scholarly journals Microwave-assisted multi-component synthesis of 3’-indolyl substituted pyrano[2,3-c]pyrazoles and their antimicrobial activity

2012 ◽  
Vol 77 (8) ◽  
pp. 983-991 ◽  
Author(s):  
Harshad Kathrotiya ◽  
Ranjan Patel ◽  
Manish Patel

A series of pyrano[2,3-c]pyrazole derivatives of indole has been synthesized by multi-component reaction using conventional and microwave irradiation approach. Particularly valuable features of this method include high yield, broad substrate scope, shorter reaction time and straightforward procedure. Antimicrobial screening against eight human pathogens, namely B. subtilis, C. tetani, S. pneumoniae, S. typhi, V. cholerae, E. coli, A. fumigatus and C. albicans by employing broth microdilution MIC method as recommended by NCCLS.

2016 ◽  
Vol 19 (2) ◽  
pp. 64-70
Author(s):  
Phuong Hoang Tran ◽  
Vy Hieu Huynh ◽  
Hai Ngoc Tran ◽  
Thach Ngoc Le

Intramolecular Friedel–Crafts acylation of aryl acids is a “green” reaction and environmentally benign, generates some valuable intermediated compounds for pharmaceutical uses. In addition, metal triflates under microwave irradiation are efficient catalysts, solving many problems when using traditional Lewis acids. Gd(OTf)3/[BMI]BF4, a good catalyst for the intramolecular Friedel–Crafts acylation under mild condition with high yield, reduced the reaction time and pollution. Furthermore, Gd(OTf)3 in [BMI]BF4 was easily recovered and reused without significant loss of its activity


2020 ◽  
Vol 16 (4) ◽  
pp. 481-488
Author(s):  
Heli Sanghvi ◽  
Satyendra Mishra

Background: Curcumin, one of the most important pharmacologically significant natural products, has gained significant consideration among scientists for decades since its multipharmacological activities. 1, 3-Dicarbonyl moiety of curcumin was found to be accountable for the rapid degradation of curcumin molecule. The aim of present work is to replace 1, 3-dicarbonyl moiety of curcumin by pyrazole and phenylpyrazole derivatives with a view to improving its stability and to investigate the role of substitution in N-phenylpyrazole curcumin on its antibacterial activity against both Gram-positive as well as Gram-negative bacteria. Methods: Pyrazole derivatives of curcumin were prepared by heating curcumin with phenyhydrazine/ substituted phenyhydrazine derivatives in AcOH. The residue was purified by silica gel column chromatography. Structures of purified compounds were confirmed by 1H NMR and Mass spectroscopy. The synthesized compounds were evaluated for their antibacterial activity by the microdilution broth susceptibility test method against gram positive (S. aureus) and gram negative (E. coli). Results: Effects of substitution in N-phenylpyrazole curcumin derivatives against S. aureus and E. coli were studied. The most active N-(3-Nitrophenylpyrazole) curcumin (12) exhibits twenty-fold more potency against S. aureus (MIC: 10μg/mL)) and N-(2-Fluoroophenylpyrazole) curcumin (5) fivefold more potency against E. coli (MIC; 50 μg/mL) than N-phenylpyrazole curcumin (4). Whereas, a remarkable decline in anti-bacterial activity against S. aureus and E. coli was observed when electron donating groups were incorporated in N-phenylpyrazole curcumin (4). Comparative studies of synthesized compounds suggest the effects of electron withdrawing and electron donating groups on unsubstituted phenylpyrazole curcumin (4). Conclusion: The structure-activity relationship (SAR) results indicated that the electron withdrawing and electron donating at N-phenylpyrazole curcumin played key roles for their bacterial inhibitory effects. The results of the antibacterial evaluation showed that the synthesized pyrazole derivatives of curcumin displayed moderate to very high activity in S. aureus. In conclusion, the series of novel curcumin derivatives were designed, synthesized and tested for their antibacterial activities against S. aureus and E. coli. Among them, N-(3-Nitrophenylpyrazole curcumin; 12) was most active against S. aureus (Gram-positive) and N-(2-Fluoroophenylpyrazole) curcumin (5) against E. coli (Gram-negative) bacteria.


