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 N-allylpyrimidines or N-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 ( S)-Cidofovir and ( R)-Buciclovir.