Papers - Takao, Kenichi

Synthesis of Tetrahydro-β-carbolines via Cascade Sigmatropic Rearrangements

Oka D., Ohtsuka T., Takao K.i., Ogura A.

Advanced Synthesis and Catalysis 367 ( 3 )  2025.02

ISSN  16154150

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We have developed a synthesis for tetrahydro-β-carbolines involving cascade sigmatropic rearrangements. The substrates were conveniently prepared from parent anilines via a [2,3]-sigmatropic rearrangement and cyanomethylation. Silver-mediated decyanation afforded the corresponding iminium cation, which underwent a cascade consisting of an aza-Cope rearrangement, an aza-oxa-Cope rearrangement, an aromatization, and a Pictet-Spengler reaction, and tetrahydro-β-carbolines were obtained as the single product. The reaction involved seven bond scissions and four bond formations and was triggered by a single reagent.

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Synthetic Studies of Polycyclic Polyprenylated Acylphloroglucinols: Asymmetric Construction of a Cyclohexanone Moiety

Nanataki S., Aoki D., Onozawa H., Akiya T., Okuyama G., Abo K., Yoshida K., Ogura A., Takao K.I.

Synlett 36 ( 10 ) 1375 - 1378 2025

ISSN  09365214

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As a common intermediate for polycyclic polyprenylated acylphloroglucinols (PPAPs), we successfully synthesized a cyclohexanone moiety that contains two adjacent stereocenters, one of which is a quaternary carbon. Our synthetic strategy relied on an asymmetric Claisen rearrangement using Oppolzer's camphorsultam and a regioselective Dieckmann condensation.

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Antiproliferative activities through accelerating autophagic flux by basidalin and its analogs in human cancer cells

Matagawa T., Sasazawa Y., Agui K., Fujimaki M., Kawano S., Ogura A., Takao K.i., Igarashi M., Simizu S.

Bioorganic and Medicinal Chemistry Letters (Bioorganic and Medicinal Chemistry Letters)  104 2024.05

ISSN  0960894X

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Basidalin, isolated from the basidiomycete Leucoagaricus naucina, has previously demonstrated antibacterial and antitumor properties against murine cancer cells in vivo, but its effects on human cancer cells remain unknown. In this study, we found that basidalin possesses antiproliferative activity against human cancer cell lines. To elucidate the antiproliferative mechanism of basidalin, we focused on autophagy. Treatment with basidalin led to an increase in LC3-II expression level, and accelerated autophagic flux through an mTOR-independent pathway. Moreover, according to the structure–activity relationship analysis—including newly synthesized basidalin analogs—the formyl group, not the amino group, contributes to the antiproliferative activities of basidalin against human cancer cells. Additionally, the antiproliferative activity of basidalin analogs was strongly correlated with autophagy-inducing activity, indicating that basidalin exhibits antiproliferative activity through autophagy induction. These data suggest that basidalin, characterized by its ability to upregulate autophagic flux, emerges as a novel anticancer drug.

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Open system massive synthesis of narrow-band blue and green fluorescent graphene quantum dots and their application in water sensing

Ochi Y., Otani A., Katakami R., Ogura A., Takao K.I., Iso Y., Isobe T.

Journal of Materials Chemistry C (Journal of Materials Chemistry C)  12 ( 18 ) 6548 - 6558 2024.04

ISSN  20507526

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Graphene quantum dots (GQDs) are environmentally friendly fluorescent carbon-based nanomaterials. However, there is no report on the massive synthesis of GQDs with narrow-band fluorescence and a high photoluminescence quantum yield (PLQY) using a simple liquid-phase method under atmospheric conditions. In this study, GQDs were successfully synthesized in ∼100% product yield by heating phloroglucinol (PG) with Na3PO4·12H2O in 1,2-pentanediol at 180 °C for 6 h in an open system with air flow, followed by dialysis purification. The high product yield was attributed to the addition of Na3PO4·12H2O as a base catalyst, which promoted the dehydration-condensation reaction between PG molecules. The dispersion of PG derived GQDs (PG-GQDs) in ethanol resulted in blue fluorescence with a full width at half maximum of 32 nm and a PLQY of 54%. Further purification of PG-GQDs by silica gel column chromatography improved the PLQY to 75%. Fourier-transform infrared spectroscopy, 1H nuclear magnetic resonance spectroscopy, and X-ray photoelectron spectroscopy confirmed that dehydration-condensation reactions occurred not only between PGs but also between GQDs and 1,2-pentanediol. The binding of 1,2-pentanediol to the edges of GQDs suppressed the stacking of GQDs and prevented concentration quenching, resulting in a high PLQY. PG-GQDs exhibited negative fluorescence solvatochromism, i.e., the fluorescence wavelength blue-shifted with increasing solvent polarity. Dispersion of PG-GQDs in N-methyl-2-pyrrolidone (MP) resulted in green fluorescence with a PLQY of 96%. Dispersion of PG-GQDs in water resulted in blue fluorescence and a low PLQY of 6% at pH 7, while the PLQY was more than 50% at pH ≥ 11. Using these properties, the sensing of water (pH 13) in MP was investigated. The results showed that as the water content was increased from 0% to 100%, the fluorescence color gradually changed from green to blue and the fluorescence wavelength continuously shifted from 514 nm to 466 nm, indicating their applicability in water sensing.

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Red-light-mediated Barton decarboxylation reaction and one-pot wavelength-selective transformations

Yamamoto H., Yamaoka K., Shinohara A., Shibata K., Takao K.I., Ogura A.

Chemical Science (Chemical Science)  14 ( 40 ) 11243 - 11250 2023.09

ISSN  20416520

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In organic chemistry, selecting mild conditions for transformations and saving energy are increasingly important for achieving sustainable development goals. Herein, we describe a red-light-mediated Barton decarboxylation using readily available red-light-emitting diodes as the energy source and zinc tetraphenylporphyrin as the catalyst, avoiding explosive or hazardous reagents or external heating. Mechanistic studies suggest that the reaction probably proceeds via Dexter energy transfer between the activated catalyst and the Barton ester. Furthermore, a one-pot wavelength-selective reaction within the visible light range is developed in combination with a blue-light-mediated photoredox reaction, demonstrating the compatibility of two photochemical transformations based on mechanistic differences. This one-pot process expands the limits of the decarboxylative Giese reaction beyond polarity matching.

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Open system synthesis of narrow-bandwidth red-fluorescent carbon quantum dots with a function of multi-metal ion sensing

Katakami R., Sato K., Ogura A., Takao K.I., Iso Y., Isobe T.

Journal of Materials Chemistry C (Journal of Materials Chemistry C)  11 ( 12 ) 4143 - 4152 2023.03

ISSN  2050-7526

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Carbon quantum dots (CQDs) are environmentally friendly phosphors. However, there have been few reports on red-emitting CQDs with narrow-bandwidths, all of which were synthesized via solvothermal methods using autoclaves. Here, red-emitting CQDs were synthesized from 4,6-diaminoresorcinol dihydrochloride (DAR), which is an aromatic compound with electron-donating hydroxy and amino groups. The synthesis involved heating at 180 °C for 6 h in a high-boiling-point 1,2-pentanediol solvent in an open system without using autoclaves and catalysts. The DAR-derived-CQDs in ethanol exhibited red photoluminescence with a 0.14 eV full width at half-maximum that was comparable to that of narrow-bandwidth blue-fluorescent phloroglucinol (PG)-derived-CQDs. The red emission was attributed to a weakened quantum-size effect and electron-donating NH2 groups. The hydroxy groups of PG-derived-CQDs interacted with Al3+ and Fe3+ ions, resulting in fluorescence quenching. DAR-derived-CQDs have hydroxy and amino groups, which facilitate the fluorescence quenching for Al3+, Fe3+, Cu2+, and Pb2+ ions.

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Synthesis of Indoles via Sigmatropic Rearrangements and Olefin Isomerization

Uchida T., Saito R., Takao K.i., Ogura A.

