IFLP   13074
INSTITUTO DE FISICA LA PLATA
Unidad Ejecutora - UE
artículos
Título:
Structure of indazole N1-oxide derivatives studied by X-ray, theoretical methods, 1H-, 13C-, 15N NMR and EI/MS
Autor/es:
A. GERPE; O. E. PIRO; H. CERECETTO; M. GONZÁLEZ
Revista:
JOURNAL OF MOLECULAR STRUCTURE
Editorial:
Elsevier
Referencias:
Año: 2007 vol. 871 p. 98 - 107
ISSN:
0022-2860
Resumen:
A series of indazole N1-oxide derivatives has been spectroscopically studied in solution using 1H, 13C, and 15N NMR based on pulsed field gradient selected PFG 1HAX (X=13C and 15N) gHMQC and gHMBC experiments. Some indazoles were prepared using a new methodology to compare its spectral and structural data with the indazole N1-oxide parent compounds. The 13C resonances of the indazole N1-oxide carbon 3 and 7a demonstrate the N-oxide push-electron capability. The 15N resonances of the indazole N-oxide, nitrogen 1, are near to 30 ppm more shielded than the corresponding values in the indazole heterocycle (deoxygenated form). Moreover, the structures of one indazole and one indazole N-oxide were unambiguously confirmed by X-ray crystallography. The solid state structures were contrasted with the theoretical ones obtained in vacuo at different calculus level. The aromaticity of the derivatives was studied analyzing the HAH coupling constants of indazole’s aromatic hydrogens and measuring CAC distances in the solid state. The fragmentation that takes place in EI/MS was gathered for all the indazole N-oxide derivatives and the general fragmentation pattern analyzed.N1-oxide derivatives has been spectroscopically studied in solution using 1H, 13C, and 15N NMR based on pulsed field gradient selected PFG 1HAX (X=13C and 15N) gHMQC and gHMBC experiments. Some indazoles were prepared using a new methodology to compare its spectral and structural data with the indazole N1-oxide parent compounds. The 13C resonances of the indazole N1-oxide carbon 3 and 7a demonstrate the N-oxide push-electron capability. The 15N resonances of the indazole N-oxide, nitrogen 1, are near to 30 ppm more shielded than the corresponding values in the indazole heterocycle (deoxygenated form). Moreover, the structures of one indazole and one indazole N-oxide were unambiguously confirmed by X-ray crystallography. The solid state structures were contrasted with the theoretical ones obtained in vacuo at different calculus level. The aromaticity of the derivatives was studied analyzing the HAH coupling constants of indazole’s aromatic hydrogens and measuring CAC distances in the solid state. The fragmentation that takes place in EI/MS was gathered for all the indazole N-oxide derivatives and the general fragmentation pattern analyzed.