3,11,17-tris-(tert-butyl-dimethyl-silanyloxy)-16-(tert-butyl-dimethyl-silanyloxymethyl)-19-carbamoyloxy-7-hydroxy-2,4,10,12,14,18,20-heptamethyl-5-oxo-tetracosa-8,13,21,23-tetraenoic acid methyl ester