Design, synthesis, herbicidal activity, and the molecular docking study of novel phenylpyrazole derivatives with strobilurin moieties

Phenylpyrazole derivatives were innovatively designed and synthesized to fabricate novel herbicides containing strobilurin moieties. These resulting compounds were analyzed by nuclear magnetic resonance spectroscopy (NMR) and high-resolution mass spectrometry (HRMS), exhibiting high herbicidal properties against Amaranthus retroflexus. The target compounds were synthesized through cyclization, chlorination, Vilsmeier-Hack reaction, Suzuki coupling reaction, and esterification reactions. The experimental conditions were mild, and the starting materials were easy to obtain, with a separation yield of approximately 80%. Moreover, herbicidal activity of the title compounds was studied <i>via</i> a pot culture experiment. Compounds 7a, 7b, 7e-7g, 7i, and 7l demonstrated good inhibition on <i>A</i>. <i>retroflexus</i>, which was inferior to that of fomesafen at 150 g a.i./hm². The docking results indicated that the binding energies of compound 7f with protoporphyrinogen oxidase (PPO) were both negative and spontaneous, with numerous interaction active sites. Thus, it is speculated that compound 7f is a PPO inhibitor.