1088/0953-8984/27/46/465701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We report the results of inelastic neutron scattering measurements on particular phonons of a superconducting (SC) Ca10Pt4As8(Fe1-x Pt x As)10 with the onset transition temperature T c ~ 33 K to investigate mainly what roles orbital fluctuation plays in Cooper pairing, where we observed a slight softening of the in-plane transverse acoustic mode corresponding to the elastic constant C 66. This softening starts at temperature T well above the SC T c, as T decreases. An anomalously strong change of the scattering intensity of in-plane optical modes was observed at the M point of the pseudo tetragonal reciprocal space in the range of 35 < ω < 40 meV with decreasing T from far above T c. Because this ω region mainly corresponds to the motion of Fe and As atoms in the FeAs planes, the finding presents information on the coupling between the orbital fluctuation of Fe 3d electrons and the lattice system, useful for studying the possible roles of orbital fluctuation in the pairing mechanism and/or the appearance of the so-called nematic phase.
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Affiliation(s)
- K Ikeuchi
- Research Center for Neutron Science and Technology, Comprehensive Research Organization for Science and Society (CROSS), Tokai, Ibaraki 319-1106, Japan
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Ishii K, Fujita M, Sasaki T, Minola M, Dellea G, Mazzoli C, Kummer K, Ghiringhelli G, Braicovich L, Tohyama T, Tsutsumi K, Sato K, Kajimoto R, Ikeuchi K, Yamada K, Yoshida M, Kurooka M, Mizuki J. High-energy spin and charge excitations in electron-doped copper oxide superconductors. Nat Commun 2014; 5:3714. [PMID: 24762677 DOI: 10.1038/ncomms4714] [Citation(s) in RCA: 84] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2013] [Accepted: 03/24/2014] [Indexed: 11/09/2022] Open
Abstract
The evolution of electronic (spin and charge) excitations upon carrier doping is an extremely important issue in superconducting layered cuprates and the knowledge of its asymmetry between electron- and hole-dopings is still fragmentary. Here we combine X-ray and neutron inelastic scattering measurements to track the doping dependence of both spin and charge excitations in electron-doped materials. Copper L3 resonant inelastic X-ray scattering spectra show that magnetic excitations shift to higher energy upon doping. Their dispersion becomes steeper near the magnetic zone centre and they deeply mix with charge excitations, indicating that electrons acquire a highly itinerant character in the doped metallic state. Moreover, above the magnetic excitations, an additional dispersing feature is observed near the Γ-point, and we ascribe it to particle-hole charge excitations. These properties are in stark contrast with the more localized spin excitations (paramagnons) recently observed in hole-doped compounds even at high doping levels.
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Affiliation(s)
- K Ishii
- SPring-8, Japan Atomic Energy Agency, Sayo, Hyogo 679-5148, Japan
| | - M Fujita
- Institute for Materials Research, Tohoku University, Katahira, Sendai 980-8577, Japan
| | - T Sasaki
- Institute for Materials Research, Tohoku University, Katahira, Sendai 980-8577, Japan
| | - M Minola
- CNR-SPIN and Dipartimento di Fisica, Politecnico di Milano, piazza Leonardo da Vinci 32, Milano I-20133, Italy
| | - G Dellea
- CNR-SPIN and Dipartimento di Fisica, Politecnico di Milano, piazza Leonardo da Vinci 32, Milano I-20133, Italy
| | - C Mazzoli
- CNR-SPIN and Dipartimento di Fisica, Politecnico di Milano, piazza Leonardo da Vinci 32, Milano I-20133, Italy
| | - K Kummer
- European Synchrotron Radiation Facility, 6 rue Jules Horowitz, Grenoble F-38043, France
| | - G Ghiringhelli
