Synthesis, reactions, and crystal structure of 5-azido-6-O-benzoyl-3,5-dideoxy-3-fluoro-1,2-O-isopropylidene-α-D-gluc ofuranose

Abstract

5-Bromo-6-O-tert-butyldiphenylsilyl-5-deoxy-1,2-O-isopropylidene-β-L-t alofuranose (7) was obtained by treatment of 3,5-O-benzylidene-6-O-tert-butyldiphenylsilyl-1,2-O-isopropylidene-α-D -glucofuranose (3) with N-bromosuccinimide followed by Zemplen O-deacylation and an oxidation-reduction sequence. Nucleophilic displacement of the bromide in 7 with potassium azide readily gave the corresponding 5-azido-5-deoxy-allo derivative 8. Treatment of the 3-trifluoromethanesulphonate of 8 with tris(dimethylamino)sulphonium difluorotrimethylsilicate gave 5-azido-6-O-tert-butyldiphenylsilyl-3,5-dideoxy-3-fluoro-1,2-O-isopropy lidene-α-D-glucofuranose (17). The configuration at C-3 in 17 was confirmed by X-ray crystallography of the 6-benzoate 19.