Intramolecular [2 + 2]-photocycloaddition/thermal fragmentation approach toward 5-8-5 ring systems.
[reaction: see text]. An intramolecular [2 + 2]-photocycloaddition is used to provide a photoadduct, which upon fragmentation, lactone cleavage, and subsequent Cope rearrangement provides a dicyclopenta[a,d]cyclooctene ring system with substituents in place (e.g., C3 and C11) to access several 5-8-5 diterpene and sesterterpene natural products.
Lo
P C
PC
Eugene F. Merkert Chemistry Center, Boston College, Chestnut Hill, Massachusetts 02467-3860, USA.
Snapper
M L
ML