Two-step synthesis of (±)-stigmolone, the pheromone of Stigmatella aurantiaca

Racemic stigmolone (8-hydroxy-2,5,8-trimethyl-4-nonanone), the pheromone of myxobacterium Stigmatella aurantiaca, was synthesised in 67% overall yield, using titanium-mediated hydroxycyclopropanation of 2-methyl-5-hexen-2-ol with ethyl isovalerate followed by the base-induced ring opening of the resulting 2-(3-hydroxy-3-methylbutyl)-1-isobutyl-1-cyclopropanol.