Synthesis of β-enaminones in imidazolium ionic liquids

In this paper,a series of imidazolium ionic liquids with different anions and cations were prepared and the performance of these reaction medium for the synthesis of β-enaminones was investigated.The results showed that anion and cation had obvious effect on the performance of the ionic liquids.When anion was BF4-,the activity order of ionic liquids with different cations was [Hmim]+ [bmim]+,[emim]+ [bmmim]+.Among these reaction medium,[Hmim]BF4 exhibited the highest activity and had a yield of 96% after 10 min reaction.When cation was[Hmim]+,ionic liquids with a anion of BF4-,Tsa-,Br-and NO3-exhibited high activity and had a yield higher than 93% after 15 min reaction,while ionic liquid with HSO4-had a yield of 60% after 30 min.When cation was[bmim]+,the activity order was[bmim]Br [bmim]PF6 [bmim]BF4 and these three solvent/catalysts had a yield over 85%,while [bmim]HSO4 and [bmim]H2 PO4 ionic liquids presented a bad performance and had a yield below 70%.The [Hmim]BF4 was reused five times without considerable loss of activity and had a yield of 89% after 10 min.