Design, synthesis and structure-activity relationship of novel coumarin derivatives.

Background: The lead coumarin derivative (E)-methyl 3-methoxy-2-[2-(4-methylcoumarin-7-yloxymethyl)phenyl]acrylate was discovered by using an intermediate derivatisation method. To discover new coumarin derivatives with improved activity, a series of substituted coumarins were synthesised and bioassayed.

Results: The compounds were identified by ¹H NMR, IR, MS and elemental analysis. Bioassays demonstrated that some of the title compounds exhibited excellent fungicidal activity against cucumber downy mildew at 25 mg L⁻¹. The relationship between structure and fungicidal activity is reported.

Conclusion: The present work demonstrates that coumarin derivatives containing methoxyacrylate moieties can be used as possible lead compounds for developing novel fungicides.