TY - JOUR
T1 - 1H, 13C and 15N NMR assignments of phenazopyridine derivatives
AU - Burgueño-Tapia, Eleuterio
AU - Mora-Pérez, Yolanda
AU - Morales-Ríos, Martha S.
AU - Joseph-Nathan, Pedro
PY - 2005/3
Y1 - 2005/3
N2 - Phenazopyridine hydrochloride (1), a drug in clinical use for many decades, and some derivatives were studied by one- and two-dimensional 1H, 13C and 15N NMR methodology. The assignments, combined with DFT calculations, reveal that the preferred protonation site of the drug is the pyridine ring nitrogen atom. The chemoselective acetylation of phenazopyridine (2) and its influence on the polarization of the azo nitrogen atoms were evidenced by the 15N NMR spectra. Molecular calculations of the phenazopyridines 2-4 show that the pyridine and phenyl groups are oriented in an antiperiplanar conformation with intramolecular hydrogen bonding between the N-b atom and the C-2 amino group preserving the E-azo stereochemistry.
AB - Phenazopyridine hydrochloride (1), a drug in clinical use for many decades, and some derivatives were studied by one- and two-dimensional 1H, 13C and 15N NMR methodology. The assignments, combined with DFT calculations, reveal that the preferred protonation site of the drug is the pyridine ring nitrogen atom. The chemoselective acetylation of phenazopyridine (2) and its influence on the polarization of the azo nitrogen atoms were evidenced by the 15N NMR spectra. Molecular calculations of the phenazopyridines 2-4 show that the pyridine and phenyl groups are oriented in an antiperiplanar conformation with intramolecular hydrogen bonding between the N-b atom and the C-2 amino group preserving the E-azo stereochemistry.
KW - 2D NMR
KW - C NMR
KW - H NMR
KW - N NMR
KW - NMR
KW - Phenazopyridine derivatives
UR - http://www.scopus.com/inward/record.url?scp=18044388188&partnerID=8YFLogxK
U2 - 10.1002/mrc.1542
DO - 10.1002/mrc.1542
M3 - Artículo
SN - 0749-1581
VL - 43
SP - 256
EP - 260
JO - Magnetic Resonance in Chemistry
JF - Magnetic Resonance in Chemistry
IS - 3
ER -