Mechanisticstudies of tandem regioselective decarboxylation, prenyltransfer, and aromatization reactions of prenyl dioxinone diketo-carboxylates to provide 3-prenyl-resorcylate derivatives are described. Studies of the effects of concentration and the base employed as well as the results of cross-over experiments were all found to be consistent with the reaction proceeding largely via an intermolecular