Comparative X-ray single crystal study of acetylated-beta-D-galactopyranosyls azide and isothiocyanate

The structures of two peracetylated beta-D-galactopyranosides substituted a t the anomeric C atom with either an isothiocyanate or an azide group, have been determined by single crystal X-ray diffraction analysis: The two comp ounds show very similar molecular conformation, except for the substituent groups at the anomeric C atom and for the acetyl groups of the O6 atoms. Th ey crystallize in different infinite chain-type structures. While the isoth iocyanate group extends in a large intermolecular space, the azide group is placed in a more crowded environment.