methyl 1α,3β-bis(tert-butyldimethylsilyloxy)-17β-hydroxy-20-methoxy-5,7,pregnadien-21-oate 生成 methyl (2Z)-2-[(1S,3R,9S,10R,13S,14S)-1,3-bis[[tert-butyl(dimethyl)silyl]oxy]-10,13-dimethyl-1,2,3,4,9,11,12,14,15,16-decahydrocyclopenta[a]phenanthren-17-ylidene]-2-methoxyacetate