(S)-Zearalenone, a natural product isolated from the fungus Gibberella zeae, exhibits useful biological activity, including antibiotic properties. In a total synthesis of (S)-zearalenone, an intramolecular Stille coupling process was employed as the penultimate procedure.3 The resulting coupling product was then treated with HCl to cleave the OR groups, thereby converting them into OH groups (as seen in Section 13.6), giving (S)-zearalenone. Draw the structure of (S)-zearalenone: