Synthesis of Spirocyclic Enones by Rhodium-Catalyzed Dearomatizing Oxidative Annulation of 2-Alkenylphenols with Alkynes and Enynes

The dearomatizing oxidative annulation of 2-alkenylphenols with alkynes and enynes proceeds with high yields and regioselectivities under Rh-III catalysis. These reactions are successful using Cu(OAc)(2) or air as the stoichiometric oxidant, and provide spirocyclic enones, the basic ring system of which appears in several natural products. Application of this process to the preparation of a highly functionalized tetracycle is also demonstrated.