title: NMR study of 5-substituted pyrazolo[3,4-c]pyridine derivatives.
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--(13)C and (1)H--(15)N coupling constants. The (1)H NMR spectra were measured over a broad range of temperatures. All of the compounds were shown to exist predominantly in the N1-H tautomeric form. Complementary quantum-chemical calculations of the chemical shieldings and indirect spin-spin couplings support the structural conclusions drawn.
authors.affiliation: Department of Pharmacy, Division of Pharmaceutical Chemistry, University of Athens, Panepistimiopolis Zografou, Athens GR-15771, Greece.
authors.forename: Orestis
authors.initials: O
authors.lastname: Tsikouris
authors.forename: Tomás
authors.initials: T
authors.lastname: Bartl
authors.forename: Jaromír
authors.initials: J
authors.lastname: Tousek
authors.forename: Nikolaos
authors.initials: N
authors.lastname: Lougiakis
authors.forename: Tony
authors.initials: T
authors.lastname: Tite
authors.forename: Panagiotis
authors.initials: P
authors.lastname: Marakos
authors.forename: Nicole
authors.initials: N
authors.lastname: Pouli
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Mikros
authors.forename: Radek
authors.initials: R
authors.lastname: Marek
mesh_terms: D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D011720:Pyrazoles / Q000138:chemical synthesis / Q000737:chemistry*; D011725:Pyridines / Q000138:chemical synthesis / Q000737:chemistry*; D011789:Quantum Theory; D013237:Stereoisomerism
chemical_list: D011720:Pyrazoles; D011725:Pyridines