Spectral and Quantum-Chemical Study of Nonequivalence of Methylene Protons in 1,4-Dihydropyridine Derivatives*
- 111 Downloads
Structural characteristics of 1,4-dihydropyridines influencing the nonequivalence of the diastereotopic methylene protons in substituents at positions 2 and 6 were studied. The combined effect of magnetically anisotropic groups and intramolecular hydrogen bonds leads to a considerable difference in the chemical shifts of the methylene protons of the AB system. The unusual reversible temperature evolution of these proton signals in monocyclic 1,4-dihydropyridines is associated with two simultaneous conformational processes. It was estimated that the energetically most favorable conformations are stabilized by an intramolecular СН⋯О hydrogen bond.
Keywords1,4-dihydropyridines 1Н NMR spectroscopy hydrogen bond nonequivalence of methylene protons quantum-chemical calculations
This project was supported by the Latvian National Research Program “Biomedicine”.
- 3.I. P Skrastins, V. V. Kastron, B. S. Cekavicus, A. E. Sausins, R. M. Zolotoyabko, and G. J. Duburs, Khim. Geterotsikl. Soedin., 1230 (1991). [Chem. Heterocycl. Compd., 27, 989 (1991).]Google Scholar
- 4.A. Urtti, Z. Hyvonen, A. Plotniece, N. Makarova, I. Reine, G. Tirzitis, B. Vigante, B. Cekavicus, A. Shmidlers, A. Krauze, R. Zhalubovskis, G. Duburs, M. Turunen, S. Yla-Herttuala, I. Jaaskelainen, and M.-R. Toppinen, US Pat. Appl. 20030064954.Google Scholar
- 8.T. Yamada, H. Miki, I. Aoki, and A. Otomo, Opt. Mater. (Amsterdam, Neth.), 35, 2194 (2013).Google Scholar
- 12.M. Thenmozhi, T. Kavitha, B. P. Reddy, V. Vijayakumar, and M. N. Ponnuswamy, Acta Crystallogr., Sect. E: Struct. Rep. Online, 65, o2795 (2009).Google Scholar
- 13.M. Mahendra, B. H. Doreswamy, P. Adlakha, K. Raval, A. Shah, S. M. Anandalwar, and J. S. Prasad, Anal. Sci.: X-Ray Struct. Anal. Online, 21, x35 (2005).Google Scholar
- 15.I. P. Sekacis, E. E. Liepinsh, and G. J. Duburs, Izv. Akad. Nauk LatvSSR, Ser. Khim., 1, 111 (1979).Google Scholar
- 16.C. Giacovazzo, H. L. Monaco, G. Artioli, D. Viterbo, G. Ferraris, G. Gilli, G. Zanotti, and M. Catti, Fundamentals of Crystallography, 2nd ed., Oxford University Press, Oxford (2002), p. 848.Google Scholar
- 18.Jaguar, Version 8.0, Schrodinger, LLC, New York (2011).Google Scholar