Synthesis of β-D-threo-hexo-2,4-diulose, a radiolysis product of D-fructose

The regioselective activation of carbohydrate hydroxyl groups with bis(tributyltin) oxide and dibutyltin oxide is applied for the preparation of 4-O-acyl and 4-O-benzyl derivatives of 1,2-O-isopropylidene-β-D-fructopyranose. The 4-O-benzoyl derivative is converted into β-D-threo-hexo-2,4-diulose in four steps, including the ruthenium tetroxide oxidation of 3,5-di-O-(1-ethoxyethyl)-1,2-O-isopropylidene-β-D-fructopyranose