Hydrazine hydrate (1:1) → 2-(2-Hydrazinocarbonylethylthio)ethyl beta-D-galactopyranoside

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2-(2-Methoxycarbonylethylthio)ethyl β-D-galactopyranoside (28) (500 mg) was dissolved in ethanol (99.5%; 2.5 ml) and hydrazine hydrate (85%; 1 ml) was added. The reaction mixture was left at room temperature over night (TLC; SiO2, chloroform/methanol/water 65:35:10, lower phase). Evaporation gave the title compound (29) as a syrup (pure by TLC and 1H-NMR) in quantitative yield. Recrystallization from ethanol gave the pure compound: mp 178°-179°; [α]D23 -2.2° (c 0.5; H2O); 1H-NMR (D2O, TMS as an external standard) δ 4.43 (d, 1H, J1,2 =7.7 Hz, H1), 4.07 (m, 1H, O--CH2 --CH2), 3.92-3.60 (m, 7H), 3.50 (dd, 1H, J2,3 =11.6 Hz, H2), 2.90, 2.86 (t, 2H each, J=7 Hz, --CH2S), 2.54 (t, 2H, CH2CO) 13C--NMR (D2O, TMS as an external standard) δ 176.1 (CO), 105.6 (C-1), 77.9, 75.4, 73.4, 71.6, 71.3 (C2-C6), 63.7 (O--CH2 --CH2), 36.5, 33.5, 29.9 (CH2S, CH2CO).

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