Treatment of 3-phenyliodonio-1, 2, 4-trioxo-1, 2, 3, 4-tetrahydronaphthalenides with terminal acetylenes in the presence of a bis (triphenylphosphine) palladium chloride-cuprous iodide catalyst or cuprous oxide in N-methylpiperidine or pyridine, respectively, furnished the corresponding 2-substituted naphtho [2, 3-b] furan-4, 9-diones in moderate to good yields. The utility of this method was demonstrated in the synthesis of a cytotoxic natural product, ...