PURPOSE: To effectively prepare the subject compound, by converting 1,2-O- isopropylidene-5-oxo-α-D-glucuronolactone hydrate into its oxime, catalytically hydrogenating the same, reducing the product by a hydride reducing agent, and reacting the reduced product with sulfur dioxide.

CONSTITUTION: A compound of formula I is reacted with O-(1-4C alkyl) hydroxylamine, O-benzyhydroxylamine or O-trimethylsilylhydroxylamine, to form its corresponding oxime of formula II. Then the oxime is catalytically hydrogenated in the presence of an amine protective reagent by using palladium on carbon, to form a protected amine lactone of formula III (APG is an amine protective group), and the same is reduced by a hydride reducing agent to form 5-amino-5-deoxy-1,2-O-isopropylidene-α-D-glucofuranose of formula IV. The compound is treated with a saturated aqueous sulfur dioxide to form 1- dioxynojirimycin-1-sulfonic acid, and then the compound is hydrogenated on Raney nickel to form 1-deoxynojirimycin.