研究者詳細 - 五東　弘昭

Structure-antioxidant activity (oxygen radical absorbance capacity) relationships of phenolic compounds

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：{MDPI} {AG} 共著

<jats:p>Radioactivity was measured in a micellar gel dosimeter, a polymer gel dosimeter, and water was irradiated by carbon ion beams at various beam energy conditions. Monte Carlo simulation was also performed to estimate the radioactivity. Short-lived positron-emitting nuclides were observed immediately after irradiation, but they decayed rapidly into the background. At 24 h post-irradiation, the dominant measured radioactivity was of 7Be. The simulation also showed minor activity of 24Na and 3H; however, they were not experimentally observed. The measured radioactivity was independent of the type of gel dosimeter under all irradiation conditions, suggesting that the radioactivity was induced by the interaction of carbon ions with water (the main component of the gel dosimeters). The ratio between the simulated and measured radioactivity was within 0.9–1.5. The activity concentration of 7Be was found to be less than 1/10 of the value derived using the exemption concept proposed by the International Atomic Energy Agency. This result should be applicable to irradiated gel dosimeters containing mainly water and 0–4 wt.% C and 0–1.7 wt.% N.</jats:p>

Sakurai Shuhei, Kawakami Yuta, Kuroki Manabu, Gotoh Hiroaki

STRUCTURAL CHEMISTRY 33 ( 4 ) 1055 - 1062 2022年3月 [査読有り]

Mechanism for the photodegradation of 9,10-dibutoxyanthracene in the presence of air

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Springer Science and Business Media {LLC} 共著

Ryotaro Seto, Arisa Sato, Keita Iuchi, Shunichi Himori, Hiroaki Gotoh

PLoS One 17 ( 3 ) e0263526 2022年3月 [査読有り]

Hydrophilic oxygen radical absorbance capacity values of low-molecular-weight phenolic compounds containing carbon, hydrogen, and oxygen

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Public Library of Science (PLoS) 共著

<jats:p>The photoreactivity of anthracene has been previously verified for a range of its derivatives. 9,10-Dibutoxyanthracene is commonly used as an electron transfer sensitizer for photopolymerization because of its favorable optical properties. This study experimentally demonstrated that 9,10-dibutoxyanthracene produces an endoperoxide species upon reaction with the oxygen present in air. A secondary decomposition product formed during the photodecomposition of the endoperoxide species was also isolated and identified. The proposed reaction pathway is supported by singlet oxygen scavenger studies and calculations of the singlet–triplet transition energies. Our findings suggest that 9,10-dibutoxyanthracene can be used as a photo-induced oxygen scavenger.</jats:p>

Sakurai Shuhei, Kikuchi Akito, Gotoh Hiroaki

RSC ADVANCES 12 ( 7 ) 4094 - 4100 2022年1月 [査読有り]

Prediction and Chemical Interpretation of Singlet-Oxygen-Scavenging Activity of Small Molecule Compounds by Using Machine Learning

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Royal Society of Chemistry (RSC) 共著

<jats:p>The hydrophilic oxygen radical absorbance capacity (H-OARC) assay measures the antioxidant capacity of compounds against the peroxyl radical, a reactive oxygen species.</jats:p>

Taiki Fujimoto, Hiroaki Gotoh

Antioxidants 10 ( 11 ) 1751 2021年11月 [査読有り]

Behaviour and mechanism of micelle gel dosimeter for carbon-ion-beam irradiation

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：MDPI AG 共著

<jats:p>A chemically explainable machine learning model was constructed with a small dataset to quantitatively predict the singlet-oxygen-scavenging ability. In this model, ensemble learning based on decision trees resulted in high accuracy. For explanatory variables, molecular descriptors by computational chemistry and Morgan fingerprints were used for achieving high accuracy and simple prediction. The singlet-oxygen-scavenging mechanism was explained by the feature importance obtained from machine learning outputs. The results are consistent with conventional chemical knowledge. The use of machine learning and reduction in the number of measurements for screening high-antioxidant-capacity compounds can considerably improve prediction accuracy and efficiency.</jats:p>

