1,2:3,4-di-O-Isopropylidene-beta-L-arabinopyranose

1,2:3,4-di-o-isopropylidene-beta-l-arabinopyranose ; 1,2:3,4-di-o-isopropylidene-alpha-l-arabinopyranose ; 1-o,2-o:3-o,4-o-diisopropylidene-?-l-arabinopyranose ; 1,2:3,4-bis-o-(1-methylethylidene)-b-l-arabinopyranose ; 1,2:3,4-bis-o-(1-methylethylidene)-beta-l-arabinopyranose ; 1-o,2-o:3-o,4-o-bis(1-methylethylidene)-?-l-arabinopyranose