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Development of Various Cross-coupling Reactions in New Media for the Electron-Transfer Reactions

电子转移反应新介质中各种交叉偶联反应的发展

基本信息

批准号：
11450342
负责人：
TOKUDA Masao
金额：
$ 8.51万
依托单位：
Hokkaido University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2001
项目状态：
已结题

项目摘要

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.

本研究的目的是开发用于电子转移反应的新介质，并将这些介质用于各种有机卤化物与芳基卤化物的交叉偶联反应或选择性碳-碳形成反应。为了实现有效的交叉偶联反应，本研究采用了两种电子转移反应介质。一种是使用高反应性的锌，其可以通过电解容易地制备。另一种介质是使用活性金属阳极（如镁或锌）的电化学反应系统。我们发现，在萘存在下，用铂阴极和锌阳极电解含有支持电解质的DMF溶液，得到高活性锌（EGZn/Naph）。 EGZn/Naph 成功地将有机溴化物有效转化为相应的有机锌溴化物，有机锌溴化物与芳基碘化物溴化物在 Pd(II) 催化剂存在下反应，得到相应的交叉偶联产物，收率高。该方法还应用于非甾体抗炎药（例如布洛芬或萘普生）前体的有效合成。另一方面，我们发现当用铂阴极和镁或锌阳极使用菲作为介体进行芳基卤化物的电解时，发生向芳基卤化物的单电子转移，优先产生芳基自由基。由此产生的芳基自由基经历5-外环化形成分子内C-C双键。还进行了类似的由Bu_3SnH-AlBN产生的芳基环化以得到有用的生物碱。最后，我们发现二氧化碳与三氟甲磺酸乙烯酯的偶联反应或卤代炔丙酯与醛的偶联反应有效且选择性地发生，以良好的产率产生相应的羧酸或高丙二烯醇，而这些是通过常规合成方法不易获得的。