Abstract–A series of hydrolytically stable O2-and N3-(2-phosphonomethoxy)-ethyl (PME) derivatives of 6-phenyl, pyridin-2,-3 and-4-yl-5-azacytosines was prepared by their alkylation with diisopropyl (2-chloroethoxy) methylphosphonate followed by the deprotection. No antitumor or antiviral activity was found except for 6-(pyridin-4-yl)-1, 3, 5- triazine-2, 4-diamine (13d) which exhibited slight activity against feline herpesvirus in ...