A Simple and Short Synthesis of Z-6-Heneicosen-11-One and Z-1,6-Heneicosen-11-One,The Sex Pheromones of Douglas-Fir Tussock Moth

Z-6-Heneicosen-11-one (1) and Z-1,6-Heneicosen-11-one (2) are the sex pheromones of the Douglas-Fir Tussock moth, ‘Orgyia Pseudo Sugata’, isolated^1,2 in 1975 and 1978 respectively. In contrast with other lepidopterous pheromones, which are unsaturated C₁₂-C₁₄ primary alcohols or acetates, these were found to be C₂₁ ketones. The Douglas-Fir Tussock moth is a severe defoliator of the Fir forest; consequently, considerable interest attends the synthesis of these two pheromones. A number of syntheses of these two pheromones have been reported3 amongst which is one of our synthesis using N,N-dimethyl acetone 4 hydrazone as key intermediate.