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Abstract
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An efficient synthesis of 5-arylidene-2,4-thiazolidinediones and 5-benzylidene rhodanines by the Knoevenagel condensation of 2,4-thiazolidinedione or rhodanine with aromatic aldehydes was studied. It proceeded smoothly in the presence of tetrabutylammonium hydroxide/H2O-EtOH to afford the corresponding products in high yields at 50◦C. Also, a series of dihydrothiophene derivatives were synthesized via the four-component reaction of aldehyde, malonitrile, 2,4-thiazolidinedione, and piperidine in the presence of Bu4NOH as a basic ionic liquid in aqueous medium. This new method offers several advantages, such as excellent yields, short reaction times, and simple procedure
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