Fused systems combining 1,2,4-triazole and 1,3,4-thiadiazole rings occupy a prominent place in modern bioorganic and medicinal chemistry due to the diverse range of their biological activities. Thus, compounds incorporating [1,2,4]triazolo[3,4-b]thiadiazole ring system are of essential importance and particular interest both in the pharmaceutical as well as agrochemical industries. Herein, an overview of certain synthetic methodologies for obtaining of heterocyclic compounds based on functionally substituted 1,2,4-triazolo[3,4-b][1,3,4]thiadiazoles are presented.

Triazolo[3,4-b]thiadiazoles are a class of heterocyclic compounds, which have attracted great interest in medicinal chemistry owing to their wide range of pharmacological activities. A number of triazoles fused to thiadiazoles are incorporated into a wide variety of therapeutically important compounds possessing a broad spectrum of biological activities. Considering such a significant pharmacological potential, as well as wide synthetic possibilities triazolo-thiadiazoles have received considerable attention from scientific community and are extensively used for construction of prospective drug-likes molecules. In this review, we summarized the literature data about the main synthetic approaches for obtaining condensed heterocyclic compounds based on triazolo[3,4-b][1,3,4]thiadiazole scaffold as promising objects for modern bioorganic and medicinal chemistry. 

The present microreview provides a systematic and illustrative overview of the most typical methods for the synthesis of new thiazolo[3,2-a]pyridines. The material covers key works published since 2020.