研究者詳細 - 塚本　眞幸

論文 - 塚本　眞幸

分割表示 >> ／全件表示 35 件中 1 - 35 件目

One-pot reduction of TEMPO derivatives by triethylsilane and trifluoroacetic acid: isolation and structural analysis of the air-stable TEMPOH ammonium trifluoroacetate 査読有り

K. Ando, K.-i. Oyama, S.-i. Kawano, H. Zhang, and M. Tsukamoto

Bull. Chem. Soc. Jpn. 98 巻 ( 11 ) 頁： 10.1093/bulcsj/uoaf107 2025年11月

Detection and behaviors of TEMPO derivatives in seven mass spectrometry ionization methods 査読有り Open Access

K.-i. Oyama, S. Hor, M. Tsukamoto, and H. Zhang

J. Mass Spectrom. 60 巻 ( 4 ) 頁： e5122 2025年3月

Synthesis and Characterization of Maleimide-Terminated Oligoimides Formed by a Michael Addition Reaction Using Methoxybenzenes 査読有り

T. Wakabayashi, S. Hor, K.-i. Oyama, and M. Tsukamoto

Tetrahedron 141 巻頁： 133486 2023年5月

Real-Time Monitoring of Enzyme-Catalyzed Phosphoribosylation of Anti-Influenza Prodrug Favipiravir by Time-Lapse NMR Spectroscopy. 査読有り

T. Sugiki, A. Ito, Y. Hatanaka, M. Tsukamoto, T. Murata, K. Miyanishi, A. Kagawa, T. Fujiwara, M. Kitagawa, Y. Morita, and M. Negoro

NMR Biomed. 36 巻 ( 5 ) 頁： e4888 2022年12月

Characterization of Organic Friction Modifiers Using Lateral Force Microscopy and Eyring Activation Energy Model. 査読有り

J. Hou, M. Tsukamoto, H. Zhang, K. Fukuzawa, S. Itoh, and N. Azuma

Tribol. Int. 178 巻 ( Part A ) 頁： 108052 2022年11月

Molecules with a TEMPO-Based Head Group as High-Performance Organic Friction Modifiers. 査読有り Open Access

J. Hou, M. Tsukamoto, S. Hor, X. Chen, J. Yang, H. Zhang, N. Koga, K. Yasuda, K. Fukuzawa, S. Itoh, and N. Azuma

Friction 11 巻 ( 2 ) 頁： 316 - 332 2022年5月

Synthesis and characterization of methoxybenzene-linked polyimides formed by 1,4-addition to bismaleimides 査読有り Open Access

Seanghai Hor, Kin-ichi Oyama, Nobuaki Koga, and Masaki Tsukamoto

Polymer 238 巻頁： 124326 2022年1月

Metal Ions Sensing by Biodots Prepared from DNA, RNA, and Nucleotides Open Access

Wang Maofei, Tsukamoto Masaki, Sergeyev Vladimir G., Zinchenko Anatoly

Biosensors 11 巻 ( 9 ) 2021年9月

記述言語：日本語出版者・発行元：Biosensors

Nucleic acids that exhibit a high affinity toward noble and transition metal ions have attracted growing attention in the fields of metal ion sensing, toxic metal ion removal, and the construction of functional metal nanostructures. In this study, fluorescent nanoparticles (biodots) were synthesized from DNA, RNA, and RNA nucleotides (AMP, GMP, UMP, and CMP) using a hydrothermal (HT) method, in order to study their metal ion sensing characteristics. The fluorescent properties of biodots differ markedly between those prepared from purine and pyrimidine nucle-obases. All biodots demonstrate a high sensitivity to the presence of mercury cations (Hg2+ ), while biodots prepared from DNA, RNA, and guanosine monophosphate (GMP) are also sensitive to Ag+ and Cu2+ ions, but to a lesser extent. The obtained results show that biodots inherit the metal ion recognition properties of nucleobases, while the nucleobase composition of biodot precursors affects metal ion sensitivity and selectivity. A linear response of biodot fluorescence to Hg2+ concentration in solution was observed for AMP and GMP biodots in the range 0–250 µM, which can be used for the analytic detection of mercury ion concentration. A facile paper strip test was also developed that allows visual detection of mercury ions in solutions.

