New system for peptide synthesis using N-acylpyrazoles

New system of peptide synthesis was described. The extension of one amino a cid unit on the peptide chain was constituted from only 2 reaction steps, t he conversion from esters to the corresponding N-acylpyrazoles and the subs equent aminolysis with amino eaters. This new system was distinctive from t he conventional peptide synthesis, which was consisted of 3 steps of the de protection, the activation and the condensation. Moreover, the key intermed iate N-acylpyrazoles exhibited the excellent properties of high sensitivity and separability for the chiral column on HPLC using the UV detector.