2007 Fiscal Year Final Research Report Summary
Simplification of the induced circular dichroism method and its application to biologically active natural products
| Project/Area Number |
18590025
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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 | Kyushu University of Health and Welfare |
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Principal Investigator |
HOSOI Shinzo Kyushu University of Health and Welfare, School of Pharmaceutical Sciences, Associate Professor (60209236)
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| Co-Investigator(Kenkyū-buntansha) |
SAKUSHIMA Akiyo Kyusyu University of Health Welfare, School of Pharmaceutical Sciences, Professor (40094833)
KIUCHI Fumiyuki National Institute of Biomedical Innovation, Research Center for Medicinal Plant Resources, Director (60161402)
TAKAHASHI Ichiro Fukui University, Faculty of Engineering, Associate Professor (90197129)
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| Project Period (FY) |
2006 – 2007
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| Keywords | circular dichroism / asymmetry / absolute configuration / molecular mechanics calculation / conformational analysis / amine / alcohol / natural products |
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| Research Abstract |
1) Circular dichroism in a chiral amide possessing an achiral bhaohthyl chromophore
The bisignate CD curves were observed at around 240 nm in all binaphthyl amides examined. In a conformational analysis of the derivatives, a close correlation was observed between the signs of exciton chirality and the screw senses of the two 2-naphthoyl groups (positive/clockwise; negative/counterclockwise). A semi-empirical molecular orbital calculation (AM1) suggested an intramolecular hydrogen bonding. The CD spectra of the antipodal amides changed into split curves centered at 225 nm after N-methylation. Furthermore, the calculated screw senses between the electric transition moments of the binaphthyl system in N-methyl amides were in good accordance with those expected from their exciton chiralities, indicating a possible application for determination of absolute configuration.
2) Induced circular dichroism and conformational analysis of 2.2'-binaphthyl esters derived from primary alcohols possessing a stereogenic center in the β-position
Induced bisignate CD curves were observed near 240 nm in all 2, 2'-binaphthyl esters derived from primary alcohols with a chiral center in the p-position of the hydroxyl group. Conformational analyses of the esters by molecular mechanics were performed. In some cases, the calculated screw sense between the two longitudinal transition moments of 2-naphthoate groups for the most stable conformer with clockwise or counterclockwise orientation was found to be different from that expected from their exciton chiralities. Therefore, CD calculations and conformational analyses of the two esters having strong or moderate interaction between the functional group of the substrate and the ester group of the 2-naphthoate were carried out by the time-dependent density functional theory (TD-DFT). The results suggested that the TD-DFT is strongly effective for determination of the absolute configuration of binaphthyl esters.
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