Michiharu Kato
Tohoku University
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Featured researches published by Michiharu Kato.
Synthetic Communications | 1998
Hisahiro Hagiwara; Kimie Morohashi; Toshio Suzuki; Masayoshi Ando; Isao Yamamoto; Michiharu Kato
Abstract Primary alcohols and phenols have been acetylated with acetylimidazole by the solid state reaction, grinding both substrates with a pestle in a mortar.
Tetrahedron | 1995
Fusao Kido; Kazuo Yamaji; Subhash C. Sinha; Toshiya Abiko; Michiharu Kato
Abstract The rhodium(II)-catalyzed cyclization of acyclic α-diazo-β-keto esters 1c,d provided stereoselectively the highly substituted cyclohexanones 3c,d respectively, by the [2,3]sigmatropic rearrangement via stereocontrolled nine-membered allylsulfonium ylides 2c,d. Further elaboration of 3d toward the cyclohexanone 36 accomplished asymmetric formal syntheses of the representative elemanoids, 37 and 38. The compound 3c was transformed into the cyclohexanone 34a and cyclohexene 43, which could serve as the key intermediates for the synthesis of natural products possessing contigously cis-arranged trimethylcyclohexanone and its related moieties, respectively.
Tetrahedron | 1997
Hisahiro Hagiwara; Satoru Ohtsubo; Michiharu Kato
Abstract Thiocarbonylimidazolide 3 has been prepared from alcohol 1 and thiocarbonyldiimidazole 2 by grinding both substrates with pestle and mortar.
Tetrahedron | 1971
Tetsuo Nozoe; Kahei Takase; Michiharu Kato; T. Nogi
Abstract Reaction of 2-arylsulfonyloxytropones (IV) and active methylene compounds, diethyl malonate, ethyl acetoacetate, ethyl cyanoacetate, malononitrile or cyanoacetamide, in the presence of NaOEt give 8-hydroxy-2H-cyclohepta[b]furan-2-one derivatives (V) and/or 2-amino-8H-cyclohepta[b]furan-8-one derivatives (VII), in addition to azulene derivatives (1) or 2H-cyclohepta(b]furan-2-one derivatives (II), known to be obtained by the reaction of 2-chlorotropones or 2-methoxytropones with active methylene compounds. Relative yields of products are influenced markedly by conditions, e.g. base type or molar ratios. The formation of V and VII is characteristic of 2-arylsulfonyloxytropones, not being observed with 2-chlorotropones or 2-methoxytropones. A reaction course involving elimination of the arylsulfonyl group as arenesulfinate ion is presented.
Molecular Crystals and Liquid Crystals | 1996
Hisahiro Hagiwara; Satoru Ohtsubo; Michiharu Kato
Abstract Thiocarbonylimidazolide has been prepared from thiocarbonyl-diimidazole and alcohol simply by grinding in a mortar at ambient temperature.
Tetrahedron | 1987
Michiharu Kato; Yukio Matsumura; Kiyoshi Heima; Narihiko Fukamiya; Chizuko Kabuto; Akira Yoshikoshi
Abstract The stereoselective synthesis of dl -siccanin (1) and dl -siccano-chromene E (2) has been described. Acid isomerization of nonconjugated octalone 11a, derived from known octalone 5, stereoselectively provided cis-fused octalone 12, from which cis -drimane aldehyde 31 was obtained. After condensation of 31 with lithio-orcinol dimethyl ether, the product 32 was treated with pyridinium chloride to give tetrahydrofuran 33 whose complete stereostructure was unambiguously established by an X-ray crystal analysis. While cyclization of monophenol 34, obtained by partial demethylation of 33, with sulfuric acid afforded siccanochromene E methyl ether (35), reaction of 34 with Lewis acid gave siccanin methyl ether (36) along with 35. In the latter cyclization, the formation of 36 was demonstrated to occur from initially formed 35. Finally, demethylation of 35 and 36 provided 2 and 1, respectively. A novel tetrahydrofuran formation by a neighboring participation, which was observed in hydroxy ketone 24 and diol 32, are also discussed.
