21] Phosphorylated 3-deoxy-2-ketaldonic acids

Abstract

This chapter discusses the phosphorylated 3-deoxy-2-ketaldonic acids. The α -hydroxy group of a phosphorylated 3-deoxyaldonic acid is selectively oxidized by chlorate in the presence of vanadium oxide and phosphoric acid, and the keto acid is isolated by ion exchange chromatography. For the preparation of 3- deoxy-D-erythro-hex-2-ulosonic acid 6-phosphate, to a mixture of glucometasaccharinic acid 6-phosphate, 3 lithium salt (930 mg), commercial vanadium oxide (V 2 O 5 , 9 mg), and potassium chlorate (129 mg), 3 ml of water containing 0.105 ml of phosphoric acid (85%, d , 1.71) is added. The mixture is well shaken, and is passed through a column (100 ml) of Amberlite IR-120 (or Dowex 50) ion exchange resin in the H + form, and the pH of the acidic effluent is brought to 7.5 by addition of 1 N ammonium hydroxide solution. For the preparation of 3-deoxy-D-arabino-hept-2-ulosonic acid 7-phosphate, 2-Deoxy D-arabino- hexose 6-phosphate 6 (“2-deoxy D-glucose 6-phosphate”), 1.2 g, Li salt, are dissolved in water (5 ml) and KCN (780 mg) is added. The mixture is kept in a closed vessel in the cold room for 48 hr and then decationized by passing through a column (100 ml) of Amberlite IR-120 ion exchange resin in the H + form. For the preparation of 3-deoxy D-arabino- hept - 2-ulosonate 7-phosphate, the Ba salt (530 mg) is suspended in water (10 ml), and sufficient Amberlite IR-120 H + resin is added to bind all the Ba ions. The mixture is well stirred, and the resin is filtered off and thoroughly washed with water. 2-deoxyglucose 6-phosphate can be obtained from the relatively inexpensive 2-deoxyglucose by preparing its α -methyl pyranoside, which is transformed into the 6-phosphate.