Synthesis and Biological Evaluation of new 1,2,4-triazinones functionalized with mono-substituted pyrazole heterocycles

A new series of functionalized 1,2,4-triazinones (11a-g) were synthesized via 1,3-dipolar cycloaddition reactions of L-α-amino esters (1a-g) with N-(5-methyl-1H-pyrazol-3-yl) nitrile amine, generated in situ from the reaction of N-(5-methyl-1H-pyrazol-3-yl)-2-oxopropanehydrazonyl chloride (9) and triethyl amine. The structures of the newly synthesized compounds were confirmed by spectroscopic methods (HRMS, 1H-NMR, 13C-NMR and 2D-NMR). Furthermore, their antibacterial, antioxidant and antitumor activity were evaluated. The results clearly showed that compounds 11a,11d and 11e acted as highly active antioxidants; while on the other hand, all synthesized compounds exhibited a weak antitumor and antibacterial activity.