microwave irradiation
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Molecules ◽  
2022 ◽  
Vol 27 (2) ◽  
pp. 525
Claudia Feberero ◽  
Cintia Virumbrales ◽  
Carlos Sedano ◽  
Lorena Renedo ◽  
Samuel Suárez-Pantiga ◽  

A straightforward and transition metal-free one-pot protocol to synthesize halobenzo[b]furans has been developed employing simple and easily available starting materials such as O-aryl carbamates and alkynylsulfones. The fine-tuning of the different steps involved was key to achieving a successful one-pot procedure. Initially, a directed ortho-lithiation process, which uses the carbamate as the directed metalation group, was crucial in providing access to O-2-alkynylaryl N,N-diethyl carbamates by a direct alkynylation of the o-lithiated carbamate, with arylsulfonylalkynes as electrophilic reagents. Cyclization of the generated o-alkynylaryl carbamates was successfully accomplished through a strategy involving in situ carbamate alkaline hydrolysis under conventional heating or microwave irradiation, coupled with a subsequent heterocyclization step delivering the desired benzo[b]furans. A wide variety of new halobenzo[b]furans has been synthesized and their utility has been demonstrated by their further transformation.

Foods ◽  
2022 ◽  
Vol 11 (2) ◽  
pp. 221
Eva Popelářová ◽  
Eva Vlková ◽  
Roman Švejstil ◽  
Lenka Kouřimská

Microwave (MW) irradiation is a non-destructive method that can be applied as an alternative method to inhibit the growth of microorganisms. The present study evaluated the effect of MW irradiation on the occurrence of moulds in nuts and almonds. Samples of unshelled natural almonds, pistachios, and in-shell peanuts were treated with different doses of MW irradiation (2400–4000 W). The effect of MW irradiation on mould counts was evaluated by cultivating immediately after irradiation and after 3 and 6 months of storage. The most represented genera in all analysed samples were Aspergillus (68%), Penicillium (21%), and a small amount of Cladosporium (3%). Mould numbers significantly decreased after MW treatment. The treatments with MW irradiations at 3000 and 4000 W significantly reduced the mould colony counts, and their effect persisted during storage; irradiation at 2400 W was partially effective. The strongest effect of MW irradiation was observed in in-shell peanuts. MW irradiation seems to be a promising method for maintaining the microbiological quality of nuts.

2022 ◽  
Vol 7 (1) ◽  
pp. 115-121
Katarína Kráľová ◽  
Renata Gašparová ◽  
Martin Moncman

A new series of carboxhydrazides 6-8 was synthesized under microwave irradiation by reaction of carboxhydrazide 1 with heterocyclic aldehydes 2-4 in the presence of p-toluenesulfonic acid in ethanol. N-Benzoylcarboxhydrazide 9 was prepared by reaction of 1 with benzoylchlorid 5 in THF at room temperature. The effects of 6-9 on inhibition of photosynthetic electron transport in spinach chloroplasts and chlorophyll content in the antialgal suspensions of Chlorella vulgaris were investigated.

2022 ◽  
Vol 19 ◽  
Hetal I. Soni ◽  
Navin B. Patel ◽  
Rahul B. Parmar ◽  
Manuel J. Chan- Bacab ◽  
Gildardo River

