3,4,6-Tri-O-acetyl-1,2-O-[1-(exo-ethoxy)ethylidene]-β-D-mannopyranose 0.11-hydrate.

The title compound, C16H24O10·0.11H2O, is a key inter­mediate in the synthesis of 2-de­oxy-2-[18F]fluoro-d-glucose (18F-FDG), which is the most widely used mol­ecular-imaging probe for positron emission tomography (PET). The crystal structure has two independent mol­ecules (A and B) in the asymmetric unit, with closely comparable geometries. The pyran­ose ring adopts a 4C1 conformation [Cremer–Pople puckering parameters: Q = 0.553 (2) A, θ = 16.2 (2)° and φ = 290.4 (8)° for mol­ecule A, and Q = 0.529 (2) A, θ =15.3 (3)° and φ = 268.2 (9)° for mol­ecule B], and the dioxolane ring adopts an envelope conformation. The chiral centre in the dioxolane ring, introduced during the synthesis of the compound, has an R configuration, with the eth­oxy group exo to the manno­pyran­ose ring. The asymmetric unit also contains one water mol­ecule with a refined site-occupancy factor of 0.222 (8), which bridges between mol­ecules A and B via O—H⋯O hydrogen bonds.