Papers - YAMAMURA Hatsuo
-
Phosphodiester bond cleavage mediated by a cyclic beta-sheet peptide-based dinuclear zinc(II) complex Reviewed
K Yamada, Y Takahashi, H Yamamura, S Araki, K Saito, M Kawai
CHEMICAL COMMUNICATIONS ( 14 ) 1315 - 1316 2000
Language：English Publishing type：Research paper (scientific journal) Publisher：ROYAL SOC CHEMISTRY
A dinuclear Zn(II) complex of N-2 delta,N-2 delta,N-2'delta,N-2'delta-tetrakis(2-pyridylmethyl) derivative of cyclic peptide gramicidin S markedly accelerated the cleavage of the phosphodiester linkage of the RNA model substrate 2-hydroxypropyl p-nitrophenyl phosphate.
-
A facile preparation of indium enolates and their Reformatsky-and Darzens-type reactions Reviewed
Tsunehisa Hirashita, Kenji Kinoshita, Hatsuo Yamamura, Masao Kawai, Shuki Araki
Journal of the Chemical Society, Perkin Transactions 1 ( 5 ) 825 - 828 2000
Language：English Publishing type：Research paper (scientific journal)
Indium enolates were readily prepared by transmetalation of lithium enolates with indium trichloride, and were subsequently reacted with aldehydes to give β-hydroxy esters in high yields. Indium α-bromo enolates were also prepared and reacted with carbonyl compounds to give Darzens-type α,β-epoxy carbonyl products. © The Royal Society of Chemistry 2000.
DOI： 10.1039/a907334e
-
Shuki ARAKI, Kaori YAMAMOTO, Tomoko INOUE, Koji FUJIMOTO, Hatsuo YAMAMURA, Masao KAWAI, Yasuo BUTSUGAN, Jinkui ZHOU, Emerich EICHHORN,Anton RIEKER, Martina HUBER
J. Chem. Soc., Perkin Trans. 2 985 - 995 1999.04
Publishing type：Research paper (scientific journal)
-
Regioselective Allylation of Electron-deficient Alkenes with Organogallium and Organoindium Reagents Reviewed
Shuki ARAKI, Tomoaki HORIE, Motoshi KATO, Tsunehisa HIRASHITA, Hatsuo YAMAMURA, Masao KAWAI
Tetrahedron Lett. 40 2331 - 2334 1999.04
Publishing type：Research paper (scientific journal)
-
Preparation of gamma-Heterosubstituted Allylindium and Diindium Reagents and Their Reactions with Carbonyl Compounds Reviewed
Tsunehisa HIRASHITA, Toshiya KAMEI, Tomoaki HORIE, Hatsuo YAMAMURA, Masao KAWAI, Shuki ARAKI
J. Org. Chem. 64 172 - 177 1999.04
Publishing type：Research paper (scientific journal)
-
Preparation and Pproperties of Novel Gramicidin S Analogs Possessing a Tri-, Tetra- or Pentamethylene Bridge between Ornithine SideC.hains Reviewed
K. YAMADA, K. ANDO, Y. TAKAHASHI, Y. H. YAMAMURA, S. ARAKI, K. KOBAYASHI, R. KATAKAI, F. KATO, M. KAWAI
J. Peptide Res. 53 611 - 617 1999.04
Publishing type：Research paper (scientific journal)
-
Hatsuo YAMAMURA, Shinichi YAMADA, Keiko KOHNO, Nozomi OKUDA, Shuki ARAKI, Kyoko KOBAYASHI, Ryoichi KATAKAI, Kazuaki KANO, MasaoKAWAI
J. Chem. Soc., Perkin Trans. 1 2943 - 2948 1999.04
