[1α,3β]-1,3-bis[(tetrahydro-2H-pyran-2-yl)oxy]pregn-5-en-21-oic acid ethyl ester 生成 ethyl (2R)-2-[(1S,3R,8S,9S,10R,13S,14S,17R)-10,13-dimethyl-1,3-bis(oxan-2-yloxy)-2,3,4,7,8,9,11,12,14,15,16,17-dodecahydro-1H-cyclopenta[a]phenanthren-17-yl]-5-[(4R)-2,2,4-trimethyl-1,3-dioxolan-4-yl]pentanoate