To discover new potential fungicides with innovative scaffolds, two novel quinoline derivatives incorporating a camphor scaffold were designed, synthesized, and evaluated for their inhibitory activity against three plant pathogenic fungi and oomycetes. Initial antifungal assays indicated that these compounds exhibited moderate to good antifungal activity against the tested plant pathogens. Notably, compound 3a showed outstanding in vitro antifungal efficacy against Sclerotinia sclerotiorum, significantly surpassing the performance of chlorothalonil.

Further in vivo activity testing revealed that compound 3a provided excellent protective effects on pepper plants infected with Phytophthora capsici at a concentration of 1000 mg/L, demonstrating efficacy comparable to that of chlorothalonil. Preliminary mechanistic studies suggested that compound 3a could disrupt the surface morphology of S. sclerotiorum. The combined results from bioassays and mechanistic analysis indicate that this class of quinoline derivatives holds promise as a potential new fungicide for further development.