Synthesis of N -glycosyl amides: conformational analysis and evaluation as inhibitors of β-galactosidase from E. coli .

The synthesis of N -glycosyl amides typically involves the use of glycosyl amines as direct precursors, resulting in low yields due to hydrolysis and the loss of stereocontrol through anomerization processes. In this study, a sequential synthesis of N -glycosyl amides is proposed, employing glycosyl amines as intermediates obtained from glycosyl azides. Derivatives with gluco , galacto , or xylo configurations were synthesized. Hexose derivatives were obtained under stereocontrol to give only the β anomer, while the xylo derivatives provided a mixture of α and β anomers. Conformational analysis revealed that all β anomers adopted the 4 C 1 conformation, while α anomers were found in the 1 C 4 chair as the major conformer. After de- O -acetylation, the derivatives containing a galactose unit were evaluated as inhibitors of β-galactosidase from E. coli and were found to be moderate inhibitors.