tert-Butyl-[(2S,3R,4aS,8aS,9aR,10aR)-4a,5-dimethyl-2-((R)-2-methyl-3-phenylsulfanyl-propyl)-3,4,4a,7,8a,9,9a,10a-octahydro-2H-1,8,10-trioxa-anthracen-3-yloxy]-dimethyl-silane