Iron-Copper Cooperative Catalysis in the Reactions of Alkyl Grignard Reagents: Exchange Reaction with Alkenes and Carbometalation of Alkynes
Iron-Copper Cooperative Catalysis in the Reactions of Alkyl Grignard Reagents: Exchange Reaction with Alkenes and Carbometalation of Alkynes
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DOI：
10.1021/ja206745w
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发表时间：
2012-01-11
影响因子：
15
通讯作者：
Hayashi, Tamio
中科院分区：
文献类型：
--
作者：
Shirakawa, Eiji;Ikeda, Daiji;Hayashi, Tamio
铁-铜协同催化对烯烃-格氏交换反应和炔烃的烷基镁化反应有效。 FeCl3 (2.5 mol%) 和 CuBr (5 mol%) 与 PBu3 (10 mol%) 结合催化末端烯烃 (RCH=CH2) 和环戊基溴化镁之间的格氏交换，以高产率得到 RCH2CH2MgBr。 1-烷基格氏试剂在由 Fe(acac)(3)、CuBr、PBu3 和 N,N,N',N'-四甲基乙二胺组成的催化剂体系存在下添加到炔烃中，得到 β-烷基乙烯基格氏试剂。交换反应和碳金属化发生在铁上，而铜通过与有机铁和有机镁物质之间的金属转移来协助有机基团的交换。通过向第一个反应的混合物中添加炔烃，成功地进行了由烯烃-格氏交换和炔烃的烷基镁化组成的连续反应。由 Fe-Cu 催化的格氏试剂从 2-烷基异构化为 1-烷基也适用于第一个 1-烷基格氏试剂形成步骤。
Iron-copper cooperative catalysis is shown to be effective for an alkene-Grignard exchange reaction and alkylmagnesiation of alkynes. The Grignard exchange between terminal alkenes (RCH=CH2) 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',N'-tetramethylethylenediamine to give beta-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-Grignard 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-Cu also is applicable as the first 1-alkyl Grignard formation step.