A solution of 10 grams of 1-deoxy-1-diazo-keto-L-fructose tetracetate and 0.01 gram of cupric acetate in 300 ml. of anhydrous acetic acid in a 2 liter flask was heated gently and after the initial violent evolution of gas had subsided, was brought just to the boiling point. The solvent was removed by distillation under reduced pressure, the final portion was removed by distillation with ethanol. The resulting syrup was dissolved in 15 ml. of ethanol, filtered and allowed to crystallize overnight in a refrigerator. This yielded 4 grams of crystals, m.p. 65° C. The syrup obtained from mother liquid was dissolved in 50 ml. of acetic anhydride containing 0.5 gram of zinc chloride (fresh fused), allowed to stand overnight at room temperature and heated 90 minutes at 50° C. Excess acetic anhydride was hydrolyzed by pouring into 200 ml. of ice-water and stirred for 2 hours. The acetylated sugar was extracted from the water with 200 ml. of chloroform. The chloroform solution was washed with water, dried over anhydrous sodium sulfate, filtered and evaporated to a syrup. This syrup was crystallized from 10 ml. of ethanol and yielded an additional 3 grams of product.
