丁二酸酐 、
methyl 3-[[(1S,4R,5R,9R,10R,12R,13R,14S,18R)-14-hydroxy-5,9-dimethyl-17-oxo-20-propan-2-ylpentacyclo[10.6.2.01,10.04,9.013,18]icos-19-ene-5-carbonyl]amino]propanoate 在
吡啶 、
4-二甲氨基吡啶 作用下,
反应 12.0h,
以77%的产率得到4-(((1S,4aR,4bS,6aR,7R,10aR,10bR,12R,12aR)-13-isopropyl-7-((3-methoxy-3-oxopropyl)carbamoyl)-7,10a-dimethyl-4-oxo-2,3,4,4a,5,6,6a,7,8,9,10,10a,10b,11,12,12a-hexadecahydro-1H-4b,12-ethenochrysen-1-yl)oxy)-4-oxobutanoic acid