1,3-Dipolar cycloaddition between dicarbonyl compounds and azides using CuO nanoparticles as a bifunctional catalyst

Motivated by the search for new efficient heterogeneous protocols for the preparation of biologically relevant heterocyclic scaffolds,1 herein we report the CuO nanoparticle-catalyzed synthesis of a wide range of 1,4,5- trisubstituted-1,2,3-triazoles via the 1,3-dipolar cycloaddition reaction between azides and carbonyl compounds.2 The developed protocol affords highly functionalized 1,2,3-triazoles in good to high yields, and catalyst can be easily recovered and reused in several reaction cycles after washing with a diluted basic solution. In addition, characterization techniques allowed us to get invaluable insights into the mechanism of the reaction and the deactivation of the catalyst; with basis in such data, a catalytic cycle was proposed, in which copper oxide’s amphoteric behavior allows it to act both as a base and a Lewis acid. We believe that the developed methodology represents a great advance in what regards the development of greener approaches for the synthesis of important biologically active compounds.