Nucleosides as reagents in multicomponent reactions: one-pot synthesis of heterocyclic nucleoside analogues incorporating pyrimidine-fused rings

In this study, a general and efficient protocol for the synthesis of new heterocyclic nucleoside analogues (HNAs), using a four-component coupling reaction of nucleosides, aldehydes, barbituric acid/2-thiobarbituric acid, or dimedone is described. The synthesized HNAs contain a pyrimidine-fused heterocycle coupled to the nucleoside via a C–N linkage. The nucleosides served as amine components and underwent the reaction in the presence of a catalytic amount of tungstophosphoric acid (H3PW12O40, TPA) in EtOH.