Hirokazu Arimoto
Tohoku University
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Publication
Featured researches published by Hirokazu Arimoto.
Tetrahedron Letters | 1998
Hirokazu Arimoto; Ichiro Hayakawa; Makoto Kuramoto; Daisuke Uemura
Abstract The absolute stereochemistry of a marine alkaloid halichlorine, which significantly inhibits VCAM-1 induction in HUVE cells, was established by synthesis of a degradation product of natural product.
Tetrahedron Letters | 1999
Noboru Takada; Hiroko Sato; Kiyotake Suenaga; Hirokazu Arimoto; Kaoru Yamada; Katsuhiro Ueda; Daisuke Uemura
Abstract Novel macrolides, haterumalides NA ( 1 ), NB ( 2 ), NC ( 3 ), ND ( 4 ), and NE ( 5 ), were isolated from an Okinawan sponge Ircinia sp. The absolute stereostructure of 1 was determined by spectroscopic analysis and modified Moshers method. Haterumalide NA ( 1 ) showed cytotoxicity against P388 cells and acute toxicity against mice.
Tetrahedron Letters | 1999
Hirokazu Arimoto; Shigehiro Asano; Daisuke Uemura
An asymmetric synthesis of the spirocyclic core of pinnaic acid, a cPLA~ inhibitor, is described. A key transformation in the sequence involves an asymmetric Michael-initiated ring closure.
Journal of Medicinal Chemistry | 2010
Yuki Nakama; Osamu Yoshida; Masanori Yoda; Keisuke Araki; Yuri Sawada; Jun Nakamura; Shu Xu; Kenji Miura; Hideki Maki; Hirokazu Arimoto
Novel semisynthetic vancomycin derivatives with antibacterial activity against vancomycin-resistant S. aureus (VRSA) were prepared. Replacement of Cl groups of vancomycin by Suzuki-Miyaura cross-coupling reaction, which gave the title compounds, is described for the first time. Introduction of a carbon substituent at the amino acid residue 2 of vancomycin led to an enhancement of antibacterial activity against vancomycin-resistant strains, whereas the additional introduction at the amino acid residue 6 resulted in a reduction in activity even against vancomycin-susceptible strains.
Chemical Communications | 1999
Hirokazu Arimoto; Kazuya Nishimura; Ichiro Hayakawa; Tomoya Kinumi; Daisuke Uemura
A multivalent polymer of vancomycin, synthesized via ring-opening metathesis polymerization (ROMP), exhibited significant enhancement of antibacterial activity against vancomycin-resistant enterococi (VRE).
Chemical Communications | 2004
Tetsuya Sengoku; Hirokazu Arimoto; Daisuke Uemura
Synthesis of the C13-C19 C-glycoside portion of kendomycin was achieved via oxidative pyran cyclization and Claisen rearrangement to construct the fully functionalized aromatic ring.
Chemical Communications | 2008
Yohei Saito; Hirobumi Taguchi; Shigemoto Fujii; Tomohiro Sawa; Eriko Kida; Chizuko Kabuto; Takaaki Akaike; Hirokazu Arimoto
Azido- and fluoro- derivatives of 8-nitroguanosine were developed, and will contribute to the exploration of protein S-guanylation by endogenous nitrated nucleosides.
Chemical Communications | 2007
Jun Lu; Osamu Yoshida; Sayaka Hayashi; Hirokazu Arimoto
A novel and efficient avenue for the preparation of dimeric vancomycins is described, and the dimers exhibited excellent antibacterial activities in the murine infection model.
Pure and Applied Chemistry | 2009
Daisuke Uemura; Masaki Kita; Hirokazu Arimoto; Makoto Kitamura
The discovery of new ecologically active compounds often triggers the development of basic scientific concepts in the field of biological sciences, since such compounds have direct physiological and behavioral effects on other living organisms. We have focused on the identification of natural key compounds that control biologically and physiologically intriguing phenomena. We describe three recent aspects of chemical ecology that we have investigated: natural toxins, coral communities, and symbiotic relationships. Blarina toxin (BLTX) is a lethal mammalian venom that was isolated from the short-tailed shrew. Duck-billed platypus venom shows potent Ca2+ influx in neuroblastoma cells. The venom of the solitary wasp contains arginine kinase-like protein and is used to paralyze its prey to feed its larva. The ecological behaviors of corals are controlled by combinations of small molecules. The polyol compound symbiodinolide may serve as a defense substance for symbiotic dinoflagellates to prevent digestion of their host animals. These compounds reveal the wonder of nature, in both terrestrial and marine ecological systems.
Chemistry-an Asian Journal | 2014
Shu Xu; Daisuke Unabara; Daisuke Uemura; Hirokazu Arimoto
The enantioselective total synthesis of the bioactive marine natural products pinnaic acid and halichlorine is reported in detail. Our total synthesis features the construction of the five-membered ring and C9 and C13 stereogenic centers through a palladium-catalyzed trimethylenemethane [3+2] cyclization; the installation of the nitrogen atom through a regioselective Beckmann rearrangement of a poorly reactive ketone; the stereoselective cyclization of the spiro ring through a four-step, one-pot hydrogenation-cyclization; and efficient connection of the sterically hindered lower chain through a reduced-pressure cross olefin metathesis reaction.