Facile synthesis, crystal structure, quantum calculation, and biological evaluations of novel selenenyl sulfide compounds as potential agrochemicals

In order to design compounds with fresh molecular skeleton to break through the limitation of available agrochemicals, a series of 36 novel selenenyl sulfide compounds were chemically synthesized, and their biological activities were fully evaluated against tobacco mosaic virus (TMV), 14 plant pathogenic fungi, three insect species and plant acetohydroxyacid synthase (AHAS).All the target compounds were characterized by proton nuclear magnetic resonance (1 H-NMR), carbon-13 (13 C)-NMR, selenium-77 (77 Se)-NMR, and high-resolution mass spectrometry (HRMS). The crystal structure of 10j indicated that the Se-S bond was successfully constructed. Compounds 10d, 10h, 10s, 10u, 10aa, 10ac, 10ae, 10ag, and 10ai exhibited 40%, 43%, 39%, 41%, 47%, 46%, 47%, 42%, and 39% anti-TMV activities at 500 mg L-1 , better than that of ribavirin. The median effective concentration (EC50 ) against Sclerotinia sclerotiorum of 10ac was 6.69 mg L-1 and EC50 values against Physalospora piricola and Pyricularia grisea of 10z were 12.25 mg L-1 and 15.27 mg L-1 , respectively, superior to the corresponding values of chlorothalonil. Compounds 10c and 10v demonstrated 100% larvicidal activity against Culex pipiens pallens at 5 mg L-1 , while 10a displayed 100% insecticidal activity against Mythimna separata at 200 mg L-1 . Compounds 10c, 10j, and 10o showed > 60% inhibitions against plant AHAS at 10 μmol L-1 . From the quantum calculation, highest occupied molecular orbital (HOMO) was considered as a factor that affects the anti-TMV activity.The preliminary results suggested that more efforts should be devoted to exploring the selenenyl sulfides for the discovery of new leads of antiviral agent, fungicide, insecticide or AHAS inhibitors as potential agrochemicals for crop protection. © 2023 Society of Chemical Industry.