3,8,16,18-Nonadecatetraen-2-one,6,12-bis[[(1,1-dimethylethyl)dimethylsilyl]oxy]-14-hydroxy-5,7,9,11,13,15-hexamethyl-, (3Z,5S,6S,7S,8Z,11S,12R,13R,14S,15S,16Z)-