(S)-2-{(S)-2-[(S)-2-((S)-2-Amino-propionylamino)-propionylamino]-3-methyl-pentanoylamino}-3-methyl-butyric acid benzyl ester 、
{(S)-2-[(S)-2-((S)-2-tert-Butoxycarbonylamino-3-methyl-butyrylamino)-3-methyl-butyrylamino]-4-methyl-pentanoylamino}-acetic acid 在
1-羟基苯并三唑 、
N,N'-二环己基碳二亚胺 作用下,
以
N,N-二甲基甲酰胺 为溶剂,
以76%的产率得到(S)-2-((S)-2-{(S)-2-[(S)-2-(2-{(S)-2-[(S)-2-((S)-2-tert-Butoxycarbonylamino-3-methyl-butyrylamino)-3-methyl-butyrylamino]-4-methyl-pentanoylamino}-acetylamino)-propionylamino]-propionylamino}-3-methyl-pentanoylamino)-3-methyl-butyric acid benzyl ester