- CNR-SPIN and Dipartimento di Fisica, Politecnico di Milano, piazza Leonardo da Vinci 32, Milano I-20133, Italy
| | - L Braicovich
- CNR-SPIN and Dipartimento di Fisica, Politecnico di Milano, piazza Leonardo da Vinci 32, Milano I-20133, Italy
| | - T Tohyama
- 1] Yukawa Institute for Theoretical Physics, Kyoto University, Kyoto 606-8502, Japan [2]
| | - K Tsutsumi
- Institute for Materials Research, Tohoku University, Katahira, Sendai 980-8577, Japan
| | - K Sato
- Institute for Materials Research, Tohoku University, Katahira, Sendai 980-8577, Japan
| | - R Kajimoto
- Materials and Life Science Division, J-PARC Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195, Japan
| | - K Ikeuchi
- Research Center for Neutron Science and Technology, Comprehensive Research Organization for Science and Society, Tokai, Ibaraki 319-1106, Japan
| | - K Yamada
- Institute of Materials Structure Science, High Energy Accelerator Research Organization, Tsukuba, Ibaraki 305-0801, Japan
| | - M Yoshida
- 1] SPring-8, Japan Atomic Energy Agency, Sayo, Hyogo 679-5148, Japan [2] School of Science and Technology, Kwansei Gakuin University, Sanda, Hyogo 669-1337, Japan
| | - M Kurooka
- School of Science and Technology, Kwansei Gakuin University, Sanda, Hyogo 669-1337, Japan
| | - J Mizuki
- 1] SPring-8, Japan Atomic Energy Agency, Sayo, Hyogo 679-5148, Japan [2] School of Science and Technology, Kwansei Gakuin University, Sanda, Hyogo 669-1337, Japan
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Hirooka Y, Ikeuchi K, Kawamoto Y, Akao Y, Furuta T, Asakawa T, Inai M, Wakimoto T, Fukuyama T, Kan T. Enantioselective Synthesis of SB-203207. Org Lett 2014; 16:1646-9. [DOI: 10.1021/ol5002973] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Yasuo Hirooka
- School
of Pharmaceutical Sciences, University of Shizuoka and Global COE Program, 52-1 Yada, Suruga-ku, Shizuoka 422-8526, Japan
| | - Kazutada Ikeuchi
- School
of Pharmaceutical Sciences, University of Shizuoka and Global COE Program, 52-1 Yada, Suruga-ku, Shizuoka 422-8526, Japan
| | - Yuichiro Kawamoto
- Graduate
School of Pharmaceutical Sciences, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, Japan
| | - Yusuke Akao
- School
of Pharmaceutical Sciences, University of Shizuoka and Global COE Program, 52-1 Yada, Suruga-ku, Shizuoka 422-8526, Japan
| | - Takumi Furuta
- School
of Pharmaceutical Sciences, University of Shizuoka and Global COE Program, 52-1 Yada, Suruga-ku, Shizuoka 422-8526, Japan
- Institute
for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - Tomohiro Asakawa
- School
of Pharmaceutical Sciences, University of Shizuoka and Global COE Program, 52-1 Yada, Suruga-ku, Shizuoka 422-8526, Japan
| | - Makoto Inai
- School
of Pharmaceutical Sciences, University of Shizuoka and Global COE Program, 52-1 Yada, Suruga-ku, Shizuoka 422-8526, Japan
| | - Toshiyuki Wakimoto
- School
of Pharmaceutical Sciences, University of Shizuoka and Global COE Program, 52-1 Yada, Suruga-ku, Shizuoka 422-8526, Japan
- Graduate
School of Pharmaceutical Sciences, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, Japan
| | - Tohru Fukuyama
- Graduate
School of Pharmaceutical Sciences, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, Japan
- Graduate
School of Pharmaceutical Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan
| | - Toshiyuki Kan
- School
of Pharmaceutical Sciences, University of Shizuoka and Global COE Program, 52-1 Yada, Suruga-ku, Shizuoka 422-8526, Japan
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Ikeuchi K, Fujii R, Sugiyama S, Asakawa T, Inai M, Hamashima Y, Choi JH, Suzuki T, Kawagishi H, Kan T. Practical synthesis of natural plant-growth regulator 2-azahypoxanthine, its derivatives, and biotin-labeled probes. Org Biomol Chem 2014; 12:3813-5. [DOI: 10.1039/c4ob00705k] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
AHX derivatives and their probe molecules.
