Owing to having very strong bioactivity, oligo-peptides can be used as the medication or the pre-medication and become the studying focus now. Existing methods for synthesizing oligo-peptides included liquid phase peptide synthesis, solid phase peptide synthesis and enzymatic peptide synthesis. In this paper, a new method for synthesizing oligo-peptides by phosphorus oxychloride activation was reported. With the assistance of phosphorus oxychloride, the phosphorylation of L-valine could take place and then was assembled into oligo-peptides, which were analyzed by electrospray ionization mass spectrometry(ESI-MS). On quenching with methanol, the reaction mixtures, which were produced under different reaction conditions, yielded the corresponding peptide methyl esters. Moreover, we found that, as the reaction conditions such as reaction time, solvent and temperature were changed, the length of peptides changed. And the length of peptides could be controlled by changing the reaction conditions.