Publishing type：Research paper (scientific journal)
-
Hatsuo YAMAMURA, Daisuke Iida, Shuki ARAKI, Kyoko KOBAYASHI, Ryoichi KATAKAI, Kazuaki KANO, Masao KAWAI
J. Chem. Soc., Perkin Trans. 1 3111 - 3115 1999.04
Publishing type：Research paper (scientific journal)
-
Photochemistry of Mesoionic Compounds. Photochemical Conversion of 5-Azido-1,3-diaryltetrazolium Aalts to Novel TricyclicMesoions with a Tetrazolo[1,5-a]benzimidazole Skelton Reviewed
Shuki ARAKI, Hiromi HATTORI, Noriyuki SHIMIZU, Koji OGAWA, Hatsuo YAMAMURA, Masao KAWAI
J. Heterocyclic Chem. 36 863 - 867 1999.04
Publishing type：Research paper (scientific journal)
-
Optical Resolution and Absolute Configuration of N-Benzyloxycarbonyl-alpha-alkoxyglycines Reviewed
Masao KAWAI, Keiichi YAMADA, Kouji HOSODA, Yasuhiro OMORI, Shuji KATO, Nobuhiro NAGAYAMA, Seigo MASUI, Masao KAMIYA, HastuoYAMAMURA, Shuki ARAKI, Yasuo BUTSUGAN
Chirality 11 561 - 568 1999.04
Publishing type：Research paper (scientific journal)
-
Convenient Preparation of [OrnTTfa]2- and [Orn(Boc)2,Orn(Tfa)2'] gramicidin S, Versatile Unsymmetrically Protected Derivatives ofGramicidin S Reviewed
K. YAMADA, K. ANDO, Y. TAKAHASHI, H. YAMAMURA, S. ARAKI, M. KAWAI
J. Peptide Res. 54 168 - 173 1999.04
Publishing type：Research paper (scientific journal)
-
Chelation-controlled Regio- and Stereoselective Allylindation of Norbornenols Reviewed
Shuki ARAKI, Toshiya KAMEI, Yukimitsu IGARASHI, Tsunehisa HIRASHITA, Hatsuo YAMAMURA, Masao KAWAI
Tetrahedron Lett 40 7999 - 8002 1999.04
Publishing type：Research paper (scientific journal)
-
Convenient preparation of [Orn(Tfa)2]- and [Orn(Boc)2, Orn(Tfa)2']gramicidin S, versatile unsymmetrically protected derivatives of gramicidin S Reviewed
K. Yamada, K. Ando, Y. Takahashi, H. Yamamura, S. Araki, M. Kawai
Journal of Peptide Research 54 ( 2 ) 168 - 173 1999
Language：English Publishing type：Research paper (scientific journal)
Treatment of gramicidin S (GS) with trifluoroacetic anhydride afforded a derivative in which only one of the two Orn side chains was trifluoroacetylated in 72% yield, furnishing the first efficient method for the preparation of a monoprotected derivative of GS. The mono(Tfa) derivative [Orn(Tfa)2]GS was treated with di-tert-butyl dicarbonate to yield dually protected derivative [Orn(Boc)2, Orn(Tfa)2']GS from which another monoprotected derivative [Orn(Boc)2]GS was prepared in high yield. These unsymmetrically protected GS derivatives are versatile starting materials for the preparation of various other GS derivatives. As an example of application of the unsymmetrically protected derivatives, a dimeric GS derivative was prepared via a singly p-nitrobenzenesulfonyl(NBS)-activated derivative [Orn(Boc)2,Orn(NBS)2']GS.
