Fabian León Rayo David, Hong Young J, Campeau Dominic, Tantillo Dean J, Gagosz Fabien
Department of Chemistry and Molecular Sciences, University of Ottawa, K1N 6N5, Ottawa, Canada.
Department of Chemistry, University of California - Davis Davis, California, 95616, United States.
Chemistry. 2021 Jul 21;27(41):10637-10648. doi: 10.1002/chem.202100580. Epub 2021 May 27.
Gold-catalyzed dehydro-Diels-Alder reactions of ynamide derivatives allow efficient access to a variety of N-containing aromatic heterocycles. A dual gold catalysis mechanism was postulated for transformations involving the formation of C-C bonds by reaction between a terminal alkyne and an enynamide fragment. In this article, complete experimental and computational investigations into the mechanism of such a transformation are reported. Support for a dual gold catalysis was found and it was shown that the concerted or stepwise nature of the cyclization event depends on the substitution of the ynamide moiety. The reaction was found to proceed in three stages: 1) formation of a σ,π-digold complex from the terminal alkyne, 2) cyclization to produce a gem-diaurated aryl complex, and 3) catalyst transfer to free the product and regenerate the σ,π-digold complex.
烯酰胺衍生物的金催化脱氢狄尔斯-阿尔德反应能够高效合成多种含氮芳香杂环化合物。对于涉及末端炔烃与烯酰胺片段反应形成碳-碳键的转化反应，推测存在双金催化机制。本文报道了对此类转化反应机理的完整实验和计算研究。研究发现了双金催化的证据，并表明环化反应的协同或分步性质取决于烯酰胺部分的取代情况。该反应分三个阶段进行：1）由末端炔烃形成σ,π-双金配合物；2）环化生成偕二金芳基配合物；3）催化剂转移以释放产物并再生σ,π-双金配合物。
