The acid-catalyzed 4 p-electrocyclic ring closure of a divinyl carbonyl substrate (ie, the Nazarov cyclization) is a reaction of substantial synthetic utility for pentannulation.[1] Because of its growing popularity in the arena of complex molecule synthesis, the reaction has evolved to include several variants.[2, 3] We became interested in the Nazarov reaction as a means to access the A and B rings of the natural product tetrapetalone A (1, Scheme ...