A Facile Synthesis of Pyrazolo[3,4-b]pyridines

Ahluwalia, V. K.; Goyal, Bindu

doi:10.1080/00397919608003494

Cited by 34 publications

(31 citation statements)

References 4 publications

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“…Thus, the synthesis of the heterocyclic nucleus is of continuing interest. In view of the importance of polyhydroquinoline derivatives, many classical methods for their synthesis were reported [8][9][10][11][12][13] using conventional heating and refluxing approaches in the presence of an organic solvent. These methods, however, involves long reaction times, harsh reaction conditions, the use of a large quantity of volatile organic solvents and generally leading to low yields.…”

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confidence: 99%

An efficient one-pot synthesis of polyhydroquinoline derivatives via Hantzsch condensation using heterogeneous catalyst under solvent-free conditions

Maheswara¹,

Siddaiah²,

Damu³

et al. 2006

Arkivoc

140

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An efficient one-pot synthesis of polyhydroquinoline derivatives via Hantzsch condensation using heterogeneous catalyst under solvent-free conditions

Maheswara¹,

Siddaiah²,

Damu³

et al. 2006

Arkivoc

140

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“…The Friedländer condensation of o-amino aldehydes such as 5-aminopyrazole-4-carbaldehydes with ketones is described to take place either with strong bases or acids as catalysts; in special cases the ring closure can be observed without a catalyst at higher temperatures (e.g., under microwave irradiation) [34][35][36][37]. Having 5-aminopyrazolo-4-carbaldehyde in our hand, like others [4,[38][39][40][41] we have applied the Friedländer condensation reaction with active methylene compounds to get pyrazolo [3,4-b]pyridines. Initially we used piperidine [38] as the base for the condensation reaction, which unfortunately gave poor yield (< 20%).…”

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Synthesis and antibacterial activity of some novel pyrazolopyridine derivatives

Panda

Karmakar

Jena

2011

Chem Heterocycl Comp

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Eight pyrazolo [3,4-b]pyridine derivatives have been synthesized by Friedländer condensation of 5-aminopyrazole-4-carbaldehyde with active methylene compounds in basic medium. These compounds have been screened for their antibacterial activity against two Gram-negative and two Gram-positive bacterium. Pyrazolopyridines having the carboxamide group at the 5-position showed moderate to good activity against P. aeruginosa, E. coli, S. pneumoniae, and B. cereus.The evolution of antibacterial resistance in bacterial strains against the currently available antibacterial agents is an increasing concern in recent years. For instance, Gram-positive bacterial pathogen such as Staphylococcus aureus is resistant to Methicillin, and Streptococcus pneumoniae and Enterococci are resistant to Penicillin and Vancomycin, respectively [1]. On the other hand, Gram-negative bacteria such as H. influenza and M. catarrahalis are resistant to β-lactams, quinolones, and macrolides [2]. In order to overcome the threat of widespread multidrug resistance in Gram-positive as well as Gram-negative bacterial strains, there is an ongoing demand for new antibacterials.Pyrazolo [3,4-b]pyridines as aza-analogs of indazoles [3] have long served as attractive targets in organic synthesis due to their excellent antibacterial activity [4]. Moreover, pyrazolo[3,4-b]pyridines also exhibit other promising biological activities, including anxiolytic (e.g., Tracazolate) [5], dopamine D3-receptor antagonist and partial agonist [6], dopamine D4 antagonist [7], adenosine A1-receptor antagonist [8,9], antiherpetic [10], antiinflammatory [11], and antiallergic [12] properties. The methods so far reported for the synthesis of pyrazolopyridines include: i) the annelation of the pyrazole ring onto the suitably substituted pyridine ring [13][14][15][16][17][18][19], and ii) the annelation of the pyridine ring onto the appropriately substituted pyrazole ring [13,[20][21][22][23][24][25][26][27][28][29][30]. As part of our ongoing program [31] for the development of new antibacterials, we are particularly interested in the synthesis of pyrazolo [3,4-b]pyridines by the latter method. Like others, our strategy involves the Friedländer condensation of 5-aminopyrazoles with active methylene compounds as the key step. In this paper we report the full details of our efforts on the synthesis of some novel pyrazolo[3,4-b]pyridine derivatives and their antimicrobial profile against two Gram-positive and two Gram-negative bacterium species.

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“…In our other previous papers [10][11][12], pyrazolo [3,4-b]pyridines were synthesized by Friendlander condensation of 5-aminopyrazole-4-carbaldehyde with various reactive methylene compounds and the heterocyclic compounds with chloroethyl side chain [13]. In literature the pyrazolo [3,4-b]pyridines have been so far obtained by condensation of aminopyrazoles with , -unsaturated compounds [14][15][16][17][18], diethylethoxymethylenemalonate [19,20], active esters [21], cyclic ketones [11,12] and amides [12]. In the present paper, we have used the versatile cyclic -ketoester e.g.…”

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confidence: 99%