その他リンク： https://www.mdpi.com/2076-3921/10/11/1751/htm

Kazuya Hayashi, Masumitsu Toyohara, Yohsuke Kusano, Shinichi Minohara, Yoshikaki Shimono, Hiroaki G … 全著者表示

Radiation Physics and Chemistry 179 109191-1 - 109191-6 2021年2月 [査読有り]

Prediction of the presence of cupping artifacts for gel dosimeter based on considerations of scattered light in optical computed tomography measurements

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Elsevier 共著

Kazuya Hayashi, Hiroaki Gotoh

Radiation Measurements 138 106437 - 106437 2020年11月 [査読有り]

DOI Web of Science CiNii Research

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Elsevier 共著

Abstract Measurements using three-dimensional (3D) gel dosimeters and optical computed tomography (CT) have exhibited tremendous potential for fast and accurate 3D dose verifications in radiation therapy. However, accurate measurements may not be possible owing to cupping artifacts. It has been reported that the Fricke and the polymer gel dosimeters induce considerable and extensive cupping artifact effects, whereas the micellar gel dosimeter exhibits a smaller effect. In this study, we estimated that the effect of cupping artifacts in the micellar dye gel dosimeter can be predicted by considering the absorption in the dye and the scattering induced by the gelling agent. Solutions with various absorbances were prepared and measured by optical CT. In parallel, changes in absorbance owing to the gelling agent were investigated using cells with different optical path lengths. Spectroscopic analyses demonstrated that the Lambert–Beer law holds for the light attenuation induced by the dyes and the gelling agent when measured with optical CT. We conclude that the generation of the cupping artifacts was attributed to the fact that the detection limit of the detector was exceeded owing to excessive light attenuation. In conclusion, we demonstrated the effectiveness of optical CT measurements based on the conversion of the measured value of the optical CT to absorbance and the prediction of the presence of cupping artifacts.

Structural and electronic factors relating to the stability of imidazolidine nitroxide radicals

Jun Naganuma, Shinya Nitta, Yudai Yamazaki, Hiroaki Gotoh

Journal of Computational Chemistry & Molecular Modeling 1 ( 4 ) 321 - 327 2020年2月 [査読有り]

記述言語：英語掲載種別：研究論文（学術雑誌）共著

A theoretical, dynamical evaluation method of the steric hindrance in nitroxide radicals using transition states of model reactions

Yamazaki Yudai, Naganuma Jun, Gotoh Hiroaki

SCIENTIFIC REPORTS 9 2019年12月 [査読有り]

記述言語：英語掲載種別：研究論文（学術雑誌）共著

Cause of cupping artifacts from radiochromic micelle gel dosimeters used in optical CT scanner measurement

Takaoki Takanashi, Kazuya Hayashi, Mikio Nemoto, Hiraku Kawamura, Shin-Ichiro Hayashi, Hiroaki Gotoh

Journal of Physics: Conference Series 1305 ( 1 ) 2019年8月 [査読有り]

記述言語：英語掲載種別：研究論文（学術雑誌）共著

Clear micelle gel dosimeter with nanoclay

K Hayashi, M Nemoto, T Takanashi, Y Kang, H Togo, J Kotoku, T Kobayashi, M Mihashi, S Hayashi , H G … 全著者表示

Journal of Physics: Conference Series 1305 ( 1 ) 2019年8月 [査読有り]

記述言語：英語掲載種別：研究論文（学術雑誌）共著

Evaluation of Nitroxide Radical Catalyst Activity in C-H Activation Step of the Oxidative Coupling between 9,10-Dihydroacridine and Nitromethane

KOUSUKE IWASAKI,YAMAZAKI YUDAI,HIROAKI GOTOH

ASSIIAN JJOURNAL OF CHEMIISSTRY 31 ( 9 ) 2107 - 2110 2019年7月 [査読有り]

