Synthesis of (4<i>H</i>)‐Imidazol‐4‐ones from <i>α</i>‐Amino Acids, and their Antioxidant Activities using Electron Transfer Methods

Abstract A novel series of (4 H )‐imidazol‐4‐ones, designated as compounds 5(a–l) , were synthesized from phenylalanine and tyrosine. This synthesis involved derivatization of amino acids with phenylacetyl chloride, followed by cyclocondensation with aromatic amines using PCl 3 and a deep eutectic solvent as both catalyst and solvent. Amide intermediates were first produced via the Schotten‐Baumann reaction. These intermediates then underwent cyclization in the presence of PCl 3 and deep‐eutectic solvent, leading to the formation of imidazolones as potent antioxidants. The newly synthesized compounds were evaluated for their antioxidant activities using several electron transfer‐based assays, including DPPH, ABTS, FRAP, and CUPRAC. Among the tested compounds, compound 5 i exhibited excellent antioxidant activity compared to the standard reference drugs, ascorbic acid and Trolox.