Acyl chloride/DABCO-promoted acetal migration of 1,2:4,5-di-O-isopropylidene-d-fructopyranose

An unprecedented acetal migration was observed when 1,2:4,5-di-O-isopropylidene-d-fructose was treated with various acyl chlorides and 1,4-diaza-bicyclo[2.2.2]octane (DABCO). 2,3:4,5-Di-O-isopropylidene-d-fructose derivatives were isolated as the only product in high to quantitative yields. The acylium cations generated in situ were speculated as the electrophilic species to initiate the migration process.