Synthesis of a Highly Functionalized Triquinane: Studies Towards a Total Synthesis of Subergorgic Acid and Its Analogues

Reaction of enone (11) with the bifunctional Grignard reagent (7) in the presence of copper(I) bromide – dimethyl sulfide, followed by intramolecular alkylation of the resultant chloroketone (15) gave the tricyclic ketone (12). The tricyclic ketone (12) was transformed into the angular triquinane dienedione (9) by means of an 8-step sequence.