Strigol, a natural product isolated from root exudates of cotton, was found to be an extremely potent seed germination stimulant for the parasitic plant, witchweed. Witchweed seeds can remain dormant in the soil for several years until favorable conditions prevail including exposure to some type of chemical germination stimulant. Several strigol analogues, 3-methyl-4-(2-oxo-3,3a,6,6a-tetrahydro-2H-cyclopenta[b]furan-3-ylidenemethoxy)-but-2-en-4-olide(21), 4-(2-oxo-3,3a,6,6a-tetrahydro-2H-cyclopenta[b]furan-3-ylidenemethoxy)but-2-en-4-oilde(22), 3-methyl-4-(2-oxotetrahydrofuran-3-ylidenemethoxy)-but-2-en-4-olide(23), and 4-(2-oxotetrahydrofuran-3-ylidenemethoxy)-but-2-en-4-olide(24), were synthesized.
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