Reactions with heterocyclic amidines: Synthesis of several new pyrazolo[1,5-a]pyrimidines and pyrazolo[1,5-a][1,3,5]triazines

Abbas-Temirek, Husien Hasan; Abo‐Bakr, Ahmed M.

doi:10.5155/eurjchem.7.1.107-114.1369

Cited by 6 publications

(3 citation statements)

References 26 publications

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“…Bakr et al [ 153 ] reported the synthesis of pyrazolo[1,5- a ][1,3,5]triazine-8-carboxylic acid ethyl ester 244 from the reaction of aminopyrazolylurea derivative 242 and N -bis(methylthio)methylenecyanamide ( 243 ) out in DMF in presence of potassium carbonate ( Scheme 66 ).…”

Section: Reviewmentioning

confidence: 99%

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

Aggarwal

Kumar

2018

Beilstein J. Org. Chem.

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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. ReviewPyrazole and its derivatives are known to exhibit significant biological and pharmacological activities such as: anticancer [1,2], anti-inflammatory [3,4], antioxidant [5], antibacterial [6][7][8], analgesic [9], antiviral [10,11], antimicrobial [12,13], antifungal [6], antiglycemic [14], antiamoebic [15] and antidepressive [16,17]. Considering the immense biological properties pyrazole is one of the most widely studied nitrogen-containing heterocyclic nuclei. Fused pyrazole derivatives are composed of the pyrazole nucleus attached to other heterocyclic moieties which enable them to exhibit improved pharmacological activities compared to the isolated fragments. These compounds are currently used in several marketed drugs like cartazolate (1), zaleplon (2), sildenafil (3), allopurinol (4), indiplon (5), etazolate (6) etc. (Figure 1). Fused pyrazole derivatives, especially pyrazoloazines have been reported to mimic purine bases, present in DNA and RNA, due to close structural resemblance.In addition to the immense biological potential related to fused pyrazoles, their synthetic potential needs to be reviewed for further improvements and extension of interests. Various efforts have been developed for the synthesis of pyrazole-based fused heterocycles. 5-Aminopyrazoles have been extensively employed as useful synthons in designing and constructing a Beilstein J. Org. Chem. 2018, 14, 203-242. 204 A number of review articles have been published by us and others highlighting the synthetic and biological aspects of 5-aminopyrazoles [26][27][28] as well as on the synthesis of fused pyrazole derivatives [25]. However, a perusal of literature reveals that the importance of 5-aminopyrazoles as synthetic precursors for fused heterocycles has not been reported till now to the best of our knowledge. Recent literature shows resurgence of interest in the chemistry and bioactivity of 5-aminopyrazole derivatives leading to improvements in several already known reactions and syntheses of various fused heterocyclic derivatives with various biological activities. Considering the synthetic importance of 5-aminopyrazoles and synthesis of fused pyrazole derivatives with the need for a more general collection, herein we report an exhaustive overview of the main developments in the last decade in the chemistry of 5-aminopyrazoles for the design and synthesis of fused pyrazoloazines.The typical reactivity of 5-aminopyrazoles 5-Aminopyrazoles are polyfunctional co...

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Section: Reviewmentioning

confidence: 99%

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

Aggarwal

Kumar

2018

Beilstein J. Org. Chem.

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“…[5][6][7][8] have reported that while 4-arylazopyrazole-3,5-diamines react with acrylonitrile and ethyl acrylate (5a,b) to yield 4-(3,5-diamino)-4-(phenyldiazenyl)-1H-pyrazol-1-yl)butanenitrile or ethyl(3,5-diamino-4-(phenyl diazenyl)-1H-pyrazol-1-yl)butanoate (6a,b) that could be cyclized into 2-amino-3-(phenyldiazenyl)pyrazolo [1,5-a]pyrimidin-5(4H)-one (7) upon reflux in AcOH (Scheme 1). Similarly, 4-arylazopyrazole-3,5-diamines reacted with phenyl isothiocyanate (8) to afford 3,5-diamino-N-phenyl-4-(phenyl diazenyl)-1H-pyrazole-1-carbothioamide (9). Attempted cyclisation of compound 9 via refluxing in AcOH afforded the N,N'(4-phenyldiazenyl)-1H-pyrazole-3,5-diyl)diacetamide (10).…”

