反应详情

2-Bromoethyl 2,3,4,6-tetra-O-acetyl-β-D-galactopyranoside (1) (98 mg; 0.22 mmol) was dissolved in methanol (5 ml) and aqueous potassium hydroxide (0.3M, 5 ml) and hydrogenated (Pd/C 10%; 47 mg) at atmospheric pressure for 3 h. The reaction mixture (pH 6) was filtered and evaporated to give a residue that was pure by TLC (SiO2, chloroform/methanol/water 65:35:10, lower phase). The residue was acetylated (acetic anhydride/pyridine 1:1; 60°; 1.5 h) and the reaction mixture was cooled, filtered and evaporated with toluene and ethanol several times and finally dried (0.1 torr). Crystallization from ether/isooctane gave the title compound (32). Yield: 55 mg (68%). Mp 92°-93°; [α]D22 -31.0° (c 1.2; benzene); [α]D24 -14.4° (c 1.2; CDCl3) (Lit/56 mp 88°; [α]D20 -29.8° (c 10; benzene)]; 1 H-NMR (CDCl3, TMS) δ 5.40 (dd, 1H, J4,5 =1.0 Hz, J4,3 =3.5 Hz, H4), 5.22 (dd, 1H, J2,3 =10.5 Hz, J1,2 =8.0 Hz, H2), 5.02 (dd, 1H, H3), 4.48 (d, 1H, H1), 4.16 (m, 2H, H6), 3.93 (oct, 1H, Jgem =10.0 Hz, Jvic =7.0 Hz, OCH2CH3), 3.89 (dd, 1H, J5,6 ~4 Hz, H5) 3.60 (oct, 1H, OCH2CH3), 2.17, 2.07, 2.06, 1.99 (s, 3H each, CH3CO), 1.22 (t, 3H, OCH2CH3). 13C-NMR (CDCl3, TMS) δ 170.4, 170.3, 170.2, 169.4 (CO), 101.1 (Cl), 71.0, 70.6, 68.9, 67.1 (C2-C5), 65.7 (CH2CH3), 61.3 (C6), 20.8, 20.7, 20.7, 20.6 (CH3CO), 15.1 (CH2CH3).

1. filtrationThe reaction mixture (pH 6) was filtered
2. customevaporated
3. customto give a residue that
4. temperaturethe reaction mixture was cooled
5. filtrationfiltered
6. customevaporated with toluene and ethanol several times
7. customfinally dried (0.1 torr)
8. customCrystallization from ether/isooctane