[(4S)-2,2-dimethyl-1,3-dioxolan-4-yl]methyl (1S,4aS,4bR,8aR,10aS)-2,4b,8,8,10a-pentamethyl-4,4a,5,6,7,8a,9,10-octahydro-1H-phenanthrene-1-carboxylate                                                                                                                                                              在
                                                                                                                                                                                 
硫酸                                                                                                                                  作用下,
                                                                                                                以
                                                                                         
甲醇                                                                                  为溶剂,
                                                                                                                                                    反应 4.0h,
                                                                                                                以82%的产率得到(1S,4aS,4bR,8aR,10aS)-2,4b,8,8,10a-Pentamethyl-1,4,4a,4b,5,6,7,8,8a,9,10,10a-dodecahydro-phenanthrene-1-carboxylic acid (S)-2,3-dihydroxy-propyl ester