Synthesis of novel derivatives of 1,2,3-triazole-linked pyrazole catalyzed by copper(I)

The synthesis of pyrazoles has attracted significant attention due to their pharmacological properties [1]. These derivatives possess a number of important biological roles. For instance, they exhibit anti-bacterial, anti-viral, anti-fungal, anti-histaminic, anti-cancer, anti-depressant, anti-inflammatory, anti-pyretic, and anti-convulsant activities[ 2,3]. Binding 1,2,3-triazole moieties to other pharmacophores via copper-catalyzed click reactions is important for the synthesis of biologically-active compounds. Copper-catalyzed azide-alkyne cycloaddition (CuAAC) reactions have several priorities over the thermal version including selectivity, increased reactivity of deactivated alkynes, and high yields. In this study, we decided to synthesize new derivatives of the 1,2,3-triazole-linked pyrazole ring system via the copper-catalyzed click reactions.A mixture of pyrazole (1), K2CO3, and propargyl bromide in DMF was stirred for 20 h at room temperature until the disappearance of the starting materials. The resulting solid substance was filtered to afford 3-methyl-1-propargyl-1H-pyrazol-5(4H)-one (2) in good yield. The click reaction of compound (2) with arylazides (3) in the presence of 10 mol% of CuSO4 and 20 mol% of sodium ascorbate at room temperature in EtOH, The desired products, 3-methyl-1-[(1-aryl-1H-1,2,3-triazol-4-yl)methyl]-1H-pyrazol-5(4H)-one (4) were obtained in good-to-high yields.