Reaktion #2336040

Reaktionsgleichung

HBr

5-C-acetoxymethyl-1,2,3,4,6-penta-O-acetyl-L-arabino-hexopyranose

5-(acetoxymethyl)-1,2,3,4,6-penta-O-acetyl-L-arabino-hexopyranose

→

5-C-acetoxymethyl-2,3,4,6-tetra-O-acetyl-α-L-arabino-hexopyranosyl bromide

Lösungsmittel

acetic acid

Reaktionsbedingungen

Aufarbeitung

1. 1
   Waschendilution with methylene chloride (150 ml), washing with ice-water, sat. sodium bicarbonate solution, and water again
2. 2
   TrocknenAfter drying the methylene chloride solution
3. 3
   Sonstigewith sodium sulfate (anhydrous), evaporation of the solvent

Vorschrift

Glacial acetic acid (60 ml) is saturated with dry gaseous HBr for 30 minutes at 18°-20° C. This solution is mixed with 5-C-acetoxymethyl-1,2,3,4,6-penta-O-acetyl-L-arabino-hexopyranose (7) (6.0 g, 0.013 ml) and is stirred at an ambient temperature for 3.5 hours. Workup of the reaction mixture involves: dilution with methylene chloride (150 ml), washing with ice-water, sat. sodium bicarbonate solution, and water again. After drying the methylene chloride solution with sodium sulfate (anhydrous), evaporation of the solvent produces crude 5-C-acetoxymethyl-2,3,4,6-tetra-O-acetyl-α-L-arabino-hexopyranosyl bromide (18) (3 g) which is dried under high vacuum for 30 minutes and is used for the glycosidation reactions without further purification.

Quelle