pH-Responsive N-heterocyclic carbene copper(i) complexes: syntheses and recoverable applications in the carboxylation of arylboronic esters and benzoxazole with carbon dioxide

Abstract

A pH-controlled monophasic/biphasic switchable system has been developed as a green and novel strategy for homogeneous catalyst recycling, which has been successfully applied to the Cu-NHC-catalyzed carboxylation of organoboronic esters and benzoxazole with carbon dioxide. Additionally, the present strategy could also be extended to the Ag-NHC-catalyzed carboxylation of terminal alkyne. The tertiary amine-functionalized catalysts could be used for at least four times with a slight loss of activity.