Synthesis and solvatochromic properties of some disazo dyes derived from pyrazolo[1,5-a]pyrimidine derivatives

Tsai, Pi Chen; Wang, Ing Jing

doi:10.1016/j.dyepig.2004.05.013

Cited by 63 publications

(6 citation statements)

References 11 publications

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“…For example, the hypnotic drug Indiplon ( I ), diamide derivative ( II ) (good anticancer activity), and anxiolytic agent Ocinaplon ( III ) have this structural scaffold 7-aryl substituted as well as diverse carbonyl derivatives at position 3 (Figure ). In addition, pyrazolo[1,5- a ]pyrimidines (PPs) have found applications in material sciences because of their interesting photophysical properties …”

Section: Introductionmentioning

confidence: 99%

3-Formylpyrazolo[1,5-a]pyrimidines as Key Intermediates for the Preparation of Functional Fluorophores

2018

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A one-pot route for the regioselective synthesis of 3-formylpyrazolo[1,5- a]pyrimidines 4a-k in good yields through a microwave-assisted process is provided. The synthesis proceeds via a cyclocondensation reaction between β-enaminones 1 with NH-3-aminopyrazoles 2, followed by formylation with an iminium salt moiety (Vilsmeyer-Haack reagent). These N-heteroaryl aldehydes 4 were successfully used as strategic intermediates for the preparation of novel functional fluorophores with yields up to 98%. The structures of the products obtained and regioselectivity of the reactions were determined on the basis of NMR measurements and X-ray diffraction analysis. Since pyrazolo[1,5- a]pyrimidines (PPs) 3 have shown an important fluorescence, photophysical properties of four 2-methylderivatives substituted at position 7 with different acceptor (A) or donor (D) groups were investigated. The compounds evaluated exhibited large Stokes shift in different solvents, but only the substituted p-methoxyphenyl (4-An) showed a strong fluorescence intensity with quantum yields up to 44% due to its greater ICT. Therefore, hybrid systems based on pyrazolo[1,5- a]pyrimidines could be used as fluorescent probes to detect biologically or environmentally relevant species.

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Section: Introductionmentioning

confidence: 99%

3-Formylpyrazolo[1,5-a]pyrimidines as Key Intermediates for the Preparation of Functional Fluorophores

2018

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“…Moreover, the reaction of 2a with acrylonitrile was investigated as a possible route for the synthesis of pyrazolo[1,5-a]pyrimidines. Compound 2a, treated with acrylonitrile in boiling pyridine, afforded directly the iminopyrazolo[1,5-a]pyrimidine (6) and not the cyano ethylation product (5). Compound 6 could be readily converted to the corresponding 5-ketopyrazolo[1,5a]pyrimidine derivative (7) by refluxing it in a mixture of acetic acid-hydrochloric acid or by heating with conc.…”

Section: Scheme 1 Synthesis Of Pyrazole Derivativesmentioning

confidence: 99%

“…3,4 5-Aminopyrazoles are very important class of heterocycles due to their biological and pharmacological activities. 5,6 These compounds often exhibit antiinflammatory, herbicidal, fungicidal, bactericidal, and antipyretic activities. [6][7][8][9][10][11][12] The aminopyrazole compounds have been easily obtained by the reaction of nitrile derivatives with hydrazine, and are very useful as precursors for the synthesis of fused heterocyclic ring systems.…”

Section: Introductionmentioning

confidence: 99%

SYNTHESIS OF SOME NEW HETEROARYLBISAZO DYES DERIVED FROM p-AMINOAZOBENZENE

Ameen¹,

Fadda²

2018

ECB

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Several novel arylbisazopyrazolo[1,5-a]pyrimidines were synthesized from diazotization of 4-aminoazobenzene and coupling with malononitrile and then refluxed with hydrazine hydrate to give 3,5-diamino-4-arylbisazo-1H-pyrazole.The later compound was diazotized and coupled with bifunctional reagents to produce novel heteroarylbisazo dyestuffs. Structural characterization of these novel dyes was carried out using IR, 1 H NMR, and mass spectroscopy.

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“…Pyrazoles exist in many compounds that are used as pharmaceuticals and agrochemicals [5]. Fused pyrazoles have fungicidal [6], herbicidal [7], veridical [8] and insecticidal activity [9] [10] and have been used for the treatment of rheumatoid arthritis [11] [12]. Beside the pharmaceutical importance pyrazoles are very important class of heterocycles due to their commercial uses in dyestuffs and food coloring agents [13].…”

Section: Introductionmentioning

confidence: 99%

An Eco-Friendly Synthesis of Heterocyclic Moieties Condensed with Pyrazole System under Green Conditions and Their Biological Activity

El‐Borai¹,

Rizk²,

Sadek³

et al. 2016

GSC

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The efficient, facile and green synthesis of 4-bromo pyrazolone by using N-bromo saccharine as valuable green reagent encouraged us to prepare some new fused heterocycles as furopyrazole, pyranopyrazole, imidazopyrazole, pyrazolothiazole, pyrazol thiazolopyrimidine, pyrazolothiazine, oxathinopyrazole, pyrazolobenzooxazine, and pyrazoloquinoxaline. The synthesis was carried out by a basic condensation of bromo pyrazolone 2 and a suitable reagent in a one-pot reaction using chitosan as a green basic catalyst. The reactions were carried out by microwave irradiation technique as a green source of energy as well as the conventional heating. The antioxidant activity of the prepared compounds was studied using 1,1-phenyl-2-picrylhydrazyl (DPPH) assay and their antibacterial activity against Gram-positive, Gram-negative bacteria and antifungal activity was evaluated.

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Synthesis and solvatochromic properties of some disazo dyes derived from pyrazolo[1,5-a]pyrimidine derivatives

Cited by 63 publications

References 11 publications

3-Formylpyrazolo[1,5-a]pyrimidines as Key Intermediates for the Preparation of Functional Fluorophores

3-Formylpyrazolo[1,5-a]pyrimidines as Key Intermediates for the Preparation of Functional Fluorophores

SYNTHESIS OF SOME NEW HETEROARYLBISAZO DYES DERIVED FROM p-AMINOAZOBENZENE

An Eco-Friendly Synthesis of Heterocyclic Moieties Condensed with Pyrazole System under Green Conditions and Their Biological Activity

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