Pheromone of the fall webworm moth

In order to determine the absolute configuration of C, we synthesized (3Z,6Z,95,10/O-9,10-epoxy-3,6-henicosadiene (91) and its enantiomer 91 employing the Sharpless asymmetric epoxidation as the key step.55,56 Asymmetric epoxidation of D afforded (2/ ,35)-E of 80.6% ee. This was converted to the corresponding 3,5-dinitrobenzoate F and recrystallized to give enantiomerically pure F. Further synthetic transformation converted F to (95,10/0-91. Bioassay of (95,10/0-91 proved it to be pheromonally active, while the enantiomer (9/ ,105)-91 was inactive. A blend of A, B and C (= 91), however, was pheromonally inactive when tested against H. cunea. Two additional components 92 and 93 were necessary for the pheromone action. In 1987 Dr. H. Arn in Switzerland asked me to synthesize these two compounds. We did this, and in 1989 Toth, Arn and their coworkers published the identification of 92 and 93. 

93 were also synthesized by starting from B. Bioassay revealed (9S,10/f )-92 and (9S,10/f )-93 to be the bioactive enantiomers. 

The synthetic pheromone lure containing A, B, 91, 92 and 93 was bioactive in both Europe and Japan. Subsequently, in 1993 Senda et al. found that a blend of 91, B and 92 could attract H. cunea, and this blend was developed as a commercial lure for monitoring the population of H. cunea. 

For the synthesis of (9S,10/f)-92, its side-chain part H was prepared first. It was then coupled with E to give I. Subsequently, I was converted to (9.S ,10E)-92. Its overall yield was 8.6% (12 steps). This new synthesis will be useful in securing practical amounts of 91 and 92. 

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