記述言語：英語掲載種別：研究論文（学術雑誌）共著

Development of the radical C–O coupling reaction of phenols toward the synthesis of natural products comprising a diaryl ether skeleton

Kumpei Tanaka,Hiroaki Gotoh

Tetrahedron 2019年6月 [査読有り]

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：ELSEVIER 共著

Polymerization inhibition mechanism of 1,4-naphthoquinone by experimentation and DFT calculations

Takuji Takahashi,Yujirou Ikejiri,Shunichi Himori,Hiroaki Gotoh

Polymer Journal 2019年5月 [査読有り]

記述言語：英語掲載種別：研究論文（学術雑誌）共著

Evaluation method of steric shielding effect around nitroxide radical reaction center based on molecular volume within a virtual ball

Jun Naganuma,Yudai Yamazaki,Hiroaki Gotoh

Structural Chemistry 2085 - 2092 2019年4月 [査読有り]

記述言語：英語掲載種別：研究論文（学術雑誌）共著

Effect of Side Chain Functional Groups on the DPPH Radical Scavenging Activity of Bisabolane-Type Phenols

Kazuya Ichikawa, Ryosuke Sasada, Kosuke Chiba and Hiroaki Gotoh

Antioxidants 8 ( 3 ) 65 2019年3月 [査読有り]

有機分子触媒を用いた不斉反応:—プロリン誘導体を中心に—

記述言語：英語掲載種別：研究論文（学術雑誌）共著

五東弘昭

化学と教育 66 ( 10 ) 500 - 503 2018年

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：公益社団法人日本化学会単著

<p>近年，金属を用いずに有機化合物のみを用いた不斉触媒反応が活発に研究されている。本稿では，アミノ酸であるプロリンおよびその誘導体を用いた不斉触媒反応について解説する。なぜ，有機分子が触媒として作用し，立体選択的に生成物が得られるのかを紹介し，応用として有機分子触媒を鍵反応とした医薬品合成についても言及する。これら触媒は水や酸素に安定であり，操作上の利点を有しており，さらに生成物へ金属が混入する恐れがなく，グリーンケミストリーの観点からも注目されている。</p>

その他リンク： https://ci.nii.ac.jp/naid/130007722094

色素ゲル線量計および光学CTの評価

米原宗寛, 若菜亮, 榊原和久, 古徳純一, 小林毅範, 五東弘昭

医学物理 37 ( 2 ) 117 - 121 2017年11月 [査読有り]

記述言語：日本語掲載種別：研究論文（学術雑誌）共著

PVA-KI系ゲルインジケータの開発

T. Sunagawa, G. Harvel, Y. Aoki, M. Umeda, J. Hayami, K. Sakakibara, H. Goto, T. Evina, M. Taguchi, … 全著者表示

福井工業大学研究紀要 ( 47 ) 105 - 110 2016年3月 [査読有り]

記述言語：日本語掲載種別：研究論文（大学，研究機関紀要）共著

Trapping chlorine radicals via substituting nitro radicals in the gas phase

A. Seto, Y. Ochi, H. Gotoh, K. Sakakibara, S. Hatazawa, K. Seki, N. Saito, Y. Mishima

Analytical methods 8 25 - 28 2016年1月 [査読有り]

記述言語：英語掲載種別：研究論文（学術雑誌）共著

DPPHが、置換反応によって塩素ラジカルを捕獲することを発見した。また、この新規な捕獲方法の理論的考察を行った。

Novel Degradation Mechanism for Triarylmethane Dyes: Acceleration of Degradation Speed by the Attack of Active Oxygen to Halogen Groups

S. Nakagawa, K. Sakakibara, H. Gotoh

Dyes and Pigments 124 130 - 132 2016年1月 [査読有り]

記述言語：英語掲載種別：研究論文（学術雑誌）共著

トリアリールメタン系色素の紫外線による退色を、LC/MSやUV/VISにより解析したところ、Brを有するBasic Blue 1が特異的に退色することを見出した。また、その理由について考察した。