DOI： 10.3390/bios11090333

Fluorescent Nanoparticles Synthesized from DNA, RNA, and Nucleotides 査読有り Open Access

Wang Maofei, Tsukamoto Masaki, Sergeyev Vladimir G., Zinchenko Anatoly

Nanomaterials 11 巻 ( 9 ) 2021年9月

記述言語：日本語出版者・発行元：Nanomaterials

Ubiquitous on Earth DNA and other nucleic acids are being increasingly considered as promising biomass resources. Due to their unique chemical structure, which is different from that of a more common carbohydrate biomass polymers, materials based on nucleic acids may exhibit new attractive characteristics. In this study, fluorescent nanoparticles (biodots) were prepared by a hydrothermal (HT) method from various nucleic acids (DNA, RNA, nucleotides, and nucleosides) to establish the relationship between the structure of precursors and fluorescent properties of biodots and to optimize conditions for preparation of the most fluorescent product. HT treatment of nucleic acids results in decomposition of sugar moieties and depurination/depyrimidation of nucleobases, while their consequent condensation and polymerization gives fluorescent nanoparticles. Fluorescent properties of DNA and RNA biodots are drastically different from biodots synthesized from individual nucleotides. In particular, biodots synthesized from purine-containing nucleotides or nucleosides show up to 50-fold higher fluorescence compared to analogous pyrimidine-derived biodots. The polymeric nature of a precursor disfavors formation of a bright fluorescent product. The reported effect of the structure of the nucleic acid precursor on the fluorescence properties of biodots should help designing and synthesizing brighter fluorescent nanomaterials with broader specification for bioimaging, sensing, and other applications.

DOI： 10.3390/nano11092265

Brønsted acid-catalyzed 1,4-addition of 1,3,5-trimethoxybenzene to maleimides and acrylates 査読有り Open Access

Seanghai Hor, Kin-ichi Oyama, Nobuaki Koga, and Masaki Tsukamoto

Tetrahedron Lett. 74 巻頁： Article 153100 2021年6月

Experimental Study of Application of Molecules with a Cyclic Head Group Containing a Free Radical as Organic Friction Modifiers 査読有り Open Access

X. Zhang, M. Tsukamoto, H. Zhang, Y. Mitsuya, S. Itoh, and K. Fukuzawa

J. Adv. Mech. Des. Syst. 14 巻 ( 4 ) 頁： JAMDSM0044 2020年4月

Recent Application of Acidic 1,3-Azolium Salts as Promoters in the Solution-Phase Synthesis of Nucleosides and Nucleotides 招待有り査読有り Open Access

M. Tsukamoto and K.-i. Oyama

Tetrahedron Lett. 頁： 2477-2484 2018年6月

A Solid-Supported Acidic Oxazolium Perchlorate as an Easy-Handling Catalyst for the Synthesis of Modified Pyrimidine Nucleosides via Vorbrüggen-type N-Glycosylation 査読有り Open Access

N. Basu, K.-i. Oyama, and M. Tsukamoto

Tetrahedron Lett. 58 巻 ( 20 ) 頁： 1921–1924 2017年5月

Synthesis of Ribonucleoside 3',5'-Cyclic Monophosphorodithioates 査読有り

A. Fukuhara and M. Tsukamoto

Tetrahedron 71 巻 ( 23 ) 頁： 3878-3884 2015年6月

Practical Synthesis of Adenosine 3',5'-Cyclic Monophosphorodithioate 査読有り

A. Fukuhara, H. Morita, K.-i. Oyama, and M. Tsukamoto

Tetrahedron Lett. 55 巻 ( 38 ) 頁： 5261-5263 2014年9月

Synthesis of Modified Pyrimidine Nucleosides via Vorbrüggen-type N-Glycosylation Catalyzed by 2-Methyl-5-phenylbenzoxazolium Perchlorate 査読有り

H. Shirouzu, H. Morita, and M. Tsukamoto

Tetrahedron 70 巻 ( 22 ) 頁： 3635-3639 2014年3月

Cyclic Bis(3'-5')diadenylic Acid (c-di-AMP) Analogs Promote the Activities of Photosynthesis and Respiration of Chlamydomonas reinhardtii 査読有り Open Access

T. Tezuka, H. Shirouzu, K. Ishida, N. Suzuki, T. Matsuo, K.-i. Oyama, S. Aoki, and M. Tsukamoto

Am. J. Plant Sciences 5 巻 ( 1 ) 頁： 24-28 2014年1月

Synthesis of 2'-Modified Cyclic Bis(3'-5')diadenylic Acids (c-di-AMPs) and Their Promotion of Cell Division in a Freshwater Green Alga 査読有り

T. Tezuka, N. Suzuki, K. Ishida, K.-i. Oyama, S. Aoki, and M. Tsukamoto

Chem. Lett. 41 巻 ( 12 ) 頁： 1723-1725 2012年12月

Controlling Glycosyl Bond Conformation of Guanine Nucleosides: Stabilization of the anti Conformer in 5'-O-Ethylguanosine 査読有り

