Design, Synthesis And Biological Activity Study Of 1,3,4-oxadiazole Compounds Containing Sulfonate/carboxylate Structure

In this paper,starting from ethyl glycolate,the target compounds 4/5 were obtained by acylation,cyclization,thioetherification,and acylation.The structures of all target compounds were confirmed by ¹H NMR,¹³C NMR,¹⁹F NMR and ESI-HRMS.The single crystal of compound 4b was cultured and analyzed by single-crystal X-ray diffraction.Antibacterial activity against two phytopathogens,Xanthomonas oryzae pv.oryzae and Xanthomonas axonopodis pv.citri,was assayed in vitro.The preliminary results indicated that ten compounds including 4a-4d and 4k-4p had good antibacterial activity against Xoo,with EC50 values ranging from 50.1-112.5μM,which was better than those of Bismerthiazol（253.5μM）and Thiodiazole copper（467.4μM）.Meanwhile,4a,4b,4c and 4d demonstrated good inhibitory effect against Xanthomonas axonopodis pv.citri with EC50 values around 95.8-155.2μM which were better than those of bismerthiazol（274.3μM）and thiodiazole copper（406.3μM）.In addition,in vivo protection activity of compound 4b and 4c against rice bacterial leaf blight was 68.6%and 62.3%,respectively,which were better than bismerthiazol（49.6%）and thiodiazole copper（42.2%）.Curative activity of compound 4a,4b and 4c against rice bacterial leaf blight was 44.6%,62.3%and 56.0%,which were better than bismerthiazol（42.9%）and thiodiazole copper（36.1%）.Through scanning electron microscopy（SEM）analysis,it was observed that compound 4b caused the cell surface of Xoo ruptured or deformed.It was confirmed that compound 4b played an antibacterial effect.We also tested the insecticidal activity of the compounds against Meloidogyne incognita.At the concentration of 10μg/m L,the lethality of the test compounds did not exceed 8%compared with the 100%lethality of the control drug avermectin.