Advanced Synthesis and Catalysis (Advanced Synthesis and Catalysis)  366 ( 3 ) 465 - 472 2023

ISSN  16154150

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Indoles are important heterocycles in pharmaceuticals and agrochemicals, and their atom-economical synthesis is needed. Herein, we describe the synthesis of indoles using sigmatropic rearrangements. The N-allylaniline was oxidized by environmentally benign hydrogen peroxide, and spontaneous [2,3]-Meisenheimer rearrangement gave N-allyloxyaniline. Subsequent treatment with a ruthenium catalyst afforded N-vinyloxyaniline, which underwent [3,3]-sigmatropic rearrangement to give indoles, expelling water as the only byproduct. The whole sequence is free of quantitative salt byproducts, thereby avoiding aqueous work up and cutting off the inorganic waste.

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Asymmetric Synthesis of Cyclopentene Compounds Containing All-Carbon Quaternary Stereocenters by (3 + 2) Cycloaddition and Its Application in the Formal Synthesis of (R)-(-)-Puraquinonic Acid

Oga M., Takamatsu Y., Ogura A., Takao K.I.

Journal of Organic Chemistry (Journal of Organic Chemistry)  87 ( 13 ) 8788 - 8795 2022.07

ISSN  00223263

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A highly stereoselective (3 + 2) cycloaddition for the asymmetric synthesis of versatile cyclopentene compounds containing all-carbon quaternary stereocenters was developed. The phosphine-catalyzed reactions of alkynoates with α-alkylated electron-deficient alkenes bearing Oppolzer's camphorsultam showed high to excellent diastereoselectivities and perfect regioselectivities. The usefulness of this reaction was demonstrated in the concise formal synthesis of (R)-(-)-puraquinonic acid.

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Elucidation of structure-activity relationship of humulanolides and identification of humulanolide analog as a novel HSP90 inhibitor

Saegusa J., Osada Y., Miura K., Sasazawa Y., Ogura A., Takao K.i., Simizu S.

Bioorganic and Medicinal Chemistry Letters (Bioorganic and Medicinal Chemistry Letters)  60 2022.03

ISSN  0960894X

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Humulanolides are natural products isolated from Asteriscus, and the isolation and total synthesis of many types of humulanolides have been reported. In this study, we evaluated anti-proliferative activity of twelve humulanolides against various human cancer cell lines and found that humulanolide analog E, which was newly designed and synthesized, exhibited the highest anti-proliferative activity. Structure-activity relationship analysis revealed that α,β-unsaturated carbonyl moieties in humulanolides play an important role for anti-proliferative activity. To identify molecular targets of humulanolide analog E, we investigated various cell-based and in vitro assays. Treatment with humulanolide analog E against human fibrosarcoma HT1080 cells increased the expression level of HSP70 protein and decreased the levels of AKT and CDK4, which are HSP90 client proteins. Moreover, humulanolide analog E inhibited refolding of denatured luciferase protein via suppression of HSP90 activity in vitro. These results suggest that humulanolide analog E possesses the anti-proliferative activity against human cancer cells by inhibiting HSP90 functions.

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Development of TfOH-Catalyzed Spirocyclization by Intramolecular Friedel-Crafts-type 1,4-Addition: Application to the Total Synthesis of the Unusual Proaporphine Alkaloid (±)-Misrametine

Yoshida K., Hidaka A., Fukami Y., Fujino Y., Imaizumi Y., Takao K.i., Kitagaki S.

Chemistry - A European Journal (Chemistry - A European Journal)  28 ( 60 )  2022

ISSN  09476539

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An effective method was developed for TfOH-catalyzed construction of spiroindanes and spirotetralines containing an all-carbon quaternary stereocenter. Intramolecular Friedel-Crafts-type 1,4-addition of the substrates which were di- or trimethoxybenzene and 2-cyclohexenone linked by an alkyl chain proceeded smoothly in the presence of 30 mol % of TfOH. A variety of spiroindanes and spirotetralines were obtained with moderate to excellent yield by this method. The reaction was successfully applied in the first total synthesis of the unusual proaporphine alkaloid (±)-misrametine, which included the gram-scale spirocyclization and selective O-demethylation used KCN in DMSO condition as key steps.

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Asymmetric Diels–Alder reaction between furans and propiolates

Ogura A., Ito T., Moriya K., Horigome H., Takao K.i.

Tetrahedron Letters (Tetrahedron Letters)  72 2021.05

ISSN  00404039

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We report the first asymmetric Diels–Alder reaction between furan and propiolates. Propiolate, a dienophile, was equipped with an Evans’ auxiliary and a sulfonyl group to control and facilitate diastereoselective cycloaddition. Treatment with furan as a diene and aluminium Lewis acid afforded a 7-oxabicyclo[2.2.1]heptadiene skeleton diastereoselectively. The origin of diastereoselectivity can be explained by chelation of aluminium center to carbonyl groups and oxygen of furan. Friedel–Crafts-type products were obtained when pyrrole was used as diene.

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Glycothermally Synthesized Carbon Dots with Narrow-Bandwidth and Color-Tunable Solvatochromic Fluorescence for Wide-Color-Gamut Displays

Yoshinaga T., Shinoda M., Iso Y., Isobe T., Ogura A., Takao K.I.

ACS Omega (ACS Omega)  6 ( 2 ) 1741 - 1750 2021.01

ISSN  2470-1343

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Fluorescent carbon dots (CDs) represent a promising eco-friendly next-generation phosphor. However, most CDs exhibit broad photoluminescence (PL) spectra [full width at half-maximum (fwhm) over 60 nm]; few works on CDs with sharp PL spectra (fwhm less than 40 nm) have been reported. In addition, their syntheses and color tuning require harsh conditions of high temperatures, long reaction times, and high pressures with catalysts. Here, we successfully prepared narrow-bandwidth emissive CDs (fwhm of 27-40 nm) from phloroglucinol in a glycol solvent of 1,2-pentanediol at temperatures as low as 180 °C for a reaction duration of as short as 6 h under ambient conditions without any catalysts via an open reaction system in which dehydration and condensation reactions among phloroglucinol molecules were enhanced. We shifted the emission peak from 463 to 511 nm by selecting seven kinds of solvents with different polarities, that is, emission colors could be tuned from blue to green by taking advantage of fluorescence solvatochromism. The CD-dispersed polymer films showed a similar solvatochromic behavior and sharp PL spectra, verifying the feasibility of applying the CDs to displays with a wide color gamut.

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Diaryliodonium Salt-Based Synthesis of N-Alkoxyindolines and Further Insights into the Ishikawa Indole Synthesis

Shibata K., Takao K.I., Ogura A.

Journal of Organic Chemistry (Journal of Organic Chemistry)  86 ( 15 ) 10067 - 10087 2021

ISSN  00223263

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A diaryliodonium salt-based strategy enabled the first systematic synthesis of rarely accessible N-alkoxyindoles. Mechanistic analyses suggested that the reaction likely involves reductive elimination of iodobenzene from iodaoxazepine via a four-membered transition state, followed by Meisenheimer rearrangement. Substrates with N-carbamate protection afforded indole in a manner similar to that of the Ishikawa indole synthesis. Preinstallation of a stannyl group as an iodonium salt precursor greatly expanded the substrate scope, and further mechanistic insights are discussed.

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The stereoselective construction of all-carbon quaternary stereocenters by allylations and its application to synthetic studies of natural products

Sakama A., Ogura A., Yoshida K., Takao K.I.

Yuki Gosei Kagaku Kyokaishi/Journal of Synthetic Organic Chemistry (Yuki Gosei Kagaku Kyokaishi/Journal of Synthetic Organic Chemistry)  78 ( 11 ) 1039 - 1047 2020.11

ISSN  00379980

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© 2020 Society of Synthetic Organic Chemistry. All rights reserved. The synthesis of organic compounds containing all.. carbon quaternary stereocenters through the addition of allylmetals to aldehydes is still a challenge. In this account we describe two methods to achieve this transformation stereoselectively: One involves the zinc-mediated Barbier-type allylation and the other allylboration of a sugar.. derived aldehyde. These methods were applied to the total synthesis of (+)-vibsanin A, and the synthesis of the tricyclic core of (-)-callophycoic acid A.

