SiO2–NHC–Cu(I): an efficient and reusable catalyst for [3+2] cycloaddition of organic azides and terminal alkynes under solvent-free reaction conditions at room temperature

A novel SiO2–NHC–Cu(I) 3b was developed and used as a highly efficient catalyst for [3+2] cycloaddition of organic azides and terminal alkynes. In the presence of SiO2–NHC–Cu(I) 3b (1 mol %), the reactions of terminal alkynes with organic azides underwent smoothly to generate the corresponding regiospecific 1,4-disubstituted 1,2,3-triazoles in excellent yields under solvent-free reaction conditions at room temperature. Furthermore, catalyst 3b was quantitatively recovered from the reaction mixture by a simple filtration and reused for 10 cycles without loss of its activity.