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