23R,25R-23-bromo-5α-spirostan-3β-ol-12-one acetate 在
氢氧化钾 作用下,
以
乙二醇 为溶剂,
以60%的产率得到(1'R,2'S,3R,4'S,6R,7'S,8'R,9'S,12'S,13'S,16'S,18'S)-16'-hydroxy-3,7',9',13'-tetramethylspiro[2,3-dihydropyran-6,6'-5-oxapentacyclo[10.8.0.02,9.04,8.013,18]icosane]-10'-one