(S)-2-Methyl-butyric acid (1S,4aR,7S,8S,8aS)-7-methyl-8-{2-[(2S,4S)-6-oxo-4-(tetrahydro-pyran-2-yloxy)-tetrahydro-pyran-2-yl]-ethyl}-1,2,3,4,4a,7,8,8a-octahydro-naphthalen-1-yl ester