A series of hitherto unknown acyclic 5,5-difluoro-5-phosphono-pent-2-en-1-yl-pyrimidines (9a, b, 13a, b), -purines (16a, b) and -(1,2,4)-triazolo-3-carboxamide (19) were successfully synthesized from (E)-1-bromo-5-diethoxyphosphoryl-5,5-difluoro-pent-2-ene in a stereoselective manner. All the synthetized compounds were assayed for antiviral activity against various viruses, but were found to be neither active nor toxic.