Modification of the sugar moiety in uridine via 2',3'-epoxyuridine derivatives.

The reaction of 5'-O-mesyl-2',3'-epoxyuridine or 5'-Oiodo-2',3'-epoxyuridine with a nucleophile gave 2'- and 3'-adducts as a mixture while the use of 4',5'-didehydro-5'-deoxy-2',3'-epoxyuridine as a substrate gave 4',5'-didehydro-5'-deoxy 3'-substituted derivatives as a main product. The slow N3 rearrangement reaction of the 3'-N3 adduct of 4',5'-didehydro-5'-deoxy-2',3'-epoxyuridine to the 5'-N3 adduct was observed in DMSO-d6.