Synthesis and pesticidal activity of new 1,3,4-oxadiazole thioether compounds containing a trifluoromethylpyrazoyl moiety

Abstract

In order to find new lead compounds with high pesticidal activity, a series of 1,3,4-oxadiazole thioether compounds ( 5 series) were designed by using penthiopyrad as a synthon. They were synthesized easily via five steps by using ethyl 4,4,4-trifluoro-3-oxobutanoate and triethyl orthoformate as starting materials. The synthesized compounds were characterized by 1 H NMR, 13 C NMR and HRMS. The compound 2-(benzylthio)-5-(1-methyl-3-(trifluoromethyl)-1 H -pyrazol-4-yl)-1,3,4-oxadiazole ( 5a ) was further determined by X-ray single-crystal diffraction. It crystallized in the monoclinic system, space group P2 1 /c , Z = 4. All the 1,3,4-oxadiazole thioether derivatives were screened for fungicidal activity against ten fungi and herbicidal activity against two weeds. The bioassay results indicated that some of the synthesized 1,3,4-oxadiazole compounds exhibited good fungicidal activity (> 50% inhibition) against the plant pathogens Sclerotinia sclerotiorum and Rhizoctonia solani at 50 μg/mL. Some of them exhibited certain herbicidal activity, and compounds 2-((3-chlorobenzyl)thio)-5-(1-methyl-3-(trifluoromethyl)-1 H -pyrazol-4-yl)-1,3,4-oxadiazole ( 5e) and 2-((4-bromobenzyl)thio)-5-(1-methyl-3-(trifluoromethyl)-1 H -pyrazol-4-yl)-1,3,4-oxadiazole (5 g) had bleach effect. Molecular docking is to find the best fit orientation of the 2-((4-bromobenzyl)thio)-5-(1-methyl-3-(trifluoromethyl)-1 H -pyrazol-4-yl)-1,3,4-oxadiazole (5 g) molecule with the SDH protein (PDB: 2FBW). The docking results indicate that the compound 5 g and the lead compound penthiopyrad have similar binding interactions with SDH and carbonyl is a key group for these compounds. Supplementary Information The online version contains supplementary material available at 10.1007/s11164-022-04839-x.

Substrate‐based synthetic strategies and biological activities of 1,3,4‐oxadiazole: A review

“…Shi et al. (2022) synthesized 2‐((3‐chlorobenzyl) thio)‐5‐(1‐methyl‐3‐(trifluoromethyl)‐1H‐pyrazol‐5‐yl)‐1,3,4‐oxadiazole 139 and 2‐((4‐bromobenzyl) thio)‐5‐(1‐methyl‐3‐(trifluoromethyl)‐1H‐pyrazol‐5‐yl)‐1,3,4‐oxadiazole 140 which were showing herbicidal activity. Compound 139 were found phytotoxicity against lettuce ( Lactuca sativa ) and bentgrass ( Agrostis stolonifera ) at 1 mM and compound 140 found the bleaching effect phenomenon against bentgrass at 1 mM.

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Design, synthesis, antifungal activity, and molecular docking of novel trifluoromethyl pyrimidine derivatives containing 1,3,4‐oxadiazole and thioether moieties as potential succinate dehydrogenase inhibitors

“…1,3,4-Oxadiazole, an important heterocyclic active fragment with significant pesticide biological activity, has attracted more and more attention of researchers for a long time [16][17][18][19][20][21]. Meanwhile, the previously studies had demonstrated that thioether derivatives had a broad spectrum of pesticide biological properties including antibacterial, antifungal, antiviral, and insecticidal activity [22][23][24][25][26].…”