Formation of novel nucleosides from free base and sugar phosphate: aqueous reaction of 2-aminopyrimidine and ribose-5-phosphate.

The facile formation of glycosylamines suggests that a base liberated by depurination might react at the free C1 position of the sugar phosphate from which it had been hydrolyzed, effectively repurinating the site. Model experiments testing this hypothesis demonstrate that such a reaction does take place. The primary product of a reaction between 2-aminopyrimidine (a model for guanine) and ribose-5-phosphate is characterized by enzymatic and chemical degradation, and UV spectra. It is shown to be a novel nucleoside with the base attached via its exocyclic amino group to the C1 of the ribose-5-phosphate.