Retrosynthetic Analysis of Longifolene

The first successful synthesis of longifolene was described in detail by E. J. Corey and co-workers in 1964. Scheme 13.19 presents a retrosynthetic analysis corresponding to this route. A key disconnection is made on going from I => II. This transformation simplifies the tricyclic skeleton to a bicyclic one. For this disconnection to correspond to a reasonable synthetic step, the functionality in the intermediate to be cyclized must engender mutual reactivity between C-7 and C-10. This is achieved in diketone II, because an enolate generated by deprotonation at C-10 can undergo an intramolecular Michael addition to C-... 

The logic centered approach leads to a restricted set of structures that may be converted in a single step to the target. Each new structure can. in turn, be converted to a new structure. The purpose of the retrosynthetic analysis is to generate synthetic intermediates (the synthesis tree) that terminate with a number of starting materials.Corey et al. outlined this approach in 1964 in his synthesis of longifolene (73), which is shown in Scheme 10.4.- 2 This synthesis used the 33 ieland-Miescher ketone (72) as the starting material. - Analyses... 

---