Synthesis of the methyl α-glycosides of some isomalto-oligosaccharides specifically deoxygenated at position C-4

Methyl α-isomaltoside and methyl α-isomaltotrioside specifically deoxygenated at position C-4 of various glucopyranosyl units were synthesized by condensation of either 1,6-di-O-acetyl-2,3-di-O-benzyl-4-deoxy-α,β-d-xylo-hexopyranose (7) or 1,6-di-O-acetyl-2,3,4-tri-O-benzyl-α,β-d-glucopyranose (10) [mediated by silver perchlorate and tin(IV) chloride] with suitably blocked derivatives of methyl α-d-glucopyranoside, its 4-deoxy analog 6, or methyl 4′-deoxy α-isomaltoside (13), respectively.