SYNTHESIS AND BIOLOGICAL EVALUATION OF STRIGOL ANALOGS MODIFIED IN THE ENOL ETHER PART

Several analogues of strigol, which is a germination stimulant for see ds of the parasitic weeds Striga and Orobanche, have been prepared. St ructural modifications are introduced in the vinyl ether part and incl ude: i, analogues containing an endocyclic vinyl ether double bond, us ing tetronic acids as precursors; ii, geometrical isomerization of the vinyl ether double bond; and iii, analogues containing a methyl subst ituent on the vinyl ether double bond. During coupling reactions to gi ve compounds belonging to the last-mentioned class, undesired C-alkyla tion occurs, which can be minimized by choosing the appropriate reacti on conditions. Bioassays reveal that the analogues prepared exhibit co nsiderable activity in the stimulation of seed germination of Striga h ermonthica and Orobanche crenata.