Journal of The Chemical Society, Chemical Communications | 1990
Michiharu Kato; Masataka Watanabe; Bernhard Vogler; Youichi Tooyama; Akira Yoshikoshi
Starting with (R)-(–)-cryptone, prepared in 42% overall yield from (+)-nopinone in five steps, the first synthesis of noroxopenlanfuran was accomplished, confirming its absolute configuration.
Journal of The Chemical Society-perkin Transactions 1 | 1997
Nobuhiko Ito; Takeaki Etoh; Hisahiro Hagiwara; Michiharu Kato
Synthesis of 4-alkylidene-3,5,5-trimethylcyclohex-2-enones 7 has been achieved utilising 1,4-conjugate dehydrobromination of allylic bromides 5 as a key step. This chemical transformation is applied to the synthesis of degradation products of carotenoids: megastigmatrienones 7e/1–4, 4-methylene-3,5,5-trimethylcyclohex-2-enone 7a, 4-(3-hydroxybutylidene)-3,5,5-trimethylcyclohex-2-enone 9, 1,3,7,7-tetramethyl-2-oxabicyclo[4.4.0]dec-5-en-9-one 10a–b and 3,4,7,8-tetrahydro-4,4,7-trimethylnaphthalen-2(6H)-one 15. A novel photoisomerisation of 4-[(Z )-3-acetoxybut-2-enyl]-4-hydroxy-3,5,5-trimethylcyclohex-2-enone 19 to 4-[(E )-3-acetoxybut-2-enyl]-4-hydroxy-3,5,5-trimethylcyclohex-2-enone 20 enables us to synthesise blumenol-A 21.
Tetrahedron Letters | 1991
Fusao Kido; Yasuhiko Kawada; Michiharu Kato; Akira Yoshikoshi
endo-4-Ethoxycarbonyl-4-(phenylthio)-9-methylene-2-oxabicyclo-[3.3.1]nonan-3-ones (5a–c) and their related compounds 5e–h, endo-4-ethoxycarbonyl-4-(phenylthio)-8-methylene-2-oxabicyclo[3.2.1]octan-3-one (5d) were synthesized from α-diazomalonates 3 of 2-(phenylthio)cyclohex-2-en-1-ols (1a–c) and their related compounds e–h, and 2-(phenylthio)cyclopent-2-en-1-ol (1d), respectively, via the [2,3]sigmatropic rearrangement of cyclic allylsulfonium ylides 4.
Journal of The Chemical Society-perkin Transactions 1 | 1973
Narihiko Fukamiya; Michiharu Kato; Akira Yoshikoshi
The total synthesis of (±)-seychellene (4,7,8-trimethyl-11-methylenetricyclo[5.3.1.03,8]undecane)(I) from2,3-di-methylcyclohex-2-en-1-one (XIV) is described. The ketone (XIV) was converted into 2-methyl-2-(3-methyl-5-iodopentyl)-3-methylenecyclohexan-1-one (XV), which gave 2-methyl-2-(3-methyl-5-iodopentyl)-3-bromo-methylcyclohexa-3,5-dien-1-one (XIX) with N-bromosuccinimide. Treatment of bromo-ketone (XIX) with chromium(II) chloride followed by acid gave 2,3-dimethyl-2-(3-methyl-5-iodopentyl)cyclohexa-3,5-dien-1-one (XXI). 2,3-Dimethyl-2-(3-methyl-5-dimethylaminopentyl)cyclohexa-3,5-dien-1-one (XXII) was obtained from the dienone (XXI) and was oxidised; pyrolysis of the resulting N-oxide yielded 4,7,8-trimethyltricyclo-[5.3.1.03,8]undec-9-en-11-one (VII). The adduct (VII) was hydrogenated to (±)-norseychellanone (4,7,8-trimethyltricyclo[5.3.1.03,8]undecan-11 -one), whose transformation into (±)-seychellene is known.