Palladium-Catalyzed Carbon-Carbon Bond-Forming 1,2-Ligand Migration of Organoalanes

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• 作者：Eric Fillion ; Rebekah J. Carson ; Vincent E. Tré ; panier ; Julie M. Goll ; and Anna A. Remorova
• 刊名：Journal of the American Chemical Society
• 出版年：2004
• 出版时间：December 1, 2004
• 年：2004
• 卷：126
• 期：47
• 页码：15354 - 15355
• 全文大小：57K
• 年卷期：v.126,no.47(December 1, 2004)
• ISSN：1520-5126

文摘

A one-pot, two-step process that transforms terminal alkynes into ethyl methyl-substituted benzylic quaternary carbon centers is described. (E)-2,2-Disubstituted-1-alkenyldimethylalanes have been shown to participate in 1,2-alkyl migration from aluminum to carbon with concomitant arylation at the 2-position to furnish ethyl methyl-substituted benzylic quaternary carbon centers, when reacted intramolecularly with aryl halides and triflates in the presence of a Pd(0) catalyst. The protocol is initiated with Cp₂ZrCl₂-catalyzed methylalumination of terminal alkynes followed by palladium-catalyzed intramolecular arylation of the resulting (E)-2,2-disubstituted-1-alkenyldimethylalanes, leading to 1,2-methyl shift from aluminum to carbon. In that sequence, a total of three new C-C single bonds are made, and two of the three alkyl groups on Me₃Al transferred to the substrate on vicinal carbons. This method was applied to a variety of substrates, and the mechanism was investigated by deuterium-labeling experiments, which revealed that protodealumination of the final dialkylaluminum triflate or halide intermediates by CH₃CN results in the formation of the fourth bond in the course of the transformation.