Experimental Procedure

3-O-Acetyl-2-azido-4-(benzyloxycarbonyl)amino-2,4,6-dideoxy-D-galacto pyranosyl nitrate (13):

Acetate 12 (2.4 g, 7.9 mmol) dissolved in CH3CN (39.3 mL) at −25 °C was treated with cerium ammonium nitrate (12.9 g, 23.6 mmol) followed by NaN3 (767 mg, 11.8 mmol). Then, the mixture was stirred vigorously for 8 h between −20 °C and −25 °C. The reaction was diluted with cold Et2O (100 mL). The organic layer was then washed with cold H2O (3 x 100 mL), dried over Na2SO4, and concentrated under reduced pressure. The crude product was purified by flash chromatography (20:80 EtOAc/hexanes) to furnish nitrate 13 (2.14 g, 5.23 mmol) in 67% yield as a white foam. The nitrate mixture is made of three components: two galacto (2:1 α/β-anomeric mixture) and one talo (α-anomer) configured azides (3.5:1 dr galacto/talo). This mixture could not be separated by silica chromatography. Nitrate 13 has been previously synthesized, and our characterization data were consistent with the previously reported data. The material appears to be slightly unstable to silica gel: [α]D20 = +100.5° (c = 1.2, CHCl3); Rf = 0.62 (40:60 EtOAc/cyclohexane); 1H NMR (CDCl3, 400 MHz): δ 6.23 (d, J= 4.4 Hz, 1H; galacto α-nitrate), 6.15 (d, J= 0.8 Hz, 1H; talo α-nitrate), 5.50 (d, J= 8.8 Hz, 1H; galacto β-nitrate); 13C NMR (CDCl3, 100 MHz): δ 170.3, 170.2, 169.8, 157.2, 156.9, 156.8, 136.9, 136.4, 128.9, 128.9, 128.7, 128.7, 128.4, 128.4, 128.4, 128.1, 98.6, 98.5, 97.2, 73.8, 71.2, 70.6, 69.1, 68.4, 67.8, 67.6, 67.5, 67.2, 57.7, 57.3, 56.2, 52.5, 51.9, 51.3, 20.9, 20.9, 20.6, 16.8, 16.6, 16.5; IR (thin film) 3425, 3336, 3067, 3035, 2988, 2940, 2117, 1750, 1721, 1657, 1521, 1370, 1329, 1274, 1224, 1135, 1086, 1029, 824 cm-1; HRMS (ESI) calcd for C16H19N5O8 (M+H)+ 410.1312, found 410.1320 m/z.