the presence of a trinuclear metal complex activated by a carboxylicacid is presented. The triplatinum catalyst enables the cyclization of the substrate and subsequent incorporation of a nucleophile in the final product. In contrast, sequential cyclization/double bond shift occurs under analogous conditions in the presence of the corresponding tripalladium complex. The distinct reactivity of 1,6-enynes
Gold(I)-Catalyzed Intramolecular Cyclopropanation of Dienynes
作者:Cristina Nieto-Oberhuber、Salomé López、M. Paz Muñoz、Eloísa Jiménez-Núñez、Elena Buñuel、Diego J. Cárdenas、Antonio M. Echavarren
DOI:10.1002/chem.200501089
日期:2006.2.8
Gold(I) complexes are the most active catalysts for the biscyclopropanation of dienynes to form tetracyclic compounds. PtII and ZnII are also able to promote the biscyclopropanation, although less efficiently. The configurations obtained in all cases with the use of gold(I) catalysts can be explained by the pathway proceeding through anti cyclopropyl goldcarbenes. Similar intermediates are most probably
Generation of α‐Boryl Radicals by H
<sup>.</sup>
Transfer and their Use in Cycloisomerizations
作者:Shicheng Shi、Farbod Salahi、Hunter B. Vibbert、Maleeha Rahman、Scott A. Snyder、Jack R. Norton
DOI:10.1002/anie.202107665
日期:2021.10.11
Carbon-centered radicals can be stabilized by delocalization of their spin density into the vacant p orbital of a boron substituent. α-Vinyl boronates, in particular pinacol (Bpin) derivatives, are excellent hydrogen atom acceptors. Under H2 , in the presence of a cobaloxime catalyst, they generate α-boryl radicals; these species can undergo 5-exo radical cyclizations if appropriate double bond acceptors
以碳为中心的自由基可以通过将其自旋密度离域到硼取代基的空 p 轨道中来稳定。α-乙烯基硼酸酯,特别是频哪醇(Bpin)衍生物,是优异的氢原子受体。在H2下,在钴肟催化剂存在下,它们生成α-硼基自由基;如果存在适当的双键受体,这些物质可以进行 5-exo 自由基环化,从而在 Bpin 上形成带有叔取代基的密集官能化杂环。该反应表现出良好的官能团耐受性和广泛的范围,所得硼酸酯产物可以转化为其他有用的官能团。
Cationic Gold(I) Complexes: Highly Alkynophilic Catalysts for theexo- andendo-Cyclization of Enynes
作者:Cristina Nieto-Oberhuber、M. Paz Muñoz、Elena Buñuel、Cristina Nevado、Diego J. Cárdenas、Antonio M. Echavarren