(2S,3R)-3-(3-{(S)-1-[(S)-Azido-(tert-butoxycarbonylmethyl-carbamoyl)-methyl]-1-methyl-propoxy}-4-benzyloxy-phenyl)-2-(benzyloxycarbonyl-methyl-amino)-3-hydroxy-propionic acid 、 Val-SBn 在
(benzotriazo-1-yloxy)tris(dimethylamino)phosphonium hexafluorophosphate 、
N,N-二异丙基乙胺 作用下,
以62%的产率得到((2S,3S)-2-Azido-3-{2-benzyloxy-5-[(1R,2S)-2-(benzyloxycarbonyl-methyl-amino)-2-((S)-1-benzylsulfanylcarbonyl-2-methyl-propylcarbamoyl)-1-hydroxy-ethyl]-phenoxy}-3-methyl-pentanoylamino)-acetic acid tert-butyl ester