Reaktionsschritte
A solution of N-acetylmannosamine (100 mg, 0.420 mmol) in pyridine (5 mL) was stirred at 0° C. To this solution was added acetic anhydride (5.0 mL, 53 mmol) and a catalytic amount of DMAP. The mixture was stirred overnight and allowed to warm to rt. Concentration and co-evaporation with toluene (6×10 mL) afforded the crude product which was purified via silica gel chromatography eluting with a gradient of 1:4 to 1:1 EtOAc/hexanes, yielding 153 mg (94%) of a viscous oil. IR (thin film): 3368, 2965, 2255, 1750, 1665, 1536 cm−1. 1H NMR (500 MHz, CDCl3): δ2.05 (app s, 6H), 2.051 (app s, 6H), 2.08 (app s, 9H), 2.08 (s, 3H), 2.085 (s, 3H), 2.09 (s, 3H), 3.79 (ddd, 1H, J=2.5, 5.3, 9.6), 4.02-4.05 (m, 2H), 4.08 (dd, 1H, J=2.4, 12.4), 4.27 (dd, 1H, J=3.8, 5.5), 4.29 (dd, 1H, J=3.2, 5.5), 4.62 (ddd, 1H, J=1.8, 4.5, 9.2), 4.76 (ddd, 1H, J=1.7, 4.0, 9.1), 5.04 (dd, 1H, J=4.0, 9.9), 5.11 (app t, 1H, J=9.7), 5.15 (app t, 1H, J=10.0), 5.32 (dd, 1H, J=4.5, 10.2), 5.84 (d, 1H, J=1.7), 5.92 (d, 1H, J=9.1), 6.00 (d, 1H, J=1.7), 6.01 (d, 1H, J=9.1). 13C NMR (125 MHz, CDCl3): δ20.5, 20.6, 20.7, 20.8, 23.1, 23.3, 49.3, 49.5, 50.7, 61.9, 62.1, 65.3, 65.5, 68.8, 70.1, 71.3, 73.4, 76.7, 77.0, 77.2, 90.6, 91.7, 169.6, 169.7, 169.9, 170.0, 170.2, 170.5. HRMS (FAB) m/z 412.1227 (MNa+C16H23NNaO10 requires 412.1220).
