New synthesis of 1,4-dideoxy-1,4-imino-d-galactitol from d-glucose propane-1,3-diyl dithioacetal

The treatment of 4-azido-4-deoxy-2,3:5,6-di-O-isopropylidene-d-galactose propane-1,3-diyl dithioacetal (derived from d-glucose) with mercuric chloride and mercuric oxide in aqueous acetone afforded 4-azido-4-deoxy-2,3:5,6-di-O-isopropylidene-d-galactose. Acid-catalyzed deprotection of the azido derivative, followed by catalytic hydrogenation and concomitant intramolecular reductive amination in the presence of 10% palladium on carbon, gave 1,4-dideoxy-1,4-imino-d-galactitol in good yield.