Synthesis of halogenated-4-nitrophenyl 2-deoxy-2-halogeno-pyranosides via n-halogenosuccinimide activated glucal

Reaction of 3,4,6-tri-O-acetyl-D-glucal with silver 4-nitrophenolate in the presence of N-iodosuccinimide and N-bromosuccinimide produced (2,6-dihalo-4-nitro)phenyl 2-halo-2-deoxy--D-glycopyranosides. Although bromination and iodination of the 4-nitrophenyl group could not be avoided, the resulting (2,6-dihalo-4-nitro)phenylated compounds can be used as substrates or covalent glycosidase inhibitors after deprotection. The stereoselectivity and regioselectivity of the halogenation reactions are described.