6-Deoxy-6-fluoro-d-galactose

The crystal structure unequivocally confirms the relative stereochemistry of the title compound, C6H11FO5. The absolute stereochemistry was determined by the use of d-galactose as the starting material. The compound exists as a three-dimensional O—H⋯O hydrogen-bonded network with each molecule acting as a donor and acceptor for four hydrogen bonds.

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: LH5035). oxidation of alditols to give the corresponding ketoses, followed by enzymatic isomerisation to aldoses. Stereochemical diversity is introduced at C-2 in the keto-aldose isomerisation step and at C-3 by the epimerisation of ketoses, catalysed by D-tagatose-3-epimerase. In addition to the simple monosaccharides, this strategy is effective for the interconversion of deoxy (Gullapalli et al. 2010, Rao et al. 2009), methyl-branched (Jones et al. 2008) and azido (Jenkinson et al. 2009) sugars.
Fluorosugars have not been isolated from natural sources and consequently, in order to study metabolic processes, their passage along various biological pathways can be effectively tracked with the detection of fluorinated metabolites by 19 F NMR (Cobb et al. 2005). The fluoro modification of sugars affects their hydrogen bonding capability and fluorosugars have been shown to resemble deoxy sugars such as fucose and rhamnose in terms of enzymatic recognition (Caravano et al. 2009). Application of the Izumoring strategy to fluorinated substrates would allow the bulk preparation of fluorosugars, an important and interesting class of carbohydrates.
X-ray crystallography unequivocally confirmed the relative stereochemistry of the title compound. The absolute stereochemistry was determined by the use of D-galactose as the starting material. The compound exists as an extensively hydrogen-bonded lattice with each molecule acting as a donor and acceptor for 4 hydrogen bonds. Only classical hydrogen bonding is considered.

Refinement
In the absence of significant anomalous scattering, Friedel pairs were merged and the absolute configuration was assigned from the use of D-galactose as the starting material.
supplementary materials sup-2 The H atoms were all located in a difference map, but those attached to carbon atoms were repositioned geometrically. The H atoms were initially refined with soft restraints on the bond lengths and angles to regularize their geometry (C-H in the range 0.93-0.98, O-H = 0.82 Å) and U iso (H) (in the range 1.2-1.5 times U eq of the parent atom), after which the positions were refined with riding constraints. Fig. 1. Synthetic Scheme.