5,8,13,17,22,25-Hexaoxanonacosanedioic acid,7,23-bis[[4-[2-(acetyloxy)-1-[(acetyloxy)methyl]ethoxy]-1,4-dioxobutoxy]methyl]-15-[4-[[(1,1-dimethylethyl)diphenylsilyl]oxy]-1,4-dioxobutoxy]-4,9,12,18,21,26-hexaoxo-, bis[2-(acetyloxy)-1-[(acetyloxy)methyl]eth