(2,3,4,4-Tetramethylcyclopentyl)Methyl Acetate, a Sex Pheromone from the Obscure Mealybug: First Example of a New Structural Class of Monoterpenes

The sex pheromone of the obscure mealybug, Pseudococcus viburni , consists of (1 R *,2 R *,3 S *)-(2,3,4,4-tetramethylcyclopentyl)methyl acetate, the first example of a new monoterpenoid structural motif in which the two isoprene units forming the carbon skeleton are joined by 2′–2 and 3′–4 connections rather than the usual 1′–4, head-to-tail connections. This highly irregular terpenoid structure, and the irregular terpenoid structures of related mealybug species, suggest that these insects may have unique terpenoid biosynthetic pathways.