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Affiliation(s)
- Kazutada Ikeuchi
- School of Pharmaceutical Sciences
- University of Shizuoka
- Suruga-ku, Japan
| | - Ryosuke Fujii
- School of Pharmaceutical Sciences
- University of Shizuoka
- Suruga-ku, Japan
| | - Shimpei Sugiyama
- School of Pharmaceutical Sciences
- University of Shizuoka
- Suruga-ku, Japan
| | - Tomohiro Asakawa
- School of Pharmaceutical Sciences
- University of Shizuoka
- Suruga-ku, Japan
| | - Makoto Inai
- School of Pharmaceutical Sciences
- University of Shizuoka
- Suruga-ku, Japan
| | | | - Jae-Hoon Choi
- Research Institute of Green Science and Technology
- Shizuoka University
- Suruga-ku, Japan
| | - Tomohiro Suzuki
- Research Institute of Green Science and Technology
- Shizuoka University
- Suruga-ku, Japan
| | - Hirokazu Kawagishi
- Research Institute of Green Science and Technology
- Shizuoka University
- Suruga-ku, Japan
- Graduate School of Science and Technology
- Shizuoka University
| | - Toshiyuki Kan
- School of Pharmaceutical Sciences
- University of Shizuoka
- Suruga-ku, Japan
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Ikeuchi K, Hayashi M, Yamamoto T, Inai M, Asakawa T, Hamashima Y, Kan T. Stereocontrolled Total Synthesis of Sphingofungin E. European J Org Chem 2013. [DOI: 10.1002/ejoc.201301065] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Ikeuchi K, Ido S, Yoshimura S, Asakawa T, Inai M, Hamashima Y, Kan T. Catalytic desymmetrization of cyclohexadienes by asymmetric bromolactonization. Org Lett 2012; 14:6016-9. [PMID: 23148461 DOI: 10.1021/ol302908a] [Citation(s) in RCA: 108] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Asymmetric bromolactonization of prochiral cyclohexadiene derivatives with N-bromosuccimide proceeded in the presence of (DHQD)(2)PHAL as a chiral catalyst to afford the corresponding bromolactones with up to 93% ee. This reaction was also applicable to the kinetic resolution of a racemic cyclic ene-carboxylic acid, where the starting material was recovered with high enantioselectivity.
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Affiliation(s)
- Kazutada Ikeuchi
- School of Pharmaceutical Science, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka 422-8526, Japan
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Kan T, Sakai Y, Ikeuchi K, Yamada Y, Wakimoto T. Modified Julia-Kocienski Reaction Promoted by Means of m-NPT (Nitrophenyltetrazole) Sulfone. Synlett 2010. [DOI: 10.1055/s-0029-1219386] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Wakimoto S, Kimura H, Ishii K, Ikeuchi K, Adachi T, Fujita M, Kakurai K, Koike Y, Mizuki J, Noda Y, Yamada K, Said AH, Shvyd'ko Y. Charge excitations in the stripe-ordered La5/3Sr1/3NiO4 and La2-x(Ba,Sr)xCuO4 superconducting compounds. Phys Rev Lett 2009; 102:157001. [PMID: 19518667 DOI: 10.1103/physrevlett.102.157001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2008] [Indexed: 05/27/2023]
Abstract
Charge excitations in stripe-ordered 214 compounds La_{5/3}Sr_{1/3}NiO_{4} and 1/8-doped La2-x(Ba or Sr)xCuO4 are studied using resonant inelastic x-ray scattering in the hard x-ray regime. We observe = or approximately 1 eV excitation with a momentum transfer corresponding to the charge stripe spatial period both for the diagonal (nickelate) and parallel (cuprates) stripes. They are interpreted as collective stripe excitations or anomalous softening of the charge excitonic modes of the in-gap states.
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Affiliation(s)
- S Wakimoto
- Quantum Beam Science Directorate, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195, Japan.
