acetic acid 4-acetoxy-2-[2-(3,4-bis-benzyloxy-5-benzyloxymethyl-tetrahydro-furan-2-yloxy)-2-(3,4-bis-benzyloxy-5-ethoxy-tetrahydro-furan-2-yl)-ethoxy]-5-(1,2-diacetoxy-ethyl)-tetrahydro-furan-3-yl ester