A new synthesis of (Z,Z)-11,11-dimethoxy-6,9-heneicosadiene and 2-((Z,Z)-1,4-decadienyl)-2-(n)decyl-1,3-dioxolane, precursors of (Z,Z)-6,9-heneicosadien-11-one, a pheromone component of the whitemarked tussock moth, Orgyia leucostigma (JE Smith) (Lepidoptera: Erebidae)

The straightforward synthesis of two long-chain diene ketals, (Z,Z)-11,11-dimethoxy-6,9-heneicosadiene and 2-(n)decyl-2-((Z,Z)-1,4-decadienyl)-1,3-dioxolane, is described. These two ketals are synthetic propheromones, or pheromone precursors, of the whitemarked tussock moth (WMTM, Orgyia leucostigma (J.E. Smith) (Lepidoptera: Erebidae)), whose unstable female-produced sex pheromone component, (Z,Z)-6,9-heneicosadien-11-one, lasts only 1-2 days in traps in the field. The two propheromones were synthesized by terminal alkyne/propargylic bromide couplings, facilitated by cesium carbonate, which assembled the 21-carbon chains with skipped diynes. Semi-reduction of the diynes gave the requisite dienes. These two diene ketals were then formulated into lures, which converted them in situ into the attractive (Z,Z)-6,9-heneicosadien-11-one. The performance of these lures is briefly described.