Réaction #6123

Équation de réaction

2,3,4-tri-O-acetyl-5-thio-α-D-xylopyranosyl bromide

2,3,4-tri-O-acetyl-5-thio-α-D-xylopyranosyl bromide

ethanol

2,3,4-tri-O-acetyl-5-thio-α-D-xylopyranosyl bromide

4-hydroxybenzonitrile

→

expected product

Rendement 112.5%

4-cyanophenyl 2,3,4-tri-O-acetyl-5-thio-β-D-xylopyranoside

Rendement 112.5%

Solvants

methylene chloride

Conditions de réaction

Traitement

1. 1
   workup.ADDITIONare then added
2. 2
   Filtrationthe reaction mixture is filtered on Celite®
3. 3
   Lavagewashed with a 1N aqueous solution of hydrochloric acid
4. 4
   Séchagewater and dried over magnesium sulfate
5. 5
   AutreAfter evaporation under reduced pressure
6. 6
   Autrethe residue is purified by chromatography on silica gel using a hexane/ethyl acetate mixture (3/1 v/v) as the eluent

Mode opératoire

A suspension of 6.5 g (12.3.10-3 mol) of 2,3,4-tri-O-acetyl-5-thio-α-D-xylopyranosyl bromide, 6 g (50.4.10-3 mol) of 4-hydroxybenzonitrile, 6.9 g (50.5.10-3 mol) of zinc chloride and 4.4 g (25.1.10-3 mol) of silver imidazolate in 200 ml of anhydrous methylene chloride is stirred at 40° C., under an inert atmosphere, in the absence of light and in the presence of a molecular sieve (400 pm). After 7 h at this temperature, 6.9 g (50.5.10-3 mol) of zinc chloride, 4.4 g (25.1.10-3 mol) of silver imidazolate and 6.5 g (18.3.10-3 mol) of 2,3,4-tri-O-acetyl-5-thio-α-D-xylopyranosyl bromide are added. The reaction medium is left overnight under these conditions and 6.5 g (12.3.10-3 mol) of 2,3,4-tri-O-acetyl-5-thio-α-D-xylopyranosyl bromide are then added. After 24 h, the reaction mixture is filtered on Celite® , washed with a 1N aqueous solution of hydrochloric acid and then water and dried over magnesium sulfate. After evaporation under reduced pressure, the residue is purified by chromatography on silica gel using a hexane/ethyl acetate mixture (3/1 v/v) as the eluent. 8.1 g (yield:41%) of the expected product are obtained by crystallization from ethanol.

Source