Crystallisation of 2,3,4-tri-O-acetyl-α-d- and α-l-xylopyranosyl bromides in enantiomorphic space groups

Bromoacetates of α-d-xylose and α-l-xylose, compounds from the group of extensively explored carbohydrate substrates, were synthesised and structurally characterised. Crystallographic studies performed for both compounds respectively indicate that this pair of enantiomers crystallises in the pair of enantiomorphic space groups, P4₁2₁2 and P4₃2₁2, respectively. The chirality of these space groups is induced by the helical arrangement of the bromides in the crystals. Geometry of the synthesised bromoacetates is discussed based on crystallographic data and calculations performed using DFT methods. It was proved that the anomeric effect acts and that the acetyl groups are characteristically arranged in the bromoacetates.