Convenient synthesis of nucleosides of 2-deoxy-2-nitro-D-galactose and N-acetyl-D-galactosamine

A new method for the construction of nucleosides of 2-deoxy-2-nitro-D-galac tose and of N-acetyl-D-galactosamine based on addition reactions to 3,4,6-t ri-O-benzyl-2-nitro-D-galactal 4 (1) is presented. The reaction of imidazol e, benzimidazole, purine, N-6-benzyladenine, indazole, benzotriazole, and p yridone with 1 under base activation afforded the corresponding beta-glycos ides with a high degree of stereo- and regioselectivity. Reduction of the 2 -deoxy-2-nitro-nucleosides 3 and 4 gave, after N-acetylation, the correspon ding 2-acetamido-2-deoxy-nucleosides 9 and 10. Complete deprotection of 9 w as achieved with Hz in the presence of Pd(OH)(2)/C and THF as solvent.