| Project/Area Number |
04044203
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| Research Category |
Grant-in-Aid for Overseas Scientific Survey.
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| Allocation Type | Single-year Grants |
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| Research Institution | Tohoku University |
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Principal Investigator |
YAMAMOTO Yoshinori Tohoku Univ., Faculty of Science, Professor, 理学部, 教授 (60029519)
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| Co-Investigator(Kenkyū-buntansha) |
KEITH Smith スワンジー大学, 化学科, 教授
IBUKA Toshiro Kyoto Univ., Pharm.Sciences, Associate Professor, 薬学部, 助教授 (80025692)
ASAO Naoki Tohoku Univ., Faculty of Science, Assistant, 理学部, 助手 (60241519)
NEMOTO Hisao Tohoku Univ., Faculty of Science, Instructor, 理学部, 講師 (30208293)
SMITH Keith Department of Chemistry, Swansea Univ.Professor
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| Project Period (FY) |
1992
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| Project Status |
Completed (Fiscal Year 1992)
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| Keywords | Allylstannane / Lewis acid / Stereochemistry / Pentavalent stannate / Protic acid / Hemibrevetoxin / Asymmetric synthesis / Synthesis of cyclic ether |
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| Research Abstract |
The BF_3.OEt_2 mediated intramolecular cyclization of the gamma-oxo-substituted allylic tin having an aldehyde group at the terminus of the carbon chain proceeds in a stereocontrolled manner to give the seven membered beta-hydroxy cyclic ether with high diastereoselectivity. This method was applied for the synthesis of a 6-7-7-6 ring system as a model of brevetoxin B. On the way of this investigation we discovered that Bronsted acid catalyzed of Bu_4NF-TiCl_4 mediated cyclization of (Z)-owega-stannyl aldehyde gives syn cyclic ether, whereas (E)-isomer affords anti cyclic ether. To explain this stereochemical outcome, a push-pull mechanism was proposed. By using the allylic tin method, total synthesis of hemibrevetoxin B was attempted, and now have completed the stereocontrolled synthesis of the essential ring framework,6-6-7-7 system.
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