New Chemical Modification of the Ribosyl Moiety in Uridines. : Synthesis of Novel Types of 3', 5'-Epithio Uridine Derivatives

Treatment of 5-substituted 5′-S-acetyl-2,2′-anhydro-5′-thio-1-β-D-arabinofuranosyluracils (2), prepared with ease from 5-substituted 2′,5′-dichloro-2′,5′-dideoxyuridines (1), with methanolic sodium methoxide gave the corresponding 3′,5′-epithio-3′,5′-dideoxy-1-β-D-xylofuranosyluracils (3) fused with a thietane ring in the sugar moiety.