(3a'R,4'S,5'S,6a'S)-5'-[[(1,1-Dimethylethyl)dimethylsilyl]oxy]hexahydro-N-[(1R)-2-hydroxy-1-phenylethyl]-5,5-dimethyl-spiro[1,3-dioxane-2,2'(1'H)-pentalene]-4'-carboxamide