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Enantioselective Organocatalytic Construction of Spirochroman Derivatives

Yoshida K., Inoue H., Oji Y., Suzuki H., Takao K.I.

Journal of Organic Chemistry (Journal of Organic Chemistry)  85 ( 15 ) 10189 - 10197 2020.08

ISSN  00223263

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Copyright © 2020 American Chemical Society. Highly enantioselective organocatalytic construction of spirochromans containing a tetrasubstituted stereocenter was developed. Intramolecular oxy-Michael addition was catalyzed with a bifunctional cinchona alkaloid thiourea catalyst. A variety of spirochroman compounds containing a tetrasubstituted stereocenter were obtained with excellent enantioselectivities of up to 99% enantiomeric excess. The reaction was applied to the asymmetric formal synthesis of (-)-(R)-cordiachromene.

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Red-Light-Mediated Barton-McCombie Reaction

Ogura Akihiro, Ichii Naoki, Shibata Kouhei, Takao Ken-ichi

BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN (Bulletin of the Chemical Society of Japan)  93 ( 7 ) 936 - 941 2020.07

ISSN  0009-2673

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© 2020 Chemical Society of Japan. All rights reserved. A red-light-mediated BartonMcCombie reaction is described, in which chlorophyll a is used as a photocatalyst and tris(trimethylsilyl)silane or Hantzsch ester is used as the hydrogen source. The reaction can be performed with a set of easily available equipment and reagents, and a variety of linear and cyclic xanthates could be applied. In contrast to the traditional conditions, the reaction does not involve toxic organotin or an explosive radical initiator. The reaction mechanism was analyzed both by experiments and computation, and it was suggested that the radical chain mechanism initiated by excitation of complex followed by charge transfer is likely to be operative.

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Total Synthesis of Natural Products Using Intramolecular Nozaki-Hiyama-Takai-Kishi Reactions

Takao K.I., Ogura A., Yoshida K., Simizu S.

Synlett (Synlett)  31 ( 5 ) 421 - 433 2020.03

ISSN  09365214

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© 2020 Georg Thieme Verlag. All rights reserved. In this Account, we describe our studies on the total synthesis of several natural products using intramolecular Nozaki-Hiyama-Takai-Kishi (NHTK) reactions. In each synthesis, an NHTK reaction is used to efficiently construct a medium-sized ring. These examples demonstrate the utility of the intramolecular NHTK reaction in natural product synthesis. 1 Introduction 2 Total Synthesis of (+)-Pestalotiopsin A 3 Total Synthesis of (+)-Cytosporolide A 4 Total Synthesis of (+)-Vibsanin A 5 Total Syntheses of (+)-Aquatolide and Related Humulanolides 6 Conclusion.

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Stereoselective Synthesis of the Tricyclic Core of (-)-Callophycoic Acid A

Sakama A., Kameshima R., Motohashi Y., Sumida W., Unno Y., Yoshida K., Ogura A., Takao K.I.

Journal of Organic Chemistry (Journal of Organic Chemistry)  85 ( 5 ) 3245 - 3264 2020.03

ISSN  00223263

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Copyright © 2020 American Chemical Society. Two stereocontrolled routes to the tricyclic core of (-)-callophycoic acid A are described. Our synthetic strategy relied on stereoselective allylboration using a new allylboronate reagent to construct the all-carbon quaternary stereocenter in the core, followed by efficient radical cyclization or palladium-catalyzed reductive cyclization to form its multisubstituted cyclohexane ring. The tetrahydrooxepin ring was constructed by intramolecular etheration. This study provides the first method for the stereoselective synthesis of the characteristic tricyclic skeleton of callophycoic acids.

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Identification of vibsanin A analog as a novel HSP90 inhibitor

Miura K., Matsuki W., Ogura A., Takao K., Simizu S.

Bioorganic and Medicinal Chemistry (Bioorganic and Medicinal Chemistry)  28 ( 2 )  2020.01

ISSN  09680896

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© 2019 Elsevier Ltd Vibsanin A is the first natural product isolated from Viburnum awabuki and has several biological activities. We have reported that a vibsanin A analog, obtained from process of total synthesis of vibsanin A, has anti-proliferative activity against human cancer cell lines. In this study, we evaluated anti-proliferative effect of the vibsanin A analogs against various human cancer cell lines and examined molecular target of the analog in human cells. Among the vibsanin A analogs, vibsanin A analog C (VAC) showed anti-proliferative effect against various cancer cell lines, and the anti-proliferative activity was strongest among the vibsanin A analogs. Additionally, VAC fluctuated amounts of HSP90-related proteins in cells and inhibited HSP90-mediated protein refolding of luciferase in vitro. These results suggest that the anti-proliferative activity of VAC is due to HSP90 inhibition, and VAC has a potential as novel anti-cancer drug as HSP90 inhibitor.

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Recent advances in the total synthesis of clavilactones

Ogura A., Takao K.I.

Heterocycles (Heterocycles)  100 ( 9 ) 1355 - 1370 2020

ISSN  03855414

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© 2020 The Japan Institute of Heterocyclic Chemistry – Clavilactones are meroterpenoids containing a 10-membered carbocycle fused to an α,β-epoxy-γ-lactone and a hydroquinone or benzoquinone. This review describes the total synthesis of clavilactones achieved by four research groups, focusing on their innovative synthetic strategies.

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Total Syntheses of (+)-Aquatolide and Related Humulanolides

Takao K., Kai H., Yamada A., Fukushima Y., Komatsu D., Ogura A., Yoshida K.

Angewandte Chemie - International Edition (Angewandte Chemie - International Edition)  58 ( 29 ) 9851 - 9855 2019

ISSN  14337851

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© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim The short, efficient total synthesis of (+)-aquatolide was achieved by a biomimetic transannular [2+2] photocycloaddition, and provides the first example of constructing a 5/5/4/8-ring system from asteriscunolides. Furthermore, the reaction leading to a 5/4/4/7-ring system, the originally proposed structure of aquatolide, was also developed. This strategy achieved syntheses of five more humulanolides, (−)-asteriscunolides A, C, D, and I, and (+)-tetradehydroasteriscanolide.

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Identification of topoisomerases as molecular targets of cytosporolide C and its analog

Otake K., Yamada K., Miura K., Sasazawa Y., Miyazaki S., Niwa Y., Ogura A., Takao K., Simizu S.

Bioorganic and Medicinal Chemistry (Bioorganic and Medicinal Chemistry)  27 ( 15 ) 3334 - 3338 2019

ISSN  09680896

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© 2019 Elsevier Ltd Cytosporolide (Cytos) A–C, isolated from the fungus Cytospora sp., have anti-microbial activity, but their molecular targets in mammalian cells are unknown. We have previously reported the total synthesis of Cytos A by biomimetic hetero-Diels-Alder reaction. In this study, to examine the novel bioactivity of Cytos, we synthesized Cytos C and measured cell growth-inhibiting activities of 7 compounds, including Cytos A and C, in several human cancer cell lines. Among these compounds, Cytos C and tetradeoxycytosporolide A (TD-Cytos A), a model compound for the synthesis of Cytos A, had anti-proliferative effects on cancer cells, and TD-Cytos A exhibited stronger activity than Cytos C. In vitro topoisomerase-mediated DNA relaxing experiments showed that TD-Cytos A inhibited the activities of topoisomerase I and II, whereas Cytos C targeted only topoisomerase I. These data suggest that the anti-proliferative activities of Cytos correlate with the inhibition of topoisomerases and implicated TD-Cytos A as a novel anti-cancer drug that suppresses the activities of topoisomerase I and II.

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Studies toward the synthesis of perforatumone: Synthesis of the 7-OXABICYCLO[4.2.1]NONANE-8,9-DIONE CORE

Nakajima T., Takiguchi K., Yoshida K., Ogura A., Takao K.