2020 ◽  
Vol 7 (3) ◽  
pp. 183-195
Author(s):  
Musa Özil ◽  
Emre Menteşe

Background: Benzoxazole, containing a 1,3-oxazole system fused with a benzene ring, has a profound effect on medicinal chemistry research owing to its important pharmacological activities. On the other hand, the benzoxazole derivative has exhibited important properties in material science. Especially in recent years, microwave-assisted synthesis is a technique that can be used to increase diversity and quick research in modern chemistry. The utilization of microwave irradiation is beneficial for the synthesis of benzoxazole in recent years. In this focused review, we provide a metaanalysis of studies on benzoxazole in different reaction conditions, catalysts, and starting materials by microwave technique so far, which is different from conventional heating. Methods: Synthesis of different kind of benzoxazole derivatives have been carried out by microwave irradiation. The most used method to obtain benzoxazoles is the condensation of 2-aminophenol or its derivatives with aldehydes, carboxylic acids, nitriles, isocyanates, and aliphatic amines. Results: Benzoxazole system and its derivatives have exhibited a broad range of pharmacological properties. Thus, many scientists have remarked on the importance of the synthesis of different benzoxazole derivatives. Conventional heating is a relatively inefficient and slow method to convey energy in orientation to the reaction medium. However, the microwave-assisted heating technique is a more effective interior heating by straight coupling of microwave energy with the molecules. Conclusion: In this review, different studies were presented on the recent details accessible in the microwave- assisted techniques on the synthesis of the benzoxazole ring. It presents all examples of such compounds that have been reported from 1996 to the present. Benzoxazoles showed an extensive class of chemical substances not only in pharmaceutical chemistry but also in dyestuff, polymer industries, agrochemical, and optical brighteners. Thus the development of fast and efficient achievement of benzoxazoles with a diversity of substituents in high yield is getting more noteworthy. As shown in this review, microwave-assisted synthesis of benzoxazoles is a very effective and useful technique.


2011 ◽  
Vol 356-360 ◽  
pp. 277-282 ◽  
Author(s):  
Hsi Chi Yang ◽  
Jung Pin Wang ◽  
Chien Te Hsieh

This article reports a microwave-assisted route to synthesize nanosilver colloidal suspension and to deposit silver nanoparticles onto activated carbon fabrics (ACFs). The properties of the nanosilver suspension are characterized in terms of bacterial inactivation and growth inhibition. The metallic Ag nanocrystals with narrow size distribution are uniformly dispersed onto ACFs under the microwave irradiation of 1 min. Microwave irradiation is capable of heating up the reaction solution homogeneously, inducing uniform nucleation and rapid crystal growth to form the Ag crystallites. This work aims to elucidate how as-grown Ag nanoparticles affect the inactivation of Escherchia coli (E. coli) and how Ag-ACF surface inhibits the bacterial growth. The Ag colloidal suspension offers superior anti-bacterial ability against E. coli cells at a low concentration of 20 mg/L. Thus, the study has established a simple, efficient and effective process in the synthesis of both Ag colloidal suspension and Ag-ACF composite.


2019 ◽  
Vol 31 (5) ◽  
pp. 993-996 ◽  
Author(s):  
Sanjay S. Kotalwar ◽  
Amol D. Kale ◽  
Ram B. Kohire ◽  
Vasant B. Jagrut

An efficient and eco-friendly synthesis of 1,5-benzothiazepines has been developed by the reaction of various 2-propen-1-ones with 2-aminothiophenol using microwave irradiation in greener reaction medium, glycerol. The clean reaction conditions, shorter reaction time, high yields and non-toxic, biodegradable reaction medium manufactured from renewable sources are unique features of this method.


2019 ◽  
Vol 31 (4) ◽  
pp. 829-833
Author(s):  
D.S. Bhagat ◽  
S.G. Pande ◽  
M.V. Katariya ◽  
R.P. Pawar ◽  
P.S. Kendrekar

One-pot efficient protocol to the synthesis of 2-amino-5-oxo-4,5-dihydropyrano(3,2-c)chromene-3-carbonitrile derivatives via condensation of various aryl aldehydes, dicyanomethane and 4-hydroxycoumarin in presence of Emim hydroxide as an excellent homogeneous liquid catalyst. The key advantages of this methodology are mild reaction conditions, novel catalyst, short reaction time, eco-friendly, easy work-up procedure and high yield of isolation of derivatives.


