Phosphoryl group participation leads to peptide formation from N‐phosphorylamino acids

N-phosphorylated amino acids without a side chain functional group can transfer themselves into peptides after prolonged standing in solvents at warm temperatures. Seven N-phosphorylpeptides and free peptides were isolated and their structures determined. The phosphoryl group participation is the key to the peptide formation. An intramolecular mixed carboxylic-phosphoric anhydride intermediate was proposed for this type of reaction which might provide a clue to the function of the phosphoryl group in the phosphorylated enzymes and in the prebiotic synthesis of protein.