Synthesis and biological evaluation of acyclic nucleotide analogues with a furo[2,3- <i>d</i> ]pyrimidin-2(3 <i>H</i> )-one base

As a part of a broader structure–activity relationship (SAR) study of bicyclic nucleoside analogues (BCNAs) [anti-varicella-zoster virus (anti-VZV) and anti-human cytomegalovirus (anti-HCMV) agents], a novel series of 2-(phosphonomethoxy)ethyl (PME) substituted furo[2,3-d]pyrimidin-2(3H)-ones was synthesized. The target acyclic nucleotide analogues were prepared by Sonogashira coupling of protected 5-iodo-1-[2-(phosphonomethoxy)ethyl]uracil with various 1-alkynes, followed by in situ Cu(I)-promoted intramolecular cyclization and standard removal of the isopropyl ester groups. None of the prepared PME analogues were active at subtoxic concentrations against VZV thymidine kinase competent (TK + ), VZV thymidine kinase deficient (TK – ), HCMV, or any other viruses tested.