Synthesis of a complex substance such as copaene can be approached in many different We envisioned the synthesis of a properly substituted diene 4, which on photolysis could yield the desired [3. ll] bicyclohexane system B. If R were a suitably chosen group (CH, CO-, for example) then addition of the third ring would seem to present no serious problems, and final alteration of such a tricyclic compound to the natural product should be ...