Abstract
4-Substituted 1,5-naphthyridines and their N-oxides were synthesized, and their structures and properties were studied. The IR and UV spectra of 4-hydroxy- and 4-methoxy-1,5-naphthyridines and their 1-oxides and 1-ethyl-4-oxo-1,4-dihydro-1,5-naphthyridine were examined. It is shown that 4-hydroxy-1,5-naphthyridine and its 1-oxide exist in the crystalline state in the lactam form. A quantitative estimate of the position of the tautomeric equilibrium of 4-hydroxy-1,5-naphthyridine as a function of the polarity of the solvent is given, and the tautomeric equilibrium constants and the percentages of the lactim form are calculated. The basicity constants of 4-chloro-, 4-methoxy-, 4-hydrazino-, 4-methylthio-, 4-acetamido-, and 4-amino-1,5-naphthyridines were measured. A comparison of the calculated and experimental pKa data provides evidence in favor of the fact that the compounds are protonated at the N1 atom. A correlation of the basicity constants with the σ substituent constants is examined.
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I. V. Persianova, Yu. N. Sheinker, R. M. Titkova, and A. S. Elina, Khim. Geterotsikl. Soedin., No. 7, 965 (1977).
W. W. Paudler, D. I. Pokorny, and S. I. Cornrich, J. Heterocycl. Chem., 7, 291 (1970).
A. S. Elina, I. S. Musatova, and L. G. Tsyrul'nikova, Khim.-Farm. Zh., No. 8, 6 (1971).
D. N. Bailey, D. M. Hercules, and T. D. Eck, Anal. Chem., 39, 877 (1967).
S. Masson, J. Chem. Soc., No. 23, 5010 (1957).
A. R. Katritzky and J. M. Lagowski, Advances in Heterocyclic Chemistry, Vol. 1, Academic Press, New York (1963), p. 328.
I. Clark and D. D. Perrin, Quart. Rev., 18, 295 (1964).
D. D. Perrin, J. Chem. Soc., No. 24, 5590 (1965).
D. D. Perrin, Dissociation Constants of Bases in Aqueous Solution, London (1965).
E. V. Brown, S. R. Mitchell, and A. C. Plasz, J. Org. Chem., 40, 2368 (1975).
A. Albert and I. N. Phillips, J. Chem. Soc., No. 3, 1294 (1956).
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Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 792–799, June, 1981.
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Titkova, R.M., Elina, A.S., Trifonova, E.A. et al. Synthesis and properties of 4-substituted 1,5-naphthyridines and their N-oxides. Chem Heterocycl Compd 17, 583–590 (1981). https://doi.org/10.1007/BF00503484
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DOI: https://doi.org/10.1007/BF00503484