Sulfuric acid immobilized on silica: an efficient reusable catalyst for the synthesis of O-isopropylidene sugar derivatives

Sulfuric acid immobilized on silica proved to be an efficient catalyst for the synthesis of O-isopropylidene sugar derivatives from reducing sugars. The method is very simple and economic for large-scale synthesis in which the catalyst is recovered and reused several times. Reactions with d-glucose, d-galactose, d-mannose, l-rhamnose, l-arabinose, d-xylose and l-sorbose led to the formation of the corresponding thermodynamically stable di-O- and/or mono-O-isopropylidene derivatives in good to excellent yields.