乙酸酐 、
methyl 3β-acetoxy-20α-hydroxy-16α,23(R)-epoxy-21-nor-17(ξ)-H-chola-5-enoate 在
三氟化硼乙醚 作用下,
反应 2.0h,
以90%的产率得到(2S,4aR,4bS,6aS,7R,9R,10aR,11aS,11bS)-2,7-Diacetoxy-4a,6a-dimethyl-1,2,3,4,4a,4b,5,6,6a,6b,7,8,9,10a,11,11a,11b,12-octadecahydro-10-oxa-indeno[2,1-a]phenanthrene-9-carboxylic acid methyl ester