(2'S,3S,5R,6R,7R,8R,9S,10R,13S,14S,15S,16S)-Spiro[17H-dicyclopropa[6,7:15,16]cyclopenta[a]phenanthrene-17,2'(3'H)-furan]-4'-carboxylic acid, eicosahydro-3,5-dihydroxy-10,13-dimethyl-5'-oxo-, ethyl ester