Acyclic nucleoside phosphonates containing the amide bond

To study the influence of a linker rigidity and donor-acceptor properties, the P-CH2-O-CHR- fragment in acyclic nucleoside phosphonates (e.g., acyclovir, tenofovir) was replaced by the P-CH2-HN-C(O)- residue. The respective phosphonates were synthesized in good yields by coupling the straight chain of omega-aminophosphonates and nucleobase-derived acetic acids with EDC. Based on the H-1 and C-13 NMR data, the unrestricted rotation within the methylene and 1,2-ethylidene linkers in phosphonates from series a and b was confirmed. For phosphonates containing 1,3-propylidene (series c) fragments, antiperiplanar disposition of the bulky O,O-diethylphosphonate and substituted amidomethyl groups was established. The synthesized ANPs P-X-HNC(O)-CH2B (X = CH2, CH2CH2, CH2CH2CH2, CH2OCH2CH2) appeared inactive in antiviral assays against a wide variety of DNA and RNA viruses at concentrations up to 100 mu M while marginal antiproliferative activity (L1210 cells, IC50 = 89 +/- 16 mu M and HeLa cells, IC50 = 194 +/- 19 mu M) was noticed for the analog derived from (5-fluorouracyl-1-yl)acetic acid and O,O-diethyl (2-aminoethoxy)methylphosphonate.