Dialkyl imidazolium acetate ionosilica as efficient and recyclable organocatalyst for cyanosilylation reactions of ketones  

作　　者：Thanh Tran Duy Alysson Duarte Rodrigues Giang Vo-Thanh Peter Hesemann 

机构地区：[1]Institut de Chimie Moléculaire et des Matériaux D'Orsay,UniversitéParis-Saclay,UMR 8182,91405 Orsay Cedex,France [2]Institut Charles Gerhardt de Montpellier,Universitéde Montpellier,UMR 5253 CNRS-UM-ENSCM,Place E.Bataillon,34000 Montpellier,France

出　　处：《Green Energy & Environment》2020年第2期130-137,共8页绿色能源与环境（英文版）

基　　金：The authors thank the GDR LIPS#3585 for financial support.

摘　　要：We report new heterogeneous organocatalyst based on silica hybrid supported N-heterocyclic carbene(NHC-)species.The organocatalyst is formed from an imidazolium iodide based ionosilica material,followed by iodide/acetate anion exchange.The imidazolium acetate generates the organocatalytic carbene via partial deprotonation of the imidazolium ring in situ.As monitored via EDX,solid state NMR and ion chromatography measurements,the iodide/acetate exchange involving the imidazolium ionosilica material took place only in small extent.Despite the fact that the exchanged material contains only a very small amount of acetate,we observed good catalytic activity and recyclability in cyanosilylation reactions of ketones with trimethylsilyl cyanide.The versatility of the catalyst was highlighted via reaction with several substrates,yielding the corresponding cyanohydrins in good yields.In recycling experiments,the material showed decreasing catalytic activity starting from the third reaction cycle,but high catalytic activity can be regenerated via another acetate treatment.Our work is important as it highlights the possibility to combine carbene chemistry and silica,which are antagonistic at a first glance.We show that imidazolium acetate based ionosilicas are therefore heterogeneous'proto-carbenes',and that there is no need to form strongly basic silica supported NHCs to obtain heterogeneous NHC-organocatalysts.This work therefore opens the route towards heterogeneous and re-usable NHC-organocatalysts from supported ionic liquid imidazolium acetates.

关 键 词：N-heterocyclic carbenes Ionosilica Heterogeneous organocatalysis CYANOSILYLATION Ionic liquids 

分 类 号：O643.36[理学—物理化学]