1991 Fiscal Year Final Research Report Summary
Design of the Molecules Bearing Specific Stereochemistry and Its Application to the Development of New Reactions
| Project/Area Number |
02453141
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
Chemical pharmacy
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| Research Institution | The University of Tokushima |
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Principal Investigator |
NAGAO Yoshimitsu The University of Tokushima, Faculty of Pharmaceutical Sciences, Professor, 薬学部, 教授 (40027074)
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| Co-Investigator(Kenkyū-buntansha) |
SANO Shigeki The University of Tokushima, Faculty of Pharmaceutical Sciences, Research Associ, 薬学部, 助手 (20226038)
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| Project Period (FY) |
1990 – 1991
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| Keywords | Conformational Analysis / Dynamic ^1H- and ^<13>C-NMR / X-ray Analysis / Axial Conformer / Cyclohexanone / Thiane / Bent Conformation / Sigmoid Conformation |
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| Research Abstract |
We are extensively developing a new system in which stereochemistry and reaction of the unique molecule can be regulated under the electronic control.
Conformational analysis of various six-membered ring compounds possessing alkoxy and silyloxy substituents has been performed by utilizing their dynamic <@D11@>D1H- and <@D113@>D1C-NMR, <@D1119@>D1Sn-NMR, and X-ray analyses. Thus, it was clarified that chair-type 3-silyloxy-substituted glutaric anhydride and glutarimide and the chair-type cyclohexanones possessing alkoxy or silyloxy group at the C4 position can predominantly adopt each corresponding substituent-axial conformer in their solution. Similar axial or pseudoaxial preference of silyloxy and benzyloxy groups at C4 of chair-type thiane-1-oxides, thiane-1, 1-dioxides, and dihydrothiines was recognized on their dynamic <@D11@>D1H-NMR spectra. Such axial preference of alkoxy and silyloxy groups of several six-membered compounds was also observed in their crystallographic structures. Existence of the electron-withdrawing moiety ((]SY.di-substituted left.[)C=O, (]SY.di-substituted left.[)SO, (]SY.di-substituted left.[)SO<@D22@>D2) and the low basicity of silyloxy- and alkoxy-oxygen atom proved to be essential for adopting the axial conformer, which could be rationalized in terms of a general hypothesis ; stabilization of the axial conformer due to C3, 5-Hsigma, C4-Osigma<@D1*@>D1 orbital overlap.
Several molecules, adopting a bent conformation stacked with both aromatics such as triazoles and benzene derivatives, have been developed and characterized by X-ray crystallographic and ^1H-NMR analyses. Bridging both aromatic moieties with a sulfonic ester bond seems to be an essential factor for the bent conformation. Design and synthesis of new molecules adopting a unique sigmoid conformation have been achieved on the basis of a molecular mechanic calculation.
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