The reaction of propargylic alcohols with diaryl disulfides and carbon monoxide in the presence of tetrakis (triphenylphosphine) palladium leads to a novel thiolative lactonization to afford β-(arylthio)-α, β-unsaturated lactones in moderate to good yields. Similar conditions can be employed with homopropargylic alcohols, giving the corresponding δ-lactones with a β-arylthio group successfully. The reaction using diaryl diselenides in lieu of diaryl ...