methyl (3S,7S,8S,9S,10R,11R,13S,14S,17R)-5'-hydroxy-3,11-bis((methoxycarbonyl)oxy)-10,13-dimethyl-1,2,3,4,4',5',7,8,9,10,11,12,13,14,15,16-hexadecahydro-3'H-spiro[cyclopenta[a]phenanthrene-17,2'-furan]-7-carboxylate 在
2,2,6,6-tetramethyl-piperidine-N-oxyl 、
碳酸氢钠 、 sodium bromide 作用下,
以
二氯甲烷 、
水 为溶剂,
以100%的产率得到methyl (3S,7S,8S,9S,10R,11R,13S,14S,17R)-3,11-bis((methoxycarbonyl)oxy)-10,13-dimethyl-5'-oxo-1,2,3,4,4',5',7,8,9,10,11,12,13,14,15,16-hexadecahydro-3'H-spiro[cyclopenta[a]phenanthrene-17,2'-furan]-7-carboxylate