28-acetoxybetulin 、
异氰酸乙酯 以
氯仿 为溶剂,
反应 48.0h,
以90%的产率得到[(1R,3aS,5aR,5bR,7aR,9S,11aR,11bR,13aR,13bR)-9-(ethylcarbamoyloxy)-5a,5b,8,8,11a-pentamethyl-1-prop-1-en-2-yl-1,2,3,4,5,6,7,7a,9,10,11,11b,12,13,13a,13b-hexadecahydrocyclopenta[a]chrysen-3a-yl]methyl acetate