1.2.5- Thiadiazoles biological properties

Section III deals with 1,2,5-thiadiazole 1,1-dioxides and fused systems. Other six-membered rings, such as thiatriazines and oxathiadiazines are gathered in Section IV, and Section V deals with miscellaneous compounds. Finally, in Section VI, the biological properties and other applications are described. 

Functionalization of Thiadiazole. Mesoionic compounds prepared on the 1,2,3-thiadiazolium scaffold have been studied for their chemical and biological properties and are known to display monoamine oxidase inhibitory activity. The reaction of 1,2,3-thiadiazole with /7-toluenesulfonic acid affords quantitative conversion to thiazolium /7-toluenesulfonate. The thiazolium tosylate can be reacted with sulfur in the presence of sodium hydride in DMF to afford the 5-thiolated mesoionic compound in 48% yield (eqs 1 and 2). ... 

The remarkable pestiddal properties of 1,2,4-thiadiazole derivatives, especially of organophosphorus compounds, and of 5-ethoxy-3-trichloro-methyl-1,2,4-thiadiazole and its analogs are the subject of brief separate Sections. Screening programs and individual studies continue3 to reveal a variety of other biological activities of 1,2,4-thiadiazoles. 

The N—N linkage of some of the hydrazine derivatives adds to their activity as agricultural chemicals because of their self-degradation mechanism. Thiadiazole is an example of this unique property, where the biological activeness of the compound is complemented by its self-destruct mechanism. 

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