反应详情

Crude 3-O-benzyl-1,2:5,6-di-O-isopropylidene-α-D-glucofuranose (6) (23.5 g, 75.6 mmol) was dissolved in a 1:1:1 mixture of methanol, acetic acid and water (200 ml) and stood at 50° C. for 16 hours. The solvents were evaporated and the crude syrup purified by flash chromatography (ethyl acetate-hexane 3:2) to give 3-O-benzyl-1,2-O-isopropylidene-α-D-glucofuranose (18.1 g, 87%) as a clear oil, [α]20D -49.9° (c, 1.08 in chloroform) [lit.44 -50.8° (c, 1.24 in chloroform)]; 1H NMR δ 1.33, 1.49 (6H, 2×s, acetonide); 2.17 (2H, bs, 2×OH); 3.69, 3.81 (2H, 2×dd, H-6,6', J6,6' 11.4 Hz, J5,6 5.5 Hz, J5,6' 3.4 Hz); 4.00-4.15 (3H, m, H-3, H-4, H-5); 4.56, 4.73 (2H, 2×d, CH2Ph, JH,H' 11.7 Hz); 4.63 (1H, d, H-2); 5.94 (1H, d, 1-H,J1,2 3.7 Hz); 7.31-7.38 (5H, m, H-Ph).

1. customThe solvents were evaporated
2. customthe crude syrup purified by flash chromatography (ethyl acetate-hexane 3:2)