Concise Syntheses of ent-Aquilanol A and Aquilanol B via Retro-cycloisomerization of (-)-Caryophyllene Oxide. Access to Medium-sized Oxygenated Carbocyclic Scaffolds

The first concise synthesis of naturally occurring aquilanols A and B, two unprecedented 7/10 bicyclic sesquiterpenoids, is present-ed. Key features of the synthesis are a retrocycloisomerization event on (-)-caryophyllene oxide to form the eleven-membered car-bocyclic frame and an intramolecular epoxide opening to construct the bicyclic skeleton. The latter provides evidence to plausible biosynthesis of natural compounds, rendering our synthesis biomimetic. Our plan provides selectively access to other medium-sized carbocyclic oxygenated compounds, thus enhancing the structural diversity of final products.