(Nucleosides and nucleotides. LXXIII). Synthesis of 6,5'-cyclo-5'-deoxy-5'(R and S)-(2-hydroxyethyl)-uridines.

Abstract
Oxidation of 6, 5'-cyclo-5'-deoxy-2', 3'-Ο-isopropylideneuridine with selenium dioxide gave the 5'-oxo derivative, which was converted to the 5'-ethoxycarbonylmethylidene derivative (3). Reduction of 3 afforded, after deprotection, the title compounds (6, R and S). The base-catalyzed epimerization of 6 at the 5'-position was observed, and the equilibrium was in favor of the (R) -epimer.