Acetic acid (3S,8S,9S,10R,13R,14S,17R)-17-[(R)-6-(tert-butyl-dimethyl-silanyloxy)-1,5-dimethyl-hexyl]-10,13-dimethyl-2,3,4,7,8,9,10,11,12,13,14,15,16,17-tetradecahydro-1H-cyclopenta[a]phenanthren-3-yl ester