Butyric acid (R)-1-((1aR,3aR,3bS,5aS,6S,8aS,8bS,10aR)-3a,5a-dimethyl-10-oxo-hexadecahydro-cyclopenta[a]cyclopropa[2,3]cyclopenta[1,2-f]naphthalen-6-yl)-ethyl ester 在
4-甲基苯磺酸吡啶 、 lithium bromide 作用下,
以
N,N-二甲基乙酰胺 为溶剂,
反应 6.0h,
以46%的产率得到Butyric acid (R)-1-((5S,8S,9S,10R,13S,14S,17S)-10,13-dimethyl-6-oxo-4,5,6,7,8,9,10,11,12,13,14,15,16,17-tetradecahydro-1H-cyclopenta[a]phenanthren-17-yl)-ethyl ester