Glucosamine synton can be derived from branched oligosaccharides

In glycoconjugates, a lot of sugar chains, such as sialyl Le X and Le a, are branched at N-acetylglucosamine moieties in their structure. M1579, a GlcNAc derivative, is a useful sugar unit for synthesizing the branched oligosaccharides. Hydroxyl groups in M1579 at the C-3 position and the C-4 and C-6 positions are protected by an allyl group and a benzylidene group, respectively. These protective groups can be selectively cleaved, and then other sugar units, such as galactose, fucose, and sialic acid, or functional groups such as a sulfonyl group can be introduced at each hydroxyl group. On the other hand, because the phthaloyl group is used as a protective group for amines at the C-2 position, β-glycosides can be obtained after conversion of the 4-methoxyphenyl group at the anomeric position into various leaving groups.