Heterocycles (Heterocycles)  99 ( 1 ) 661 - 668 2019

ISSN  03855414

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© 2019 The Japan Institute of Heterocyclic Chemistry. Construction of the unique bridged bicyclic skeleton, 7-oxabicyclo[4.2.1]nonane-8,9-dione, of perforatumone was achieved. Key steps included a Dieckmann-type condensation, a Claisen rearrangement, and an intramolecular Michael reaction.

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Enantioselective Total Synthesis of (-)-Misramine

Yoshida K., Fujino Y., Takamatsu Y., Matsui K., Ogura A., Fukami Y., Kitagaki S., Takao K.

Organic Letters (Organic Letters)  20 ( 16 ) 5044 - 5047 2018.08

ISSN  15237060

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© 2018 American Chemical Society. The enantioselective total synthesis of an unusual pentacyclic proaporphine alkaloid, (-)-misramine, was achieved. The synthetic strategy relied on an enantioselective intramolecular Friedel-Crafts-type 1,4-addition using an asymmetric organocatalyst to construct a spiroindane skeleton containing an all-carbon quaternary stereocenter and a double reductive amination of the keto-aldehyde to form a piperidine ring toward the end of the synthesis. This work is the first example of asymmetric synthesis of a proaporphine alkaloid.

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Total Synthesis of Clavilactones

Ken-ichi Takao, Kento Mori, Kenya Kasuga, Ryuki Nanamiya, Ayumi Namba, Yuuki Fukushima, Ryuichi Nemoto, Takuma Mogi, Hiroyuki Yasui, Akihiro Ogura, Keisuke Yoshida, and Kin-ichi Tadano

J. Org. Chem. (Journal of Organic Chemistry)  Vol.83 ( 13 ) 7060 - 7075 2018.07

Research paper (scientific journal), Joint Work, Accepted,  ISSN  00223263

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Copyright © 2018 American Chemical Society. Clavilactones A, B, and D are epidermal growth factor receptor tyrosine kinase inhibitors that were isolated from cultures of the fungus Clitocybe clavipes. Here, we report full details of the total synthesis of these clavilactones. A key feature of our synthetic approach is a ring-opening/ring-closing metathesis strategy that allows the concise transformation of a cyclobutenecarboxylate into a γ-butenolide. Coupled with enantioselective Ti/BINOL-catalyzed alkynylation of a multisubstituted benzaldehyde and ring-closing metathesis of a diene-bearing silylene acetal to construct the 10-membered carbocycle, this strategy enabled the total synthesis of the natural enantiomers (+)-clavilactone A and (-)-clavilactone B. In addition, the correct structure of clavilactone D was determined by the synthesis of two newly proposed structures. This research resulted in the asymmetric synthesis of the revised (+)-clavilactone D.

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Synthesis and Evaluation of Biological Activities of Vibsanin A Analogs

Wataru Matsuki, So Miyazaki, Keisuke Yoshida, Akihiro Ogura, Yukiko Sasazawa, Ken-ichi Takao, and Siro Simizu

Bioorg. Med. Chem. Lett. Vol.27   4536 - 4539 2017.10

Research paper (scientific journal), Joint Work, Accepted

Total Synthesis and Structural Revision of Clavilactone D

Ken-ichi Takao, Ryuichi Nemoto, Kento Mori, Ayumi Namba, Keisuke Yoshida, and Akihiro Ogura

Chem. Eur. J. Vol.23   3828 - 3831 2017.03

Research paper (scientific journal), Joint Work, Accepted

Kinetically Controlled α-Selective O-Glycosylation of Phenol Derivatives Using 2-Nitroglycals by a Bifunctional Chiral Thiourea Catalyst

Keisuke Yoshida, Yohei Kanoko, and Ken-ichi Takao

Asian J. Org. Chem. Vol.5   1230 - 1236 2016.10

Research paper (scientific journal), Joint Work, Accepted

Stereoselective Construction of All-Carbon Quaternary Stereocenters by Allylboration of Chiral Aldehydes: Synthesis of a Fragment of (+)-Vibsanin A

Akihiro Sakama, Yoshiyasu Nishimura, Yuko Motohashi, Keisuke Yoshida, and Ken-ichi Takao

Tetrahedron Vol.72   5465 - 5471 2016.09

Research paper (scientific journal), Joint Work, Accepted

Enantioselective Organocatalytic Construction of Spiroindane Derivatives by Intramolecular Friedel–Crafts-type 1,4-Addition

Keisuke Yoshida, Yukihiro Itatsu, Yuta Fujino, Hiroki Inoue, and Ken-ichi Takao

Angew. Chem. Int. Ed. Vol.55   6734 - 6738 2016.06

Research paper (scientific journal), Joint Work, Accepted

Organocatalytic Regioselective Chlorosilylation of Oxirane Derivatives: Mild and Effective Insertion of Bulky Silyl Chloride by Using 4-Methoxypyridine N-Oxide

Keisuke Yoshida, Hina Suzuki, Hiroki Inoue, Kohei Matsui, Yuta Fujino, Yohei Kanoko, Yukihiro Itatsu, and Ken-ichi Takao

Adv. Synth. Catal. Vol.358   1886 - 1891 2016.06

Research paper (scientific journal), Joint Work, Accepted

Identification of a seco-clavilactone B as a small-molecule actin polymerization inhibitor

So Miyazaki, Yukiko Sasazawa, Takuma Mogi, Takehiro Suzuki, Keisuke Yoshida, Naoshi Dohmae, Ken-ichi Takao, and Siro Simizu

FEBS Lett. Vol.590   1163 - 1173 2016.04

Research paper (scientific journal), Joint Work, Accepted

Amine-Free Silylation of Alcohols under 4-Methylpyridine N-Oxide-Catalyzed Conditions

Keisuke Yoshida, Yuta Fujino, Yukihiro Itatsu, Hiroki Inoue, Yohei Kanoko, and Ken-ichi Takao

Tetrahedron Lett. Vol.57   627 - 631 2016.02

Research paper (scientific journal), Joint Work, Accepted

連続オレフィンメタセシス反応を用いた天然物の全合成

高尾賢一・吉田圭佑・只野金一

有機合成化学協会誌 Vol.73   1192 - 1199 2015.12

Research paper (scientific journal), Joint Work, Accepted

Total Synthesis of (+)-Cytosporolide A via a Biomimetic Hetero-Diels–Alder Reaction

Ken-ichi Takao, Shuji Noguchi, Shu Sakamoto, Mizuki Kimura, Keisuke Yoshida, and Kin-ichi Tadano

J. Am. Chem. Soc. Vol.137   15971 - 15977 2015.12

Research paper (scientific journal), Joint Work, Accepted

Total Synthesis of (+)-Vibsanin A

Ken-ichi Takao, Kohei Tsunoda, Takuya Kurisu, Akihiro Sakama, Yoshiyasu Nishimura, Keisuke Yoshida, and Kin-ichi Tadano

Org. Lett. Vol.17   756 - 759 2015.02

Research paper (scientific journal), Joint Work, Accepted

An Access to the 13-Membered Cyclophane Substructure in GKK1032As: An Intramolecular 1,4-Addition Approach

Satoka Nagai, Yuka Yamagishi, Yuta Shimizu, Ken-ichi Takao, and Kin-ichi Tadano

Heterocycles Vol.90   819 - 826 2015.01

Research paper (scientific journal), Joint Work, Accepted

Catalytic Silylation of Secondary Alcohols by Pyridine N-Oxide Derivative

Keisuke Yoshida and Ken-ichi Takao

Tetrahedron Lett. Vol.55   6861 - 6863 2014.12

Research paper (scientific journal), Joint Work, Accepted

Total Synthesis of (+)-Clavilactone A and (–)-Clavilactone B by Ring-Opening/Ring-Closing Metathesis

Ken-ichi Takao, Ryuki Nanamiya, Yuuki Fukushima, Ayumi Namba, Keisuke Yoshida, and Kin-ichi Tadano