H. Asami, S.-h. Urashima, M. Tsukamoto, A. Motoda, Y. Hayakawa, and H. Saigusa

J. Phys. Chem. Lett. 3 巻頁： 571–575 2012年2月

Practical Synthesis of Cyclic Bis(3'-5') diadenylic Acid (c-di-AMP) 査読有り

N. Suzuki, K.-i. Oyama, and M. Tsukamoto

Chem. Lett. 40 巻 ( 10 ) 頁： 1113-1114 2011年9月

Gas-Phase Isolation of Diethyl Guanosine 5'-Monophosphate and Its Conformational Assignment 査読有り

H. Asami, M. Tsukamoto, Y. Hayakawa, and H. Saigusa

Phys. Chem. Chem. Phys. 12 巻 ( 42 ) 頁： 13918-13921 2010年11月

Equilibrium of Homochiral Oligomerization of a Mixture of Enantiomers. Its Relevance to Nonlinear Effects in Asymmetric Catalysis 査読有り

M. Tsukamoto, K. Gopalaiah, and H. B. Kagan

J. Phy. Chem. B 112 巻 ( 48 ) 頁： 15361-15368 2008年12月

Enantiomeric products formed via different mechanisms: asymmetric hydrogenation of an α,β-unsaturated carboxylic acid involving a Ru(CH3COO)2[(R)-binap] catalyst 査読有り

M. Yoshimura, Y. Ishibashi, K. Miyata, Y. Bessho, M. Tsukamoto, and M. Kitamura

Tetrahedron 63 巻 ( 46 ) 頁： 11399-11409 2007年11月

Mechanism of Catalytic Asymmetric Hydrogenation of 2-Formyl-1-methylene-1,2,3,4-tetrahydroisoquinoline Using Ru(CH3COO)2[(S)-binap] 査読有り

M. Tsukamoto, M. Yoshimura, K. Tsuda, and M. Kitamura

Tetrahedron 62 巻 ( 23 ) 頁： 5448-5453 2006年6月

Origin of the Minor Enantiomeric Product in a Noyori Asymmetric Hydrogenation 査読有り

Y. Ishibashi, Y. Bessho, M. Yoshimura, M. Tsukamoto, and M. Kitamura

Angew. Chem. Int. Ed. 44 巻 ( 44 ) 頁： 7287-7290 2005年11月

記述言語：英語掲載種別：研究論文（学術雑誌）

The enantiomeric products of the catalytic hydrogenation of an isotopically labeled substrate were separated. The ratios of the isotopomers revealed that the major and minor enantiomers are formed mostly through different mechanisms. Hence, when analyzing the energy profile of an asymmetric catalytic reaction with the Arrhenius equation, two competing diastereomorphic catalytic cycles should be considered.

ジホスフィンロジウムおよびルテニウム錯体を用いるデヒドロアミノ酸類の触媒的不斉水素化の機構研究の新展開査読有り Open Access

塚本眞幸, 北村雅人

有機合成化学協会誌 63 巻 ( 9 ) 頁： 899-910 2005年9月

Novel Synthesis and Characterization of Bioconjugate Block Copolymers Having Oligonucleotides 査読有り

A. Noro, Y. Nagata, M. Tsukamoto, Y. Hayakawa, A. Takano, and Y. Matsushita

Biomacromolecules 6 巻 ( 4 ) 頁： 2328-2333 2005年

Carboxylic Acids as Promoters for Internucleotide-Bond Formation via Condensation of a Nucleoside Phosphoramidite and a Nucleoside: Relationship between the Acidity and the Activity of the Promoter 査読有り

Y. Hayakawa, T. Iwase, E. J. Nurminen, M. Tsukamoto, and M. Kataoka

Tetrahedron 61 巻 ( 8 ) 頁： 2203-2209 2005年

記述言語：英語掲載種別：研究論文（学術雑誌）

The relationship between the activity and the acidity of a carboxylic acid as a promoter for condensation of a nucleoside phosphoramidite and a nucleoside was investigated. The investigation revealed that the acid, the pKa value of which in acetonitrile is less than 18, is capable of promoting the condensation reaction, and acid with a pKa value outside of this range does not serve as a promoter. In carboxylic acids serving as promoters, the ones with higher acidity generally show greater activity. In particular, acids with a pKa value less than ca. 16 (measured by a potentiometric method), such as trichloroacetic acid (pKaZ10.6), trifluoroacetic acid (pKaZ12.7), dichloroacetic acid (pKaZ13.2 or 15.8), and 2,4-dinitrobenzoic acid (pKaZ16.1), show high levels of activity higher than that of conventionally used 1H-tetrazole. These carboxylic acids generally serve as excellent promoters for both the liquid-phase and the solid-phase synthesis of oligonucleotides via phosphoramidite method.

