(S)-6-Amino-2-[2-(5-methyl-2,4-dioxo-3,4-dihydro-2H-pyrimidin-1-yl)-acetylamino]-hexanoic acid benzyl ester 、 (S)-6-tert-Butoxycarbonylamino-2-[2-(5-methyl-2,4-dioxo-3,4-dihydro-2H-pyrimidin-1-yl)-acetylamino]-hexanoic acid 在
1-羟基苯并三唑 、
N,N-二异丙基乙胺 、
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,
生成
(S)-6-{(S)-6-tert-Butoxycarbonylamino-2-[2-(5-methyl-2,4-dioxo-3,4-dihydro-2H-pyrimidin-1-yl)-acetylamino]-hexanoylamino}-2-[2-(5-methyl-2,4-dioxo-3,4-dihydro-2H-pyrimidin-1-yl)-acetylamino]-hexanoic acid benzyl ester