Synthesis method of polypeptide impurity monosulfide

The invention discloses a synthesis method of a polypeptide impurity monosulfide, which comprises the following steps: step 1, synthesizing polypeptide resin according to a polypeptide sequence, and replacing one cysteine with Fmoc-Ser (HPO3Bzl)-OH or Fmoc-Ser (PO3Bz12)-OH; 2, after polypeptide resin coupling is finished, a mixed solution of organic alkali and DMF is adopted for reacting for 10 h or above; the mixed solution of organic alkali and DMF is composed of DMF containing 10% by volume of organic alkali; and 3, carrying out a reaction on the obtained resin at room temperature for 1-2 hours by using cracking reagents TFA, H2O and Tis in a volume ratio of 95: 2.5: 2.5, carrying out ice diethyl ether precipitation, washing with diethyl ether for multiple times, and carrying out vacuum drying to obtain the target product. The method is simple to operate, the target impurity is easy to obtain, and the purity and yield of the target impurity are improved. 本发明公开了一种多肽杂质单硫化物的合成方法，包括如下步骤：步骤一，根据多肽序列合成多肽树脂，其中一个半胱