Design and Synthesis of α-Carboxy Phosphononucleosides

Rhodium catalyzed O−H insertion reactions employing α-diazophosphonate <b>20</b> with appropriately protected thymidine, uridine, cytosine, adenosine and guanosine derivatives leads to novel 5′-phosphononucleoside derivatives. Deprotection led to a novel series of phosphono derivatives bearing a carboxylic acid moiety adjacent to the phosphonate group with potential antiviral and/or anticancer activity. The phosphononucleosides bearing an α−carboxylic acid group are envisaged as potential diphosphate mimics. Conversion to mono- and diphosphorylated phosphononucleosides has been effected for evaluation as nucleoside triphosphate mimics. Most of the novel phosphononucleosides proved to be inactive against a variety of DNA and RNA viruses. Only the phosphono AZT derivatives <b>56</b>−<b>59</b> showed weak activity against HIV-1 and HIV-2.