Amino acids and peptides—V: Novel peptide bond formation catalyzed by metal ions—III Elucidation of the formation mechanism

Abstract

Elucidation of the mechanism for peptide bond formation observed when an amino acid ester is treated with anhyd CuCl 2 in an anhyd alcoholic solvent, was attempted using results of IR and visible spectra measurements of the amino acid ester-CuCl 2 complex and accumulated experimental data. This novel reaction proceeds through a mechanism in which the amino anion produced by elimination of the proton from the Cu(II)-coordinating amino group, attacks the non-activated ester CO group of the amino acid ester which shares a common Cu(II) ion. It differs completely from the peptide formation reaction featuring a Co(III)-amino acid ester complex.