Cu2O spheres as an efficient source of catalytic Cu(I) species for performing azide-alkyne click reactions

We report herein the high yield synthesis of Cu₂O spheres displaying well-defined shapes and monodisperse sizes that could be employed as the source of highly catalytic active Cu(I) species towards click reactions between several of alkynes and azides to produce a variety of 1,2,3-triazoles under ligand-free and ambient conditions (in an open reactor). The utilization of Cu₂O spheres enabled superior performance as compared to a conventional protocol in which CuSO₄ is employed in combination with sodium ascorbate as the catalyst system. In addition, the compounds were obtained in synthetically useful yields, and seven of them have not been previously reported. We believe the results reported herein shed new insights into the optimization of activity and versatility of click reactions towards the synthesis of target molecules in environmentally friendly conditions.