The azide-alkyne cycloaddition catalysed by metal acetates

Azide-alkyne cycloadditions were performed in mild conditions in the presence of metal acetates, namely silver (I)- , nickel (II)- and cadmium (II) acetate as heterogeneous catalysts. The cycloaddition behaviour was dependent upon the metal acetate, the solvent and the azide mojety. With Ag (I) and Ni (II) acetates, mixtures of 4- and 5-substituted 1,2,3-triazoles were obtained with fair yields, while in the presence of Cd (II) acetate, regioselective cycloadditions to 4-substituted 1,2,3-triazoles occurred with high yields. Two concurrent intermediates were proposed in order to account all the experimental findings. The catalyst recovery was always easy to perform, and their reuse was also taken into account.