First Synthesis of the Novel Triazolo[3,4-b][1,3,4]Thiadiazoles and Triazolo[3,4-b][1,3,4]Thiadiazines Linked Chromeno[2,3-b]Pyridine

Abstract

The novel 3-(4-amino-5-thioxo-4,5-dihydro-1H-1,2,4-triazol-3-yl)-2H-chromeno[2,3-b]pyridine-2,5(1H)-dione (3) was efficiently synthesized from reaction of ethyl 2,5-dioxo-1,5-dihydro-2H-chromeno[2,3-b]pyridine-3-carboxylate (2) with thiocarbohydrazide. Compound 3 was utilize as building block for building a various heterocyclic systems linked chromeno[2,3-b]pyridine-2,5(1H)-dione. Reaction of compound 3 with some heterocyclic aldehydes afforded the condensation products 6 and 7. Treatment of compound 3 with some mono- and bi-electrophilic reagents afforded triazolo[3,4-b][1,3,4]thiadiazoles and triazolo[3,4-b][1,3,4]thiadiazines linked chromeno[2,3-b]pyridine, respectively. Finally, compound 3 reacted with 2,3-dichloroquinoxaline yielding the novel chromeno[2,3-b]pyridine bearing annulated triazolothiadiazinoquinoxaline 18. The obtained products were examined for their antimicrobial effectiveness appearing variable inhibitory action toward the used microorganisms.

Keywords:

• Chromeno[2,3-b]pyridine
• 4-amino-1,2,4-triazoles
• triazolo[3,4-b][1,3,4] thiadiazole
• triazolo[3,4-b
• ][1,3,4]thiadiazine
• heterocyclization
• nitrogen bridge head

Disclosure statement

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this article.