Synthesis and Rearrangement of 3′-α-Diethylphosphono-3′-β-O-methanesulfonyluridines

Preparation of a uridine derivative bearing both diethylphosphono and methanesulfonate substituents at the 3′-position has been accomplished by reaction of the corresponding α-hydroxy phosphonate with methanesulfinyl chloride and subsequent oxidation. While this methanesulfonate did not undergo elimination under standard reaction conditions, treatment with TBAF results in a novel rearrangement leading to the corresponding 2′-phosphate.