Pheromone Synthesis, CCVIII: Synthesis of (1S,3S,7R)-3-Methyl-α-himachalene, the Sex Pheromone of the Sandfly Lutzomyia longipalpis from Jacobina, Brazil

Abstract

(1S,3S,7R)-3-Methyl-α-himachalene, the sex pheromone of the male sandfly (Lutzomyia longipalpis) from Jacobina, Brazil, was synthesized enantioselectively by employing Evan's or Oppolzer's asymmetric methylation and intramolecular Diels-Alder reaction as the two key steps. The absolute configuration of the product was unambiguously established by X-ray analysis of a compound related to one of the synthetic intermediates. The ring junction of this sandfly pheromone possesses the absolute configuration opposite to that of the known (1R,7R)-α-himachalene of plant origin.