49] - 2-Acetamido-3,4,6-tri-O-acetyl-2-deoxy-α-d-glucopyranosyl Chloride

Abstract

This chapter focuses on the preparation of 2-acetamido-3,4,6-tri- O -acetyl-2-deoxy- α - d -glucopyranosyl chloride and 2-acetamido-2-deoxy- α - d -glucopyranose. It describes the procedure for the preparation of these two compounds. 2-amino-2-deoxy- α - d -glucose hydrochloride is converted into a supersaturated methanolic solution of the free base, and addition of excess acetic anhydride causes specific N-acetylation with the formation of crystalline 2-acetamido-2-deoxy- α - d -glucopyranose in almost quantitative yield. The acetamido sugar is treated with an excess of acetyl chloride and the spontaneous exothermic reaction that results gives 2-acetamido-3,4,6-tri- O -acetyl-2-deoxy- α - d -glucopyranosyl chloride directly, isolable crystalline in 75–85% yield. In the preparation of 2-acetamido-2-deoxy- α - d -glucopyranose, sodium (11.50 g, 500 mmoles) is added in small pieces to 500 ml of methanol in a 1-liter Erlenmeyer flask cooled in ice. The preparation of 2-acetamido-3,4,6-tri- O -acetyl-2-deoxy- α - d -glucopyranosyl chloride is carried out in a 500ml, round-bottomed flask equipped with a magnetic stirrer bar and a reflux condenser.