With 21 in hand, we turned our attention to the final C-C bond formation of the synthesis. By subjecting vinyl iodide 21 to standard radical cyclization conditions, we were able to close the tetrahydrofuran ring in good yield. As expected, no other cyclization products were observed, and the only other product detected arose from protodehalogenation. Finally, we were able to close the lactone by treatment with aluminum methoxide as a mild Lewis acid in refluxing xylenes. These conditions were necessary because the hydroxyester (not shown) proved to be sensitive to both acid and base. Despite this, we were able to accomplish late-stage lactone formation to afford nimbolide (1) in high yield.