Crystal structures of β-1-N-chloroacetamido derivatives of D-glucose and D-galactose

Crystal structures of 1-N-(beta-D-glucopyranosyl)chloroacetamide (1), an inhibitor of glycogen phosphorylase, and the corresponding galactopyranosyl amide (2) have been determined. Both crystals belong to P2(1)2(1)2(1) space group with 1 having the unit cell dimensions of a=7.939(3), b=9.547(3) and c=14.157(2) Angstrom, while those of 2 are, a=7.636(10), b=9.004(8) and c=14.807(5) Angstrom. The sugar ring takes a C-4(1) 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)degrees for 2. The conformational preference of C1 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.