Synthesis method of cyclic pentapeptide

The invention discloses a synthesis method of cyclic pentapeptide. According to the synthesis method, the 'solid-liquid combined production' strategy is adopted, a proper condensation agent is used for a condensation reaction, linear pentapeptides are prepared respectively through a proper process, the cyclization site is located between N-methyl-leucine and leucine, and the efficiency of linear peptide preparation is effectively improved.The proper condensation agent is used for the condensation reaction, racemization in amido bond formation can be effectively reduced, therefore, the purity of a target product can be effectively improved, reaching 99% or above, the requirements of biological activity tests and clinical application can be fully met, and the synthesis method of cyclic pentapeptide has high medical value. The cyclization agent PyBOP is used for a cyclization reaction, the cyclization yield can be effectively increased and reach up to 84.2%.The synthesis method does not require complex purification by column chromatography, redundant amino acids can be simply washed away, the synthesis process is simple, the cost of raw materials is low, reaction conditions are mild, the purity is high, industrialization is easy, and the synthesis method has broad market prospects.