Polystyrene-supported TiCl4 as a novel,efficient and reusable polymeric Lewis acid catalyst for the chemoselective synthesis and deprotection of 1,1-diacetates under eco-friendly conditions

Copolymer beads of styrene and divinylbenzene (5–7%) were synthesized and combined with titanium tetrachloride in CS₂ to form a stable complex. The PS/TiCl₄ complex was used as a mild and efficient polymer-supported Lewis acid catalyst for the preparation of 1,1-diacetates from various types of aldehydes under heterogeneous conditions at room temperature. Deprotection of the resulting 1,1-diacetates has also been achieved using the same catalyst in methanol. This new protocol has the advantages of easy availability, stability, reusability of the eco-friendly catalyst, high to excellent yields, chemoselectivity, simple experimental and work-up procedure. Moreover, this polymeric catalyst could be recovered easily and reused several times without significant loss in activity.