methyl (4R)-4-((3R,5R,8S,10S,13R,14S,17R)-3-acetoxy-12-(tert-butylperoxy)-10,13-dimethyl-2,3,4,5,6,7,8,10,12,13,14,15,16,17-tetradecahydro-1H-cyclopenta[a]phenanthren-17-yl)pentanoate