反应详情

To a solution of L-fucose (1.03 g, 6.09 mmol) in 60 mL of pyridine at room temperature is added acetic anhydride (4.6 mL, 4.96 g, 48.7 mmol). The solution is stirred at room temperature for 20 h and concentrated in vacuo. The residue is then dissolved in 50 mL of CH2Cl2 and washed with 5% HCl (4×60 mL), dried over anhydrous Na2SO4 and concentrated to afford 1.76 g (85%) of L-fucose tetraacetate 1 as a white foam, a 5:2 (α:β) mixture of anomers: Rf 0.38 (40% petroleum ether/EtOAc); 1H NMR (CDCl3, 270 MHz, mixture of anomers) δ 6.33 (d, J=2.0 Hz, 1H, H-1α), 5.67 (d, J=8.2 Hz, 1H, H-1β), 5.26-5.38 (m, 5H), 5.06 (dd, J=10.4, 3.4 Hz, 1H, H-3b), 4.27 (q, J=6.6 Hz, 1H, H-5α), 3.95 (q, J=6.3 Hz, 1H, H-5β), 2.23 (s, 3H), 2.19 (s, 3H), 2.18 (s, 3H), 2.17 (s, 3H), 2.15 (s, 3H), 2.04 (s, 3H), 2.02 (s, 3H), 2.01 (s, 3H), 1.22 (d, J=6.6 Hz, 3H, H-6β), 1.16 (d, J=6.6 Hz, 3H, H-6α).

1. concentrationconcentrated in vacuo
2. dissolutionThe residue is then dissolved in 50 mL of CH2Cl2
3. washwashed with 5% HCl (4×60 mL)
4. dry with materialdried over anhydrous Na2SO4
5. concentrationconcentrated