1998 Fiscal Year Final Research Report Summary
Exploration of Methods for the Design of Reactive Molecules and the Control of Stereoselectivity
| Project/Area Number |
08555214
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 展開研究 |
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| Research Field |
工業物理化学
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| Research Institution | KYOTO UNIVERSITY |
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Principal Investigator |
FUJIMOTO Hiroshi KYOTO UNIVERSITY,Graduate School of Engineering, Professor, 工学研究科, 教授 (40026068)
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| Co-Investigator(Kenkyū-buntansha) |
FUENO Hiroyuki KYOTO UNIVERSITY,Graduate School of Engineering, Assistant, 工学研究科, 助手 (30212179)
TACHIBANA Akitomo KYOTO UNIVERSITY,Graduate School of Engineering, Professor, 工学研究科, 教授 (40135463)
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| Project Period (FY) |
1996 – 1998
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| Keywords | ab initio MO calculations / interaction orbitals / projected reactive orbitals / allyl borons / pi-allyl platinum complex / pi-allyl palladium complex / Lewis acidic hardness |
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| Research Abstract |
The physical properties and chemical activities of molecules and reaction intermediates are not determined by the stable structure of molecules, but by the local structures, such as the specific atoms and functional groups, in those species. In this study, we have investigated allyl boron compounds and have estimated, for the first time, theoretically the electron-accepting ability and Lewis acidic hardness of the boron center. These quantities have been shown to change markedly depending on the type of auxiliary. The theoretically estimated reactivity of allyl boron compounds toward aldehydes has been demonstrated to give an excellent agreement with the activation energies calculated accurately by the ab initio MO method and to agree well also with the experimental results. We have revealed in this study the factors that should control the reactivity of allyl boron compounds and have provided a new reactivity scale which can be utilized for the design of novel boron reagents.
We have s
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tudied next the nucleophilic substitutions of the allyl carbons in palladium and platinum complexes of 2-chloro-2-propenyl ethyl carbonate, utilizing molecular orbital calculations and the concept of orbital interactions. In the case of platinum complexes, the calculations have shown that the metallacyclobutane structure and the eta^22-coordinated structure are comparable in energy and exchange of ligands in the eta^22-coordinated structure is not facile. Accordingly, the nucleophilic substitution should occur at the allyl carbon to give an allylated compound. In contrast, the metallacyclobutane structure is less stable than the eta^22-coordinated structure in the palladium complex. Substitution reaction takes place in the eta^22-complex to give an alkene compound as the major product. The reaction takes place catalytically in this case. The relative stability of the metallacyclobutane structure and the eta^22-structure has been interpreted very clearly in terms of the phase and overlap of the interaction orbitals. Less
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