How to drive imine–enamine tautomerism of pyronic derivatives of biological interest – A theoretical and experimental study of substituent and solvent effects

Amar, Anissa; Meghezzi, Hacène; Boucekkine, Abdou; Kaoua, Racheddine; Kolli, Bellara

doi:10.1016/j.crci.2009.11.009

Cited by 14 publications

(7 citation statements)

References 42 publications

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“…To understand the electronic effects induced by the deprotonation on the stability of the 5FU anions, NBO analysis using MP2/6-31+G(d,p) data in water was carried out, and correlated well with changes in bond lengths in 5FU and its anions under hydration. In this analysis, a stabilization energy E (2) , related to the delocalization trend of electrons from donor to acceptor orbitals, was calculated via perturbation theory. If the stabilization energy E (2) between a donor bonding orbital and an acceptor orbital is large, there is a strong interaction between them.…”

Section: Resultsmentioning

confidence: 99%

Tautomeric Equilibria of 5-Fluorouracil Anionic Species in Water

2010

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It has long been postulated that rare tautomeric or ionized forms of nucleic acid bases may play a role in mispair formation. Therefore, ab initio quantum chemical investigations on the tautomeric equilibrium in 5-fluorouracil (5FU) and its anions (deprotonated from N1, AN1, and from N3, AN3) and their tautomeric forms in water were performed. The effect of the water as solvent was introduced using solute-solvent clusters (four water molecules). The influence of the water molecules on the tautomeric reactions between different forms was considered by multiple proton transfer mechanisms. We show that when a water dimer is located in the reaction site between the two pairs of N-H and C═O groups, the assistive effect of the water molecules is strengthened. All calculations of the solute-water complexes were carried out at an MP2 level of theory and supplemented with correction for higher order correlation terms at CCSD(T) level, using the 6-31+G(d,p) basis set. The ab initio calculated frequencies and Raman intensities of 5FU and its anions AN1, AN3, and dianion are in good agreement with the experimental Raman frequencies in aqueous solution at different pH. In order to establish the pH-induced structural transformation in the molecule of 5FU, further (1)H, (19)F, and (13)C NMR spectra in water solution for pH = 6.9-13.8 were acquired and the chemical shift alterations were determined as a function of pH. On the basis of NMR spectroscopic data obtained for 5FU in aqueous solution at alkaline pH, we suggest the existence of a mixture of the anionic tautomeric forms predicted by our theoretical calculations.

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Section: Resultsmentioning

confidence: 99%

Tautomeric Equilibria of 5-Fluorouracil Anionic Species in Water

2010

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“…Through the ratio of the protons behind each signal, we found that the molar fractions being 70-84 % for the enamine form and 30-16 % for the total imines, respectively. [28] The enamine was stabilized by intramolecular hydrogen bond N34À H34⋅⋅⋅O36 that produced a six membered ring (Scheme 3 and Figure 1). Two imines have the same amount in equili-Scheme 1.…”

Section: Resultsmentioning

confidence: 99%

Synthesis and Biological Evaluation of Azacrownophanes Containing Tetrahydropyridine or Piperidone Subunits

et al. 2022

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Herein we presented the synthesis of azacrownophanes containing tetrahydropyridine or piperidone rings. The multicomponent reactions were performed and afforded tetrahydropyridine or piperidone derivatives which strongly depended on used substrates. Structure of tetrahydropyridine and piperidone derivatives was differentiated by spectrometry methods such as IR, HRMS, NMR and single‐crystal Xray diffraction. Eight synthesized compounds were evaluated for their cytotoxicity through Sulforhodamine B (SRB) assay. Three tetrahydropyridine derivatives displayed the most potent cytotoxic activity against Hep‐G2 and Lu‐1 cell lines with the IC50 values around 8 μM and 31.62 μM, respectively. The screening result of antimicrobial activities of all compounds showed negative values at a tested concentration of 50 μg/ml. The ADME study was calculated to provide some useful information about the structure and bioactivity relationship.

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“…A summary of the data collection process, along with the refinement parameters and selective bond lengths and angles, is provided in Tables S1 and S2 , respectively. It is known that dehydroacetic acid and its related imine derivatives exist in enol imine, enamine ketone, and imine ketone tautomeric forms [ 31 , 32 , 33 ], as shown in Scheme 3 .…”

Section: Resultsmentioning

confidence: 99%

Ring-Opening Polymerization of ε-Caprolactone and Styrene Oxide–CO2 Coupling Reactions Catalyzed by Chelated Dehydroacetic Acid–Imine Aluminum Complexes

Wang

et al. 2021

Molecules

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A series of chelated dehydroacetic acid–imine-based ligands L1H~L4H was synthesized by reacting dehydroacetic acid with 2-t-butylaniline, (S)-1-phenyl-ethylamine, 4-methoxylbenzylamine, and 2-(aminoethyl)pyridine, respectively, in moderate yields. Ligands L1H~L4H reacted with AlMe3 in toluene to afford corresponding compounds AlMe2L1 (1), AlMe2L2 (2), AlMe2L3 (3), and AlMe2L4 (4). All the ligands and aluminum compounds were characterized by IR spectra, 1H and 13C NMR spectroscopy. Additionally, the ligands L1H~L4H and corresponding aluminum derivatives 1, 3, and 4 were characterized by single-crystal X-ray diffractometry. The catalytic activities using these aluminum compounds as catalysts for the ε-caprolactone ring-opening polymerization (ROP) and styrene oxide-CO2 coupling reactions were studied. The results show that increases in the reaction temperature and selective solvent intensify the conversions of ε-caprolactone to polycaprolactone. Regarding the coupling reactions of styrene oxide and CO2, the conversion rate is over 90% for a period of 12 h at 90 °C. This strategy dispenses the origination of cyclic styrene carbonates, which is an appealing concern because of the transformation of CO2 into an inexpensive, renewable and easy excess carbon feedstock.

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How to drive imine–enamine tautomerism of pyronic derivatives of biological interest – A theoretical and experimental study of substituent and solvent effects

Cited by 14 publications

References 42 publications

Tautomeric Equilibria of 5-Fluorouracil Anionic Species in Water

Tautomeric Equilibria of 5-Fluorouracil Anionic Species in Water

Synthesis and Biological Evaluation of Azacrownophanes Containing Tetrahydropyridine or Piperidone Subunits

Ring-Opening Polymerization of ε-Caprolactone and Styrene Oxide–CO2 Coupling Reactions Catalyzed by Chelated Dehydroacetic Acid–Imine Aluminum Complexes

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