2001 Fiscal Year Final Research Report Summary
Development of Various Cross-coupling Reactions in New Media for the Electron-Transfer Reactions
| Project/Area Number |
11450342
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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 |
Synthetic chemistry
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| Research Institution | Hokkaido University |
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Principal Investigator |
TOKUDA Masao Hokkaido Univ., Grad. School of Eng., Prof., 大学院・工学研究科, 教授 (80001296)
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| Co-Investigator(Kenkyū-buntansha) |
SENBOKU Hisanori Hokkaido Univ., Grad. School of Eng., Lec., 大学院・工学研究科, 助手 (50241360)
ORITO Kazuhiko Hokkaido Univ., Grad. School of Eng., Asso. Prof., 大学院・工学研究科, 助教授 (20109482)
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| Project Period (FY) |
1999 – 2001
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| Keywords | Highly reactive zinc / Organozinc compound / Cross-coupling / Anti-inflammatory agents / Radical cyclization / Electroorganic synthesis / Fixation of carbon dioxide / Reactive-metal anode |
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| Research Abstract |
The purpose of this study is to develop new media for the electron-transfer reactions and to use these media in cross-coupling reactions of various organic halides with aryl halides or in selective carbon-carbon forming reactions. In order to achieve efficient cross-coupling reactions, two media for the electron-transfer reactions were employed in this study. One is to use highly reactive zinc which can readily be prepared by electrolysis. Another medium is the electrochemical reaction system using a reactive-metal anode such as magnesium or zinc.
We found that the electrolysis of a DMF solution containing supporting electrolyte in the presence of naphthalene with a platinum cathode and a zinc anode gave the highly reactive zinc (EGZn/Naph). The EGZn/Naph was successfully used for efficient transformation of organic bromides to the corresponding organozinc bromides, which were reacted with aryl iodides bromides in the presence of Pd(II) catalyst to give the corresponding cross-coupled products high yields. This methodology was also applied to an efficient synthesis of the precursors of non-steroidal anti-inflammatory agents such as ibuprofen or naproxen. On the other hand, we found that a one-electron transfer to aryl halides occurred to give preferentially aryl radicals when the electrolysis of aryl halides was carried out with a platinum cathode and a magnesium or zinc anode using phenanthrene as a mediator. Aryl radicals thus generated underwent 5-exo cyclizations to intramolecular C-C double bond. Similar cyclization of aryl radicals generated by Bu_3SnH-AlBN to give useful alkaloids was also carried out. Finally, we found that coupling reactions of carbon dioxide with vinyl trifiates or those of propargylic halides with aldehydes took place efficiently and selectively to give the corresponding carboxylic acids or homoallenyl alcohols, not readily available by conventional synthetic methods, in good yields.
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