(2’R,8R,9S,10R,13S,14S)-4′-butyl-3′,10,13-trimethyl-1,6,7,8,9,10,11,12,13,14,15,16-dodecahydro-5’H-spiro[cyclopenta[a]phenanthrene-17,2′-furan]-3,5′(2H)-dione