Concise Synthesis of (3Z)-Dodecen-12-olide, Pheromone Component of the Emerald Ash Borer

Abstract

Emerald ash borer (EAB), Agrilus planipennis Fairmaire, is an invasive insect that has killed millions of ash trees in Canada and the USA. (3Z)-Dodecen-12-olide is a known female-produced pheromone of this insect, and a concise, three-step synthesis of a 2:1 blend of (3Z)-dodecen-12-olide and (3E)-dodecen-12-olide starting from commercially available (2-carboxyethyl)triphenylphosphonium bromide and 10-bromo-1-decene is described. The key steps in this synthesis are a lithium-salt-free Wittig reaction and an intramolecular S_N2 esterification. Both of these macrocyclic lactones are behaviorally active toward EAB, and the 2:1 blend whose synthesis is described here has the potential to be a detection agent, mating disruptor, or mass trapping agent, which could be used in the control of EAB.

GRAPHICAL ABSTRACT

Keywords:

• (3E)-Dodecen-12-olide
• (3Z)-dodecen-12-olide
• emerald ash borer
• mating disruption
• pheromone

ACKNOWLEDGMENT

We thank Matt Brophy for technical assistance.

Notes

^a See Experimental section for in situ formation of 25a and subsequent Wittig reaction in 1,2-DME.

^b EtOH was removed in vacuo after formation of 25a was complete, and THF was added as the solvent for the subsequent Wittig reaction.