Acetic acid (E)-(4S,5S,10R,11S,12S,13R,15R)-15-benzyloxy-4-(tert-butyl-dimethyl-silanyloxy)-5,16-dimethoxy-10,12-dimethyl-9-oxo-13-triethylsilanyloxy-11-trimethylsilanyloxy-hexadec-7-enyl ester