The Tautomerism of Pyrazolines (Dihydropyrazoles)

Alkorta, Ibón; Elguero, José

doi:10.4067/s0717-97072015000200022

Cited by 10 publications

(5 citation statements)

References 6 publications

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“…143,144,170 The first paper 143 20. 144 We devoted a paper 170 to the analysis of two publications by Hamme II et al and these are summarized in Scheme 56. 171,172 Scheme 56.…”

Section: Computational Resultsmentioning

confidence: 99%

3-Pyrazolines (2,3-dihydro-1H-pyrazoles): synthesis, reactivity, and physical and biological properties

Hoz¹,

Claramunt²,

Elguero³

et al. 2021

Arkivoc

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“…143,144,170 The first paper 143 20. 144 We devoted a paper 170 to the analysis of two publications by Hamme II et al and these are summarized in Scheme 56. 171,172 Scheme 56.…”

Section: Computational Resultsmentioning

confidence: 99%

3-Pyrazolines (2,3-dihydro-1H-pyrazoles): synthesis, reactivity, and physical and biological properties

Hoz¹,

Claramunt²,

Elguero³

et al. 2021

Arkivoc

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“…Thus, the major compound 6a proved to be the 16α-H, 17α-H compound while 6b was the 16β-H,17β-H diastereomer (Scheme 1). This can be explained by the tendency of 1-unsubstituted Δ 2 -pyrazolines, such as 4 , to tautomerize under heating or in the presence of an acid [38], and the driving force of the tautomeric equilibrium to be shifted toward 4 - T 3 is the extended conjugation, especially in product 6 after acetylation. A significant difference (Δ δ = 0.37) between the chemical shift values of the equivalent protons of 18-CH 3 was actually observed by comparing the 1 H-NMR spectra of 6a and 6b .…”

Section: Resultsmentioning

confidence: 99%

Microwave-Assisted Stereoselective Heterocyclization to Novel Ring d-fused Arylpyrazolines in the Estrone Series

et al. 2019

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Microwave-assisted syntheses of novel ring d-condensed 2-pyrazolines in the estrone series were efficiently carried out from steroidal α,β-enones and hydrazine derivatives. The ring-closure reaction of 16-benzylidene estrone 3-methyl ether with hydrazine in acetic acid resulted in a 2:1 diastereomeric mixture of two 16,17-cis fused pyrazolines, which is contrary to the former literature data for both stereoselectivity and product structure. However, the cyclization reactions of a mestranol-derived unsaturated ketone with different arylhydrazines in acidic ethanol furnished the heterocyclic products in good to excellent yields independently of the substituents present on the aromatic ring of the reagents applied. The MW conditions also permitted the ring-closure reaction with p-nitrophenylhydrazine which is unfavorable under conventional heating. Moreover, the transformations led to the heterocyclic compounds stereoselectively with a 16α,17α-cis ring junction without being susceptible to spontaneous and promoted oxidation to pyrazoles.

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“…2). Tautomerism of pyrazolines is possible and it was reported that tautomer I is more stable than tautomer II, as shown in Figure 2 (Alkorta and Elguero, 2015).…”

Section: Introductionmentioning

confidence: 96%

Design, synthesis, characterization, and cytotoxicity activity evaluation of mono-chalcones and new pyrazolines derivatives

Ali¹,

Murwih²,

Melati³

et al. 2020

J App Pharm Sci

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The development of resistance and side effects of chemotherapeutic drugs are common obstacles in the treatment of cancer. With the expansion of health problems nowadays, there is a need to continuously develop new drugs that are more efficient in targeting tumor cells and safe to normal cells. This study designed a series of new chalcones and pyrazoline derivatives based on their binding energy from the molecular docking study. The synthesis involved Claisen-Schmidt condensation to form two chalcones, 1 and 2, which are then cyclized at room temperature to form eight new pyrazoline derivatives, 3-10. A one-pot reaction of acetophenone, 2-ethoxybenzaldehyde, and hydrazide derivatives (thiosemicarbazide and phenyl hydrazide) under reflux formed two new pyrazoline derivatives, 11 and 12, without the isolation of chalcones. All the synthesized chalcones and pyrazolines were characterized using the Fourier transform infrared spectroscopy-attenuated total reflectance and nuclear magnetic resonance (1D and 2D). The cytotoxicity activity of the chalcones and new pyrazoline compounds were investigated against breast cancer cell lines (MCF-7 and MD-MB-231) and normal breast cell lines (MCF-10A). The results show that only compound 7 showed the minimum inhibition against MCF-7 with IC 50 6.50 µM when exposed to the cell line for 24 hours compared to the reference Gefitinib anticancer drug.

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The Tautomerism of Pyrazolines (Dihydropyrazoles)

Cited by 10 publications

References 6 publications

3-Pyrazolines (2,3-dihydro-1H-pyrazoles): synthesis, reactivity, and physical and biological properties

3-Pyrazolines (2,3-dihydro-1H-pyrazoles): synthesis, reactivity, and physical and biological properties

Microwave-Assisted Stereoselective Heterocyclization to Novel Ring d-fused Arylpyrazolines in the Estrone Series

Design, synthesis, characterization, and cytotoxicity activity evaluation of mono-chalcones and new pyrazolines derivatives

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