The 4-nitrobenzenesulfonyl group as a convenient N-protecting group for iminosugars—synthesis of oligosaccharide inhibitors of heparanase

The 4-nitrobenzenesulfonyl (nosyl) group can be used advantageously for the protection of the ring nitrogen atom of iminosugars. This group is conveniently introduced, is stable to most of the standard carbohydrate transformations and can be removed under mild conditions. The applicability of the nosyl group is demonstrated by the synthesis of sulfated oligosaccharides which are inhibitors of the enzyme, heparanase. The N-(4-nitrobenzenesulfonyl) group is orthogonal with the azido function.