(S)-2-[(8S,9S,10R,13S,14S,17R)-3-(tert-Butyl-dimethyl-silanyloxy)-10,13-dimethyl-2,3,4,7,8,9,10,11,12,13,14,15,16,17-tetradecahydro-1H-cyclopenta[a]phenanthren-17-yl]-propionaldehyde 、
1,3-丙二醇 在
4-甲基苯磺酸吡啶 作用下,
以90%的产率得到tert-Butyl-[(8S,9S,10R,13S,14S,17R)-17-((S)-1-[1,3]dioxan-2-yl-ethyl)-10,13-dimethyl-2,3,4,7,8,9,10,11,12,13,14,15,16,17-tetradecahydro-1H-cyclopenta[a]phenanthren-3-yloxy]-dimethyl-silane