Two Reaction Mechanisms via Iminium Ion Intermediates: The Different Reactivities of Diphenylprolinol Silyl Ether and Trifluoromethyl‐Substituted Diarylprolinol Silyl Ether

H. Gotoh, Tadafumi Uchimaru, Yujiro Hayashi

Chemistry-A European Journal 21 ( 35 ) 12337 - 12346 2015年6月 [査読有り]

記述言語：英語掲載種別：研究論文（学術雑誌）共著

プロリン由来の有機分子触媒の一部を変える事によって、Michael 反応及びDiels Alder反応が選択的に進行することの理由の解明を行った。

A Theoretical and Experimental Study of the Effects of Silyl Substituents in Enantioselective Reactions Catalyzed by Diphenylprolinol Silyl Ether

Yujiro Hayashi, Daichi Okamura, Tatsuya Yamazaki, Yasuto Ameda, Hiroaki Gotoh, Seiji Tsuzuki, Tadaf … 全著者表示

Chemistry-A European Journal 20 ( 51 ) 17077 - 17088 2014年12月 [査読有り]

記述言語：英語掲載種別：研究論文（学術雑誌）共著

ジフェニルプロリノールシリルエーテルを用いた不斉触媒反応におけるシリル基の影響について詳細に調べ、その理由について考察した。

Scavenging and Characterization of Short-Lived Radicals Using a Novel Stable Nitroxide Radical with a Characteristic UV vis Absorption Spectrum

R Toba, H Gotoh, K Sakakibara

Organic letters 16 ( 15 ) 3868 - 3871 2014年7月 [査読有り]

記述言語：英語掲載種別：研究論文（学術雑誌）共著

アントラセンを有する新規ニトロキシドラジカルを開発し、開発した化合物がラジカルスカベンジング剤として有能であることを示した。

Proton-conductivity Enhancing Ionic liquid Consisting of Guanidine and Excess

M. Kuroha, H. Gotoh, M. S. Miran, T. Yasuda, M. Watanabe, K. Sakakibara

Chemistry Letters 43 ( 5 ) 649 - 651 2014年1月 [査読有り]

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：日本化学会共著

テトラメチルグアニジンと過剰量のトリフルオロメタンスルホン酸からイオン液体を合成し,その物性を伝導度, NMR, IR, Mass,　B3LYP/6-31G*による計算化学を用いて考察した。
過剰量のトリフルオロメタンをグアニジンに加えたイオン液体の正常評価に関する研究を行った。

New Insights into the Mechanism and an Expanded Scope of the Fe(III)-Mediated Vinblastine Coupling Reaction

Hiroaki Gotoh, Justin E. Sears, Albert Eschenmoser, Dale L. Boger

Journal of the american chemical society 134 ( 32 ) 13240 - 13243 2012年8月 [査読有り]

記述言語：英語掲載種別：研究論文（学術雑誌）共著

An Organocatalytic, Enantioselective Intramolecular [6+2] Cycloaddition Reaction for the Formation of Tricyclopentanoids and Insight on its Mechanism from a Computational Study

Y. Hayashi, H. Gotoh, M. Honma, K. Sankar, I. Kumar, H. Ishikawa, K. Konno, H. Yui, S. Tsuzuki, T. … 全著者表示

The Journal of American Chemical Society 133 ( 50 ) 20175 - 20185 2011年11月 [査読有り]

記述言語：英語掲載種別：研究論文（学術雑誌）共著

10'-Fluorovinblastine and 10'-Fluorovincristine: Synthesis of a Key Series of Modified Vinca Alkaloids

H. Gotoh, W. M. Rovertson, K. K. Duncan, D. L. Boger

ACS Medicinal Chemistry letters 2 ( 12 ) 948 - 952 2011年10月 [査読有り]

記述言語：英語掲載種別：研究論文（学術雑誌）共著

Catharanthine C16 Substituent Effects on the Biomimetic Coupling with Vindoline: Preparation and Evaluation of a Key Series of Vinblastine Analogues

