Advanced Olefination via Ynolates
| Project/Area Number |
17390006
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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 | Kyushu University |
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Principal Investigator |
SHINDO Mitsuru Kyushu University, Institute for Materials Chemistry and Engineering, Associate Professor, 先導物質化学研究所, 助教授 (40226345)
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| Project Period (FY) |
2005 – 2006
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| Project Status |
Completed (Fiscal Year 2006)
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| Budget Amount *help |
¥15,200,000 (Direct Cost: ¥15,200,000)
Fiscal Year 2006: ¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 2005: ¥11,600,000 (Direct Cost: ¥11,600,000)
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| Keywords | ynolate / olefination / ester / orbital interaction / enol ether / germanium / torquoselectivity / Nazarov reaction / オレフィン化 / torquoselectivity / ケトン / ホモロゲーション |
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| Research Abstract |
We have been developing new synthetic reactions utilizing ynolates. Over the last few years, we have developed the torquoselective olefination of aldehydes, ketones and acylsilanes with ynolates^4 via ring-opening of β-lactone enolates. In this research project, we focused on the advanced olefination of carbonyl compounds using ynolates.
1) Olefination of ester carbonyls and the application to organic syntheses : Conventional methods generally have been unsuccessful in realizing olefination of ester carbonyls due to the lower electrophilicity of esters. We succeeded in the first highly stereoselective synthesis of tetrasubstituted, functionalized (E)-enol ethers via olefination of esters with ynolates. Ynolates add to alkyl esters at room temperature to provide the enol ethers with exclusive E-selectivities in good to excellent yields.
2) The Nazarov reaction : The enol ethers were converted into β-alkoxy divinylketones in three steps. These ketones are subjected to the Nazarov reaction
… More
catalyzed by various kinds of acids. Consequently, the reaction completed within minutes to afford α-alkoxy cyclopentenones in excellent yields using super acids as well as Lewis acids. Especially trifluoromethanesulfonic acid is found to be an excellent catalyst. The elimination of the β-alkoxy group seems to be a driving force of the reaction and controls the regioselectivity.
3) Olefination of a-alkoxyketones : We found the highly Z-selective olefination of α-alkoxy ketones with ynolates. Several experimental results and theoretical calculations suggested the hyperconjugate effect which is orbital interactions between σ-orbital of the breaking C-O bond and σ^*-orbital of C-O bond of the side chain. This is also torquoselective olefination.
4) Torquoselective olefination of acylgermanes : The first highly Z-selective olefination of acylgermanes with ynolates affording multisubstituted alkenylgermanes was achieved. The torquoselectivity was ascribed to the hyperconjugative effect of C-Ge bonds in the transition state. The resulting (Z)-β-trialkylgermylacrylic acid has a hypervalent struct ure, which was converted into novel germalactones. A stereochemical complementary olefination via protonation of the β-lactone enolate, followed by decarboxylation, was also achieved Less
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Report
(3 results)
Research Products
(28 results)
