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A THEORETICAL STUDY OF ANNULAR TAUTOMERISM OF PYRROLOTETRAZOLES IN THE GAS PHASE

Vadim Yu. Zubarev, Rostislav E. Trifonov, Vladimir A. Ostrovskii, Dietrich Moderhack
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Abstract


The structure and tautomerism of pyrrolotetrazoles have been studied with quantum-chemical methods (HF/6-31G** and DFT B3LYP/ ANO-S) in the gas phase. According to the calculations of the total energies of various prototropic forms of these heterocyclic systems (1Н-, 3Н-, 5Н- and 7Н-tautomers), it was shown that for unsubstituted pyrrolotetrazole and its derivatives containing methyl substituents at the carbon atom(s), the most stable form is the 5Н-tautomer where aromaticity of the tetrazole fragment is maintained. On the contrary, for pyrrolotetrazoles with electron-withdrawing substituents (CN or Cl), the most stable form is the 1Н-tautomer, where the pyrrole fragment is aromatic. This effect may be determined by the differences of the relative electron accepting of the heterocyclic half-rings.

How to Cite
Zubarev, V. Yu.; Trifonov, R. E.; Ostrovskii, V. A.; Moderhack, D. Chem. Heterocycl. Compd. 2015, 51, 246. [Khim. Geterotsikl. Soedin. 2015, 51, 246.]

For this article in the English edition see DOI 10.1007/s10593-015-1692-7


Keywords


pyrrolotetrazoles; aromaticity; HF and DFT calculations; tautomerism; total energies

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