Artículos de revistas
Multinuclear Magnetic Resonance And Theoretical Calculations In The Study Of Structure And Tautomerism Of Some 2-amino-n′-(aryl)-benzamidines
Registro en:
Spectrochimica Acta - Part A: Molecular And Biomolecular Spectroscopy. , v. 59, n. 13, p. 3139 - 3145, 2003.
13861425
10.1016/S1386-1425(03)00124-0
2-s2.0-0142124416
Autor
Suwinski J.
Szczepankiewicz W.
Basso E.A.
Tormena C.F.
Freitas M.P.
Rittner R.
Institución
Resumen
1H, 13C and 15N NMR spectra of eight 2-amino-N′-(aryl)-benzamidines and of the parent compound were recorded, and unequivocal chemical shift assignments through the use of COSY, 1H-J resolved, HETCOR and COLOC sequences were performed. 1H and 13C chemical shifts for the nuclei of the benzamidine aromatic ring were not affected by the substituents present at N′-phenyl group, while the substituent effects in the chemical shifts of the same nuclei of N′-phenyl ring were very similar to the ones reported for the corresponding monosubstituted benzenes, indicating that there is no interaction between the two aromatic rings. 15N NMR spectra (DEPT sequence) show just two hydrogenated nitrogen atoms, which confirm that the amino form is the most stable tautomer, but the observation of a sharp signal and two broad signals (15N decoupled spectra), and the corresponding broad signal for the =C-NH2 protons (in the 1H spectra), indicates the occurrence of tautomerism between the amino and imino forms, observable for some of the studied benzamidines. Theoretical calculations lead to the conclusion that these compounds occur mostly as the amino tautomer with Z configuration, which is stabilized by hydrogen bonding. © 2003 Elsevier Science B.V. All rights reserved. 59 13 3139 3145 Patai, S., (1975) The Chemistry of Amidines and Imidates, 1. , Wiley, London Patai, S., Rappoport, Z., (1991) The Chemistry of Amidines and Imidates, 2. , Wiley, London Perrin, C.L., (1991) The Chemistry of Amidines and Imidates, 2, p. 147. , PataiS.RappoportZ. London: Wiley Raczynska, E.D., (1997) J. Chem. Res. (S), p. 214 Hartman, J.S., Yuan, Z., Foxand, A., Nguyen, A., (1996) Can. J. Chem., 74, p. 2131 Fry, D.W., Kraker, A.J., McMichael, A., Ambroso, L.A., Nelson, J.M., Leopold, W.R., Conners, R.W., Bridges, A.J., (1994) Science, 265, p. 1093 Szczepankiewicz, W., Suwinski, J., (1998) Tetrahedron Lett., p. 1785 Saitoh, A., Achiwa, K., Tanaka, K., Morimoto, T., (2000) J. Org. Chem., 65, p. 4227 Naulet, N., Filleux, M.L., Martin, G.J., Pornet, J., (1975) Org. Magn. Reson., 7, p. 326 Oszczapowicz, J., Raczynska, E., Osek, J., (1986) Magn. Reson. Chem., 24, p. 9 Filleux, M.L., Naulet, N., Doric, J.P., Martin, G.J., Pornet, J., Miginiac, L., (1974) Tetrahedron Lett., p. 1435 Jackman, L.M., Jen, T., (1975) J. Am. Chem. Soc., 97, p. 2811 Naulet, N., Martin, G.J., (1979) Tetrahedron Lett., p. 1493 Negrebetskii, V.V., Bogel'fer, L.Y., Sinitsa, A.D., Kol'chenko, V.I., (1981) Zh. Obshch. Khim., 51, p. 1493 Cooper, F.C., Partridge, M.W., (1956) Org. Synth., 36, p. 64 Frisch, M.J., Trucks, C.W., Schlegel, H.B., Scuseria, G.E., Robb, M.A., Cheeseman, J.R., Zakrzewski, V.G., Pople, J.A., Gaussian, Inc., Pittsburgh, PA, 1998Barone, G., Duca, D., Silvestri, A., Gomez-Paloma, L., Riccio, R., Bifulco, G., (2002) Chem. Eur. J., 8, p. 3240 Joseph-Nathan, P., Diaz, E., (1970) Introducción a la Resonáncia Magnética Nuclear, , Limusa: Wiley Breitmaier, E., Voelter, W., (1987) Carbon-13 NMR Spectroscopy, 3rd Ed., , Weinheim: VCH Mason, J., (1983) Chem. Br., 19, p. 654 Charton, M., (1983) Top. Curr. Chem., 114, p. 57 Charton, M., (1987) Prog. Phys. Org. Chem., 16, p. 287 Canto, E.L., Tasic, L., Rittner, R., (2000) Can. J. Anal. Sci. Spectrosc., 45, p. 28 Silverstein, R.M., Webster, F.X., (1998) Spectrometric Identification of Organic Compounds, 6th Ed., , New York: Wiley Krygowski, T.M., Wozniak, K., (1991) The Chemistry of Amidines and Imidates, 2, p. 101. , PataiS.RappoportZ. London: Wiley