在催化量的1,2-二取代或1,2,3-三取代的咪唑鎓盐的存在下,γ-取代的烯丙基氯与烷基格氏试剂反应,以S N 2'-选择性方式进行取代反应,其中假定将原位生成的咪唑-2-亚胺或咪唑-4-亚胺的镁盐配合物[(N-杂环卡宾-MgR 3)-(MgX)+ ]作为活性物质。观察到与咪唑-4-亚烷基催化剂的反应比与咪唑-2-亚烷基催化剂的反应更快。初步研究了使用手性咪唑盐的对映选择性催化。
Preparation of a Series of “Ru(<i>p</i>-cymene)” Complexes with Different N-Heterocyclic Carbene Ligands for the Catalytic β-Alkylation of Secondary Alcohols and Dimerization of Phenylacetylene
A series of five different "(p-cymene)Ru(NHC)" complexes (NHC = imidazolin-2-ylidene, imidazolin-4-ylidene, and pyrazolin-3-ylidene) have been obtained and fully characterized. The crystal structure of two of the new complexes has been determined by X-ray diffraction methods. All five complexes have been tested in the catalytic beta-alkylation of secondary alcohols with primary alcohols and the dimerization of phenyl acetylene, showing an excellent activity in both processes. A clear improvement on the catalytic activity of the complexes is observed when the more basic NHC ligands are used. The pyrazolylidene-Ru complex lies among the best catalysts for the beta-alkylation of secondary alcohols reported to date.
New Insights Into the Role of Imidazolium-Based Promoters for the Electroreduction of CO<sub>2</sub> on a Silver Electrode
作者:Genevieve P. S. Lau、Marcel Schreier、Dmitry Vasilyev、Rosario Scopelliti、Michael Grätzel、Paul J. Dyson
DOI:10.1021/jacs.6b03366
日期:2016.6.29
The electrochemical reduction of CO2 to CO is a reaction of central importance for sustainable energy conversion and storage. Herein, structure activity relationships of a series of imidazolium-based cocatalysts for this reaction are described, which demonstrate that the C4- and C5-protons on the imidazolium ring are vital for efficient catalysis. Further investigation of these findings led to the discovery of new imidazolium salts, which show superior activity as cocatalysts for the reaction, i.e., CO is selectively produced at significantly lower overpotentials with nearly quantitative faradaic yields for CO.
Cu-catalyzed controllable C–H mono-/di-/triarylations of imidazolium salts for ionic functional materials
作者:Shiqing Li、Junbin Tang、Yinsong Zhao、Ruyong Jiang、Tianbao Wang、Ge Gao、Jingsong You
DOI:10.1039/c7cc01076a
日期:——
The first Cu-catalyzed direct C-H mono-, di- and triarylations of imidazolium salts with aryl iodides/bromides are reported.