4,24-Dioxa-3,25-disilaheptacosa-9,11,15,17,21-pentaen-7-one,19-[[(1,1-dimethylethyl)dimethylsilyl]oxy]-16-ethyl-2,2,3,3,6,8,10,14,20,25,25,26,26-tridecamethyl-5-[(1S)-1-methylpropyl]-,(5R,6S,8R,9E,11E,14R,15Z,17E,19R,20S,21Z)-