Synthesis of the sex pheromone of the obscure mealybug, the first example of a new class of monoterpenoids

Abstract A diastereoselective synthesis of (1 R ∗ ,2 R ∗ ,3 S ∗ )-1-acetoxymethyl-2,3,4,4-tetramethylcyclopentane, the sex pheromone of the obscure mealybug Pseudococcus viburni , is described. Key steps included the polyphosphoric acid-catalyzed cyclization of isobutyl methacrylate to form the core five-membered ring, and diastereoselective quenching of an enolate intermediate to give the thermodynamically less favored cis orientation of vicinal methyl groups in a cyclopentanone intermediate.