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Special Issue "Pyrazole Derivatives"

A special issue of Molecules (ISSN 1420-3049). This special issue belongs to the section "Medicinal Chemistry".

Deadline for manuscript submissions: 30 September 2018

Special Issue Editor

Guest Editor
Prof. Dr. Wolfgang Holzer

Division of Drug Synthesis, Department of Pharmaceutical Chemistry, Faculty of Life Sciences, University of Vienna, Althanstrasse 14, 1090 Vienna, Austria
Website | E-Mail
Interests: chemistry of azoles; chemistry of azines; heterocyclic tautomerism; NMR spectroscopy in structural elucidation; medicinal heterocyclic chemistry; chemistry of carbenoides

Special Issue Information

Dear Colleagues,

The pyrazole nucleus has been the core of the first synthetic drug molecule and is still a frequently-occurring motif in many biologically active compounds, including several pharmaceuticals currently on the market. Moreover, pyrazole derivatives have found numerous applications in agrochemicals, dyes, fluorescent materials, and more. Hence, there is ongoing interest in pyrazole chemistry also in recent times, what is reflected by a plethora of correspondent publications.

In this respect, researchers in the field are cordially invited to submit their manuscripts relevant to the synthesis of pyrazoles, pyrazolidines and pyrazolinones, their functionalization and their use in the construction of condensed systems for a Special Issue, ‘Pyrazole Derivatives’, within the journal Molecules. Moreover, contributions regarding spectroscopic data and tautomerism studies with appropriate pyrazole derivatives are welcome.

Prof. Dr. Wolfgang Holzer
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Molecules is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1800 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Synthesis of pyrazoles via ring-closure reactions
  • Functionalization of the pyrazole nucleus
  • Cross-coupling reactions with appropriate pyrazoles
  • N-alkylation and N-arylation of NH-pyrazoles
  • Synthesis of condensed systems starting from pyrazole derivatives
  • Tautomerism of pyrazoles and pyrazolones
  • Bioactive pyrazole derivatives
  • Spectroscopic data of pyrazoles
  • Pyrazole-containing ligands

Published Papers (10 papers)

