A suspension of 5.6 g (15.8.10-3 mol) of 2,3,4-tri-O-acetyl-5-thio-α-D-xylopyranosyl bromide, 2 g (14.3.10-3 mol) of 4-nitrophenol, 4 g (29.3.10-3 mol) of zinc chloride and 3.8 g (21.7.10-3 mol) of silver imidazolate in 80 ml of anhydrous methylene chloride is stirred at 50° C., under an inert atmosphere, in the absence of light and in the presence of a molecular sieve (400 pm). After 48 h at this temperature, the reaction mixture is filtered on Celite®, washed with a 1N aqueous solution of hydrochloric acid, then a 1N solution of sodium hydroxide and finally water and dried over magnesium sulfate (MgSO4). After evaporation to dryness, the residue is purified by chromatography on silica gel using a hexane/ethyl acetate mixture (3/1 v/v) as the eluent. 1.5 g (yield: 25%) of the expected product are obtained by precipitation in ether.
