Iron鈥揅opper Cooperative Catalysis in the Reactions of Alkyl Grignard Reagents: Exchange Reaction with Alkenes and Carbometalation of Alkynes

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• 作者：Eiji Shirakawa ; Daiji Ikeda ; Seiji Masui ; Masatoshi Yoshida ; Tamio Hayashi
• 刊名：The Journal of the American Chemical Society
• 出版年：2012
• 出版时间：January 11, 2012
• 年：2012
• 卷：134
• 期：1
• 页码：272-279
• 全文大小：521K
• 年卷期：v.134,no.1(January 11, 2012)
• ISSN：1520-5126

文摘

Iron鈥揷opper cooperative catalysis is shown to be effective for an alkene鈥揋rignard exchange reaction and alkylmagnesiation of alkynes. The Grignard exchange between terminal alkenes (RCH鈺怌H₂) and cyclopentylmagnesium bromide was catalyzed by FeCl₃ (2.5 mol %) and CuBr (5 mol %) in combination with PBu₃ (10 mol %) to give RCH₂CH₂MgBr in high yields. 1-Alkyl Grignard reagents add to alkynes in the presence of a catalyst system consisting of Fe(acac)₃, CuBr, PBu₃, and N,N,N鈥?N鈥?tetramethylethylenediamine to give 尾-alkylvinyl Grignard reagents. The exchange reaction and carbometalation take place on iron, whereas copper assists with the exchange of organic groups between organoiron and organomagnesium species through transmetalation with these species. Sequential reactions consisting of the alkene鈥揋rignard exchange and the alkylmagnesiation of alkynes were successfully conducted by adding an alkyne to a mixture of the first reaction. Isomerization of Grignard reagents from 2-alkyl to 1-alkyl catalyzed by Fe鈥揅u also is applicable as the first 1-alkyl Grignard formation step.