The palladium(II)-promoted hydrolysis of methyl and isopropyl glycylglycinate

Abstract

The palladium(II)-promoted hydrolysis of methyl glycylglycinate and isopropyl glycylglycinate has been studied at four temperatures (25, 30, 35, and 40 °C) at I= 0.1 mol dm^–3 in the pH range 4–5. Under these conditions, and at a 1 : 1 metal to ligand ratio, the peptide esters act as tridentate ligands, donation occurring via the terminal amino-group, the deprotonated amide nitrogen, and the carbonyl group of the ester. Rate constants are reported for hydrolysis of the ester function by water and hydroxide ion, and activation parameters calculated. Base hydrolysis of the co-ordinated peptide esters is ca. 10⁵ times faster than the unprotonated peptide esters. Mechanisms for the reactions are considered.