On the Dual Role of N-Heterocyclic Carbenes as Bases and Nucleophiles in Reactions with Organic Halides
作者:Axel Jacobi von Wangelin、Christiane Knappke、Anthony Arduengo, III、Haijun Jiao、Jörg-Martin Neudörfl
DOI:10.1055/s-0031-1289593
日期:2011.12
nucleophilicities, and sterics of N-heterocyclic carbenes have been studied in reactions of imidazolin-2-ylidenes with organic halides. Highly nucleophilic and less basic carbenes cleanly gave alkylideneimidazolines, the deoxy analogues of Breslow-type intermediates. More basic NHCs engaged in unwanted deprotonation or dehydrohalogenation reactions. N-heterocyclic carbenes - enamines - umpolung - imidazoles - nucleophilicity
已在咪唑啉-2-亚烷基与有机卤化物的反应中研究了N-杂环卡宾的不同碱性,亲核性和空间位阻的合成结果。高度亲核性和碱性较低的卡宾可以干净地得到亚烷基亚咪唑啉,这是Breslow型中间体的脱氧类似物。更多的碱性NHC参与不需要的质子化或脱氢卤化反应。 N-杂环卡宾-烯胺-乌泊隆-咪唑-亲核性