Hayato Ichikawa
Osaka University of Pharmaceutical Sciences
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Publication
Featured researches published by Hayato Ichikawa.
Organic Letters | 2009
Yoshihide Usami; Marie Ohsugi; Koji Mizuki; Hayato Ichikawa; Masao Arimoto
An efficient synthesis of antitumor marine natural product (+)-pericosine A was achieved from (-)-quinic acid in 11.7% overall yield, which is 20 times better than our previously reported synthesis. The crucial steps of this synthesis include the regio- and stereoselective bromohydrination of an unstable diene and the ring opening of an epoxide. This synthetic route was applicable to a synthesis of (+)-pericosine C and also to a synthesis of (-)-pericosine C.
Bioorganic & Medicinal Chemistry Letters | 2008
Shinichiro Kamino; Hayato Ichikawa; Shun ichi Wada; Yuka Horio; Yoshihide Usami; Takako Yamaguchi; Toshiki Koda; Aki Harada; Kazusa Shimanuki; Masao Arimoto; Mitsunobu Doi; Yoshikazu Fujita
We have demonstrated the synthesis of regioisomerically pure unsymmetrical xanthene derivatives consisting of three units which can be independently modified to control their physical properties. The photochemical properties of the synthetic unsymmetrical xanthene derivatives were investigated in solution by UV-vis absorption and fluorescence measurements, and their cell imaging properties were examined by confocal laser-scanning microscopy.
Heterocycles | 2010
Hayato Ichikawa; Haruhiko Ohfune; Yoshihide Usami
The microwave-assisted double Sonogashira coupling of 3,4-diiodo-1-trityl and 1-phenylpyrazole with terminal acetylene took only three minutes. Dialkynylpyrazoles, the coupling products, were heated at 240 °C in the presence of 1,4-cyclohexadiene to obtain 2H-2-trityl and 2-phenylindazoles, respectively. This synthetic route to 2H-indazole, which was achieved via cyclization to form the 6-membered ring of dialkynylpyrazole, is a novel procedure.
Tetrahedron Letters | 1999
Takashi Ooi; Junko Morikawa; Hayato Ichikawa; Keiji Maruoka
Abstract Regio- and stereoselective ring-opening reaction of hetero-substituted epoxides with alkynyllithiums can be catalyzed by Me3Ga with remarkable efficiency at 0∼20 °C via pentacoordinate chelate-type complex.
Heterocycles | 2010
Hayato Ichikawa; Miho Nishioka; Masao Arimoto; Yoshihide Usami
A general procedure for the synthesis of 4-aryl-1H-pyrazoles by the Suzuki-Miyaura cross coupling reaction between 4-bromo-1H-1-tritylpyrazole and commercially available arylboronic acids was developed. Using this procedure, a direct synthesis of 4-aryl-1H-pyrazoles possessing functional groups, such as hydroxyl, nitro, and amino groups, on the aryl ring was realized. Those molecules could not be prepared by our previous synthesis of 4-aryl-1H-pyrazoles via the Kumada cross coupling reaction.
Journal of Sulfur Chemistry | 2012
Takeshi Kimura; Hayato Ichikawa; Toshiyuki Fujio; Yasushi Kawai; Satoshi Ogawa
4,7-Diethylbenzo[1,2,3]trithioles (1a–1c), 4,8-diethylbenzo[1,2-d:4,5-d′]bis[1,2,3]trithiole (1d), and 6, 10-diethyl[1,2,3]trithiolo[h]benzopentathiepin (1d′) were treated with sodium borohydride and 0.5 equiv. of p-xylylene dibromide to produce bridged molecules 2a–2d with two thiol groups. On oxidation of 2a with iodine in the presence of triethylamine, 28-membered macrocycle 3a, linked with two disulfide bonds, was obtained via a dimeric cyclization reaction, instead of a monomeric 14-membered macrocycle. Compounds 2b–2d were similarly treated with iodine and triethylamine to give 28-membered macrocycles 3b–3d. In the case of the reaction of 2c, a trimeric reaction occurred to produce 42-membered macrocycle 4 together with 3c. The structures of the cyclic molecules were determined by NMR and mass spectrometry, which was further supported by X-ray crystallographic analysis.
Heterocycles | 2009
Yoshihide Usami; Masao Arimoto; Kiyomi Kobayashi; Mikiko Honjou; Masako Yamanaka; Misaki Miyao; Hayato Ichikawa; Kenneth F. Bastow; Kuo-Hsiung Lee
Synthesis of (1S,3R)-2-aza-4-deoxypodophyllotoxin has been accomplished in 6 steps using Schollkopfs bislactim-ether methodology in 12% total yield. Bislactim-ether, which was originally prepared from commercially available L -valine and glycine, was used as the starting material. Our synthetic route was allied to easy access to aryltetralin type 2-azalignan analogues. Synthesized 2-azalignans were tested for in vitro anticancer activity using a panel of human cancer cell lines. Both of two (1S)-diastereomers (9a and 9b) of 2-aza-4-deoxypodophyllotoxin showed significant activity against human cancer cell lines: A-549 (lung), HTC-8 (ileocecal), and MCF-7 (breast cancer).
Chemical Communications | 2010
Shinichiro Kamino; Yuka Horio; Seiji Komeda; Katsuhiko Minoura; Hayato Ichikawa; Jun Horigome; Asana Tatsumi; Shinya Kaji; Takako Yamaguchi; Yoshihide Usami; Shun Hirota; Shuichi Enomoto; Yoshikazu Fujita
Tetrahedron | 2001
Takashi Ooi; Tomoya Miura; Keisuke Takaya; Hayato Ichikawa; Keiji Maruoka
Angewandte Chemie | 2001
Takashi Ooi; Hayato Ichikawa; Keiji Maruoka