1,2:4,5-Di-O-iso­propyl­idene-β-d-erythro-hexo-2,3-diulo-2,6-pyran­ose

The crystal structure of title compound, C₁₂H₁₈O₆, has been determined using single-crystal data. There are two independent mol­ecules in the asymmetric unit. NMR coupling constants, dihedral angles as well as puckering parameters indicate the ³S₀ conformation of the pyran­ose ring in both mol­ecules A and B. The cis-fused 1,3-dioxolane ring in both mol­ecules A and B, adopts an E₄ conformation. The second five-membered 1,3-dioxolane ring, in mol­ecule A, has an E₂ conformation, whereas in mol­ecule B, this 1,3-dioxolane ring adopts an E₄ conformation. Molecules A form a zigzag infinite chain along the b axis with mol­ecules B as side chains. This explains why the displacement ellipsoids of atoms of mol­ecule B are substantially larger than those of mol­ecule A.