6-chloropyrimidines with diethyl [(2-aminoethoxy)methyl]phosphonate allows for a ready access to acyclic nucleoside phosphonates. A series of 5-substituted pyrimidines bearing a phosphonate side chain at position 6 were synthesized and tested against herpes simplex viruses (HSV-1 and HSV-2) and human immunodeficiency virus (HIV-1). Some compounds showed weak antiviral activity against HSV-1.