Synthesis of the Sex Pheromone of the Oleander Scale ( Aspidiotus nerii).

A total synthesis of the oleander scale [Aspidiotus nerii (Bouche)] sex pheromone, the unique sesquiterpenoid containing a cyclobutane moiety of this class of compounds, has been developed. In order to implement this sex pheromone as a new environmentally friendly tool to manage this pest, a more cost-effective, multigram synthesis was required. This new synthetic route, having a Blaise reaction, iron-catalyzed carbon- carbon coupling, and [2 + 2] photocycloaddition reactions as key steps, provides a general access to 4-alkyl lactones as well as a robust access to the target sex pheromone. Starting from readily available compounds as 3-hydroxypropanenitrile, ethyl bromoacetate, and 2-acetyl butyrolactone, the synthetic sequence afforded the A. nerii sex pheromone with minimum intermediate purification and good overall yield in nine linear steps.