A simple approach to 3,6-branched galacto-oligosaccharides and its application to the syntheses of a tetrasaccharide and a hexasaccharide related to the arabinogalactans (AGs)

The preparation of 1,2:5,6-di-O-isopropylidene-α-d-galactofuranose was improved by increasing the ratio of DMF to acetone and using a solid supported catalyst. Employing the easily accessible 1,2:5,6-di-O-isopropylidene-α-d-galactofuranose as the starting glycosyl acceptor, a method which is particularly suitable for the regio- and stereoselective syntheses of 3,6-branched galacto-oligosaccharides was developed. A tetrasaccharide and a hexasaccharide related to the arabinogalactans (AGs) from plants were readily prepared using this strategy.