Intramolecular Glycosylation to Form 4-Methoxy-2,6-Dioxopyrimidine Nucleosides via O⁶,5′-Cyclonucleosides

Abstract

Lewis-acid promoted intramolecular N1 glycosylation to form the novel O⁶,5′-cyclonucleoside 1a occurs in high yield from the corresponding acyclic thiophenyl-glycoside 12. The relative stability of the O⁶,5′ tether compared with O²,5′ and O²,3′ tethers is reported. Cleavage of the anhydro bond was effected with aqueous base to yield the 4-methoxybarbituric acid nucleoside analogue 14.