Studies Toward the Enantiospecific Total Synthesis of Rhodexin A

Studies toward the enantiospecific total synthesis of rhodexin A via a very hindered inverse electron demand Diels–Alder reaction are described. The C8-diastereomer of the fully elaborated tetracyclic core of rhodexin A, 23, was prepared in good yield and excellent selectivity using as the key step the stepwise Diels–Alder reaction of the very hindered dienone 3 and the silyl enol ether 4 catalyzed by the very strong Lewis acid, dimethylaluminum triflimide.