Synthesis of 3-hexuloses from 1,2:5,6-di-O-isopropylidenehexitols

A simple, but low-yielding method for the synthesis of 3-hexuloses has been elaborated. Oxidation of 1,2:5,6-di-O-isopropylidenehexitols with bromine in the presence of barium carbonate, followed by mild-acid hydrolysis of the oxidation products gave the free hexuloses. Oxidation occurred at only one of the carbon atoms bearing free hydroxyl groups. From the d-mannitol derivative, d-arabino-3-hexulose was obtained via the di-O-isopropylidene derivative, whereas the d-glucitol derivative gave a mixture of the 1,2:5,6-di-O-isoprpylidene derivatives of l-xylo- and d-ribo-3-hexulose, separable by column chromatography. Mild-acid hydrolysis of the oxidation products afforded the free hexuloses.