Synthesis of ethyl 2-acetamido-6-S-(5-amino-5-deoxy-β-d-arabinopyranosyl)-2-deoxy-1,6-dithio-β-d-glucopyranoside: a sulfur-linked 5-amino-5-deoxyglycopyranosyl disaccharide

A novel pseudo-disaccharide having an imino sugar residue at the non-reducing end, namely, a sulfur-linked 5-amino-5-deoxyglycopyranosyl disaccharide, which is a potential specific inhibitor for glycosidases that recognize not only the glycosidic linkage but also the aglycone moiety, was synthesized. Glycosidation of N-Boc-5-amino-5-deoxy-d-arabinose with ethyl 2-acetamido-3,4-di-O-acetyl-2-deoxy-1,6-dithio-β-d-glucopyranoside in the presence of TsOH gave exclusively the corresponding 1,2-cis-linked thioglycoside. The interglycosidic linkage proved stable enough under conditions for the deprotection of the N-Boc group with TFA. This pseudodisaccharide was unstable at pH>5, but stable at lower pH. The sulfur-linked 5-amino-5-deoxyglycopyranosyl disaccharide was shown to be formed from 5-amino-5-deoxy-d-arabinose and ethyl 2-acetamido-2-deoxy-1,6-dithio-β-d-glucopyranoside in an acidic buffer solution.