(3aS,3a1R,4aS,4a1S,5aS,6R,8aS,8bS)-chloromethyl6-((ethoxycarbonyl)oxy)-3a1,5a-dimethyl-3-oxo-3,3a,3a1,4a,4a1,5,5a,6,7,8,8a,8b,9,10-tetradecahydro-2H-cyclopenta[1,2]phenanthro[4,5-bcd]furan-6-carboxylate