Imidazole‐catalyzed Three‐component Cascade Reaction for the Facile Synthesis of Highly Substituted 3,4‐Dihydropyridin‐2‐one Derivatives

A novel one‐pot protocol for the synthesis of valuable 3,4‐dihydropyridin‐2‐ones from the condensation of aldehyde with cyanoacetamide and 1,3‐dicarbonyl compounds in the presence of imidazole was developed. A series of aldehydes and 1,3‐dicarbonyl compounds were employed to examine the scope of substrates for this protocol. This reaction proceeded through the formation of one ring and four new bonds (two C? C, one C? N, one C?C) via the sequence involving Knoevenagel condensation, Michael addition and intramolecular cyclization with moderate to excellent yields. All new compounds were characterized by IR, ¹H NMR, ¹³C NMR and HRMS.