Proton transfer in C-halogen pyrazole cyclamers. A theoretical study

Alkorta, Ibón; Blanco, Fernando; Elguero, José

doi:10.1007/s11224-007-9271-x

Cited by 14 publications

(4 citation statements)

References 28 publications

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“…In the same way, apart from solvent contribution, all of the intermolecular interactions with the surrounding environment should be considered whenever hydrogen donation and acceptance processes are possible, independently of the physical state. Theoretical studies, although relying on gas-phase behavior, can also be used to predict solid-state and solution properties, due to the possibility of introducing features inherent to different environments in the calculations, and also because pyrazoles preserve their propensity to aggregate in the gas phase, a feature common to all of the physical states [73,74]. Due to this fact, theoretical studies were shown to display high accordance with experimental results in many of the studies reported herein.…”

Section: Environmental Effectsmentioning

confidence: 66%

Revisiting the Structure and Chemistry of 3(5)-Substituted Pyrazoles

2019

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Pyrazoles are known as versatile scaffolds in organic synthesis and medicinal chemistry, often used as starting materials for the preparation of more complex heterocyclic systems with relevance in the pharmaceutical field. Pyrazoles are also interesting compounds from a structural viewpoint, mainly because they exhibit tautomerism. This phenomenon may influence their reactivity, with possible impact on the synthetic strategies where pyrazoles take part, as well as on the biological activities of targets bearing a pyrazole moiety, since a change in structure translates into changes in properties. Investigations of the structure of pyrazoles that unravel the tautomeric and conformational preferences are therefore of upmost relevance. 3(5)-Aminopyrazoles are largely explored as precursors in the synthesis of condensed heterocyclic systems, namely pyrazolo[1,5-a]pyrimidines. However, the information available in the literature concerning the structure and chemistry of 3(5)-aminopyrazoles is scarce and disperse. We provide a revision of data on the present subject, based on investigations using theoretical and experimental methods, together with the applications of the compounds in synthesis. It is expected that the combined information will contribute to a deeper understanding of structure/reactivity relationships in this class of heterocycles, with a positive impact in the design of synthetic methods, where they take part.

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Section: Environmental Effectsmentioning

confidence: 66%

Revisiting the Structure and Chemistry of 3(5)-Substituted Pyrazoles

2019

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“…Further more, pyrazoles dimerization in the gas phase also has been reported [21][22][23]. On the other hand, the tautomerism and proton transfer in pyrazoles have been communicated [24][25][26][27]. Recently, we studied the solid state structures and anti-microbial activity of some new substituted pyrazoles [28,29].…”

Section: Introductionmentioning

confidence: 94%

Cooperative N–H···N, N–H···O, and O–H···N bonded molecular dimers of two new 3,5-diaryl-1H-pyrazoles

Zheng

Wang

2010

Struct Chem

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Two new 3,5-diaryl-1H-pyrazoles: 3(5)-(4-tertbutylphenyl)-5(3)-(naphthalene-2-yl)-1H-pyrazole (1) and 5-(4-(benzyloxy)phenyl)-3-(furan-2-yl)-1H-pyrazole (2) were synthesized and characterized. Two strong ions peaks [2M] ? and [2M ? Na] ? observed in the ESI-MS spectra are attributed to the dimerization process in solution formed by intermolecular N-HÁÁÁN hydrogen bonds. The crystal structures have been determined by X-ray crystal structure analysis. Compound 1 exists as a pair of tautomers 1a and 1b, and its dimer [R 2 2 (6) motif] is formed by the tautomers 1a and 1b. Compound 2 only exists as a 2a tautomer, and interesting intermolecular N-HÁÁÁO and O-HÁÁÁN hydrogen bonds link two pyrazoles and two methanol molecules, leading to the formation of an R 4 4 (10) dimer motif.

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“…The next is paper by Alkorta et al [79] who used DFT to study proton transfer in four monomers and twelve pyrazole cyclamers unsubstituted or bearing fluoro, chloro, or bromo substituents at positions 3 and 5. This study was initiated as NH-pyrazoles are among the very few substances that show proton transfer in the solid state leading to annular tautomerism.…”

Section: Issuementioning

confidence: 99%