Electrochemical reduction of halogeno-sugars on silver : a new approach to C-disaccharide-like mimics

Electrochemical reduction on silver of tri-O-acetyl-α-D-fucopyranosyl bromide 3 affords (1 → 1′)-linked C-disaccharide-like mimics 6–8; reduction of 1,2:3,4-di-O-isopropylidene-6-deoxy-6-iodo-α-D-galactopyranose 5 provides 1,2:3,4-di-O-isopropylidene-6-deoxy-6-(1′,2′ : 3′,4′-di-O-isopropylidene-6′-deoxy-α-D-galactopyranos-6′-yl)-α-D-galactopyranose 9; simultaneous reduction of 5 and tetra-O-acetyl-α-D-glucopyranosyl bromide 1 or tri-O-acetyl-α-L-fucopyranosyl bromide 4 gives 9 and methylene-bridged C-disaccharide-like mimics 11, 12 or 13, 14, respectively.