Ionic Liquid as Catalyst and Reaction Medium: A Simple and Efficient Procedure for Paal–Knorr Furan Synthesis
作者:Gangqiang Wang、Zhi Guan、Rongchang Tang、Yanhong He
DOI:10.1080/00397910902978049
日期:2010.1.14
The ionicliquid 1-butyl-3-methyl-imidazolium hydrogen sulfate, [bmim]HSO4, efficiently catalyzes Paal–Knorr furan synthesis without any organic solvent. A wide range of aliphatic and aromatic 1,4-diketones easily undergo condensations to form furan derivatives, providing a general and convenient procedure. The Paal–Knorr reaction of ester-substituted 1,4-diketones is first reported. The ionic liquid
1-butyl-3-methyl-imidazolium hydrogen sulfate, [bmim]HSO4, was used as a catalyst and reaction medium for the pyrrolesynthesis, and a wide range of aliphatic, aromatic, heteroaromatic and carboxylic 1,4-diketones easily underwent condensations with aniline and ethylenediamine to form polysubstituted pyrroles. Sequential decarboxylation/Paal-Knorrpyrrolecondensation was observed, which provides a new
reaction of activemethylenecompounds, perfluoroalkyl iodides, and guanidines/amidines is reported. This constitutes a powerful method to prepare perfluoroalkylated pyrimidines with mild reaction conditions, broad substrate scope, excellent functional group tolerance, and simple operation. A radical/polar mechanism involving the formation of a halogen-bond adduct and radicalcross-coupling is proposed