Synthesis of 1-(β-D-Ribofuranosyl) urea and Related Compounds.

1-(β-D-Ribofuranosyl) urea (VII) was synthesized via. 2,3,5-tri-O-benzoyl-β-D-ribofuranosyl isocyanate (II) and 1-(2,3,5-tri-O-benzoyl-β-D-ribofuranosyl) urea (V). One of the intermediate, V, which is an important starting material for the synthesis of ribonucleosides, was obtained in a yield of 70.5% by direct ammonolysis at 0°of the reaction mixture of 2,3,5-tri-O-benzoyl-D-ribofuranosyl chloride and silver isocyanate. The structure of V was confirmed by converting it to (β-D-ribofuranosyl) thymine.