Regioselective formation of new 3-<i>S</i>-alkylated-1,2,4-triazole-quinolones

Regioselective synthesis of quinolone-1,2,4-triazoles was established starting from 4-hydroxyquinol-2-ones. The strategy started by the reaction ethyl bromoacetate with 4-hydroxyquinoline to give corresponding oxoquinolinyl acetates, which reacted hydrazine hydrate afford hydrazide derivatives. Subsequently, hydrazides isothiocyanate derivatives acyl thiosemicarbazides. Finally, subjecting thiosemicarbazide bromoacetate, underwent internal cyclization and alkylation processes. Alkylation occurred regioselectivity sulfur atom thione group not amino group. Thus 3-S-1,2,4-triazole-quinolones were obtained in good yields. structure compounds proved different spectroscopic techniques together elemental analysis X-ray crystallography.Highlights Synthesis novel quinoline-2-one/1,2,4-triazole hybrids four steps.NMR, IR mass spectra crystallography 3-S-alkylated-1,2,4-triazole-quinolones excluded formation 2-N-alkylated-1,3,4-thiadiazole-quinolones.Plausible mechanism for targeted suggested.