Iridomyrmecin derivatives

Transannulation of the mesylate (33), derived from 4,8-dimethylcycloocta-4-en-l-ol, using sodium carbonate in aqueous dioxane has provided the bicyclo[3.3.0]octanol (34), a central precursor to the monoterpene iridomyrmecin (35 equation 13). In studies of the biomimetic synthesis of the natural tri-quinanes capnellene (37 equation 14) and pentalenene (40 equation IS) Pattenden et al. have shown that both molecules can be produced from appropriate cycloocta-l,S-diene precursors, i.e. (36) and (39) [or indeed their corresponding positional isomers (38) and (41), respectively] by treatment with boron trifluoride. Mehta et al. have described an alternative transannulation approach to the triquinane unit found in pentalenene, i.e. (42) - (43 equation 16), and also to the ring system (44 equation 17) found... 

It should also be mentioned that substantial synthetic effort has been directed towards the formation of monoterpene lactone derivatives such as boschnialactone (217), iridomyrmecin (218), and isoiridomyrmecin (205)... 

---