1988 Fiscal Year Final Research Report Summary
Study for Highly Stereocontrolled Reactions by Liquid Crystalline Mesophases
| Project/Area Number |
62570944
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
補綴理工系歯学
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| Research Institution | Kumamoto University |
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Principal Investigator |
NAGAMATSU Tomohisa Faculty of Pharmaceutical Sciences, Kumamoto University, 薬学部, 助手 (40155966)
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| Project Period (FY) |
1987 – 1988
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| Keywords | Liquid crystal / Photodimerization / Nucleic acid base / Uracil / Asymmetric Diels-Alder reaction / Diastereomer / 高選択的反応 |
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| Research Abstract |
Photodimerizations and thermal cycloadditions in thermotropic liquid crystalline media were explored in order to show the utility of liquid crystals in organic reaction and chemical significance of the liquid crystalline phases was clarified.
1. A well documented photodimerization of uracils seemed to be a suitable reaction for the present study, and provided information regarding highly preferred orientations of solutes in liquid crystalline media. Thus methyluracils were irradiated with a high pressure HG-lamp in isotropic and anisotropic media including frozen solutions. The photodimer distribution and conversion yields were determined as a function of temperature and solvent phase. Smectic liquid crystalline medium significantly enhanced the stereoselectivity and the rate in photodimerization, in strong contrast to the isotropic phase reaction which gave poor dimer-selectivity and yield.
2. Alkyl and aryl cholesteryl fumarates were prepared to serve as a liquid crystalline dienophile in Diels-Alder reaction. Some of them showed cholesteric liquid crystial phases in temperature ranges suitable to the cycloaddition. The reaction of n-hexyl cholesteryl cholesteryl fumarate in mesomorphic phase as a dienophile with cyclopentadiene gave the optically active cycloadducts in 10% enantiomeric excess. On the other hand, the reaction of methyl cholesteryl fumarate with 2,6-dimethoxyanthracene gave 2,6-dimethoxy-9,10-dihydro-9,10-ethano-anthracene-11(syn),12(syn)-dicarboxylic acid and the 11(anti),12(anti)-isomer in a ratio of 96 : 4 (92% d.e.). These results clearly showed that a cholesteric mesophase could stereochemically control the diels-Alder reaction to a considerable extend.
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Research Products
(4 results)
