The experimental and theoretical study of tautomerism of 3-substituted 2-methyl-quinoline-4 (1h)-ones

V. O. Zubkov, O. B. Rozhenko, N. I. Ruschak, S. I. Gritsenko


4-Hydroxy-/4-oxo tautomerism in the series of 3-substituted 2-methyl-quinolin-4(1H)-ones has been studied by 13C NMR-spectroscopy and quantum-chemical methods in various approximations (restricted Hartree-Fock method, DFT and MP2) for the isolated molecules and for solutions using empirical correction of effects for solvents (PCM COSMO procedure). Substituents that are different in their nature have no significant influence on the value of the chemical shift of carbon in position C4 of the quinolone cycle. The only exception is the carbon shielding associated with the bromine atom in the molecule of 3-bromo-2-methyl-1,4-dihydroquinoline-4-one. Significant deshielding detected in all cases in 13C NMR-spectra of the carbon nuclei in position 4 of the ring is in favour of the existence of all derivatives studied as 4-oxo forms in DMSO-d6 solution. The experimental and calculated values for the chemical shift of carbon in position C4 of 4-oxo and 4-hydroxy isomers differ considerably and can be used as a criterion for assigning quinolin-4 (1H)-ones to a particular tautomeric form.


quinoline-4(1H)-ones; tautomerism; 13C NMR-spectroscopy; quantum-chemical calculations

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Bisacchi G. S. Journal of Medicinal Chemistry, 2015, Vol. 58(12), pp.4874-82. Cited 11 times. doi:10.1021/jm501881c

De Oliveira I. R., & Juruena M. F. Journal of Clinical Pharmacy and Therapeutics, 2006, Vol. 31(6), pp.523-34. Cited 71 times. doi:10.1111/j.13652710.2006.00784.x

Huse Holly, Marvin Whiteley. Chemical Reviews 111.1, 2010, pp.152-159. Cited 46 times. doi:10.1021/cr100063u

Bisacchi G. S., & Hale M. R. Current Medicinal Chemistry, 2016, Vol. 23(6), pp.520-77., Cited 46 times. doi:10.2174/0929867323666151223095839# sthash.71PG7eRT.dpuf

Mphahlele Malose J., Ahmed M. El-Nahas. Journal of Molecular Structure 688.1, 2004, pp.129-136, Cited 37 times. doi: 10.1016/j.molstruc.2003.10.003

Seixas R. S., Silva A. M., Alkorta I., Elguero J.,Monatshefte für Chemie-Chemical Monthly, 2011, Vol. 142(7), pp.731-742. Cited 8 times. doi:10.1007/ s00706-011-0473-y

Pourmousavi S. A., Kanaani A., Ghorbani F., Damghani K. K., Ajloo D., Vakili M. Research on Chemical Intermediates, 2015, pp.1-38. doi: 10.1007/ s11164-015-2084-4

Chang F.-S., Chen W., Wang C., Tzeng C.-C., Chen Y.-L. Bioorganic and Medicinal Chemistry, 2010, Vol. 18(1), pp.124-133. Cited 40 times. doi:10.1016/j. bmc.2009.11.012

Ukrainets I. V., Bereznyakova N. L., Turov A. V. Chemistry of Heterocyclic Compounds, 2008, Vol. 44(7), pp.833-837. Cited 2 times. doi:10.1007/s10593008-0118-1

Zubkov V. O., Tsapko T. O., Gritsenko I. S., Rushchak N. I. Zhurnal organichnoi ta farmatsevtichnoi khimii – Journal of organic and pharmaceutical chemistry, 2011, Vol. 9, No.4, pp.38-41.

Zubkov V. O., Ruschak N. I., Kamenetska O. L., Gritsenko I. S. Zhurnal organichnoi ta farmatsevtichnoi khimii – Journal of organic and pharmaceutical chemistry, 2015, Vol. 13, No.4, pp.32-36.

Zubkov V. A., Gritsenko I. S., Podolsky I. N., Taran E. A., Zhurnal Organichnoi ta Farmatsevtichnoi Khimii, 2008, Vol. 6(3), pp.48-52.

Klamt Andreas, Schürmann G. Journal of the Chemical Society, Perkin Transactions 2 5, 1993, pp.799-805. Cited 5054 times. doi:10.1039/P29930000799

Wolff S. K., Ziegler T. The Journal of Chemical Physics., 1998, Vol. 109(3), pp.895-905. Cited 259 times. doi:10.1063/1.476630

Mennucci B. Wiley Interdisciplinary Reviews: Computational Molecular Science, 2012, Vol. 2(3), pp.386-404. Cited 87 times. doi:10.1002/wcms.1086

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