Hydrochloric Acid → 3-Fluoro-4-formylbenzylidene-2,4-thiazolidinedione

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Reaction Steps

To a mixture of 4-dimethoxymethyl-3-fluorobenzaldehyde obtained in Example 37 (1.12 g, 5.66 mmol) and 2,4-thiazolidindione (795 mg, 6.79 mmol) in ethanol (20 mL) was added piperidine (0.68 mL, 6.8 mmol), and the mixture was heated to reflux for 13 h. Hydrochloric acid (1 mol/L) was added, and the mixture was extracted with ethyl acetate. The organic layer was combined, washed with brine, dried on anhydrous sodium sulfate, and concentrated under reduced pressure. To the residue were added tetrahydrofuran (25 mL) and hydrchloric acid (1 mol/L; 5 mL), and the mixture was stirred at room temperature for 20 h. Water was added, and the precipitated products were collected by filtration to afford 3-fluoro-4-formylbenzylidene-2,4-thiazolidinedione (696 mg, 49%).

Provenance & Evidence