Synthesis of Chiral Acyclic Nucleosides by Sharpless Asymmetric Dihydroxylation: Access to Cidofovir and Buciclovir

An efficient method to construct chiral acyclic nucleosides via Sharpless asymmetric dihydroxylation of <i>N</i>-allylpyrimidines or <i>N</i>-alkenylpurines is reported. A range of chiral acyclic nucleosides with two adjacent hydroxyl groups present on the side chains could be produced in good yields (up to 97% yield) and excellent enantioselectivities (90–99% ee). The synthetic utility of the reaction was demonstrated by the catalytic asymmetric synthesis of (<i>S</i>)-Cidofovir and (<i>R</i>)-Buciclovir.