Is It Possible to Estimate the Enantioselectivity of a Chiral Catalyst from Its Racemic Mixture? 査読有り

F. Lagasse, M. Tsukamoto, C. J. Welch, and H. B. Kagan

J. Am. Chem. Soc. 125 巻 ( 25 ) 頁： 7490-7491 2003年

Recent Advances in the Measurement of Enantiomeric Excesses 査読有り

M. Tsukamoto and H. B. Kagan

Adv. Synth. Catal. 344 巻 ( 5 ) 頁： 453-463 2002年

Mechanism of Asymmetric Hydrogenation of α-(Acylamino)acrylic Esters Catalyzed by BINAP-Ruthenium(II) Diacetate 査読有り

M. Kitamura, M. Tsukamoto, Y. Bessho, M. Yoshimura, U. Kobs, M. Widhalm, and R. Noyori

J. Am. Chem. Soc. 124 巻 ( 23 ) 頁： 6649-6667 2002年

記述言語：英語掲載種別：研究論文（学術雑誌）

The mechanism of asymmetric hydrogenation of R-(acylamino)acrylic esters with Ru(CH3COO)2[(S)-binap] (BINAP ) 2,2′-bis(diphenylphosphino)-1,1′-binaphthyl), giving the S saturated products in more than 90 per cent enantiomeric excess, has been investigated by means of a kinetic study, deuterium labeling experiments, isotope effect measurements, and NMR and X-ray analysis of certain Ru complexes. The hydrogenation in methanol under a low H2 pressure proceeds via a monohydride-unsaturate mechanism that involves the initial RuH formation followed by a reaction with an olefinic substrate. The migratory insertion in the enamide-RuH chelate complex occurs reversibly and endergonically in an exo manner, giving a five-membered metallacycle intermediate. The cleavage of the Ru-C bond is achieved with either H2 (major) or CH3OH (minor). Both of the pathways result in overall cis hydrogenation products. The hydrogen at C(3) is mainly from an H2 molecule, and the C(2) hydrogen is from another H2 or protic CH3OH. The major S and minor R enantiomers are produced via the same mechanism involving diastereomeric intermediates. The turnover rate is limited by the step of hydrogenolysis of a half-hydrogenated metallacyclic intermediate. The participation of two different hydrogen donor molecules is in contrast to the pairwise dihydrogenation using a single H2 molecule in the Rh(I)-catalyzed reaction which occurs via a dihydride mechanism. In addition, the sense of asymmetric induction is opposite to that observed with (S)-BINAP-Rh(I) catalysts. The origin of this phenomenon is interpreted in terms of stereocomplementary models of the enamide/metal chelate complexes. A series of model stoichiometric reactions mimicking the catalytic steps has indicated that most NMR-observable Ru complexes are not directly involved in the catalytic hydrogenation but are reservoirs of real catalytic complexes or even side products that retard the reaction.

DOI： 10.1021/ja010982n

Synthesis of α-Amino Phosphonic Acids by Asymmetric Hydrogenation 査読有り

M. Kitamura, M. Yoshimura, M. Tsukamoto, and R. Noyori

Enantiomer 1 巻 ( 4-6 ) 頁： 281-303 1996年

Conformational Study on 2-Acyl-1-alkylidene-1,2,3,4-tetrahydroisoquinolines 査読有り

M. Kitamura, M. Tsukamoto, H. Takaya, and R. Noyori

Bull. Chem. Soc. Jpn. 69 巻 ( 6 ) 頁： 1695-1700 1996年

General Asymmetric Synthesis of Isoquinoline Alkaloids. Enantioselective Hydrogenation of Enamides Catalyzed by BINAP-Ruthenium(II) Complexes 査読有り

M. Kitamura, Yi Hsiao, M. Ohta, M. Tsukamoto, T. Ohta, H. Takaya, and R. Noyori

J. Org. Chem. 59 巻 ( 2 ) 頁： 297-310 1994年

Applicability of a Standardized Discrete Cosine Transform Coding Method to Character Images 査読有り

Y. Hoshino, D. Ando, S. Higashino, and M. Tsukamoto

J. Electronic Imaging 1 巻 ( 3 ) 頁： 322-327 1992年

　前のページ - 次のページ　

<塚本 眞幸>

論文 - 塚本 眞幸

<塚本　眞幸>

論文 - 塚本　眞幸