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

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. Graphical