Synthesis and Biological Activities of Novel (Z)‐/(E)‐Anisaldehyde‐Based Oxime Ester Compounds

Abstract In search of novel natural product‐based bioactive molecules, twenty (ten pairs) novel ( Z )‐/( E )‐anisaldehyde‐based oxime ester compounds were designed and synthesized by using anisaldehyde as starting material. Structural characterization of the target compounds was carried out by NMR, FT‐IR, ESI‐MS, and elemental analysis. Their herbicidal and antifungal activities were preliminarily tested. As a result, at 50 μg/mL, compound ( E )‐ 5b exhibited excellent to good inhibition rates of 92.3 %, 79.2 %, and 73.9 %, against Rhizoctonia solani , Fusarium oxysporum f. sp. cucumerinum , and Bipolaris maydis , respectively, better than or comparable to that of the positive control chlorothalonil. In addition, at 100 μg/mL, compounds ( E )‐ 5b , ( E )‐ 5f , ( Z )‐ 5f and ( E )‐ 5d exhibited excellent to good inhibition rates of 85.8 %, 82.9 %, 78.6 % and 64.2 %, respectively, against the root‐growth of rape ( B. campestris ), much better than that of the positive control flumioxazin. The bioassay result also showed that the synthesized compounds had obvious differences in antifungal and herbicidal activities between ( Z )‐ and ( E )‐isomers. Preliminary structure–activity relationship was also discussed by theoretical calculation.