Co-crystals of 3-deoxy-3-fluoro-α-D-glucopyranose and 3-deoxy-3-fluoro-β-D-glucopyranose.
3-Deoxy-3-fluoro-D-glucopyranose crystallizes from acetone to give a unit cell containing two crystallographically independent molecules. One of these molecules (at site A) is structurally homogeneous and corresponds to 3-deoxy-3-fluoro-β-D-glucopyranose, C(6)H(11)FO(5), (I). The second molecule (at site B) is structurally heterogeneous and corresponds to a mixture of (I) and 3-deoxy-3-fluoro-α-D-glucopyranose, (II); treatment of the diffraction data using partial-occupancy oxygen at the anomeric center gave a high-quality packing model with an occupancy ratio of 0.84:0.16 for (II):(I) at site B. The mixture of α- and β-anomers at site B appears to be accommodated in the lattice because hydrogen-bonding partners are present to hydrogen bond to the anomeric OH group in either an axial or equatorial orientation. Cremer-Pople analysis of (I) and (II) shows the pyranosyl ring of (II) to be slightly more distorted than that of (I) [θ((I)) = 3.85 (15)° and θ((II)) = 6.35 (16)°], but the general direction of distortion is similar in both structures [ϕ((I)) = 67 (2)° (B(C1,C4)) and ϕ((II)) = 26.0 (15)° ((C3)TB(C1)); B = boat conformation and TB = twist-boat conformation]. The exocyclic hydroxymethyl (-CH(2)OH) conformation is gg (gauche-gauche) (H5 anti to O6) in both (I) and (II). Structural comparisons of (I) and (II) to related unsubstituted, deoxy and fluorine-substituted monosaccharides show that the gluco ring can assume a wide range of distorted chair structures in the crystalline state depending on ring substitution patterns.
University of Notre Dame, Department of Chemistry and Biochemistry, 251 Nieuwland Science Hall, Notre Dame, IN 46556-5670, USA.
Wenhui
W
Zhang
Allen G
AG
Oliver
Anthony S
AS
Serianni
D018360:Crystallography, X-Ray; D003847:Deoxyglucose / Q000031:analogs & derivatives* / Q000737:chemistry; D006860:Hydrogen Bonding; D008958:Models, Molecular; D008968:Molecular Conformation; D009005:Monosaccharides / Q000737:chemistry*
D009005:Monosaccharides; C007253:3-deoxy-3-fluoro-D-glucose; D003847:Deoxyglucose