(2’R,7R,8S,10R,13S,14S)-methyl 10,13-dimethyl-3,5′-dioxo-1,2,3,4′,5′,6,7,8,9,10,13,14,15,16-tetradecahydro-3’H-spiro[cyclopenta[a]phenanthrene-17,2′-furan]-7-carboxylate