Aim: This study aims to synthesize thiazolidine-4-one compounds with a pyrimidine nucleus and evaluate against different species of bacteria, fungi, protozoa, and the malaria parasite. Background: Microwave irradiation was the best method for synthesizing the thiazolidin-4-one ring system. It took only 15 minutes for synthesizing thiazolidin-4-one while the conventional method required 12 hours. The rapid reaction was the main concern of this research. Objective: Pyrimidine and Thiazolidin-4-one nucleus have broad-spectrum biological activity and when it is introduced with other hetero atoms containing moiety, many types of biological activities have been found; antimicrobial, anti-tuberculosis, anti-protozoa, antimalarial are the main activities. The activity of these compounds inspired us to do extra research on Thiazolidin-4-one fused pyrimidines with different functional groups. The aim of this is to synthesize a combination of these two ring systems in less time by using a microwave irradiation method and to evaluate new compounds for different bioactivity. Method: 2-(4-Chlorophenyl)-3-(4-(substituted phenyl)-6-(substituted aryl) pyrimidin-2-yl) thiazolidin-4-ones (6A-J) were synthesized by microwave irradiation to save energy and time. The structure of all newly synthesized motifs was characterized by spectral analysis (1H NMR, 13C NMR, IR, spectroscopy) and screened for antibacterial activity against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Streptococcus pyogenes, antifungal activity against Candida albicans, Aspergillus niger, Aspergillus clavatus, anti-tuberculosis activity against M. tuberculosis H37RV, antimalarial activity against Plasmodium falciparum and anti-protozoa activity against L. mexicana and T. cruzi. Result: Because of microwave irradiation synthesis, time period is very less for preparing the new compound. Biological response given by compounds 6B, 6C, 6D, 6E, 6G, 6H, and 6J was found excellent. Conclusion: Good yield with purity of the newly synthesized thiazolidine-4-one compounds obtained in less time by using microwave irradiation. The biological response of some of the compounds of this series was found excellent

2022 ◽  
Vol 24 (1) ◽  
pp. 34-47
Pankaj S. Kore ◽  
Santosh K. Singh ◽  
Shrinivas K. Mohite ◽  

The most of drugs containing Benzimidazole ring is a prominent structural motif found in numerous therapeutically active compounds. Benzimidazole and its synthetic analogues have been found to exhibit industrial, agricultural and biological application such as antitubercular, anti-inflammatory, analgesic, anticancer, anticoagulant, as well as good antifungal and anti microbial activity. Recent advances in technology considers microwave irradiation energy as the most efficient means of heating reactions for chemical transformations that can be accomplished in a minutes. Microwave irradiation assists organic synthesis (MAOS) not only helps in implementing green chemistry but also led to progress in organic synthesis. We report pharmacological screening of some novel 2 substituted and 1(h)-substituted Benzimidazole derivatives.

2022 ◽  
Vol 19 ◽  
Entesar A. Hassan ◽  
Salem E. Zayed ◽  
Al-Hassan S. Mahdy ◽  
Ahmed M. Abo-Bakr

Background: A series of new pyrimidines and thiazoles containing camphor moiety were synthesized under both conventional and microwave irradiation techniques. Methods: The condensation of camphor either with aminoguanidine or thiosemicarbazide gives the camphor hydrazine carboximidiamide 2 and the camphor thiosemicarbazone 3, respectively. Refluxing of 3 with chloroacetonitrile afforded the camphor thiazol-4-imine 4. Compounds 2 and 4 were used as precursors for the synthesis of target products. Results: The reaction of 2 with different species such as arylidene malononitrile, acetylacetone, and ethyl acetoacetate gave the corresponding camphor pyrimidine derivatives 5a,b-7 while refluxing of compound 4 with different reagents e.g. aldehydes, isatin, ninhydrin, acetic anhydride, benzene sulphonyl chloride, and p-nitro-benzoyl chloride afforded the camphor thiazole derivatives 8a-d-13, respectively. Conclusion: A comparison between the conventional way and the eco-friendly microwave irradiation method occurred in the synthesis of the same compounds, which the latter was more efficient. The elemental analysis, FT-IR, 1H NMR, 13C NMR, and Mass spectra confirm the structures of the obtained new compounds. The potential use of some selected derivatives as antimicrobial agents was investigated and gave promising results

2022 ◽  
Vol 6 (2) ◽  
pp. 84-87
Luthfi Ahmad Muchlashi

This study aims to compare conventional heating with microwave irradiation in order to obtain the optimal method for 3-amino-2-(2-chlorophenyl)quinazolin-4(3H)-one synthesis. For the compound to be completely synthesised, one needs to carry out much heating for a long period of time. 10 hours are required for the reaction using conventional heating; yet it takes only 5 minutes using microwave with 800 watts of power. It was found in this study that there was an improvement in percent yields of 3-amino-2-(2-chlorophenyl)quinazolin-4(3H)-one, 87 %  using microwave irradiation compared to 79 % using reflux. Therefore, microwave-assisted method is a quicker, higher yielding method for 3-amino-2-(2-chlorophenyl)quinazolin-4(3H)-one synthesis.

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