Preparation method for liraglutide

The invention belongs to the technical field of preparation methods for polypeptide medicines, and particularly relates to a preparation method for liraglutide, aiming at solving the technical problems of difficult separation and purification, and low total yield and purity of products, of the existing preparation method. The technical scheme for solving the technical problems, disclosed by the invention is providing a preparation method for liraglutide. The method comprises the following steps of: preparing liraglutide resin via a solid-phase polypeptide method; performing acidolysis to obtain a liraglutide crude product; and finally purifying to obtain a liraglutide pure product, wherein the solid-phase polypeptide method comprises the step of sequentially connecting amino resin to corresponding protected amino acids or protected amino acid segments in the following sequences via a solid-phase coupling synthesis method, so as to prepare the liraglutide resin: Boc-W(Trt)-X(OtBu)-Thr(tBu)-Phe-Thr(tBu)-Ser(tBu)-Asp(OtBu)-Val-Ser(tBu)-Ser(tBu)-Tyr(tBu)-Leu-X(OtBu)-Gln(Trt) -Ala-Ala-Lys[Y(Alpha-OtBu)]-Glu(OtBu) -Phe-Ile-Ala-Trp(Boc)-Leu-Val-Z(Pbf)-Arg(Pbf)-Gly-resin, wherein W is His-Ala, X is Glu-Gly, Y is N alpha-PAL-Glu, and Z is Arg-Gly. The invention provides a novel method for shortening the production cycle, and improving the purity and the yield of the products.