Org. Lett. Vol.15   5582-5585 2013.11

Research paper (scientific journal), Joint Work, Accepted

Synthetic Studies of the Spirocyclic Cyclohexene Part of Versipelostatin, a Novel GRP78/Bip Molecular Chaperone Downregulator

Shu Sasaki, Suguru Samejima, Tomoki Uruga, Kai Anzai, Natsumi Nishi, Eriko Kawakita, Ken-ichi Takao, and Kin-ichi Tadano

J. Antibiot. Vol.66   147-154 2013.03

Research paper (scientific journal), Joint Work, Accepted

Construction of All-Carbon Quaternary Stereocenters by Zinc-Mediated Barbier-Type Allylation in Aqueous Media

Ken-ichi Takao, Tomo Miyashita, Nozomi Akiyama, Takuya Kurisu, Kohei Tsunoda, and Kin-ichi Tadano

Heterocycles Vol.86   147-153 2012.12

Research paper (scientific journal), Joint Work, Accepted

Asymmetric Construction of All-Carbon Quaternary Stereocenters by Chiral-Auxiliary- Mediated Claisen Rearrangement and Total Synthesis of (+)-Bakuchiol

Ken-ichi Takao, Shu Sakamoto, Marianne Ayaka Touati, Yusuke Kusakawa, and Kin-ichi Tadano

Molecules Vol.17   13330-13344 2012.11

Research paper (scientific journal), Joint Work, Accepted

Determination of the Absolute Structure of (+)-Akaterpin

Hayato Hosoi, Nobuyuki Kawai, Hideki Hagiwara, Takahiro Suzuki, Atsuo Nakazaki, Ken-ichi Takao, Kazuo Umezawa, and Susumu Kobayashi

Chem. Pharm. Bull. Vol.60   137-143 2012.01

Research paper (scientific journal), Joint Work, Accepted

糖質由来のキラルテンプレートを用いた立体選択的炭素-炭素結合形成反応の開発

戸谷希一郎・高尾賢一・只野金一

有機合成化学協会誌 Vol.69   1363-1374 2011.12

Research paper (scientific journal), Joint Work, Accepted

Synthesis and Determination of the Relative Structure of Akaterpin, a Potent Inhibitor of PI-PLC

Hayato Hosoi, Nobuyuki Kawai, Hideki Hagiwara, Takahiro Suzuki, Atsuo Nakazaki, Ken-ichi Takao, Kazuo Umezawa, and Susumu Kobayashi

Tetrahedron Lett. Vol.52   4961-4964 2011.09

Research paper (scientific journal), Joint Work, Accepted

Total Syntheses of (+)-Spiculoic Acid A and (+)-Zyggomphic Acid, New Marine Natural Products of Polyketide Origin

Daisuke Matsumura, Toshimasa Takarabe, Takumi Toda, Takashi Hayamizu, Kiyoto Sawamura, Ken-ichi Takao, and Kin-ichi Tadano

Tetrahedron Vol.67   6730-6745 2011.09

Research paper (scientific journal), Joint Work, Accepted

Synthesis of Nitrogen- and Oxygen-Bridged Seven- to Ten-Membered Carbocycles Using Metathesis Reactions

Ken-ichi Takao and Kin-ichi Tadano

Heterocycles Vol.81   1603-1629 2010.07

Research paper (scientific journal), Joint Work, Accepted

Total Syntheses of (+)- and (–)-Pestalotiopsin A

Ken-ichi Takao, Nobuhiko Hayakawa, Reo Yamada, Taro Yamaguchi, Hiroshi Saegusa, Masatoshi Uchida, Suguru Samejima, and Kin-ichi Tadano

J. Org. Chem. Vol.74   6452-6461 2009.09

Research paper (scientific journal), Joint Work, Accepted

Total Synthesis of (+)-Spiculoic Acid A

Daisuke Matsumura, Takumi Toda, Takashi Hayamizu, Kiyoto Sawamura, Ken-ichi Takao, and Kin-ichi Tadano

Tetrahedron Lett. Vol.50   3356-3358 2009.07

Research paper (scientific journal), Joint Work, Accepted

Stereoselective α-Alkylation of Methyl 6-Deoxy-3,4-di-O-(tert-butyldimethylsilyl)-2-O-(2-methyl-3-oxobutanoyl)-α-D-glucopyranoside

Yoko Akashi, Ken-ichi Takao, and Kin-ichi Tadano

Tetrahedron Lett. Vol.50   1139-1142 2009.03

Research paper (scientific journal), Joint Work, Accepted

Total Synthesis of (–)-Norzoanthamine

Daisuke Yamashita, Yoshihisa Murata, Naotsuka Hikage, Ken-ichi Takao, Atsuo Nakazaki, and Susumu Kobayashi

Angew. Chem. Int. Ed. Vol.48   1404-1406 2009.02

Research paper (scientific journal), Joint Work, Accepted

Enantioselective Synthesis of a 3,5,5-Trialkylated Tetronic Acid Derivative

Ken-ichi Takao, Yuki Kojima, Tomo Miyashita, Kentaro Yashiro, Tatsuya Yamada, and Kin-ichi Tadano

Heterocycles Vol.77   167-172 2009.01

Research paper (scientific journal), Joint Work, Accepted

Total Synthesis of (–)-Pestalotiopsin A

Ken-ichi Takao, Nobuhiko Hayakawa, Reo Yamada, Taro Yamaguchi, Urara Morita, Soujiro Kawasaki, and Kin-ichi Tadano

Angew. Chem. Int. Ed. Vol.47   3426-3429 2008.04

Research paper (scientific journal), Joint Work, Accepted

Stereoselective Synthesis of Highly Enantioenriched 3-Methyl-2-cyclohexen-1-ones Possessing an Asymmetric Quaternary Carbon as C-4 or C-6: A Sugar Template Approach

Hiroto Kubo, Ikuko Kozawa, Ken-ichi Takao, and Kin-ichi Tadano

Tetrahedron Lett. Vol.49   1203-1207 2008.02

Research paper (scientific journal), Joint Work, Accepted

Formal Synthesis of Tubelactomicins via a Transannular Diels–Alder Approach

Toshimi Anzo, Akari Suzuki, Kiyoto Sawamura, Toru Motozaki, Madoka Hatta, Ken-ichi Takao, and Kin-ichi Tadano

Tetrahedron Lett. Vol.48   8442-8448 2007.11

Research paper (scientific journal), Joint Work, Accepted

Total Syntheses of Natural Tubelactomicins B, D, and E: Establishment of Their Stereochemistries

Kiyoto Sawamura, Keigo Yoshida, Akari Suzuki, Toru Motozaki, Ikuko Kozawa, Takashi Hayamizu, Ryosuke Munakata, Ken-ichi Takao, and Kin-ichi Tadano

J. Org. Chem. Vol.72   6143-6148 2007.08

Research paper (scientific journal), Joint Work, Accepted

特異な構造を持つγ−ラクタム型天然有機化合物の全合成

高尾賢一・青木伸也・只野金一

有機合成化学協会誌 Vol.65   460-469 2007.05

Research paper (scientific journal), Joint Work, Accepted

Stereoselective Mannich-like Reactions of Ester Enolates Generated on Sugar-Templates: A Novel Access to A Key Intermediate for 1β-Methyl Carbapenem Synthesis

Daisuke Sasaki, Daisuke Sawamoto, Ken-ichi Takao, Kin-ichi Tadano, Masayuki Okue, and Kei-ichi Ajito

Heterocycles Vol.72   103-110 2007.04

Research paper (scientific journal), Joint Work, Accepted

Stereoselective Double Alkylation of the Acetoacetate Ester α-Carbon on a D-Glucose-Derived Template: Application to the Synthesis of Enantiopure Cycloalkenones Bearing an Asymmetric Quaternary Carbon

Ikuko Kozawa, Yoko Akashi, Kumiko Takiguchi, Daisuke Sasaki, Daisuke Sawamoto, Ken-ichi Takao, and Kin-ichi Tadano

