Abstract: | The synthesis of uridine-5′-diphosphate analogs, spin-labeled either at C(4) or C(5) is reported as well as their enzymatic incorporation into ribonucleic acids, some of which had previously been shown to be potent interferon inducers upon annealing with poly (inosinic acid). Also, the synthesis of spin-labeled poly (cytidylic acid) obtained by chemical acylation is presented. |