1998 Fiscal Year Final Research Report Summary
New Development of Asymmetric Olefination
| Project/Area Number |
09672141
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Chemical pharmacy
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| Research Institution | University of Shizuoka (1998)
Kyoto University (1997) |
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Principal Investigator |
TANAKA Kiyoshi University of Shizuoka, Pharm.Sci.Professor, 薬学部, 教授 (50093266)
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| Project Period (FY) |
1997 – 1998
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| Keywords | Asymmetric reaction / HWE reaction / Chiral phosphonate / Diketone / MO calculation / Axial chirality / Intramolecular reaction / Chiral allenes |
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| Research Abstract |
The scientific research works of the asymmeric olefination, the research planning of which are described in the grant application form in detail, were performed and the following results are obtained.
1. A variety of diketonic substrates were applied to the asymmetric olefination utilizing the axially chiral phosphonate reagent of the HWE type, and the general effectiveness of the reagent was positively proven. Therein, the absolute stereostructure of the products was determined by chemical transformations as well as the X-ray crystal analyses.
2. The mechanistic aspects of the reaction was considered, where the kinetically controlled mechanism of the nucleophilic attack of the anion to the ketonic substrate as the rate determining step was proposed. The direction of the nucleophilic attack was estimated by using model experiments of thc Grignard reagents. From these model experiments and the calculation, it turned out that the direction was governed by the orbital control factors rather
… More
than the steric ones.
3. A practical and efficient synthetic method based on the C-C bond formation was developed by using the BHT esters as the ketene equivalent. The new reaction system afforded the higher chemical and optical yield than the previously known method. In this study, it was shown that even the simple phenolic esters can be the precursor for the ketenes and gave the corresponding optically active allenic esters in satisfactory chemical and optical yield.
4. The o-symmetrical diketones bearing the optically active phosphonate moiety were designed and prepared and intramolecular asymmetric HWE reaction based on the discrimination of the carbonyls was investigated. The optically active ring system having quaternary carbon and tetra-substituted olefinic moiety was successfully constructed in satisfactory chemical and optical yield. The absolute stereostructure of some of the products was unambiguously elucidated by the X-ray crystal analysis.
5. The symmetrical metal (Fe and Cr) complexes of diene and arenes were applied as the substrates to the asymmetric olefination, and the corresponding olefinic products of the planar chirality was obtained in satisfactory chemical and optical yield.
6. The preliminary experiments of the kinetic resolution of the racemic ketones was investigated. In the case of some amino acid derivatives, the high optical yield of the olefinic products was achieved and these extensive investigations are in progress. Less
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