Design, Synthesis, Biological Activities, and 3D-QSAR of New N,N′-Diacylhydrazines Containing 2-(2,4-dichlorophenoxy)propane Moiety

A series of new N,N′-diacylhydrazine derivatives were synthesized efficiently under microwave irradiation. Their structures were characterized by 1H NMR, MS, and elemental analysis. Various biological activities of these compounds were tested. Most of them exhibited higher herbicidal activities against dicotyledonous weeds than monocotyledonous weeds. In addition, favorable in vivo fungicidal activities were also found of these compounds against Cladosporium cucumerinum, Corynespora cassiicola, Sclerotinia sclerotiorum(Lib.)de Bary, Erysiphe cichoracearum, and Colletotrichum orbiculare (Berk aLMont) Arx. All compounds displayed excellent plant growth regulatory activities: 100% inhibition was achieved against the radicle growth of cucumber. To further investigate the structure–activity relationship, comparative molecular field analysis was performed on the basis of herbicidal activity data, resulting in a statistically reliable model with good predictive power (r2 = 0.913, q2 = 0.556). Based on the calculation, five additional novel compounds were designed and synthesized. Satisfyingly, compound 4u displayed excellent herbicidal activity (94.7%) at 1500 g/ha, although it is less active than 2,4-D. Meanwhile, this compound also exhibited good fungicidal activity against C. orbiculare (Berk aLMont) Arx (82.16%).