7-(2-aryl-1-cyanovinyl)-1,2,3,4-tetrahydropyrazolo[1,5-<i>a</i>][1,3,5]triazine-8-carbonitriles: synthesis and biological activity

Abstract

A new method was proposed for the preparation of 5-amino-3-(cyanomethyl)-1 H -pyrazole-4-carbonitrile by reacting the potassium salt of malononitrile dimer with hydrazinium sulfate. The reaction of 5-amino-3(cyanomethyl)-1 H -pyrazole-4-carbonitrile with aromatic aldehydes in the presence of catalytic amounts of morpholine leads to the formation of Knoevenagel condensation products. Aminomethylation of the resulting ( Z )-5amino-3-(2-aryl-1-cyanovinyl)-1 H -pyrazole-4-carbonitriles with primary aromatic amines and excess aqueous HCHO in refluxing DMF leads to the formation of 7-(2-aryl-1-cyanovinyl)-1,2,3,4-tetrahydropyrazolo[1,5- a ][1,3,5]triazine-8-carbonitriles. Bioavailability parameters were studied in silico , and possible protein targets were predicted by protein-ligand docking. In an in vitro experiment on cultures of E. coli , S. aureus and B. pumilis , 5-amino-3-(cyanomethyl)-1 H -pyrazole-4-carbonitrile does not show any noticeable antibacterial effect. At the same time, three compounds of the pyrazolo[1,5- a ][1,3,5]triazine series showed a pronounced antidote effect against the herbicide 2,4-D on sunflower seedlings in a laboratory experiment, for one compound a noticeable growth-stimulating effect was noted.