Synthesis of novel cyclopeptide candidates: cyclo-[Nα -isophthaloyl - bis – (L-phenylalanyl - L-phenylalanine)-L-lysine] derivatives

A new series of cyclic pentapeptide candidates (7-9) was prepared via the coupling of Nα-isophthalic acid or dichloride with L-phenylalanine ester, yielding compound 3, Nα-isophthaloyl L-phenylalanine ester, which was hydrolyzed to the corresponding acid 4. Then, the Nα-isophthaloyl L-phenylalanine acid 4 was coupled with a second molecule of L-phenylalanine ester to afford tetrapeptide ester 5, which was hydrolyzed to acid 6. Moreover, cyclization of tetrapeptide acid 6, to give cyclic pentapeptide ester 7, acid 8, and hydrazide 9. The newly synthesized compounds (5-9) were characterized. KEY WORDS: Amino acids, Cyclopeptides, L-Phenylalanine, Nα-isophthaloyl-bis-peptides Bull. Chem. Soc. Ethiop. 2026, 40(2), 307-317 DOI: https://dx.doi.org/10.4314/bcse.v40i2.4