Crystal Structures of β-1-N-Chloroacetamido Derivatives of D-Glucose and D-Galactose

Crystal structures of 1-N-(β-D-glucopyranosyl)chloroacetamide (1), an inhibitor of glycogen phosphorylase, and the corresponding galactopyranosyl amide (2) have been determined. Both crystals belong to P212 121 space group with 1 having the unit cell dimensions of a = 7.939(3), b = 9.547(3) and c = 14.157(2) Å, while those of 2 are, a = 7.636(10), b = 9.004(8) and c = 14.807(5) Å. The sugar ring takes a 4C1 conformation and the amide linkage exists in Z-anti conformation in both crystals. The torsion angle O5-C1-N1-C1′ is -93.9(5) for 1 and -111.5(3)° for 2. The conformational preference of Cl and N1 in 1 and 2 is found to be between anti and gauche. The molecular assembly in both 1 and 2 is stabilized by a finite chain of hydrogen bonds starting from N1H and ending at O1′, whereas a ten membered hydrogen-bonded ring involving O4H and O5 is observed in 1.