An improved procedure for the synthesis of vinylphosphonate-linked nucleic acids

The syntheses of a range of 5′-deoxy-5′-methylidene phosphonate-containing thymidine dimers have been achieved using a palladium-catalysed cross coupling reaction as a key step. The optimised reaction conditions comprising of palladium acetate, 1,1′-bis(diphenylphosphino)ferrocene and propylene oxide in THF were found to couple a range of H-phosphonates and vinyl bromide 3 in fair to excellent yield.