ChemInform Abstract: A New Aspect of the Pfitzinger Reaction: Microwave-Assisted Synthesis of the New Heterocyclic Ring System 6-Arylbenzo[4,5]imidazolo[2,1-b]quino[4,3-e]-1,3-thiazin-14-one.

ChemInform ◽  
2009 ◽  
Vol 40 (47) ◽  
Author(s):  
Hatem A. Abdel-Aziz ◽  
Sobhi M. Gomha
2009 ◽  
Vol 64 (7) ◽  
pp. 826-830 ◽  
Author(s):  
Hatem A. Abdel-Aziz ◽  
Sobhi M. Gomha

We report herein on the utility of the Pfitzinger reaction in a facile two-step synthesis of the new heterocyclic ring system 6-arylbenzo[4,5]imidazolo[2,1-b]quino[4,3-e]-1,3-thiazin-14-one using microwave irradiation (MWI) and/or conventional heating. Microwave irradiation was used for a rapid and efficient synthesis of quinoline-4-carboxylic acids 6a - d from the reaction of isatin with 2-(1Hbenzimidazol- 2-ylthio)-1-arylethanones 3a - d. Cyclization of cinchoninic acids 6a - d afforded the fused title compounds 7a - d.


2021 ◽  
Vol 08 ◽  
Author(s):  
Monika R. Tiwari ◽  
Navin B. Patel

Aims: The study aims to synthesize thiocoumarin scaffolds clubbed with pyrimidine and 1,3,4-oxadiazole ring system under microwave irradiation and describes their pharmacological activities. Background: We report herein a Lewis acid catalyzed efficient and simple procedure for synthesis of novel series of thiocoumarin clubbed with pyrimidine and 1,3,4-oxadiazole motifs under microwave irradiation. The microwave assisted technique has many advantages such as higher yield, a clean and selective procedure, shorter reaction time and simple work-up. Objective: The objective of the present study is to design and synthesize thiocoumarin scaffolds clubbed with pyrimidine and 1,3,4-oxadiazole ring system by microwave-assisted heating. Our prime focus is to highlight synthetic approach developed for the synthesis of heterocyclic moieties of pharmacological interest and the prominence has also been given to distinct advantages provided by microwave heating. Methods: Thiocoumarin clubbed with pyrimidine and 1,3,4-oxadiazole motifs was synthesized under microwave irradiation. All the synthesized molecules were evicted by IR, 1H NMR, 13C NMR and Mass spectra. The antimicrobial activity of synthesized compounds was examined against two Gram-negative bacteria (E. coli, P. aeruginosa), two Gram-positive bacteria (S. aureus, S. pyogenes) and three fungi (C. albicans, A. niger, A. clavatus) using the MIC (Minimal Inhibitory Concentration) method, anti-tubercular activity H37Rv using L. J. Slope Method and anti-oxidant activity using DPPH and ABTS bioassay method. Results: The application of microwave technology to rapid synthesis of biologically significant thiocoumarin analogues is very promising because of its shorter reaction time and higher yield. Some of these new derivatives showed moderate to good in-vitro anti-bacterial, anti-fungal and anti-tubercular activity. Compounds B4 and B7 appeared to have high radical scavenging efficacies as 35.32 ± 0.446 and 33.97 ± 1.069 μg/mL ± SD of IC50 values in DPPH and ABTS bioassay, respectively. Conclusion: Microwave assisted synthesis provides an implicit way to discover promising class of molecular entities for the development of new anti-microbial and anti-oxidant agents. Oxadiazole and Pyrimidine bearing Thiocoumarin derivatives showed improved anti-microbial, anti-tubercular and anti-oxidant activity.


2012 ◽  
Vol 9 (1) ◽  
pp. 55-62
Author(s):  
Nguyen Dinh Thanh

Some peracetylated glucopyranosyl thioureas containing a heterocyclic ring system, benzo-1,3-thiazole have been prepared by the condensation reaction of tetra-O-acetyl-β-D-glucopyranosyl isothiocyanate and corresponding substituted 2-amino-(6-substituted)benzo-1,3-thiazoles. Investigated heating conditions showed that the solventless microwave-assisted method gave higher yields of these thioureas.


2020 ◽  
Author(s):  
Marat Korsik ◽  
Edwin Tse ◽  
David Smith ◽  
William Lewis ◽  
Peter J. Rutledge ◽  
...  

<p></p><p>We have discovered and studied a <i>tele</i>substitution reaction in a biologically important heterocyclic ring system. Conditions that favour the <i>tele</i>-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 crystallography 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 <i>in vivo </i>active anti-plasmodium compounds of Series 4 of the Open Source Malaria consortium.</p> <p> </p> <p>Archive of the electronic laboratory notebook with the description of all conducted experiments and raw NMR data could be accessed via following link <a href="https://ses.library.usyd.edu.au/handle/2123/21890">https://ses.library.usyd.edu.au/handle/2123/21890</a> . For navigation between entries of laboratory notebook please use file "Strings for compounds in the article.pdf" that works as a reference between article codes and notebook codes, also this file contain SMILES for these compounds. </p><br><p></p>


2020 ◽  
Vol 57 (3) ◽  
pp. 265-272
Author(s):  
Priya S. Singh ◽  
Aizaz Shaikh ◽  
Aditi Deshmukh ◽  
Amit P. Pratap

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