2004 Fiscal Year Final Research Report Summary
Development of Synthetic Organic Reactions Based on New Manganese Chemistry
| Project/Area Number |
15550166
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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 |
Organic industrial materials
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| Research Institution | University of Tsukuba |
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Principal Investigator |
HOJO Makoto University of Tsukuba, Graduate School of Pure and Applied Sciences, Associate Professor, 大学院・数理物質科学研究科, 助教授 (50229150)
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| Co-Investigator(Kenkyū-buntansha) |
HOSOMI Akira University of Tsukuba, Graduate School of Pure and Applied Sciences, Professor, 大学院・数理物質科学研究科, 教授 (00004440)
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| Project Period (FY) |
2003 – 2004
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| Keywords | manganese / Lewis acid / mixed reagent / alkoxide / iron catalyst / conjugated enyne / stereoselective |
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| Research Abstract |
It was found that manganese(II) salt accelerated cyclization of lithium 4-pentynyl alkoxides to give anionic cyclized intermediates, which reacted further with trifluoroacetic anhydride to afford acylated α-methylenetetrahydrofurans and dihydrofurans as a mixture. Each product could be obtained selectively choosing alkaline metal of alkoxide and reaction conditions. Besides trifluoroacetic anhydride, benzoyl bromide and ethylidenemalonate also reacted with the intermediate. This reaction enables both cyclization and introduction of their carbon-side chain of the cyclized intermediates in one-pot.
Organomanganates did not react with Lewis acid at lower temperature, and this mixture of organomanganate and Lewis acid converted acetals to the corresponding substitution product. Ketal also reacted with the "mixed reagent".
It was also found that alkyllithium reagents reacted with conjugated diynes in the presence of iron catalyst to give alkylated conjugated enynes. Alkylmagnesium reagents also afforded alkylated enynes. Interestingly, in the reaction of alkyllithium, the addition reaction proceeded in a manner of cis-addition, while the corresponding adduct, vinyilithium species isomerized to a cis-trans mixture under the equilibrium. When an ether functional group was in the diyne substrate, only trans-adduct was obtained, suggesting complete shift of the equilibrium to trans-adduct. Interestingly, Grignard reagents afforded only cis-adduct even in the reaction of diyne bearing an ether moiety. These vinyllithium and magnesium intermediates were very reactive, and reacted even with DMF and oxirans.
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