2003 Fiscal Year Final Research Report Summary
Efficient Methods for Asymmetric Synthesis Based on Asymmetric Transmission via Sigmatropic Rearrangements
| Project/Area Number |
14550821
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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 |
Synthetic chemistry
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| Research Institution | Niigata University |
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Principal Investigator |
NAKAI Takeshi NIIGATA UNIVERSITY, Graduate School of Science and Technology, Professor, 大学院・自然科学研究科, 教授 (90016717)
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| Co-Investigator(Kenkyū-buntansha) |
HASEGAWA Eietsu NIIGATA UNIVERSITY, Faculty of Science, Assoc.Professor, 理学部, 助教授 (60201711)
OKAMURA Mitsuo NIIGATA UNIVERSITY, Graduate School of Science and Technology, Assoc.Professor, 大学院・自然科学研究科, 助教授 (30215503)
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| Project Period (FY) |
2002 – 2003
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| Keywords | Sigmatropic Rearrangement / Carbanion Rearrangement / Wittig Rearrangement / Brook Rearrangement / Asymmetric Transmission / Borneol / Carvenol / Piperitol |
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| Research Abstract |
The main results of this 2-year project are as follows :
Theme (1)"The Mechanism of the Asymmetric Transmission via [2,3]-Wittig Rearrangement" : A series of experiments using chiral carbanion termini generated from optically active tin compounds provided pieces of evidence in support of the "dynamic kinetic resolution mechanism" for the asymmetric transmission concerned.
Theme (2)"Asymmetric Transmission via the [1,4]-Wittig Rearrangement" : First, the carbanion rearrangement of allyl endo-and exo-bornyl ether was found to predominantly undergo the rarely precedented [1,4]-Wittig rearrangement which proceeds in non-stereospecific manner. Second, similar (but at lower temperatures) rearrangements of allyl cis-carvenyl ether and allyl trans-piperityl ether were shown to undergo the [1,4]-Wittig rearrangement predominantly which proceeds with complete retention of configuration. Interestingly enough, the rearrangement of -allyl cis-piperityl ether was found to undergo the [2,3]-Wittig rearrangement exclusively. Thus, the substrate conformation has been revealed to play a key role in determining the periselectivity in these carbanion rearrangements. Third, three convenient procedures have been developed for effecting the [1,4]-retero-Brook rearrangement of allyl silyl ethers to afford the silylated (2)-enol silyl ethers.
Theme (3)"Asymmetric Transmission via Sequential Sigmatropic Rearrangements" : the sequential [2,3]-Wittig/oxy-Cope rearrangement of allyl cyclopentenyl ether was investigated. However, no work for evaluating the asymmetric transmission of the Sigmatropic sequence has been made yet.
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