The Fraser-Reid retrosynthetic analysis of - -silphiperfolene

The disconnection of enantiopure carbocycles is never an easy task, but this is especially so when the target molecule possesses multiple ring systems comprised entirely of carbon and hydrogen atoms linked together via a bonds. When confronted with such structures it is often advisable (or even necessary) to retrosynthetically functionalise one or more of the ring systems present to permit a simplifying disconnection to be made. Once a hydroxyl, an amine, a carbonyl, or some other multiply bonded unit is positioned within a ring, this usually primes adjacent or nearby bonds for immediate disconnection, or for further functionalisation followed by disconnection. 

The presence of a tetrasubstituted C=C bond in the A-ring of (—)-silphiperfolene provides a logical starting point from where to commence retrosynthetic disassembly. It was Fraser-Reid s view that the option of further functionalisation followed by disconnection was the more 

It will soon be appreciated that rupture of bonds b, c and e offers no real tactical advantages. For example, radical cleavage of bond b creates an eight-membered unsaturated carbocycle 8 that is even more 

---