2000 Fiscal Year Final Research Report Summary
Development of new synthetic reactions based on the reactions of α, β-epoxysilanes and nucleophiles
| Project/Area Number |
10671986
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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 | Hiroshima University (2000)
Toyama Medical and Pharmaceutical University (1998-1999) |
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Principal Investigator |
TAKEDA Kei Hiroshima University, Faculty of Medicine, Professor, 医学部, 教授 (30135032)
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| Project Period (FY) |
1998 – 2000
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| Keywords | epoxysilanes / acylsilanes / eight-membered carbocycles / Brook rearrangement / asymmetric alkylation |
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| Research Abstract |
The objective of this study has been to develop new synthetic reactions based on the reaction of α, β-epoxysilanes with a nucleophile.
1. Stereospecific Construction of Eight-Membered Carbocycles
When γ-acryloylacylsilane was treated with vinyllithium, a cyclooctenone derivative was obtained as a single diastereomer via an anionic oxy-Cope rearrangement of 1, 2-divinylcyclobutanediol intermediate generated by way of Brook rearrangement of the 1, 2-adduct of the vinyllithium. Furthermore, we found a more versatile methodology for the synthesis of the carbocycles, which involves the reaction of γ-vinyl-γ-silyl-γ-lactones, prepared from β-methoxycarbonyacylsilane with vinyllithium, with vinyllithium.
2. Reaction of O-silyl Cyanohydrin derivatives of α, β-Epoxy-β-silylpropanal with Bases in the Presence of Alkylating Agents
Reaction of O-silyl cyanohydrin derivatives of α, β-Epoxy-β-silylpropanal with a strong base such as LDA, NHMDS in the presence of alkyl iodide afforded 2-alkylated derivatives of 2, 4-bis (siloxy)-3-butenenitrile as a single isomer in excellent yields. The fact that no O-alkylated and 4-alkylated products were obtained suggests that the tandem processes involving proton abstraction/epoxide ring opening/Brook rearrangement/allylic rearrangement/alkylation would occur in a concerted manner. The use of readily available optically active epoxides in the reaction seems very promising for construction of quaternary chiral centers and will be the subject of further studies.
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