Computational investigation at the BHandHLYP/6-311+G(d,p) level of theory of the gas-phase tautomerism of 2- and 4-pyridones confirmed the slight prevalence of lactim in the case of the former, but its dominance in the case of the latter, as shown previously. Examination of aromaticity by using HOMA, EDDB, NBOdel, NICS and AICD led to the conclusion that tautomerization of 4-pyridone results in greater aromaticity gain. It is also driven by the Pauli repulsion relief, which was revealed by the tautomerization energy decomposition analysis. By contrast, in the case of 2-pyridone, lactim is favoured by orbital and electrostatic interactions and disfavoured by the Pauli repulsion. Aromaticity gain in this case is smaller. The position of the tautomeric equilibrium can be modulated by substituent inductive effects (Cl and F), inductive and resonance effects (NH and NO), hydrogen bonding (NO), and medium polarity, the increase of which increases lactam population.
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1039/d3ob01588b | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
The Reaction of Fenchone and Camphor Hydrazones with 5-Acyl-4-Pyrones as a Method for the Synthesis of New Polycarbonyl Conjugates: Tautomeric Equilibrium and Antiviral Activity.
Chem Biodivers
September 2024
Institute of Natural Sciences and Mathematics, Ural Federal University, 620000, Ekaterinburg, Russian Federation.
Selective synthesis of polycarbonyl conjugates of (+)-fenchone and (+)-camphor was carried out (44-91 % yields) via the ring-opening transformation of 5-acyl-4-pyrones with hydrazones of the corresponding monoterpenoids. A strong influence of the hydrazone fragment on the observed tautomeric equilibrium of the tricarbonyl system was shown. Although the major tautomer of the conjugates is the acyclic polycarbonyl form, the camphor-based conjugates undergo new type of ring-chain tautomerism, diketoenaminone-dihydropyridone equilibrium, and predominantly exist in the cyclic dihydropyridone form in DMSO-d.
View Article and Find Full Text PDFTheoretical investigation of tautomerism of 2- and 4-pyridones: origin, substituent and solvent effects.
Org Biomol Chem
December 2023
University of Belgrade - Institute of Chemistry, Technology and Metallurgy - Center for Chemistry, Njegoševa 12, P. O. Box 473, 11000 Belgrade, Serbia.
Computational investigation at the BHandHLYP/6-311+G(d,p) level of theory of the gas-phase tautomerism of 2- and 4-pyridones confirmed the slight prevalence of lactim in the case of the former, but its dominance in the case of the latter, as shown previously. Examination of aromaticity by using HOMA, EDDB, NBOdel, NICS and AICD led to the conclusion that tautomerization of 4-pyridone results in greater aromaticity gain. It is also driven by the Pauli repulsion relief, which was revealed by the tautomerization energy decomposition analysis.
View Article and Find Full Text PDFSynthesis of Multifunctionalized 2,3-Dihydro-4-pyridones and 4-Pyridones via the Reaction of Carbamoylated Enaminones with Aldehydes.
J Org Chem
November 2018
Institute of Natural Sciences and Mathematics , Ural Federal University, 620000 Ekaterinburg , Russian Federation.
The novel and effective diastereoselective synthesis of multifunctionalized dihydropyridones, including CF-substituted derivatives, has been developed on the basis of the piperidine-promoted domino reaction of carbamoylated enaminones with aldehydes. The products have been prepared in 38-90% yields and can be easily isolated by crystallization. Tautomerism, epimerization, and atropisomerism of dihydropyridones have been studied.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!