(R)-2-[((1R,3aS,5aR,5bR,7aR,9S,11aR,11bR,13aR,13bR)-9-Hydroxy-1-isopropenyl-5a,5b,8,8,11a-pentamethyl-icosahydro-cyclopenta[a]chrysene-3a-carbonyl)-amino]-4-methyl-pentanoic acid 、
2,2-二甲基琥珀酸酐 在
吡啶 、
4-二甲氨基吡啶 作用下,
生成 4-[[(1R,3aS,5aR,5bR,7aR,9S,11aR,11bR,13aR,13bR)-3a-[[(1R)-1-carboxy-3-methyl-butyl]carbamoyl]-1-isopropenyl-5a,5b,8,8,11a-pentamethyl-1,2,3,4,5,6,7,7a,9,10,11,11b,12,13,13a,13b-hexadecahydrocyclopenta[a]chrysen-9-yl]oxy]-2,2-dimethyl-4-oxo-butanoic acid 、 4-[[(1R,3aS,5aR,5bR,7aR,9S,11aR,11bR,13aR,13bR)-3a-[[(1R)-1-carboxy-3-methyl-butyl]carbamoyl]-1-isopropenyl-5a,5b,8,8,11a-pentamethyl-1,2,3,4,5,6,7,7a,9,10,11,11b,12,13,13a,13b-hexadecahydrocyclopenta[a]chrysen-9-yl]oxy]-3,3-dimethyl-4-oxo-butanoic acid