Indium-promoted Barbier-type allylations in aqueous media: a convenient approach to 4-C-branched monosaccharides and (1→4)-C-disaccharides Original Research Article

Starting from methyl 6-bromo-4,6-dideoxy-α-d-threo-4-enopyranoside, 4-C-branched sugars have been prepared through indium-promoted Barbier-type allylation of various aldehydes in aqueous media followed by hydroboration of the resulting double bond. The intermediate unsaturated monosaccharides were shown to rearrange in acidic media to give 4-C-acetyl-5-C-alkyl pyranose compounds. From β-1-formyl sugars the corresponding β-(1→4)-C-disaccharides were obtained.