In Situ Generation of Copper Nanoparticles by Rongalite and Their Use as Catalyst for Click Chemistry in Water

Abstract

A novel, efficient and green protocol for the copper-catalyzed azide–alkyne cycloaddition (CuAAC) reaction by using copper nanoparticles (CuNPs), generated in situ by a green reducing agent, rongalite, is reported. Terminal alkynes reacted with benzyl, aryl and alkyl azides in the presence of copper nanoparticles and β -cyclodextrin (β-CD) in water. The reactions exclusively generated the corresponding regiospecific 1,4- disubstituted 1,2,3-triazoles in good to excellent yields. Notably, in situ generation of copper nanoparticles does not require any additional stabilizing agents or special reaction conditions. β- cyclodextrin plays dual role as a stabilizing agent as well as phase transfer catalyst. This protocol is also applicable for gram scale reactions.