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Ikeuchi K, Umesaki N. Factors affecting bone mineral density of young women and predictive factors of low bone mineral density. CLIN EXP OBSTET GYN 2009; 36:87-90. [PMID: 19688949] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
PURPOSE OF INVESTIGATION We investigated various factors affecting bone mineral density (BMD) in young women and predictive factors of low BMD. METHODS Subjects were 105 nursing school students aged from 19 to 24 years old. Body weight (BW), pituitary hormones, sex steroid hormone and bone turnover markers were selected as factors. BMD was measured at the lumbar spine at L2-L4 by dual-energy X-ray absorptiometry (DXA). RESULTS BW (p = 0.002), serum N-terminal telopeptide of type 1 collagen (NTx) (p = 0.006) and bone specific alkaline phosphatase (BAP) (p = 0.02) were significantly correlated with BMD. For identification of the low BMD group, all subjects were divided into four groups on the basis of BW and NTx concentrations. In the group with BW under 51 kg and Ntx concentrations over 11 nMBCE/1, BMD was significantly (p = 0.0013) decreased compared with the other three groups. In this group, the ratio of women with a low BMD was significantly higher (p = 0.004) than the other groups. CONCLUSION In young women, BW and bone turnover markers significantly affected BMD. Low BMD can be indicated using BW and NTx concentrations without measurement by DXA.
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Affiliation(s)
- K Ikeuchi
- School of Health and Nursing Science,Wakayama Medical University, Wakayama, Japan
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Ino Y, Oka T, Nomura K, Watanabe T, Kawashima S, Amano T, Hayashi Y, Okabe A, Uehara Y, Masuda T, Takamatsu J, Nakazawa A, Ikeuchi K, Endo H, Fukuta K, Akishinonomiya F. Breed differentiation among Japanese native chickens by specific skull features determined by direct measurements and computer vision techniques. Br Poult Sci 2008; 49:273-81. [PMID: 18568751 DOI: 10.1080/00071660802094727] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
1. Inter-breed morphological comparisons were made among 11 breeds of Japanese native chickens (Gifujidori, Hinaidori, Shokoku, Totenko, Tomaru, Satsumadori, Shamo, Koshamo, Koeyoshi, Chabo and Nagoya), White Leghorn, broiler chickens (Chunky) and red junglefowl collected in the Philippines, based on results of direct measurements and analysis by computer vision techniques of the skull. 2. Analysis of direct measurements identified two groups of chicken: a small type that included the Chabo, Koshamo, red junglefowl, Gifujidori and Shokoku and a large type that included the remaining breeds studied. These groupings were made based on size determined both in the first (PC1) and second principal component (PC2). The greatest length of the cranium and condylobasal length greatly contributed to the morphological differences between these two groups. 3. Analysis by computer vision techniques, however, identified three groups: the Bantam group (which includes red junglefowl), Shokoku group and Shamo group. White Leghorn clustered within the Shokoku group while the broiler chicken belonged to the Shamo group. The region around the junction of the neural cranium and the visceral cranium contributed greatly to the morphological differences among breeds, both in the PC1 and PC2.
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Affiliation(s)
- Y Ino
- Faculty of Agriculture, Tokyo University of Agriculture, Kanagawa, Japan
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Graf J, d'Astuto M, Jozwiak C, Garcia DR, Saini NL, Krisch M, Ikeuchi K, Baron AQR, Eisaki H, Lanzara A. Bond stretching phonon softening and kinks in the angle-resolved photoemission spectra of optimally doped Bi2Sr1.6La0.4Cu2O6+delta superconductors. Phys Rev Lett 2008; 100:227002. [PMID: 18643447 DOI: 10.1103/physrevlett.100.227002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2007] [Indexed: 05/26/2023]
Abstract
We report the first measurement of the Cu-O bond stretching phonon dispersion in optimally doped Bi2Sr1.6La0.4Cu2O6+delta using inelastic x-ray scattering. We found a softening of this phonon at q=( approximately 0.25,0,0) from 76 to 60 meV, similar to the one reported in other cuprates. A comparison with angle-resolved photoemission data on the same sample revealed an excellent agreement in terms of energy and momentum between the angle-resolved photoemission nodal kink and the soft part of the bond stretching phonon. Indeed, we find that the momentum space where a 63+/-5 meV kink is observed can be connected with a vector q=(xi,0,0) with xi > or =0.22, corresponding exactly to the soft part of the bond stretching phonon.
