Formaldehyde → 2-(p-Aminophenylthio)ethyl 4-O-(beta-D-galactopyranosyl)-beta-D-galactopyranoside

Participants

Reaction Steps

p-Aminothiophenol (205 mg; 1.64 mmol) was dissolved in dimethylformamide (4 ml). Sodium hydride (70 mg; 2.9 mmol) was added and the mixture was stirred under nitrogen for 20 min at room temperature. 2-Bromoethyl 2,3,6-tri-O-acetyl-4-O-(2,3,4,6-tetra-O-acetyl-β-D-galactopyranosyl)-β-D-galactopyranoside 14 (640 mg; 0.86 mmol) in dimethylformamide (7 ml) was added and the reaction mixture was stirred under nitrogen for 2 h (TLC:SiO2, ethyl acetate:isooctane 3:1) and poured into cold water (40 ml). The water solution was extracted with ether (4×20 ml) and the combined ether solutions were washed with water (10 ml) and dried (sodium sulfate). Evaporation gave a residue that contained a series of partly de-acetylated compounds. Evaporation of the water solution gave an additional amount of partly de-acetylated material. The combined residues were de-acetylated (sodium methoxide/methanol) and the product (after evaporation) was filtered through a column (SiO2, ethyl acetate/methanol 2:3) which gave crystalline (needles) 26. Yield: 425 mg (99%). Recrystallization from methanol gave an analytical sample: mp 104°-106°, [α]D 23 -0.8° (c 1.1; H2O); 1H-NMR (DMSO-D6 plus D2O, 50° C., TMS) δ 7.13, 6.58 (d, 2H each, J=8.5 Hz, aromatic H), 4.28 (d, 1H, J=7.0 Hz, H1'), 4.28 (d, 1H, J=7.5 Hz, H1), 2.90 (t, 2H, J=7.0 Hz, CH2 --S) ppm. 13C-NMR (DMSO-D6 plus D2O) δ 149.2, 136.6, 124.7, 119.7 (aromatic C), 107.0, 105.5 (Cl, Cl'), 79.7, 77.8, 76.9, 75.9, 75.5, 74.2, 73.9, 71.4, 70.7, (C2-C5, C2'-C5', CH2O), 63.8, 63.1 (C6, C6'), 37.6 (CH2 --S) ppm.

Provenance & Evidence