二齿卡宾-三唑配体的五甲基环戊二烯基铱(III)配合物是氢借位介导的醇与胺偶联的优良均相催化剂。反应是高效的,在0.5 mol%的低催化剂负载下,在100°C下可在6小时内完成反应,而且对环境无害,唯一的副产物是水。铱(III)催化剂促进了一系列醇和胺底物(包括生物学相关基序)上C–N键的形成。与炭黑表面的共价连接产生了定义明确的“杂化”非均相催化剂,该催化剂在苯胺与苄醇的偶联反应中具有良好的转化成产物的能力,并且可以在没有催化剂浸出的情况下进行再循环。这代表了用于氢借用的碳上共价连接的异质铱催化剂的首次报道。发现非均相的周转数(TON)明显高于相应的均相反应。为了阐明均相反应机理,结合氘化实验的1 H NMR研究提出了一种机理。
Controlling the selectivity and efficiency of the hydrogen borrowing reaction by switching between rhodium and iridium catalysts
作者:Danfeng Wang、Roy T. McBurney、Indrek Pernik、Barbara A. Messerle
DOI:10.1039/c9dt02819f
日期:——
forming new carbon–carbon bonds. However, this transformation can result in more than one product being formed. The work reported here utilises bidentate triazole-carbene ligated iridium and rhodium complexes as catalysts for the selectiveformation of alkylated ketone or alcohol products. Switching from an iridium centre to a rhodium centre in the complex resulted in significant changes in product selectivity