反应详情

2-Bromoethyl 2,3,6-tri-O-acetyl-4-O-(2,3,4,6-tetra-O-acetyl-α-D-galactopyranosyl)-β-D-galactopyranoside (15) (740 mg; 1 mmol) was dissolved in methanol (14 ml) by heating. Sodium methoxide in methanol (0.1M; 2 ml) was added and the reaction mixture was stirred at room temperature for 2 h. Sodium hydroxide (87 mg; 2.2 mmol) in water (2 ml) was added together with the catalyst (10% Pd/C; 120 mg) and the reaction mixture was hydrogenated (15 h) at atmospheric pressure. Filtration (Celite) and evaporation (<0.1 torr) gave a colorless, amorphous residue that was suspended in a mixture of acetic anhydride and pyridine (1:1; 10 ml). The reaction mixture was stirred (75°; 3 h), cooled and poured into ether (50 ml). The ether solution was washed (water, sat. sodium hydrogen carbonate solution, water), dried (sodium sulfate) and evaporated (<0.1 torr) which gave 33 as a crystalline residue that was pure by TLC (SiO2, ethyl acetate:isooctane 3:1). Yield: 650 mg (98%). Recrystallization from methanol-water gave an analytical sample (needles): mp 133°-135°; [α]D22 +81.4° (c 0.9; CHCl3); 1H-NMR (CDCl3, TMS) δ 5.57 (d, 1H, H4'), 5.39 (dd, 1H, J3',4' =3.2 Hz, H3'), 5.20 (dd, 1H, J2',3' =11.0 Hz, H2'), 5.18 (dd, 1H, J2,3 =10.8 Hz, H2), 5.01 (d, 1H, J1',2' =3.5 Hz, H1'). 4.82 (dd, 1H, J3,4 =2.6 Hz, H3), 4.48 (d, 1H, J1,2 =7.9 Hz, H1), 4.06 (d, 1H, H4), 3.92, 3.59 (dq, 1H each, J=9.7 and 7.1 Hz, CH3 --CH2 --O), 2.13, 2.11, 2.08, 2.075, 2.06, 2.04, 1.99 (s, 3H each, CH3 --CO), 1.22 (t, 3H, J=7.1 Hz, CH3 --CH2 -- O) ppm. 13C-NMR (CDCl3, TMS) δ 170.7, 170.6, 170.5, 170.4, 170.1, 169.7, 169.1 (CH3 --CO), 100.9 (Cl), 99.4 (Cl'), 77.2, 72.8, 71.9, 68.8, 68.6, 67.9, 67.4, 67.1 (C2-C5, C2'-C5'), 65.4 (CH2 --CH3), 62.1, 60.5 (C6, C6'), 21.0, 20.8, 20.7, 20.6 (CH3 --CO), 15.1 (CH2 --CH3) ppm.

1. temperatureby heating
2. custom(15 h)
3. filtrationFiltration (Celite) and evaporation (<0.1 torr)
4. customgave a colorless, amorphous residue that
5. stirringThe reaction mixture was stirred (75°; 3 h)
6. temperaturecooled
7. washThe ether solution was washed (water, sat. sodium hydrogen carbonate solution, water)
8. dry with materialdried (sodium sulfate)
9. customevaporated (<0.1 torr) which