(3S,3aR,5aS,7R,8aR,8bS)-2-[(2R,3S,7S)-3-(tert-butyldiphenylsiloxy)-7-hydroxy-2-methylnonanoyl]-3,3a,5a,6,7,8,8a,8b-octahydro-7-hydroxy-as-indacene-3-acetic acid κ-lactone pivalate