C6-substituted purine derivatives: an experimental and theoretical 1H, 13C and 15N NMR study.

We measured the (1)H, (13)C and (15)N chemical shifts for a series of purine derivatives bearing a norbornane substituent in position 9 and various substituents in position 6. The experimental data were complemented with density functional theory (DFT) calculations. The comparison of the calculated and experimental chemical shifts provided us with information about the tautomer and conformational equilibria of the studied compounds.