Synthesis and biological evaluation of furopyrimidine N,O-nucleosides

A series of modified N,O-nucleosides, characterized by the presence of a furopyrimidine moiety, has been synthesized by exploiting a Sonogashira cross coupling reaction of 1-isoxazolidinyl-5-iodouracil with alkynes, followed by treatment with CuI in refluxing TEA/MeOH mixture. The obtained compounds were screened against both RNA and DNA viruses. None of the compounds were endowed with antiviral activity at subtoxic concentrations. However, some of them were able to inhibit proliferation of MRC-5, Vero, BS-C-1 cells by 50% (CC50) at concentrations ranging from 0.7 to 62.5 mM.