(Chemical Equation Presented) Highly stereoselective dithiocarbonylation of propargylic mesylates with thiols and carbon monoxide has been developed by the use of tetrakis(triphenylphosphine)palladium(0) as the catalyst at 90 °C in THF. The reaction affords the corresponding dithioesters in good to excellent yields. For some secondary and tertiary propargylic alcohols with a terminal or internal triple bond, the reaction stereoselectively produces E-dithioesters as products. The dithiocarbonylation is believed to proceed via allenylpalladium and allenyl ester intermediates, and the high st...