Facile one pot synthesis of 8-chloro-[1,2,4]triazolo[4,3-a]pyrazines via oxidative cyclisation using chloramine T

Mal, Sanjib; Prathap, K. Jagadeesh; Smith, Stephen C.; Umarye, Jayant D.

doi:10.1016/j.tetlet.2015.04.076

Cited by 15 publications

(11 citation statements)

References 22 publications

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“…[47][48][49][50] For optimization of the reaction conditions, initially the reaction in acetic acid in the presence of concentrated H 2 SO 4 as the catalyst afforded the desired product 7a in a 40% yield (entry 1), but this is a lower yield than reported in the literature. Then we tried using chloramine-T as the cyclizing reagent for the 1,3,4-oxadiazole synthesis, as reported in the literature; 51 in this case we also obtained a lower yield (entry 2). After further investigation of various catalysts, IBD was found to be more effective than other catalysts such as chloramine-T, lead dioxide and mercuric acetate, and the reaction yield increased up to 85% when IBD was employed (entries 3-9).…”

Section: Resultsmentioning

confidence: 87%

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Novel 1,3,4-oxadiazole motifs bearing a quinoline nucleus: synthesis, characterization and biological evaluation of their antimicrobial, antitubercular, antimalarial and cytotoxic activities

Ladani

Patel

2015

New J. Chem.

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A series of quinoline based 1,3,4-oxadiazole derivatives 8a-l were synthesized by chloro-amine coupling reaction approach with different catalyst and solvents. The substituted 1,3,4-oxadiazole intermediates 7a-c were obtained from 2-sustituted-N-phenylhydrazinecarbothioamide 6a-c by cyclization with different cyclizing reagents like mercuric acetate, lead dioxide, iodobenzenediacetate (IBD) and aqueous sodium hydroxide with iodine in aqueous potassium iodide to isolate the most effective reaction condition by using iodobenzenediacetate as extremely good catalyst. The structure of the title compounds were confirmed by FT-IR, 1 H NMR, 13 C NMR and mass spectrometry. The synthesized molecules were evaluated for their antibacterial, antifungal, antituberculosis and antimalarial activities. The brine shrimp bioassay was carried out to study the in vitro cytotoxic properties for the highly active compounds of in vitro biological evaluation. antifungal 34 . Quinoline scaffolds have been selected due to their diverse therapeutic and pharmacological properties, such as antitumor, antiatherosclerotic, vasodilator, geroprotective, bronchodilator and hepatoprotective activity 35 .

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Section: Resultsmentioning

confidence: 87%

“…Than we have tried to chloramine-T as cyclizing reagent for the 1,3,4-oxadiazole synthesis from literature 51 , in this case also we obtained lower yield (entry 2). But there is a lower yield than reported in literature.…”

Section: Cytotoxicity (Brine Shrimp Lethality Bioassay)mentioning

confidence: 81%

Novel 1,3,4-oxadiazole motifs bearing a quinoline nucleus: synthesis, characterization and biological evaluation of their antimicrobial, antitubercular, antimalarial and cytotoxic activities

Ladani

Patel

2015

New J. Chem.

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“…To better define the scope of tele -substitution in this triazolopyrazine system, 8- and 6-halogenated variants of the triazolopyrazine core were synthesized from the corresponding dihalopyrazines following literature procedures and subjected to the same reaction conditions as the original 5-chloro triazolopyrazine. The 8-halogenated cores ( 25 – 27 , Figure A) reacted to give the expected ipso -substituted products only ( 28 – 36 ), while the 6-halogenated analogues ( 37 and 38 , Figure B) resulted only in degradation of starting material without formation of any substituted product.…”

Section: Resultsmentioning

confidence: 99%

tele-Substitution Reactions in the Synthesis of a Promising Class of 1,2,4-Triazolo[4,3-a]pyrazine-Based Antimalarials

et al. 2020

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We have discovered and studied a telesubstitution reaction in a biologically important heterocyclic ring system. Conditions that favour the tele-substitution pathway were identified: the use of increased equivalents of the nucleophile or decreased equivalents of base, or the use of softer nucleophiles, less polar solvents and larger halogens on the electrophile. Using results from X-ray crystallographic and isotope labelling experiments, a mechanism for this unusual transformation is proposed. We focused on this triazolopyrazine as it is the core structure of the in vivo active anti-plasmodium compounds of Series 4 of the Open Source Malaria consortium.

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“…The proposed mechanism for the chloramine‐T trihydrate prompted oxidative transformation has been described in Scheme . In the initial step, aldehyde 2 condenses with 2‐hydrazinobenzothiazole ( 1 ) and forms the corresponding hydrazone 3 which then further reacts with chloramine‐T trihydrate to form the intermediate hydrazonylchloride 3‐I .…”

Section: Resultsmentioning

confidence: 99%

Chloramine‐T Mediated Facile One Pot Synthesis of Pyrazolyltriazolobenzothiazole Hybrids as Potent Anti‐Infective Agents

Kamal

Kumar

et al. 2019

ChemistrySelect

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An expedient and facile one pot synthesis of 3‐(3‐aryl‐1‐phenyl‐1H‐pyrazol‐4‐yl)‐[1,2,4]triazolo[3,4‐b]‐1,3‐benzothiazole derivatives through in situ oxidative cyclization of corresponding N‐heteroarylhydrazone promoted by environmentally benign chloramines‐T trihydrate at room temperature has been accomplished. Structures of all hybrids were confirmed by their spectral and elemental data. All synthesized pyrazolyltriazolobenzothiazole hybrids were also evaluated for their antibacterial and anthelmintic potential and were found to be moderate to significant anti‐infective agents.

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Facile one pot synthesis of 8-chloro-[1,2,4]triazolo[4,3-a]pyrazines via oxidative cyclisation using chloramine T

Cited by 15 publications

References 22 publications

Novel 1,3,4-oxadiazole motifs bearing a quinoline nucleus: synthesis, characterization and biological evaluation of their antimicrobial, antitubercular, antimalarial and cytotoxic activities

Novel 1,3,4-oxadiazole motifs bearing a quinoline nucleus: synthesis, characterization and biological evaluation of their antimicrobial, antitubercular, antimalarial and cytotoxic activities

tele-Substitution Reactions in the Synthesis of a Promising Class of 1,2,4-Triazolo[4,3-a]pyrazine-Based Antimalarials

Chloramine‐T Mediated Facile One Pot Synthesis of Pyrazolyltriazolobenzothiazole Hybrids as Potent Anti‐Infective Agents

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