A series of linear furanocoumarins with different substituents have been designed and synthesized. Their structures were confirmed by 1H-NMR spectroscopy, high resolution mass spectra (EI-MS), IR, and X-ray single-crystal diffraction. All of the target compounds were evaluated in vitro for their antifungal activity against Rhizoctorzia solani, Botrytis cinerea, Alternaria solani, Gibberella zeae, Cucumber anthrax, and Alternaria leaf spot at 100 μg/mL, and some of the designed compounds exhibited potential antifungal activities. Compound 3a (67.9%) exhibited higher activity than the control Osthole (66.1%) against Botrytis cinerea. Furthermore, compound 4b (62.4%) represented equivalent antifungal activity as Osthole (69.5%) against Rhizoctonia solani. The structure-activity relationship (SAR) study demonstrates that linear furanocoumarin moiety has an important effect on the antifungal activity, promoting the idea of the coumarin ring as a framework that might be exploited in the future.