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Affiliation(s)
- J Graf
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
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Kuroki H, Nakagawa Y, Mori K, Kobayashi M, Yasura K, Okamoto Y, Mizuno Y, Ando K, Ikeuchi K, Nakamura T. Maturation-dependent change and regional variations in acoustic stiffness of rabbit articular cartilage: an examination of the superficial collagen-rich zone of cartilage. Osteoarthritis Cartilage 2006; 14:784-92. [PMID: 16563812 DOI: 10.1016/j.joca.2006.02.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/30/2005] [Accepted: 02/02/2006] [Indexed: 02/02/2023]
Abstract
OBJECTIVE The purpose of the study was to investigate maturation-dependent changes of acoustic (ultrasound) stiffness and other ultrasound features of articular cartilage in healthy rabbit knees. METHODS Five groups of rabbits of various ages (3 weeks, 8 weeks, 6 months, 1 year, 2.5 years) consisting of five rabbits per group were examined. Signal intensity (index of stiffness), signal duration (index of surface irregularity) and interval between signals (index of thickness) of the ultrasound reflection from articular cartilage were examined at four sites: posterior lateral femoral condyle, posterior medial femoral condyle, lateral tibial plateau, and medial tibial plateau. The sites were observed macroscopically and microscopically with a light microscope and a polarized light microscope. RESULTS At the lateral and medial condyles and the lateral tibial plateau, signal intensity was least in 3-week-old specimens. The intensity increased until 6 months or 1 year of age. At these sites, the signal durations and intervals between signals were least at the ages of 6 months or 1 year. At the medial tibial plateau, the intensity was the least at 2.5 years of age and the interval between signals was least at 3 weeks of age; there was no effect of age on signal duration. Cartilage surfaces of all specimens were smooth and no degenerative changes were macroscopically or microscopically evident. The surface brightness of cartilage under the polarized light microscope was consistent with signal intensity values. CONCLUSIONS The response of articular cartilage to ultrasound was maturation-dependent. Acoustic properties differed from mechanical stiffness properties, which were determined using indentation. Ultrasound may detect properties of the surface collagen of the articular cartilage.
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Affiliation(s)
- H Kuroki
- Department of Physical Therapy, School of Health Sciences, Faculty of Medicine, Kyoto University, 53 Kawahara-Cho, Shogoin, Sakyo-Ku, Kyoto, Japan
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Naka MH, Morita Y, Ikeuchi K. Influence of proteoglycan contents and of tissue hydration on the frictional characteristics of articular cartilage. Proc Inst Mech Eng H 2005; 219:175-82. [PMID: 15934393 DOI: 10.1243/095441105x34220] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
In this work, the hypothesis that water content and substances present on the articular surface play an important role in lubrication through the formation of a layer with a high content of water on the articular surface is analysed. The hydrophilic properties of proteoglycans exposed at the articular surface and hydration of tissue are the main responsible factors for the formation of this layer. The role of the articular surface in the frictional characteristics of articular cartilage was examined using specimens (femoral condyles of pigs) with intact and wiped surfaces tested in intermittent friction tests. Results indicated that the intact condition presented low friction in comparison with the wiped condition. The measured water loss of the articular cartilage after sliding and loading indicated a gradual decrease in the water content as the time evolved, and rehydration was observed after the submersion of unloaded specimens in the saline bath solution. Micrographic analyses indicated the presence of a layer covering the articular surface, and histological analyses indicated the presence of proteoglycans in this superficial layer. The hydration of the cartilage surface layer and proteoglycan in this layer influence lubrication.
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Affiliation(s)
- M H Naka
- Institute for Frontier Medical Sciences, Kyoto University, Kyoto, Japan.
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