Synthesis of 4H-imidazol-4-ones from α-Amino acids, and their Antioxidant Activities using Electron Transfer Methods

Abstract

A novel series of 4H-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 PCl3 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 PCl3 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 5i exhibited excellent antioxidant activity compared to the standard reference drugs, ascorbic acid and Trolox.