In a study aiming to determine the structural elements essential to the antifungalactivity of kakuol, we synthesized a series of 2‐hydroxy‐4,5‐methylenedioxyaryl ketones, and we assayed their in vitro antifungalactivity. The most sensitive target organisms to the action of these class of compounds were Phytophthora infestans, Phytium ultimum, Cercospora beticola, Cladosporium cucumerinum, and Rhizoctonia