2020 ◽  
Vol 7 (1) ◽  
pp. 60-66
Author(s):  
Navin B. Patel ◽  
Rahul B. Parmar ◽  
Hetal I. Soni

Background: A Lewis acid promoted efficient and facile procedure for one-pot synthesis of a novel series of fluoroquinolone clubbed with thiadiazoles motifs under microwave irradiation is described here. This technique has more advantages such as high yield, a clean procedure, low reaction time, simple work-up and use of Lewis acid catalyst. Objective: Our aim is to generate a biologically active 1,3,4- thiadiazole ring system by using a onepot synthesis method and microwave-assisted heating. High yield and low reaction time were the main purposes to synthesize bioactive fluoroquinolone clubbed 1,3,4- thiadiazole moiety. Methods: Fluoroquinolone Clubbed 1,3,4-Thiadiazole Motifs was prepared by Lewis acid promoted, one-pot synthesis, under microwave irradiation. All the synthesized molecules were determined by IR, 1H NMR, 13C NMR, and Mass spectra. The antimicrobial activity of synthesized compounds was examined against two Gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa), two Gram-positive bacteria (Staphylococcus aureus, Streptococcus pyogenes), and three fungi (Candida albicans, Aspergillus niger, Aspergillus clavatus) using the MIC (Minimal Inhibitory Concentration) method and antitubercular activity H37Rv using L. J. Slope Method. Results: Lewis acid promoted, one-pot synthesis of Fluoroquinolone clubbed 1,3,4-Thiadiazole motifs under microwave irradiation is an extremely beneficial method because of its low reaction time and good yield. Some of these novel derivatives showed moderate to good in vitro antibacterial, antifungal, and antitubercular activity. Conclusion: One-pot synthesis of 1,3,4-Thiadiazole by using Lewis acid catalyst gives a good result for saving time and also getting more production of novel heterocyclic compounds with good antimicrobial properties via microwave heating method.


2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Feray Aydogan ◽  
Cigdem Yolacan

A new procedure to synthesize the N-substituted pyrrole derivatives by Clauson Kaas reaction catalyzed by acidic ionic liquid under microwave irradiation was developed. This procedure provides several advantages such as high yield, clean product formation, and short reaction time.


2006 ◽  
Vol 84 (5) ◽  
pp. 819-824 ◽  
Author(s):  
Guirong Qu ◽  
Suhui Han ◽  
Zhiguang Zhang ◽  
Mingwei Geng ◽  
Feng Xue

An efficient and green procedure for the synthesis of purine acyclic nucleosides through microwave-assisted alkylation of various purine nucleobases with 2-oxa-1,4-butanediol diacetate in the absence of solvent and catalyst is described. The advantages of using this method include its environmental friendliness, simple manipulation, short reaction time, high regioselectivity, and good yields.Key words: acyclic nucleosides, microwave irradiation, regioselectivity, alkylation, 2-oxa-1,4-butanediol diacetate.


2011 ◽  
Vol 9 (4) ◽  
pp. 635-647 ◽  
Author(s):  
Chetan Sangani ◽  
Divyesh Mungra ◽  
Manish Patel ◽  
Ranjan Patel

AbstractA new series of twenty four derivatives of pyrano[3,2-c]chromene IVa-x bearing 1H-pyrazole were synthesized by a one pot, base-catalyzed cyclocondensation reaction of 1H-pyrazole-4-carbaldehyde Ia-l, malononitrile II and 4-hydroxycoumarin IIIa-b. All the synthesized compounds were characterized by elemental analysis, FT-IR, 1H NMR and 13C NMR spectral data. All the synthesized compounds were screened against six bacterial pathogens, namely B. subtilis, C. tetani, S. pneumoniae, S. typhi, V. cholerae, E. coli and for antifungal activity against two fungal pathogens, A. fumigatus and C. albicans using the broth microdilution MIC method. Some of the compounds were found to be equipotent or more potent than commercial drugs against most of employed strains, as evident from the screening data.


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