Synthesis and Biological Activity of Waltherione F‐derived Diamide Derivatives Containing 4‐Quinolone Group

The exploitation of new fungicides and the discovery of action targets are effective ways to solve the problem of resistance, and structural optimization of natural products has become an resultful method to discover lead compounds. In this work, in conjunction with the structures of the fungicidal lead compounds h‐I‐9, X‐I‐3, and X‐II‐5 found in our previous project, waltherione F‐derived diamide compounds were synthesized and characterized by 1H NMR, 13C NMR, and HRMS. The biological assays suggested that the target compounds exhibited weak to good fungicidal activity against the tested pathogens, while most of the target compounds displayed high cellular cytotoxicity against Hela cells. The investigation of accidentally discovered fluorescence characteristics revealed that the compound I‐1 exhibited the most vigorous fluorescence intensity at 350 nm, which was significantly higher than that of I‐3 at 225 nm and was further elucidated by density functional theory (DFT) calculations. Overall, the above results would provide theoretical guidance for the design of active target molecules and the development of fluorescent probes.