81612-57-9 Picras-3-en-21-oic acid, 3,3'-((1,4-dioxo-1,4-butanediyl)bis(oxy))bis(13,20-epoxy-11,12-dihydroxy-15-(3-methyl-1-oxobutoxy)-2,16-dioxo-, dimethyl ester, (11beta,12alpha,15beta)-(11'beta,12'alpha,15'beta)-