A Facile Microwave-Assisted Synthesis of Oxazoles and Diastereoselective Oxazolines Using Aryl-Aldehydes, p-Toluenesulfonylmethyl Isocyanide under Controlled Basic Conditions
Abstract:In this study, a highly efficient two-component [3 + 2] cycloaddition reaction of substituted aryl aldehydes with 4toluenesulfonylmethyl isocyanide (TosMIC) in the presence of 2 equiv of potassium phosphate as a base to 5-substituted oxazoles were established in a isopropanol medium under microwave irradiation. However, using 1 equiv of K 3 PO 4 as a base resulted in the diastereoselective synthesis of 4,5-disubstituted oxazolines under identical reaction conditions. The foremost benefits of these protocols ar… Show more
“…Mukku et al [42] selected substituted aryl aldehyde, TosMIC as a starting material and added 10 ml of isopropyl alcohol in a round-bottom flask, then charged with potassium phosphate as a catalyst. Then it was irradiated in an open vessel at 800 rpm at 65° and 350 W for 8 min.…”
Section: Microwave Assisted Synthesis Of Oxazole Derivativesmentioning
Green Synthetic Methods Synthesis of Oxazole DerivativesThis review compiles green synthetic methods intended for the synthesis of oxazole derivatives. Oxazoles are a class of compounds with a wide range of biological activities. The application and biological activity of oxazoles is highly dependent on their structure. Now-a-days, scientists have been performing the synthesis of oxazole derivatives. High demands in synthesis often result in the production of various hazardous chemical substances. So, to minimize the production of toxic chemical substances, green synthetic approaches are used in this manner. Green synthesis covers different synthetic approaches, including the application of microwave techniques, ultrasound, ionic liquids, deep-eutectic solvents, the use of catalysts and continuous flow synthesis. In this review, the authors mentioned that not only these green synthetic approaches reduce the formation and utilisation of toxic chemicals, but there is an increase in the reaction performance that enhances the product yields, purity, post-synthetic processes and energy consumption when compared to conventional methods. Due to the biological and pharmacological significance of oxazoles and the demands of decreasing toxic solvents, catalysts, and energy consumption, this article gives a full literature survey on the significance of green synthetic methods in oxazole synthesis. It contains a literature survey over the period from 2010-2020. The emphasis of this article is its comprehensive literature survey on oxazole, which is helpful for the researchers working on the oxazole scaffold and gaining information on the green synthetic approaches to their synthesis.
“…Mukku et al [42] selected substituted aryl aldehyde, TosMIC as a starting material and added 10 ml of isopropyl alcohol in a round-bottom flask, then charged with potassium phosphate as a catalyst. Then it was irradiated in an open vessel at 800 rpm at 65° and 350 W for 8 min.…”
Section: Microwave Assisted Synthesis Of Oxazole Derivativesmentioning
Green Synthetic Methods Synthesis of Oxazole DerivativesThis review compiles green synthetic methods intended for the synthesis of oxazole derivatives. Oxazoles are a class of compounds with a wide range of biological activities. The application and biological activity of oxazoles is highly dependent on their structure. Now-a-days, scientists have been performing the synthesis of oxazole derivatives. High demands in synthesis often result in the production of various hazardous chemical substances. So, to minimize the production of toxic chemical substances, green synthetic approaches are used in this manner. Green synthesis covers different synthetic approaches, including the application of microwave techniques, ultrasound, ionic liquids, deep-eutectic solvents, the use of catalysts and continuous flow synthesis. In this review, the authors mentioned that not only these green synthetic approaches reduce the formation and utilisation of toxic chemicals, but there is an increase in the reaction performance that enhances the product yields, purity, post-synthetic processes and energy consumption when compared to conventional methods. Due to the biological and pharmacological significance of oxazoles and the demands of decreasing toxic solvents, catalysts, and energy consumption, this article gives a full literature survey on the significance of green synthetic methods in oxazole synthesis. It contains a literature survey over the period from 2010-2020. The emphasis of this article is its comprehensive literature survey on oxazole, which is helpful for the researchers working on the oxazole scaffold and gaining information on the green synthetic approaches to their synthesis.
“…A characteristic example for the other methodologies is the reaction between benzaldehydes, with 4-phenyl-thiosemicarbazide involving a hydrazone intermediate which reacts with benzoin to obtain 2-oxazolines [28]; another methodology is based on the (3 + 2) reaction between TosMIC 5 and an aromatic aldehyde in the presence of a base. This synthetic strategy generally leads to the corresponding oxazole via the oxidation of the primary oxazoline formed [36][37][38].…”
The increase in multi-drug resistant Candida strains has caused a sharp rise in life-threatening fungal infections in immunosuppressed patients, including those with SARS-CoV-2. Novel antifungal drugs are needed to combat multi-drug-resistant yeasts. This study aimed to synthesize a new series of 2-oxazolines and evaluate the ligands in vitro for the inhibition of six Candida species and in silico for affinity to the CYP51 enzymes (obtained with molecular modeling and protein homology) of the same species. The 5-(1,3-diphenyl-1H-pyrazol-4-yl)-4-tosyl-4,5-dihydrooxazoles 6a-j were synthesized using the Van Leusen reaction between 1,3-diphenyl-4-formylpyrazoles 4a-j and TosMIC 5 in the presence of K2CO3 or KOH without heating, resulting in short reaction times, high compound purity, and high yields. The docking studies revealed good affinity for the active site of the CYP51 enzymes of the Candida species in the following order: 6a-j > 4a-j > fluconazole (the reference drug). The in vitro testing of the compounds against the Candida species showed lower MIC values for 6a-j than 4a-j, and for 4a-j than fluconazole, thus correlating well with the in silico findings. According to growth rescue assays, 6a-j and 4a-j (like fluconazole) inhibit ergosterol synthesis. The in silico toxicity assessment evidenced the safety of compounds 6a-j, which merit further research as possible antifungal drugs.
“…There are numerous oxazole-containing drugs have been reported and are widely used in market for the treatment of various kind of diseases, including such as ditazole (platelets aggregation inhibitor), oxaprozin, JTE-5229 COX-2 inhibitors (anti-inflammatory drug), (-)-muscoride A (peptide alkaloid), aleglitazar (antidiabetic), aristoxazole (anti-inflammatory drugs), and AD-5061 (antidiabetic agent) ( Fig. 2 ) ( Mukku et al, 2020 ). Fig.…”
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