Design, Synthesis, and Evaluation of X-ray Crystal Structure, Biological Activities, DFT Calculations, and Molecular Docking of Phenyl Imidazolidin-2-One Derivatives

Xile Deng,Yong Xie,Can Jin,Xiaomao Zhou,Junbo Gao

doi:10.3390/cryst10080713

Abstract

Eight phenyl imidazolinone derivatives were synthesized from N2-(2,4-dimethylphenyl)-N1-methyformamidine (DPMF) via scaffold-hopping method using the ring-closure approach. The prepared compounds were verified using 1H and 13C NMR and HRMS spectroscopies. The structure of compound 3c was confirmed by single-crystal X-ray diffraction analysis. The mean plane of the phenyl and imidazolinone moieties was almost coplanar with an angle of 8.85(4)°. In the crystal, molecules were interlinked with intermolecular hydrogen bonds (N–H···O and C–H···O), generating a network structure. Additionally, compound 3f displayed the highest insecticidal activity (86.7%) against Plutella xylostella at 600 mg/L, which was significantly higher than the insecticidal activity (23.0%) of DPMF. Also, compound 3d displayed good fungicidal activities against Phytophthora capsici, Phytophthora sojae, and Phytophthora infestans. Density functional theory (DFT) calculations were performed to explain the insecticidal and fungicidal activities of phenyl imidazolidin-2-one derivatives, especially potent compounds 3f and 3d. Moreover, the binding modes of compounds 3a–h and DPMF against octopamine receptor of Plutella xylostella were studied by homology modeling and molecular docking. Therefore, a preliminary structure–activity relationship (SAR) was derived and discussed. These results encourage the exploration of novel insecticides and fungicides based on DPMF.

Highlights

Octopamine receptors (OARs) are a class of G-protein coupled receptors (GPCRs) in invertebrates
Since OARs do not exist in humans, they are the potential targets for novel selective insecticides
This study offers useful guidance for the design and synthesis of new insecticides based on DPMF structure and provides the foundation for designing novel imidazolinone-type fungicides

Summary

Introduction

Octopamine receptors (OARs) are a class of G-protein coupled receptors (GPCRs) in invertebrates (e.g., insects). OARs can bind to octopamine (OA), and regulate physiological processes, such as reproduction, feeding, flight behaviors, memory, and learning [1,2,3,4]. Since OARs do not exist in humans, they are the potential targets for novel selective insecticides. Many compounds, such as plant oils, clonidine, naphazoline, yohimbine, chlorpromazine, and mianserin, have been identified as octopamine receptors’ agonists and antagonists. Further development as commercial insecticides has yet to be explored [5]. Formamidine insecticides, such as chlordimeform (Figure 1a) and amitraz (Figure 1b), have been launched on the market successfully

Methods

Results

Conclusion