Spectacular Ring Construction Strategies

Using the [4.4.0] ring system as an illustrative example, certain general structural motifs are pertinent. These are codified with nicknames signifying familiar shapes and are represented by 

For each case, the chemical transformation is given followed by a simplified graphical equation of the formal transformation to form the relevant ring system using the notation presented at the beginning of this chapter. References for the plans are given in the accompanying CD-ROM. 

Zhai (2005) plan for absinthin photo-rearrangement in step 1 Diels-Alder reaction in step 5. 

Trost (2004) plan for amphidinolide P step 15 (macrocyclization-rearrangement) 

Note that the lactone ring in the snbstrate is a sacrihcial ring in this transformation. Corey (1999) plan for aspidophytine step 12. 

---