Short Communication Synthesis and Cytotoxic Assessment of Thieno pyridine Derivatives

Thieno[2,3-b]pyridine, a bicyclic heterocyclic, possesses various advantageous biological properties, including a cytotoxic effect. This study synthesized thieno pyridine scaffold derivatives with position 2 modifications. The reaction between 2-chloronicotinonitrile and methyl thioglycolate produced methyl amino thieno pyridine carboxylate 1. As a result of hydrazinolysis, methyl amino thieno pyridine carbohydrazide 2 was synthesized as a key compound for preparing final derivatives. The reaction of compound 2 with phthalic anhydride yielded thieno pyridine-phthalimide. The 1,3,4-oxadiazole scaffolds were synthesized in two steps. During the initial reaction of compound 2 with aroyle chloride derivatives, the corresponding intercessor was cyclized to oxadiazole in the presence of phosphoryl chloride. Compound 2 was subsequently cyclized in boiling glacial acetic acid to produce a pyridine-pyrazole derivative. MTT assay was utilized to assess the cytotoxic activity against two cell lines. Except for compound 6, the final compounds exhibited IC50 values <50 µM against both cell lines. Lipophilic compounds 4 and 5 exhibited significant cytotoxic effects compared to other compounds.