Reaction of Hydrogen Halides on 2,3'-Anhydro-1-(β-D-xylofuranosyl) uracil

2, 3'-Anhydro-1-(β-D-xylofuranosyl) uracil (IV) was allowed to react with sodium iodide in the presence of acetic acid. The major product isolated was proved to be 1-(5'-iodo-5'-deoxy-β-D-xylofuranosyl) uracil (V) whose structure was unambiguously established. The reaction of other halide ions on the anhydronucleoside (IV) furnished the same type of compounds, 1-(5'-chloro-5'-deoxy-β-D-xylofuranosyl) uracil (XVI) and 1-(5'-bromo-5'-deoxy-β-D-xylofuranosyl) uracil (XVII). By treatment of the compound (V) with silver acetate, 2, 3'-anhydro compound (IV) was recovered, and it was supposed that 2, 5'-anhydro-1-(β-D-xylofuranosyl) uracil (XII) initially produced was rearranged to the 2, 3'-anhydro compound (IV) by a nucleophilic attack of 3'-up hydroxyl function of XII at C2 carbon of the uracil moiety.