Silica immobilized copper N‐heterocyclic carbene: An effective route to 1,2,3‐triazoles via azide‐alkyne cycloaddition and multicomponent click reaction

A new silica supported copper N‐heterocyclic carbene (Cu‐NHC@SiO2) complex is prepared and characterized by scanning electron microscopy (SEM), energy dispersive X‐ray spectroscopy (EDX) and X‐ray photoelectron spectroscopy (XPS) analyses. This complex is an efficient and easily retrievable catalyst for 1,2,3‐triazole synthesis through direct azide‐alkyne cycloaddition reaction as well as one‐pot reaction using arylboronic acids. This catalytic system is also suitable for synthesis of 4‐aryl‐NH‐1,2,3‐triazoles from diverse benzaldehydes. Further, the catalyst can efficiently be recycled up to fifth cycle for all the three methods of 1,2,3‐triazole synthesis through direct azide‐alkyne cycloaddition and multi‐component reactions.