-
Synthesis, electrochemical investigation and EPR spectroscopy of a reversible four-stage redox system based on mesoionic 5,5'-azinobis(1,3-diphenyltetrazole) and related mesoionic compounds Reviewed
Shuki Araki, Kaori Yamamoto, Tomoko Inoue, Koji Fujimoto, Hatsuo Yamamura, Masao Kawai, Yasuo Butsugan, Jinkui Zhou, Emerich Eichhorn, Anton Rieker, Martina Huber
Journal of the Chemical Society. Perkin Transactions 2 ( 5 ) 985 - 995 1999
Language：English Publishing type：Research paper (scientific journal) Publisher：Royal Society of Chemistry
Mesoionic 5,5'-azinobis(1,3-diphenyltetrazole) 1 was prepared, and its chemical oxidation gave stable crystals of the corresponding radical cation 1.+ and dication 12+, which reversibly gave back azine 1 on reduction with zinc. Electrochemical investigations of 1 using cyclovoltammetry and differential pulse voltammetry in pyridine (Py) or dichloromethane (DCM) also revealed the two reversible successive one-electron oxidations leading to dication 12+ via radical cation 1.+, both of which can be reduced to the neutral state 1. In the cathodic process, 1 was reduced by two consecutive one-electron transfers at only slightly different potentials up to the corresponding diamon 12- which could be re-oxidized to the neutral state
thus constituting a reversible four-stage redox system. Radical cation 1.+ and anion 1.- were characterized by EPR spectroscopy. In order to get more insights into the spin-density distribution of 1.+, the bis- and tetra-15N-labelled species 1a.+, 1b.+ and 1c.+ were synthesized and investigated by EPR and 15N as well as 14N ENDOR spectroscopy, revealing that the largest N hyperfine coupling constants are due to the nitrogen atoms of the central bridge. According to 1H ENDOR there seems to be a small coupling with the protons of both phenyl rings which cannot be resolved in the EPR spectrum. The electrochemical properties of the related mesoionic compounds 5-10 were also investigated in Py or DCM solutions. In the cathodic process, a reduction peak of 9 and 10 was observed due to their reversible one-electron reduction to the corresponding radical anions. The radical obtained on reduction of 10 was characterized by EPR spectroscopy. On the other hand, 5-8 can be reduced by a formal two-electron transfer up to the corresponding dianions which are re-oxidizable to the neutral state. In the anodic process, 9/10 undergo irreversible one-electron oxidations whereas 5/6 (in DCM) and 7/8 (in Py) experience reversible or irreversible step by step two-electron oxidations leading to the dications. In Py the oxidation products of 5/6 react to further species revealing two more oxidation and several rereduction peaks. On the other hand, the oxidation products of 7/8 are instable in DCM (one main oxidation and rereduction peak). The electrochemical data are discussed in terms of delocalization in the cations and conjugation in the dications.DOI： 10.1039/a809386e
-
Preparation and properties of novel gramicidin S analogs possessing a tri-, tetra- or pentamethylene bridge between ornithine side chains Reviewed
K. Yamada, K. Ando, Y. Takahashi, Y. Oda, H. Yamamura, S. Araki, K. Kobayashi, R. Katakai, F. Kato, Masao Kawai
Journal of Peptide Research 53 ( 6 ) 611 - 617 1999
Language：English Publishing type：Research paper (scientific journal)
Gramicidin S (GS) analogs in which the N(δ) atoms of the two Orn side chains are linked by an oligomethylene bridge [-(CH2)(n)-
n=3-5] were prepared via the bis(p-nitrobenzenesulfonyl) derivative [Orn(NBS)(2,2')]GS. For comparison the nonbridged secondary amino group-containing analog [Orn(ME)(2,2')]GS was also prepared. 1H NMR and CD spectral analysis indicated that these analogs adopt the same β-sheet conformation as GS. The antimicrobial activities of these analogs were very similar, but were slightly dependent on the bridge chain length, the trimethylene-bridge analog being the most potent. -
Preparation and properties of novel gramicidin S analogs possessing a polymethylene bridge between ornithine side chains Reviewed
K Yamada, K Ando, Y Takahashi, H Yamamura, S Araki, M Kawai
PEPTIDE SCIENCE - PRESENT AND FUTURE 775 - 776 1999
Language：English Publishing type：Research paper (international conference proceedings) Publisher：SPRINGER
-
Preparation and guest binding of novel β-cyclodextrin dimers linked with various sulfur-containing linker moieties t Reviewed
Hatsuo Yamamura, Shinichi Yamada, Keiko Kohno, Nozomi Okuda, Shuki Araki, Kyoko Kobayashi, Ryoichi Katakai, Kazuaki Kano, Masao Kawai
Journal of the Chemical Society - Perkin Transactions 1 ( 20 ) 2943 - 2948 1999
Language：English Publishing type：Research paper (scientific journal) Publisher：Royal Society of Chemistry
Novel cyclodextrin dimers (1, 2, 3 and 4) whose cyclodextrins were linked with sulfur-containing linkers, namely a thiodipropanamide, a dithiodipropanamide, a thiodiethanamide, or a dithiodiethanamide linker, were synthesized by a reaction of 6-amino-6-deoxycycIoheptaose 7 with the corresponding dicarboxylic acids. For their preparation, dicyclohexylcarbodiimide, l-(3-dimethylaminopropyl)-3-ethylcarbodiimideand(benzotriazol-l-yloxy) tripyrroIidinophosphonium hexafluorophosphate were examined as coupling reagents. 'H NMR studies of the dimers suggested an intramolecular inclusion of the linker moiety to the cyclodextrin cavity, which affected the complexation of guest molecules. Dimer 4 was converted to another type of dimer 5 by reductive cleavage of the disulfide bond to generate thiol group-containing mononieric species followed by a substitution reaction with 6-O-tosyl derivative 6. © The Royal Society of Chemistry 1999.