A. Tam, H. Gotoh, W. M. Rovertson, D. L. Boger

Bioorganic & Medicinal Chemistry Letters 20 ( 22 ) 6408 - 6410 2010年11月 [査読有り]

記述言語：英語掲載種別：研究論文（学術雑誌）共著

One-pot Synthesis of Chiral Bicyclo [3.3.0] Octatrienes using Diphenylprolinol Silyl Ether-Mediated Ene-type Reaction

H. Gotoh, H. Ogino, H. Ishikawa, Y. Hayashi

Tetrahedron 66 ( 26 ) 4894 - 4899 2010年3月 [査読有り]

記述言語：英語掲載種別：研究論文（学術雑誌）共著

Diphenylprolinol Silyl Ether Catalysis in an Asymmetric Formal Carbo [3 + 3] Cycloaddition Reaction via a Domino Michael/Knoevenagel Condensation

Y. Hayashi, M. Toyoshima, H. Gotoh, H. Ishikawa

Organic Letters 11 ( 1 ) 45 - 48 2009年12月 [査読有り]

記述言語：英語掲載種別：研究論文（学術雑誌）共著

Diphenylprolinol Silyl Ether as a Catalyst in an Asymmetric, Catalytic, and Direct Michael Reaction of Nitroethanol with α,β-Unsaturated Aldehydes

H. Gotoh, D. Okamura, H. Ishikawa, Y. Hayashi

Organic Letters 11 ( 18 ) 4056 - 4059 2009年8月 [査読有り]

記述言語：英語掲載種別：研究論文（学術雑誌）共著

Diphenylprolinol Silyl Ether as a Catalyst in an Asymmetric, Catalytic and Direct α- Benzoyloxylation of Aldehydes

H. Gotoh, Y. Hayashi

Chemical Communications 3083 - 3085 2009年4月 [査読有り]

記述言語：英語掲載種別：研究論文（学術雑誌）共著

Asymmetric Diels-Alder Reactions of α,β-Unsaturated Aldehydes Catalyzed by a Diarylprolinol Silyl Ether Salt in the Presence of Water

Y. Hayashi, S. Samanta, H. Gotoh, H. Ishikawa

Angewandte Chemie International Edition 47 ( 35 ) 6634 - 6637 2008年8月 [査読有り]

記述言語：英語掲載種別：研究論文（学術雑誌）単著

Diphenylprolinol Silyl Ether as a Catalyst in an Enantioselective, Catalytic, Formal Aza [3+3] Cycloaddition Reaction for the Formation of Enantioenriched Piperidines

Y. Hayashi, H. Gotoh, R. Masui, H. Ishikawa

Angewandte Chemie International Edition 47 ( 21 ) 4012 - 4015 2008年4月 [査読有り]

記述言語：英語掲載種別：研究論文（学術雑誌）共著

Diphenylprolinol Silyl Ether as Catalyst of an Asymmetric, Catalytic, and Direct Michael Reaction of Nitroalkanes with α,β-Unsaturated Aldehydes

H. Gotoh, H. Ishikawa, Y. Hayashi

Organic Letters 9 ( 25 ) 5307 - 5309 2007年11月 [査読有り]

記述言語：英語掲載種別：研究論文（学術雑誌）共著

Organocatalyst -Mediated Enantioselective Intramolecular Aldol Reaction Featuring the Rare Combination of Aldehyde as Nucleophile and Ketone as Electrophile

Y. Hayashi, H. Sekizawa, J. Yamaguchi, H. Gotoh

The Journal of Organic Chemistry 72 ( 17 ) 6493 - 6499 2007年7月 [査読有り]

記述言語：英語掲載種別：研究論文（学術雑誌）共著

Diarylprolinol Silyl Ether as Catalyst of an exo-Selective, Enantioselective

H. Gotoh, Y. Hayashi

Organic Letters 9 ( 15 ) 2859 - 2862 2007年6月 [査読有り]