A diastereoselective synthesis of (1SR,3SR,7RS)-3-methyl-α-himachalene, the sex pheromone of the sandfly, Lutzomyia longipalpis (Diptera: Psychodidae)

The sandfly, Lutzomyia longipalpis, vectors the causative agent of visceral leishmaniasis in the New World. The male-produced pheromone, (1S,3S,7R)-3-methyl-α-himachalene provides an opportunity for pest managing this pest problem by influencing the behaviour of the biting female. Previous syntheses of the pheromone have all focused on a late stage Diels-Alder cyclisation to generate the bicyclic cis-himachalene skeleton. By adopting a new retrosynthetic analysis that depends on an early stage Diels-Alder cyclisation, the number of steps has been reduced to ten, of which five are catalytic and so provides access to quantities suitable for field-scale experiments.