Preparation of glycosyl bromides and chlorides

Preparation of 2,3,4,6-tetra-O-acetyl-a-D-glucopyranosyl bromide (acetobromo-glucose) [15]. 

Notes and discussion. This procedure is a basic method for the preparation of acetobromoglucose. In common with most methods is the use of HBr in glacial acetic acid some variants also include acetic anhydride as an added reagent, presumably to reverse any potential deacetylation. As a result of the anomeric effect the a-bromide is the major product. However, -bromide formation, which presumably occurs prior to anomerization to afford the a-anomer, and rapid hydrolysis during isolation are likely to account for the remaining mass balance [16]. 

Sodium hydrogencarbonate (aq., sat., 2 X 200 ml) Magnesium sulfate Ether for crystallization 

Round-bottomed flask (250 ml) with magnetic stirrer bar Magnetic stirrer Ice bath 

Preparation of 2-acetamido-3,4,6-tri-(9-acetyl-2-deoxy-a-D-glucopyranosyl chloride. 

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