Copper-Catalyzed Synthesis of 2,4-Disubstituted Imidazolones

Significance

Reported is a simple and efficient ligand-free copper-catalyzed synthesis of 2,4-di­substituted imidazolones 3 by the reaction of 2-bromo-3-alkylacrylic acids 1 with amidines 2. After optimization, Cu₂O/Cs₂CO₃ was proven to be the most effective copper-base combination. The scope of the reaction was investigated with different 2-bromo-3-alkylacrylic acids and amidines. The only perceivable difference is in the nature of the amidine (aromatic amidine showed higher ­reaction activity than aliphatic). A plausible mechanism was proposed without evidence.