Phosphorylated sugars. Part 25. Synthesis and behaviour in acidic media of 2-acetamido-2-deoxy-D-glucose 4- and 6-phosphates and of a ‘Lipid A’ analogue

Abstract

With the aid of 2-acetamido-2-deoxy-D-glucose 4- and 6-phosphates and of 2-amino-2-deoxy-D-glucose-6-phosphate, for all of which new and efficient syntheses are described, it has been shown that during treatment of 2-acetamido-2-deoxy-D-glucose 4-phosphate and of the model 2-hydroxyethyl 2-deoxy-2-[(3R)-3-hydroxytetradecanamido]-β-D-glucopyranoside 4-phosphate (which has also been synthesised) under conditions of acidic hydrolysis used in the determination of the structure of ‘Lipid A’ preparations from bacterial endotoxins, migration of the phosphate group from position 4 to position 6 takes place. Conditions are described in which the N-acetyl group is completely removed whilst the extent of phosphate migration is very small. Longer heating times in the same conditions are required to effect almost complete removal of the N-(3R)-3-hydroxytetradecanoyl group from the glucoside, but again very little phosphate migration occurs. The amount of inorganic phosphate formed after removal of the amide-bound substituent from the two 4-phosphates (7.5 and 15.4% respectively) was superior to that formed from N-acetylglucosamine 6-phosphate (2.4%).