(5R,6S)-5-Methyl-6-[(3Z,8Z,16Z)-(2S,5S,6R,7S,11S,12R,13R,14S,15S)-2,6,12-tris-(tert-butyl-dimethyl-silanyloxy)-14-(4-methoxy-benzyloxy)-5,7,11,13,15-pentamethyl-nonadeca-3,8,16,18-tetraenyl]-5,6-dihydro-pyran-2-one