Toluene → 5,6-Dichloro-3-pyridinyl 2,3,4-tri-O-acetyl-5-thio-beta-D-xylopyranoside

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Reaction Conditions

Reaction Steps

5.1 g (37.5 mM) of zinc chloride are melted under reduced pressure, the melt is cooled under an inert atmosphere and then 12 ml of toluene, 12 ml of acetonitrile, 3 g of 4 Å molecular sieve and 2.45 g (15 mM) of 5,6-dichloro-3-pyridinol are added. The temperature of the mixture is brought to 90° C. and 3.78 g (37.5 mM) of triethylamine and 5.86 g (16.5 mM) of 2,3,4-tri-O-acetyl-5-thio-α-D-xylopyranosyl bromide are added. The reaction medium is stirred at 90° C. for 20 minutes and is then cooled and filtered to remove the inorganic salts, which are washed with ethyl acetate. The combined organic phases are washed with a 0.5 N sodium hydroxide solution and then the pH is brought to a value of 3 using a 0.1 N hydrochloric acid solution. The organic phase is subsequently washed with a saturated sodium chloride solution, dried over magnesium sulfate and concentrated under reduced pressure. The product is crystallized from ethyl ether and the desired product is obtained in the form of a light brown solid with a yield of 50%.

Provenance & Evidence