Synthetic and structural studies of α-sialyl-(2 → 6) and α-sialyl-(2 → 3) 1-deoxynojirimycin derivatives potentially useful for biomedical applications

Suitably protected derivatives of 1-deoxynojirimycin (1,5-dideoxy-1,5-imino-d-glucitol, DNJ) and its d-galacto analog were coupled with 2-thioglycosides of N-acetylneuraminic acid. The resulting disaccharides were converted into a variety of α-sialyl-(2 → 6)- and α-sialyl-(2 → 3)-DNJ derivatives, including the cyclic lactams 6-O-(5-acetamido-3,5-dideoxy-d-glycero-α-d-galacto-2-nonulopyranosylono-1′,5-lactam)-1,5-dideoxy-1,5-imino-d-glucitol and -d-galactitol. The structural features of the synthetic compounds were investigated by ion-spray mass and 1H NMR spectrometry. The 1C4 conformation of N-tert-butoxycarbonyl-DNJ, a synthetic intermediate having the gluco configuration, was confirmed by X-ray crystallography.