New angular oxazole-fused coumarin derivatives: synthesis and biological activities

Twelve angular oxazole-fused coumarin derivatives were designed, synthesised and characterised by ¹H NMR, ¹³C NMR and HRMS. The structure of compound 4a was further confirmed by X-ray single-crystal diffraction. The bioassay experiment results indicated that compounds 4f and 4l have high antifungal activity on the mycelium growth of 4 plant disease fungi. Especially, compound 4l has a stronger antifungal activity compare to the commercial fungicide, Carbendazim. The herbicidal activity experiment showed that 4a and 4b can significantly inhibit the taproot and caulis development of Chenopodium album seedling and have better activities than the commercial herbicide, Acetochlor.