(1R,7R,9R,12R,17R)-6,11-dimethylspiro[8,19-dioxahexacyclo[15.2.1.01,6.07,9.07,16.011,15]icosane-12,5'-oxolane]-2',3,18-trione 、
碘甲烷 在
四甲基胍 作用下,
生成 methyl (1R,9R,14R,17R)-2,15-dimethyl-5,5'-dioxospiro[18-oxapentacyclo[8.8.0.01,17.02,7.011,15]octadec-6-ene-14,2'-oxolane]-9-carboxylate