Synthetic studies of zoanthamine alkaloids. Stereoselective synthesis of the ABC ring system of norzoanthamine by an intramolecular Diels–Alder reaction

Stereoselective synthesis of the ABC ring system of norzoanthamine having five asymmetric centers including two quaternary carbon atoms has been successfully accomplished by an intramolecular Diels–Alder reaction. A key intermediate for the Diels–Alder reaction was efficiently and stereoselectively synthesized by a tandem conjugate addition–aldol strategy and subsequent photosensitized oxidation of a furan derivative.