Tautomerism of aza cycles: II. Synthesis and structure of 5-substituted 3-(2-hydroxyethylsulfanyl)-1H-1,2,4-triazoles and their salts. Preference of the 1H,4H-1,2,4-triazolium tautomers

Бузыкин, Б. И.; Миронова, Е. В.; Набиуллин, В. Н.; Azancheev, N. M.; Avvakumova, L. V.; Ризванов, И. Х.; Gubaidullin, А. Т.; Литвинов, И. А.; Syakaev, Victor V.

doi:10.1134/s1070363208030225

Cited by 18 publications

(4 citation statements)

References 41 publications

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“…The fused triazole-pyrimidine-benzotheino and the phenyl ring is coplanar with the dihedral angle 2.584 (3)°. The triazole ring is essentially planar similar to those reported earlier (Belcher & Squattrito, 2006;Buzykin et al, 2008) with maximum deviation of atomsfrom their mean statistical planes being 0.0028 (3) Å. The N(1), atom of the triazole ring is in planar trigonal configuration similar to those reported earlier (Lipson et al, 2006).…”

Section: Data Collectionsupporting

confidence: 84%

“…For the biological activity of thiophenes, benzothiophenes, pyrimidines and triazolopyrimidines, see: Shishoo & Jain (1992); Bradbury & Rivett (1991); Elslager et al (1981); Yunosov et al (1966); Blain et al (1982). For related structures, see: Akkurt et al (2008); Buzykin et al (2008); Harrison et al (2006); Lipson et al (2006); Belcher & Squattrito (2006). For hydrogen-bond motifs, see: Bernstein et al 1995).…”

Section: Related Literaturementioning

confidence: 99%

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2-Phenyl-8,9,10,11-tetrahydro-1-benzothieno[3,2-e][1,2,4]triazolo[1,5-c]pyrimidine

et al. 2011

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In the title compound, C17H14N4S, the benzothieno moiety is fused at one end of the pyramidine ring while the triazole ring with a phenyl substituent is fused at the other side. The triazole ring is almost planar [maximum deviation = 0.0028 (3) Å] while the cyclohexane ring adopts a half-chair conformation. In the crystal, pairs of intermolecular C—H⋯N hydrogen bonds form centrosymmetric head-to-head dimers, corresponding to an R 2 2(8) graph-set motif. Further C—H⋯N interactions generate a zigzag chain of molecules along the c axis. The supramolecular assembly is consolidated by π–π stacking interactions [centroid–centroid distance = 3.445 (4) Å].

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Section: Data Collectionsupporting

confidence: 84%

Section: Related Literaturementioning

confidence: 99%

2-Phenyl-8,9,10,11-tetrahydro-1-benzothieno[3,2-e][1,2,4]triazolo[1,5-c]pyrimidine

et al. 2011

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“…Chemists have mostly carried out their investigations on intramolecular tautomerism and intermolecular proton transfer among tautomers during the last decade. − Tautomerism plays an important role in chemical and biological processes. Understanding tautomeric processes is essential in biological processes.…”

Section: Introductionmentioning

confidence: 99%

Barrierless Inter and Intramolecular Proton Transfer; A DFT Study of Tautomerism in Microsolvated and Protonated Systems

Tavakol

2013

J. Phys. Chem. A

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DFT calculations were employed to study tautomers of 2,2-di(pyrimidin-2-yl)acetic acid (DPA) in the gas phase and in the presence of water, methanol, DMSO (microsolvation models), and proton (H(+)). In the gas phase, all three tautomers were in equilibrium with each other (T2 was slightly more favorable); but, in microsolvation with protic solvent, T3 was a major isomer. Moreover, unexpectedly enough, T1 (common form of DPA) was the least stable tautomer in the gas phase, while, in the water (as solvent), T1 was the most stable one. The calculated energy values indicated a very special barrierless tautomeric system between T2 and T3. In the gas phase, ΔG(#) for T2 → T3 was only 0.30 kcal/mol, while it was 56.4 and 44.8 kcal/mol for T2 → T1 and T3 → T1, respectively. Rate constants for conversion of T2 into T3 were high in all cases, and their values in the gas phase and in the presence of water, methanol, DMSO, and proton were 3.6 × 10(12), 3.3 × 10(9), 2.7 × 10(11), 2.3 × 10(12), and 2.3 × 10(12) s(-1), respectively. All types of microsolvation slightly decreased the rate constant of this conversion. The rate constant for conversion of T2 into T1 (1,3-H shift) in the gas phase and in the presence of water, methanol, DMSO, and proton was 3.0 × 10(-29), 2.2 × 10(5), 1.1 × 10(-34), 5.2 × 10(-40), and 4.2 × 10(-26) s(-1), respectively. These values showed that only microsolvation with water strongly increased rate constants of tautomerism for T2 → T1 and this type of tautomerism was impossible in the gas phase or other microsolvation models. Although using water as the solvent enhanced rate constants of all types of tautomeric interconversions, its enhancement was less than that of microsolvation with water.

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“…Because of this tautomerism versatility, AHs have been the subject of interest by chemists. In recent years, the theoretical study of tautomerism in organic compounds received renewed attention because of the importance of tautomerism on compound's application19–22. For example, tautomerism in keto‐enol23, 24, imine‐enamine25, 26, purines27, pirimidines28, and many other systems29–32 have been studied.…”

Section: Introductionmentioning

confidence: 99%

Kinetic and thermodynamic study of inter‐ and intramolecular proton transfer in N′‐acetyl formohydrazide tautomers

Tavakol

2010

Int J of Quantum Chemistry

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Nine tautomers and eleven possible tautomeric interconversions of N 0 -acetyl formohydrazide have been studied at B3LYP/6-311þþG** level of theory. From these calculations, optimized geometries, molecular parameters, IR frequencies, NMR chemical shifts, and energetic results are obtained. In all tautomers except tautomers 4, E isomer is more stable than Z isomer. Energetic data were used to calculate the energy barriers of tautomeric interconversions and very high energy barriers were obtained for all tautomeric interconversions. Moreover, study of solvent effects on relative stabilities of tautomers and transition states showed that they are similar to those in the gas phase. In addition, intermolecular proton transfer with the assistance of one to three water molecules has been studied and the results showed that activation barriers in water-assisted tautomerism are in general lower than those in the gas phase.

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Tautomerism of aza cycles: II. Synthesis and structure of 5-substituted 3-(2-hydroxyethylsulfanyl)-1H-1,2,4-triazoles and their salts. Preference of the 1H,4H-1,2,4-triazolium tautomers

Cited by 18 publications

References 41 publications

2-Phenyl-8,9,10,11-tetrahydro-1-benzothieno[3,2-e][1,2,4]triazolo[1,5-c]pyrimidine

2-Phenyl-8,9,10,11-tetrahydro-1-benzothieno[3,2-e][1,2,4]triazolo[1,5-c]pyrimidine

Barrierless Inter and Intramolecular Proton Transfer; A DFT Study of Tautomerism in Microsolvated and Protonated Systems

Kinetic and thermodynamic study of inter‐ and intramolecular proton transfer in N′‐acetyl formohydrazide tautomers

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