Short and simple syntheses of 4-oxo-(E)-2-hexenal and homologs: pheromone components and defensive compounds of Hemiptera.

One-step syntheses of 4-oxo-(E)-2-hexenal and 4-oxo-(E)-2-octenal from commercially available 2-ethyl- and 2-butylfuran are described. A two-step synthesis of the homolog 4-oxo-(E)-2-decenal from furan is also reported. These compounds are common components of true bug defensive secretions, and recently have been identified as pheromone components for several species. The simple syntheses reported here will make these compounds readily available for further research.