Alkylation of adenosine-2-thione (I) with iodopropane produced the propylthioether (II). Subsequent treatment with phosphoryl chloride in triethyl phosphate, followed by aqueous work-up afforded (propylthio)adenylic acid (III). Then, after activation with carbonyldiimidazole, the condensation of (III) with difluoromethylenebisphosphonic acid (IV) generated the target anhydride.