Abstract Substituted pyrazolopyridines are potent inhibitors of phosphodiesterases and cyclin-dependent kinases. In this study, NMR was used to investigate the potential N1-H and N2-H tautomerism of 5-substituted pyrazolo [3, 4-c] pyridine derivatives. Six compounds were fully characterized by using 1 H, 13 C, and 15 N chemical shifts and indirect 1 H [BOND] 13 C and 1 H [BOND] 15 N coupling constants. The 1 H NMR spectra were ...