Studies of the Tautomerism of Purine and the Protonation of Purine and Its 7- and 9-Methyl Derivatives by Nitrogen-15 Nuclear Magnetic Resonance Spectroscopy

Article abstract of DOI:10.1021/ja00375a038

The nitrogen-15 NMR shifts of purine and its 7- and 9-methyl derivatives were measured at the natural-abundance level as a function of pH.The results made it possible for both the sites and magnitudes of protonation of purine and its derivatives to be determined.A semiquantitative determination was made of the position of the N7H-N9H tautomeric equilibria of purine in both water and dimethyl sulfoxide.