Analogs of phytoalexins. Synthesis of some 3-phenylcoumarins and their fungicidal activity

Little is known about the relationship between fungicidal activity of isoflavonoid phytoalexins and their physicochemical properties, in particular partition properties. As a first part of an investigation on the influence of partition coefficients on the fungicidal activity of analogues of isoflavonoid phytoalexins, a series of 3-phenylcoumarins, including ethers and side-chain derivatives of high lipophilicity, were synthesized and tested in vitro and in vivo for antifungal activity. The results seem to indicate that an increase of lipophilicity has a negative effect and a free OH is indispensable for activity.