Acetyl-Tethering Silica as a Novel Reagent for Acetylation of Alcohols under Mild and Heterogeneous Conditions

During the multistep synthesis of natural products, the efficiency of the synthetic protocol employed often dependes largely on protection and deprotection of functional groups involved. To this end, protecting groups have been playing a curcial role during the synthesis of complex natural products.1 Among the various protecting groups used for hydroxyl function, acetyl is the most common group in view of its easy introduction,stability to acidic reaction conditions and also ease in its removal by mild alkaline hydrolysis. Acetylation is normally performed by using acetic anhydride or acetyl chloride in the presence of a base such as triethylamine or pyridine. Further, the rate of acetylation is known to be increased mainfoldly if 4-dimethylaminopyridine is used as a co-catalyst.2 p-Toluenesulfonic acid3 (a protic acid) and Lewis acids suc