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Research

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Open AccessArticle Discovery of 4,5-Dihydro-1H-thieno[2′,3′:2,3]thiepino [4,5-c]pyrazole-3-carboxamide Derivatives as the Potential Epidermal Growth Factor Receptors for Tyrosine Kinase Inhibitors
Molecules 2018, 23(8), 1980; https://doi.org/10.3390/molecules23081980
Received: 30 April 2018 / Revised: 25 June 2018 / Accepted: 17 July 2018 / Published: 8 August 2018
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Abstract
The epidermal growth factor receptors (EGFRs), in which overexpression (known as upregulation) or overactivity have been associated with a number of cancers, has become an attractive molecular target for the treatment of selective cancers. We report here the design and synthesis of a
[...] Read more.
The epidermal growth factor receptors (EGFRs), in which overexpression (known as upregulation) or overactivity have been associated with a number of cancers, has become an attractive molecular target for the treatment of selective cancers. We report here the design and synthesis of a novel series of 4,5-dihydro-1H-thieno [2′,3′:2,3]thiepino[4,5-c]pyrazole-3-carboxamide derivatives and the screening for their inhibitory activity on the EGFR high-expressing human A549 cell line using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT). A Docking simulation was performed to fit compound 6g and gifitinib into the EGFR to determine the probable binding models, and the binding sites and modes conformation of 6g and gifitinib were exactly similar, the two compounds were stabilized by hydrogen bond interactions with MET769. Combining with the biological activity evaluation, compound 6g demonstrated the most potent inhibitory activity (IC50 = 9.68 ± 1.95 μmol·L–1 for A549). Conclusively, 4,5-dihydro-1H-thieno[2′,3′:2,3]thiepino[4,5-c]pyrazole-3-carboxamide derivatives as the EGFR tyrosine kinase inhibitors were discovered, and could be used as potential lead compounds against cancer cells. Full article
(This article belongs to the Special Issue Pyrazole Derivatives)
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Open AccessArticle Modification of Boc-Protected CAN508 via Acylation and Suzuki-Miyaura Coupling
Molecules 2018, 23(1), 149; https://doi.org/10.3390/molecules23010149
Received: 8 December 2017 / Revised: 21 December 2017 / Accepted: 11 January 2018 / Published: 12 January 2018
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Abstract
The cyclin-dependent kinase inhibitor, CAN508, was protected with di-tert-butyl dicarbonate to access the amino-benzoylated pyrazoles. The bromo derivatives were further arylated by Suzuki-Miyaura coupling using the XPhos Pd G2 pre-catalyst. The coupling reaction provided generally the para-substituted benzoylpyrazoles in the
[...] Read more.
The cyclin-dependent kinase inhibitor, CAN508, was protected with di-tert-butyl dicarbonate to access the amino-benzoylated pyrazoles. The bromo derivatives were further arylated by Suzuki-Miyaura coupling using the XPhos Pd G2 pre-catalyst. The coupling reaction provided generally the para-substituted benzoylpyrazoles in the higher yields than the meta-substituted ones. The Boc groups were only utilized as directing functionalities for the benzoylation step and were hydrolyzed under conditions of Suzuki-Miyaura coupling, which allowed for elimination of the additional deprotection step. Full article
(This article belongs to the Special Issue Pyrazole Derivatives)
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Open AccessFeature PaperArticle On the Tautomerism of N-Substituted Pyrazolones: 1,2-Dihydro-3H-pyrazol-3-ones versus 1H-Pyrazol-3-ols
Molecules 2018, 23(1), 129; https://doi.org/10.3390/molecules23010129
Received: 27 November 2017 / Revised: 28 December 2017 / Accepted: 30 December 2017 / Published: 9 January 2018
Cited by 1 | PDF Full-text (2466 KB) | HTML Full-text | XML Full-text
Abstract
The tautomerism of 1-phenyl-1,2-dihydro-3H-pyrazol-3-One was investigated. An X-ray crystal structure analysis exhibits dimers of 1-phenyl-1H-pyrazol-3-ol units. Comparison of NMR (nuclear magnetic resonance) spectra in liquid state (1H, 13C, 15N) with those of “fixed” derivatives, as