Section: -Arylazopyrazole-35-diamines (4) First Synthesized Bymentioning

confidence: 99%

“…Because of potential utility of the chemistry in Scheme 1 in fine chemical industry it looked of value to optimize reaction conditions and confirmed concluded structures as only few pyrazolo [1,5-a]pyrimidine derivatives have been reported in the literature [9][10][11][12][13][14][15][16][17]. Although several pyrazolopyrimidine-7ones have been synthesized and tested for a variety of activities, only few isomeric-5-ones have ever been synthesized.…”

Section: -Arylazopyrazole-35-diamines (4) First Synthesized Bymentioning

confidence: 99%

Pressure as effective green technology for synthesis of polyfunctionally substituted heteroaromatics: Synthesis of a variety of pyrazolo[1,5-a]pyrimidines

et al. 2016

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Pyrazole molecules are in the forefront of organic chemistry due to their various encompass substituents, which have many biological activity sequence. The biological and medicinal activities of pyrazolo[1,5-a]pyrimidines have received considerable interest in this regard. We reported here a comparison between reaction of 4-phenylazo-3,5-diaminopyrazole (4) with ethyl propiolate (15), dimethylacetylene dicarboxylate (20), diethyl fumarate (25) and benzylidenemalononitrile (11) in the presence of catalytic amount of piperidine. We initially followed literature procedure (method A), then utilizing ultrasound irradiation (method B), microwave heating (method C) and in a Q-tube (method D). We confirmed the structure of the product by analytical spectroscopic methods. Method (D) gave a good yield with a record reaction time. KEYWORDS Q-tube High yields Record time Green technology Pyrazolo[1,5-a]pyrimidines Reactions under increased pressure

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Efficient One Pot and Chemoselective Synthesis of Polysubstituted Dihydro‐6H‐chromeno[4,3‐d]pyrazolo[1,5‐a]pyrimidin‐6‐ones via a Four‐Component Reaction

Alizadeh

Rostampoor

2022

ChemistrySelect

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In this research, a simple and chemoselective synthesis of highly fluorescent polysubstituted dihydro‐6H‐chromeno[4,3‐d]pyrazolo[1,5‐a]pyrimidin‐6‐ones containing one chiral stereocenter is presented by a sequential four‐component reaction of 4‐chloro‐3‐formylcoumarin, 1‐phenyl‐2‐(1,1,1‐triphenyl‐λ5‐phosphanylidene)ethan‐1‐ones (Wittig reagent), benzoylacetonitriles and hydrazine hydrate as readily available starting materials, which includes base‐mediated 1,4‐addition/aza‐Michael addition/formation of two C−N bonds. The desired products were obtained with short reaction times, easy purification (products can be purified by washing with EtOH), and medium to high yields (up to 92 %) under relatively mild reaction conditions. Molecular structures were determined by IR spectrophotometry, mass spectrometry, NMR spectroscopy, and single‐crystal X‐ray analysis.

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Reactions with heterocyclic amidines: Synthesis of several new pyrazolo[1,5-a]pyrimidines and pyrazolo[1,5-a][1,3,5]triazines

Abstract: N-Bis(methylt malononitrile derivatives (3 aminopyrazol carboxylic aci pyrazolopyrim synthesized c 1 H 13 C NMR an

Cited by 6 publications

References 26 publications

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

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

Pressure as effective green technology for synthesis of polyfunctionally substituted heteroaromatics: Synthesis of a variety of pyrazolo[1,5-a]pyrimidines

Efficient One Pot and Chemoselective Synthesis of Polysubstituted Dihydro‐6H‐chromeno[4,3‐d]pyrazolo[1,5‐a]pyrimidin‐6‐ones via a Four‐Component Reaction

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