5-Aminopyrazole as precursor in design and synthesis of fused pyrazoloazines

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Abstract

The condensation of 5-aminopyrazole with various bielectrophilic moieties results in the formation of pyrazoloazines, an interesting array of fused heterocyclic systems. The development of new synthetic routes towards pyrazoloazines for their biological and medicinal exploration is an attractive area for researchers throughout the world. The present review focuses on various synthetic methods developed in the last decade for the synthesis of differently substituted pyrazoloazines by a broad range of organic reactions by means of 5-aminopyrazole as a precursor.

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Monoamine oxidase: isoforms and inhibitors in Parkinson's disease and depressive illness.

M. B. H. Youdim, Y Bakhle (2005)

A few years after the foundation of the British Pharmacological Society, monoamine oxidase (MAO) was recognized as an enzyme of crucial interest to pharmacologists because it catalyzed the major inactivation pathway for the catecholamine neurotransmitters, noradrenaline, adrenaline and dopamine (and, later, 5-hydroxytryptamine, as well). Within the next decade, the therapeutic value of inhibitors of MAO in the treatment of depressive illness was established. Although this first clinical use exposed serious side effects, pharmacological interest in, and investigation of, MAO continued, resulting in the characterization of two isoforms, MAO-A and -B, and isoform-selective inhibitors. Selective inhibitors of MAO-B have found a therapeutic role in the treatment of Parkinson's disease and further developments have provided reversible inhibitors of MAO-A, which offer antidepressant activity without the serious side effects of the earlier inhibitors. Clinical observation and subsequent pharmacological analysis have also generated the concept of neuroprotection, reflecting the possibility of slowing, halting and maybe reversing, neurodegeneration in Parkinson's or Alzheimer's diseases. Increased levels of oxidative stress in the brain may be critical for the initiation and progress of neurodegeneration and selective inhibition of brain MAO could contribute importantly to lowering such stress. There are complex interactions between free iron levels in brain and MAO, which may have practical outcomes for depressive disorders. These aspects of MAO and its inhibition and some indication of how this important area of pharmacology and therapeutics might develop in the future are summarized in this review.

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Synthesis and antiviral activity of new pyrazole and thiazole derivatives.

Osama El-Sabbagh, Mohamed M. Baraka, Samy M Ibrahim … (2009)

New N-acetyl (5-8) and N-thiocarbamoyl (9-12) derivatives of 4,5-dihydropyrazole were synthesized starting from alpha,beta-unsaturated ketones under the effect of hydrazine hydrate and thiosemicarbazide, respectively. N-Thiocarbamoylpyrazole derivatives (9-12) were cyclized using either ethyl bromoacetate or phenacyl bromides to afford the novel pyrazolothiazol-4(5H)-ones (13-16) or pyrazolothiazoles (17-24). The antiviral activity for such novel compounds against a broad panel of viruses in different cell cultures revealed that N-acetyl 4,5-dihydropyrazole 7 was the only active one at subtoxic concentrations against vaccinia virus (Lederle strain) in HEL cell cultures with a 50% effective concentration (EC(50)) value of 7 microg/ml.

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Synthesis and biological evaluation of some thiazolyl and thiadiazolyl derivatives of 1H-pyrazole as anti-inflammatory antimicrobial agents.

Adnan A Bekhit, Hayam M A Ashour, Yasser S Abdel Ghany … (2008)

Four series of pyrazolyl benzenesulfonamide derivatives have been synthesized. The first series was prepared by cyclization of the intermediate N,N-dimethylaminomethylene-4[3-phenyl-4-(substituted thiosemicarbamoyl hydrazonomethyl)-1H-pyrazol-1-yl]benzenesulfonamide 2a-c with ethyl bromoacetate to afford the corresponding thiazolidinyl derivatives 3a-c. The second series was prepared by cyclization of the key intermediates 2a-c with 4-bromophenacyl bromide giving rise to thiazolinyl derivatives 4a-c. Thiadiazolyl derivatives 5a-c were obtained by heating 2a-c with 2M FeCl(3) solution. Refluxing the intermediates 2a-c in acetic anhydride yielded the corresponding thiadiazolinyl derivatives 6a-c. All the target compounds showed anti-inflammatory activity and three of them 3b, 3c and 4c surpassed that of indomethacin both locally and systemically in the cotton pellet granuloma and rat paw edema bioassay. The active compounds showed selective inhibitory activity towards COX-2 enzyme as revealed by the in vitro enzymatic assay. All the tested compounds proved to have superior gastrointestinal (GI) safety profiles as compared to indomethacin, when tested for their ulcerogenic effects. The acute toxicity study of compounds having promising anti-inflammatory activity (3b, 3c and 4c) indicated that they are well tolerated both orally and parenterally. Antimicrobial activity tests expressed as minimal inhibitory concentrations (MIC), revealed that compounds 3b and 4a showed comparable antibacterial activity to that of ampicillin against Escherichia coli, while compounds 3a, 3c and 4a possessed about half the activity of ampicillin against Staphylococcus aureus. On the other hand, the results showed that all the tested compounds have weak or no antifungal activity against Candida albicans except for compounds 6b and 6c that showed half the activity of the control antifungal drug used (clotrimazole).

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Author and article information

Contributors

Ranjana Aggarwal

Suresh Kumar

Jeffrey Aubé: Role: Associate Editor

Journal

Journal ID (nlm-ta): Beilstein J Org Chem

Journal ID (iso-abbrev): Beilstein J Org Chem

Title: Beilstein Journal of Organic Chemistry

Publisher: Beilstein-Institut (Trakehner Str. 7-9, 60487 Frankfurt am Main, Germany )

ISSN (Electronic): 1860-5397

Publication date Collection: 2018

Publication date (Electronic): 25 January 2018

Volume: 14

Pages: 203-242

Affiliations

[1 ]Department of Chemistry, Kurukshetra University, Kurukshetra-136119, Haryana, India

Article

DOI: 10.3762/bjoc.14.15

PMC ID: 5789427

SO-VID: e2903cdc-b7bb-4df8-b914-a547701f33d8

License:

This is an Open Access article under the terms of the Creative Commons Attribution License ( http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

The license is subject to the Beilstein Journal of Organic Chemistry terms and conditions: (https://www.beilstein-journals.org/bjoc)

History

Date received : 14 July 2017

Date accepted : 8 January 2018

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5-Aminopyrazole as precursor in design and synthesis of fused pyrazoloazines

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Most cited references 167

Monoamine oxidase: isoforms and inhibitors in Parkinson's disease and depressive illness.

Synthesis and antiviral activity of new pyrazole and thiazole derivatives.

Synthesis and biological evaluation of some thiazolyl and thiadiazolyl derivatives of 1H-pyrazole as anti-inflammatory antimicrobial agents.

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Cited by 8

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