Copper(I)-based ionic liquid-catalyzed carboxylation of terminal alltynes with CO2 at atmospheric pressure

An ionic liquid containing copper(I) proved to be an effective homogeneous catalyst for the carboxylation of terminal alkynes with ambient CO2. This developed procedure needs no external ligands and terminal alkynes with various groups proceeded smoothly at atmospheric CO2 pressure and room temperature. Interestingly, the ILs containing copper(I) in both the anion and the cation showed much higher activity in comparison with the counterparts incorporating copper(I) solely in the form of halocuprate, that is, copper(I) in the anion. Especially, activated effect of the terminal alkyne by the ionic liquid was also validated by the NMR technique. (C) 2015 Elsevier Ltd. All rights reserved.