5-Methyl-2'-deoxy-4'-thio-alpha-uridine (R)-S-oxide.

The pyrimidine ring of the title compound, C(10)H(14)N(2)O(5)S, is planar to within 0.024 (1) A and makes an angle of 75.46 (10) degrees with the mean plane of the thiosugar ring. In terms of standard nucleoside nomenclature, this ring has the C3'-endo conformation. The O5'-C5'-C4'-C3' torsion angle is 166.5 (3) degrees and the glycosidic torsion angle S4'-C1'-N1-C2 is -52.1 (2) degrees (syn).