Synthesizing method of sermaglutide

The invention discloses a synthesizing method of sermaglutide. The synthesizing method comprises the following steps of step 1, preparing Fmoc-Gly-Wang resin; step 2, using the Fmoc-Gly-Wang resin, protective amino acids, and octadecandioic acid (OtBu)-gamma-Glu-OtBu-PEG-PEG-OH as the raw materials to prepare full-protective peptide resin which contains Depsipeptide Units; step 3, performing TFA (trifluoroacetic acid) cracking on the peptide resin, so as to obtain crude peptide; step 4, dissolving the crude peptide obtained in step 3, adjusting the pH (potential of hydrogen) value, and converting ester bonds into amide bonds to react, so as to obtain a crude product of the sermaglutide. The synthesizing method has the advantages that by introducing the Depsipeptide Units, the problem of difficulty in sequential synthesizing of the sermaglutide is solved, and the target product is obtained by the reaction of converting the ester bonds into the amide bonds; the purity and yield of the crude peptide are improved