1,2,3,4-di-O-isopropylidene-α-D-galactooct-6-enopyrannuronate d'ethyle 、
靛红 、
DL-脯氨酸 以
甲苯 为溶剂,
反应 5.5h,
以84%的产率得到ethyl (1R,2S,3R)-2'-oxo-1-[(1S,2R,6R,8R,9S)-4,4,11,11-tetramethyl-3,5,7,10,12-pentaoxatricyclo[7.3.0.02,6]dodecan-8-yl]spiro[1,2,5,6,7,8-hexahydropyrrolizine-3,3'-1H-indole]-2-carboxylate