[...] Read more.
The tautomerism of 1-phenyl-1,2-dihydro-3H-pyrazol-3-One was investigated. An X-ray crystal structure analysis exhibits dimers of 1-phenyl-1H-pyrazol-3-ol units. Comparison of NMR (nuclear magnetic resonance) spectra in liquid state (1H, 13C, 15N) with those of “fixed” derivatives, as well as with the corresponding solid state NMR spectra reveal this compound to exist predominantly as 1H-pyrazol-3-ol molecule pairs in nonpolar solvents like CDCl3 or C6D6, whereas in DMSO-d6 the corresponding monomers are at hand. Moreover, the NMR data of different related 1H-pyrazol-3-ol derivatives are presented. Full article
(This article belongs to the Special Issue Pyrazole Derivatives)
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Open AccessArticle Synthesis, Crystal Structure, and Supramolecular Understanding of 1,3,5-Tris(1-phenyl-1H-pyrazol-5-yl)benzenes
Received: 1 December 2017 / Revised: 18 December 2017 / Accepted: 19 December 2017 / Published: 22 December 2017
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Abstract
Understanding the supramolecular environment of crystal structures is necessary to facilitate designing molecules with desirable properties. A series of 12 novel 1,3,5-tris(1-phenyl-1H-pyrazol-5-yl)benzenes was used to assess the existence of planar stacking columns in supramolecular structures of pyrazoles. This class
[...] Read more.
Understanding the supramolecular environment of crystal structures is necessary to facilitate designing molecules with desirable properties. A series of 12 novel 1,3,5-tris(1-phenyl-1H-pyrazol-5-yl)benzenes was used to assess the existence of planar stacking columns in supramolecular structures of pyrazoles. This class of molecules with different substituents may assist in understanding how small structural changes affect the supramolecular environment. The obtained compounds did not present the formation of planar stacking interactions between benzenes in solid or liquid states. This supposition was indicated by single crystal diffraction, Density Functional Theory (DFT) and quantum theory of atoms in molecules (QTAIM) calculations, and concentration-dependent liquid-state 1H nuclear magnetic resonance (NMR). NMR showed that chemical shifts of benzene and pyrazole hydrogens confirm that planar stacking interactions are not formed in solution. The crystalline structures presented different molecular conformations. The molecular structures of 5 and 9b are in a twisted conformation, while compound 7 showed a conformation analogous to a calyx form. Full article
(This article belongs to the Special Issue Pyrazole Derivatives)
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Open AccessArticle 19F‐NMR Diastereotopic Signals in Two N-CHF2 Derivatives of (4S,7R)-7,8,8-Trimethyl-4,5,6,7-tetrahydro-4,7-methano-2H-indazole
Molecules 2017, 22(11), 2003; https://doi.org/10.3390/molecules22112003
Received: 2 November 2017 / Revised: 14 November 2017 / Accepted: 16 November 2017 / Published: 17 November 2017
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Abstract
In this paper, we report the anisochrony of the fluorine atoms of a CHF2 group when linked to a pyrazole ring. The pyrazole is part of (4S,7R)-7,8,8-trimethyl-4,5,6,7-tetrahydro-4,7-methano-2H-indazole also known as (4S,7R)-campho[2,3-c
[...] Read more.
In this paper, we report the anisochrony of the fluorine atoms of a CHF2 group when linked to a pyrazole ring. The pyrazole is part of (4S,7R)-7,8,8-trimethyl-4,5,6,7-tetrahydro-4,7-methano-2H-indazole also known as (4S,7R)-campho[2,3-c]pyrazole, which has two stereogenic centers. Gauge-Independent Atomic Orbital (GIAO)/Becke, 3-parameter, Lee-Yang-Parr (B3LYP)/6-311++G(d,f) calculated 19F chemical shifts of the minimum energy conformations satisfactorily agree with the experimental data. The energy differences between minima need to consider solvent effects (continuum model) to be satisfactorily reproduced. Full article
(This article belongs to the Special Issue Pyrazole Derivatives)
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Open AccessArticle Synthesis and Structure–Activity Relationships of 4-Morpholino-7,8-Dihydro-5H-Thiopyrano[4,3-d]pyrimidine Derivatives Bearing Pyrazoline Scaffold
