Toshihisa Ogawa
Taisho Pharmaceutical Co.
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Tetrahedron Letters | 1993
Toshihisa Ogawa; Keita Matsumoto; Misa Yoshimura; Katsuo Hatayama; Kunihiro Kitamura; Yasuyuki Kita
Abstract Hantzsch cyclization of cyanoethyl 3-aminocrotonate and (E,Z)-4-dialkoxymethyl-2-benzylidene-acetoacetates (5a,b) afforded 3,4-trans-2-hydr
Tetrahedron-asymmetry | 1993
Takashi Adachi; Mayumi Ishii; Yoko Ohta; Tomomi Ota; Toshihisa Ogawa; Kazunori Hanada
Abstract (4 R )-(−)-2-(Nicotinoylamino)ethyl 3-nitrooxypropyl 2,6-dimethyl-4-(3-nitrophenyl)-1,4-dihydro-3,5-pyridinedicarboxylate ( 1 ), a new calcium antagonist, was synthesized via both enantioselective hydrolysis and transesterification of prochiral bis[2-(nicotinoylamino)ethyl]ester · 2HCl ( 5 ) by using enzymes. Hydrolysis of 5 by proteases originated from Aspergillus melleus and Bacillus licheniformis etc. in aqueous media afforded (4 R )-(−)-3-[2-(nicotinoylamino)-ethoxycarbonyl]-2,6-dimethyl-4-(3-nitrophenyl)-1,4-dihydropyridine-5-carboxylic acid ( 6 ) in more than 99% e.e., which was converted to 1 by esterification with 3-nitrooxypropyl bromide. Enzymatic transesterification of 5 with 3-nitrooxypropanol gave 1 in more than 99.5% e.e. directly.
Journal of The Chemical Society-perkin Transactions 1 | 1993
Toshihisa Ogawa; Keita Matsumoto; Chihiro Yokoo; Katsuo Hatayama; Kunihiro Kitamura
Enantiomeric (+)- and (–)-methy3-nitrooxypropyl 1,4-dihydro-2,6-dimethyl-4-(3- nitrophenyl) pyridine-3,5-dicarboxylate 1 were synthesized by esterification of the optically active monocarboxylic acids (+)-6 and (–)-6, which are available from racemate (±)-6 by optical resolution using cinchonidine and cinchonine. The absolute configuration of the key intermediates (S)-(+)-6 and (R)-(–)-6, was also unambiguously determined by the comparison with optical active (+)- and (–)-1 derived from (R)-(–)- and (S)-(+)-7 and (+)- and (–)-6, and X-ray crystallographic analysis of bromoethyl ester (R)-(–)-8 prepared from the acid (S)-(+)-7.
Journal of The Chemical Society-perkin Transactions 1 | 1993
Toshihisa Ogawa; Keita Matsumoto; Katsuo Hatayama; Kunihiro Kitamura; Yasuyuki Kita
Hantzsch cyclization of cyanoethyl 3-aminocrotonate and (E,Z)-4,4-dialkoxy-2-benzylideneacetoacetates 12a–h afforded the corresponding 3,4-trans-2-hydroxy-1,2,3,4-tetrahydropyridines 14a–h with high stereoselectivity. 1H NMR and X-ray analyses of compound 14a established the configuration of 3-H and 4-H as trans and that of 3-H and 2-OH as trans also.
Chemical & Pharmaceutical Bulletin | 1993
Toshihisa Ogawa; Atsuro Nakazato; Katsuharu Tsuchida; Katsuo Hatayama
Archive | 1983
Katsuo Hatayama; Aturo Nakazato; Toshihisa Ogawa; Shoichi Ito; Jiro Sawada
Chemical & Pharmaceutical Bulletin | 1994
Toshihisa Ogawa; Katsuo Hatayama; Hiroshi Maeda; Yasuyuki Kita
Archive | 1985
Yoshimoto Nakashima; Toshihisa Ogawa; Atsuro Nakazato; Yukinari Kumazawa; Kaoru Sota
Chemical & Pharmaceutical Bulletin | 1994
Yasuyuki Kita; Hiroshi Maeda; Fumie Takahashi; Seiji Fukui; Toshihisa Ogawa; Katsuo Hatayama
Synthesis | 1990
Toshihisa Ogawa; Atsuro Nakazato; Masakazu Sato; Katsuo Hatayama