乙酸酐   、                                                                                      
3-((3S,5S,8R,9S,10S,13S,14S,17S)-3,17-Dihydroxy-10,13-dimethyl-hexadecahydro-cyclopenta[a]phenanthren-3-yl)-3-oxo-propionic acid methyl ester                                                                                                                                                                                                                                                                                                          生成                                                 3-((3S,5S,8R,9S,10S,13S,14S,17S)-17-Acetoxy-3-hydroxy-10,13-dimethyl-hexadecahydro-cyclopenta[a]phenanthren-3-yl)-3-oxo-propionic acid methyl ester