(R)-1-((S)-2-Amino-3-methyl-butyryl)-4-methylene-pyrrolidine-2-carboxylic acid ethyl ester 、
(2R,5S)-(6-ethoxy-5-isopropyl-2-methyl-3-oxo-2,3,4,5-tetrahydro-pyrazin-2-yl)-acetic acid pentafluorophenyl ester 在
三乙胺 作用下,
以
二氯甲烷 为溶剂,
以85%的产率得到1-{2(S)-[2-(6-ethoxy-5(S)-isopropyl-2(R)-methyl-3-oxo-2,3,4,5-tetrahydro-pyrazin-2-yl)-acetylamino]-3-methyl-butyryl}-4-methylene-pyrrolidine-2(R)-carboxylic acid ethyl ester