Synlett    399-402 2007.02

Research paper (scientific journal), Joint Work, Accepted

Synthetic Studies toward Clavilactone A: A Concise Access to α,γ-Substituted γ-Butenolides by Metathesis

Hiroyuki Yasui, Shun Yamamoto, Ken-ichi Takao, and Kin-ichi Tadano

Heterocycles Vol.70   135-141 2006.12

Research paper (scientific journal), Joint Work, Accepted

Total Synthesis of (–)-Pramanicin

Shi-ya, Aoki, Taro Tsukude, Yukari Miyazaki, Ken-ichi Takao, and Kin-ichi Tadano

Heterocycles Vol.69   49-54 2006.12

Research paper (scientific journal), Joint Work, Accepted

Total Syntheses of (+)-1893B and Its Three Diastereomers and Evaluation of Their Biological Activities

Hiroyuki Yasui, Kunihiro Hirai, Shun Yamamoto, Ken-ichi Takao, and Kin-ichi Tadano

J. Antibiot. Vol.59   456-463 2006.08

Research paper (scientific journal), Joint Work, Accepted

Total Synthesis of (+)-1893B Aimed at Establishing its Stereochemistry

Hiroyuki Yasui, Kunihiro Hirai, Shun Yamamoto, Ken-ichi Takao, and Kin-ichi Tadano

Heterocycles Vol.67   123-128 2006.01

Research paper (scientific journal), Joint Work, Accepted

Recent Advances in Natural Product Synthesis by Using Intramolecular Diels-Alder Reactions

Ken-ichi Takao, Ryosuke Munakata, and Kin-ichi Tadano

Chem. Rev. Vol.105   4779-4807 2005.12

Research paper (scientific journal), Joint Work, Accepted

Synthetic Studies of Pestalotiopsin A: Asymmetric Synthesis of the 2-Oxabicyclo[3.2.0]heptane Substructure

Ken-ichi Takao, Hiroshi Saegusa, Tomohiro Tsujita, Takenori Washizawa, and Kin-ichi Tadano

Tetrahedron Lett. Vol.46   5815-5818 2005.08

Research paper (scientific journal), Joint Work, Accepted

Total Synthesis of (+)-Tubelactomicin A (Part 2): Synthesis of the Upper-Half Segment and the Completion of the Total Synthesis

Toru Motozaki, Kiyoto Sawamura, Akari Suzuki, Keigo Yoshida, Tatsuo Ueki, Aiko Ohara, Ryosuke Munakata, Ken-ichi Takao, and Kin-ichi Tadano

Org. Lett. Vol.7   2265-2267 2005.05

Research paper (scientific journal), Joint Work, Accepted

Total Synthesis of (+)-Tubelactomicin A (Part 1): Stereoselective Synthesis of the Lower-Half Segment by an Intramolecular Diels-Alder Approach

Toru Motozaki, Kiyoto Sawamura, Akari Suzuki, Keigo Yoshida, Tatsuo Ueki, Aiko Ohara, Ryosuke Munakata, Ken-ichi Takao, and Kin-ichi Tadano

Org. Lett. Vol.7   2261-2264 2005.05

Research paper (scientific journal), Joint Work, Accepted

Asymmetric Total Syntheses of (+)-Mycoepoxydiene and Related Natural Product (-)-1893A: Application of One-Pot Ring-Opening/Cross/Ring-Closing Metathesis to Construct their 9-Oxabicyclo[4.2.1]nona-2,4-diene Skeleton

Ken-ichi Takao, Hiroyuki Yasui, Shun Yamamoto, Daisuke Sasaki, Soujiro Kawasaki, Gohshi Watanabe, and Kin-ichi Tadano

J. Org. Chem. Vol.69   8789-8795 2004.12

Research paper (scientific journal), Joint Work, Accepted

Sugar as a Tool for Asymmetric Synthesis: Some Effective Approaches

Kiichiro Totani, Ken-ichi Takao, and Kin-ichi Tadano

Synlett    2066-2080 2004.10

Research paper (scientific journal), Joint Work, Accepted

Total Syntheses of Natural Pseurotins A, F2, and Azaspirene

Shin-ya Aoki, Takahiro Oi, Kazuya Shimizu, Ryota Shiraki, Ken-ichi Takao, and Kin-ichi Tadano

Bull. Chem. Soc. Jpn. Vol.77   1703-1716 2004.09

Research paper (scientific journal), Joint Work, Accepted

Total Synthesis of Macquarimicins Using an Intramolecular Diels-Alder Approach Inspired by a Biosynthetic Pathway

Ryosuke Munakata, Hironori Katakai, Tatsuo Ueki, Jun Kurosaka, Ken-ichi Takao, and Kin-ichi Tadano

J. Am. Chem. Soc. Vol.126   11254-11267 2004.09

Research paper (scientific journal), Joint Work, Accepted

効率よい天然有機化合物の合成

高尾賢一・只野金一

化学工業 Vol.55   359-364 2004.05

Research paper (scientific journal), Joint Work

Total Syntheses of Natural Pseurotins A and F2 and Azaspirene

Shin-ya Aoki, Takahiro Oi, Kazuya Shimizu, Ryota Shiraki, Ken-ichi Takao, and Kin-ichi Tadano

Heterocycles Vol.62   161-166 2004.01

Research paper (scientific journal), Joint Work, Accepted

Total Synthesis of (+)-Macquarimicin A

Ryosuke Munakata, Hironori Katakai, Tatsuo Ueki, Jun Kurosaka, Ken-ichi Takao, and Kin-ichi Tadano

J. Am. Chem. Soc. Vol.125   14722-14723 2003.12

Research paper (scientific journal), Joint Work, Accepted

A Convergent Total Synthesis of Epolactaene: an Application of the Bridgehead Oxiranyl Anion Strategy

Kouji Kuramochi, Seigo Nagata, Hideyoshi Itaya, Yasuaki Matsubara, Takashi Sunoki, Hiromi Uchiro, Ken-ichi Takao, and Susumu Kobayashi

Tetrahedron Vol.59   9743-9758 2003.12

Research paper (scientific journal), Joint Work, Accepted

Highly Stereoselective 1,4-Addition of the Enolate Generated from 6-Deoxy-D-Glucopyranoside-Derived Propionyl Ester to Methyl Crotonate: Application to Total Synthesis of (-)-Lasiol

Shingo Asano, Testuo Tamai, Kiichiro Totani, Ken-ichi Takao, and Kin-ichi Tadano

Synlett    2252-2254 2003.11

Research paper (scientific journal), Joint Work, Accepted

Highly Stereoselective [3+2] Cycloadditions of Nitrile Oxides to Methyl 4-O-Acryloyl-6-deoxy-2,3-O-(t-butyldimethylsilyl)-a-D-glucopyranoside

Testuo Tamai, Shingo Asano, Kiichiro Totani, Ken-ichi Takao, and Kin-ichi Tadano

Synlett    1865-1867 2003.10

Research paper (scientific journal), Joint Work, Accepted

Clerocidin Alkylates DNA through its Epoxide Function: Evidence for a Fine Tuned Mechanism of Action

Sara Richter, Barbara Gatto, Daniele Fabris, Ken-ichi Takao, Susumu Kobayashi, and Manlio Palumbo

Nucleic Acids Res. Vol.31   5149-5156 2003.09

Research paper (scientific journal), Joint Work, Accepted

Stereocontrolled Synthesis of a Highly Functionalized 1,7-Dioxaspiro[4.4]nonane Derivative Related to Antibiotic Pseurotins

Shin-ya Aoki, Takahiro Ohi, Kazuya Shimizu, Ryota Shiraki, Ken-ichi Takao, and Kin-ichi Tadano

