Novel cyclic tripeptides and substituted aromatic amino acids via ruthenium-activated S(N)Ar reactions

[formula: see text] Chlorophenylalanines eta 6-complexed to ruthenium undergo SNAr reactions with a variety of nucleophiles to form substituted phenylalanines exemplified by 4b. Extension of these reactions to intramolecular ruthenium-activated SNAr cyclizations led to three novel cyclic tripeptide systems (exemplified by 17 and 20).