Pyrimidine nucleosides. Part IV. Reactions of 3-(β-D-ribofuranosyl)-uracils

Abstract

The synthesis of 3-(2-deoxy-β-D-ribofuranosyl)uracil is reported. 3-(β-D-ribofuranosyl)uracil (3) was converted into its crystalline triacetate (4) and successfully thiated to give, after removal of the protecting groups, 3-(β-D-ribofuranosyl)-4-thiouracil (6). Bromination of (3) gave 5-bromo-3-(β-D-ribofuranosyl)uracil (7). 6-Methylthio-3-(β-D-ribofuranosyl)uracil was converted into 3-(2,3-O-isopropylidene-5-methylsulphonyl-β-D-ribofuranosyl)-6-methylthiopyrimidine-2,4-dione (12). Reaction of (12) with potassium t-butoxide in NN-dimethylformamide produced two isomeric anhydronucleosides (13) and (14). The reactions of (13) and (14) with methanolic ammonia were investigated.