D-galactose, 2,3,4,5,6-pentaacetate → 1-deoxy-1-(4-hydroxyphenylthio)-2,3,4,6-tetra-O-acetyl-beta-D-galactopyranose

Beteiligte Stoffe

Reaktionsbedingungen

Reaktionsschritte

To a solution of galactose pentaacetate (3.30 g, 8.50 mmol) and 4-hydroxy-thiophenol (1.40 g, 11.1 mmol) in 50 mL of methylene chloride at -78° C. is added boron trifluoride diethyl ether complex (2.10 mL, 17.1 mmol ). The solution is allowed to warm slowly to 0° C. and then stirred for an additional hour at 0° C. The mixture is poured into saturated aqueous NaHCO3 (200 mL) and extracted with CH2Cl2 (2×150 mL), dried over Na2SO4, concentrated, and purified by flash chromatography (50% EtOAc/hexane) to give 3.90 g (99%) of 1-deoxy-1-(4-hydroxyphenylthio)-2,3,4,6-tetra-O-acetyl-β-D-galactopyranose 78 as a white solid: Rf 0.3 (50% EtOAc/hexane); 1H NMR (CDCl3, 300 MHz) δ 7.42 (d, J=8.6 Hz, 2H), 6.79 (d, J=8.6 Hz, 2H), 5.78 (br s, 1H), 5.39 (d, J=2.56 Hz, 1H, H-4), 5.15 (t, J=9.9 Hz, 1H, H-2), 5.00 (dd, J=3.3, 9.9 Hz, 1H, H-3), 4.56 (d, J=9.9 Hz, 1H, H-1), 4.19 (dd, J=6.6, 11.0 Hz, 1H), 4.09 (dd, J=6.6, 11.0 Hz, 1H), 3.89 (t, J=6.6 Hz, 1H, H-5), 2.12 (s, 3H, OAc), 2.09 (s, 3H, OAc), 2.05 (s, 3H, OAc), 1.97 (s, 3H, OAc).

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