Efficient Formation and Cleavage of Benzylidene Acetals by Sodium Hydrogen Sulfate Supported on Silica Gel

NaHSO 4 ·SiO 2 was used as an efficient heterogeneous catalyst for both the formation and the cleavage of benzylidene -acetals. This catalyst is compatible with many functional or protective groups. Under different solvent systems, either the formation or the cleavage of benzylidene acetals was carried out smoothly in -excellent yields and with good chemoselectivity.