Pheromones retrosynthetic analysis

As an example of this strategy, let s consider the synthesis of 2-methyl-6-methylene-7-octen-4-ol, an insect pheromone. (As described in the Focus On box on pages 1025-1026, pheromones are compounds used by animals, especially insects, for communication.) The synthesis of this alcohol, a component of the sex attractant of the male bark beetle, has been described in the literature. Retrosynthetic analysis, similar to that described earlier, suggested the use of a Grignard reaction to prepare this alcohol ... 

This section presents several syntheses to further illustrate retrosynthetic analysis. First, let s consider the synthesis of dispalure, the sex pheromone of the gypsy moth, a serious despoiler of forests. 

Disparlure, the sex pheromone of the female gypsy moth, is synthesized by a stepwise reaction sequence that uses an epoxidation reaction as the final step. Retrosynthetic analysis of disparlure illustrates three key operations ... 

The advantages of Robinson s concept was confirmed in numerous total syntheses of alkaloids. One of the most illustrative examples is served by Stevens synthesis of the tricyclic compound coccinelline 45 (Scheme 3.10), the pheromone of the ladybug (ladybird). As was acknowledged in Stevens review article, in less time than it took to write this paragraph, we had developed on paper an attractive approach that relies on one of the oldest reactions known in alkaloid synthesis, namely the classical Robinson-Schopf condensation . This approach involved the retrosynthetic transformation of 45 into the ketopiper-idine derivative 46, which is amenable to disconnection in accordance with the same logic as used by Robinson in the analysis of tropinone. 

---