Synthesis and Nematocidal Activity of Hydroxystilbenes

Various (E)-hydroxystilbenes were synthesized from (E)/(Z) mixtures of methoxystilbenes through a new (Z)-(E) isomerization method followed dy demethylation. The nematocidal activity appears when methoxystilbenes are demethylated to hydroxystilbenes. For this activity, a hydroxy group at the C-2 or C-3 position is necessary. Thus, 2-hydroxy-, 3-hydroxy-, 2, 6-dihydroxy-, 3, 4-dihydroxy-, 3, 5-dihydroxy-, 2, 2'-dihydroxy-, 3, 3'-dihydroxy-, 3, 4'-dihydroxy-, 2-hydroxy-4-methoxy-, 5-hydroxy-2-methoxy-, 2-hydroxy-6-methoxy-, 6-allyloxy-2-hydroxy-, 3-hydroxy-5-methoxy-, and 5-allyloxy-3-hydroxystilbenes showed rather potent nematocidal activity. The activity of 5-allyloxy-3-hydroxystilbene was the strongest [minimal lethal concentration (MLC)=30 μM]. The activities of the (E) and (Z) isomers were comparable. The activities were also retained, though they were weaker, in the dihydro derivatives, hydroxybibenzyls.