(2R,5S,2'S,5'S,2''S,5''S)-1,2-O-Isopropylidene-5-<5'-<5''-<(tert-butyldiphenylsiloxy)methyl>tetrahydrofuran-2''-yl>tetrahydrofuran-2'-yl>pentane-1,2,5-triol