An efficient one-pot three-component reaction of 4-benzoyl-5-phenylamino-2,-3-dihydrothiophene-2,3-dione, diaminomaleonitrile, and alcohols with heteroatom substituents or several hydroxyl groups in acetonitrile solvent under reflux led to the formation of 5-(2-substituted ethoxy or propoxy-2-phenyl-1-Nphenylthiocarbamoylethenyl)-6-oxo-1,6-dihydropyrazine-2,3-dicarbonitrile derivatives in good yields.

Background: The present method is facile and effective for the synthesis of N-substituted 5-aryl-4-benzoyl-3-hydroxy-3-pyrrolin-2-one derivatives which are obtained by one-pot three-component condensation reactions of aromatic aldehydes, primary amines and ethyl benzoylpyruvate in the presence of a novel homogeneous catalyst including acidic pyridinium inner salt (PIS) at 50°C in ethanol and water mixture as solvent. Methods: 5-Aryl-4-benzoyl-3-hydroxy-3-pyrrolin-2-ones were synthesized through a one-pot three-component tandem formation of Schiff base cyclocondensation reaction of aromatic aldehydes, primary amines and ethyl benzoylpyruvate in the presence of 10 mol% of acidic pyridinium inner salt as a catalyst under aqueous ethanol medium at 50°C. All obtained structures were confirmed by their elemental analysis data and IR, 1H NMR and 13C NMR spectroscopy. Results: Three-component synthesis of 5-aryl-4-benzoyl-3-hydroxy-3-pyrrolin-2-ones catalyzed by acidic pyridinium inner salt with aromatic aldehydes, primary amines and ethyl benzoylpyruvate in aqueous ethanol medium at 50°C was prepared. The achieved derivatives (eight entries) were well synthesized in excellent yields. Conclusion: We found acidic pyridinium inner salt as a proper catalyst for this method. Catalyst Novelty is excellent catalytic activity, easy separation of the reaction mixture by washing with cold water and reusability of the catalyst for six consecutive periods without disrupting the activity of this catalyst system.