乙酸酐 、
16α-benzoyloxy-3β,18,21-trihydroxypregn-5-en-20-one 18,20-hemiacetal 在
吡啶 作用下,
生成 Benzoic acid (3aR,4R,5aS,5bR,9S,11aR,11bS,13aR)-9-acetoxy-3-acetoxymethyl-3-hydroxy-11a-methyl-3a,4,5,5a,5b,6,8,9,10,11,11a,11b,12,13-tetradecahydro-3H-2-oxa-pentaleno[1,6a-a]phenanthren-4-yl ester