Selenium Dioxide–Mediated Synthesis of Fused 1,2,4-Triazoles as Cytotoxic Agents

Abstract

A series of fused 1,2,4-triazoles has been prepared by oxidative intramolecular cyclization of heterocyclic hydrazones with selenium dioxide. General applicability of this practical protocol was confirmed by the synthesis of moderate to good yields of 1,2,4-triazolo[4,3-a]pyridines, 1,2,4-triazolo[4,3-a]pyrimidines, 1,2,4-triazolo[4,3-a]pyramidines, and 1,2,4-triazolo-[4,3-a]quinoxa lines. All compounds were tested in vitro for their cytotoxic activity against HCT-116, A549, and Colo-205 cell lines. Two compounds, 3-(4-methoxyphenyl)-7-methyl-[1,2,4]triazolo[4,3-a]pyridine and 1-(4-methoxyphenyl)-[1,2,4]triazolo[4,3-a]quinoxaline, showed potent antiproliferative activity against the three cell lines.

GRAPHICAL ABSTRACT

Keywords:

• Antiproliferative activity
• selenium dioxide
• 1,2,4-triazole

SUPPLEMENTAL MATERIAL

Experimental procedures, ¹H NMR and ¹³C NMR spectra data, and references for all the products for this article can be accessed on the publisher’s website.