Heterocycles Vol.58   57-61 2002.11

Research paper (scientific journal), Joint Work, Accepted

Asymmetric Total Syntheses of (+)-Cheimonophyllon E and (+)-Cheimonophyllal

Ken-ichi Takao, Tomohiro Tsujita, Manabu Hara, and Kin-ichi Tadano

J. Org. Chem. Vol.67   6690-6698 2002.09

Research paper (scientific journal), Joint Work, Accepted

Total Synthesis of (+/-)-Mycoepoxydiene, a Novel Oxygen-Bridged Cyclooctadiene Fungal Metabolite

Ken-ichi Takao, Gohshi Watanabe, Hiroyuki Yasui, and Kin-ichi Tadano

Org. Lett. Vol.4   2941-2943 2002.08

Research paper (scientific journal), Joint Work, Accepted

分子内Diels-Alder反応を利用した最近の天然有機化合物の全合成

鈴木芳和・村田　毅・高尾賢一・只野金一

有機合成化学協会誌 Vol.60   679-690 2002.07

Research paper (scientific journal), Joint Work, Accepted

Syntheses and Absolute Stereochemistries of UPA0043 and UPA0044, Cytotoxic Antibiotics Having a p-Quinone-methide Structure

Ken-ichi Takao, Tomoko Sasaki, Tomohito Kozaki, Yumiko Yanagisawa, Kin-ichi Tadano, Akira Kawashima, Hideki Shinonaga

Org. Lett. Vol.3   4291-4294 2001.12

Research paper (scientific journal), Joint Work, Accepted

Highly Diastereoselective Diels-Alder Reactions of Acrylic Esters Incorporated into a Variety of Hexopyranosides

Takayuki Nagatsuka, Shuhei Yamaguchi, Kiichiro Totani, Ken-ichi Takao, Kin-ichi Tadano

J. Carbohydr. Chem. Vol.20   519-535 2001.12

Research paper (scientific journal), Joint Work, Accepted

Highly Stereoselective a-Alkylations, 1,4-Additions, and One-pot 1,4-Addition/a-Methylations Achieved on 4-O-Acyl and 4-O-Crotonyl Derivatives of Methyl 6-Deoxy-2,3-di-O-(t-butyldimethylsilyl)-a-D-glucopyranoside

Kiichiro Totani, Shingo Asano, Ken-ichi Takao, Kin-ichi Tadano

Synlett    1772-1776 2001.11

Research paper (scientific journal), Joint Work, Accepted

Synthetic Study of Macquarimicins: Highly Stereoselective Construction of the AB-Ring System

Ryosuke Munakata, Tatsuo Ueki, Hironori Katakai, Ken-ichi Takao, Kin-ichi Tadano

Org. Lett. Vol.3   3029-3032 2001.09

Research paper (scientific journal), Joint Work, Accepted

Highly Diastereoselective 1,4-Addition of an Organocuprate to Methyl a-D-Gluco, a-D-Manno-, or a-D-Galactopyranosides Tethering an a,b-Unsaturated Ester. Novel Asymmetric Access to b-C-Substituted Butanoic Acids

Kiichiro Totani, Takayuki Nagatsuka, Shuhei Yamaguchi, Ken-ichi Takao, Shigeru Ohba, Kin-ichi Tadano

J. Org. Chem. Vol.66   5965-5975 2001.09

Research paper (scientific journal), Joint Work, Accepted

Total Synthesis of (-)-Mniopetal F, a Novel Inhibitor of RNA-directed DNA-polymerases

Yoshikazu Suzuki, Aiko Ohara, Kenji Sugaya, Ken-ichi Takao, Kin-ichi Tadano

Tetrahedron Vol.57   7291-7301 2001.08

Research paper (scientific journal), Joint Work, Accepted

Preparation and Properties of Thermosensitive Hydrogel Microcapsules

Kimiko Makino, Yohei Fujita, Ken-ichi Takao, Susumu Kobayashi, Hiroyuki Ohshima

Colloids Surf. B Vol.21   259-263 2001.08

Research paper (scientific journal), Joint Work, Accepted

Total Synthesis of (+)-Cheimonophyllon E, a Bisabolane Sesquiterpenoid

Ken-ichi Takao, Manabu Hara, Tomohiro Tsujita, Ken-ichi Yoshida, Kin-ichi Tadano

Tetrahedron Lett. Vol.42   4665-4668 2001.07

Research paper (scientific journal), Joint Work, Accepted

Highly Stereoselective Diels-Alder Reactions Achieved on Some Hexopyranosidic Templates

Takayuki Nagatsuka, Shuhei Yamaguchi, Kiichiro Totani, Ken-ichi Takao, Kin-ichi Tadano

Synlett    481-484 2001.04

Research paper (scientific journal), Joint Work, Accepted

Orthoester Claisen Rearrangement of a D-Glucose-derived Spirocyclic Substrate

Ken-ichi Takao, Hiroshi Saegusa, Kin-ichi Tadano

J. Carbohydr. Chem. Vol. 20   57-69 2001.02

Research paper (scientific journal), Joint Work, Accepted

Total Synthesis of (-)-Mniopetal E, a Novel Biologically Intriguing Drimane Sesquiterpenoid

Yoshikazu Suzuki, Ryoko Nishimaki, Makoto Ishikawa, Takeshi Murata, Ken-ichi Takao, Kin-ichi Tadano

J. Org. Chem. Vol. 65   8595-8607 2000.12

Research paper (scientific journal), Joint Work, Accepted

Synthetic Studies of Zoanthamine/Norzoanthamine: Biogenetic-like One-Step Construction of the Heterocyclic Aminal Core (CDEFG Ring) from a Monocyclic Precursor

Naotsuka Hikage, Hironori Furukawa, Ken-ichi Takao, Susumu Kobayashi

Chem. Pharm. Bull. Vol. 48   1370-1372 2000.09

Research paper (scientific journal), Joint Work, Accepted

Synthesis of a Potential Key Intermediate of Akaterpin, Specific Inhibitor of PI-PLC

Nobuyuki Kawai, Yoko Fujibayashi, Seiya Kuwabara, Ken-ichi Takao, Yasuharu Ijuin, Susumu Kobayashi

Tetrahedron Vol. 56   6467-6478 2000.09

Research paper (scientific journal), Joint Work, Accepted

Highly Stereoselective Lewis Acid Mediated Conjugate Radical Additions to Methyl a-D-Glucopyranoside Derivatives Tethering an Unsaturated Ester Moiety at C-4

Ryosuke Munakata, Kiichiro Totani, Ken-ichi Takao, Kin-ichi Tadano

Synlett    979-982 2000.07

Research paper (scientific journal), Joint Work, Accepted

Synthesis of an Enantiomeric 2,5-Di-(E)-propenyltetrahydrofuran-3,4-diol Derivative

Eiju Suzuki, Ken-ichi Takao, Kin-ichi Tadano

Heterocycles Vol.52   519-523 2000.02

Research paper (scientific journal), Joint Work, Accepted

Stereoselective Carbon-carbon Bond Forming Reaction of Chiral Cyclopent-2-enone and Cyclopentene-1-methanol, both Spiro-connecting a 1,2:5,6-Di-O-isopropylidene-a-D-glucofuranosyl Ring

Ken-ichi Takao, Hiroshi Saegusa, Gohshi Watanabe, Kin-ichi Tadano

Tetrahedron: Asymmetry Vol.11   453-464 2000.02

Research paper (scientific journal), Joint Work, Accepted

Highly Stereoselective 1,4-Conjugate Addition of Organocopper Reagents to Methyl a-D-Glucopyranoside Derivatives Tethering an Unsaturated Ester Moiety at C-4 or C-6

Kiichiro Totani, Takayuki Nagatsuka, Ken-ichi Takao, Shigeru Ohba, Kin-ichi Tadano

Org. Lett. Vol.1   1447-1450 1999.11

Research paper (scientific journal), Joint Work, Accepted

Total Synthesis of (-)-Mniopetal E, a Novel Biologically Intriguing Drimane Sesquiterpenoid

Yoshikazu Suzuki, Ryoko Nishimaki, Makoto Ishikawa, Takeshi Murata, Ken-ichi Takao, Kin-ichi Tadano

