Sonochemically synthesized copper chelate from expired streptomycin sulfate as a sustainable catalyst for green synthesis of 1,4-disubstituted triazoles in aqueous medium

This research work introduces a pioneering strategy for harnessing the potential of expired streptomycin sulfate as its copper chelate to catalyze the synthesis of biologically important 1,4-disubstituted-1,2,3-triazoles efficiently. The efficacy of this catalyst is showcased by the sonochemical 1,3-dipolar cycloaddition process, yielding 1,4-disubstituted-1,2,3-triazoles at 40 °C using a promotor ligand l-phenylalanine within 30 min in >90 % yield in aqueous media with high purity. The biocompatible promoter ligand assists the STR Cu chelate to enhance the reaction rate by stabilizing the Cu(I) oxidation state and preventing its undesirable disproportionation, thus increasing the yield of the intended product. The synthesized catalyst demonstrates extensive substrate compatibility and works equally well with precursors containing both electron donating and withdrawing groups (4–25). Additionally, all the synthesized compounds, as well as the catalyst, have been duly characterized by the usual analytical and spectroscopic techniques. Furthermore, the catalyst could be reused up to four cycles without a significant reduction in its catalytic performance.