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

2-(((bis(2-chloroethyl)carbamoyl)oxy)methyl)-4-((R)-2-((3S,8S,9S,10R,13R,14S,17R)-3-hydroxy-10,13-dimethyl-2,3,4,7,8,9,10,11,12,13,14,15,16,17-tetradecahydro-1H-cyclopenta[a]phenanthren-17-yl)propyl)pentane-1,5-diyl bis(bis(2-chloroethyl)carbamate)