反应详情

2-(2-Methoxycarbonylethylthio)ethyl 2,3,4,6-tetra-O-acetyl-β-D-galactopyranoside (19) (1.00 g; 2.32 mmol) was dissolved in 25 ml of dry methanol and added to a solution of sodium methoxide in methanol, prepared from sodium (~0.05 g) and 10 ml of methanol. Stirring was continued for 4 h after which the reaction mixture was neutralized with Duolite-H+ (methanol washed and dried). Filtration and evaporation of the solvent gave a quantitative yield of the title compound (28; 590 mg) which was pure according to TLC (SiO2, chloroform/methanol/water 65:35:10) and NMR (D2O, TMS as an external standard): δ 4.44 (d, 1H, J1,2 =7.62 Hz, H1), 4.08 (m, 1H, OCH2 --CH2), 3.72 (s, 3H, OCH3), 3.52 (dd, 1H, H2), 2.92-2.70 (m, 6H, CH2S, CH2CO) 13C-NMR (D2O, TMS as an external standard) δ 178.2 (CO), 105.8 (C-1), 78.1, 75.6, 73.6, 71.5 (C2-C5), 71.7 (C-6), 63.8 (O--CH2 of aglycon) 55.2 (OCH3), 37.1, 33.7, 29.3 (--CH2 of aglycon).

1. filtrationFiltration and evaporation of the solvent