Eysarcoris lewisi

Wallmeyer. It sometimes happens that the same compound is produced by different organisms in different parts of the world. 

4 Clarification of the relationship between absolute configuration and pheromone activity—ex o -brevicomin 

D-(-)-Tartaric acid, the unnatural enantiomer, was converted to the known ditosylate A. Two-carbon elongation of A with sodium cyanide was problematic. When the required amount (2 moles) of sodium cyanide was added in one portion to a DMSO solution of A, crystalline (2 ,4 )-2,4-hexadienedinitrile 

The bioassay of (l/ ,55,7R)-(+)-exo-brevicomin (76) and its (-)-enantiomer 16 ) was carried out by Professor David L. Wood and coworkers at the University of California, Berkeley. When I visited his laboratory in June 1974, I was deeply impressed by the fact that only (+)-76 was pheromonally active to attract the beetles. A large-scale field test also indicated that (+)-76 was the bioactive isomer, while (—)-76 was neither active nor inhibitory.32 Thus, only a single enantiomer of the pheromone was found to 

The cage-like intramolecular acetal structures of 77 and 78 attracted my attention, and we synthesized both ( )-77 and ( )-78, the former of which showed the spectral data identical to those of the natural lineatin.33,34 Photocycloaddition of vinyl acetate to 3-methyl-2-cyclopentenone (A) gave B, from which were prepared two isomeric ketones C and D. These were separable by chromatography, and their structures could be determined by -NMR analysis. The ketone ( )-C was further converted to ( )-77, while ( )-D 

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A simple example of the examination of a proposed structure through synthesis is provided in this section. In 2005, Takita12 proposed the structure of the male-produced aggregation pheromone of the stink bug Eysarcoris lewisi as the sesquisabinene alcohol, ( )-2-methyl-6-(4 -methylenebicyclo[3.1.0]hexyl)hept-2-en-l-ol (8) (Scheme 1). Mori13 synthesized (61 )-8 and (6S)-8 from the enantiomers of citronellal (10). The key steps were the intramolecular addition of an ct-keto carbene to the alkene bond (11—>12) and ( )-selective olefination of 13 to give 14. The 1H- and 13C-NMR spectra of 8 around the trisubstituted double bond at C-2 were different from those of the natural pheromone. 

Scheme 2 Synthesis of the male-produced aggregation pheromone of the stink bug Eysarcoris lewisi. Reagents ...

Figure 4.11 Elucidation of the correct gross structure of the pheromone of Eysarcoris lewisi by synthesis...

Preparation of bicyclic alcohol (6/ ,1 S,4 S,5 / )-51, which was converted to the pheromone of Eysarcoris lewisi. 

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