Abstract
To discover new compounds with broad spectrum and high activity, we designed a series of novel benzamides containing 1,2,4-oxadiazole moiety by bioisosterism, and 28 benzamides derivatives with antifungal activity were synthesized. These compounds were evaluated against four fungi: Botrytis cinereal, FusaHum graminearum, Marssonina mali, and Thanatephorus cucumeris. The results indicated that most of the compounds displayed good fungicidal activities, especially against Botrytis cinereal. For example, 10a (84.4%), 10d (83.6%), 10e (83.3%), 10f (83.1%), 10i (83.3%), and 10l (83.6%) were better than pyraclostrobin (81.4%) at 100 mg/L. In addition, the acute toxicity of 10f to zebrafish embryo was 20.58 mg/L, which was classified as a low-toxicity compound.
Highlights
Chemical pesticides play a vital role in solving food problems
Diamide insecticides have attracted a lot of attention due to their novel mechanism of action, high efficiency, and low toxicity [32–42]
According to the principle of bioisosterism [45,46], we searched for the amide group of broflanilide in the 1,2,4-oxadiazole ring, replaced the benzene ring with a pyridine structure containing a thioether derivative, and designed (Figure 2) and synthesized (Scheme 1) a series of novel benzamides substituted with 1,2,4-oxadiazole
Summary
Chemical pesticides play a vital role in solving food problems. as people’s environmental awareness gradually deepens, high-efficiency, low-toxicity, and environmentally friendly pesticides have become an inevitable trend in the creation of new pesticides [1–3]. According to the principle of bioisosterism [45,46], we searched for the amide group of broflanilide in the 1,2,4-oxadiazole ring, replaced the benzene ring with a pyridine structure containing a thioether derivative, and designed (Figure 2) and synthesized (Scheme 1) a series of novel benzamides substituted with 1,2,4-oxadiazole. These new compounds were confirmed by 1H NMR, 13C NMR, and HRMS, and their insecticidal activities, fungicidal activities, and toxicity test of zebrafish embryo were studied. Reagents and conditions: (a) DMS, K2CO3, acetone, reflux; (b) CH3CH2SH, KTB, DMF, 0–5 ◦C, rt; (c) THF, OH-, reflux; (d) CH3OH, H+, reflux; (e) CuCN, L-proline, DMF, 100 ◦C; (f) NH2OHHCl, CH3CH2OH, rt; (g) SOCl2, reflux; Et3N, toluene, reflux; (h) THF, OH-, reflux; (i) EDCI, Et3N, CH2Cl2, rt; (j) mCPBA, CH2Cl2, rt
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