Generation of Chiral Carbanions by Chirality Transfer
| Project/Area Number |
15390006
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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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 | HIROSHIMA UNIVERSITY |
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Principal Investigator |
TAKEDA Kei Hiroshima University, Graduate School of Biomedical Sciences, Professor, 大学院・医歯薬学総合研究科, 教授 (30135032)
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| Project Period (FY) |
2003 – 2005
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| Project Status |
Completed (Fiscal Year 2005)
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| Budget Amount *help |
¥15,100,000 (Direct Cost: ¥15,100,000)
Fiscal Year 2005: ¥4,200,000 (Direct Cost: ¥4,200,000)
Fiscal Year 2004: ¥4,200,000 (Direct Cost: ¥4,200,000)
Fiscal Year 2003: ¥6,700,000 (Direct Cost: ¥6,700,000)
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| Keywords | organic synthesis / asymmetric synthesis / chirality transfer / rearrangement reactions / tandem reactions / annulation reactions / 不斉カルバニオン / 転移反応 / エナンチオ選択的反応 / エポキシシラン / キラルエポキシド |
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| Research Abstract |
This project was conducted to establish the feasibility of chirality transfer from epoxide to a carbanion. The key feature of the transfer involves our previously-developed epoxysilane rearrangement in which γ-metalated α,β-epoxysilane undergoes anion-induced ring opening followed by Brook rearrangement to give β-siloxy allyl anion. To realize the chirality transfer, we have conducted the following experiments.
1.Development of eight-membered carbocycles and heterocycles by Brook rearrangement-mediated [3 + 4] annulation.
2.Mechanistic studies of the epoxysilane rearrangement.
3.Development of cascade-type ring-forming reactions using the epoxysilane rearrangement.
4.Studies on the formation and stability of five-coordinated silicate intermediates.
5.Trap of a chiral carbanion generated via the epoxysilane rearrangement by [2,3]-Wittig rearrangement.
From these experiments, we obtained the following results.
1.We demonstrated the possibility of chirality transfer from epoxide to remote positions in Brook rearrangement-mediated [3+4] annulation
2.α,β-Epoxysilanes bearing a γ-tolyl group can function as an acrolein β-anion equivalent.
3.Chiral carbanions generated by chiral transfer from epoxide can be trapped by [2,3]-Wittig rearrangement without racemization.
4.We have found that chiral nonracemic α-nitrile allylic carbanions can be generated by chirality transfer from epoxysilanes via Brook rearrangement, and they have configurational stability with the aid of chelation by a carbamoyl group to allow trapping before a complete racemization by bimolecular processes.
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Report
(4 results)
Research Products
(27 results)