Molecules 2017, 22(11), 1870; https://doi.org/10.3390/molecules22111870
Received: 6 September 2017 / Revised: 20 October 2017 / Accepted: 25 October 2017 / Published: 31 October 2017
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Abstract
Phosphatidylinositol 3-kinase/Protein kinase B/Mammalian target of rapamycin (PI3K/Akt/mTOR) signaling pathway is abnormally active in the growth and proliferation of cancer cells. The inhibition of PI3K kinase can effectively block the conduction of signaling pathways and is an ideal target for drug design. In
[...] Read more.
Phosphatidylinositol 3-kinase/Protein kinase B/Mammalian target of rapamycin (PI3K/Akt/mTOR) signaling pathway is abnormally active in the growth and proliferation of cancer cells. The inhibition of PI3K kinase can effectively block the conduction of signaling pathways and is an ideal target for drug design. In this paper; two series of 4-morpholino-7,8-dihydro-5H-thiopyrano[4,3-d]pyrimidine derivatives bearing pyrazoline moiety (7a–l; 8a–l) were synthesized; and their cytotoxicity in vitro were evaluated by 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) method against four human cancer cell lines including A549; PC-3; MCF-7; and HepG2 cell lines. The activity of the most promising compound 8d against PI3Kα kinase was further evaluated. The results indicated that most of the target compounds showed moderate to excellent cytotoxicity and the most promising compound 8d showed excellent cytotoxicity against four cancer cell lines with half maximal inhibitory concentration (IC50) values of 6.02–10.27 μM. In addition; the compound 8d was found to have a moderate inhibitory activity in the PI3Kα enzyme assay. What’s more; the compounds of which the substituents of benzene ring at the C-4 position are electron-withdrawing groups such as substituents (Cl; F; Br) have better activity than the compounds containing the electron donating groups (OCH3; H). However; the exact action mechanism is not quite clear right now. Further study will be carried out to identify the exact target in near future. Full article
(This article belongs to the Special Issue Pyrazole Derivatives)
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Open AccessArticle Solvent and Copper Ion-Induced Synthesis of Pyridyl–Pyrazole-3-One Derivatives: Crystal Structure, Cytotoxicity
Molecules 2017, 22(11), 1813; https://doi.org/10.3390/molecules22111813
Received: 12 September 2017 / Revised: 19 October 2017 / Accepted: 24 October 2017 / Published: 25 October 2017
Cited by 1 | PDF Full-text (2489 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Five novel compounds, methyl 5-(acetyloxy)-1-(6-bromo-2-pyridinyl)-1H-pyrazole-3-carboxylate (1), methyl 1-(6-bromo-2-pyridinyl)-5-hydroxy-1H-pyrazole-3-carboxylate (2), Trimethyl 1,1′,1′′-tris(6-bromo-2-pyridinyl)-5,5′′-dihydroxy-5′-oxo-1′,5′-dihydro-1H,1′′H-4,4′: 4′,4′′-terpyrazole-3,3′,3′′-tricarboxylate (H2L1, 3), [Cu2(L2)2]·CH3OH (4), H2L2A·CH3
[...] Read more.
Five novel compounds, methyl 5-(acetyloxy)-1-(6-bromo-2-pyridinyl)-1H-pyrazole-3-carboxylate (1), methyl 1-(6-bromo-2-pyridinyl)-5-hydroxy-1H-pyrazole-3-carboxylate (2), Trimethyl 1,1′,1′′-tris(6-bromo-2-pyridinyl)-5,5′′-dihydroxy-5′-oxo-1′,5′-dihydro-1H,1′′H-4,4′: 4′,4′′-terpyrazole-3,3′,3′′-tricarboxylate (H2L1, 3), [Cu2(L2)2]·CH3OH (4), H2L2A·CH3CN (5) were synthesized. Compounds 15 characterized by elemental analysis, IR, and X-ray single-crystal diffraction. And 13 were also characterized by 1H NMR, 13C NMR and ESI-MS. The H2L1, H2L2 were formed by in-situ reaction. H2L2 and H2L2A are mesomer compounds which have two chiral carbons. The antitumor activity of compounds 15 against BEL-7404, HepG2, NCI-H460, T-24, A549 tumor cell lines were screened by methylthiazolyl tetrozolium (MTT) assay. The compounds 1, 2 showed weakly growth inhibition on the HepG2 cell lines. The HepG2 and A549 cell lines showed higher sensitivity to compound 4, while the IC50 values are 10.66, 28.09 μM, respectively. It is worth noting that compounds 15 did not show cytotoxicity to human normal liver cell line HL-7702, suggesting its cytotoxic selectivity on these tumor cell lines. Full article
(This article belongs to the Special Issue Pyrazole Derivatives)
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Review

