Diazotization of (I) with isoamyl nitrite in the presence of dipropyl disulfide afforded sulfide (III) through the intermediate diazonium salt (II). Further substitution of the chloro atom of (III) for ammonia provided 2-(propylthio)adenosine (IV). The 5'-hydroxyl group of (IV) was then phosphorylated by reaction with phosphoryl chloride in cold triethyl phosphate followed by aqueous work-up. The resulting 5'-monophosphate (V) was treated with carbonyl diimidazole and tri-n-butylamine to produce the phosphoryl imidazole intermediate (VI), which was finally condensed with dichloromethylenebis(phosphonic acid) (X). The target compound was isolated as the tetrasodium salt upon treatment with NaI in methanol-acetone.