Approaches toward the Total Synthesis of the Nine-Membered Thio-Lactone Core of Griseoviridin

Three different approaches toward the synthesis of the macrocyclic thiolactone core of griseoviridin have been studied. Intramolecular palladium-catalyzed thiol coupling and esterification (carboxylate activation) have led to the formation of unexpected rearranged products. An intermolecular palladium-catalyzed thiol/vinyl iodide coupling followed by an esterification (alcohol activation) ultimately led to the nine-membered core of griseoviridin.