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Open AccessReview Synthesis and Pharmacological Activities of Pyrazole Derivatives: A Review
Molecules 2018, 23(1), 134; https://doi.org/10.3390/molecules23010134
Received: 22 November 2017 / Revised: 3 January 2018 / Accepted: 5 January 2018 / Published: 12 January 2018
Cited by 4 | PDF Full-text (35179 KB) | HTML Full-text | XML Full-text
Abstract
Pyrazole and its derivatives are considered a pharmacologically important active scaffold that possesses almost all types of pharmacological activities. The presence of this nucleus in pharmacological agents of diverse therapeutic categories such as celecoxib, a potent anti-inflammatory, the antipsychotic CDPPB, the anti-obesity drug
[...] Read more.
Pyrazole and its derivatives are considered a pharmacologically important active scaffold that possesses almost all types of pharmacological activities. The presence of this nucleus in pharmacological agents of diverse therapeutic categories such as celecoxib, a potent anti-inflammatory, the antipsychotic CDPPB, the anti-obesity drug rimonabant, difenamizole, an analgesic, betazole, a H2-receptor agonist and the antidepressant agent fezolamide have proved the pharmacological potential of the pyrazole moiety. Owing to this diversity in the biological field, this nucleus has attracted the attention of many researchers to study its skeleton chemically and biologically. This review highlights the different synthesis methods and the pharmacological properties of pyrazole derivatives. Studies on the synthesis and biological activity of pyrazole derivatives developed by many scientists around the globe are reported. Full article
(This article belongs to the Special Issue Pyrazole Derivatives)
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Open AccessReview Synthesis of Non-Racemic Pyrazolines and Pyrazolidines by [3+2] Cycloadditions of Azomethine Imines
Received: 29 November 2017 / Revised: 12 December 2017 / Accepted: 12 December 2017 / Published: 21 December 2017
Cited by 1 | PDF Full-text (8603 KB) | HTML Full-text | XML Full-text
Abstract
Asymmetric [3+2] cycloadditions of azomethine imines comprise a useful synthetic tool for the construction of pyrazole derivatives with a variable degree of saturation and up to three stereogenic centers. As analogues of pyrrolidines and imidazolidines that are abundant among natural products, pyrazoline and
[...] Read more.
Asymmetric [3+2] cycloadditions of azomethine imines comprise a useful synthetic tool for the construction of pyrazole derivatives with a variable degree of saturation and up to three stereogenic centers. As analogues of pyrrolidines and imidazolidines that are abundant among natural products, pyrazoline and pyrazolidine derivatives represent attractive synthetic targets due to their extensive applications in the chemical and medicinal industries. Following the increased understanding of the mechanistic aspect of metal-catalyzed and organocatalyzed [3+2] cycloadditions of 1,3-dipoles gained over recent years, significant strides have been taken to design and develop new protocols that proceed efficiently under mild synthetic conditions and duly benefit from superior functional group tolerance and selectivity. In this review, we represent the current state of the art in this field and detailed methods for the synthesis of non-racemic pyrazolines and pyrazolidines via [3+2] metal and organocatalyzed transformations reported since the seminal work of Kobayashi et al. and Fu et al. in 2002 and 2003 up to the end of year 2017. Full article
(This article belongs to the Special Issue Pyrazole Derivatives)
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Open AccessReview Synthesis of Chromone-Related Pyrazole Compounds
Molecules 2017, 22(10), 1665; https://doi.org/10.3390/molecules22101665
Received: 28 August 2017 / Revised: 22 September 2017 / Accepted: 28 September 2017 / Published: 5 October 2017
Cited by 1 | PDF Full-text (25027 KB) | HTML Full-text | XML Full-text
Abstract
Chromones, six-membered oxygen heterocycles, and pyrazoles, five-membered two-adjacentnitrogen- containing heterocycles, represent two important classes of biologically active compounds. Certain derivatives of these scaffolds play an important role in medicinal chemistry and have been extensively used as versatile building blocks in organic synthesis. In
[...] Read more.
Chromones, six-membered oxygen heterocycles, and pyrazoles, five-membered two-adjacentnitrogen- containing heterocycles, represent two important classes of biologically active compounds. Certain derivatives of these scaffolds play an important role in medicinal chemistry and have been extensively used as versatile building blocks in organic synthesis. In this context, we will discuss the most relevant advances on the chemistry that involves both chromone and pyrazole rings. The methods reviewed include the synthesis of chromone-pyrazole dyads, synthesis of chromone-pyrazole-fused compounds, and chromones as starting materials in the synthesis of 3(5)-(2-hydroxyaryl)pyrazoles, among others. This review will cover the literature on the chromone and pyrazole dual chemistry and their outcomes in the 21st century. Full article
(This article belongs to the Special Issue Pyrazole Derivatives)
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