Research Progress of Oxadiazole/Thiadiazole Derivatives in the Discovery of New Agricultural Chemicals.

Oxadiazoles/thiadiazoles represent an important class of five-membered nitrogen heterocyclic active scaffolds. The remarkable structural diversity and multiple modifiable moieties of these compounds have enabled their widespread adoption in the discovery and development of new fungicides, antibacterial agents, antiviral agents, and insecticides. Oxadiazole/thiadiazole exists in four main structural isomeric forms, including 1,2,3-oxadiazole/thiadiazole, 1,2,4-oxadiazole/thiadiazole, 1,2,5-oxadiazole/thiadiazole, and 1,3,4-oxadiazole/thiadiazole. In recent years, numerous studies have been reported on oxadiazole/thiadiazole derivatives in the discovery of novel agrochemicals, especially 1,2,4-oxadiazole/thiadiazole and 1,3,4-oxadiazole/thiadiazole derivatives, which have fully demonstrated their broad application prospects in the field of new pesticide discovery. Accordingly, there is an urgent need for a systematic review of the research progress regarding oxadiazole and thiadiazole derivatives in the discovery of novel pesticidal agents. This work systematically summarizes the antibacterial, fungicidal, antiviral, insecticidal, and nematicidal activities of oxadiazole/thiadiazole derivatives and focuses on their structural modification patterns, structure-activity relationships (SARs), and the molecular mechanisms of action of representative compounds. This review aims to furnish novel research ideas to guide the rational design and development of next-generation agrochemicals.