乙酸酐   、                                                                                      
(22R)-23,23-difluoro-3α,22-dihydroxy-24,24-dimethyl-5α-cholan-6-one                                                                                                                                                              在
                                                                                                                                                                                 
吡啶                                                                                                                                  作用下,
                                                                                                                                                                                                                            生成                                                 Acetic acid (3R,5S,8S,9S,10R,13S,14S,17R)-17-((1S,2R)-2-acetoxy-3,3-difluoro-1,4-dimethyl-pentyl)-10,13-dimethyl-6-oxo-hexadecahydro-cyclopenta[a]phenanthren-3-yl ester