L-(-)-Sorbose → Diacetone L-sorbose

Participants

Reaction Steps

To 500 ml of acetone were added 20 g of L-sorbose and 250 mg of anhydrous cupric bromide, and the mixture was stirred for 7 hours under reflux in a warm-water bath at 57° to 58° C. The refluxing solvent was continuously dried with 30 g of molecular sieves 3A which was placed between the reaction vessel and the cooling tube. After cooling, a small amount of aqueous sodium hydrogencarbonate is added to the reaction mixture, and the acetone was distilled off under reduced pressure. The residue was dissolved in 300 ml of benzene, and the benzene solution was washed with aqueous sodium hydrogencarbonate and water, and dried over anhydrous magnesium sulfate. When the benzene was distilled off under reduced pressure, there was obtained 23.0 g (80%) of 2,3:4,6-di-O-isopropylidene-L-sorbofuranose (purity of not less than 98%) as a residue. The compound, when recrystallized from petroleum ether, showed a melting point of 77° to 78° C., and exhibited the same infrared absorption spectrum and nuclear magnetic resonance spectrum as those of the crystals as obtained in Example 5.

Provenance & Evidence