DOI： 10.1039/a905067a
-
Polysulfonylated cyclodextrins. Part II.1 Preparation and structural validation of three isomeric pentakis(6-0-mesitylsulfonyl)cyclomaltoheptaoses f Reviewed
Hatsuo Yamamura, Daisuke Lida, Shuki Araki, Kyoko Kobayashi, Ryoichi Katakai
Journal of the Chemical Society - Perkin Transactions 1 ( 21 ) 3111 - 3115 1999
Language：English Publishing type：Research paper (scientific journal) Publisher：Royal Society of Chemistry
Three isomers of cyclomaltoheptaose derivatives, la-c, which possess five mesitylenesulfonyloxy groups on their C-6 atoms, were prepared. Assignment of the regiosiomers was performed by their conversion into compounds containing five 3,6-anhydroglucose units followed by 'H NMR analyses. The structures of the pentakis(3,6-anhydro) derivatives were also confirmed by their derivation from the known bis(TBDMS) derivatives. ©The Royal Society of Chemistry 1999.
DOI： 10.1039/a906436b
-
Photochemistry of mesoionic compounds. Photochemical conversion of 5-azido-1,3-diaryltetrazolium salts to novel tricyclic mesoions with a tetrazolo[1,5-a]benzimidazole skeleton Reviewed
Shuki Araki, Hiromi Hattori, Noriyuki Shimizu, Koji Ogawa, Hatsuo Yamamura, Masao Kawai
Journal of Heterocyclic Chemistry 36 ( 4 ) 863 - 867 1999
Language：English Publishing type：Research paper (scientific journal) Publisher：HeteroCorporation
A new type of tetrazolium-5-amide mesoions 2 with a tricyclic tetrazolo[1,5-a]benzimidazole skeleton has been synthesized via photolysis of 5-azido-1,3-diaryltetrazolium salts 1.
-
Optical resolution and absolute configuration of N-benzyloxycarbonyl-alpha-alkoxyglycines Reviewed
M Kawai, K Yamada, K Hosoda, Y Omori, S Kato, N Nagayama, S Masui, M Kamiya, H Yamamura, S Araki, Y Butsugan
CHIRALITY 11 ( 7 ) 561 - 568 1999
Language：English Publishing type：Research paper (scientific journal) Publisher：WILEY-LISS
Optical resolution of racemic N-benzyloxycarbonyl-protected alpha-alkoxy-glycines, (+/-)-Cbz-Gly(OR)-OH (R = Et and Pr-2), was achieved by means of fractional crystallization of diastereomeric salts with (+)-(1S,2S)-2-amino-1-phenyl-1,3-propanediol or diastereomeric esters of (+)- or (-)-menthol. The D- and L-configurations were assigned to the (+)- and (-)-Cbz-Gly(OR)-OH, respectively, based on L-enantioselective enzymatic hydrolysis of (+/-)-Cbz-Gly(OR)-OR' (R = Me, Et, and Pr-i; R' = CH2CF3 and Me) using porcine pancreatic lipase and papain. Chiroptical properties and HPLC retention times of D- and L-Gly(OR)-residue (R = Me and Pr-i)-containing peptides were compared in relation to their configurational assignments. (C) 1999 Wiley-Liss, Inc.
