Novel Dioxolane Ring Compounds for the Management of Phytopathogen Diseases as Ergosterol Biosynthesis Inhibitors :Synthesis, Biological Activities, and Molecular Docking

Thirty novel dioxolane ring compounds were designed and synthesized. Their chemical structures were confirmed by1H NMR, HRMS, and single crystal X-ray diffraction analysis. Bioassays indicated that these dioxolane ring derivatives exhibitedexcellent fungicidal activity againstRhizoctonia solani,Pyricularia oryae,Botrytis cinerea,Colletotrichum gloeosporioides,Fusariumoxysporum,Physalospora piricola,Cercospora arachidicolaand herbicidal activity against lettuce (Lactuca sativa), bentgrass (Agrostisstolonifera), and duckweed (Lemna pausicostata). Among these compounds, 1-((2-(4-chlorophenyl)-5-methyl-1,3-dioxan-2-yl)methyl)-1H-1,2,4-triazole (D17), 1-(((4R)-2-(4-chlorophenyl)-4-methyl-1,3-dioxolan-2-yl)methyl)-1H-1,2,4-triazole (D20), 1-((5-methyl-2-(4-(trifluoromethyl)phenyl)-1,3-dioxan-2-yl)methyl)-1H-1,2,4-triazole (D22), and 1-((2-(4-fluorophenyl)-1,3-dioxo-lan-2-yl)methyl)-1H-1,2,4-triazole (D26) had broad spectrum fungicidal and herbicidal activity. The IC50values against duckweedwere 20.5 +/- 9.0, 14.2 +/- 6.7, 24.0 +/- 11.0, 8.7 +/- 3.5, and 8.0 +/- 3.1 mu M forD17,D20,D22, andD26and the positive controldifenoconazole, respectively. The EC50values were 7.31 +/- 0.67, 9.74 +/- 0.83, 17.32 +/- 1.23, 11.96 +/- 0.98, and 8.93 +/- 0.91 mg/L forD17,D20,D22, andD26and the positive control difenoconazole against the plant pathogenR. solani, respectively. Germinationexperiments withArabidopsisseeds indicated that the target of these dioxolane ring compounds in plants is brassinosteroidbiosynthesis. Molecular simulation docking results of compoundD26and difenoconazole with fungal CYP51 P450 confirmed thatthey both inhibit this enzyme involved in ergosterol biosynthesis. The structure-activity relationships (SAR) are discussed bysubstituent effect, molecular docking, and density functional theory analysis, which provided useful information for designing moreactive compounds