Abstract
Background: In the present study, we performed according to green chemistry’s standards, an easy and very efficient one-pot synthesis of2-thioxo-1,3-thiazolidin-4-one(rhodanine) and thiazolidine-2,4-dione (TZD) derivatives via Knoevenagel condensation of various aldehydes with rhodanine/ thiazolidine-2,4-dione in the presence of only 15 mole% of deep eutectic solvents (DESs) -choline chloride/urea- propionate and microwave radiation under solvent-free conditions.
Method: Twenty compounds were synthesized under thermal and microwave conditions and the yields of synthesized compounds were 77-90% and 81-95%, respectively. The IR spectra were obtained on a PerkineElmer FT-IR spectrophotometer using KBr disks.1H NMR and 13C NMR of products were registered Bruker 500 spectrometer and chemical shifts are expressed as d (ppm) with tetramethylsilane (TMS) as an internal standard in DMSO-d6 as a solvent. The purity of synthesized compounds was checked by chromatography and UV light (254 nm) was used for visualization.
Result: A range of rhodanine and -2, 4-thiazolidinedione derivatives were synthesized using ChCl/ urea catalyst under solvent -free conditions at 80°C. Then, the sample derivatives were synthesized under optimum conditions.
Conclusion: The mild reaction conditions, good to excellent yields, easy workup, without the involvement of any harmful solvents/chemicals and easily available substrates, they all facilitated in the preparation of all synthesized compounds.
Keywords: Deep Eutectic Solvents (DESs), green chemistry, knoevenagel condensation, microwave heating, solvent-free condition.
Graphical Abstract
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