Trimetaphosphate‐Induced Addition of Aspartic Acid to Oligo(glutamic acid)s

When a solution containing 0.01M decaglutamic acid, 0.1–1.0M aspartic acid, 1.0M MgCl₂, and 0.5M sodium trimetaphosphate is allowed to stand at temperatures in the range 0–50°, addition products containing up to ten aspartic acid residues are formed. Addition occurs to the side‐chain carboxy moieties, not to the terminal amine of the decaglutamic acid. A number of other amino acids including glutamic acid, glycine, and histidine fail to react with decaglutamic acid under the same conditions. We believe that the activation of aspartic acid leads to the formation of a cyclic anhydride that is the key intermediate in the reaction.