Tetrahedron Lett. Vol.40   7835-7838 1999.10

Research paper (scientific journal), Joint Work, Accepted

Generation and Reaction of an Oxiranyl Anion Derived from a.b-Epoxy-g-butyrolactone

Kouji Kuramochi, Hideyoshi Itaya, Seigo Nagata, Ken-ichi Takao, Susumu Kobayashi

Tetrahedron Lett. Vol.40   7367-7370 1999.10

Research paper (scientific journal), Joint Work, Accepted

Convergent Total Synthesis of Epolactaene: Application of Bridgehead Oxiranyl Anion Strategy

Kouji Kuramochi, Seigo Nagata, Hideyoshi Itaya, Ken-ichi Takao, Susumu Kobayashi

Tetrahedron Lett. Vol.40   7371-7374 1999.10

Research paper (scientific journal), Joint Work, Accepted

Synthetic Study of Akaterpin: Determination of the Relative Stereochemistry of the Upper Decalin Moiety with Disulfated Hydroquinone

Nobuyuki Kawai, Ken-ichi Takao, Susumu Kobayashi

Tetrahedron Lett. Vol.40   4193-4196 1999.05

Research paper (scientific journal), Joint Work, Accepted

Biological Activities of 1,1,6-Trisubstituted Indanes: Beyond Magainin 2

Naganori Numao, Yukiko Hirota, Akiyo Iwahori, Shun-ichi Kidokoro, Masanori Sasatsu, Isamu Kondo, Sachiko Itoh, Etsuko Itoh, Tadashi Katoh, Noriko Shimozono, Akiko Yamazaki, Ken-ichi Takao, and Susumu Kobayashi

Biol. Pharm. Bull. Vol.22   73-75 1999.01

Research paper (scientific journal), Joint Work, Accepted

D-グルコースを出発物質としたセスキテルペノイド類の合成研究ー(+)-エレマントリドAと(-)-ベルカロールの全合成ー

高尾賢一，石原　淳，只野金一

有機合成化学協会誌 Vol.56   1026-1035 1998.12

Research paper (scientific journal), Joint Work, Accepted

Synthetic Studies of Zoanthamine/Norzoanthamine Alkaloids: Construction of the Heterocyclic Aminal Core (CDEFG Ring)

Naotsuka Hikage, Hironori Furukawa, Ken-ichi Takao, and Susumu Kobayashi

Tetrahedron Lett. Vol.39   6241-6244 1998.08

Research paper (scientific journal), Joint Work, Accepted

Glycosyl 2-Pyridinecarboxylate as an Effective Glycosyl Donor: Glycosidation of Mannose, 2-Azidosugar, and 2-Deoxysugar into Disaccharides

Hironori Furukawa, Kazunori Koide, Ken-ichi Takao, and Susumu Kobayashi

Chem. Pharm. Bull. Vol.46   1244-1247 1998.08

Research paper (scientific journal), Joint Work, Accepted

Synthetic Studies of Zoanthamine/Norzoanthamine Alkaloids: Advanced Intermediate for the Heterocyclic Aminal Core

Naotsuka Hikage, Hironori Furukawa, Ken-ichi Takao, and Susumu Kobayashi

Tetrahedron Lett. Vol.39   6237-6240 1998.08

Research paper (scientific journal), Joint Work, Accepted

Model Study for the Total Synthesis of Antifungal Australifungin: Construction of a-Diketone and b-Ketoaldehyde Moieties

Ken-ichi Takao, Seigo Nagata, Susumu Kobayashi, Hisanaka Ito, and Takeo Taguchi

Chem. Lett.    447-448 1998.05

Research paper (scientific journal), Joint Work, Accepted

Structurally Simplified Zaragozic Acid (Squalestatin): Stereoselective Preparation of a 3,4-Unsubstituted Derivative

Hisanaka Ito, Miyoko Matsumoto, Takeshi Yoshizawa, Ken-ichi Takao, and Susumu Kobayashi

Tetrahedron Lett. Vol.38   9009-9012 1997.12

Research paper (scientific journal), Joint Work, Accepted

Antibacteral Activity of (+/-)-6-Benzyl-1-(3-carboxypropyl)-indane; A Possible Way to Identify Leading Novel Anti-H. pylori Agents

Naganori Numao, Yukiko Hirota, Akiyo Iwahori, Masanori Sasatsu, Isamu Kondo, Ken-ichi Takao, and Susumu Kobayashi

Biol. Pharm. Bull. Vol.20   1204-1207 1997.11

Research paper (scientific journal), Joint Work, Accepted

Synthetic Study on Antitumor Antibiotic Terpentecin: Construction of the Carbobicyclic Decalin Moiety

Ken-ichi Takao and Susumu Kobayashi

Tetrahedron Lett. Vol.38   6685-6688 1997.09

Research paper (scientific journal), Joint Work, Accepted

Synthesis of 2-O-(3-O-Carbamoyl-a-D-mannopyranosyl)-L-gulopyranose: Sugar Moiety of Antitumor Antibiotic Bleomycin

Tetsuta Oshitari, Masakatsu Shibasaki, Takeshi Yoshizawa, Ken-ichi Takao, and Susumu Kobayashi

Tetrahedron Vol.53   10993-11006 1997.08

Research paper (scientific journal), Joint Work, Accepted

Stereoselective Route to the Highly Oxidated Sidechain Moiety of Terpentecin and Related Antibiotics

Ken-ichi Takao, Yasuyuki Aiba, Hisanaka Ito, and Susumu Kobayashi

Chem. Lett.    931-932 1996.11

Research paper (scientific journal), Joint Work, Accepted

Enantioselective Synthesis of Curacin A. 2. Total Synthesis of Curacin A by Condensation of C1-C7, C8-C17, and C18-C22 Segments

Hisanaka Ito, Nobuyuki Imai, Ken-ichi Takao, and Susumu Kobayashi

Tetrahedron Lett. Vol.37   1799-1800 1996.03

Research paper (scientific journal), Joint Work, Accepted

Novel Total Synthesis of (+)-Eremantholide A

Ken-ichi Takao, Hiroshi Ochiai, Ken-ichi Yoshida, Takahiko Hashizuka, Hirokazu Koshimura, Kin-ichi Tadano, and Seiichiro Ogawa

J. Org. Chem. Vol.60   8179-8193 1995.12

Research paper (scientific journal), Joint Work, Accepted

A Total Synthesis of (+)-Eremantholide A

Ken-ichi Takao, Hiroshi Ochiai, Takahiko Hashizuka, Hirokazu Koshimura, Kin-ichi Tadano, and Seiichiro Ogawa

Tetrahedron Lett. Vol.36   1487-1490 1995.02

Research paper (scientific journal), Joint Work, Accepted

Stereoselective Total Syntheses of (-)-Desoxoprosopinine and (-)-Desoxoprosophylline: Palladium(0)-Catalyzed Intramolecular N-Alkylation for the Key Piperidine Ring Formation

Ken-ichi Takao, Yuya Nigawara, Emiko Nishino, Izumi Takagi, Koji Maeda, Kin-ichi Tadano, and Seiichiro Ogawa

Tetrahedron Vol.50   5681-5704 1994.05

Research paper (scientific journal), Joint Work, Accepted

Stereoselective Total Syntheses of (-)-Desoxoprosopinine and (-)-Desoxoprosophylline: Palladium(0)-Catalyzed Intramolecular N-Alkylation for the Key Piperidine Ring Formation

Kin-ichi Tadano, Ken-ichi Takao, Yuya Nigawara, Emiko Nishino, Izumi Takagi, Koji Maeda, and Seiichiro Ogawa

Synlett    565-567 1993.08

Research paper (scientific journal), Joint Work, Accepted

Intramolecular Aldol Condensation Applied to D-Glucose-derived d-Ketoaldehydes

Kin-ichi Tadano, Satoshi Kanazawa, Ken-ichi Takao, and Seiichiro Ogawa

Tetrahedron Vol.48   4283-4300 1992.05

Research paper (scientific journal), Joint Work, Accepted